The long-term objective of the present proposal is to understand how progestins regulate the female reproductive axis, with particular emphasis on progesterone receptor (PR) gene regulation in ovarian granulosa cells. Progestins have been proposed to affect many aspects of ovarian function and to participate in the normal process of ovulation and/or luteinization of the follicle. We hypothesized that an intracellular PR molecule may mediate progesterone action in the ovary and therefore, isolated the rat PR cDNA and genomic clones to initiate a multifaceted approach to study the expression and regulation of ovarian PRs. Our preliminary results demonstrating transient PR gene expression in the granulosa cells of preovulatory follicles during the periovulatory period strongly suggest the potential involvement of PRs for mammalian ovulation. The regulatory mechanisms for PR gene expression in these cells appear to be quite different from other progesterone-responsive cells, because gonadotropins, but not estrogen, directly induce PR gene expression in rat granulosa cells. This gonadotropin-induced PR gene expression in ovarian granulosa cells is likely to be mediated by a cAMP- mediated pathway, at least in part, at the level of transcription. Our preliminary results also suggest the likely involvement of protein kinase C in PR gene regulation in ovarian granulosa cells. The central hypothesis in this proposal, then, is that the PR gene in ovarian granulosa cells is regulated predominantly by G protein-coupled signaling pathways, for example cAMP- and DAG-dependent pathways. We now propose to extend our preliminary studies to investigate the cellular and molecular mechanisms by which the PR gene is regulated in rat ovarian granulosa cells. The first goal of this proposal is to examine intracellular signaling pathways which are directly involved in PR gene expression in ovarian granulosa cells; - our studies will focus on protein kinases A and C. The second goal of this proposal is to identify and characterize the cis-DNA regulatory elements mediating the activation of the PR gene by these intracellular signaling pathways; our studies will focus on cAMP- or TPA-induced expression of the PR gene. The final goal of this proposal is to examine the potential role of estrogen in PR gene expression in rat granulosa cells; we will determine the capacity of ovarian granulosa cells in mediating estrogen-induced signals. We expect these experiments to enhance our understanding of PR regulation and function for the process of ovulation and/or luteinization in the mammalian ovary and to provide a framework for determining whether alterations in PR function might participate in reproductive diseases or dysfunction.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29HD030719-04
Application #
2403317
Study Section
Biochemical Endocrinology Study Section (BCE)
Project Start
1994-05-01
Project End
1999-04-30
Budget Start
1997-05-01
Budget End
1998-04-30
Support Year
4
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Kentucky
Department
Physiology
Type
Schools of Medicine
DUNS #
832127323
City
Lexington
State
KY
Country
United States
Zip Code
40506
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Ko, C; Park-Sarge, O K (2000) Progesterone receptor activation mediates LH-induced type-I pituitary adenylate cyclase activating polypeptide receptor (PAC(1)) gene expression in rat granulosa cells. Biochem Biophys Res Commun 277:270-9
Graham, K M; Ko, C; Park, K S et al. (2000) Expression of an intracisternal A-particle-like element in rat ovary. Biochem Biophys Res Commun 278:48-57
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Ko, C; In, Y H; Park-Sarge, O K (1999) Role of progesterone receptor activation in pituitary adenylate cyclase activating polypeptide gene expression in rat ovary. Endocrinology 140:5185-94
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Byers, M; Kuiper, G G; Gustafsson, J A et al. (1997) Estrogen receptor-beta mRNA expression in rat ovary: down-regulation by gonadotropins. Mol Endocrinol 11:172-82
Park-Sarge, O K; Parmer, T G; Gu, Y et al. (1995) Does the rat corpus luteum express the progesterone receptor gene? Endocrinology 136:1537-43
Park-Sarge, O K; Sarge, K D (1995) Cis-regulatory elements conferring cyclic 3',5'-adenosine monophosphate responsiveness of the progesterone receptor gene in transfected rat granulosa cells. Endocrinology 136:5430-7