Mutual effects of melatonin and activin on induction of aldosterone production by human adrenocortical cells

• Published in: The Journal of steroid biochemistry and molecular biology Vol. 152; pp. 8 - 15
• Main Authors: Hara, Takayuki, Otsuka, Fumio, Tsukamoto-Yamauchi, Naoko, Inagaki, Kenichi, Hosoya, Takeshi, Nakamura, Eri, Terasaka, Tomohiro, Komatsubara, Motoshi, Makino, Hirofumi
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2015
• Subjects: Activin; Activin Receptors, Type I - biosynthesis; Activins - pharmacology; Adrenal Cortex - cytology; Adrenal Cortex - metabolism; Adrenocorticotropic Hormone - metabolism; Adrenocorticotropic Hormone - pharmacology; Adrenocorticotropin; Aldosterone; Aldosterone - biosynthesis; Angiotensin II - metabolism; Cell Line, Tumor; Cytochrome P-450 CYP11B2 - genetics; Humans; Hydrocortisone - biosynthesis; Melatonin; Melatonin - pharmacology; Phosphorylation; Receptor, Melatonin, MT1 - biosynthesis; Receptor, Melatonin, MT1 - genetics; RNA, Messenger - biosynthesis; Smad2 Protein - metabolism; Smad6 Protein - biosynthesis; Smad7 Protein - biosynthesis; Steroid 17-alpha-Hydroxylase - genetics; Steroidogenesis; ALK; Melatonin; BMP; MR; IBMX; MT; PKA; ACTH; AT1R; ActRI; MAPK; Aldosterone; Adrenocorticotropin; BMPRII; TGF; ActRII; CYP11B2; ACTH-R; CYP17; BMPRI; Steroidogenesis; Activin; AngII
• ISSN: 0960-0760; 1879-1220
• DOI: 10.1016/j.jsbmb.2015.04.012

•Melatonin increased aldosterone synthesis induced by ACTH and activin in adrenocortical cells.•Melatonin amplified cAMP synthesis and CYP11B2/CYP17 expression induced by ACTH and activin.•Melatonin enhanced activin-induced Smad2 signaling and activin upregulated MT1 expression.•Functional link of melatonin and activin was uncovered in ACTH-induced aldosterone output. Melatonin has been reported to suppress adrenocorticotropin (ACTH) secretion in the anterior pituitary and cortisol production in the adrenal by different mechanisms. However, the effect of melatonin on aldosterone production has remained unknown. In this study, we investigated the role of melatonin in the regulation of aldosterone production using human adrenocortical H295R cells by focusing on the activin system expressed in the adrenal. Melatonin receptor MT1 mRNA and protein were expressed in H295R cells and the expression levels of MT1 were increased by activin treatment. Activin increased ACTH-induced, but not angiotensin II (Ang II)-induced, aldosterone production. Melatonin alone did not affect basal synthesis of either aldosterone or cortisol. However, melatonin effectively enhanced aldosterone production induced by co-treatment with ACTH and activin, although melatonin had no effect on aldosterone production induced by Ang II in combination with activin. These changes in steroidogenesis became apparent when the steroid production was evaluated by the ratio of aldosterone/cortisol. Melatonin also enhanced dibutyryl-AMP-induced aldosterone/cortisol levels in the presence of activin, suggesting a functional link to the cAMP-PKA pathway for induction of aldosterone production by melatonin and activin. In accordance with the data for steroids, ACTH-induced, but not Ang II-induced, cAMP synthesis was also amplified by co-treatment with melatonin and activin. Furthermore, the ratio of ACTH-induced mRNA level of CYP11B2 compared with that of CYP17 was amplified in the condition of treatment with both melatonin and activin. In addition, melatonin increased expression of the activin type-I receptor ALK-4 but suppressed expression of inhibitory Smads6/7, leading to the enhancement of Smad2 phosphorylation. Collectively, the results showed that melatonin facilitated aldosterone production induced by ACTH and activin via the cAMP-PKA pathway. The results also suggested that mutual enhancement of melatonin and activin receptor signaling is involved in the induction of aldosterone output by adrenocortical cells.