Proper rearrangement of the cell's microtubule cytoskeleton is an essential component of successful development. Important constituents of the cytoskeleton are its associated motor proteins which provide the force necessary for many microtubule-based movements. The long-term goal of this work is to understand how the activity of motor proteins is modulated during the complex changes in the cytoskeleton that occur during development. This proposal makes use of a small group of motor proteins related to the KIFC1 motor, in order to examine how relatively small changes in motor protein structure can alter function. KIFC1 isoforms differ in the domains responsible for cargo attachment and are found in several important microtubule complexes during mammalian spermatogenesis. The importance of the divergent cargo domains of KIFC1 isoforms to motor function will be investigated in the mitotic and meiotic spindles and the spermatid manchette. These microtuble-based structures perform very different functions during germ cell maturation but both contain KIFC1 isoforms suggesting a common function for these motors. The function of the spindles is well known: they and their associated motors act to segregate the genetic material during cell division. Less well characterized is the manchette that forms around the nucleus of elongating spermatids. Composed of about 1,000 microtubules, this structure is essential for the formation of viable sperm. The primary hypothesis to be tested in this study is that KIFC1 isoforms are targeted to different microtuble complexes where they act to stabilize these structures. Proposed experiments will identify the KIFC1 isoform composition of the spindle and manchette. The importance of the specific domains of these motors in directing these motors to the spindle and in microtuble bundling within the structure will be examined using in vivo and in vitro assays. Finally, the role of KIFC1 isoforms in the manchette will be examined by biochemical characterization and with in vitro motility assays. These studies will increase our understanding of how the interaction between motor and cargo is determined. Furthermore, the involvement of KIFC1 isoforms in multiple microtubule complexes during spermatogenesis has broad implications for regulation of the cytoskeleton in many other developmental systems. Given the involvement of KIFC1 homologs in the mitotic spindle, these motors are prime candidates for proper regulation of cell division and for misregulation during oncogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM060628-01
Application #
6041397
Study Section
Reproductive Biology Study Section (REB)
Program Officer
Deatherage, James F
Project Start
2000-02-01
Project End
2005-01-31
Budget Start
2000-02-01
Budget End
2001-01-31
Support Year
1
Fiscal Year
2000
Total Cost
$175,076
Indirect Cost
Name
East Carolina University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
City
Greenville
State
NC
Country
United States
Zip Code
27858
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Zhang, Yuguo; Wang, Rong; Jefferson, Holly et al. (2007) Identification of motor protein cargo by yeast 2-hybrid and affinity approaches. Methods Mol Biol 392:97-116
Nath, Sangeeta; Bananis, Eustratios; Sarkar, Souvik et al. (2007) Kif5B and Kifc1 interact and are required for motility and fission of early endocytic vesicles in mouse liver. Mol Biol Cell 18:1839-49
Yang, Wan-Xi; Jefferson, Holly; Sperry, Ann O (2006) The molecular motor KIFC1 associates with a complex containing nucleoporin NUP62 that is regulated during development and by the small GTPase RAN. Biol Reprod 74:684-90
Zhang, Yuguo; Sperry, Ann O (2004) Comparative analysis of two C-terminal kinesin motor proteins: KIFC1 and KIFC5A. Cell Motil Cytoskeleton 58:213-30
Yang, Wan-Xi; Sperry, Ann O (2003) C-terminal kinesin motor KIFC1 participates in acrosome biogenesis and vesicle transport. Biol Reprod 69:1719-29
Zou, Yong; Millette, Clarke F; Sperry, Ann O (2002) KRP3A and KRP3B: candidate motors in spermatid maturation in the seminiferous epithelium. Biol Reprod 66:843-55