Ovulation and luteinization are two processes that are induced in preovulatory follicles as a consequence of the LH surge. The overall goal of the studies proposed in this application is to determine some of the molecular mechanisms by which LH regulates these diverse processes; specifically to 1) determine the molecular mechanisms involved in LH-mediated induction of prostaglandin endoperoxide (PGH) synthase (PGS): transient induction; 2) determine the molecular mechanisms by which LH induces cholesterol size-chain cleavage P450 (P450scc): constitutive induction; Isolate and characterize luteal cell specific cDNA clones: ovarian tissue specific induction. The granulosa cell offers a unique systems for analyzing the molecular mechanisms of cAMP action because different genes appear to be turned on and turned off simultaneously within the same cell. Our hypothesis is the cAMP acts via cAMP-dependent protein kinases (primarily type II in granulosa cells and type I in luteinized cells) to phosphorylate specific trans-acting regulatory factors. These trans-acting factors are presumed to regulate the cAMP responsive domains in the 5' (or 3') flanking regions of the genes for PGS and cytochrome P450scc. Whether or not the same or different DNA or trans-acting factors are involved remains a key and central question to be addressed by the studies of this proposal. Therefore, our immediate goals are to obtain cDNA probes for PGS, cytochrome P450scc and other luteal cell specific proteins, to isolate 5' and 3' flanking regions of the genes for each of these proteins and ultimately to isolate the trans-acting factors that regulate their cAMP domains. By analyzing and comparing the 5' and 3' flanking regions of a gene that is transiently induced (PGS) by cAMP with one that appears to be constitutively turn on (P450scc) by cAMP, new insight into cAMP responsive DNA sequences and proteins regulating these domains in granulosa cells will be obtained. In addition, isolation of a PGS cDNA as well as a detailed analysis of the molecular events regulating the induction of PGS in granulosa cells should provide a broad base for understanding and regulating not only ovulation but also other inflammatory reactions. By identifying important regulatory domains and trans-acting factors important for LH- mediated luteinization new insight into this terminal stage of granulosa cell function and ways in which to modify it should be obtained.
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