The orphan nuclear receptors NURR1 and NGFI-B modulate aromatase gene expression in ovarian granulosa cells: A possible mechanism for repression of aromatase expression upon luteinizing hormone surge
The orphan nuclear receptors NURR1 and NGFI-B modulate aromatase gene expression in ovarian granulosa cells: A possible mechanism for repression of aromatase expression upon luteinizing hormone surge
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DOI：
10.1210/en.2004-0889
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发表时间：
2005-01-01
期刊：
影响因子：
4.8
通讯作者：
Hu, YF
中科院分区：
文献类型：
--
作者：
Wu, YM;Ghosh, S;Hu, YF
卵巢颗粒细胞在卵巢功能的许多方面起着关键作用，包括卵泡发生和类固醇发生。在FSH和LH的作用下，颗粒细胞内cAMP水平升高导致多个卵巢基因被激活。在这里，我们报告了人类颗粒样肿瘤细胞系KGN中camp响应基因表达谱的全基因组研究结果。该研究确定了140个基因在受到腺苷酸环化酶激活剂forskolin的刺激后被2倍或更大的激活或抑制。通过实时荧光定量PCR进一步分析部分camp应答基因的诱导模式。与先前的观察结果一致，lh应答基因，如核受体4A亚家族（NURR1， NGFI-B和NOR-1），被快速但短暂地诱导，而编码芳香化酶的fsh应答基因CYP19则以延迟的方式诱导。有趣的是，NURR1或NGFI-B的异位表达严重减弱了卵巢特异性芳香化酶启动子的camp响应激活。通过小干扰RNA减少内源性NURR1或NGFI-B可显著提高芳香酶基因的表达。负责NURR1/ ngfi - b介导的抑制的顺式元件被映射到赋予camp响应性的最小芳香化酶启动子序列。此外，NURR1的dna结合域是抑制所必需的。综上所述，这些结果强烈提示芳香化酶mRNA的快速下降与核受体亚家族4A表达的诱导之间存在因果关系，这种关系伴随着卵巢卵泡发育后期LH激增而发生。
Ovarian granulosa cells play pivotal roles in many aspects of ovary functions including folliculogenesis and steroidogenesis. In response to FSH and LH, the elevation of intracellular cAMP level in granulosa cells leads to activation of multiple ovarian genes. Here, we report findings from a genome-wide study of the cAMP-responsive gene expression profiles in a human granulosa-like tumor cell line, KGN. The study identified 140 genes that are either activated or repressed by 2-fold or greater after stimulation by the adenylyl cyclase activator forskolin. The induction patterns of some cAMP-responsive genes were further analyzed by quantitative real-time PCR. Consistent with previous observations, the LH-responsive genes, such as the nuclear receptor 4A subfamily (NURR1, NGFI-B, and NOR-1), were rapidly but transiently induced, whereas the FSH-responsive gene CYP19 encoding aromatase was induced in a delayed fashion. Interestingly, ectopic expression of NURR1 or NGFI-B severely attenuated the cAMP-responsive activation of the ovary-specific aromatase promoter. Reduction of the endogenous NURR1 or NGFI-B by small interfering RNA significantly elevated aromatase gene expression. The cis-elements responsible for NURR1/NGFI-B-mediated repression were mapped to the minimal aromatase promoter sequence that confers camp responsiveness. Furthermore, the DNA-binding domain of NURR1 was required for the repression. Taken together, these results strongly suggest a causal relationship between the rapid decline of aromatase mRNA and induction of nuclear receptor subfamily 4A expression, which concomitantly occur upon LH surge at the later stages of ovarian follicular development.