Nuclear Receptor 5A (NR5A) Family Regulates 5-Aminolevulinic Acid Synthase 1 (ALAS1) Gene Expression in Steroidogenic Cells

作者：Ju Yunfeng; Mizutani Tetsuya^*; Imamichi Yoshitaka; Yazawa Takashi; Matsumura Takehiro; Kawabe Shinya; Kanno Masafumi; Umezawa Akihiro; Kangawa Kenji; Miyamoto Kaoru

来源：Endocrinology, 2012, 153(11): 5522-5534.

DOI：10.1210/en.2012-1334

5-Aminolevulinic acid synthase 1 (ALAS1) is a rate-limiting enzyme for heme biosynthesis in mammals. Heme is essential for the catalytic activities of P450 enzymes including steroid metabolic enzymes. Nuclear receptor 5A (NR5A) family proteins, steroidogenic factor-1 (SF-1), and liver receptor homolog-1 (LRH-1) play pivotal roles in regulation of steroidogenic enzymes. Recently, we showed that expression of SF-1/LRH-1 induces differentiation of mesenchymal stem cells into steroidogenic cells. In this study, genome-wide analysis revealed that ALAS1 was a novel SF-1-target gene in differentiated mesenchymal stem cells. Chromatin immunoprecipitation and reporter assays revealed that SF-1/LRH-1 up-regulated ALAS1 gene transcription in steroidogenic cells via binding to a 3.5-kb upstream region of ALAS1. The ALAS1 gene was up-regulated by overexpression of SF-1/LRH-1 in steroidogenic cells and down-regulated by knockdown of SF-1 in these cells. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha, a coactivator of nuclear receptors, also strongly coactivated expression of NR5A-target genes. Reporter analysis revealed that peroxisome proliferator-activated receptor-gamma coactivator-1 alpha strongly augmented ALAS1 gene transcription caused by SF-1 binding to the 3.5-kb upstream region. Finally knockdown of ALAS1 resulted in reduced progesterone production by steroidogenic cells. These results indicate that ALAS1 is a novel NR5A-target gene and participates in steroid hormone production. (Endocrinology 153: 5522-5534, 2012)

• 出版日期2012-11