A long-term goal of my laboratory is to understand the biochemical mechanisms underlying sperm motility and fertilization. In spermatozoa, where little protein synthesis occurs, protein phosphorylation is a major mechanism for regulating cellular functions. While it is known that changes in protein phosphorylation control motility initiation and fertilization, our knowledge of signaling pathways regulating these changes is limited. This proposal centers on a signaling enzyme in spermatozoa, the serine/threonine phosphatase PP1gamma2. It is a key enzyme in spermatogenesis and regulation of mature sperm function. Knowing how this enzyme works at the biochemical and molecular levels will contribute to our understanding of male gamete function. Protein purification and sequencing have enabled us to identify a number of potential PP1gamma2 binding and regulatory proteins. Immunoprecipitation and binding studies with recombinant proteins showed that two of these regulatory proteins are sds22 and protein 14-3-3 - discovered for the first time in spermatozoa. These polypeptides, which have critical functions in somatic cells, have novel roles in regulating male gamete function. In addition to changes in its binding to regulatory proteins, PP1gamma2 phosphorylation is increased during sperm maturation in the epididymis. The central hypothesis in this proposal is that the regulated action of PP1gamma2 is critical for sperm maturation, motility initiation, and other essential sperm functions. We will use biochemical and molecular approaches to characterize, at the mechanistic level, how phosphorylation and binding interactions between PP1gamma2 and its regulatory proteins relate to sperm motility and fertilizing ability. Aside from its basic importance to male gamete biology, this study has potential applications in the diagnosis and treatment of male infertility and in the development of novel approaches to male contraception.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD038520-06
Application #
7149180
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Rankin, Tracy L
Project Start
1999-12-01
Project End
2009-11-30
Budget Start
2006-12-01
Budget End
2007-11-30
Support Year
6
Fiscal Year
2007
Total Cost
$306,430
Indirect Cost
Name
Kent State University at Kent
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
041071101
City
Kent
State
OH
Country
United States
Zip Code
44242
Sinha, Nilam; Puri, Pawan; Nairn, Angus C et al. (2013) Selective ablation of Ppp1cc gene in testicular germ cells causes oligo-teratozoospermia and infertility in mice. Biol Reprod 89:128
Fiedler, Sarah E; Dudiki, Tejasvi; Vijayaraghavan, Srinivasan et al. (2013) Loss of R2D2 proteins ROPN1 and ROPN1L causes defects in murine sperm motility, phosphorylation, and fibrous sheath integrity. Biol Reprod 88:41
Sinha, Nilam; Pilder, Stephen; Vijayaraghavan, Srinivasan (2012) Significant expression levels of transgenic PPP1CC2 in testis and sperm are required to overcome the male infertility phenotype of Ppp1cc null mice. PLoS One 7:e47623
Soler, David C; Kadunganattil, Suraj; Ramdas, Shandilya et al. (2009) Expression of transgenic PPP1CC2 in the testis of Ppp1cc-null mice rescues spermatid viability and spermiation but does not restore normal sperm tail ultrastructure, sperm motility, or fertility. Biol Reprod 81:343-52
Chakrabarti, Rumela; Shepardson, Sally; Karmakar, Moumita et al. (2009) Extra-mitochondrial localization and likely reproductive function of a female-transmitted cytochrome c oxidase subunit II protein. Dev Growth Differ 51:511-9
Cheng, Lina; Pilder, Stephen; Nairn, Angus C et al. (2009) PP1gamma2 and PPP1R11 are parts of a multimeric complex in developing testicular germ cells in which their steady state levels are reciprocally related. PLoS One 4:e4861
Snow, Alan J; Puri, Pawan; Acker-Palmer, Amparo et al. (2008) Phosphorylation-dependent interaction of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein (YWHA) with PADI6 following oocyte maturation in mice. Biol Reprod 79:337-47
Puri, Pawan; Myers, Kimberley; Kline, Douglas et al. (2008) Proteomic analysis of bovine sperm YWHA binding partners identify proteins involved in signaling and metabolism. Biol Reprod 79:1183-91
Vijayaraghavan, Srinivasan; Chakrabarti, Rumela; Myers, Kimberley (2007) Regulation of sperm function by protein phosphatase PP1gamma2. Soc Reprod Fertil Suppl 63:111-21
Chakrabarti, R; Walker, J M; Chapman, E G et al. (2007) Reproductive function for a C-terminus extended, male-transmitted cytochrome c oxidase subunit II protein expressed in both spermatozoa and eggs. FEBS Lett 581:5213-9

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