GATA4 reduction enhances 3',5'-cyclic adenosine 5'-monophosphate-stimulated steroidogenic acute regulatory protein messenger ribonucleic acid and progesterone production in luteinized porcine granulosa cells.
GATA4 reduction enhances 3',5'-cyclic adenosine 5'-monophosphate-stimulated steroidogenic acute regulatory protein messenger ribonucleic acid and progesterone production in luteinized porcine granulosa cells.
复制标题
DOI：
10.1210/en.2008-0484
复制
发表时间：
2008-11
期刊：
影响因子：
4.8
通讯作者：
Yvonne Hui;H. LaVoie
中科院分区：
文献类型：
--
作者：
Yvonne Hui;H. LaVoie
以前对培养的颗粒细胞的研究表明，GATA4参与了促性腺激素对类固醇生成急性调节蛋白(STAR)基因的调节。对这些先前研究的警告是存在的。首先，当GATA6表达相对较高时，黄体颗粒细胞中的GATA4水平在黄体生成素高峰后降低。其次，STAR mRNA在颗粒细胞中的表达可以忽略不计，直到黄体生成素高峰之后。外源GATA4和GATA6均能反式激活STAR基因启动子。我们使用RNA干扰(RNAi)方法来确定GATA4和GATA6在黄体形成颗粒细胞内源性STAR基因的cAMP类似调控中的作用。在对照RNAi条件下用cAMP刺激STAR基因的表达。令人惊讶的是，通过各自的RNAi减少GATA4，STAR mRNA的cAMP诱导几乎翻了一番。在cAMP处理24小时时，这种增强作用被GATA4+GATA6共同下调所消除。GATA6的下调本身并不改变STAR的mRNA水平。GATA4+GATA6共同下调可使基础细胞色素P11A基因表达水平升高，但不影响cAMP对其诱导作用。GATA4 RNAi条件下HSD3B基因的基础水平降低，cAMP对HSD3B基因的诱导倍数增加。GATA4下调可促进倍体cAMP刺激的孕酮生成，但GATA4+GATA6共同下调不能促进孕酮的产生。这些数据表明，GATA6在cAMP刺激的STAR mRNA和GATA4减少条件下孕酮的下游积累中起促进作用。数据还表明，GATA4/6的基础水平不是诱导STAR基因cAMP所必需的。排卵后GATA4/GATA6比例的改变可能使GATA6增强STAR基因的积累。
Previous studies with cultured granulosa cells implicated GATA4 in gonadotropin regulation of the steroidogenic acute regulatory protein (STAR) gene. Caveats to these prior studies exist. First, GATA4 levels are reduced in granulosa-luteal cells after the LH surge when GATA6 expression is relatively high. Second, STAR mRNA expression is negligible in granulosa cells until after the LH surge. Both exogenous GATA4 and GATA6 can transactivate STAR gene promoter constructs. We used an RNA interference (RNAi) approach to determine the contributions of GATA4 and GATA6 to cAMP analog regulation of the endogenous STAR gene in luteinizing granulosa cells. STAR mRNA was stimulated by cAMP under control RNAi conditions. Surprisingly, GATA4 reduction by its respective RNAi approximately doubled the cAMP induction of STAR mRNA. At 24 h cAMP treatment, this augmentation was abolished by co-down-regulation of GATA4+GATA6. GATA6 down-regulation by itself did not alter STAR mRNA levels. GATA4+GATA6 co-down-regulation elevated basal CYP11A mRNA at 24 h treatment but did not affect its induction by cAMP. Basal levels of HSD3B mRNA were reduced by GATA4 RNAi conditions leading to a greater fold induction of its mRNA by cAMP. Fold cAMP-stimulated progesterone production was enhanced by GATA4 down-regulation but not by GATA4+GATA6 co-down-regulation. These data implicate GATA6 as the facilitator in cAMP-stimulated STAR mRNA and downstream progesterone accumulation under reduced GATA4 conditions. Data also demonstrate that basal levels of GATA4/6 are not required for cAMP induction of the STAR gene. The altered ratio of GATA4 to GATA6 after ovulation may allow GATA6 to enhance STAR mRNA accumulation.