title: 8-Phenylthio-adenines stimulate the expression of steroid hydroxylases, Cav3.2 Ca²⁺ channels, and cortisol synthesis by a cAMP-independent mechanism.
abstract: The regulation of cortisol synthesis and the expression of genes coding for steroidogenic proteins by 8-substituted cAMP and 8-substituted adenine derivatives were studied in bovine adrenal zona fasciculata (AZF) cells. At concentrations of 10-50 μM, 8-(4-chlorophenylthio)-cAMP (8CPT-cAMP), but not the poorly hydrolyzable Sp-8CPT-cAMP, stimulated large increases in cortisol synthesis and CYP17 mRNA expression. Of the three Epac (exchange protein activated by cAMP)-specific cAMP analogs, 8CPT-2'-OMe-cAMP, but not 8HPT-2'-OMe-cAMP or 8MeOPT-2'-OMe-cAMP, induced mRNAs for CYP17 and CYP11a1 steroid hydroxylases and stimulated cortisol synthesis. 8-Substituted adenine derivatives (10-200 μM), including 8PT-adenine, 8MeOPT-adenine, and 8CPT-adenine, stimulated similar large, concentration-dependent, and reversible increases in cortisol synthesis and steroid hydroxylase gene expression, whereas 8Br-adenine was ineffective. The phenylthio-adenine derivatives produced additive effects on cortisol synthesis when applied to AZF cells in combination with 8Br-cAMP. In contrast, no additivity was observed for these three compounds when used in combination with ACTH. 8PT-adenine did not activate PKA or inhibit DNA synthesis by AZF cells. 8PT-adenine-stimulated cortisol secretion and CYP17 steroid hydroxylase mRNA expression were potently inhibited by diphenyl-butylpiperidine T-type Ca(2+) antagonists. In AZF cells, 8PT-adenine and 8MeOPT-adenine induced the expression of both CACNA1H mRNA and associated Ca(v)3.2 Ca(2+) current. These results indicate that 8-chloro (but not 8-hydroxy- or 8-methoxy-)-phenylthio-cAMP analogs are converted to an active metabolite, 8CPT-adenine, that induces the expression of genes coding for steroidogenic proteins in bovine AZF cells. Other PT-adenine analogs also potently stimulate cortisol synthesis through the same unidentified signaling pathway that requires the expression of functional Ca(v)3.2 Ca(2+) channels. These phenylthio-adenine compounds and ACTH may stimulate cortisol synthesis through the same cAMP-independent mechanism.
authors.affiliation: Department of Neuroscience, The Ohio State University College of Medicine and Public Health, Columbus, Ohio 43210-1269, USA.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Enyeart
authors.forename: Haiyan
authors.initials: H
authors.lastname: Liu
authors.forename: John J
authors.initials: JJ
authors.lastname: Enyeart
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D000225:Adenine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D020747:Calcium Channels, T-Type / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D004353:Drug Evaluation, Preclinical; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006854:Hydrocortisone / Q000096:biosynthesis* / Q000378:metabolism; D008954:Models, Biological; D015398:Signal Transduction / Q000187:drug effects; D013250:Steroid Hydroxylases / Q000235:genetics* / Q000378:metabolism; D013873:Thionucleotides / Q000737:chemistry / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D020747:Calcium Channels, T-Type; D013873:Thionucleotides; D015124:8-Bromo Cyclic Adenosine Monophosphate; C016957:adenosine-3',5'-cyclic phosphorothioate; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; C044258:8-chloro-cyclic adenosine monophosphate; D000242:Cyclic AMP; D013250:Steroid Hydroxylases; D000225:Adenine; D006854:Hydrocortisone