ERa Signaling Mechanisms Regulating Ovarian Function

卵巢雌激素在大脑、垂体和卵巢中发挥至关重要的体内平衡反馈作用，以 抑制雄激素的生物合成。这些反馈控制的中断总是会导致对 促性腺激素分泌，雄激素过多，以及生育能力受损。雌激素受体α(ERA)似乎 调解这些主要的负面反馈行动中的大多数。ERA信号转导机制包括“经典的遗传性” 由受体与DNA直接结合所介导的效应，“非经典遗传”效应包括 内质网与其他转录因子的连接以及由内质网介导的“非经典非遗传性”作用 连接到膜启动的信号通路。拟议的研究使用新的era突变小鼠来 进一步确定ERA介导E2反馈效应的细胞机制。我们利用了变种人 Era敲入小鼠，在没有Era的情况下，它提供非经典的遗传和非遗传的信号 经典信号，以确定非经典ERA信号传递E2负反馈作用 促黄体生成素分泌。目标1通过直接监测促性腺激素释放激素来确定这些反馈行为是否在大脑中明显 WT(era+/+)、era基因敲除(ER-/-)和非经典era对E2处理的分泌反应 基因“敲入”(ER-/AA)小鼠，以及神经元特异性ERA-/-小鼠。《目标2》考察了涉案情况 非经典遗传性与非遗传性Era在负反馈中的信号传递；E2发挥作用的能力 我们将比较这三种基因在控制GnRH释放的传入回路中的作用。目标3 分析卵泡膜细胞特异性era基因缺失突变小鼠的卵巢内反馈基因。然后我们评估 经典与非经典Era信号通过分析E2参与调节雄激素合成 对Era+/+、Era/-、Era-/AA小鼠培养卵泡的影响。在目标4中，我们确定了 哪些E2作用是由非经典的遗传性或膜启动的ERA信号介导的。新的 将产生只表达非经典膜启动信号的ERs的动物，或者 只有非经典的遗传信号。生殖轴中的雌二醇活动被挽救的程度 在这些老鼠身上将会被确定。这些实验将阐明ERA的基本机制 信号调节细胞和生理功能，并可能提供对 多囊卵巢综合征(PCOS)等内分泌疾病中高雄激素血症的发病机制。

Ovarian estrogens exert critically important homeostatic feedback actions in the brain, pituitary, and ovary to restrain androgen biosynthesis. Disruption of these feedback controls invariably leads to dysregulation of gonadotropin secretions, androgen excess, and impaired fertility. Estrogen receptor alpha (ERa) appears to mediate most of these major negative feedback actions. ERa signaling mechanisms include "classical genotropic" effects mediated by direct binding of receptors to DNA, "non-classical genotropic" effects involving tethering of ERs to other transcription factors, and "non-classical non-genotropic" actions mediated by ERs coupled to membrane-initiated signaling pathways. The proposed studies use novel ERa mutant mice to further determine cellular mechanisms by which ERa mediates E2 feedback effects. We have utilized mutant ERa knock-in mice, which confer non-classical genotropic and non-genotropic signaling in the absence of classical signaling, to determine that non-classical ERa signaling conveys E2 negative feedback actions on LH secretion. Aim 1 determines if these feedback actions are manifest in brain by directly monitoring GnRH secretory responses to E2 treatments in WT (ERa+/+), ERa gene knockout (ER-/-), and non-classical ERa gene "knock-in" (ER-/AA) mice, as well as in neuron-specific ERa-/- mice. Aim 2 examines the involvement of non-classical genotropic vs. non-genotropic ERa signaling in negative feedback; the ability of E2 to exert actions in afferent circuitries controlling GnRH release will be compared among the three genotypes. Aim 3 analyzes the locus of intraovarian feed-back in theca cell-specific ERa null mutant mice. We then assess involvement of classical vs. non-classical ERa signaling in regulating androgen synthesis by analyzing E2 effects in cultured ovarian follicles of ERa+/+, ERa/-., ERa-/AA mice. In Aim 4, we determine the extent to which E2 actions are mediated by non-classical genotropic vs. membrane-initiated ERa signaling. New animals will be generated that express ERs conferring non-classical membrane-initiated signaling only, or non-classical genotropic signaling only. The extent to which E2 actions in the reproductive axis are rescued in these mice will be determined. These experiments will clarify the basic mechanisms by which ERa signaling regulates cellular and physiological function, and may provide important insights into the pathogenesis of hyperandrogenism in endocrine disorders such as polycystic ovary syndrome (PCOS).