The cAMP-dependent protein kinase (PKA) is targeted to specific subcellular compartments through its interaction with A kinase anchoring proteins (AKAPs). Membrane permeable peptides, designed to disrupt PKA/AKAP interaction, inhibit sperm motility, suggesting PKA anchoring is required for the maintenance of motility. The overall goal of this proposal is to characterize the interaction of sperm AKAPs with the type two regulatory subunit of PKA (RII) and RII-homologues, and determine how these interactions regulate spermatozoan function(s). We will focus on two sperm AKAPs. AKAP110 is a predominant sperm AKAP and the focus of our previous proposal. Radial Spoke Protein 3 (RSP3) is a newly discovered AKAP in Chlamydomonas. It is the first flagellar AKAP to be found in the axoneme. Mutation of this protein disrupts flagellar beating. We have recently identified, cloned and expressed the human homolog of this protein. Based on the location of this AKAP, we hypothesize that RSP3 regulates motility by coordinating the action of kinases and/or phosphatases in the axoneme. We have recently identified four sperm-specific human proteins, in addition to PKA, which interact with sperm AKAP110. All of these proteins have a strong sequence similarity to the AKAP docking and dimerization domains of RII. Although these sperm proteins appear to be functional homologues of RII in their ability to bind AKAPs, they do not share other functions of RII such as the ability to bind cAMP or the catalytic subunit of PKA. Two of these RII homologues appear to be part of the Rho signaling pathway. One is homologous to murine ropporin. Ropporin is found along the principal piece of the flagellum and binds to rhophilin, a target protein for Rho. A second protein, named AKAP-associated sperm protein (ASP), is 39 percent identical with ropporin. Agents that inhibit Rho signaling inhibit sperm motility. One goal of this proposal is to test the hypothesis that Rho signaling regulates sperm motility via a mechanism similar to that observed in smooth muscle and that sperm AKAPs coordinate this mechanism by acting as scaffolding molecules. Studies outlined in this proposal should facilitate the design of new and highly specific pharmacological reagents for inhibiting sperm function in vivo. Knowledge gained from these studies may also be useful for the diagnosis and treatment of patients with defects in sperm movement and fertility.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
2R01HD036408-04A1
Application #
6471553
Study Section
Reproductive Biology Study Section (REB)
Program Officer
Rankin, Tracy L
Project Start
1998-07-01
Project End
2007-04-30
Budget Start
2002-05-01
Budget End
2003-04-30
Support Year
4
Fiscal Year
2002
Total Cost
$271,800
Indirect Cost
Name
Oregon Health and Science University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009584210
City
Portland
State
OR
Country
United States
Zip Code
97239
Fiedler, Sarah E; Sisson, Joseph H; Wyatt, Todd A et al. (2012) Loss of ASP but not ROPN1 reduces mammalian ciliary motility. Cytoskeleton (Hoboken) 69:22-32
Newell, Amy E Hanlon; Fiedler, Sarah E; Ruan, Jenny M et al. (2008) Protein kinase A RII-like (R2D2) proteins exhibit differential localization and AKAP interaction. Cell Motil Cytoskeleton 65:539-52
Fiedler, Sarah E; Bajpai, Malini; Carr, Daniel W (2008) Identification and characterization of RHOA-interacting proteins in bovine spermatozoa. Biol Reprod 78:184-92
Bajpai, Malini; Fiedler, Sarah E; Huang, Zaohua et al. (2006) AKAP3 selectively binds PDE4A isoforms in bovine spermatozoa. Biol Reprod 74:109-18
Ayres, Allen W; Carr, Daniel W; McConnell, Daniel S et al. (2003) Expression and intracellular localization of protein phosphatases 2A and 2B, protein kinase a, A-Kinase anchoring protein (AKAP79), and binding of the regulatory (RII) subunit of protein kinase a to AKAP79 in human myometrium. J Soc Gynecol Investig 10:428-37
Kovo, M; Schillace, R V; Galiani, D et al. (2002) Expression and modification of PKA and AKAPs during meiosis in rat oocytes. Mol Cell Endocrinol 192:105-13
Carr, D W; Fujita, A; Stentz, C L et al. (2001) Identification of sperm-specific proteins that interact with A-kinase anchoring proteins in a manner similar to the type II regulatory subunit of PKA. J Biol Chem 276:17332-8
Niu, J; Vaiskunaite, R; Suzuki, N et al. (2001) Interaction of heterotrimeric G13 protein with an A-kinase-anchoring protein 110 (AKAP110) mediates cAMP-independent PKA activation. Curr Biol 11:1686-90
Salvador, L M; Park, Y; Cottom, J et al. (2001) Follicle-stimulating hormone stimulates protein kinase A-mediated histone H3 phosphorylation and acetylation leading to select gene activation in ovarian granulosa cells. J Biol Chem 276:40146-55
Vijayaraghavan, S; Mohan, J; Gray, H et al. (2000) A role for phosphorylation of glycogen synthase kinase-3alpha in bovine sperm motility regulation. Biol Reprod 62:1647-54

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