Nongenomic Signaling Mechanisms of Environmental Estrogens

环境雌激素等扰乱内分泌的化学物质污染我们的周围环境，损害 动物的生殖健康，可能还有人类。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，但其作用机制较低，与环境有关 浓度在很大程度上是未知的。我们最近证明了信号级联导致诱导函数 由雌二醇(E_2)在质膜上启动也可由非生理性雌激素有效启动 (异种雌激素)。在表达膜状雌激素受体-a(MERA)的细胞中，每种异种雌激素 通过激活细胞外调节激酶(ERK)诱导独特的信号模式(时间、剂量-反应) 和/或钙升高。我们现在将讨论(1)激活MERA以生成 信号及其关联功能，通过比较具有不同碳元素的烷基酚外源雌激素的影响。 链的长度和结构，以及显著的生理雌激素(雌三醇和雌酮)；(2)活性 烷基酚与生理雌激素通过相加作用、协同作用和 拮抗机制；(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工作显示了信号响应。我们现在将寻找G蛋白亚型的直接证据 通过免疫共沉淀、使用特异性抑制剂和显性阴性G蛋白亚型与MERA相互作用 和诱饵相互作用肽接近。两种生理雌激素对G蛋白偶联反应的变化 和烷基苯酚异种雌激素将被检测。我们的长期目标是利用我们已建立的模式系统 回答各种详细的机械问题，关于不同生理功能的具体结构特征 雌激素和异种雌激素亚类通过非基因组途径和mera影响作用，从而 扰乱内分泌过程。与健康相关：了解环境雌激素如何扰乱正常信号和 生殖功能将使设计新的预防和治疗战略来处理其毒性。 证明它们的低剂量效应也将指导重新评估设定合法污染的联邦法规 环境雌激素限量。环境雌激素对环境的影响程度和机制 必须了解雌激素过度暴露的疾病(如乳腺癌和垂体癌、不孕症)，以便暴露于 可以被限制在安全水平。

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 membraneform 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.