PDF(Pubmed)
Abstract：
Previous in vivo and in vitro studies have demonstrated a dramatic up-regulation of Krüppel-like factor 4 (Klf4) in rat preovulatory granulosa cells (GCs) after LH/hCG treatment and its role in regulating Cyp19A1 expression during the luteal shift in steroidogenesis. In this study, we examined whether Klf4 also mediates the LH-induced repression of Cyp17A1 expression in primary rat preovulatory GCs. In response to LH treatment of GCs in vitro, Cyp17A1 expression declined to less than half of its initial value by 1 h, remaining low for 24 h of culture. Overexpression of Klf4 decreased basal and Sf1-induced Cyp17A1 expressions and increased progesterone secretion. Reduction of endogenous Klf4 by siRNA elevated basal Cyp17A1 expression but did not affect LH-stimulated progesterone production. Overexpression of Klf4 also significantly attenuated Sf1-induced Cyp17A1 promoter activity. On the other hand, mutation of the conserved Sp1/Klf binding motif in the promoter revealed that this motif is not required for Klf4-mediated repression. Taken together, these data indicate that the Cyp17A1 gene may be one of the downstream targets of Klf4, which is induced by LH in preovulatory GCs. This information may help in identifying potential targets for preventing the molecular changes occurring in hyperandrogenic disorders.
摘要：
先前的体内和体外研究表明，LH/hCG治疗后，大鼠排卵前颗粒细胞（GC）中Krüppel样因子4（Klf4）的显着上调，及其在调节黄体移位期间Cyp19A1表达中的作用在类固醇生成中。在这项研究中,我们检测了Klf4是否也介导了LH诱导的原代大鼠排卵前GCs中Cyp17A1表达抑制。在体外对GC的LH治疗的反应中，Cyp17A1表达下降到不到其初始值的一半，1小时，培养24小时保持低位。Klf4的过表达降低了基础和Sf1诱导的Cyp17A1表达并增加了孕酮分泌。通过siRNA减少内源性Klf4升高基础Cyp17A1表达,但不影响LH刺激的孕酮产生。Klf4的过表达也显著减弱了Sf1诱导的Cyp17A1启动子活性。另一方面,启动子中保守的Sp1/Klf结合基序的突变表明，该基序不是Klf4介导的抑制所必需的。一起来看,这些数据表明Cyp17A1基因可能是排卵前GCs中LH诱导的Klf4的下游靶标之一。这些信息可能有助于确定预防高雄激素性疾病中发生的分子变化的潜在靶标。
