Activation induced by luteinizing hormone of type II protein kinase dependent on cyclic adenosine monophosphate and phosphorylation of soluble proteins in porcine granulosa cells.
The present experiments were designed to study whether exogenous LH could elicit acute cyclic AMP-mediated activation of cyclic AMP-dependent protein kinase and phosphorylation of cellular protein in intact porcine granulosa cells. Incubation of porcine granulosa cells (from 3 to 5 mm diameter follicles) with 2 microgram luteinizing hormone/ml (LH) caused a significant rise of cellular cyclic AMP content within 2 min of the addition of LH. The increase was dose-dependent and occurred between doses of 0.2 and 2.0 microgram LH/ml. Luteinizing hormone also caused a time- and dose-dependent dissociation of the type II cyclic AMP-dependent protein kinase isozyme in porcine granulosa cells. Luteinizing hormone (0.05--2 microgram/ml) significantly dissociated the cyclic AMP-dependent protein kinase between 2 and 30 min after stimulation. The protein kinase dissociation was a specific effect of LH and was not elicited by either adrenocorticotrophic hormone or prolactin. During the period of LH-induced protein kinase activation, several soluble granulosa cell proteins, ranging in molecular weights from about 43 000 to 99 000, became phosphorylated in a time-dpeendent and hormone-specific manner. The results suggest that cyclic AMP-mediated activation of granulosa cell type II cyclic AMP-dependent protein kinase may be a prerequisite in the short-term molecular action of LH leading to LH-specific phosphorylation of several soluble granulosa cell proteins of an as yet unidentified function.
D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D010766:Phosphorylation; D011374:Progesterone / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D013268:Stimulation, Chemical; D013347:Subcellular Fractions / Q000378:metabolism; D013552:Swine
D011506:Proteins; D011374:Progesterone; D007986:Luteinizing Hormone; D000242:Cyclic AMP; D011494:Protein Kinases