Dr. Yang Sun MD.PhD. is a Professor of Ophthalmology at Stanford University School of Medicine. Dr. Sun is a clinician-scientist with clinical specialty in glaucoma medical and surgical management, as well as cataract surgery. He practices at both Byers Eye Institute at Stanford as well as Palo Alto VA medical center. He is the Laurie Kraus Lacob Faculty Scholar at Stanford Child Health Research Institute. Dr. Sun received his BA in Biophysics from Johns Hopkins University, followed by a MD.PhD. degree from Washington University School of Medicine. He completed Ophthalmology residency at Stanford University and a prestigious Heed fellowship at University of Michigan, Ann Arbor. He has been continuously funded by National Eye Institute and Veterans Administration. Dr. Sun’s research in glaucoma has also been funded by American Glaucoma Society, Lowe Syndrome Association, Knights Templar Eye Foundation, and Matilda Ziegler Foundation. Dr. Sun holds several U.S. patents on novel regulators of eye pressure and is the primary investigator on a number of glaucoma clinical trials. He is a member of Stanford BioX faculty and he was recently elected as a member of American Society of Clinical Investigators.
Dr. Sun studies pediatric diseases of congenital glaucoma and retinal degeneration, in particular with Lowe syndrome and Joubert syndrome. In the laboratory, Dr. Sun's team uses advanced technologies of patient-based iPS cells, CRISPR gene editing, optogenetics, and functional retinal imaging to discover mechanism of disease and develop new treatments for these blinding diseases.

Clinical Focus

  • Glaucoma Specialist

Academic Appointments

Administrative Appointments

  • Vice Chair, Academic Affairs, Ophthalmology (2022 - Present)

Honors & Awards

  • Laurie Kraus Lacob Faculty Scholar in Pediatric Translational Medicine, Child Health Research Institute (9/2018-8/2023)
  • Translational Vision Summit finalist, ARVO (2017)
  • American Glaucoma Society MAPS award, AGS (2012)
  • Starr Shulman Travel fellowship, California Ophthalmology Society (2009)
  • Heed Fellow, Heed Ophthalmic Foundation (2009)
  • William Ellis Research Prize, Washington University in St. Louis (2005)
  • Spencer T Olin Fellowship, Washington University in St. Louis (2003)
  • Barry Goldwater Scholarship, U.S. Congressional Goldwater Scholarship foundation (1998)

Boards, Advisory Committees, Professional Organizations

  • Member, International Society for Eye Research (2016 - Present)
  • Member, Association for Research in Vision and Ophthalmology (2008 - Present)
  • Member, American Academy of Ophthalmology (2009 - Present)
  • Member, American Glaucoma Society (2009 - Present)

Professional Education

  • Residency: Stanford University Ophthalmology Residency (2009) CA
  • Fellowship: University of Michigan Dept of Ophthalmology (2010) MI
  • Internship: St Louis University School of Medicine (2006) MO
  • Medical Education: Washington University in St Louis Registrar (2004) MO
  • Board Certification: American Board of Ophthalmology, Ophthalmology (2011)
  • Board Certification, Ophthalmology, American Board of Ophthalmology (2011)
  • Fellowship, University of Michigan, Ann Arbor, Glaucoma (2010)
  • Internship, St. Louis University (2006)
  • Residency, Stanford University (2009)
  • PhD, Washington University in St. Louis, Molecular Cell Biology (2004)
  • MD, Washington University in St. Louis, Medicine (2004)


  • Yang Sun. "United States Patent 941,601 Targeting Primary Cilia in Glaucoma Treatment", Aug 30, 2016

Current Research and Scholarly Interests

We are interested in the role of inositol phosphatases in eye development and disease, using both animal models and human disease tissue. We are a translational laboratory seeking to understand the basic function of proteins as well as developing therapeutic strategies for clinical trials.

2023-24 Courses

Stanford Advisees

All Publications

  • Primary cilia formation requires the Leigh syndrome-associated mitochondrial protein NDUFAF2. The Journal of clinical investigation Lo, C. H., Liu, Z., Chen, S., Lin, F., Berneshawi, A. R., Yu, C. Q., Koo, E. B., Kowal, T. J., Ning, K., Hu, Y., Wang, W. J., Liao, Y. J., Sun, Y. 2024; 134 (13)


    Mitochondria-related neurodegenerative diseases have been implicated in the disruption of primary cilia function. Mutation in an intrinsic mitochondrial complex I component NDUFAF2 has been identified in Leigh syndrome, a severe inherited mitochondriopathy. Mutations in ARMC9, which encodes a basal body protein, cause Joubert syndrome, a ciliopathy with defects in the brain, kidney, and eye. Here, we report a mechanistic link between mitochondria metabolism and primary cilia signaling. We discovered that loss of NDUFAF2 caused both mitochondrial and ciliary defects in vitro and in vivo and identified NDUFAF2 as a binding partner for ARMC9. We also found that NDUFAF2 was both necessary and sufficient for cilia formation and that exogenous expression of NDUFAF2 rescued the ciliary and mitochondrial defects observed in cells from patients with known ARMC9 deficiency. NAD+ supplementation restored mitochondrial and ciliary dysfunction in ARMC9-deficient cells and zebrafish and ameliorated the ocular motility and motor deficits of a patient with ARMC9 deficiency. The present results provide a compelling mechanistic link, supported by evidence from human studies, between primary cilia and mitochondrial signaling. Importantly, our findings have significant implications for the development of therapeutic approaches targeting ciliopathies.

    View details for DOI 10.1172/JCI175560

    View details for PubMedID 38949024

  • Adaptive selection at G6PD and disparities in diabetes complications. Nature medicine Breeyear, J. H., Hellwege, J. N., Schroeder, P. H., House, J. S., Poisner, H. M., Mitchell, S. L., Charest, B., Khakharia, A., Basnet, T. B., Halladay, C. W., Reaven, P. D., Meigs, J. B., Rhee, M. K., Sun, Y., Lynch, M. G., Bick, A. G., Wilson, O. D., Hung, A. M., Nealon, C. L., Iyengar, S. K., Rotroff, D. M., Buse, J. B., Leong, A., Mercader, J. M., Sobrin, L., Brantley, M. A., Peachey, N. S., Motsinger-Reif, A. A., Wilson, P. W., Sun, Y. V., VA Million Veteran Program, Giri, A., Phillips, L. S., Edwards, T. L. 2024


    Diabetes complications occur at higher rates in individuals of African ancestry. Glucose-6-phosphate dehydrogenase deficiency (G6PDdef), common in some African populations, confers malaria resistance, and reduces hemoglobin A1c (HbA1c) levels by shortening erythrocyte lifespan. In a combined-ancestry genome-wide association study of diabetic retinopathy, we identified nine loci including a G6PDdef causal variant, rs1050828 -T (Val98Met), which was also associated with increased risk of other diabetes complications. The effect of rs1050828 -T on retinopathy was fully mediated by glucose levels. In the years preceding diabetes diagnosis and insulin prescription, glucose levels were significantly higher and HbA1c significantly lower in those with versus without G6PDdef. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial, participants with G6PDdef had significantly higher hazards of incident retinopathy and neuropathy. At the same HbA1c levels, G6PDdef participants in both ACCORD and the Million Veteran Program had significantly increased risk of retinopathy. We estimate that 12% and 9% of diabetic retinopathy and neuropathy cases, respectively, in participants of African ancestry are due to this exposure. Across continentally defined ancestral populations, the differences in frequency of rs1050828 -T and other G6PDdef alleles contribute to disparities in diabetes complications. Diabetes management guided by glucose or potentially genotype-adjusted HbA1c levels could lead to more timely diagnoses and appropriate intensification of therapy, decreasing the risk of diabetes complications in patients with G6PDdef alleles.

    View details for DOI 10.1038/s41591-024-03089-1

    View details for PubMedID 38918629

  • Comparing a Head-Mounted Smartphone Visual Field Analyzer to Standard Automated Perimetry in Glaucoma: A Prospective Study. Journal of glaucoma Wang, S. K., Tran, E. M., Yan, W., Kosaraju, R., Sun, Y., Chang, R. T. 2024


    Wang et al compare an FDA-registered head-mounted smartphone device (PalmScan VF2000) with standard automated perimetry (SAP) in glaucoma patients and find that the head-mounted device may not fully recapitulate SAP testing.This study prospectively compared visual field testing using the PalmScan VF2000 Visual Field Analyzer, a head-mounted smartphone device, with standard automated perimetry (SAP).Patients with glaucoma undergoing Humphrey Field Analyzer SAP testing were asked to complete in-office PalmScan testing using a Samsung S5 smartphone in a virtual reality-style headset. Glaucoma severity was defined as SAP mean deviation (MD) >-6 dB for mild, between -6 and -12 dB for moderate, and <-12 dB for severe. Global parameters MD and pattern standard deviation (PSD) from PalmScan and SAP were compared using t-tests and Bland-Altman analyses. Bland-Altmann analyses of PalmScan and SAP MD were conducted for the superonasal, superotemporal, inferonasal, and inferotemporal visual field quadrants. The repeatability of PalmScan was assessed using Spearman's correlations and intraclass correlation coefficients (ICCs).Fifty-one patients (51 eyes) completed both SAP and PalmScan testing and met criteria for analysis. Compared to SAP, global MD and PSD measurements from PalmScan differed by an average of +0.62±0.26 dB (range: -3.25 to +4.60 dB) and -1.00±0.24 dB (range: -6.03 to +2.77 dB), respectively, while MD scores from individual visual field quadrants differed by as much as -6.58 to +11.43 dB. Agreement of PalmScan and SAP in classifying glaucoma severity was 86.3% across all eyes. PalmScan and SAP identified the same quadrant as having the worst visual field defect in 66.7% of eyes.Despite advantages in cost and accessibility, the PalmScan head-mounted perimetry device may not be able to fully recapitulate SAP testing.

    View details for DOI 10.1097/IJG.0000000000002452

    View details for PubMedID 38884623

  • Optineurin-facilitated axonal mitochondria delivery promotes neuroprotection and axon regeneration. bioRxiv : the preprint server for biology Liu, D., Webber, H. C., Bian, F., Xu, Y., Prakash, M., Feng, X., Yang, M., Yang, H., You, I., Li, L., Liu, L., Liu, P., Huang, H., Chang, C., Liu, L., Shah, S. H., Torre, A. L., Welsbie, D. S., Sun, Y., Duan, X., Goldberg, J. L., Braun, M., Lansky, Z., Hu, Y. 2024


    Optineurin (OPTN) mutations are linked to amyotrophic lateral sclerosis (ALS) and normal tension glaucoma (NTG), but a relevant animal model is lacking, and the molecular mechanisms underlying neurodegeneration are unknown. We found that OPTN C-terminus truncation (OPTN∆C) causes late-onset neurodegeneration of retinal ganglion cells (RGCs), optic nerve (ON), and spinal cord motor neurons, preceded by a striking decrease of axonal mitochondria. Surprisingly, we discover that OPTN directly interacts with both microtubules and the mitochondrial transport complex TRAK1/KIF5B, stabilizing them for proper anterograde axonal mitochondrial transport, in a C-terminus dependent manner. Encouragingly, overexpressing OPTN/TRAK1/KIF5B reverses not only OPTN truncation-induced, but also ocular hypertension-induced neurodegeneration, and promotes striking ON regeneration. Therefore, in addition to generating new animal models for NTG and ALS, our results establish OPTN as a novel facilitator of the microtubule-dependent mitochondrial transport necessary for adequate axonal mitochondria delivery, and its loss as the likely molecular mechanism of neurodegeneration.

    View details for DOI 10.1101/2024.04.02.587832

    View details for PubMedID 38617277

  • Base editing correction of OCRL in Lowe syndrome: ABE-mediated functional rescue in patient-derived fibroblasts. Human molecular genetics Chen, S., Lo, C. H., Liu, Z., Wang, Q., Ning, K., Li, T., Sun, Y. 2024


    Lowe syndrome, a rare X-linked multisystem disorder presenting with major abnormalities in the eyes, kidneys, and central nervous system, is caused by mutations in OCRL gene (NG_008638.1). Encoding an inositol polyphosphate 5-phosphatase, OCRL catalyzes the hydrolysis of PI(4,5)P2 into PI4P. There are no effective targeted treatments for Lowe syndrome. Here, we demonstrate a novel gene therapy for Lowe syndrome in patient fibroblasts using an adenine base editor (ABE) that can efficiently correct pathogenic point mutations. We show that ABE8e-NG-based correction of a disease-causing mutation in a Lowe patient-derived fibroblast line containing R844X mutation in OCRL gene, restores OCRL expression at mRNA and protein levels. It also restores cellular abnormalities that are hallmarks of OCRL dysfunction, including defects in ciliogenesis, microtubule anchoring, α-actinin distribution, and F-actin network. The study indicates that ABE-mediated gene therapy is a feasible treatment for Lowe syndrome, laying the foundation for therapeutic application of ABE in the currently incurable disease.

    View details for DOI 10.1093/hmg/ddae045

    View details for PubMedID 38557732

  • Compartmentalized ciliation changes of oligodendrocytes in aged mouse optic nerve. Journal of neuroscience research Ning, K., Tran, M., Kowal, T. J., Mesentier-Louro, L. A., Sendayen, B. E., Wang, Q., Lo, C. H., Li, T., Majumder, R., Luo, J., Hu, Y., Liao, Y. J., Sun, Y. 2024; 102 (1): e25273


    Primary cilia are microtubule-based sensory organelles that project from the apical surface of most mammalian cells, including oligodendrocytes, which are myelinating cells of the central nervous system (CNS) that support critical axonal function. Dysfunction of CNS glia is associated with aging-related white matter diseases and neurodegeneration, and ciliopathies are known to affect CNS white matter. To investigate age-related changes in ciliary profile, we examined ciliary length and frequency in the retinogeniculate pathway, a white matter tract commonly affected by diseases of aging but in which expression of cilia has not been characterized. We found expression of Arl13b, a marker of primary cilia, in a small group of Olig2-positive oligodendrocytes in the optic nerve, optic chiasm, and optic tract in young and aged C57BL/6 wild-type mice. While the ciliary length and ciliated oligodendrocyte cells were constant in young mice in the retinogeniculate pathway, there was a significant increase in ciliary length in the anterior optic nerve as compared to the aged animals. Morphometric analysis confirmed a specific increase in the ciliation rate of CC1+ /Olig2+ oligodendrocytes in aged mice compared with young mice. Thus, the prevalence of primary cilia in oligodendrocytes in the visual pathway and the age-related changes in ciliation suggest that they may play important roles in white matter and age-associated optic neuropathies.

    View details for DOI 10.1002/jnr.25273

    View details for PubMedID 38284846

  • Crosstalk between the mTOR pathway and primary cilia in human diseases. Current topics in developmental biology Prosseda, P. P., Dannewitz Prosseda, S., Tran, M., Liton, P. B., Sun, Y. 2023; 155: 1-37


    Autophagy is a fundamental catabolic process whereby excessive or damaged cytoplasmic components are degraded through lysosomes to maintain cellular homeostasis. Studies of mTOR signaling have revealed that mTOR controls biomass generation and metabolism by modulating key cellular processes, including protein synthesis and autophagy. Primary cilia, the assembly of which depends on kinesin molecular motors, serve as sensory organelles and signaling platforms. Given these pathways' central role in maintaining cellular and physiological homeostasis, a connection between mTOR and primary cilia signaling is starting to emerge in a variety of diseases. In this review, we highlight recent advances in our understanding of the complex crosstalk between the mTOR pathway and cilia and discuss its function in the context of related diseases.

    View details for DOI 10.1016/bs.ctdb.2023.09.004

    View details for PubMedID 38043949

  • Differential expression of PIEZO1 and PIEZO2 mechanosensitive channels in ocular tissues implicates diverse functional roles. Experimental eye research Zhu, Y., Garcia-Sanchez, J., Dalal, R., Sun, Y., Kapiloff, M. S., Goldberg, J. L., Liu, W. W. 2023: 109675


    PIEZO1 and PIEZO2 are mechanosensitive ion channels that regulate many important physiological processes including vascular blood flow, touch, and proprioception. As the eye is subject to mechanical stress and is highly perfused, these channels may play important roles in ocular function and intraocular pressure regulation. PIEZO channel expression in the eye has not been well defined, in part due to difficulties in validating available antibodies against PIEZO1 and PIEZO2 in ocular tissues. It is also unclear if PIEZO1 and PIEZO2 are differentially expressed. To address these questions, we used single-molecule fluorescence in situ hybridization (smFISH) together with transgenic reporter mice expressing PIEZO fusion proteins under the control of their endogenous promoters to compare the expression and localization of PIEZO1 and PIEZO2 in mouse ocular tissues relevant to glaucoma. We detected both PIEZO1 and PIEZO2 expression in the trabecular meshwork, ciliary body, and in the ganglion cell layer (GCL) of the retina. Piezo1 mRNA was more abundantly expressed than Piezo2 mRNA in these ocular tissues. Piezo1 but not Piezo2 mRNA was detected in the inner nuclear layer and outer nuclear layer of the retina. Our results suggest that PIEZO1 and PIEZO2 are differentially expressed and may have distinct roles as mechanosensors in glaucoma-relevant ocular tissues.

    View details for DOI 10.1016/j.exer.2023.109675

    View details for PubMedID 37820892

  • Unleashing the potential of CRISPR multiplexing: Harnessing Cas12 and Cas13 for precise gene modulation in eye diseases. Vision research Bigini, F., Lee, S. H., Sun, Y. J., Sun, Y., Mahajan, V. B. 2023; 213: 108317


    Gene therapy is a flourishing field with the potential to revolutionize the treatment of genetic diseases. The emergence of CRISPR-Cas9 has significantly advanced targeted and efficient genome editing. Although CRISPR-Cas9 has demonstrated promising potential applications in various genetic disorders, it faces limitations in simultaneously targeting multiple genes. Novel CRISPR systems, such as Cas12 and Cas13, have been developed to overcome these challenges, enabling multiplexing and providing unique advantages. Cas13, in particular, targets mRNA instead of genomic DNA, permitting precise gene expression control and mitigating off-target effects. This review investigates the potential of Cas12 and Cas13 in ocular gene therapy applications, such as suppression of inflammation and cell death. In addition, the capabilities of Cas12 and Cas13 are explored in addressing potential targets related with disease mechanisms such as aberrant isoforms, mitochondrial genes, cis-regulatory sequences, modifier genes, and long non-coding RNAs. Anatomical accessibility and relative immune privilege of the eye provide an ideal organ system for evaluating these novel techniques' efficacy and safety. By targeting multiple genes concurrently, CRISPR-Cas12 and Cas13 systems hold promise for treating a range of ocular disorders, including glaucoma, retinal dystrophies, and age-related macular degeneration. Nonetheless, additional refinement is required to ascertain the safety and efficacy of these approaches in ocular disease treatments. Thus, the development of Cas12 and Cas13 systems marks a significant advancement in gene therapy, offering the potential to devise effective treatments for ocular disorders.

    View details for DOI 10.1016/j.visres.2023.108317

    View details for PubMedID 37722240

  • RGC-specific ATF4 and/or CHOP deletion rescues glaucomatous neurodegeneration and visual function. Molecular therapy. Nucleic acids Fang, F., Liu, P., Huang, H., Feng, X., Li, L., Sun, Y., Kaufman, R. J., Hu, Y. 2023; 33: 286-295


    Endoplasmic reticulum (ER) stress has been linked with various acute and chronic neurodegenerative diseases. We previously found that optic nerve (ON) injury and diseases induce neuronal ER stress in retinal ganglion cells (RGCs). We further demonstrated that germline deletion of CHOP preserves the structure and function of both RGC somata and axons in mouse glaucoma models. Here we report that RGC-specific deletion of CHOP and/or its upstream regulator ATF4 synergistically promotes RGC and ON survival and preserves visual function in mouse ON crush and silicone oil-induced ocular hypertension (SOHU) glaucoma models. Consistently, topical application of the ATF4/CHOP chemical inhibitor ISRIB or RGC-specific CRISPR-mediated knockdown of the ATF4 downstream effector Gadd45a also delivers significant neuroprotection in the SOHU glaucoma model. These studies suggest that blocking the neuronal intrinsic ATF4/CHOP axis of ER stress is a promising neuroprotection strategy for neurodegeneration.

    View details for DOI 10.1016/j.omtn.2023.07.015

    View details for PubMedID 37547290

  • Comparison of Ophthalmologist and Large Language Model Chatbot Responses to Online Patient Eye Care Questions. JAMA network open Bernstein, I. A., Zhang, Y. V., Govil, D., Majid, I., Chang, R. T., Sun, Y., Shue, A., Chou, J. C., Schehlein, E., Christopher, K. L., Groth, S. L., Ludwig, C., Wang, S. Y. 2023; 6 (8): e2330320


    Importance: Large language models (LLMs) like ChatGPT appear capable of performing a variety of tasks, including answering patient eye care questions, but have not yet been evaluated in direct comparison with ophthalmologists. It remains unclear whether LLM-generated advice is accurate, appropriate, and safe for eye patients.Objective: To evaluate the quality of ophthalmology advice generated by an LLM chatbot in comparison with ophthalmologist-written advice.Design, Setting, and Participants: This cross-sectional study used deidentified data from an online medical forum, in which patient questions received responses written by American Academy of Ophthalmology (AAO)-affiliated ophthalmologists. A masked panel of 8 board-certified ophthalmologists were asked to distinguish between answers generated by the ChatGPT chatbot and human answers. Posts were dated between 2007 and 2016; data were accessed January 2023 and analysis was performed between March and May 2023.Main Outcomes and Measures: Identification of chatbot and human answers on a 4-point scale (likely or definitely artificial intelligence [AI] vs likely or definitely human) and evaluation of responses for presence of incorrect information, alignment with perceived consensus in the medical community, likelihood to cause harm, and extent of harm.Results: A total of 200 pairs of user questions and answers by AAO-affiliated ophthalmologists were evaluated. The mean (SD) accuracy for distinguishing between AI and human responses was 61.3% (9.7%). Of 800 evaluations of chatbot-written answers, 168 answers (21.0%) were marked as human-written, while 517 of 800 human-written answers (64.6%) were marked as AI-written. Compared with human answers, chatbot answers were more frequently rated as probably or definitely written by AI (prevalence ratio [PR], 1.72; 95% CI, 1.52-1.93). The likelihood of chatbot answers containing incorrect or inappropriate material was comparable with human answers (PR, 0.92; 95% CI, 0.77-1.10), and did not differ from human answers in terms of likelihood of harm (PR, 0.84; 95% CI, 0.67-1.07) nor extent of harm (PR, 0.99; 95% CI, 0.80-1.22).Conclusions and Relevance: In this cross-sectional study of human-written and AI-generated responses to 200 eye care questions from an online advice forum, a chatbot appeared capable of responding to long user-written eye health posts and largely generated appropriate responses that did not differ significantly from ophthalmologist-written responses in terms of incorrect information, likelihood of harm, extent of harm, or deviation from ophthalmologist community standards. Additional research is needed to assess patient attitudes toward LLM-augmented ophthalmologists vs fully autonomous AI content generation, to evaluate clarity and acceptability of LLM-generated answers from the patient perspective, to test the performance of LLMs in a greater variety of clinical contexts, and to determine an optimal manner of utilizing LLMs that is ethical and minimizes harm.

    View details for DOI 10.1001/jamanetworkopen.2023.30320

    View details for PubMedID 37606922

  • Shear stress induces autophagy in Schlemm's canal cells via primary cilia-mediated SMAD2/3 signaling pathway. Autophagy reports Shim, M. S., Dixon, A., Nettesheim, A., Perkumas, K. M., Stamer, W. D., Sun, Y., Liton, P. B. 2023; 2 (1)


    The Schlemm's canal (SC) is a circular, lymphatic-like vessel located at the limbus of the eye that participates in the regulation of aqueous humor drainage to control intraocular pressure (IOP). Circumferential flow of aqueous humor within the SC lumen generates shear stress, which regulates SC cell behaviour. Using biochemical analysis and real-time live cell imaging techniques, we have investigated the activation of autophagy in SC cells by shear stress. We report, for the first time, the primary cilium (PC)-dependent activation of autophagy in SC cells in response to shear stress. Moreover, we identified PC-dependent shear stress-induced autophagy to be positively regulated by phosphorylation of SMAD2 in its linker and C-terminal regions. Additionally, SMAD2/3 signaling was found to transcriptionally activate LC3B, ATG5 and ATG7 in SC cells. Intriguingly, concomitant to SMAD2-dependent activation of autophagy, we also report here the activation of mTOR pathway, a classical autophagy inhibitor, in SC cells by shear stress. mTOR activation was found to also be dependent on the PC. Moreover, pharmacological inhibition of class I PI3K increased phosphorylation of SMAD2 at the linker and activated autophagy. Together, our data indicates an interplay between PI3K and SMAD2/3 signaling pathways in the regulation of PC-dependent shear stress-induced autophagy in SC cells.

    View details for DOI 10.1080/27694127.2023.2236519

    View details for PubMedID 37637387

    View details for PubMedCentralID PMC10448710

  • Differential effects of SARM1 inhibition in traumatic glaucoma and EAE optic neuropathies. Molecular therapy. Nucleic acids Liu, P., Chen, W., Jiang, H., Huang, H., Liu, L., Fang, F., Li, L., Feng, X., Liu, D., Dalal, R., Sun, Y., Jafar-Nejad, P., Ling, K., Rigo, F., Ye, J., Hu, Y. 2023; 32: 13-27


    Optic neuropathy is a group of optic nerve (ON) diseases withprogressive degeneration of ON and retinal ganglion cells(RGCs). The lack of neuroprotective treatments is a central challenge for this leading cause of irreversible blindness. SARM1 (sterile alpha and TIR motif-containing protein 1) has intrinsic nicotinamide adenine dinucleotide (NAD+) hydrolase activity that causes axon degeneration by degrading axonal NAD+ significantly after activation by axon injury. SARM1 deletion is neuroprotective in many, but not all, neurodegenerative disease models. Here, we compare two therapy strategies for SARM1 inhibition, antisense oligonucleotide (ASO) and CRISPR, with germline SARM1 deletion in the neuroprotection of three optic neuropathy mouse models. This study reveals that, similar to germline SARM1 knockout in every cell, local retinal SARM1 ASO delivery and adeno-associated virus (AAV)-mediated RGC-specific CRISPR knockdown of SARM1 provide comparable neuroprotection to both RGC somata and axons in the silicone oil-induced ocular hypertension (SOHU) glaucoma model but only protect RGC axons, not somata, after traumatic ON injury. Surprisingly, neither of these two therapy strategies of SARM1 inhibition nor SARM1 germline knockout (KO) benefits RGC or ON survival in the experimental autoimmune encephalomyelitis (EAE)/optic neuritis model. Our studies therefore suggest that SARM1 inhibition by local ASO delivery or AAV-mediated CRISPR is a promising neuroprotective gene therapy strategy for traumatic and glaucomatous optic neuropathies but not for demyelinating optic neuritis.

    View details for DOI 10.1016/j.omtn.2023.02.029

    View details for PubMedID 36950280

  • Hardwiring tissue-specific AAV transduction in mice through engineered receptor expression. Nature methods Zengel, J., Wang, Y. X., Seo, J. W., Ning, K., Hamilton, J. N., Wu, B., Raie, M., Holbrook, C., Su, S., Clements, D. R., Pillay, S., Puschnik, A. S., Winslow, M. M., Idoyaga, J., Nagamine, C. M., Sun, Y., Mahajan, V. B., Ferrara, K. W., Blau, H. M., Carette, J. E. 2023


    The development of transgenic mouse models that express genes of interest in specific cell types has transformed our understanding of basic biology and disease. However, generating these models is time- and resource-intensive. Here we describe a model system, SELective Expression and Controlled Transduction In Vivo (SELECTIV), that enables efficient and specific expression of transgenes by coupling adeno-associated virus (AAV) vectors with Cre-inducible overexpression of the multi-serotype AAV receptor, AAVR. We demonstrate that transgenic AAVR overexpression greatly increases the efficiency of transduction of many diverse cell types, including muscle stem cells, which are normally refractory to AAV transduction. Superior specificity is achieved by combining Cre-mediated AAVR overexpression with whole-body knockout of endogenous Aavr, which is demonstrated in heart cardiomyocytes, liver hepatocytes and cholinergic neurons. The enhanced efficacy and exquisite specificity of SELECTIV has broad utility in development of new mouse model systems and expands the use of AAV for gene delivery in vivo.

    View details for DOI 10.1038/s41592-023-01896-x

    View details for PubMedID 37291262

    View details for PubMedCentralID 3337962

  • Effect of Brimonidine on Retinal Ganglion Cell Function by in vivo Calcium Imaging in Glaucoma Mice Model Li, T., Wang, Q., Lo, C., Ning, K., Majumder, R., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2023
  • Safety and Target Engagement of Complement C1q Inhibitor ANX007 in Neurodegenerative Eye Disease: Results from Phase I Studies in Glaucoma. Ophthalmology science Sun, Y., Wirta, D., Murahashi, W., Mathur, V., Sankaranarayanan, S., Taylor, L. K., Yednock, T., Fong, D. S., Goldberg, J. L. 2023; 3 (2): 100290


    Complement C1q, the initiating molecule of the classical complement cascade, is involved in synapse elimination and neuronal loss in neurodegenerative diseases including glaucoma. Here we report an evaluation of the safety, tolerability, and ocular pharmacokinetics (PK) and pharmacodynamics of intravitreal (IVT) injections of ANX007, an anti-C1q monoclonal antibody fragment that blocks activation of the classical complement cascade.An open-label, single-dose-escalation phase Ia study followed by a double-masked, randomized, sham-controlled, repeat-injection phase Ib study.A total of 26 patients with primary open-angle glaucoma.Nine patients with primary open-angle glaucoma (mean Humphrey visual field deviation between -3 and -18 decibels [dB]) were enrolled in phase Ia and received single doses of ANX007 (1.0 mg, n = 3; 2.5 mg, n = 3; or 5.0 mg, n = 3). Seventeen patients (mean Humphrey visual field deviation between -3 and -24 dB) were enrolled in phase Ib and randomized to 2 monthly doses of ANX007 (sham, n = 6; 2.5 mg ANX007, n = 6; or 5 mg ANX007, n = 5).Safety and tolerability (including laboratory evaluation of urinalysis, complete blood count, and serum chemistries), ANX007 PK, target engagement, and immunogenicity.The mean age overall was 70 years in phase Ia and 68 years in phase Ib. In both studies, no serious adverse events were observed, no non-ocular treatment-emergent adverse events (TEAEs) attributable to study drug were reported, and ocular TEAEs were mild. Intraocular pressure returned to normal levels for all patients within 45 minutes of IVT injection. No clinically significant deviations in laboratory results were observed. In the phase Ib study, C1q in the aqueous humor was reduced to undetectable levels in both the 2.5 mg and 5 mg cohorts 4 weeks after the first ANX007 dose.In these studies, single and repeat IVT ANX007 injections were well tolerated and demonstrated full target engagement 4 weeks after dosing with both low and high doses, supporting monthly or less-frequent dosing. Further investigation in neurodegenerative ocular diseases is warranted.Proprietary or commercial disclosure may be found after the references.

    View details for DOI 10.1016/j.xops.2023.100290

    View details for PubMedID 37124168

    View details for PubMedCentralID PMC10130689

  • Schlemm's canal cell induces autophagy in response to shear stress via primary cilia-mediated SMAD2/3 signaling pathway Sim, M., Dixon, A., Nettesheim, A., Perkumas, K., Stamer, W., Sun, Y., Liton, P. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2023
  • Cilia-associated wound repair mediated by IFT88 in retinal pigment epithelium. Scientific reports Ning, K., Bhuckory, M. B., Lo, C. H., Sendayen, B. E., Kowal, T. J., Chen, M., Bansal, R., Chang, K. C., Vollrath, D., Berbari, N. F., Mahajan, V. B., Hu, Y., Sun, Y. 2023; 13 (1): 8205


    Primary cilia are conserved organelles that integrate extracellular cues into intracellular signals and are critical for diverse processes, including cellular development and repair responses. Deficits in ciliary function cause multisystemic human diseases known as ciliopathies. In the eye, atrophy of the retinal pigment epithelium (RPE) is a common feature of many ciliopathies. However, the roles of RPE cilia in vivo remain poorly understood. In this study, we first found that mouse RPE cells only transiently form primary cilia. We then examined the RPE in the mouse model of Bardet-Biedl Syndrome 4 (BBS4), a ciliopathy associated with retinal degeneration in humans, and found that ciliation in BBS4 mutant RPE cells is disrupted early during development. Next, using a laser-induced injury model in vivo, we found that primary cilia in RPE reassemble in response to laser injury during RPE wound healing and then rapidly disassemble after the repair is completed. Finally, we demonstrated that RPE-specific depletion of primary cilia in a conditional mouse model of cilia loss promoted wound healing and enhanced cell proliferation. In summary, our data suggest that RPE cilia contribute to both retinal development and repair and provide insights into potential therapeutic targets for more common RPE degenerative diseases.

    View details for DOI 10.1038/s41598-023-35099-3

    View details for PubMedID 37211572

    View details for PubMedCentralID 6513937

  • Glaucoma and Myopia: Diagnostic Challenges. Biomolecules Sun, M. T., Tran, M., Singh, K., Chang, R., Wang, H., Sun, Y. 2023; 13 (3)


    The rising global prevalence of myopia is a growing concern for clinicians, as it predisposes patients to severe ocular pathologies including glaucoma. High myopia can be associated with clinical features that resemble glaucomatous damage, which make an accurate glaucoma diagnosis challenging, particularly among patients with normal intraocular pressures. These patients may also present with established visual field defects which can mimic glaucoma, and standard imaging technology is less useful in disease detection and monitoring due to the lack of normative data for these anatomically unique eyes. Progression over time remains the most critical factor in facilitating the detection of early glaucomatous changes, and thus careful longitudinal follow-up of high-risk myopic patients is the most important aspect of management. Here, we review our current understanding of the complex relationship between myopia and glaucoma, and the diagnostic challenges and limitations of current testing protocols including visual field, intraocular pressure, and imaging. Furthermore, we discuss the clinical findings of two highly myopic patients with suspected glaucoma.

    View details for DOI 10.3390/biom13030562

    View details for PubMedID 36979497

  • Gonioscopy-assisted transluminal trabeculotomy for open-angle glaucoma with failed incisional glaucoma surgery: two-year results. BMC ophthalmology Wang, Y., Zhang, W., Xin, C., Sang, J., Sun, Y., Wang, H. 2023; 23 (1): 89


    To evaluate the safety and efficacy of gonioscopy-assisted transluminal trabeculotomy (GATT) in treating patients with open-angle glaucoma (OAG) who had failed prior incisional glaucoma surgery.A consecutive case series of OAG patients aged ≥ 18 who underwent GATT with previous failed glaucoma incision surgery was retrospectively analyzed. Main outcome measures included intraocular pressure (IOP), the number of glaucoma medications, surgical success rate, and occurrence of complications. Success was defined as an IOP of ≤ 21 mmHg and a reduction of IOP by 20% or more from baseline with (qualified success) or without (complete success) glaucoma medications. For eyes with preoperative IOP of < 21 mmHg on 3 or 4 glaucoma medications, postoperative IOP of ≤ 18 mmHg without any glaucoma medications was also defined as complete success.Forty-four eyes of 35 patients (21 with juvenile-onset open-angle glaucoma and 14 with adult-onset primary open-angle glaucoma) with a median age of 38 years were included in this study. The proportion of eyes with 1 prior incisional glaucoma surgery was 79.5%, and the others had 2 prior surgeries. IOP decreased from 27.4 ± 8.8 mm Hg on 3.6 ± 0.7 medications preoperatively to 15.3 ± 2.7 mm Hg on 0.5 ± 0.9 medications at the 24-month visit (P < 0.001). The mean IOP and the number of glaucoma medications at each follow-up visit were lower than the baseline (all P < 0.001). At 24 months postoperatively, 82.1% of the eyes had IOP ≤ 18 mmHg (versus 15.9% preoperatively, P < 0.001), 56.4% reached IOP ≤ 15 mmHg (versus 4.6% preoperatively, P < 0.001), and 15.4% achieved IOP ≤ 12 mmHg (compared to none preoperatively, P = 0.009). While 95.5% of eyes took 3 or more medications preoperatively, 66.7% did not take glaucoma medication 24 months after GATT. Thirty-four (77.3%) eyes achieved IOP reduction greater than 20% on fewer medications. The complete and qualified success rates were 60.9% and 84.1%, respectively. No vision-threatening complications occurred.GATT was safe and effective in treating refractory OAG patients who failed prior incisional glaucoma surgery.

    View details for DOI 10.1186/s12886-023-02830-7

    View details for PubMedID 36879233

    View details for PubMedCentralID PMC9987149

  • Influence of Age, Gender, and Wait-Times On Public Online Ratings of Glaucoma Physicians in the United States. Journal of glaucoma Kim, J. Y., Francisco, R., Wang, J., Liu, J. J., Stephenson, N. J., Khalil, C. B., Kim, D. H., Nguyen, A. X., Youn, G. M., Sun, Y., Wu, A. Y. 2023


    PRCIS: Glaucoma surgeons are highly rated by the general public. Physicians with shorter wait times and who are younger are more likely to have higher ratings. Women glaucoma physicians are less likely to have higher ratings.PURPOSE: Find what characteristics of glaucoma physicians are associated with higher online ratings.PATENTS AND METHODS: All American members of the American Glaucoma Society (AGS) were queried on Healthgrades, Vitals, and Yelp. Ratings, medical school ranking, region of practice, gender, age, and wait times were recorded.RESULTS: 1106 (78.2%) of AGS members had at least one review across the three platforms. The average score among glaucoma surgeons was 4.160 (0.898 standard deviation, SD). Women physicians were associated with lower online ratings (adjusted odds ratio [aOR] 0.536 [95% CI 0.354-0.808). Physicians with less than 30 minutes of wait time had higher ratings: 15-30 minutes wait time (aOR 2.273 [95% CI 1.430-3.636]) and <15-minute wait time (aOR 3.102 [95% CI 1.888-5.146]). Older physicians had lower ratings (aOR 0.384 [95% CI 0.255-0.572]).CONCLUSIONS: Public online ratings of glaucoma specialists in the United States appear to favour those of younger age, men, and those with shorter wait times.

    View details for DOI 10.1097/IJG.0000000000002189

    View details for PubMedID 36795534

  • Characterization of Primary Cilia Formation in Human ESC-Derived Retinal Organoids. Stem cells international Ning, K., Luo, Z., Kowal, T. J., Tran, M., Majumder, R., Jarin, T. M., Wu, A. Y., Goldberg, J. L., Sun, Y. 2023; 2023: 6494486


    Objectives: Primary cilia are conserved organelles found in polarized mammalian cells that regulate neuronal growth, migration, and differentiation. Proper cilia formation is essential during eye development. Our previous reports found that both amacrine and retinal ganglion cells (RGCs) contain primary cilia in primate and rodent retinas. However, whether primary cilia are present in the inner retina of human retinal organoids remains unknown. The purpose of this study is to characterize the primary cilia distribution in human embryonic stem cell (hESC-derived retinal organoid development.Materials and Methods: Retinal organoids were differentiated from a hESC line, harvested at various developmental timepoints (day 44-day 266), and immunostained with antibodies for primary cilia, including Arl13b (for the axoneme), AC3, and Centrin3 (for the basal body). AP2alpha, Prox1, GAD67, Calretinin, GFAP, PKCalpha, and Chx10 antibodies as well as Brn3b-promoted tdTomato expression were used to visualize retinal cell types.Results: A group of ciliated cells were present in the inner aspects of retinal organoids from day 44 to day 266 in culture. Ciliated Chx10-positive retinal progenitor cells, GFAP-positive astrocytes, and PKCalpha-positive rod-bipolar cells were detected later during development (day 176 to day 266). Ciliation persisted during all stages of retinal developmental in AP2alpha-positive amacrine cells, but it was decreased in Brn3b-positive retinal ganglion cells (RGCs) at later time points. Additionally, AC3-positive astrocytes significantly decreased during the later stages of organoid formation.Conclusions: Amacrine cells in retinal organoids retain cilia throughout development, whereas RGC ciliation gradually and progressively decreases with organoid maturation.

    View details for DOI 10.1155/2023/6494486

    View details for PubMedID 36684387

  • Cellular and subcellular optogenetic approaches towards neuroprotection and vision restoration. Progress in retinal and eye research Wood, E. H., Kreymerman, A., Kowal, T., Buickians, D., Sun, Y., Muscat, S., Mercola, M., Moshfeghi, D. M., Goldberg, J. L. 2022: 101153


    Optogenetics is defined as the combination of genetic and optical methods to induce or inhibit well-defined events in isolated cells, tissues, or animals. While optogenetics within ophthalmology has been primarily applied towards treating inherited retinal disease, there are a myriad of other applications that hold great promise for a variety of eye diseases including cellular regeneration, modulation of mitochondria and metabolism, regulation of intraocular pressure, and pain control. Supported by primary data from the authors' work with in vitro and in vivo applications, we introduce a novel approach to metabolic regulation, Opsins to Restore Cellular ATP (ORCA). We review the fundamental constructs for ophthalmic optogenetics, present current therapeutic approaches and clinical trials, and discuss the future of subcellular and signaling pathway applications for neuroprotection and vision restoration.

    View details for DOI 10.1016/j.preteyeres.2022.101153

    View details for PubMedID 36503723

  • Longitudinal in vivo Ca2+ imaging reveals dynamic activity changes of diseased retinal ganglion cells at the single-cell level. Proceedings of the National Academy of Sciences of the United States of America Li, L., Feng, X., Fang, F., Miller, D. A., Zhang, S., Zhuang, P., Huang, H., Liu, P., Liu, J., Sredar, N., Liu, L., Sun, Y., Duan, X., Goldberg, J. L., Zhang, H. F., Hu, Y. 2022; 119 (48): e2206829119


    Retinal ganglion cells (RGCs) are heterogeneous projection neurons that convey distinct visual features from the retina to brain. Here, we present a high-throughput in vivo RGC activity assay in response to light stimulation using noninvasive Ca2+ imaging of thousands of RGCs simultaneously in living mice. Population and single-cell analyses of longitudinal RGC Ca2+ imaging reveal distinct functional responses of RGCs and unprecedented individual RGC activity conversions during traumatic and glaucomatous degeneration. This study establishes a foundation for future in vivo RGC function classifications and longitudinal activity evaluations using more advanced imaging techniques and visual stimuli under normal, disease, and neural repair conditions. These analyses can be performed at both the population and single-cell levels using temporal and spatial information, which will be invaluable for understanding RGC pathophysiology and identifying functional biomarkers for diverse optic neuropathies.

    View details for DOI 10.1073/pnas.2206829119

    View details for PubMedID 36409915

  • Epigenetics in glaucoma: a link between DNA methylation and neurodegeneration. The Journal of clinical investigation Liu, W. W., Sun, Y. 2022; 132 (21)


    Normal-tension glaucoma is a form of optic nerve degeneration that is characterized by loss of retinal ganglion cells independent of eye pressure elevation. In this issue of the JCI, Pan et al. report the discovery in a Japanese family of a mutation in the METTL23 gene, which encodes a DNA methyltransferase that causes normal-pressure glaucoma in haploinsufficiency. Inherited as an autosomal dominant condition, METTL23 deficiency revealed an important function in the regulation of pS2 and the downstream NF-kappaB signaling pathway, which has previously been linked to glaucomatous optic nerve degeneration. These findings are the first direct link between defective epigenetic regulatory machinery and genetic forms of optic nerve degeneration.

    View details for DOI 10.1172/JCI163670

    View details for PubMedID 36317630

  • Clinical characteristics of high myopia in female carriers of pathogenic RPGR mutations: a case series and review of the literature. Ophthalmic genetics Tran, M., Kolesnikova, M., Kim, A. H., Kowal, T., Ning, K., Mahajan, V. B., Tsang, S. H., Sun, Y. 2022: 1-9


    BACKGROUND: RPGR mutations are the most common cause of X-linked retinitis pigmentosa (XLRP). High myopia has been described as a very frequent feature among affected female carriers of XLRP. However, the clinical phenotype of female patients presenting with X-linked RPGR-related high myopia has not been well described.MATERIALS AND METHODS: Retrospective case series of four female patients with RPGR mutations and a diagnosis of high myopia, who presented to two academic eye centers. Clinical data, including age, family history, visual acuity, refractive error, dilated fundus exam, fundus photography, optical coherence tomography, electroretinography, and results of genetic testing, were collected.RESULTS: Three RPGR variants identified in the present study have not been previously associated with myopia in female carriers. One variant (c.2405_2406delAG, p.Glu802Glyfs *32) has been previously associated with a myopic phenotype in a female patient. Patients became symptomatic between the first and sixth decades of life. Myopia-associated tilted optic discs and posterior staphyloma were present in all patients. Two patients presented with intraretinal migration of the retinal pigment epithelium.CONCLUSION: RPGR-related high myopia has been associated with mutations in exons 1-14 and ORF15 in heterozygous females. There is a wide range of visual function among carriers. Although the exact mechanism of RPGR-related high myopia is still unclear, continued molecular diagnosis and description of phenotypes remain a crucial step in understanding the impact of RPGR mutations on visual function in female XLRP carriers.

    View details for DOI 10.1080/13816810.2022.2113544

    View details for PubMedID 36017691

  • Structural and Metabolic Imaging after Short-term Use of the Balance Goggles System in Glaucoma Patients: A Pilot Study. Journal of glaucoma Sun, M. T., Beykin, G., Lee, W. S., Sun, Y., Chang, R., Nunez, M., Li, K. Z., Knasel, C., Rich, C., Goldberg, J. L. 2022


    Short-term use of the Balance Goggles System in glaucoma patients was not associated with observable changes in conventional OCT imaging but metabolic imaging using peripapillary flavoprotein fluorescence may represent a useful adjuctive investigation.To determine whether the intraocular pressure (IOP)-lowering effects of the Balance Goggles System (BGS) are accompanied by changes in retinal thickness measured by ocular coherence tomography, retinal vascular density measured by OCT-angiography, or novel peripapillary metabolic profiling using flavoprotein fluorescence (FPF) measured by a fundus camera.Prospective comparative case-series.8 eyes from 8 patients with open-angle glaucoma ranging from mild to severe.In this prospective, single-center, open-label, non-randomized, single-arm study patients received a baseline evaluation including retinal imaging, then one hour of negative pressure application through the BGS, followed by repeat retinal imaging. Participants then used the BGS at home for 1 month and underwent a repeat evaluation at the conclusion of the trial.Changes in nerve fiber layer thickness, OCTA vascular parameters and FPF scores.Mean baseline IOP was 18.0±3.1 mmHg and there was no significant change in IOP at follow-up. At 1 month compared to baseline, there was a statistically significant improvement in FPF optic nerve head rim scores (12.7±11.6 to 10.5±7.5; P=0.04). Additionally, there was there was a trend towards an increase in RNFL thickness after 1 month (69.5±14.2 to 72.0±13.7; P=0.1), but there were no statistically significant differences observable with any of the OCTA vascular parameters either at 1 hour or after 1 month.There were no significant changes observable using conventional OCT imaging following short-term use of the BGS, although metabolic imaging using FPF may be a useful potential biomarker to complement existing investigations. Additional studies are warranted to further investigate these changes.

    View details for DOI 10.1097/IJG.0000000000002066

    View details for PubMedID 35696700

  • Loss of Cilia in Uveal Melanoma: Implications for Diagnosis Heiferman, M., Ning, K., Song, E., Kowal, T., Dryden, I., Tran, M., Dalal, R., Chu, P., Mruthyunjaya, P., Lin, J., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • Neuroprotection of SARM1 Inhibition in Traumatic and Glaucomatous but not in EAE Optic Neuropathies Liu, P., Huang, H., Chen, W., Fang, F., Li, L., Feng, X., Liu, L., Liu, D., Dalal, R., Sun, Y., Ling, K., Rigo, F., Hu, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • Defective Microtubule-Based Transporters Alter Basal mTORC1 And Akt Signaling in Lowe Syndrome Patient-Derived Cells Wang, Q., Wang, B., Kowal, T., Hu, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • Differences in primary cilia amongst retinal ganglion cell subtypes Kowal, T., Dhande, O., Ning, K., Wang, B., Wang, Q., Liu, W., Berbari, N., Hu, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • In Vivo Evaluation of Naive and Diseased RGC Activities at Single-Cell Level Li, L., Fang, F., Feng, X., Zhang, S., Miller, D., Zhuang, P., Huang, H., Liu, P., Liu, J., Sredar, N., Liu, L., Sun, Y., Duan, X., Goldberg, J. L., Zhang, H., Hu, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • Increased ciliary length of oligodendrocytes in anterior optic nerve with ageing Tran, M., Ning, K., Kowal, T., Majumder, R., Wang, Q., Hu, Y., Liao, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • Age-Associated Changes in Astrocytes Cilia of Mouse Retina and Optic Nerve Majumder, R., Ning, K., Kowal, T., Wang, Q., Tran, M., Wang, B., Hu, Y., Liao, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • IFT88 Mediates Cilia-Associated Wound Repair in Retinal Pigment Epithelium Ning, K., Bhuckory, M., Kowal, T., Chen, M., Bansal, R., Palanker, D. V., Vollrath, D., Berbari, N., Mahajan, V. B., Hu, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
  • Distribution of prototypical primary cilia markers in subtypes of retinal ganglion cells. The Journal of comparative neurology Kowal, T. J., Dhande, O. S., Wang, B., Wang, Q., Ning, K., Liu, W., Berbari, N. F., Hu, Y., Sun, Y. 2022


    Loss of retinal ganglion cells (RGCs) underlies several forms of retinal disease including glaucomatous optic neuropathy, a leading cause of irreversible blindness. Several rare genetic disorders associated with cilia dysfunction have retinal degeneration as a clinical hallmark. Much of the focus of ciliopathy associated blindness is on the connecting cilium of photoreceptors; however, RGCs also possess primary cilia. It is unclear what roles RGC cilia play, what proteins and signaling machinery localize to RGC cilia, or how RGC cilia are differentiated across the subtypes of RGCs. To better understand these questions, we assessed the presence or absence of a prototypical cilia marker Arl13b and a widely distributed neuronal cilia marker AC3 in different subtypes of mouse RGCs. Interestingly, not all RGC subtype cilia are the same and there are significant differences even among these standard cilia markers. Alpha-RGCs positive for osteopontin, calretinin, and SMI32 primarily possess AC3-positive cilia. Directionally selective RGCs that are CART positive or Trhr positive localize either Arl13b or AC3, respectively, in cilia. Intrinsically photosensitive RGCs differentially localize Arl13b and AC3 based on melanopsin expression. Taken together, we characterized the localization of gold standard cilia markers in different subtypes of RGCs and conclude that cilia within RGC subtypes may be differentially organized. Future studies aimed at understanding RGC cilia function will require a fundamental ability to observe the cilia across subtypes as their signaling protein composition is elucidated. A comprehensive understanding of RGC cilia may reveal opportunities to understanding how their dysfunction leads to retinal degeneration.

    View details for DOI 10.1002/cne.25326

    View details for PubMedID 35434813

  • Advances in Ophthalmic Optogenetics: Approaches and Applications. Biomolecules Prosseda, P. P., Tran, M., Kowal, T., Wang, B., Sun, Y. 2022; 12 (2)


    Recent advances in optogenetics hold promise for vision restoration in degenerative eye diseases. Optogenetics refers to techniques that use light to control the cellular activity of targeted cells. Although optogenetics is a relatively new technology, multiple therapeutic options are already being explored in pre-clinical and phase I/II clinical trials with the aim of developing novel, safe, and effective treatments for major blinding eye diseases, such as glaucoma and retinitis pigmentosa. Optogenetic approaches to visual restoration are primarily aimed at replacing lost or dysfunctional photoreceptors by inserting light-sensitive proteins into downstream retinal neurons that have no intrinsic light sensitivity. Such approaches are attractive because they are agnostic to the genetic causes of retinal degeneration, which raises hopes that all forms of retinal dystrophic and degenerative diseases could become treatable. Optogenetic strategies can also have a far-reaching impact on translational research by serving as important tools to study the pathogenesis of retinal degeneration and to identify clinically relevant therapeutic targets. For example, the CRY-CIBN optogenetic system has been recently applied to animal models of glaucoma, suggesting a potential role of OCRL in the regulation of intraocular pressure in trabecular meshwork. As optogenetic strategies are being intensely investigated, it appears crucial to consider the opportunities and challenges such therapies may offer. Here, we review the more recent promising optogenetic molecules, vectors, and applications of optogenetics for the treatment of retinal degeneration and glaucoma. We also summarize the preliminary results of ongoing clinical trials for visual restoration.

    View details for DOI 10.3390/biom12020269

    View details for PubMedID 35204770

  • Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms. Investigative ophthalmology & visual science McDowell, C. M., Kizhatil, K., Elliott, M. H., Overby, D. R., van Batenburg-Sherwood, J., Millar, J. C., Kuehn, M. H., Zode, G., Acott, T. S., Anderson, M. G., Bhattacharya, S. K., Bertrand, J. A., Borras, T., Bovenkamp, D. E., Cheng, L., Danias, J., De Ieso, M. L., Du, Y., Faralli, J. A., Fuchshofer, R., Ganapathy, P. S., Gong, H., Herberg, S., Hernandez, H., Humphries, P., John, S. W., Kaufman, P. L., Keller, K. E., Kelley, M. J., Kelly, R. A., Krizaj, D., Kumar, A., Leonard, B. C., Lieberman, R. L., Liton, P., Liu, Y., Liu, K. C., Lopez, N. N., Mao, W., Mavlyutov, T., McDonnell, F., McLellan, G. J., Mzyk, P., Nartey, A., Pasquale, L. R., Patel, G. C., Pattabiraman, P. P., Peters, D. M., Raghunathan, V., Rao, P. V., Rayana, N., Raychaudhuri, U., Reina-Torres, E., Ren, R., Rhee, D., Chowdhury, U. R., Samples, J. R., Samples, E. G., Sharif, N., Schuman, J. S., Sheffield, V. C., Stevenson, C. H., Soundararajan, A., Subramanian, P., Sugali, C. K., Sun, Y., Toris, C. B., Torrejon, K. Y., Vahabikashi, A., Vranka, J. A., Wang, T., Willoughby, C. E., Xin, C., Yun, H., Zhang, H. F., Fautsch, M. P., Tamm, E. R., Clark, A. F., Ethier, C. R., Stamer, W. D. 2022; 63 (2): 12


    Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.

    View details for DOI 10.1167/iovs.63.2.12

    View details for PubMedID 35129590

  • NMNAT2 Is Downregulated in Glaucomatous RGCs and RGC-Specific Gene Therapy Rescues Neurodegeneration and Visual Function. Molecular therapy : the journal of the American Society of Gene Therapy Fang, F., Zhuang, P., Feng, X., Liu, P., Liu, D., Huang, H., Li, L., Chen, W., Liu, L., Sun, Y., Jiang, H., Ye, J., Hu, Y. 1800


    The lack of neuroprotective treatments for retinal ganglion cells (RGCs) and optic nerve (ON) is a central challenge for glaucoma management. Emerging evidence suggests that redox factor NAD+ decline is a hallmark of aging and neurodegenerative diseases. Supplementation with NAD+ precursors and overexpression of NMNAT1, the key enzyme in the NAD+ biosynthetic process, have significant neuroprotective effects. We first profile the translatomes of RGCs in naive mice and mice with silicone oil-induced ocular hypertension (SOHU)/glaucoma by RiboTag mRNA sequencing. Intriguingly, only NMNAT2, but not NMNAT1 or NMNAT3, is significantly decreased in SOHU glaucomatous RGCs, which we confirm by in situ hybridization. We next demonstrate that AAV2 intravitreal injection-mediated overexpression of long half-life NMNAT2 mutant driven by RGC-specific mouse gamma-synuclein (mSncg) promoter restores decreased NAD+ levels in glaucomatous RGCs and ONs. Moreover, this RGC-specific gene therapy strategy delivers significant neuroprotection of both RGC soma and axon and preservation of visual function in the traumatic ON crush model and the SOHU glaucoma model. Collectively, our studies suggest that the weakening of NMNAT2 expression in glaucomatous RGCs contributes to a deleterious NAD+ decline and that modulating RGC intrinsic NMNAT2 levels by AAV2-mSncg vector is a promising gene therapy for glaucomatous neurodegeneration.

    View details for DOI 10.1016/j.ymthe.2022.01.035

    View details for PubMedID 35114390

  • Drug delivery to the anterior segment of the eye: a review of current and future treatment strategies. International journal of pharmaceutics Mofidfar, M., Abdi, B., Ahadian, S., Mostafavi, E., Desai, T. A., Abbasi, F., Sun, Y., Manche, E. E., Ta, C. N., Flowers, C. W. 2021: 120924


    Research in the development of ophthalmic drug formulations and innovative technologies over the past few decades has been directed at improving the penetration of medications delivered to the eye. Currently, approximately 90% of all ophthalmic drug formulations (e.g. liposomes, micelles) are applied as eye drops. The major challenge of topical eye drops is low bioavailability, need for frequent instillation due to the short half-life, poor drug solubility, and potential side effects. Recent research has been focused on improving topical drug delivery devices by increasing ocular residence time, overcoming physiological and anatomical barriers, and developing medical devices and drug formulations to increase the duration of action of the active drugs. Researchers have developed innovative technologies and formulations ranging from sub-micron to macroscopic size such as prodrugs, enhancers, mucus-penetrating particles (MPPs), therapeutic contact lenses, and collagen corneal shields. Another approach towards the development of effective topical drug delivery is embedding therapeutic formulations in microdevices designed for sustained release of the active drugs. The goal is to optimize the delivery of ophthalmic medications by achieving high drug concentration with prolonged duration of action that is convenient for patients to administer.

    View details for DOI 10.1016/j.ijpharm.2021.120924

    View details for PubMedID 34324989

  • Primary Cilia in Amacrine Cells in Retinal Development. Investigative ophthalmology & visual science Ning, K., Sendayen, B. E., Kowal, T. J., Wang, B., Jones, B. W., Hu, Y., Sun, Y. 2021; 62 (9): 15


    Purpose: Primary cilia are conserved organelles found in polarized cells within the eye that regulate cell growth, migration, and differentiation. Although the role of cilia in photoreceptors is well-studied, the formation of cilia in other retinal cell types has received little attention. In this study, we examined the ciliary profile focused on the inner nuclear layer of retinas in mice and rhesus macaque primates.Methods: Retinal sections or flatmounts from Arl13b-Cetn2 tg transgenic mice were immunostained for cell markers (Pax6, Sox9, Chx10, Calbindin, Calretinin, ChaT, GAD67, Prox1, TH, and vGluT3) and analyzed by confocal microscopy. Primate retinal sections were immunostained for ciliary and cell markers (Pax6 and Arl13b). Optical coherence tomography (OCT) and ERGs were used to assess visual function of Vift88 mice.Results: During different stages of mouse postnatal eye development, we found that cilia are present in Pax6-positive amacrine cells, which were also observed in primate retinas. The cilia of subtypes of amacrine cells in mice were shown by immunostaining and electron microscopy. We also removed primary cilia from vGluT3 amacrine cells in mouse and found no significant vision defects. In addition, cilia were present in the outer limiting membrane, suggesting that a population of Muller glial cells forms cilia.Conclusions: We report that several subpopulations of amacrine cells in inner nuclear layers of the retina form cilia during early retinal development in mice and primates.

    View details for DOI 10.1167/iovs.62.9.15

    View details for PubMedID 34241625

  • Gender Gap in the Award Recipients of the Association for Research in Vision and Ophthalmology Ratan, S., Anne Xuan-Lan Nguyen, Biyani, A., Trinh, X., Sun, Y., Saleh, S., Wu, A. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2021
  • OCRL regulates lysosome positioning and mTORC1 activity through SSX2IP-mediated microtubule anchoring. EMBO reports Wang, B., He, W., Prosseda, P. P., Li, L., Kowal, T. J., Alvarado, J. A., Wang, Q., Hu, Y., Sun, Y. 2021: e52173


    Lysosomal positioning and mTOR (mammalian target of rapamycin) signaling coordinate cellular responses to nutrient levels. Inadequate nutrient sensing can result in growth delays, a hallmark of Lowe syndrome. OCRL mutations cause Lowe syndrome, but the role of OCRL in nutrient sensing is unknown. Here, we show that OCRL is localized to the centrosome by its ASH domain and that it recruits microtubule-anchoring factor SSX2IP to the centrosome, which is important in the formation of the microtubule-organizing center. Deficiency of OCRL in human and mouse cells results in loss of microtubule-organizing centers and impaired microtubule-based lysosome movement, which in turn leads to mTORC1 inactivation and abnormal nutrient sensing. Centrosome-targeted PACT-SSX2IP can restore microtubule anchoring and mTOR activity. Importantly, boosting the activity of mTORC1 restores the nutrient sensing ability of Lowe patients' cells. Our findings highlight mTORC1 as a novel therapeutic target for Lowe syndrome.

    View details for DOI 10.15252/embr.202052173

    View details for PubMedID 33987909

  • Optogenetic Modulation of Intraocular Pressure in a Glucocorticoid-Induced Ocular Hypertension Mouse Model. Translational vision science & technology Kowal, T. J., Prosseda, P. P., Ning, K., Wang, B., Alvarado, J., Sendayen, B. E., Jabbehdari, S., Stamer, W. D., Hu, Y., Sun, Y. 2021; 10 (6): 10


    Steroid-induced glaucoma is a common form of secondary open angle glaucoma characterized by ocular hypertension (elevated intraocular pressure [IOP]) in response to prolonged glucocorticoid exposure. Elevated IOP occurs with increased outflow resistance and altered trabecular meshwork (TM) function. Recently, we used an optogenetic approach in TM to regulate the 5-phosphatase, OCRL, which contributes to regulating PI(4,5)P2 levels. Here, we applied this system with the aim of reversing compromised outflow function in a steroid-induced ocular hypertension mouse model.Elevated IOP was induced by chronic subconjunctival dexamethasone injections in wild-type C57Bl/6j mice. AAV2 viruses containing optogenetic modules of cryptochrome 2 (Cry2)-OCRL-5ptase and CIBN-GFP were injected into the anterior chamber. Four weeks after viral expression and dexamethasone exposure, IOP was measured by tonometer and outflow facility was measured by perfusion apparatus. Human TM cells were treated with dexamethasone, stimulated by light and treated with rhodamine-phalloidin to analyze actin structure.Dexamethasone treatment elevated IOP and decreased outflow facility in wild-type mice. Optogenetic constructs were expressed in the TM of mouse eyes. Light stimulation caused CRY2-OCRL-5ptase to translocate to plasma membrane (CIBN-CAAX-GFP) and cilia (CIBN-SSTR3-GFP) in TM cells, which rescued the IOP and outflow facility. In addition, aberrant actin structures formed by dexamethasone treatment were reduced by optogenetic stimulation in human TM cells in culture.Subcellular targeting of inositol phosphatases to remove PIP2 represents a promising strategy to reverse defective TM function in steroid-induced ocular hypertension.Targeted modulation of OCRL may be used to decrease steroid-induced elevated IOP.

    View details for DOI 10.1167/tvst.10.6.10

    View details for PubMedID 34111256

    View details for PubMedCentralID PMC8107493

  • Optogenetic Modulation of Intraocular Pressure in a Glucocorticoid-Induced Ocular Hypertension Mouse Model TRANSLATIONAL VISION SCIENCE & TECHNOLOGY Kowal, T. J., Prosseda, P. P., Ning, K., Wang, B., Alvarado, J., Sendayen, B. E., Jabbehdari, S., Stamer, W., Hu, Y., Sun, Y. 2021; 10 (6)
  • Chronic mild and acute severe glaucomatous neurodegeneration derived from silicone oil-induced ocular hypertension. Scientific reports Fang, F., Zhang, J., Zhuang, P., Liu, P., Li, L., Huang, H., Webber, H. C., Xu, Y., Liu, L., Dalal, R., Sun, Y., Hu, Y. 2021; 11 (1): 9052


    Recently, we established silicone oil-induced ocular hypertension (SOHU) mouse model with significant glaucomatous neurodegeneration. Here we characterize two additional variations of this model that simulate two distinct glaucoma types. The first is a chronic model produced by high frequency (HF) pupillary dilation after SO-induced pupillary block, which shows sustained moderate IOP elevation and corresponding slow, mild glaucomatous neurodegeneration. We also demonstrate that although SO removal quickly returns IOP to normal, the glaucomatous neurodegeneration continues to advance to a similar degree as in the HF group without SO removal. The second, an acute model created by no pupillary dilation (ND), shows a greatly elevated IOP and severe inner retina degeneration at an early time point. Therefore, by a straightforward dilation scheme, we extend our original SOHU model to recapitulate phenotypes of two major glaucoma forms, which will be invaluable for selecting neuroprotectants and elucidating their molecular mechanisms.

    View details for DOI 10.1038/s41598-021-88690-x

    View details for PubMedID 33907301

  • Ab Interno vs. Ab Externo Microcatheter-Assisted Circumferential Trabeculotomy in Treating Patients With Primary Open-Angle Glaucoma. Frontiers in medicine Zhang, W., Wang, Y., Xin, C., Sun, Y., Cao, K., Wang, H., Wang, N. 1800; 8: 795172


    Background: Circumferential trabeculotomy have evolved from ab externo to ab interno approach. Both procedures may lower IOP, but it is unclear which maybe a superior approach. Purpose: To compare the outcomes of ab interno and ab externo circumferential trabeculotomy in patients with primary open-angle glaucoma. Design: Retrospective, comparative case series. Participants: Primary open angle glaucoma patients undergoing ab interno (40 patients in Group 1) or ab externo (54 patients in Group 2) circumferential trabeculotomy, with about one half of them having prior incisional glaucoma surgery. Methods: Outcomes including intraocular pressure (IOP), glaucoma medications and surgical complications were analyzed. Main Outcome Measures: IOP, medications and surgical success defined as an IOP of ≤ 21 mmHg and a reduction of IOP ≥20% from baseline (criterion A) or IOP ≤ 18 mmHg and a reduction of IOP 20% from baseline (criterion B) with (qualified success) or without (complete success) medications. Results: At 1 year, IOP decreased by 37.1% (26.0-14.8 mmHg) in Group 1 and 39.5% (28.5-15.1 mmHg) in Group 2. Medications decreased from 3.5 in Group 1 and 3.6 in Group 2 pre-operatively to 0.6 ± 1.0 and 0.3 ± 0.6 post-operatively, respectively. Success rates did not differ significantly between groups based on criterion A (complete and qualified success: 68.7 and 81.9% in Group 1, and 75.3 and 90.4% in Group 2, respectively) or criterion B (complete and qualified success: 58.2 and 79.3%in Group 1, and 69.5 and 88.4% in Group 2, respectively). For eyes with prior filtration surgeries, the mean percent reduction of IOP (41.7 ± 32.7% in Group 1, 39.7 ± 27.8% in Group 2, P = 0.724) and the mean medication reduction (2.9 ± 1.6 in Group 1, 3.4 ± 1.0 in Group 2, P = 0.454) were not significantly different. Conclusions: Ab interno circumferential trabeculotomy achieved comparable outcomes to ab externo trabeculotomy and may be an effective surgical option for patients with primary open-angle glaucoma.

    View details for DOI 10.3389/fmed.2021.795172

    View details for PubMedID 34988099

  • Gender of Award Recipients in Major Ophthalmology Societies. American journal of ophthalmology Nguyen, A. X., Ratan, S., Biyani, A., Trinh, X. V., Saleh, S., Sun, Y., Wu, A. Y. 2021


    To assess the gender distribution of major ophthalmology society awards.Retrospective, observational study.The study population included award recipients from nine ophthalmological societies: American Academy of Ophthalmology (AAO), American Association for Pediatric Ophthalmology and Strabismus (AAPOS), American Glaucoma Society (AGS), American Society of Cataract and Refractive Surgery (ASCRS), American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS), American Society of Retina Specialists (ASRS), American Uveitis Society (AUS), Cornea Society, and North American Neuro-Ophthalmology Society (NANOS). A gender-specific pronoun and photograph of each award recipient were extracted from professional websites to assign their gender. Main outcome measures were gender distribution by award society, year (1970-2020), type (lectureship or not), category (achievement, education, research contribution, research item, international member achievement, public service - global health, service to society), and training level.Out of 2,150 recipients for 78 awards, 1,606 (74.7%) were men and 544 (25.3%) were women. The proportion of women recipients increased from 0% in 1970 to 33.2% in 2020 (P<0.001). Women representation varied within each society (P<0.01), with ASCRS having the highest percentage (40.8%). Women received 11.0% of awards accompanied by a lecture. Women received significantly greater research-related awards than achievement or service awards. Awards for trainees and early-career ophthalmologists had a greater proportion of women (39.8%) than the rest of the awards (21.5%) (P<0.001).Overall women received awards (25.3%) at a higher prevalence than the average 1970-2020 American gender distributions of ophthalmologists. However, women are still underrepresented in many award categories and subspecialties.

    View details for DOI 10.1016/j.ajo.2021.05.021

    View details for PubMedID 34102152

  • Neuronal NMNAT2 Overexpression Does Not Achieve Significant Neuroprotection in Experimental Autoimmune Encephalomyelitis/Optic Neuritis. Frontiers in cellular neuroscience Liu, P., Huang, H., Fang, F., Liu, L., Li, L., Feng, X., Chen, W., Dalal, R., Sun, Y., Hu, Y. 2021; 15: 754651


    Optic neuritis, inflammation, and demyelination of the optic nerve (ON), is one of the most common clinical manifestations of multiple sclerosis; affected patients suffer persistent visual symptoms due to ON degeneration and secondary retinal ganglion cell (RGC) death. The mouse experimental autoimmune encephalomyelitis (EAE) model replicates optic neuritis and significant RGC soma and axon loss. Nicotinamide mononucleotide adenylyltransferases (NMNATs) are NAD+-synthetic enzymes that have been shown to be essential for axon integrity, activation of which significantly delays axonal Wallerian degeneration. NMNAT2, which is enriched in axons, has been proposed as a promising therapeutic target for axon injury-induced neurodegeneration. We therefore investigated whether activation of NMNAT2 can be used as a gene therapy strategy for neuroprotection in EAE/optic neuritis. To avoid the confounding effects in inflammatory cells, which play important roles in EAE initiation and progression, we used an RGC-specific promoter to drive the expression of the long half-life NMNAT2 mutant in mouse RGCs in vivo. However, optical coherence tomography in vivo retina imaging did not reveal significant protection of the ganglion cell complex, and visual function assays, pattern electroretinography, and optokinetic response also showed no improvement in mice with NMNAT2 overexpression. Postmortem histological analysis of retina wholemounts and semithin sections of ON confirmed the in vivo results: NMNAT2 activation in RGCs does not provide significant neuroprotection of RGCs in EAE/optic neuritis. Our studies suggest that a different degenerative mechanism than Wallerian degeneration is involved in autoimmune inflammatory axonopathy and that NMNAT2 may not be a major contributor to this mechanism.

    View details for DOI 10.3389/fncel.2021.754651

    View details for PubMedID 34707482

  • An Open-Label Phase Ib Study to Evaluate Retinal Imaging After Short-term Use of the Balance Goggles System (BGS) in Patients with Glaucoma Li, Z., Knasel, C., Nunez, M., Beykin, G., Goldstein, A., Fisher, A. C., Singh, K., Sun, Y., Chang, R. T., Lee, W., Goldberg, J. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2020
  • Comparison of Virtual Reality (PalmScan VF2000) Visual Fields Analyzer with Humphrey Visual Field in Glaucoma Patients Tran, E., Wan, L., Yan, W., Sun, Y., Chang, R. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2020
  • Optogenetic stimulation of phosphoinositides reveals a critical role of primary cilia in eye pressure regulation. Science advances Prosseda, P. P., Alvarado, J. A., Wang, B., Kowal, T. J., Ning, K., Stamer, W. D., Hu, Y., Sun, Y. 2020; 6 (18): eaay8699


    Glaucoma is a group of progressive optic neuropathies that cause irreversible vision loss. Although elevated intraocular pressure (IOP) is associated with the development and progression of glaucoma, the mechanisms for its regulation are not well understood. Here, we have designed CIBN/CRY2-based optogenetic constructs to study phosphoinositide regulation within distinct subcellular compartments. We show that stimulation of CRY2-OCRL, an inositol 5-phosphatase, increases aqueous humor outflow and lowers IOP in vivo, which is caused by a calcium-dependent actin rearrangement of the trabecular meshwork cells. Phosphoinositide stimulation also rescues defective aqueous outflow and IOP in a Lowe syndrome mouse model but not in IFT88fl/fl mice that lack functional cilia. Thus, our study is the first to use optogenetics to regulate eye pressure and demonstrate that tight regulation of phosphoinositides is critical for aqueous humor homeostasis in both normal and diseased eyes.

    View details for DOI 10.1126/sciadv.aay8699

    View details for PubMedID 32494665

    View details for PubMedCentralID PMC7190330

  • Optogenetic stimulation of phosphoinositides reveals a critical role of primary cilia in eye pressure regulation SCIENCE ADVANCES Prosseda, P. P., Alvarado, J. A., Wang, B., Kowal, T. J., Ning, K., Stamer, W., Hu, Y., Sun, Y. 2020; 6 (18)
  • Defective INPP5E distribution in NPHP1-related Senior-Loken syndrome. Molecular genetics & genomic medicine Ning, K. n., Song, E. n., Sendayen, B. E., Prosseda, P. P., Chang, K. C., Ghaffarieh, A. n., Alvarado, J. A., Wang, B. n., Haider, K. M., Berbari, N. F., Hu, Y. n., Sun, Y. n. 2020: e1566


    Senior-Loken syndrome is a rare genetic disorder that presents with nephronophthisis and retinal degeneration, leading to end-stage renal disease and progressive blindness. The most frequent cause of juvenile nephronophthisis is a mutation in the nephronophthisis type 1 (NPHP1) gene. NPHP1 encodes the protein nephrocystin-1, which functions at the transition zone (TZ) of primary cilia.We report a 9-year-old Senior-Loken syndrome boy with NPHP1 deletion, who presents with bilateral vision decrease and cystic renal disease. Renal function deteriorated to require bilateral nephrectomy and renal transplant. We performed immunohistochemistry, H&E staining, and electron microscopy on the renal sample to determine the subcellular distribution of ciliary proteins in the absence of NPHP1.Immunohistochemistry and electron microscopy of the resected kidney showed disorganized cystic structures with loss of cilia in renal tubules. Phosphoinositides have been recently recognized as critical components of the ciliary membrane and immunostaining of kidney sections for phosphoinositide 5-phosphatase, INPP5E, showed loss of staining compared to healthy control. Ophthalmic examination showed decreased electroretinogram consistent with early retinal degeneration.The decreased expression of INPP5E specifically in the primary cilium, coupled with disorganized cilia morphology, suggests a novel role of NPHP1 that it is involved in regulating ciliary phosphoinositide composition in the ciliary membrane of renal tubular cells.

    View details for DOI 10.1002/mgg3.1566

    View details for PubMedID 33306870

  • Mouse gamma-Synuclein Promoter-Mediated Gene Expression and Editing in Mammalian Retinal Ganglion Cells. The Journal of neuroscience : the official journal of the Society for Neuroscience Wang, Q. n., Zhuang, P. S., Huang, H. n., Li, L. n., Liu, L. n., Webber, H. C., Dalal, R. n., Siew, L. n., Fligor, C. M., Chang, K. C., Nahmou, M. n., Kreymerman, A. n., Sun, Y. n., Meyer, J. S., Goldberg, J. L., Hu, Y. n. 2020


    Optic neuropathies are a group of optic nerve (ON) diseases caused by various insults including glaucoma, inflammation, ischemia, trauma and genetic deficits, which are characterized by retinal ganglion cell (RGC) death and ON degeneration. An increasing number of genes involved in RGC intrinsic signaling have been found to be promising neural repair targets that can potentially be modulated directly by gene therapy, if we can achieve RGC specific gene targeting. To address this challenge, we first used adeno associated virus (AAV)-mediated gene transfer to perform a low throughput in vivo screening in both male and female mouse eyes and identified the mouse γ-synuclein (mSncg) promoter, which specifically and potently sustained transgene expression in mouse RGCs and also works in human RGCs. We further demonstrated that gene therapy that combines AAV-mSncg promoter with CRISPR/Cas9 gene editing can knockdown pro-degenerative genes in RGCs and provide effective neuroprotection in optic neuropathies.Significance Statement:Here we present an RGC-specific promoter, mouse γ-synuclein (mSncg) promoter, and perform extensive characterization and proof-of-concept studies of mSncg promoter-mediated gene expression and CRISPR/Cas9 gene editing in RGCs in vivo To our knowledge, this is the first report demonstrating in vivo neuroprotection of injured RGCs and optic nerve by AAV-mediated CRISPR/Cas9 inhibition of genes that are critical for neurodegeneration. It represents a powerful tool to achieve RGC-specific gene modulation, and also opens up a promising gene therapy strategy for optic neuropathies, the most common form of eye diseases that cause irreversible blindness.

    View details for DOI 10.1523/JNEUROSCI.0102-20.2020

    View details for PubMedID 32300046

  • Oculocerebrorenal syndrome of Lowe: Survey of ophthalmic presentations and management. European journal of ophthalmology Ma, X. n., Ning, K. n., Jabbehdari, S. n., Prosseda, P. P., Hu, Y. n., Shue, A. n., Lambert, S. R., Sun, Y. n. 2020: 1120672120920544

    View details for DOI 10.1177/1120672120920544

    View details for PubMedID 32340490

  • Longitudinal Morphological and Functional Assessment of RGC Neurodegeneration After Optic Nerve Crush in Mouse. Frontiers in cellular neuroscience Li, L. n., Huang, H. n., Fang, F. n., Liu, L. n., Sun, Y. n., Hu, Y. n. 2020; 14: 109


    The mouse optic nerve crush (ONC) model has been widely used to study optic neuropathies and central nervous system (CNS) axon injury and repair. Previous histological studies of retinal ganglion cell (RGC) somata in retina and axons in ON demonstrate significant neurodegeneration after ONC, but longitudinal morphological and functional assessment of RGCs in living animals is lacking. It is essential to establish these assays to provide more clinically relevant information for early detection and monitoring the progression of CNS neurodegeneration. Here, we present in vivo data gathered by scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), and pattern electroretinogram (PERG) at different time points after ONC in mouse eyes and corresponding histological quantification of the RGC somata and axons. Not surprisingly, direct visualization of RGCs by SLO fundus imaging correlated best with histological quantification of RGC somata and axons. Unexpectedly, OCT did not detect obvious retinal thinning until late time points (14 and 28-days post ONC) and instead detected significant retinal swelling at early time points (1-5 days post-ONC), indicating a characteristic initial retinal response to ON injury. PERG also demonstrated an early RGC functional deficit in response to ONC, before significant RGC death, suggesting that it is highly sensitive to ONC. However, the limited progression of PERG deficits diminished its usefulness as a reliable indicator of RGC degeneration.

    View details for DOI 10.3389/fncel.2020.00109

    View details for PubMedID 32410964

    View details for PubMedCentralID PMC7200994

  • Developmental Distribution of Primary Cilia in the Retinofugal Visual Pathway. The Journal of comparative neurology Alvarado, J. A., Dhande, O. S., Prosseda, P. P., Kowal, T. J., Ning, K. n., Jabbehdari, S. n., Hu, Y. n., Sun, Y. n. 2020


    The mammalian visual system is composed of circuitry connecting sensory input from the retina to the processing core of the visual cortex. The two main retinorecipient brain targets, the superior colliculus (SC) and dorsal lateral geniculate nucleus (dLGN), bridge retinal input and visual output. The primary cilium is a conserved organelle increasingly viewed as a critical sensor for the regulation of developmental and homeostatic pathways in most mammalian cell types. Moreover, cilia have been described as crucial for neurogenesis, neuronal maturation, and survival in the cortex and retina. However, cilia in the visual relay center remain to be fully described. In this study, we characterized the ciliation profile of the SC and dLGN and found that the overall number of ciliated cells declined during development. Interestingly, shorter ciliated cells in both regions were identified as neurons, whose numbers remained stable over time, suggesting that cilia retention is a critical feature for optimal neuronal function in SC and dLGN. Our study suggests that primary cilia are important for neuronal maturation and function in cells of the SC and dLGN.

    View details for DOI 10.1002/cne.25029

    View details for PubMedID 32939774

  • A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice. Journal of visualized experiments : JoVE Zhang, J., Fang, F., Li, L., Huang, H., Webber, H. C., Sun, Y., Mahajan, V. B., Hu, Y. 2019


    Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing stable IOP elevation in mice that mimics the post-operative complication of using silicone oil (SO) as a tamponade agent in human vitreoretinal surgery. In this protocol, SO is injected into the anterior chamber of the mouse eye to block the pupil and prevent inflow of aqueous humor. The posterior chamber accumulates aqueous humor and this in turn increases the IOP of the posterior segment. A single SO injection produces reliable, sufficient, and stable IOP elevation, which induces significant glaucomatous neurodegeneration. This model is a true replicate of secondary glaucoma in the eye clinic. To further mimic the clinical setting, SO can be removed from the anterior chamber to reopen the drainage pathway and allow inflow of aqueous humor, which is drained through the trabecular meshwork (TM) at the angle of the anterior chamber. Because IOP quickly returns to normal, the model can be used to test the effect of lowering IOP on glaucomatous retinal ganglion cells. This method is straightforward, does not require special equipment or repeat procedures, closely simulates clinical situations, and may be applicable to diverse animal species. However, minor modifications may be required.

    View details for DOI 10.3791/60409

    View details for PubMedID 31789319

  • A novel inducible and reversible mouse glaucoma model: Silicone Oil-Induced Ocular Hypertension Under-detected (SOHU) Zhang, J., Li, L., Huang, H., Webber, H., Li, S., Tang, P., Mahajan, V. B., Sun, Y., Zhang, M., Hu, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • Neuroprotection of Retinal Ganglion Cells by AAV2-gamma-Synuclein Promoter-Mediated CRISPR/Cas9 Gene Editing Li, L., Wang, Q., Huang, H., Sun, Y., Goldberg, J. L., Hu, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • The Role of Phosphoinositides in Aqueous Humor Dynamics via Optogenetic Stimulation in the Trabecular Meshwork Alvarado, J., Prosseda, P., Ning, K., Kowal, T., Wang, B., Hu, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • Role of inositol phosphatase OCRL in microtubule nucleation: Implications for Oculocerebrorenal Syndrome of Lowe Kowal, T., Wang, B., Prosseda, P., Alvarado, J., He, W., Ning, K., Hu, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • Characterization of primary cilia in mouse retina during retinal development Ning, K., Kowal, T., Chang, K., Alvarado, J., Silva, R., Kreymerman, A., Mahajan, V. B., Hu, Y., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • Oculocerebrorenal Syndrome of Lowe: Characterizations of Ocular Presentation and Management Ma, X., Ning, K., Kowal, T., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • Ocular and systemic presentations of phosphoinositide signaling defects Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2019
  • Silicone oil-induced ocular hypertension and glaucomatous neurodegeneration in mouse ELIFE Zhang, J., Li, L., Huang, H., Fang, F., Webber, H. C., Zhuang, P., Liu, L., Dalal, R., Tang, P. H., Mahajan, V. B., Sun, Y., Li, S., Zhang, M., Goldberg, J. L., Hu, Y. 2019; 8
  • Silicone oil-induced ocular hypertension and glaucomatous neurodegeneration in mouse. eLife Zhang, J., Li, L., Huang, H., Fang, F., Webber, H. C., Zhuang, P., Liu, L., Dalal, R., Tang, P. H., Mahajan, V. B., Sun, Y., Li, S., Zhang, M., Goldberg, J. L., Hu, Y. 2019; 8


    Understanding the molecular mechanism of glaucoma and development of neuroprotectants are significantly hindered by the lack of a reliable animal model that accurately recapitulates human glaucoma. Here we sought to develop a mouse model for the secondary glaucoma that is often observed in humans after silicone oil (SO) blocks the pupil or migrates into the anterior chamber following vitreoretinal surgery. We observed significant intraocular pressure (IOP) elevation after intracameral injection of SO, and that SO removal allows IOP to return quickly to normal. This simple, inducible and reversible mouse ocular hypertension model shows dynamic changes of visual function that correlate with progressive RGC loss and axon degeneration. It may be applicable with only minor modifications to a range of animal species in which it will generate stable, robust IOP elevation and significant neurodegeneration that will facilitate selection of neuroprotectants and investigating the pathogenesis of ocular hypertension-induced glaucoma.

    View details for PubMedID 31090540

  • AKT-dependent and -independent pathways mediate PTEN deletion-induced CNS axon regeneration. Cell death & disease Huang, H., Miao, L., Yang, L., Liang, F., Wang, Q., Zhuang, P., Sun, Y., Hu, Y. 2019; 10 (3): 203


    Phosphatase and tensin homolog (PTEN) acts as a brake for the phosphatidylinositol 3-kinase-AKT-mTOR complex 1 (mTORC1) pathway, the deletion of which promotes potent central nervous system (CNS) axon regeneration. Previously, we demonstrated that AKT activation is sufficient to promote CNS axon regeneration to a lesser extent than PTEN deletion. It is still questionable whether AKT is entirely responsible for the regenerative effect of PTEN deletion on CNS axons. Here, we show that blocking AKT or its downstream effectors, mTORC1 and GSK3beta, significantly reduces PTEN deletion-induced mouse optic nerve regeneration, indicating the necessary role of AKT-dependent signaling. However, AKT is only marginally activated in PTEN-null mice due to mTORC1-mediated feedback inhibition. That combining PTEN deletion with AKT overexpression or GSK3beta deletion achieves significantly more potent axonal regeneration suggests an AKT-independent pathway for axon regeneration. Elucidating the AKT-independent pathway is required to develop effective strategies for CNS axon regeneration.

    View details for PubMedID 30814515

  • AKT-dependent and -independent pathways mediate PTEN deletion-induced CNS axon regeneration CELL DEATH & DISEASE Huang, H., Miao, L., Yang, L., Liang, F., Wang, Q., Zhuang, P., Sun, Y., Hu, Y. 2019; 10
  • Review of Ocular Manifestations of Joubert Syndrome. Genes Wang, S. F., Kowal, T. J., Ning, K., Koo, E. B., Wu, A. Y., Mahajan, V. B., Sun, Y. 2018; 9 (12)


    Joubert syndrome is a group of rare disorders that stem from defects in a sensory organelle, the primary cilia. Affected patients often present with disorders involving multiple organ systems, including the brain, eyes, and kidneys. Common symptoms include breathing abnormalities, mental developmental delays, loss of voluntary muscle coordination, and abnormal eye movements, with a diagnostic "molar tooth" sign observed by magnetic resonance imaging (MRI) of the midbrain. We reviewed the ocular phenotypes that can be found in patients with Joubert syndrome. Ocular motor apraxia is the most frequent (80% of patients), followed by strabismus (74%) and nystagmus (72%). A minority of patients also present with ptosis (43%), chorioretinal coloboma (30%), and optic nerve atrophy (22%). Although mutations in 34 genes have been found to be associated with Joubert syndrome, retinal degeneration has been reported in only 38% of patients. Mutations in AHI1 and CEP290, genes critical to primary cilia function, have been linked to retinal degeneration. In conclusion, Joubert syndrome is a rare pleiotropic group of disorders with variable ocular presentations.

    View details for PubMedID 30518138

  • Considerations for ophthalmic applications of optogenetics ACTA OPHTHALMOLOGICA Wood, E. H., Kreymerman, A., Sun, Y., Drenser, K. A., Trese, M. T. 2018; 96 (8): E1037

    View details for PubMedID 29855158

  • Review of Ocular Manifestations of Joubert Syndrome GENES Wang, S. F., Kowal, T. J., Ning, K., Koo, E. B., Wu, A. Y., Mahajan, V. B., Sun, Y. 2018; 9 (12)
  • Coordination of Necessary and Permissive Signals by PTEN Inhibition for CNS Axon Regeneration FRONTIERS IN NEUROSCIENCE Zhang, J., Yang, D., Huang, H., Sun, Y., Hu, Y. 2018; 12
  • Coordination of Necessary and Permissive Signals by PTEN Inhibition for CNS Axon Regeneration. Frontiers in neuroscience Zhang, J., Yang, D., Huang, H., Sun, Y., Hu, Y. 2018; 12: 558


    In the nearly 10 years since PTEN was identified as a prominent intrinsic inhibitor of CNS axon regeneration, the PTEN negatively regulated PI3K-AKT-mTOR pathway has been intensively explored in diverse models of axon injury and diseases and its mechanism for axon regeneration is becoming clearer. It is therefore timely to summarize current knowledge and discuss future directions of translational regenerative research for neural injury and neurodegenerative diseases. Using mouse optic nerve crush as an in vivo retinal ganglion cell axon injury model, we have conducted an extensive molecular dissection of the PI3K-AKT pathway to illuminate the cross-regulating mechanisms in axon regeneration. AKT is the nodal point that coordinates both positive and negative signals to regulate adult CNS axon regeneration through two parallel pathways, activating mTORC1 and inhibiting GSK3ββ. Activation of mTORC1 or its effector S6K1 alone can only slightly promote axon regeneration, whereas blocking mTORC1 significantly prevent axon regeneration, suggesting the necessary role of mTORC1 in axon regeneration. However, mTORC1/S6K1-mediated feedback inhibition prevents potent AKT activation, which suggests a key permissive signal from an unidentified AKT-independent pathway is required for stimulating the neuron-intrinsic growth machinery. Future studies into this complex neuron-intrinsic balancing mechanism involving necessary and permissive signals for axon regeneration is likely to lead eventually to safe and effective regenerative strategies for CNS repair.

    View details for DOI 10.3389/fnins.2018.00558

    View details for PubMedID 30158848

    View details for PubMedCentralID PMC6104488

  • The role of inositol phosphatase OCRL in microtubule nucleation: Implications for Oculocerebrorenal Syndrome of Lowe Wang, B., Prosseda, P. P., He, W., Kowal, T., Alvarado, J. A., Ning, K., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
  • Ocular and renal phenotypes of NPHP1 deletion in Senior Loken syndrome Ning, K., Song, E., Haider, K. M., Ghaffarieh, A., Alvarado, J. A., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
  • Optogenetic Regulation of Aqueous Outflow in Mouse Trabecular Meshwork Alvarado, J. A., Prosseda, P. P., Luo, N., Wang, B., Ning, K., He, W., Kowal, T., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
  • Single particle tracking of nicotinic acetylcholine receptors (AChRs): implication for the pathogenesis of ocular myasthenia gravis (MG) He, W., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
  • Intraluminal Deposits Found in Glaucoma Tube Shunts Via Anterior Segment Ocular Coherence Tomography JOURNAL OF GLAUCOMA Alvarado, J. A., Srivastava, V., Sun, Y. 2018; 27 (3): E68–E71


    To describe and characterize a novel observation of intraluminal deposits of glaucoma tube shunts (TS) using spectral domain (SD) ocular coherence topography (OCT).Fifteen TS in 11 patients diagnosed with primary open-angle, neovascular, aphakic, and uveitic glaucomas. Both Ahmed (n=11) and Baerveldt (n=4) TS were examined with 5-line raster anterior segment SD-OCT imaging.The exposed tubes of 2 patients had highly reflective intraluminal deposits in the corresponding exposed areas. Seven tubes without exposure had a thin rim of highly reflective material. Six tubes were clear of luminal deposits. The most common diagnosis in the study was uveitic glaucoma which occurred in 5 of the 15 eyes (33%). The next most common diagnosis was primary open-angle glaucoma which occurred in 4 of the 15 eyes (25%). There were 2 nonvalved Baerveldt tubes in each group. The mean duration of TS implantation was 15.0 months in the deposit group and 33.7 months in the group without luminal deposits. The majority of patients in each group were using eye drops at presentation (88.9% deposit, 83.3% clear), and the average intraocular pressure was 20.2 mm Hg in the deposit group and 19.0 mm Hg in the clear group.Anterior segment OCT imaging may be used to evaluate TS integrity. Intraluminal deposits in TS may occur as a natural response to implanted drainage device, possibly as an inflammatory response.

    View details for PubMedID 29240598

    View details for PubMedCentralID PMC5831525

  • Proteomic analysis of the human retina reveals region-specific susceptibilities to metabolic-and oxidative stress-related diseases PLOS ONE Velez, G., Machlab, D. A., Tang, P. H., Sun, Y., Tsang, S. H., Bassuk, A. G., Mahajan, V. B. 2018; 13 (2): e0193250


    Differences in regional protein expression within the human retina may explain molecular predisposition of specific regions to ophthalmic diseases like age-related macular degeneration, cystoid macular edema, retinitis pigmentosa, and diabetic retinopathy. To quantify protein levels in the human retina and identify patterns of differentially-expressed proteins, we collected foveomacular, juxta-macular, and peripheral retina punch biopsies from healthy donor eyes and analyzed protein content by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Protein expression was analyzed with 1-way ANOVA, gene ontology, pathway representation, and network analysis. We identified a mean of 1,974 proteins in the foveomacular retina, 1,999 in the juxta-macular retina, and 1,779 in the peripheral retina. Six hundred ninety-seven differentially-expressed proteins included those unique to and abundant in each anatomic region. Proteins with higher expression in each region include: heat-shock protein 90-alpha (HSP90AA1), and pyruvate kinase (PKM) in the foveomacular retina; vimentin (VIM) and fructose-bisphosphate aldolase C (ALDOC); and guanine nucleotide-binding protein subunit beta-1 (GNB1) and guanine nucleotide-binding protein subunit alpha-1 (GNAT1) in the peripheral retina. Pathway analysis identified downstream mediators of the integrin signaling pathway to be highly represented in the foveomacular region (P = 6.48 e-06). Metabolic pathways were differentially expressed among all retinal regions. Gene ontology analysis showed that proteins related to antioxidant activity were higher in the juxta-macular and the peripheral retina, but present in lower amounts in the foveomacular retina. Our proteomic analysis suggests that certain retinal regions are susceptible to different forms of metabolic and oxidative stress. The findings give mechanistic insight into retina function, reveal important molecular processes, and prioritize new pathways for therapeutic targeting.

    View details for PubMedID 29466423

  • Neuroprotection by eIF2 alpha-CHOP inhibition and XBP-1 activation in EAE/optic neuritiss CELL DEATH & DISEASE Huang, H., Miao, L., Liang, F., Liu, X., Xu, L., Teng, X., Wang, Q., Ridder, W. H., Shindler, K. S., Sun, Y., Hu, Y. 2017; 8: e2936


    No therapies exist to prevent neuronal deficits in multiple sclerosis (MS), because the molecular mechanism responsible for the progressive neurodegeneration is unknown. We previously showed that axon injury-induced neuronal endoplasmic reticulum (ER) stress plays an important role in retinal ganglion cell (RGC) death and optic nerve degeneration in traumatic and glaucomatous optic neuropathies. Optic neuritis, one of the most common clinical manifestations of MS, is readily modeled by experimental autoimmune encephalomyelitis (EAE) in mouse. Using this in vivo model, we now show that ER stress is induced early in EAE and that modulation of ER stress by inhibition of eIF2α-CHOP and activation of XBP-1 in RGC specifically, protects RGC somata and axons and preserves visual function. This finding adds to the evidence that ER stress is a general upstream mechanism for neurodegeneration and suggests that targeting ER stress molecules is a promising therapeutic strategy for neuroprotection in MS.

    View details for PubMedID 28726788

  • Occult lens subluxation related to laser peripheral iridotomy A case report and literature review MEDICINE Hu, R., Wang, X., Wang, Y., Sun, Y. 2017; 96 (10)


    Laser peripheral iridotomy (LPI) is commonly performed as a primary treatment for acute primary angle closure glaucoma after administration of anti-glaucoma medications or for prevention of this condition. Minor complications may occur following LPI and most of them do not have deleterious consequences. We report a rare case of lens subluxation that has a possible relationship with LPI treatment.A 54-year-old female patient was initially referred for surgical treatment of medication-uncontrollable angle closure glaucoma in her left eye. The patient had undergone Neodymium:YAG LPI at an outside hospital 2 months prior to the presentation due to an episode of elevated intraocular pressure (IOP). About 5 days after the LPI, she had spontaneous blurred vision, redness, and pain in the left eye. Her IOP was found to re-rise and was not controlled well even with maximum tolerated anti-glaucoma medications during the following 2 months. On slit-lamp examination, the significant shallowing of both peripheral and central anterior chamber was noted in the left eye. Ultrasound biomicroscopy examination revealed the lens tilting towards the iris and the inferior zonular dehiscence corresponding to the iridotomy site.Lens subluxation secondary to LPI treatment in the left eye.Phacoemulsification combined with in-the-bag intraocular lens implantation was performed in the left eye. The zonular weakness corresponding to the iridotomy site was further confirmed during surgery.The patient's IOP remained stable in the first postoperative 3 months without additional anti-glaucoma medications.Laser peripheral iridotomy may cause structural zonular damage, and ophthalmologists should be aware of this potential complication and proceed with caution.

    View details for DOI 10.1097/MD.0000000000006255

    View details for Web of Science ID 000396041000038

    View details for PubMedID 28272229

  • Loss of OCRL increases ciliary PI(4,5)P2 in Lowe oculocerebrorenal syndrome. Journal of cell science Prosseda, P. P., Luo, N. n., Wang, B. n., Alvarado, J. A., Hu, Y. n., Sun, Y. n. 2017; 130 (20): 3447–54


    Lowe syndrome is a rare X-linked disorder characterized by bilateral congenital cataracts and glaucoma, mental retardation, and proximal renal tubular dysfunction. Mutations in OCRL, an inositol polyphosphate 5-phosphatase that dephosphorylates PI(4,5)P2, cause Lowe syndrome. Previously we showed that OCRL localizes to the primary cilium, which has a distinct membrane phospholipid composition, but disruption of phosphoinositides in the ciliary membrane is poorly understood. Here, we demonstrate that cilia from Lowe syndrome patient fibroblasts exhibit increased levels of PI(4,5)P2 and decreased levels of PI4P. In particular, subcellular distribution of PI(4,5)P2 build-up was observed at the transition zone. Accumulation of ciliary PI(4,5)P2 was pronounced in mouse embryonic fibroblasts (MEFs) derived from Lowe syndrome mouse model as well as in Ocrl-null MEFs, which was reversed by reintroduction of OCRL. Similarly, expression of wild-type OCRL reversed the elevated PI(4,5)P2 in Lowe patient cells. Accumulation of sonic hedgehog protein in response to hedgehog agonist was decreased in MEFs derived from a Lowe syndrome mouse model. Together, our findings show for the first time an abnormality in ciliary phosphoinositides of both human and mouse cell models of Lowe syndrome.

    View details for PubMedID 28871046

  • Ocular Pathology of Oculocerebrorenal Syndrome of Lowe: Novel Mutations and Genotype-Phenotype Analysis. Scientific reports Song, E. n., Luo, N. n., Alvarado, J. A., Lim, M. n., Walnuss, C. n., Neely, D. n., Spandau, D. n., Ghaffarieh, A. n., Sun, Y. n. 2017; 7 (1): 1442


    Mutations in the OCRL1 gene result in the oculocerebrorenal syndrome of Lowe, with symptoms including congenital bilateral cataracts, glaucoma, renal failure, and neurological impairments. OCRL1 encodes an inositol polyphosphate 5-phosphatase which preferentially dephosphorylates phosphatidylinositide 4,5 bisphosphate (PI(4,5)P2). We have identified two novel mutations in two unrelated Lowe syndrome patients with congenital glaucoma. Novel deletion mutations are detected at c.739-742delAAAG in Lowe patient 1 and c.1595-1631del in Lowe patient 2. End stage glaucoma in patient 2 resulted in the enucleation of the eye, which on histology demonstrated corneal keloid, fibrous infiltration of the angle, ectropion uvea, retinal gliosis, and retinal ganglion cell loss. We measured OCRL protein levels in patient keratinocytes and found that Lowe 1 patient cells had significantly reduced OCRL protein as compared to the control keratinocytes. Genotype-phenotype correlation of OCRL1 mutations associated with congenital glaucoma revealed clustering of missense and deletion mutations in the 5-phosphatase domain and the RhoGAP-like domain. In conclusion, we report novel OCRL1 mutations in Lowe syndrome patients and the corresponding histopathologic analysis of one patient's ocular pathology.

    View details for PubMedID 28473699

    View details for PubMedCentralID PMC5431454

  • Primary cilia signaling mediates intraocular pressure sensation PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Luo, N., Conwell, M. D., Chen, X., Kettenhofen, C. I., Westlake, C. J., Cantor, L. B., Wells, C. D., Weinreb, R. N., Corson, T. W., Spandau, D. F., Joos, K. M., Iomini, C., Obukhov, A. G., Sun, Y. 2014; 111 (35): 12871-12876


    Lowe syndrome is a rare X-linked congenital disease that presents with congenital cataracts and glaucoma, as well as renal and cerebral dysfunction. OCRL, an inositol polyphosphate 5-phosphatase, is mutated in Lowe syndrome. We previously showed that OCRL is involved in vesicular trafficking to the primary cilium. Primary cilia are sensory organelles on the surface of eukaryotic cells that mediate mechanotransduction in the kidney, brain, and bone. However, their potential role in the trabecular meshwork (TM) in the eye, which regulates intraocular pressure, is unknown. Here, we show that TM cells, which are defective in glaucoma, have primary cilia that are critical for response to pressure changes. Primary cilia in TM cells shorten in response to fluid flow and elevated hydrostatic pressure, and promote increased transcription of TNF-α, TGF-β, and GLI1 genes. Furthermore, OCRL is found to be required for primary cilia to respond to pressure stimulation. The interaction of OCRL with transient receptor potential vanilloid 4 (TRPV4), a ciliary mechanosensory channel, suggests that OCRL may act through regulation of this channel. A novel disease-causing OCRL allele prevents TRPV4-mediated calcium signaling. In addition, TRPV4 agonist GSK 1016790A treatment reduced intraocular pressure in mice; TRPV4 knockout animals exhibited elevated intraocular pressure and shortened cilia. Thus, mechanotransduction by primary cilia in TM cells is implicated in how the eye senses pressure changes and highlights OCRL and TRPV4 as attractive therapeutic targets for the treatment of glaucoma. Implications of OCRL and TRPV4 in primary cilia function may also shed light on mechanosensation in other organ systems.

    View details for DOI 10.1073/pnas.1323292111

    View details for Web of Science ID 000341230800077

    View details for PubMedID 25143588

  • STAT6-Mediated Keratitis and Blepharitis: A Novel Murine Model of Ocular Atopic Dermatitis INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Turner, M. J., DaSilva-Arnold, S., Luo, N., Hu, X., West, C. C., Sun, L., Hall, C., Bradish, J., Kaplan, M. H., Travers, J. B., Sun, Y. 2014; 55 (6): 3803-3808


    Atopic dermatitis (AD) is a common inflammatory disease that can affect the eye, resulting in ocular pathologies, including blepharitis, keratitis, and uveitis; however, the pathogenic mechanisms underlying the ocular manifestations of AD are not well understood.In the present study, we characterized the ocular pathologies that develop in the Stat6VT mouse model of AD. We examined the cytokine profile of the eyelid lesions, measured the behavioral response, and documented the treatment response to topical steroids.Our results show that Stat6VT mice spontaneously developed blepharitis, keratitis, and uveitis similar to that observed in patients with AD. Histologic findings of allergic inflammation in affected eyelids in this model include the presence of a lymphocyte-predominant infiltrate and tissue eosinophilia in the dermis. Gene expression analysis of affected eyelid tissue by quantitative PCR revealed increased amounts of mRNAs for the Th2 cytokines IL-4, IL-5, and IL-13. In addition, increased eyelid scratching was seen in Stat6VT mice with blepharitis. Topical treatment with the corticosteroid clobetasol reduced eyelid inflammation, tissue eosinophilia, and Th2 cytokine expression.The development of AD-like ocular pathologies in this model supports the idea that in humans, AD-associated disease of the eye may be driven by Th2-mediated inflammation and demonstrates that the Stat6VT mouse may be a useful system in which to further investigate pathogenesis of and treatment strategies for blepharitis and other ocular diseases that develop in association with AD.

    View details for DOI 10.1167/iovs.13-13685

    View details for Web of Science ID 000339485800053

    View details for PubMedID 24845637

  • Serum deprivation inhibits the transcriptional co-activator YAP and cell growth via phosphorylation of the 130-kDa isoform of Angiomotin by the LATS1/2 protein kinases PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Adler, J. J., Johnson, D. E., Heller, B. L., Bringman, L. R., Ranahan, W. P., Conwell, M. D., Sun, Y., Hudmon, A., Wells, C. D. 2013; 110 (43): 17368-17373


    Large tumor suppressor (LATS)1/2 protein kinases transmit Hippo signaling in response to intercellular contacts and serum levels to limit cell growth via the inhibition of Yes-associated protein (YAP). Here low serum and high LATS1 activity are found to enhance the levels of the 130-kDa isoform of angiomotin (Amot130) through phosphorylation by LATS1/2 at serine 175, which then forms a binding site for 14-3-3. Such phosphorylation, in turn, enables the ubiquitin ligase atrophin-1 interacting protein (AIP)4 to bind, ubiquitinate, and stabilize Amot130. Consistently, the Amot130 (S175A) mutant, which lacks LATS phosphorylation, bound AIP4 poorly under all conditions and showed reduced stability. Amot130 and AIP4 also promoted the ubiquitination and degradation of YAP in response to serum starvation, unlike Amot130 (S175A). Moreover, silencing Amot130 expression blocked LATS1 from inhibiting the expression of connective tissue growth factor, a YAP-regulated gene. Concordant with phosphorylated Amot130 specifically mediating these effects, wild-type Amot130 selectively induced YAP phosphorylation and reduced transcription of connective tissue growth factor in an AIP4-dependent manner versus Amot130 (S175A). Further, Amot130 but not Amot130 (S175A) strongly inhibited the growth of MDA-MB-468 breast cancer cells. The dominant-negative effects of Amot130 (S175A) on YAP signaling also support that phosphorylated Amot130 transduces Hippo signaling. Likewise, Amot130 expression provoked premature growth arrest during mammary cell acini formation, whereas Amot130 (S175A)-expressing cells formed enlarged and poorly differentiated acini. Taken together, the phosphorylation of Amot130 by LATS is found to be a key feature that enables it to inhibit YAP-dependent signaling and cell growth.

    View details for DOI 10.1073/pnas.1308236110

    View details for Web of Science ID 000325943300050

    View details for PubMedID 24101513

  • Compensatory Role of Inositol 5-Phosphatase INPP5B to OCRL in Primary Cilia Formation in Oculocerebrorenal Syndrome of Lowe PLOS ONE Luo, N., Kumar, A., Conwell, M., Weinreb, R. N., Anderson, R., Sun, Y. 2013; 8 (6)


    Inositol phosphatases are important regulators of cell signaling, polarity, and vesicular trafficking. Mutations in OCRL, an inositol polyphosphate 5-phosphatase, result in Oculocerebrorenal syndrome of Lowe, an X-linked recessive disorder that presents with congenital cataracts, glaucoma, renal dysfunction and mental retardation. INPP5B is a paralog of OCRL and shares similar structural domains. The roles of OCRL and INPP5B in the development of cataracts and glaucoma are not understood. Using ocular tissues, this study finds low levels of INPP5B present in human trabecular meshwork but high levels in murine trabecular meshwork. In contrast, OCRL is localized in the trabecular meshwork and Schlemm's canal endothelial cells in both human and murine eyes. In cultured human retinal pigmented epithelial cells, INPP5B was observed in the primary cilia. A functional role for INPP5B is revealed by defects in cilia formation in cells with silenced expression of INPP5B. This is further supported by the defective cilia formation in zebrafish Kupffer's vesicles and in cilia-dependent melanosome transport assays in inpp5b morphants. Taken together, this study indicates that OCRL and INPP5B are differentially expressed in the human and murine eyes, and play compensatory roles in cilia development.

    View details for DOI 10.1371/journal.pone.0066727

    View details for Web of Science ID 000320846500099

    View details for PubMedID 23805271

  • Evidence of a role of inositol polyphosphate 5-phosphatase INPP5E in cilia formation in zebrafish VISION RESEARCH Luo, N., Lu, J., Sun, Y. 2012; 75: 98-107


    Inositol phosphatases are important regulators of cell signaling and membrane trafficking. Mutations in inositol polyphosphate 5-phosphatase, INPP5E, have been identified in Joubert syndrome, a rare congenital disorder characterized by midbrain malformation, retinitis pigmentosa, renal cysts, and polydactyly. Previous studies have implicated primary cilia abnormalities in Joubert syndrome, yet the role of INPP5E in cilia formation is not well understood. In this study, we examined the function of INPP5E in cilia development in zebrafish. Using specific antisense morpholino oligonucleotides to knockdown Inpp5e expression, we observed phenotypes of microphthalmia, pronephros cysts, pericardial effusion, and left-right body axis asymmetry. The Inpp5e morphant zebrafish exhibited shortened and decreased cilia formation in the Kupffer's vesicle and pronephric ducts as compared to controls. Epinephrine-stimulated melanosome trafficking was delayed in the Inpp5e zebrafish morphants. Expression of human INPP5E expression rescued the phenotypic defects in the Inpp5e morphants. Taken together, we showed that INPP5E is critical for the cilia development in zebrafish.

    View details for DOI 10.1016/j.visres.2012.09.011

    View details for Web of Science ID 000312426100015

    View details for PubMedID 23022135

  • OCRL localizes to the primary cilium: a new role for cilia in Lowe syndrome HUMAN MOLECULAR GENETICS Luo, N., West, C. C., Murga-Zamalloa, C. A., Sun, L., Anderson, R. M., Wells, C. D., Weinreb, R. N., Travers, J. B., Khanna, H., Sun, Y. 2012; 21 (15): 3333-3344


    Oculocerebral renal syndrome of Lowe (OCRL or Lowe syndrome), a severe X-linked congenital disorder characterized by congenital cataracts and glaucoma, mental retardation and kidney dysfunction, is caused by mutations in the OCRL gene. OCRL is a phosphoinositide 5-phosphatase that interacts with small GTPases and is involved in intracellular trafficking. Despite extensive studies, it is unclear how OCRL mutations result in a myriad of phenotypes found in Lowe syndrome. Our results show that OCRL localizes to the primary cilium of retinal pigment epithelial cells, fibroblasts and kidney tubular cells. Lowe syndrome-associated mutations in OCRL result in shortened cilia and this phenotype can be rescued by the introduction of wild-type OCRL; in vivo, knockdown of ocrl in zebrafish embryos results in defective cilia formation in Kupffer vesicles and cilia-dependent phenotypes. Cumulatively, our data provide evidence for a role of OCRL in cilia maintenance and suggest the involvement of ciliary dysfunction in the manifestation of Lowe syndrome.

    View details for DOI 10.1093/hmg/dds163

    View details for Web of Science ID 000306414900003

    View details for PubMedID 22543976

  • p38 phosphorylates Rb on Ser567 by a novel, cell cycle-independent mechanism that triggers Rb-Hdm2 interaction and apoptosis ONCOGENE Delston, R. B., Matatall, K. A., Sun, Y., Onken, M. D., Harbour, J. W. 2011; 30 (5): 588-599


    The retinoblastoma protein (Rb) inhibits both cell division and apoptosis, but the mechanism by which Rb alternatively regulates these divergent outcomes remains poorly understood. Cyclin-dependent kinases (Cdks) promote cell division by phosphorylating and reversibly inactivating Rb by a hierarchical series of phosphorylation events and sequential conformational changes. The stress-regulated mitogen-activated protein kinase p38 also phosphorylates Rb, but it does so in a cell cycle-independent manner that is associated with apoptosis rather than with cell division. Here, we show that p38 phosphorylates Rb by a novel mechanism that is distinct from that of Cdks. p38 bypasses the cell cycle-associated hierarchical phosphorylation and directly phosphorylates Rb on Ser567, which is not phosphorylated during the normal cell cycle. Phosphorylation by p38, but not Cdks, triggers an interaction between Rb and the human homolog of murine double minute 2 (Hdm2), leading to degradation of Rb, release of E2F1 and cell death. These findings provide a mechanistic explanation as to how Rb regulates cell division and apoptosis through different kinases, and reveal how Hdm2 may functionally link the tumor suppressors Rb and p53.

    View details for DOI 10.1038/onc.2010.442

    View details for Web of Science ID 000286922300007

    View details for PubMedID 20871633

  • Functional analysis of the p53 pathway in response to ionizing radiation in uveal melanoma INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE Sun, Y., Tran, B. N., Worley, L. A., Delston, R. B., Harbour, J. W. 2005; 46 (5): 1561-1564


    Uveal melanomas are notoriously radioresistant and thus necessitate treatment with extremely high radiation doses that often cause ocular complications. The p53 tumor suppressor pathway is a major mediator of the cellular response to radiation-induced DNA damage, suggesting that this pathway may be defective in uveal melanoma. The current study was conducted to analyze the functional integrity of the p53 pathway in primary uveal melanoma cells.The p53 gene was sequenced in three primary uveal melanoma cells lines. Cultured primary uveal melanoma cells (MM28, MM50, Mel202, Mel270, and Mel290), MCF7 breast carcinoma cells, normal uveal melanocytes (UM47), and normal human diploid fibroblasts (NHDFs) were irradiated at 250 kVp and 12 mA at a dose rate of 1.08 Gy/min for a total dose of up to 20 Gy. Cell viability was analyzed with trypan blue exclusion. Western blot analysis was used to analyze the expression of p53, p53-phospho-Ser15, p21, Bax, PUMA, and Bcl-x(L).No p53 gene mutations were found in MM28, MM50, or Mel270 cells. Upstream signaling to p53 was intact, with normal induction of p53 and phosphorylation of p53-Ser15, in all five cell lines. Radiation-induced downstream activation of p21 was defective in MM28 and MM50 cells, and activation of Bax was defective in MM50 and Mel290 cells. MM28, MM50, and Mel202 cells failed to deamidate Bcl-x(L) in response to radiation-induced DNA damage. Overall, four of the five uveal melanoma cell lines exhibited at least one downstream defect in the p53 pathway.Expression of p53 and upstream signaling to p53 in response to radiation-induced DNA damage appear to be intact in most uveal melanomas. In contrast, functional defects in the p53 pathway downstream of p53 activation appear to be common. Further elucidation of p53 pathway abnormalities in uveal melanoma may allow therapeutic interventions to increase the radiosensitivity of the tumors.

    View details for DOI 10.1167/iovs.04-1362

    View details for Web of Science ID 000228708000005

    View details for PubMedID 15851551