The role of calcium/phospholipid-dependent protein kinase in Leydig cell steroidogenesis.
Purified rat Leydig cell cytosol was found to contain a protein kinase which was dependent on the presence of both calcium and phospholipids (phosphatidylserine and diolein), i.e. calcium/phospholipid-dependent protein kinase. The peak of Ca/phospholipid-dependent protein kinase was separated from type I and type II cAMP-dependent protein kinase by DE-52 chromatography. 4 beta-Phorbol-12-myristate-13-acetate (PMA), a tumor-promoting agent, could substitute for diolein in activation of Ca/phospholipid-dependent protein kinase. PMA caused dose-dependent increments of testosterone formation by Leydig cells, whereas inactive phorbol esters had no significant effects. PMA-induced testosterone formation was dependent on extracellular calcium and could be blocked by the addition of the calcium channel-blocking agent nifedipine. Since PMA can directly activate Ca/phospholipid-dependent protein kinase and increase testosterone formation, these results suggest that Ca/phospholipid-dependent protein kinase may be involved in modulating Leydig cell steroidogenesis in addition to the classical cAMP-dependent protein kinase pathway.
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D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007985:Leydig Cells / Q000378:metabolism*; D008297:Male; D010718:Phosphatidylserines / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology*; D011494:Protein Kinases / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000096:biosynthesis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D006063:Chorionic Gonadotropin; D004075:Diglycerides; D010718:Phosphatidylserines; D010743:Phospholipids; D015124:8-Bromo Cyclic Adenosine Monophosphate; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D000242:Cyclic AMP; D011494:Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C013965:diolein