Nongenomic Steroid Signaling in Oocytes

描述（由申请人提供）：经典类固醇受体在体外介导许多转录非依赖性（非基因组）类固醇反应。该领域的一个主要问题是证明这些非基因组过程的生物学意义，因为解剖基因组与非基因组类固醇受体介导的信号传导的相对重要性是困难的。为了避免这些问题，我们的实验室研究类固醇诱导成熟，或减数分裂恢复，卵母细胞。卵母细胞成熟是一个重要的，生物学相关的，类固醇介导的现象，是公认的发生完全独立于转录。事实上，在卵母细胞成熟过程中，转录是沉默的，许多类固醇诱导的细胞质信号实际上发生在去核的青蛙卵母细胞中。这个应用程序是我们的R 01的竞争性更新，“类固醇在细胞膜的非基因组信号。“对于第一笔赠款，我们提议研究非洲爪蟾卵母细胞中类固醇触发的减数分裂。在过去的4年中，我们：1）发现雄激素是非洲爪蟾卵母细胞成熟的生理介质; 2）暗示经典雄激素受体（AR）是雄激素触发成熟的介质; 3）描述了一种“抑制释放”机制，即类固醇减弱了维持细胞减数分裂停滞的组成性G蛋白信号; 4）表明类固醇受体的非基因组作用的调节剂（MNAR）将AR连接到G β; 5）开始对参与维持减数分裂停滞的爪蟾GPRS进行表征; 6）证明桩蛋白在调节类固醇触发的信号中的作用;和7）显示非基因组类固醇介导的信号传导从青蛙到小鼠是保守的。这个竞争性更新的目的，“卵母细胞中的非基因组类固醇信号传导”，是建立在我们从以前的资助期的结果。我们将：1）使用小鼠敲除模型来检查经典类固醇受体在调节类固醇触发的卵母细胞成熟中的重要性; 2）表征MNAR作为卵母细胞成熟的调节剂和作为G蛋白信号传导的一般调节剂的作用;和3）阐明桩蛋白在调节卵母细胞成熟和MAPK信号传导两者中的作用。这些研究将在类固醇受体和G蛋白介导的信号传导、MAPK信号传导和蛋白质翻译以及减数分裂和卵巢功能等领域做出重大贡献。

DESCRIPTION (provided by applicant): Classical steroid receptors mediate many transcription-independent (nongenomic) steroid responses in vitro. A major problem in this field has been to justify the biological significance of these nongenomic processes, since dissecting the relative importance of genomic versus nongenomic steroid receptor- mediated signaling is difficult. To circumvent these concerns, our laboratory studies steroid-induced maturation, or meiotic resumption, of oocytes. Oocyte maturation is an important, biologically relevant, steroid-mediated phenomenon that is well-accepted to occur completely independent of transcription. In fact, transcription is silenced during oocyte maturation, and many steroid-induced cytoplasmic signals actually occur in enucleated frog oocytes. This application is a competitive renewal for our R01, "Nongenomic Signaling by Steroids at the Cell Membrane." For the first grant we proposed to study steroid-triggered meiosis in Xenopus laevis oocytes. In the past 4 years, we: 1) showed that androgens are the physiologic mediators of Xenopus oocyte maturation; 2) implicated classical androgen receptors (ARs) as mediators of androgen-triggered maturation; 3) described a "release of inhibition" mechanism whereby steroids attenuate constitutive G protein signaling that holds cells in meiotic arrest; 4) showed that the Modulator of Nongenomic Actions of steroid Receptors (MNAR) links the AR to Gbeta; 5) began characterization of Xenopus GPRS, which participates in maintaining meiotic arrest; 6) demonstrated a role for Paxillin in regulating steroid-triggered signals; and 7) showed that nongenomic steroid-mediated signaling is conserved from frogs to mice. The aims of this competitive renewal, "Nongenomic Steroid Signaling in Oocytes," are to build upon our results from the previous funding period. We will: 1) use mouse knockout models to examine the importance of classical steroid receptors in regulating steroid-triggered oocyte maturation; 2) characterize the role of MNAR as a regulator of oocyte maturation and as a general modulator of G protein signaling; and 3) elucidate the role of Paxillin in regulating both oocyte maturation and MAPK signaling. These studies should lead to significant contributions in the fields of steroid receptor and G protein-mediated signaling, MAPK signaling and protein translation, as well as in the fields of meiosis and ovarian function.