Misregulation of Mitochondrial Motility in Parkinsonian Pathogenesis I set out to understand the regulatory mechanisms underlying mitochondrial transport in cells as my long-term career goal. Mitochondria move and undergo fission and fusion in all eukaryotic cells, but the need to supply mitochondria to the far-flung extremities of neurons creates a particular urgency for mitochondrial transport in neurons. Misregulation of the transport and distribution of mitochondria in axons can be a critical component of neurodegeneration. I propose that the transport of mitochondria is particularly vital for maintaining neuronal function and that even subtle perturbation of their traffic may contribute to neurodegenerative disorders. Starting with a motor/adaptor complex including kinesin-1 heavy chain (KHC), milton and Miro that transports axonal mitochondria anterograde and having elucidated the mechanism how Ca++ regulates mitochondrial motility via this complex (Wang and Schwarz, 2009a), I now would like to investigate the involvement of this complex in neurodegeneration as my immediate goal. Specifically, I propose to focus on PINK1 and Parkin, mutations of which cause Parkinson's disease in humans. Because both proteins can localize to mitochondria and genetically interact, and because PINK1 resides in the outer mitochondrial membrane and interacts with KHC/milton/Miro complex (Zhou et al., 2008;Weihofen et al., 2009), I hypothesize that PINK1 and Parkin also participate in the regulation of mitochondrial transport by regulating KHC/milton/Miro activity, misregulation of which may explain the Parkinsonian neurodegeneration. I therefore propose to look at animal models of Parkinsonism that might involve impaired mitochondria, to determine if mitochondrial transport is abnormal, and to examine the underlying mechanisms. I plan to establish a link between misregulation of mitochondrial motility and Parkinsonian neurodegeneration in my mentored phase here in Children's Hospital Boston and Harvard Medical School, and continue to investigate the underlying mechanisms and the involvement of mitochondrial motility in other neurodegenerative diseases as an independent principal investigator.
Parkinson's disease is one of the most common neurological disorders, and although several disease-causing genes have been identified, the exact pathogenesis is unknown. Robust evidence has suggested mitochondrial abnormalities in the disease, therefore I would like to further investigate the involvement of mitochondrial motility in Parkinsonian neurodegeneration, which will provide a better understanding of the cellular defects and promising cues for therapies.
|Course, Meredith M; Scott, Anna I; Schoor, Carmen et al. (2018) Phosphorylation of MCAD selectively rescues PINK1 deficiencies in behavior and metabolism. Mol Biol Cell 29:1219-1227|
|Course, Meredith M; Hsieh, Chung-Han; Tsai, Pei-I et al. (2017) Live Imaging Mitochondrial Transport in Neurons. Neuromethods 123:49-66|
|Tsai, Pei-I; Papakyrikos, Amanda M; Hsieh, Chung-Han et al. (2017) Drosophila MIC60/mitofilin conducts dual roles in mitochondrial motility and crista structure. Mol Biol Cell 28:3471-3479|
|Tsai, Pei-I; Course, Meredith M; Lovas, Jonathan R et al. (2014) PINK1-mediated phosphorylation of Miro inhibits synaptic growth and protects dopaminergic neurons in Drosophila. Sci Rep 4:6962|
|Lovas, Jonathan R; Wang, Xinnan (2013) The meaning of mitochondrial movement to a neuron's life. Biochim Biophys Acta 1833:184-94|
|Frank, C Andrew; Wang, Xinnan; Collins, Catherine A et al. (2013) New approaches for studying synaptic development, function, and plasticity using Drosophila as a model system. J Neurosci 33:17560-8|
|Wang, Xinnan; Winter, Dominic; Ashrafi, Ghazaleh et al. (2011) PINK1 and Parkin target Miro for phosphorylation and degradation to arrest mitochondrial motility. Cell 147:893-906|