All Publications

  • Defective neuronal differentiation in Lowe syndrome is associated with mitochondrial dysfunction and impaired cilia-related Sonic Hedgehog signaling. eLife Walkiewicz, G., Chen, S., Lo, C., Zhao, J., Liu, Z., Wang, B., Wang, Q., Kowal, T. J., Lawson, B., Sun, Y. 2026; 13

    Abstract

    Human brain development requires tight coordination of metabolic and signaling pathways. Lowe syndrome (LS) is a recessive X-linked disorder characterized by proximal tubular renal disease, congenital cataracts, glaucoma, and neurodevelopmental delays. While LS results from mutations in the OCRL gene, which encodes an inositol polyphosphate 5-phosphatase, the cellular mechanisms driving neuronal dysfunction remain poorly understood. In this study, using patient-derived iPSC neurons, an Ocrl knockout mouse model, and an independent zebrafish OCRL-deficient model, we identified mitochondrial dysfunction as a conserved phenotype of OCRL loss across species. Collectively, our findings showed that OCRL deficiency leads to reduced mitochondrial activity, decreased mtDNA levels, reduced mitochondrial content (TOM20), and increased oxidative stress. We further showed that OCRL-deficient neural cells exhibited an altered balance of neuronal versus astrocytic differentiation, rather than a defect in neurogenesis. Additionally, we observed impaired Sonic Hedgehog (Shh) signaling and ciliary homeostasis. Thus, our findings support a model in which OCRL deficiency is associated with mitochondrial dysfunction, increased oxidative stress, altered neural lineage balance, and reduced Hedgehog pathway activity, providing a framework for understanding these interconnected phenotypes.

    View details for DOI 10.7554/eLife.104055

    View details for PubMedID 42758533

    View details for PubMedCentralID PMC13588622

  • Defective neuronal differentiation in Lowe syndrome is associated with mitochondrial dysfunction and impaired cilia-related Sonic Hedgehog signaling ELIFE Walkiewicz, G., Chen, S., Lo, C., Zhao, J., Liu, Z., Wang, B., Wang, Q., Kowal, T. J., Lawson, B., Sun, Y. 2026; 13

    View details for DOI 10.7554/eLife.104055.3.sa2

    View details for Web of Science ID 001880077000001

  • CRISPR and Gene Augmentation Rescue Trabecular Meshwork Dysfunction in iPSC Models of Lowe Syndrome. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Chen, S., Liu, Z., Wang, W., Wang, Q., Kowal, T. J., Zhang, F., Walkiewicz, G., Hossen, F., Lachman, H. M., Zhou, J., Wang, Y., Sun, Y. 2026: e77704

    Abstract

    Lowe syndrome is a rare, currently incurable multisystem disorder that affects the eyes, kidneys, and central nervous system. It is caused by mutations in the OCRL gene, which encodes an inositol 5-phosphatase. The disorder remains incurable, and the pathways underlying the ocular symptoms remain poorly understood, largely due to the lack of appropriate models. In this study, trabecular meshwork cell models of Lowe syndrome were generated to test two distinct gene therapy strategies: a mutation-agnostic OCRL DNA augmentation therapy and a patient-specific CRISPR-mediated gene correction strategy. The results showed that AAV2-OCRL demonstrated the highest transduction efficiency in patient iPSC-derived trabecular meshwork models (iHTM) among the three AAV-OCRL vectors evaluated, establishing it as a promising delivery vector. Targeted CRISPR-based gene therapy restored OCRL enzyme activity and corrected cellular defects in patient iPSC-derived trabecular meshwork cell models. Furthermore, RNA-sequencing analysis of these models revealed dysregulation of extracellular matrix organization, cell adhesion, focal adhesion, and cytoskeletal regulatory pathways, suggesting that disruption of interconnected ECM-adhesion-cytoskeletal networks may contribute to trabecular meshwork dysfunction in Lowe syndrome-associated glaucoma. These findings indicate the feasibility of OCRL gene augmentation and CRISPR-based gene editing in patient-derived ocular models and position AAV2-OCRL as a leading therapeutic candidate for Lowe syndrome.

    View details for DOI 10.1002/advs.77704

    View details for PubMedID 42717497

    View details for PubMedCentralID PMC13558910

  • Primary Cilia of Astrocytes in the Retina in Development and Disease. Investigative ophthalmology & visual science Ning, K., Tran, M., Xia, X., Kowal, T. J., Wang, Q., Lo, C. H., Chen, S., Liu, Z., Li, T., Zhang, F., Wang, W., Sun, Y. 2026; 67 (11): 7

    Abstract

    Defects in primary cilia and ciliary signaling are associated with an array of neurodegenerative diseases. Primary cilia are sensory organelles that transmit and regulate various cellular communication pathways, including the significant Sonic hedgehog and Wnt signal pathways. Extensive studies have shown that neuronal cilia in the central nervous system contribute to early patterning, neuronal maturation, and survival. The behavior of cilia on astrocytes in glaucoma and aging remains poorly understood. This study used rodent and human retinal astrocytes to examine primary cilia and their alteration during aging and disease.Retinal flatmounts from wild-type mice, one macaque, and two humans were immunostained for astrocyte (glial fibrillary acidic protein [GFAP]) and ciliary (Arl13b and gamma-tubulin) markers and analyzed by confocal microscopy. Ciliation was also assessed in models of ocular hypertension and optic nerve crush prepared in 3- and 20-month-old mice.Primary cilia were found in most of the mouse retinal astrocytes (98.81% ± 4.03% in 3-month-old mice and 91.05% ± 9.95% in 20-month-old mice). Interestingly, astrocyte ciliation was significantly reduced in the peripheral retinas of the aged mice. Both human and nonhuman primate retinas expressed primary cilia in bundle-shaped and star-shaped GFAP-positive astrocytes. As a result of alterations in the primary cilia of retinal astrocytes, response processes varied in different glaucoma mouse models, including the ocular hypertension and optic nerve crush models.Aged and diseased mouse retinas demonstrated a novel alteration of their ciliary profile. These findings suggest the possibility that primary cilia contribute to age-associated retinal diseases.

    View details for DOI 10.1167/iovs.67.11.7

    View details for PubMedID 42684095

  • TIGRa: An ultra-compact programmable activator enabling multiplexed and efficient gene regulation. Cell stem cell Liu, Z., Chen, S., Wang, W., Zhang, F., Wang, Q., Walkiewicz, G., Hossen, F., Zhou, J., Wang, Y., Sun, Y. 2026

    Abstract

    Programmable gene activation has broad therapeutic potential but remains constrained by the large effector size, limited multiplexing capacity, and challenges in in vivo delivery. Here, we develop the TIGR-TasR-mediated activator (TIGRa), a compact transcriptional activator derived from the tandem interspaced guide RNA (TIGR)-TIGR-associated protein (TasR) system that is mechanistically distinct from CRISPR-based activators. TIGRa is less than half the size of dSpCas9-based activators while achieving comparable or greater activation efficiency. Its native TIGR array architecture enables efficient multiplexed regulation, supporting simultaneous activation of up to 12 endogenous genes from a single compact construct. TIGRa-mediated multi-gene activation efficiently reprogrammed human fibroblasts into induced pluripotent stem cells. In addition, an all-in-one adeno-associated virus (AAV)-TIGRa vector activated endogenous CaMKII in vivo, promoting retinal ganglion cell survival and preserving visual function in a mouse model of N-methyl-D-aspartic (NMDA)-induced retinal injury. These results establish TIGRa as a compact and multiplexable platform for therapeutic gene regulation and in vivo genetic medicine.

    View details for DOI 10.1016/j.stem.2026.07.008

    View details for PubMedID 42575098

  • High fat diet alters lipidomics and worsens visual outcomes in experimental anterior ischemic optic neuropathy Ahmed, T., Wang, Q., Liu, L., Yang, M., Alkhabaz, A., Wu, H., Shariati, A., Dai, Y., Liao, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2026

    View details for Web of Science ID 001879171400035

  • Matrine Reduces Intraocular Pressure in Corticosteroid-Induced Ocular Hypertensive Mouse Eyes. Investigative ophthalmology & visual science Zhang, Q., Liu, Z., Chen, S., Wang, Q., Lo, C. H., Ning, K., Zhao, J., Shen, Y., Liton, P. B., Sun, Y. 2025; 66 (11): 18

    Abstract

    This study investigates the potential of matrine, a quinolizidine alkaloid, in regulating intraocular pressure (IOP) in normal and corticosteroid-induced ocular hypertension (OHT) mice.Wild-type C57BL/6 mice were randomly divided into normal and OHT groups. The OHT mouse model was established by periocular conjunctival fornix injections of dexamethasone-21-acetate (DEX). IOP was measured at 0.0, 0.5, 1.0, 3.0, and 6.0 hours after matrine treatment in both groups. Aqueous humor (AH) outflow facility was measured using our previously described/validated perfusion system. Anterior segment-optical coherence tomography was used to evaluate morphological changes in the anterior chamber following matrine treatment. Hematoxylin and eosin staining and immunofluorescence staining were used to investigate structural changes.Matrine treatment (50-200 µg/g) decreased the IOP in normal mice in a dose-dependent manner. AH outflow facility in normal mice elevated at 0.5 hours after matrine treatment (100 and 200 µg/g). Additionally, 100 µg/g matrine treatment increased the angle opening distance in the anterior chamber. In DEX-induced OHT mice, matrine (100 and 200 µg/g) reduced the elevated IOP and increased the AH outflow facility. Furthermore, 100 µg/g matrine treatment increased the angle opening distance compared with that of PBS-treated controls. However, matrine (100 µg/g) did not induce significant changes in trabecular meshwork gross morphology or the expression of cell contractility and extracellular matrix markers in OHT mice at 0.5 hours after treatment.Matrine decreased the IOP in the DEX-induced OHT mouse model, highlighting its potential as a therapeutic agent for managing glaucoma, particularly in corticosteroid-associated secondary cases.

    View details for DOI 10.1167/iovs.66.11.18

    View details for PubMedID 40772663

  • Matrine Reduces Intraocular Pressure in Corticosteroid-induced Ocular Hypertensive Mouse Eyes Shen, Y., Zhang, Q., Liu, Z., Chen, S., Wang, Q., Lo, C., Ning, K., Zhao, J., Liton, P. B., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2025

    View details for Web of Science ID 001559176600034

  • Gene therapy for ocular hypertension using hfCas13d-mediated mRNA targeting. PNAS nexus Chen, S., Liu, Z., Lo, C. H., Wang, Q., Ning, K., Zhang, Q., Zhao, J., Shen, Y., Sun, Y. 2025; 4 (6): pgaf168

    Abstract

    Glaucoma is a major global cause of irreversible vision loss. It is marked by elevated intraocular pressure (IOP) and the loss of retinal ganglion cells (RGC). While there are medical and surgical therapies for glaucoma aiming to reduce aqueous humor production or enhance its drainage, these treatments are often inadequate for effectively managing the disease. In this study, we developed a targeted therapy for glaucoma by knocking down two genes associated with aqueous humor production (aquaporin 1 [AQP1] and carbonic anhydrase type 2 [CA2]) using Cas13 RNA editing systems. We demonstrate that hfCas13d-mediated knockdown of AQP1 and CA2 significantly lowers IOP in wild-type mice and in a corticosteroid-induced glaucoma mouse model. We show that the lowered IOP results from decreasing aqueous production without affecting the outflow facility; this treatment also significantly promotes RGC survival as compared with untreated control groups. Therefore, CRISPR-Cas-based gene editing may be an effective treatment to lower IOP for glaucomatous optic neuropathy.

    View details for DOI 10.1093/pnasnexus/pgaf168

    View details for PubMedID 40575705

    View details for PubMedCentralID PMC12199245

  • Increased oxidative stress and inflammation in human and experimental optic nerve stroke Ahmed, T., Liu, L., Wang, Q., Wu, H., Liao, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2025

    View details for Web of Science ID 001558634800002

  • Effect of Brimonidine on Retinal Ganglion Cell Function by in vivo Calcium Imaging of Optic Nerve Crush in Mice. Experimental eye research Li, T., Kowal, T. J., Zhao, J., Li, L., Wang, Q., Ning, K., Lo, C. H., Liu, Z., Shen, Y., Yu, J., Jin, H., Sun, Y. 2025: 110355

    Abstract

    Brimonidine has shown neuroprotective effects in animal studies, but clinical trials failed to demonstrate effective endpoints. Here, we used a newly developed in vivo calcium imaging method to measure RGC function of brimonidine in mice optic nerve crush (ONC) models. To transduce RGCs in vivo, wild-type C57Bl/6j mice were treated with intravitreal AAV2-mSncg-jGCaMP7s, a live-cell Ca2+ tracer. RGCs are defined as 10 subtypes according to different responses to UV light. Mice were treated with topical brimonidine or placebo three times daily for two weeks after ONC. The calcium signals of live-cell RGCs were measured with the Heidelberg cSLO system. Ganglion cell complex (GCC) thickness and IOP were examined at different timepoints after treatment. RGCs were counted after RBPMS immunostaining. Live calcium imaging showed ONC significantly decreased RGC number at 14 days post-ONC compared to controls. The topical brimonidine administration changed calcium signal responses of RGC to UV light in ONC mice. It showed brimonidine partly prevented the decrease of survival ON-RGCs percent after ONC. Single RGC analysis showed a lower conversion percent of ON-RGCs to OFF-RGCs with brimonidine administration after ONC. However, no significant differences in RGC survival, IOP or GCC thickness were noted between eyes treated with brimonidine or placebo. In the acute ONC mice model, in vivo calcium imaging revealed that brimonidine maintained the Ca2+ activation of ON-RGCs to UV stimulation, inhibiting the conversion of survival ON-RGCs to OFF-RGCs. This indicates that ON-RGCs may be more resilient to acute optic nerve injury based on the calcium imaging method.

    View details for DOI 10.1016/j.exer.2025.110355

    View details for PubMedID 40127747

  • dCasMINI-mediated therapy rescues photoreceptors degeneration in a mouse model of retinitis pigmentosa. Science advances Wang, Q., Xu, X., Chen, S., Lu, R., Li, L., Lo, C. H., Liu, Z., Ning, K., Li, T., Kowal, T. J., Wang, B., Hartnett, M. E., Wang, S., Qi, L. S., Sun, Y. 2024; 10 (51): eadn7540

    Abstract

    Retinitis pigmentosa (RP) is characterized by degeneration of rod and cone photoreceptors that progresses to irreversible blindness. Now, there are no mutation-agnostic approaches to treat RP. Here, we utilized a single adeno-associated virus (AAV)-based CRISPR activation system to activate phosphodiesterase 6B (Pde6b) to mitigate the severe degeneration in Pde6anmf363 mice. We demonstrate that transcriptional activation of Pde6b can rescue the loss of Pde6a, with preservation of retinal structure, restoration of electroretinography responses, and improvement of visual function as assessed by optokinetic response and looming-induced escape behaviors. These findings demonstrate the therapeutic potential of a dCasMINI-mediated activation strategy that provides a mutation-independent treatment for retinal degeneration. This study offers a promising therapeutic approach for RP and potentially other forms of genetic diseases.

    View details for DOI 10.1126/sciadv.adn7540

    View details for PubMedID 39693439

    View details for PubMedCentralID PMC11654696

  • All-in-one AAV-mediated Nrl gene inactivation rescues retinal degeneration in Pde6a mice. JCI insight Liu, Z., Chen, S., Lo, C. H., Wang, Q., Sun, Y. 2024

    Abstract

    Retinitis pigmentosa (RP) is a complex group of inherited retinal diseases characterized by progressive death of photoreceptor cells and eventual blindness. Pde6a, which encodes a cGMP-specific phosphodiesterase, is a crucial pathogenic gene for autosomal recessive RP (RP43); there is no effective therapy for this form of RP. The compact CRISPR/SaCas9 system, which can be packaged into a single adeno-associated virus, holds promise for simplifying effective gene therapy. Here, we demonstrated that all-in-one AAV-SaCas9-mediated Nrl gene inactivation can efficiently prevent retinal degeneration in a RP mouse model with Pde6anmf363/nmf363 mutation. We screened single guide RNAs (sgRNAs) capable of efficiently editing mouse Nrl gene in N2a cells and then achieved effective gene editing by using a single AAV to co-deliver SaCas9 and an optimal Nrl-sg2 into the mouse retina. Excitingly, in vivo inactivation of Nrl improved photoreceptor cell survival and rescued retinal function in treated Pde6a deficient mice. Thus, we showed that a practical, gene-independent method, AAV-SaCas9-mediated Nrl inactivation, holds promise for future therapeutic applications in patients with RP.

    View details for DOI 10.1172/jci.insight.178159

    View details for PubMedID 39499900

  • Defective Neurogenesis in Lowe Syndrome is Caused by Mitochondria Loss and Cilia-related Sonic Hedgehog Defects. bioRxiv : the preprint server for biology Lo, C. H., Chen, S., Zhao, J., Liu, Z., Wang, B., Wang, Q., Kowal, T. J., Sun, Y. 2024

    Abstract

    Human brain development is a complex process that requires intricate coordination of multiple cellular and developmental events. Dysfunction of lipid metabolism can lead to neurodevelopmental disorders. Lowe syndrome (LS) is a recessive X-linked disorder associated with proximal tubular renal disease, congenital cataracts and glaucoma, and central nervous system developmental delays. Mutations in OCRL, which encodes an inositol polyphosphate 5-phosphatase, lead to the development of LS. The cellular mechanism responsible for neuronal dysfunction in LS is unknown. Here we show depletion of mitochondrial DNA and decrease in mitochondrial activities result in neuronal differentiation defects. Increased astrocytes, which are secondary responders to neurodegeneration, are observed in neuronal (iN) cells differentiated from Lowe patient-derived iPSCs and an LS mouse model. Inactivation of cilia-related sonic hedgehog signaling, which organizes the pattern of cellular neuronal differentiation, is observed in an OCRL knockout, iN cells differentiated from Lowe patient-derived iPSCs, and an LS mouse model. Taken together, our findings indicate that mitochondrial dysfunction and impairment of the ciliary sonic hedgehog signaling pathway represent a novel pathogenic mechanism underlying the disrupted neuronal differentiation observed in LS.

    View details for DOI 10.1101/2024.11.01.621496

    View details for PubMedID 39553960

    View details for PubMedCentralID PMC11565974

  • Efficient Rescue of Retinal Degeneration in Pde6a Mice by Engineered Base Editing and Prime Editing. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Liu, Z., Chen, S., Davis, A. E., Lo, C. H., Wang, Q., Li, T., Ning, K., Zhang, Q., Zhao, J., Wang, S., Sun, Y. 2024: e2405628

    Abstract

    Retinitis pigmentosa (RP) is a complex spectrum of inherited retinal diseases marked by the gradual loss of photoreceptor cells, ultimately leading to blindness. Among these, mutations in PDE6A, responsible for encoding a cGMP-specific phosphodiesterase, stand out as pivotal in autosomal recessive RP (RP43). Unfortunately, no effective therapy currently exists for this specific form of RP. However, recent advancements in genome editing, such as base editing (BE) and prime editing (PE), offer a promising avenue for precise and efficient gene therapy. Here, it is illustrated that the engineered BE and PE systems, particularly PE, exhibit high efficiency in rescuing a target point mutation with minimal bystander effects in an RP mouse model carrying the Pde6a (c.2009A > G, p.D670G) mutation. The optimized BE and PE systems are first screened in N2a cells and subsequently assessed in electroporated mouse retinas. Notably, the optimal PE system, delivered via dual adeno-associated virus (AAV), precisely corrects the pathogenic mutation with average 9.4% efficiency, with no detectable bystander editing. This correction restores PDE6A protein expression, preserved photoreceptors, and rescued retinal function in Pde6a mice. Therefore, this study offers a proof-of-concept demonstration for the treatment of Pde6a-related retinal degeneration using BE and PE systems.

    View details for DOI 10.1002/advs.202405628

    View details for PubMedID 39297417

  • Efficient prevention of retinal degeneration in <i>Pde6a</i> mice by all-inone AAV-mediated <i>Nrl</i> gene editing Liu, Z., Chen, S., Lo, C., Wang, Q., Sun, Y. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2024

    View details for Web of Science ID 001312227704183