Although many of the effects of luteinizing hormone (LH) in the corpus luteum are thought to be mediated by cAMP, the exact mechanism of action of LH is unknown. It is presumed that the LH-induced events in ovarian tissues mediated by cAMP occur via cAMP-dependent protein kinases. Phosphorylation of proteins is one of the major post-translational mechanisms by which cellular functions are regulated. We have recently described another important messenger system in ovarian tissues which is linked to protein phosphorylation. Receptor-mediated increases in second messengers derived from phosphoinositide metabolism (diacylglycerol and inositol phosphates) lead to the activation of a calcium- and phospholipid-dependent protein kinase (C-kinase). The regulation of phosphoinositide metabolism by LH and other hormones and the presence of C-kinase in the corpus luteum suggest that the control of C-kinase activity is related to the function of the corpus luteum.
The specific aims of the proposed research are to purify and further characterize this new protein kinase and evaluate its physiological significance in rat and bovine corpora lutea. The enzyme will be purified with the objectives of 1) determining the specific co-factors required for C-kinase activity, 2) producing monoclonal antibodies to C-kinase for the purpose of detection and quantitation of C-kinase, and 3) determining the substrate specificity of C-kinase. The physiological role for C-kinase will be examined by 1) determining whether or not enzyme activity varies throughout the life span of the corpus luteum and 2) determining if enzyme activity is regulated by LH or other factors known to regulate luteal function. The possible involvement of C-kinase in the regulation of luteal function will be determined by examining its role in 1) gonadotropin binding, 2) receptor phosphorylation, 3) adenylate cyclase activation, and 4) progesterone synthesis. These studies will be carried out by monitoring the phosphorylation of both exogenous and endogenous substrate proteins. The proposed studies on the ovarian C-kinase may provide new insight into the mechanism of LH action and establish a link between hormonally-induced changes in C-kinase activation and corpus luteum function.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
7R01HD022248-04
Application #
3321737
Study Section
Biochemical Endocrinology Study Section (BCE)
Project Start
1986-08-01
Project End
1990-09-30
Budget Start
1988-09-30
Budget End
1990-09-30
Support Year
4
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Kansas
Department
Type
Schools of Medicine
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
May, J V; Stephenson, L A; Turzcynski, C J et al. (1996) Transforming growth factor beta expression in the porcine ovary: evidence that theca cells are the major secretory source during antral follicle development. Biol Reprod 54:485-96
Keel, B A; Hildebrandt, J M; May, J V et al. (1995) Effects of epidermal growth factor on the tyrosine phosphorylation of mitogen-activated protein kinases in monolayer cultures of porcine granulosa cells. Endocrinology 136:1197-204
Chakravorty, A; Joslyn, M I; Davis, J S (1993) Characterization of insulin and insulin-like growth factor-I actions in the bovine luteal cell: regulation of receptor tyrosine kinase activity, phosphatidylinositol-3-kinase, and deoxyribonucleic acid synthesis. Endocrinology 133:1331-40
Gangrade, B K; Gotcher, E D; Davis, J S et al. (1993) The secretion of transforming growth factor-beta by bovine luteal cells in vitro. Mol Cell Endocrinol 93:117-23
Davis, J S (1992) Modulation of luteinizing hormone-stimulated inositol phosphate accumulation by phorbol esters in bovine luteal cells. Endocrinology 131:749-57
Duncan, R A; Davis, J S (1991) Prostaglandin F2 alpha stimulates inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate formation in bovine luteal cells. Endocrinology 128:1519-26
Alila, H W; Davis, J S; Dowd, J P et al. (1990) Differential effects of calcium on progesterone production in small and large bovine luteal cells. J Steroid Biochem 36:687-93
Ganguly, A; Chiou, S; West, L A et al. (1989) Atrial natriuretic factor inhibits angiotensin-induced aldosterone secretion: not through cGMP or interference with phospholipase C. Biochem Biophys Res Commun 159:148-54
Davis, J S; Tedesco, T A; West, L A et al. (1989) Effects of human chorionic gonadotropin, prostaglandin F2 alpha and protein kinase C activators on the cyclic AMP and inositol phosphate second messenger systems in cultured human granulosa-luteal cells. Mol Cell Endocrinol 65:187-93
Davis, J S; Alila, H W; West, L A et al. (1989) Second messenger systems and progesterone secretion in the small cells of the bovine corpus luteum: effects of gonadotropins and prostaglandin F2a. J Steroid Biochem 32:643-9

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