This is a first time revised application intended to assess biochemical regulation of sperm motility. The long-term goal is to define the biochemical mechanisms underlying development and regulation of motility with emphasis on considerations of phosphorylation of proteins associated with the axoneme. Levels of phosphorylation are a balance between the action of protein kinases and protein phosphatases. The applicant has identified a sperm-specific protein phosphatase, PP1g2 that is involved in regulation of sperm motility. High activity of this enzyme results in low sperm motility, whereas vigorously motile sperm exhibit low enzyme activity. Specific inhibition of PP1g2 leads to initiation of motility in immotile sperm and to the stimulation of velocity and flagellar beat amplitude in motile sperm. Genetic and biochemical studies support the hypothesis of the applicant that PP1g2 is a key component regulating sperm phosphorylation and, hence, motility. The focus of this particular proposal is to study the biochemical mechanisms regulating PP1g2. The investigator hypothesizes that two sperm-specific regulatory proteins, P33 and P72, control the activity and the sub cellular localization of PP1g2. Furthermore, he believes that the interaction of PP1g2 with P33 is regulated by glycogen synthase kinase-3 phosphorylation.
Three Specific Aims to test these ideas are formulated as follows: (1) To purify and sequence the inhibitor P33 and to determine how it regulates PP1g2. (2) To determine the molecular basis for the sub cellular targeting of PP1g2 to the sperm flagellum and the anterior region of the sperm head. (3) To determine how PP1g2 and its activating enzyme glycogen synthase kinase-3 are regulated by sperm intracellular second messengers. Elucidation of such novel sperm biochemical mechanisms should lead to a better understanding of male gamete function, result in novel approaches for the regulation of sperm motility, and could enable better diagnosis and treatment of male factor infertility.
|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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