Yazawa Takashi, Inaoka Yoshihiko, Okada Reiko, Mizutani Tetsuya, Yamazaki Yukiko, Usami Yoko, Kuribayashi Mayu, Orisaka Makoto, Umezawa Akihiro, Miyamoto Kaoru
Department of Biochemistry, Faculty of Medical Sciences, University of Fukui, Shimoaizuki 23-3, Matsuoka, Eiheiji-cho, Fukui 910-1193, Japan.
Mol Endocrinol. 2010 Mar;24(3):485-96. doi: 10.1210/me.2009-0352. Epub 2010 Feb 4.
Previously, we demonstrated that bone marrow-derived mesenchymal stem cells (MSCs) differentiate into steroidogenic cells such as Leydig and adrenocortical cells by the introduction of steroidogenic factor-1 (SF-1) and treatment with cAMP. In this study, we employed the same approach to differentiate umbilical cord blood (UCB)-derived MSCs. Despite UCB-MSCs differentiating into steroidogenic cells, they exhibited characteristics of granulosa-luteal-like cells. We found that peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) was expressed and further induced by cAMP stimulation in UCB-MSCs. Consistent with these results, tissue-specific expression of Pgc-1alpha was observed in rat ovarian granulosa cells. PGC-1alpha binds to the NR5A family [SF-1 and liver receptor homolog-1 (LRH-1)] of proteins and markedly enhances their transcriptional activities. Reporter assays revealed that PGC-1alpha activated the promoter activities of SF-1 and LRH-1 target genes. Infection of KGN cells (a human cell line derived from granulosa cells) with adenoviruses expressing PGC-1alpha resulted in the induction of steroidogenesis-related genes and stimulation of progesterone production. PGC-1alpha also induced SF-1 and LRH-1, with the latter induced to a greater extent. Knockdown of Pgc-1alpha in cultured rat granulosa cells resulted in attenuation of gene expression as well as progesterone production. Transactivation of the NR5A family by PGC-1alpha was repressed by Dax-1. PGC-1alpha binds to the activation function 2 domain of NR5A proteins via its consensus LXXLL motif. These results indicate that PGC-1alpha is involved in progesterone production in ovarian granulosa cells by potentiating transcriptional activities of the NR5A family proteins.
此前，我们证明了骨髓间充质干细胞（MSCs）通过导入类固醇生成因子-1（SF-1）并经环磷酸腺苷（cAMP）处理后可分化为类固醇生成细胞，如睾丸间质细胞和肾上腺皮质细胞。在本研究中，我们采用相同方法诱导脐带血（UCB）来源的MSCs分化。尽管UCB-MSCs分化为类固醇生成细胞，但它们表现出类颗粒黄体细胞的特征。我们发现，过氧化物酶体增殖物激活受体γ共激活因子-1α（PGC-1α）在UCB-MSCs中表达，并在cAMP刺激下进一步诱导表达。与这些结果一致，在大鼠卵巢颗粒细胞中观察到Pgc-1α的组织特异性表达。PGC-1α与NR5A家族蛋白[SF-1和肝脏受体同源物-1（LRH-1）]结合，并显著增强其转录活性。报告基因检测显示，PGC-1α激活了SF-1和LRH-1靶基因的启动子活性。用表达PGC-1α的腺病毒感染KGN细胞（一种源自颗粒细胞的人细胞系）导致类固醇生成相关基因的诱导和孕酮生成的刺激。PGC-1α还诱导了SF-1和LRH-1，其中后者诱导程度更大。在培养的大鼠颗粒细胞中敲低Pgc-1α导致基因表达以及孕酮生成减弱。Dax-1抑制了PGC-1α对NR5A家族的反式激活作用。PGC-1α通过其共有LXXLL基序与NR5A蛋白的激活功能2结构域结合。这些结果表明，PGC-1α通过增强NR5A家族蛋白的转录活性参与卵巢颗粒细胞中孕酮的生成。
