Retinoic acid receptor-α up-regulates proopiomelanocortin gene expression in AtT20 corticotroph cells

Endocrine Journal

Takeo Yoshikawa⁴  Hiroyuki Kagechika²  Rehana Parvin⁶  Akiko Saito-Hakoda⁶  Kyoko Shimizu⁶  Akira Sugawara⁶  Akira Uruno³  Ikuko Sato⁶  Atsushi Yokoyama⁶  Masataka Kudo¹  Ken Matsuda¹  Naotaka Kogure⁶  Yasumasa Iwasaki⁵  Sadayoshi Ito¹ 

[1] Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan;Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo 101-0062, Japan;Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan;Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan;Health Service Center, Kochi University, Kochi 780-8520, Japan;Department of Molecular Endocrinology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan

关键词: RARα;    Pomc;    ACTH;   

DOI  :  10.1507/endocrj.EJ14-0115

学科分类：内分泌与代谢学

来源: Japan Endocrine Society

【 摘 要 】

References(37)Cited-By(1)Cushing’s disease is a disorder caused by excessive ACTH secretion from a corticotroph tumor of the pituitary gland.Although its standard therapy is a transsphenoidal surgery, innovation of novel medical treatments for the disease is urgently necessary.Retinoic acid (RA) has been reported to suppress adrenocorticotropic hormone (ACTH) secretion in Cushing’s disease.However, the role of RA receptor (RAR) in proopiomelanocortin (Pomc) gene expression remains uncertain.We here examined the involvement of RARα in Pomc regulation using AtT20 corticotroph cells.Surprisingly, a synthetic RARα agonist Am80 increased Pomc mRNA expression, CRH-induced ACTH secretion, and Pomc promoter activity.Small interfering RNA-mediated RARα-knockdown suppressed both basal and Am80-induced Pomc promoter activity.RARα-overexpression dose-dependently increased Pomc promoter activity.Pomc promoter mutation analysis revealed that both Tpit and NeuroD1 binding elements were responsible for the Am80-mediated effect.Am80 increased Tpit expression while RAR antagonist LE540 suppressed the increase.Tpit-overexpression increased Pomc promoter activity.Mammalian two-hybrid assay revealed that Am80 induced NeuroD1-RARα interaction.NeuroD1-overexpression enhanced the Am80-induced Pomc promoter activity, which was suppressed by NeuroD1 truncated mutant-overexpression.RARα thus positively regulates ACTH secretion/Pomc gene expression through interaction with NeuroD1 and Tpit expression increase.The present observation will be useful for the future development of the RA/retinoid-derived therapeutics of the disease.

【 授权许可】

Unknown