Nongenomic Signaling by Steroids at the Cell Membrane

描述(由申请人提供)：一个长期存在的类固醇问题 生理学是类固醇如何调节非基因组或转录无关的， 效果。快速、类固醇触发的非基因组信号的例子有无数， 包括雌激素介导的一氧化氮合酶(NOS)上调 骨肉瘤内皮细胞，维生素D诱导的钙动员 细胞，黄体酮诱导青蛙和鱼卵母细胞成熟。这些 信号事件可能调节重要的生物功能，如血液 血管松弛、骨代谢和受精。不幸的是，大多数 这些过程是复杂生物系统的一部分，很难 在体外进行操作，这在试图理解 它们背后的生物学。这项建议使用了类固醇诱导的现象 蛙卵母细胞成熟作为非基因组研究的实验模型 类固醇信号。卵母细胞的成熟是指在 卵母细胞休眠的地方。“未成熟”卵母细胞在减数分裂前期受阻 I期，而成熟卵母细胞处于中期II期。类固醇诱导这种重新进入 通过转录独立的过程进入细胞周期，该过程似乎 涉及膜结合的经典类固醇受体，可能通过G 蛋白质。尽管存在争议，但卵母细胞的主要生理介体 非洲爪哇的成熟似乎是雄激素--睾酮。这个系统 在研究类固醇的非基因组信号方面提供了许多优势。 类固醇诱导的卵母细胞成熟是可重复的，很容易检测到，并且 在生物学上相关。此外，卵母细胞在体外很容易被操纵以 蛋白质表达和信号转导研究。这项建议的目的是：1) 提高对类固醇诱导的早期信号通路的认识 卵母细胞，包括G蛋白在成熟过程中的作用；以及2) 阐明经典雄激素受体在成熟发育中的作用 进程。理解非基因组类固醇诱导的卵母细胞信号转导 证明有助于阐明其他非基因组所涉及的机制 信号通路，并可能导致对控制其 相关的生物过程。

DESCRIPTION (provided by applicant): A longstanding question in steroid physiology is how steroids mediate nongenomic, or transcription-independent, effects. Examples of rapid, steroid-triggered nongenomic signaling are myriad, including estrogen-mediated up-regulation of nitric oxide synthase (NOS) in endothelial cells, vitamin D-induced calcium mobilization in osteosarcoma cells, and progesterone-induced maturation of frog and fish oocytes. These signaling events may mediate important biological functions such as blood vessel relaxation, bone metabolism, and fertilization. Unfortunately, most of these processes are part of complex biological systems that are difficult to manipulate in vitro, which presents a serious problem when trying to understand the biology behind them. This proposal uses the phenomenon of steroid-induced maturation of frog oocytes as an experimental model for studying nongenomic steroid signaling. The maturation of an oocyte refers to the meiotic stage at which an oocyte rests. "Immature" oocytes are arrested in prophase of meiosis I, while "mature" oocytes rest in metaphase II. Steroids induce this re-entry into the cell cycle via a transcription-independent process that appears to involve membrane bound classical steroid receptors and possibly signaling via G proteins. Although controversial, the primary physiological mediator of oocyte maturation in Xenopus appears to be the androgen, testosterone. This system offers many advantages in studying nongenomic signaling by steroids. Steroid-induced oocyte maturation is reproducible, easy to detect, and biologically relevant. Furthermore, oocytes are easily manipulated in vitro for protein expression and signaling studies. The aims of this proposal are: 1) to improve our knowledge of the early signaling pathways induced by steroids in oocytes, including the role of G proteins, in the maturation process; and 2) to elucidate the role of the classical androgen receptor in the maturation process. Understanding nongenomic steroid-induced signaling in oocytes should prove helpful in elucidating the mechanisms involved in other nongenomic signaling pathways and may lead to new insights toward controlling their associated biological processes.