Movement of intracellular compartments to their correct locations at precise times is a fundamental property of all cell types. For example, pigment cells, intestinal epithelia, lymphocytes, and neurons, require that specific organelles be targeted to precise locations at the proper time. In each case, myosin V molecular motors play key roles in organelle transport. Long-range movement of organelles occurs on microtubules via kinesin and dynein motors. Notably, the late steps in transport require transfer from kinesin to a myosin V motor, followed by movement on actin to a terminal destination. Regulation of detachment of organelles from myosin V is also critical to their proper localization. Our overall goal is to uncover mechanisms whereby myosin V regulates cellular organization. Similar to specialized cell-types in higher eukaryotes, the yeast Saccharomyces cerevisiae targets organelles to specific locations at precise times. We discovered that in coordination with the cell-cycle, a portion of the yeast vacuole is targeted from the mother cell to the bud. We further discovered that this movement requires the myosin V, Myo2. Moreover, we and others dis- covered that most intracellular movement in yeast occurs solely on actin and requires Myo2. Our recent progress provides strong evidence for the hypothesis that studies of yeast Myo2 will inform our under- standing of mammalian myosin V motors. We identified a conserved binding site for Rab GTPases, and an independent site dedicated to the exocyst subunit Sec15. The Rab GTPases and exocyst are conserved proteins that are required for secretion. That each ofthe sites on Myo2 is conserved strongly suggests that what we learn about how yeast Myo2 attaches and detaches from membranes will be directly applicable to human myosin Va, Vb and Vc. We proposed to use the yeast system to determine the mechanisms that govern myosin V-based transport.
Our aims are to: 1) Determine whether binding of individual Myo2 adaptor proteins are enhanced or inhibited by other Myo2 adaptor proteins. 2) Determine whether the direct interaction of Myo2 with Ypt31/Ypt32, Sec4 and Sec15 plays roles beyond the attachment of Myo2 to secretory vesicles. 3) Determine mechanisms that regulate the detachment of myosin V from cargoes.

Public Health Relevance

Intracellular transport of organelles by myosin V motors is crucial to normal cellular function, and animal physiology. Defects in myosin V based transport cause selected human diseases including neurological disorders. Our overall goal is to determine the mechanisms that regulate myosin V-based transport.

Agency
National Institute of Health (NIH)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37GM062261-15
Application #
8635525
Study Section
No Study Section (in-house review) (NSS)
Program Officer
Gindhart, Joseph G
Project Start
Project End
Budget Start
Budget End
Support Year
15
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Yau, Richard G; Peng, Yutian; Valiathan, Rajeshwari R et al. (2014) Release from myosin V via regulated recruitment of an E3 ubiquitin ligase controls organelle localization. Dev Cell 28:520-33
Jin, Yui; Sultana, Azmiri; Gandhi, Pallavi et al. (2011) Myosin V transports secretory vesicles via a Rab GTPase cascade and interaction with the exocyst complex. Dev Cell 21:1156-70
Sultana, Azmiri; Jin, Yui; Dregger, Carmen et al. (2011) The activation cycle of Rab GTPase Ypt32 reveals structural determinants of effector recruitment and GDI binding. FEBS Lett 585:3520-7
Jin, Yui; Taylor Eves, P; Tang, Fusheng et al. (2009) PTC1 is required for vacuole inheritance and promotes the association of the myosin-V vacuole-specific receptor complex. Mol Biol Cell 20:1312-23
Lipatova, Zhanna; Tokarev, Andrei A; Jin, Yui et al. (2008) Direct interaction between a myosin V motor and the Rab GTPases Ypt31/32 is required for polarized secretion. Mol Biol Cell 19:4177-87