Nongenomic Signaling Mechanisms of Environmental Estrogens

描述（由申请人提供）：内分泌干扰化学品（如环境雌激素）污染我们的环境，损害动物（可能包括人类）的生殖健康。这些化合物可能作为不适当的雌激素，和/或干扰内源性雌激素的作用，但其在低环境相关浓度下的作用机制在很大程度上是未知的。我们最近表明，信号级联导致诱导功能启动雌二醇（E2）在质膜上也有力地启动非生理性雌激素（异源雌激素）。在表达膜形式的雌激素受体-a（mER a）的细胞中，每种异种雌激素通过激活细胞外调节激酶（ERK）和/或钙升高引起独特的信号传导模式（时间，剂量反应）。我们现在将讨论（1）通过比较具有不同碳链长度和结构的烷基酚异源雌激素和显著的生理雌激素的作用，激活mER α以产生信号的结构要求及其相关功能。（2）活性烷基酚通过加和、协同和拮抗机制与生理雌激素联合作用的能力;（3）这些反应的G蛋白偶联。G蛋白可能位于我们以前的工作和其他人的信号反应的上游。我们现在将通过免疫共沉淀、使用特异性抑制剂、显性阴性G蛋白亚型和诱饵相互作用肽方法来寻找G蛋白亚型与mERa相互作用的直接证据。将检查G蛋白偶联对生理雌激素和烷基酚异源雌激素的响应变化。我们的长期目标是使用我们建立的模型系统来回答各种详细的机制问题，即不同生理雌激素和异种雌激素亚类的特定结构特征如何通过非基因组途径和mER α影响作用，从而破坏内分泌过程。健康相关性：了解环境雌激素如何破坏正常的信号传导和生殖功能，将有助于设计新的预防和治疗策略来应对其毒性。证明它们的低剂量效应也将指导重新评估联邦规定环境雌激素的法律的污染限度。环境雌激素导致雌激素过度分泌疾病的程度和机制（例如，乳腺癌和垂体癌、不孕症），以便将接触限制在安全水平。

DESCRIPTION (provided by applicant): Endocrine-disrupting chemicals such as environmental estrogens contaminate our surroundings and impair the reproductive health of animals, and probably humans. These compounds may act as inappropriate estrogens, and/or interfere with the actions of endogenous estrogens, but their mechanisms of action at low, environmentally relevant concentrations are largely unknown. We have recently shown that signal cascades leading to induced functions initiated by estradiol (E2) at the plasma membrane are also potently initiated by nonphysiological estrogens (xenoestrogens). In cells that express a membrane form of the estrogen receptor-a (mERa), each xenoestrogen elicited unique signaling patterns (temporal, dose-response) via activation of extracellular-regulated kinases (ERKs) and/or calcium elevation. We will now address (1) the structural requirements for activating mERa to generate signals and their linked functions, by comparing the effects of alkylphenol xenoestrogens having varying carbon- chain lengths and structures, and prominent physiological estrogens (E2, estriol, and estrone); (2) active alkylphenols' ability of to act in combination with physiological estrogens via additive, synergistic, and antagonistic mechanisms; and (3) the G protein coupling of these responses. G proteins likely lie upstream of the signaling responses shown by our previous work and others'. We will now seek direct evidence for G protein subtype interactions with mERa via co-immunoprecipitation, use of specific inhibitors, and dominant-negative G protein subtype and decoy interaction peptide approaches. Changes in G protein coupling in response to both physiological estrogens and alkylphenol xenoestrogens will be examined. Our long-term objective is to use our established model system to answer a variety of detailed mechanistic questions about how specific structural features of different physiological estrogens and xenoestrogen subclasses affect actions through the nongenomic pathway and the mERa, and thereby disrupt endocrine processes. Health relevance: Knowing how environmental estrogens disrupt normal signaling and reproductive functions will enable design of new prevention and treatment strategies to deal with their toxicity. Demonstrating their low-dose effects will also guide re-evaluation of Federal regulations setting legal contamination limits for environmental estrogens. The extent and mechanisms by which environmental estrogens contribute to diseases of estrogen overexposure (eg. breast and pituitary cancers, infertility) must be understood so that exposures can be limited to safe levels.