Nongenomic Steroid Signaling in Oocytes

描述(申请人提供)：在体外，经典的类固醇受体介导许多转录非依赖(非基因组)的类固醇反应。这个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，因为剖析基因组和非基因组类固醇受体介导的信号传递的相对重要性是困难的。为了规避这些担忧，我们的实验室研究了类固醇诱导的卵母细胞成熟或减数分裂恢复。卵母细胞成熟是一种重要的、生物学上相关的类固醇调节现象，人们普遍认为它完全不依赖于转录。事实上，转录在卵母细胞成熟过程中是沉默的，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。这一应用是对我们的R01的竞争性更新，“类固醇在细胞膜上的非基因组信号。”在第一笔拨款中，我们提议研究类固醇触发的非洲爪哇卵母细胞减数分裂。在过去的4年中，我们：1)证明了雄激素是非洲爪哇卵母细胞成熟的生理介质；2)经典的雄激素受体(AR)被认为是雄激素触发的成熟的介质；3)描述了一种“释放抑制”的机制，通过该机制，类固醇可以减弱阻止细胞减数分裂的结构性G蛋白信号；4)类固醇受体的非基因组作用调节剂(MnAR)表明AR与Gbeta有关；5)非洲爪哇的GPR参与了维持减数分裂停止的特性；6)证明了PX在调节类固醇触发的信号中的作用；以及7)从青蛙到小鼠，表明了非基因组介导的类固醇信号是保守的。这一竞争性更新的目标是“卵母细胞中的非基因组类固醇信号”，目的是在我们上一次资助期间的结果的基础上再接再厉。我们将：1)使用小鼠基因敲除模型来研究经典的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)研究Mnar作为卵母细胞成熟调节因子和G蛋白信号转导的一般调节器的作用；3)阐明帕西林在调节卵母细胞成熟和MAPK信号转导中的作用。这些研究将在类固醇受体和G蛋白介导的信号转导、MAPK信号转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.