title: Stimulation of testosterone production by atrial natriuretic peptide in isolated mouse Leydig cells results from a promiscuous activation of cyclic AMP-dependent protein kinase by cyclic GMP.
abstract: The aim of this study was to examine the possibility that atrial natriuretic peptide-stimulated testosterone production by mouse Leydig cells results from an activation of cAMP-dependent protein kinase (kinase A) by cGMP. In these cells, both 8Br-cGMP and 8Br-cAMP could stimulate testosterone production, though the latter was approximately 50-fold more potent. Following the stimulation of the cells with the atrial peptide, a dose-related decrease in the cellular protein-bound cAMP accompanied by a concomitant increase in the protein-bound cGMP was observed. The steroidogenesis stimulated by both human chorionic gonadotrophin (hCG) and atrial peptide was inhibited in a dose-dependent manner by a cAMP antagonist, adenosine 3',5'-cyclic monophosphothioate, Rp-isomer (RpcAMPS). In a cell-free [3H]cAMP binding assay, we have shown that unlabelled cGMP and RpcAMPS could competitively inhibit the [3H]cAMP binding, confirming that cAMP, RpcAMPS and cGMP could bind to the same binding protein. Finally, in a cell-free kinase A assay system, we have demonstrated that in lysates prepared from either atrial peptide or hCG-stimulated cells, the cellular kinase A was activated to an equal extent. We conclude from the data obtained that cGMP can bind to the cAMP-binding sites of kinase A and thereby brings about a promiscuous activation of this kinase. This appears to be an underlying mechanism by which atrial peptide hormone is able to stimulate the steroidogenesis in mouse Leydig cells.
authors.affiliation: Institute for Hormone and Fertility Research, UKE, University of Hamburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Schumacher
authors.forename: D
authors.initials: D
authors.lastname: Müller
authors.forename: A K
authors.initials: AK
authors.lastname: Mukhopadhyay
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002474:Cell-Free System; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D010446:Peptide Fragments / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism*; D015290:Second Messenger Systems / Q000187:drug effects*; D013739:Testosterone / Q000096:biosynthesis*; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D006063:Chorionic Gonadotropin; D010446:Peptide Fragments; D013873:Thionucleotides; D015124:8-Bromo Cyclic Adenosine Monophosphate; C016957:adenosine-3',5'-cyclic phosphorothioate; C016276:8-bromocyclic GMP; D013739:Testosterone; D009320:Atrial Natriuretic Factor; C062524:atrial natriuretic factor prohormone (103-125); D000242:Cyclic AMP; D011494:Protein Kinases; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine