Amoeboid cell motility, a property of many eukaryotic cells, plays a key role in physiological processes such as inflammation, wound healing, neuronal targeting, and metastatic invasion. The purpose of this proposal is to investigate the molecular mechanism of cell crawling using the simple, specialized sperm of the nematode, Ascaris suum, as an experimental system. These cells display the same motile behavior as conventional crawling cells but lack the actin machinery usually associated with cell migration. Instead, the motility apparatus of sperm is based on major sperm protein (MSP) filaments that assemble along the leading edge and disassemble at the base of the lamellipod. These unique filaments have no structural polarity indicating that molecular motor proteins are not required for sperm motility. The coupling of MSP cytoskeletal dynamics to locomotion suggests a """"""""push-pull"""""""" mechanism for movement in which forces for leading edge protrusion and cell body retraction are produced at opposite ends of the lamellipod and linked reciprocally to the assembly status of the cytoskeleton. The push-pull model will be evaluated by characterizing the components of the motility apparatus and integrating this information to define how the cell machinery produces movement. Structural studies will be extended to determine the orientation of the MSP subunits in filaments and to define the interactions that promote intrinsic bundling of filaments into larger arrays. Based on this information MSP mutants will be constructed to study the contributions of filament polymerization and bundling to generating the forces for movement. Biochemical and molecular methods will be used to analyze the membrane and cytosolic proteins required to nucleate MSP polymerization at the leading edge and explore the roles of pH and phosphorylation in regulating this process. The hypothesis that the force for cell body retraction is produced by deswelling of the MSP cytoskeleton will be tested by defining conditions that induce shrinkage of MSP filament gels in vitro and examining the organization of the cytoskeleton at the base of the lamellipod. The long term goal of this project is to define the mechanism of sperm locomotion so that comparison of actin- and MSP-based systems can be used to understand the basic principles of amoeboid cell motility.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
2R37GM029994-20
Application #
6384152
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Deatherage, James F
Project Start
1982-01-01
Project End
2006-06-30
Budget Start
2001-07-01
Budget End
2002-06-30
Support Year
20
Fiscal Year
2001
Total Cost
$348,440
Indirect Cost
Name
Florida State University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
020520466
City
Tallahassee
State
FL
Country
United States
Zip Code
32306
Roberts, Thomas M; Stewart, Murray (2012) Role of major sperm protein (MSP) in the protrusion and retraction of Ascaris sperm. Int Rev Cell Mol Biol 297:265-93
Shimabukuro, Katsuya; Noda, Naoki; Stewart, Murray et al. (2011) Reconstitution of amoeboid motility in vitro identifies a motor-independent mechanism for cell body retraction. Curr Biol 21:1727-31
Schreiber, Christian H; Stewart, Murray; Duke, Thomas (2010) Simulation of cell motility that reproduces the force-velocity relationship. Proc Natl Acad Sci U S A 107:9141-6
Yi, Kexi; Wang, Xu; Emmett, Mark R et al. (2009) Dephosphorylation of major sperm protein (MSP) fiber protein 3 by protein phosphatase 2A during cell body retraction in the MSP-based amoeboid motility of Ascaris sperm. Mol Biol Cell 20:3200-8
Miao, Long; Vanderlinde, Orion; Liu, Jun et al. (2008) The role of filament-packing dynamics in powering amoeboid cell motility. Proc Natl Acad Sci U S A 105:5390-5
Yi, Kexi; Buttery, Shawnna M; Stewart, Murray et al. (2007) A Ser/Thr kinase required for membrane-associated assembly of the major sperm protein motility apparatus in the amoeboid sperm of Ascaris. Mol Biol Cell 18:1816-25
Rodriguez, Maria Antonia; LeClaire 3rd, Lawrence L; Roberts, Thomas M (2005) Preparing to move: assembly of the MSP amoeboid motility apparatus during spermiogenesis in Ascaris. Cell Motil Cytoskeleton 60:191-9
Grant, Richard P; Buttery, Shawnna M; Ekman, Gail C et al. (2005) Structure of MFP2 and its function in enhancing MSP polymerization in Ascaris sperm amoeboid motility. J Mol Biol 347:583-95
Wolgemuth, Charles W; Miao, Long; Vanderlinde, Orion et al. (2005) MSP dynamics drives nematode sperm locomotion. Biophys J 88:2462-71
Buttery, Shawnna M; Ekman, Gail C; Seavy, Margaret et al. (2003) Dissection of the Ascaris sperm motility machinery identifies key proteins involved in major sperm protein-based amoeboid locomotion. Mol Biol Cell 14:5082-8

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