Academic Appointments

Administrative Appointments

  • Associate Professor, Stanford University School of Medicine (2019 - Present)
  • Assistant Professor, Stanford University School of Medicine (2012 - 2019)

Honors & Awards

  • McCormick and Gabilan Faculty Award, Stanford University (2018-2020)
  • Parkinson's seed grant, Stanford (2018-2019)
  • The Archer Award, The Archer Foundation (2016-2018)
  • Biology V, California Institute of Regenerative Medicine (2014-2017)
  • Mechanisms of Illness, Chronic Fatigue Initiative (2014-2015)
  • Klingenstein Fellowship in Neuroscience, Klingenstein Foundation (2013-2018)
  • Michael J. Fox Foundation Grant Target Validation Spring 2013, Michael J. Fox Foundation (2013-2014)
  • Gabilan Junior Faculty Fellow, Stanford University (2012-now)
  • Alfred P. Sloan Research Fellow 2012, Alfred P. Sloan Foundation (2012-2016)
  • William and Bernice E Bumpus Foundation Innovation Award, William and Bernice E Bumpus Foundation (2011-2014)
  • NIH Pathway to Independence (K99/R00), NINDS (2009-2014)

Professional Education

  • Ph.D, University of Cambridge, Genetics, Neurobiology (2007)
  • M.D/MSc., China Medical University, Clinical Medicine and Genetics (2003)


  • Xinnan Wang. "United States Patent 23-1115-US-PRO Compositions and methods for treating glioblastoma", Stanford University
  • Xinnan Wang. "United States Patent AU2020343009A1 Methods and compounds modifying mitochondrial function", Stanford University
  • Xinnan Wang. "United States Patent US2022/041930 A Small Molecule Therapeutic for Friedreich’s Ataxia and Tauopathy", Stanford University
  • Xinnan Wang. "United States Patent US63/228,505 T-Type Calcium Channel Antagonists and Uses Thereof", Stanford University
  • Xinnan Wang. "United States Patent WO2021046322A1 A small molecule therapeutic for Parkinson's disease paired with a biomarker of therapeutic activity", Stanford University

Current Research and Scholarly Interests

Mitochondria move and undergo fission and fusion in all eukaryotic cells. The accurate allocation of mitochondria in neurons is particularly critical due to the significance of mitochondria for ATP supply, Ca++ homeostasis and apoptosis and the importance of these functions to the distal extremities of neurons. In addition, defective mitochondria, which can be highly deleterious to a cell because of their output of reactive oxygen species, need to be repaired by fusing with healthy mitochondria or cleared from the cell. Thus mitochondrial cell biology poses critical questions for all cells, but especially for neurons: how the cell sets up an adequate distribution of the organelle; how it sustains mitochondria in the periphery; and how mitochondria are removed after damage. The goal of my research is to understand the regulatory mechanisms controlling mitochondrial dynamics and function and the mechanisms by which even subtle perturbations of these processes may contribute to neurodegenerative disorders.

Stanford Advisees

Graduate and Fellowship Programs

All Publications

  • Mitochondrial calcium transport during autophagy initiation Mitochondrial Communications Chandra, S., Katiyar, P., Durairaj, A. S., Wang, X. 2024; 2 (2): 14-20
  • A mitochondrial inside-out iron-calcium signal reveals drug targets for Parkinson's disease. Cell reports Bharat, V., Durairaj, A. S., Vanhauwaert, R., Li, L., Muir, C. M., Chandra, S., Kwak, C. S., Le Guen, Y., Nandakishore, P., Hsieh, C. H., Rensi, S. E., Altman, R. B., Greicius, M. D., Feng, L., Wang, X. 2023; 42 (12): 113544


    Dysregulated iron or Ca2+ homeostasis has been reported in Parkinson's disease (PD) models. Here, we discover a connection between these two metals at the mitochondria. Elevation of iron levels causes inward mitochondrial Ca2+ overflow, through an interaction of Fe2+ with mitochondrial calcium uniporter (MCU). In PD neurons, iron accumulation-triggered Ca2+ influx across the mitochondrial surface leads to spatially confined Ca2+ elevation at the outer mitochondrial membrane, which is subsequently sensed by Miro1, a Ca2+-binding protein. A Miro1 blood test distinguishes PD patients from controls and responds to drug treatment. Miro1-based drug screens in PD cells discover Food and Drug Administration-approved T-type Ca2+-channel blockers. Human genetic analysis reveals enrichment of rare variants in T-type Ca2+-channel subtypes associated with PD status. Our results identify a molecular mechanism in PD pathophysiology and drug targets and candidates coupled with a convenient stratification method.

    View details for DOI 10.1016/j.celrep.2023.113544

    View details for PubMedID 38060381

  • Mitochondrial heterogeneity and homeostasis through the lens of a neuron. Nature metabolism Pekkurnaz, G., Wang, X. 2022; 4 (7): 802-812


    Mitochondria are vital organelles with distinct morphological features and functional properties. The dynamic network of mitochondria undergoes structural and functional adaptations in response to cell-type-specific metabolic demands. Even within the same cell, mitochondria can display wide diversity and separate into functionally distinct subpopulations. Mitochondrial heterogeneity supports unique subcellular functions and is crucial to polarized cells, such as neurons. The spatiotemporal metabolic burden within the complex shape of a neuron requires precisely localized mitochondria. By travelling great lengths throughout neurons and experiencing bouts of immobility, mitochondria meet distant local fuel demands. Understanding mitochondrial heterogeneity and homeostasis mechanisms in neurons provides a framework to probe their significance to many other cell types. Here, we put forth an outline of the multifaceted role of mitochondria in regulating neuronal physiology and cellular functions more broadly.

    View details for DOI 10.1038/s42255-022-00594-w

    View details for PubMedID 35817853

    View details for PubMedCentralID 5605817

  • A mitochondrial membrane-bridging machinery mediates signal transduction of intramitochondrial oxidation. Nature metabolism Li, L., Conradson, D. M., Bharat, V., Kim, M. J., Hsieh, C., Minhas, P. S., Papakyrikos, A. M., Durairaj, A. S., Ludlam, A., Andreasson, K. I., Partridge, L., Cianfrocco, M. A., Wang, X. 2021


    Mitochondria are the main site for generating reactive oxygen species, which are key players in diverse biological processes. However, the molecular pathways of redox signal transduction from the matrix to the cytosol are poorly defined. Here we report an inside-out redox signal of mitochondria. Cysteine oxidation of MIC60, an inner mitochondrial membrane protein, triggers the formation of disulfide bonds and the physical association of MIC60 with Miro, an outer mitochondrial membrane protein. The oxidative structural change of this membrane-crossing complex ultimately elicits cellular responses that delay mitophagy, impair cellular respiration and cause oxidative stress. Blocking the MIC60-Miro interaction or reducing either protein, genetically or pharmacologically, extends lifespan and health-span of healthy fruit flies, and benefits multiple models of Parkinson's disease and Friedreich's ataxia. Our discovery provides a molecular basis for common treatment strategies against oxidative stress.

    View details for DOI 10.1038/s42255-021-00443-2

    View details for PubMedID 34504353

  • Miro1 Impairment in a Parkinson's At-Risk Cohort. Frontiers in molecular neuroscience Nguyen, D., Bharat, V., Conradson, D. M., Nandakishore, P., Wang, X. 2021; 14: 734273


    There is a lack of reliable molecular markers for Parkinson's disease (PD) patients and at-risk individuals. The detection of the pre-symptomatic population of PD will empower more effective clinical intervention to delay or prevent disease onset. We have previously found that the mitochondrial protein Miro1 is resistant to mitochondrial depolarization-induced degradation in fibroblasts from a large number of PD patients and several at-risk individuals. Therefore, Miro1 has the potential to molecularly label PD populations. In order to determine whether Miro1 could serve as a molecular marker for the risk of PD, here we examine the Miro1 response to mitochondrial depolarization by biochemical approaches in induced pluripotent stem cells from a cohort of at-risk individuals. Our results show that the Miro1 phenotype is significantly associated with PD risk. We propose that Miro1 is a promising molecular marker for detecting both PD and at-risk populations. Tracking this Miro1 marker could aid in diagnosis and Miro1-based drug discoveries.

    View details for DOI 10.3389/fnmol.2021.734273

    View details for PubMedID 34434090

  • Metaxins are core components of mitochondrial transport adaptor complexes. Nature communications Zhao, Y., Song, E., Wang, W., Hsieh, C., Wang, X., Feng, W., Wang, X., Shen, K. 2021; 12 (1): 83


    Trafficking of mitochondria into dendrites and axons plays an important role in the physiology and pathophysiology of neurons. Mitochondrial outer membrane protein Miro and adaptor proteins TRAKs/Milton link mitochondria to molecular motors. Here we show that metaxins MTX-1 and MTX-2 contribute to mitochondrial transport into both dendrites and axons of C. elegans neurons. MTX1/2 bind to MIRO-1 and kinesin light chain KLC-1, forming a complex to mediate kinesin-1-based movement of mitochondria, in which MTX-1/2 are essential and MIRO-1 plays an accessory role. We find that MTX-2, MIRO-1, and TRAK-1 form another distinct adaptor complex to mediate dynein-based transport. Additionally, we show that failure of mitochondrial trafficking in dendrites causes age-dependent dendrite degeneration. We propose that MTX-2 and MIRO-1 form the adaptor core for both motors, while MTX-1 and TRAK-1 specify each complex for kinesin-1 and dynein, respectively. MTX-1 and MTX-2 are also required for mitochondrial transport in human neurons, indicative of their evolutionarily conserved function.

    View details for DOI 10.1038/s41467-020-20346-2

    View details for PubMedID 33397950

  • Mitochondrial Defects in Fibroblasts of Pathogenic MAPT Patients. Frontiers in cell and developmental biology Bharat, V., Hsieh, C. H., Wang, X. 2021; 9: 765408


    Mutations in MAPT gene cause multiple neurological disorders, including frontal temporal lobar degeneration and parkinsonism. Increasing evidence indicates impaired mitochondrial homeostasis and mitophagy in patients and disease models of pathogenic MAPT. Here, using MAPT patients' fibroblasts as a model, we report that disease-causing MAPT mutations compromise early events of mitophagy. By employing biochemical and mitochondrial assays we discover that upon mitochondrial depolarization, the recruitment of LRRK2 and Parkin to mitochondria and degradation of the outer mitochondrial membrane protein Miro1 are disrupted. Using high resolution electron microscopy, we reveal that the contact of mitochondrial membranes with ER and cytoskeleton tracks is dissociated following mitochondrial damage. This membrane dissociation is blocked by a pathogenic MAPT mutation. Furthermore, we provide evidence showing that tau protein, which is encoded by MAPT gene, interacts with Miro1 protein, and this interaction is abolished by pathogenic MAPT mutations. Lastly, treating fibroblasts of a MAPT patient with a small molecule promotes Miro1 degradation following depolarization. Altogether, our results show molecular defects in a peripheral tissue of patients and suggest that targeting mitochondrial quality control may have a broad application for future therapeutic intervention.

    View details for DOI 10.3389/fcell.2021.765408

    View details for PubMedID 34805172

    View details for PubMedCentralID PMC8595217

  • Precision Neurology for Parkinson's Disease: Coupling Miro1-Based Diagnosis with Drug Discovery. Movement disorders : official journal of the Movement Disorder Society Bharat, V., Wang, X. 2020


    Parkinson's disease (PD) is a debilitating movement disorder, significantly afflicting the aging population. Efforts to develop an effective treatment have been challenged by the lack of understanding of the pathological mechanisms underlying neurodegeneration. We have shown that Miro1, an outer mitochondrial membrane protein, situates at the intersection of the complex genetic and functional network of PD. Removing Miro1 from the surface of damaged mitochondria is a prerequisite for mitochondrial clearance via mitophagy. Parkinson's proteins PINK1, Parkin, and LRRK2 are the molecular helpers to remove Miro1 from dysfunctional mitochondria destined for mitophagy. We have found a delay in clearing Miro1 and initiating mitophagy in postmortem brains and induced pluripotent stem cell-derived neurons from PD patients harboring mutations in LRRK2, PINK1, or Parkin, or from sporadic PD patients with no known mutations. In addition, we have shown that reducing Miro1 by both genetic and pharmacological approaches can correct this Miro1 phenotype and rescue Parkinson's-relevant phenotypes in human neurons and fly PD models. These results suggest that the Miro1 defect may be a common denominator for PD, and compounds that reduce Miro1 promise a new class of drugs to battle PD. We propose to couple this Miro1 phenotype with Miro1-based drug discovery in future therapeutic studies, which could significantly improve the success of clinical trials. © 2020 International Parkinson and Movement Disorder Society.

    View details for DOI 10.1002/mds.28194

    View details for PubMedID 32710675

  • Drosophila VCP/p97 Mediates Dynein-Dependent Retrograde Mitochondrial Motility in Axons. Frontiers in cell and developmental biology Gonzalez, A. E., Wang, X. n. 2020; 8: 256


    Valosin-containing protein (VCP), also called p97, is an evolutionarily conserved and ubiquitously expressed ATPase with diverse cellular functions. Dominant mutations in VCP are found in a late-onset multisystem degenerative proteinopathy. The neurological manifestations of the disorder include frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). In these patients, long motor neuron axons could be particularly susceptible to defects in axonal transport. However, whether VCP has a physiological function in maintaining axonal transport and whether this role is impaired by disease-causing mutations remains elusive. Here, by employing live-imaging methods in Drosophila larval axons and performing genetic interaction experiments, we discover that VCP regulates the axonal transport of mitochondria. Downregulation of VCP enhances the retrograde transport of mitochondria and reduces the density of mitochondria in larval axons. This unidirectional motility phenotype is rescued by removing one copy of the retrograde motor dynein heavy chain (DHC), or elevating Miro which facilitates anterograde mitochondrial movement by interacting with the anterograde motor kinesin heavy chain (KHC). Importantly, Miro upregulation also significantly improves ATP production of VCP mutant larvae. We investigate human VCP pathogenic mutations in our fly system. We find that expressing these mutations affects mitochondrial transport in the same way as knocking down VCP. Our results reveal a new role of VCP in mediating axonal mitochondrial transport, and provide evidence implicating impaired mitochondrial motility in the pathophysiology of VCP-relevant neurodegenerative diseases.

    View details for DOI 10.3389/fcell.2020.00256

    View details for PubMedID 32373611

    View details for PubMedCentralID PMC7186335

  • Drosophila PTPMT1 Has a Function in Tracheal Air Filling. iScience Papakyrikos, A. M., Kim, M. J., Wang, X. n. 2020; 23 (7): 101285


    The fly trachea is the equivalent of the mammalian lung and is a useful model for human respiratory diseases. However, little is known about the molecular mechanisms underlying tracheal air filling during larval development. In this study, we discover that PTPMT1 has a function in tracheal air filling. PTPMT1 is a widely conserved, ubiquitously expressed mitochondrial phosphatase. To reveal PTPMT1's functions in genetically tractable invertebrates and whether those functions are tissue specific, we generate a Drosophila model of PTPMT1 depletion. We find that fly PTPMT1 mutants show impairments in tracheal air filling and subsequent activation of innate immune responses. On a cellular level, these defects are preceded by aggregation of mitochondria within the tracheal epithelial cells. Our work demonstrates a cell-type-specific role for PTPMT1 in fly tracheal epithelial cells to support air filling and to prevent immune activation. The establishment of this model will facilitate exploration of PTPMT1's physiological functions in vivo.

    View details for DOI 10.1016/j.isci.2020.101285

    View details for PubMedID 32629421

  • Surveillance and transportation of mitochondria in neurons CURRENT OPINION IN NEUROBIOLOGY Vanhauwaert, R., Bharat, V., Wang, X. 2019; 57: 87–93
  • Miro1 Marks Parkinson's Disease Subset and Miro1 Reducer Rescues Neuron Loss in Parkinson's Models. Cell metabolism Hsieh, C. H., Li, L. n., Vanhauwaert, R. n., Nguyen, K. T., Davis, M. D., Bu, G. n., Wszolek, Z. K., Wang, X. n. 2019


    The identification of molecular targets and pharmacodynamic markers for Parkinson's disease (PD) will empower more effective clinical management and experimental therapies. Miro1 is localized on the mitochondrial surface and mediates mitochondrial motility. Miro1 is removed from depolarized mitochondria to facilitate their clearance via mitophagy. Here, we explore the clinical utility of Miro1 for detecting PD and for gauging potential treatments. We measure the Miro1 response to mitochondrial depolarization using biochemical assays in skin fibroblasts from a broad spectrum of PD patients and discover that more than 94% of the patients' fibroblast cell lines fail to remove Miro1 following depolarization. We identify a small molecule that can repair this defect of Miro1 in PD fibroblasts. Treating patient-derived neurons and fly models with this compound rescues the locomotor deficits and dopaminergic neurodegeneration. Our results indicate that tracking this Miro1 marker and engaging in Miro1-based therapies could open new avenues to personalized medicine.

    View details for DOI 10.1016/j.cmet.2019.08.023

    View details for PubMedID 31564441

  • Alpha-synuclein delays mitophagy and targeting Miro rescues neuron loss in Parkinson's models. Acta neuropathologica Shaltouki, A., Hsieh, C., Kim, M. J., Wang, X. 2018


    Alpha-synuclein is a component of Lewy bodies, the pathological hallmark of Parkinson's disease (PD), and is also mutated in familial PD. Here, by extensively analyzing PD patient brains and neurons, and fly models, we show that alpha-synuclein accumulation results in upregulation of Miro protein levels. Miro is a motor/adaptor on the outer mitochondrial membrane that mediates mitochondrial motility, and is removed from damaged mitochondria to facilitate mitochondrial clearance via mitophagy. PD patient neurons abnormally accumulate Miro on the mitochondrial surface leading to delayed mitophagy. Partial reduction of Miro rescues mitophagy phenotypes and neurodegeneration in human neurons and flies. Upregulation of Miro by alpha-synuclein requires an interaction via the N-terminus of alpha-synuclein. Our results highlight the importance of mitochondria-associated alpha-synuclein in human disease, and present Miro as a novel therapeutic target.

    View details for PubMedID 29923074

  • PINK1 Phosphorylates MIC60/Mitofilin to Control Structural Plasticity of Mitochondrial Crista Junctions. Molecular cell Tsai, P. I., Lin, C. H., Hsieh, C. H., Papakyrikos, A. M., Kim, M. J., Napolioni, V. n., Schoor, C. n., Couthouis, J. n., Wu, R. M., Wszolek, Z. K., Winter, D. n., Greicius, M. D., Ross, O. A., Wang, X. n. 2018


    Mitochondrial crista structure partitions vital cellular reactions and is precisely regulated by diverse cellular signals. Here, we show that, in Drosophila, mitochondrial cristae undergo dynamic remodeling among distinct subcellular regions and the Parkinson's disease (PD)-linked Ser/Thr kinase PINK1 participates in their regulation. Mitochondria increase crista junctions and numbers in selective subcellular areas, and this remodeling requires PINK1 to phosphorylate the inner mitochondrial membrane protein MIC60/mitofilin, which stabilizes MIC60 oligomerization. Expression of MIC60 restores crista structure and ATP levels of PINK1-null flies and remarkably rescues their behavioral defects and dopaminergic neurodegeneration. In an extension to human relevance, we discover that the PINK1-MIC60 pathway is conserved in human neurons, and expression of several MIC60 coding variants in the mitochondrial targeting sequence found in PD patients in Drosophila impairs crista junction formation and causes locomotion deficits. These findings highlight the importance of maintenance and plasticity of crista junctions to cellular homeostasis in vivo.

    View details for PubMedID 29456190

  • Phosphorylation of MCAD selectively rescuesPINK1deficiencies in behavior and metabolism. Molecular biology of the cell Course, M. M., Scott, A. I., Schoor, C. n., Hsieh, C. H., Papakyrikos, A. M., Winter, D. n., Cowan, T. M., Wang, X. n. 2018


    PINK1 is a mitochondria-targeted kinase, whose mutations are a cause of Parkinson's disease. We set out to better understand PINK1's effects on mitochondrial proteinsin vivoUsing an unbiased phosphoproteomic screen inDrosophila, we found that PINK1 mediates the phosphorylation of MCAD, a mitochondrial matrix protein critical to fatty acid metabolism. By mimicking phosphorylation of this protein in aPINK1null background, we restoredPINK1null's climbing, flight, thorax, and wing deficiencies. Due to MCAD's role in fatty acid metabolism, we examined the metabolic profile ofPINK1null flies, where we uncovered significant disruptions in both acylcarnitines and amino acids. Some of these disruptions were rescued by phosphorylation of MCAD, consistent with MCAD's rescue ofPINK1null's organismal phenotypes. Our work validates and extends the current knowledge of PINK1, identifies a novel function of MCAD, and illuminates the need for and effectiveness of metabolic profiling in models of neurodegenerative disease.

    View details for PubMedID 29563254

  • Live Imaging Mitochondrial Transport in Neurons. Neuromethods Course, M. M., Hsieh, C. H., Tsai, P. I., Codding-Bui, J. A., Shaltouki, A., Wang, X. 2017; 123: 49-66


    Mitochondria are among a cell's most vital organelles. They not only produce the majority of the cell's ATP but also play a key role in Ca2+ buffering and apoptotic signaling. While proper allocation of mitochondria is critical to all cells, it is particularly important for the highly polarized neurons. Because mitochondria are mainly synthesized in the soma, they must be transported long distances to be distributed to the far-flung reaches of the neuron-up to 1 m in the case of some human motor neurons. Furthermore, damaged mitochondria can be detrimental to neuronal health, causing oxidative stress and even cell death, therefore the retrograde transport of damaged mitochondria back to the soma for proper disposal, as well as the anterograde transport of fresh mitochondria from the soma to repair damage, are equally critical. Intriguingly, errors in mitochondrial transport have been increasingly implicated in neurological disorders. Here, we describe how to investigate mitochondrial transport in three complementary neuronal systems: cultured induced pluripotent stem cell-derived neurons, cultured rat hippocampal and cortical neurons, and Drosophila larval neurons in vivo. These models allow us to uncover the molecular and cellular mechanisms underlying transport issues that may occur under physiological or pathological conditions.

    View details for DOI 10.1007/978-1-4939-6890-9_3

    View details for PubMedID 29977105

    View details for PubMedCentralID PMC6029877

  • Drosophila MIC60/Mitofilin Conducts Dual Roles in Mitochondrial Motility and Crista Structure. Molecular biology of the cell Tsai, P. I., Papakyrikos, A. M., Hsieh, C. H., Wang, X. n. 2017


    MIC60/mitofilin constitutes a hetero-oligomeric complex on the inner mitochondrial membranes to maintain crista structure. However, little is known about its physiological functions. Here, by characterizing Drosophila MIC60 mutants, we define its roles in vivo We discover that MIC60 performs dual functions to maintain mitochondrial homeostasis. In addition to its canonical role in crista membrane structure, MIC60 regulates mitochondrial motility, likely by influencing protein levels of the outer mitochondrial membrane protein Miro that anchors mitochondria to the microtubule motors. Loss of MIC60 causes loss of Miro and mitochondrial arrest. At a cellular level, loss of MIC60 disrupts synaptic structure and function at the neuromuscular junctions. The double roles of MIC60 in both mitochondrial crista structure and motility position it as a crucial player for cellular integrity and survival.

    View details for PubMedID 28904209

  • Destructive cellular paths underlying familial and sporadic Parkinson disease converge on mitophagy AUTOPHAGY Wang, X. 2017; 13 (11): 1998-1999


    The knowledge gap separating the molecular and cellular underpinnings of Parkinson disease (PD) and its pathology hinders treatment innovation. Adding to this difficulty is the lack of a reliable biomarker for PD. Our previous studies identify a link of 2 PD proteins, PINK1/PRKN Parkin to a mitochondrial motor adaptor RHOT1/Miro-1, which mediates mitochondrial motility and mitophagy. Here we review our recent paper showing that a third PD protein, LRRK2, also targets RHOT1 and regulates mitophagy, and pathogenic LRRK2 disrupts this function. Notably, we discover impairments in RHOT1 and mitophagy in sporadic PD patients with no known genetic backgrounds, pointing to RHOT1-mediated mitophagy as a convergent pathway in PD. This novelty opens new doors in PD research toward RHOT1-based therapy and biomarker development.

    View details for DOI 10.1080/15548627.2017.1327511

    View details for Web of Science ID 000418882900016

    View details for PubMedID 28598236

    View details for PubMedCentralID PMC5788483

  • Functional Impairment in Miro Degradation and Mitophagy Is a Shared Feature in Familial and Sporadic Parkinson's Disease. Cell stem cell Hsieh, C., Shaltouki, A., Gonzalez, A. E., Bettencourt Da Cruz, A., Burbulla, L. F., St Lawrence, E., Schüle, B., Krainc, D., Palmer, T. D., Wang, X. 2016


    Mitochondrial movements are tightly controlled to maintain energy homeostasis and prevent oxidative stress. Miro is an outer mitochondrial membrane protein that anchors mitochondria to microtubule motors and is removed to stop mitochondrial motility as an early step in the clearance of dysfunctional mitochondria. Here, using human induced pluripotent stem cell (iPSC)-derived neurons and other complementary models, we build on a previous connection of Parkinson's disease (PD)-linked PINK1 and Parkin to Miro by showing that a third PD-related protein, LRRK2, promotes Miro removal by forming a complex with Miro. Pathogenic LRRK2G2019S disrupts this function, delaying the arrest of damaged mitochondria and consequently slowing the initiation of mitophagy. Remarkably, partial reduction of Miro levels in LRRK2G2019S human neuron and Drosophila PD models rescues neurodegeneration. Miro degradation and mitochondrial motility are also impaired in sporadic PD patients. We reveal that prolonged retention of Miro, and the downstream consequences that ensue, may constitute a central component of PD pathogenesis.

    View details for DOI 10.1016/j.stem.2016.08.002

    View details for PubMedID 27618216

    View details for PubMedCentralID PMC5135570

  • Elevated Energy Production in Chronic Fatigue Syndrome Patients. Journal of nature and science Lawson, N., Hsieh, C., March, D., Wang, X. 2016; 2 (10)


    Chronic Fatigue Syndrome (CFS) is a debilitating disease characterized by physical and mental exhaustion. The underlying pathogenesis is unknown, but impairments in certain mitochondrial functions have been found in some CFS patients. To thoroughly reveal mitochondrial deficiencies in CFS patients, here we examine the key aspects of mitochondrial function in blood cells from a paired CFS patient-control series. Surprisingly, we discover that in patients the ATP levels are higher and mitochondrial cristae are more condensed compared to their paired controls, while the mitochondrial crista length, mitochondrial size, shape, density, membrane potential, and enzymatic activities of the complexes in the electron transport chain remain intact. We further show that the increased ATP largely comes from non-mitochondrial sources. Our results indicate that the fatigue symptom in this cohort of patients is unlikely caused by lack of ATP and severe mitochondrial malfunction. On the contrary, it might be linked to a pathological mechanism by which more ATP is produced by non-mitochondrial sources.

    View details for PubMedID 27747291

    View details for PubMedCentralID PMC5065105

  • Transporting mitochondria in neurons. F1000Research Course, M. M., Wang, X. 2016; 5


    Neurons demand vast and vacillating supplies of energy. As the key contributors of this energy, as well as primary pools of calcium and signaling molecules, mitochondria must be where the neuron needs them, when the neuron needs them. The unique architecture and length of neurons, however, make them a complex system for mitochondria to navigate. To add to this difficulty, mitochondria are synthesized mainly in the soma, but must be transported as far as the distant terminals of the neuron. Similarly, damaged mitochondria-which can cause oxidative stress to the neuron-must fuse with healthy mitochondria to repair the damage, return all the way back to the soma for disposal, or be eliminated at the terminals. Increasing evidence suggests that the improper distribution of mitochondria in neurons can lead to neurodegenerative and neuropsychiatric disorders. Here, we will discuss the machinery and regulatory systems used to properly distribute mitochondria in neurons, and how this knowledge has been leveraged to better understand neurological dysfunction.

    View details for DOI 10.12688/f1000research.7864.1

    View details for PubMedID 27508065

    View details for PubMedCentralID PMC4955021

  • PINK1-mediated phosphorylation of Miro inhibits synaptic growth and protects dopaminergic neurons in Drosophila. Scientific reports Tsai, P., Course, M. M., Lovas, J. R., Hsieh, C., Babic, M., Zinsmaier, K. E., Wang, X. 2014; 4: 6962-?


    Mutations in the mitochondrial Ser/Thr kinase PINK1 cause Parkinson's disease. One of the substrates of PINK1 is the outer mitochondrial membrane protein Miro, which regulates mitochondrial transport. In this study, we uncovered novel physiological functions of PINK1-mediated phosphorylation of Miro, using Drosophila as a model. We replaced endogenous Drosophila Miro (DMiro) with transgenically expressed wildtype, or mutant DMiro predicted to resist PINK1-mediated phosphorylation. We found that the expression of phospho-resistant DMiro in a DMiro null mutant background phenocopied a subset of phenotypes of PINK1 null. Specifically, phospho-resistant DMiro increased mitochondrial movement and synaptic growth at larval neuromuscular junctions, and decreased the number of dopaminergic neurons in adult brains. Therefore, PINK1 may inhibit synaptic growth and protect dopaminergic neurons by phosphorylating DMiro. Furthermore, muscle degeneration, swollen mitochondria and locomotor defects found in PINK1 null flies were not observed in phospho-resistant DMiro flies. Thus, our study established an in vivo platform to define functional consequences of PINK1-mediated phosphorylation of its substrates.

    View details for DOI 10.1038/srep06962

    View details for PubMedID 25376463

    View details for PubMedCentralID PMC4223694

  • The meaning of mitochondrial movement to a neuron's life BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH Lovas, J. R., Wang, X. 2013; 1833 (1): 184-194


    Cells precisely regulate mitochondrial movement in order to balance energy needs and avoid cell death. Neurons are particularly susceptible to disturbance of mitochondrial motility and distribution due to their highly extended structures and specialized function. Regulation of mitochondrial motility plays a vital role in neuronal health and death. Here we review the current understanding of regulatory mechanisms that govern neuronal mitochondrial transport and probe their implication in health and disease. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.

    View details for DOI 10.1016/j.bbamcr.2012.04.007

    View details for Web of Science ID 000313932100019

    View details for PubMedID 22548961

    View details for PubMedCentralID PMC3413748

  • PINK1 and Parkin Target Miro for Phosphorylation and Degradation to Arrest Mitochondrial Motility CELL Wang, X., Winter, D., Ashrafi, G., Schlehe, J., Wong, Y. L., Selkoe, D., Rice, S., Steen, J., LaVoie, M. J., Schwarz, T. L. 2011; 147 (4): 893-906


    Cells keep their energy balance and avoid oxidative stress by regulating mitochondrial movement, distribution, and clearance. We report here that two Parkinson's disease proteins, the Ser/Thr kinase PINK1 and ubiquitin ligase Parkin, participate in this regulation by arresting mitochondrial movement. PINK1 phosphorylates Miro, a component of the primary motor/adaptor complex that anchors kinesin to the mitochondrial surface. The phosphorylation of Miro activates proteasomal degradation of Miro in a Parkin-dependent manner. Removal of Miro from the mitochondrion also detaches kinesin from its surface. By preventing mitochondrial movement, the PINK1/Parkin pathway may quarantine damaged mitochondria prior to their clearance. PINK1 has been shown to act upstream of Parkin, but the mechanism corresponding to this relationship has not been known. We propose that PINK1 phosphorylation of substrates triggers the subsequent action of Parkin and the proteasome.

    View details for DOI 10.1016/j.cell.2011.10.018

    View details for Web of Science ID 000296902300021

    View details for PubMedID 22078885

  • The Mechanism of Ca2+-Dependent Regulation of Kinesin-Mediated Mitochondrial Motility CELL Wang, X., Schwarz, T. L. 2009; 136 (1): 163-174


    Mitochondria are mobile organelles and cells regulate mitochondrial movement in order to meet the changing energy needs of each cellular region. Ca(2+) signaling, which halts both anterograde and retrograde mitochondrial motion, serves as one regulatory input. Anterograde mitochondrial movement is generated by kinesin-1, which interacts with the mitochondrial protein Miro through an adaptor protein, milton. We show that kinesin is present on all axonal mitochondria, including those that are stationary or moving retrograde. We also show that the EF-hand motifs of Miro mediate Ca(2+)-dependent arrest of mitochondria and elucidate the regulatory mechanism. Rather than dissociating kinesin-1 from mitochondria, Ca(2+)-binding permits Miro to interact directly with the motor domain of kinesin-1, preventing motor/microtubule interactions. Thus, kinesin-1 switches from an active state in which it is bound to Miro only via milton, to an inactive state in which direct binding to Miro prevents its interaction with microtubules. Disrupting Ca(2+)-dependent regulation diminishes neuronal resistance to excitotoxicity.

    View details for DOI 10.1016/j.cell.2008.11.046

    View details for Web of Science ID 000262318400023

    View details for PubMedID 19135897



    Neuronal mitochondria need to be transported and distributed in axons and dendrites in order to ensure an adequate energy supply and provide sufficient Ca(2+) buffering in each portion of these highly extended cells. Errors in mitochondrial transport are implicated in neurodegenerative diseases. Here we present useful tools to analyze axonal transport of mitochondria both in vitro in cultured rat neurons and in vivo in Drosophila larval neurons. These methods enable investigators to take advantage of both systems to study the properties of mitochondrial motility under normal or pathological conditions.

    View details for DOI 10.1016/S0076-6879(09)05018-6

    View details for Web of Science ID 000266544100018

    View details for PubMedID 19426876

  • Drosophila spichthyin inhibits BMP signaling and regulates synaptic growth and axonal microtubules NATURE NEUROSCIENCE Wang, X., Shaw, R., Tsang, H. T., Reid, E., O'Kane, C. J. 2007; 10 (2): 177-185


    To understand the functions of NIPA1, mutated in the neurodegenerative disease hereditary spastic paraplegia, and of ichthyin, mutated in autosomal recessive congenital ichthyosis, we have studied their Drosophila melanogaster ortholog, spichthyin (Spict). Spict is found on early endosomes. Loss of Spict leads to upregulation of bone morphogenetic protein (BMP) signaling and expansion of the neuromuscular junction. BMP signaling is also necessary for a normal microtubule cytoskeleton and axonal transport; analysis of loss- and gain-of-function phenotypes indicate that Spict may antagonize this function of BMP signaling. Spict interacts with BMP receptors and promotes their internalization from the plasma membrane, implying that it inhibits BMP signaling by regulating BMP receptor traffic. This is the first demonstration of a role for a hereditary spastic paraplegia protein or ichthyin family member in a specific signaling pathway, and implies disease mechanisms for hereditary spastic paraplegia that involve dependence of the microtubule cytoskeleton on BMP signaling.

    View details for DOI 10.1038/nn1841

    View details for Web of Science ID 000244175200012

    View details for PubMedID 17220882