Regulation of aldosterone production from zona glomerulosa cells by ANG II and cAMP: evidence for PKA-independent activation of CaMK by cAMP.
Aldosterone production in zona glomerulosa (ZG) cells of adrenal glands is regulated by various extracellular stimuli (K(+), ANG II, ACTH) that all converge on two major intracellular signaling pathways: an increase in cAMP production and calcium (Ca(2+)) mobilization. However, molecular events downstream of the increase in intracellular cAMP and Ca(2+) content are controversial and far from being completely resolved. Here, we found that Ca(2+)/calmodulin-dependent protein kinases (CaMKs) play a predominant role in the regulation of aldosterone production stimulated by ANG II, ACTH, and cAMP. The specific CaMK inhibitor KN93 strongly reduced ANG II-, ACTH-, and cAMP-stimulated aldosterone production. In in vitro kinase assays and intact cells, we could show that cAMP-induced activation of CaMK, using the adenylate cyclase activator forskolin or the cAMP-analog Sp-5,6-DCI-cBIMPS (cBIMPS), was not mediated by PKA. Activation of the recently identified cAMP target protein Epac (exchange protein directly activated by cAMP) by 8-pCPT-2'-O-Me-cAMP had no effect on CaMK activity and aldosterone production. Furthermore, we provide evidence that cAMP effects in ZG cells do not involve Ca(2+) or MAPK signaling. Our results suggest that ZG cells, in addition to PKA and Epac/Rap proteins, contain other as yet unidentified cAMP mediator(s) involved in regulating CaMK activity and aldosterone secretion.
Gambaryan
Stepan
S
Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Wurzburg, Germany. gambaryan@klin-biochem.uni-wuerzburg.de
Butt
Elke
E
Tas
Piet
P
Smolenski
Albert
A
Allolio
Bruno
B
Walter
Ulrich
U
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000450:Aldosterone / Q000096:biosynthesis*; D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002417:Cattle; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004004:Dichlororibofuranosylbenzimidazole / Q000031:analogs & derivatives / Q000494:pharmacology; D004347:Drug Interactions; D004789:Enzyme Activation; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D013449:Sulfonamides / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D015384:Zona Glomerulosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000096926:Benzenesulfonamides
D000324:Adrenocorticotropic Hormone; D000450:Aldosterone; D000804:Angiotensin II; D001596:Benzylamines; D002118:Calcium; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D004004:Dichlororibofuranosylbenzimidazole; D020662:Guanine Nucleotide Exchange Factors; D020559:Monomeric GTP-Binding Proteins; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D013873:Thionucleotides; C482601:Epac protein, mouse; C071644:5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3',5'-monophosphorothioate; C072105:KN 93; D000096926:Benzenesulfonamides