Inducible cAMP Early Repressor in ovarian function.

描述（由申请人提供）：细胞周期蛋白D2的正常表达对fsh介导的卵巢颗粒细胞增殖至关重要。细胞周期蛋白d2缺失的雌性小鼠由于颗粒细胞的生长受损而不育。在正常小鼠中，FSH诱导颗粒细胞中细胞周期蛋白D2的表达，而LH抑制细胞周期蛋白D2的表达。阐明细胞周期蛋白D2表达的调控途径将增强我们对颗粒细胞正常发育的理解。我们和其他人发现，诱导性cAMP早期抑制因子（ICER）在颗粒细胞中可被LH诱导表达。我们证明，在培养的初始颗粒细胞中，ICER抑制了细胞周期蛋白D2启动子的活性。研究表明，ICER通过存在于周期蛋白D2启动子中的cAMP应答元件（CRE）介导这种抑制。此外，初始颗粒细胞中ICER的异位表达完全抑制pka诱导的DNA合成。这些数据表明，ICER通过控制细胞周期蛋白D2的表达参与卵巢颗粒细胞的正常发育。为了验证这一假设，我们建议使用可诱导和颗粒特异性的ICER转基因小鼠。提出以下具体目标：1)小鼠模型的生化验证；可诱导的卵巢特异性ICER转基因；2)测定FSH诱导ICER对颗粒细胞的生理影响；3)确定ICER在体内是否调控cyclin D2的表达。本课题的目标是完成这些小鼠的表征，并获得必要的初步数据，将这些小鼠作为模型系统来研究ICER对卵巢发育的调节。本提案中生成的数据将构成未来R01申请的基础。

DESCRIPTION (provided by applicant): Normal expression of cyclin D2 is crucial for FSH-mediated ovarian granulosa cell proliferation. Cyclin D2-null female mice are sterile because the growth of the granulosa cells is impaired. In the normal mouse, FSH induces whereas LH inhibits cyclin D2 expression in granulosa cells. The elucidation of the regulatory pathways governing the expression of cyclin D2 will enhance our understanding of the normal development of granulosa cells. Others and we have found that Inducible cAMP Early Repressor (ICER) expression is induced by LH in granulosa cells. We demonstrated that in cultured naive granulosa cells, ICER repressed the activity of the cyclin D2 promoter. ICER was shown to mediate this repression through a putative cAMP response element (CRE) present in the cyclin D2 promoter. Moreover, ectopic expression of ICER in naive granulosa cells completely inhibits PKA-induced DNA synthesis. These data suggest that ICER is involved in the normal development of ovarian granulosa cells by controlling cyclin D2 expression. In order to test this hypothesis we propose to use inducible and granulosa-specific ICER transgenic mice. The following specific aims are proposed: 1) Biochemical validation of the mouse model; an inducible ovarian specific transgenic of ICER; 2) To determine the physiological effects of ICER induction by FSH on granulosa cells; 3) To determine whether ICER regulates cyclin D2 expression in vivo. The goal of this proposal is to complete the characterization of these mice and to obtain the necessary preliminary data to use these mice as a model system to study ICER regulation of ovarian development. The data generated in this proposal will form the basis for a future R01 application.