Mitochondrial movement is a feature of all eukaryotic cells. In neurons, the movements of mitochondria are particularly crucial because of the need to match the distribution of mitochondria to the energy requirements of subcellular regions. Axonal transport of mitochondria is thus required to ensure ATP production and Ca++ buffering at sites that are distant from the cell body. Moreover, the distribution of mitochondria will change in response to neural activity and the increased energy demands that activity places on the cell. The present proposal builds on our earlier studies in which we determined that a complex containing the proteins kinesin heavy chain, milton, miro, and O-GlcNAc transferase is needed for (+)-end directed movement of mitochondria. This proposal focuses on the regulation of mitochondrial movement and how it is mediated through members of this complex. Live imaging of mitochondria in rat hippocampal neurons and Drosophila axons is combined with biochemical and genetic studies so as to address mechanistic questions in vivo and in vitro. 1) We examine the significance of Ca++ regulation of mitochondrial motility via the EF hands of miro. 2) We examine the significance of the GTPase domains of miro to mitochondrial movement. 3) Another likely source of regulation is the post-translational modification of milton by O-GlcNAc transferase;this cytoplasmic glycosylating enzyme binds to milton and glycosylates it. We examine the significance of this modification for mitochondrial movement. 4) Finally, we ask how miro can also regulate retrograde movements of mitochondria.

Public Health Relevance

Defects in mitochondrial distribution give rise to peripheral neuropathies including Charcot-Marie-Tooth Disease and may play a role in many neurodegenerative diseases. Our studies are designed to determine the normal means by which mitochondria are distributed in cells and thereby gain insights into potential pathological mechanisms, including the role of mitochondrial movement in responses to stress.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM069808-08
Application #
8321519
Study Section
Synapses, Cytoskeleton and Trafficking Study Section (SYN)
Program Officer
Gindhart, Joseph G
Project Start
2004-09-20
Project End
2014-08-31
Budget Start
2012-09-01
Budget End
2014-08-31
Support Year
8
Fiscal Year
2012
Total Cost
$298,441
Indirect Cost
$126,923
Name
Children's Hospital Boston
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115
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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
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Wang, Xinnan; Schwarz, Thomas L (2009) Imaging axonal transport of mitochondria. Methods Enzymol 457:319-33
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Glater, Elizabeth E; Megeath, Laura J; Stowers, R Steven et al. (2006) Axonal transport of mitochondria requires milton to recruit kinesin heavy chain and is light chain independent. J Cell Biol 173:545-57