"Mixtures of Xenoestrogens Alter Estradiol-induced Non-Genomic Signaling"

描述(申请人提供)：内分泌干扰物(EDCs)，如异种雌激素(XE)，已被证明通过新的细胞信号机制模拟或拮抗生理雌激素的影响，增加生殖和发育异常的可能性。我们实验室以前在垂体细胞上的研究表明，这些类固醇化合物通过激活非基因组信号通路[如丝裂原激活蛋白激酶(MAPKs)、G蛋白、钙离子]而有效而快速地发挥作用，导致特定细胞功能终点(细胞增殖、细胞凋亡和多肽分泌等分化功能)的改变。烷基酚(AP；NP)和结构上相关的双酚A(BPA)是已知的XE，已在人体血清和尿液中检测到大量的XE(NM范围)。单独的AP激活细胞外调节的激酶(ERK)，并在低浓度下以明显的非单调浓度依赖性有效地干扰生理雌激素信号转导。然而，这些XE并不是以单独化合物的形式存在于环境中，而是以混合物的形式存在。很少有研究考察雌激素(E2)对改变非基因组信号通路和功能反应的组合效应。这项研究的总体假设是，BPA和AP等XE的混合物可以通过膜雌激素受体(Mer)亚型在垂体细胞系(GH3/B6/F10)中引起复合的不适当信号调节。为了验证这一假说，提出了以下具体目标：目的一：确定XE和生理雌激素E2对信号通路的联合作用；目的二：确定XE混合物启动非基因组信号通路的膜结合雌激素受体(MER)亚型；目的三：研究联合XE暴露对细胞功能反应破坏的信号通路效应之间的相关性。

DESCRIPTION (provided by applicant): Endocrine disrupting chemicals (EDCs), such as xenoestrogens (XEs), have been shown to mimic or antagonize the effects of physiological estrogens via novel cellular signaling mechanisms, increasing the likelihood of reproductive and developmental abnormalities. Previous studies from our lab in pituitary cells demonstrated that these steroid-mimicking compounds potently and rapidly exert their effects via activation of non-genomic signaling pathways [e.g. mitogen-activated protein kinases (MAPKs), G proteins, Ca2+] leading to alterations of specific cellular functional endpoints (cell proliferation, apoptoss and differentiated functions such as secretion of peptides). Alkylphenols (APs; nonylphenol (NP) and the structurally related bisphenol-A (BPA)) are known XEs that have been detected in significant amounts in human serum and urine (nM range). Individual APs activate extracellular-regulated kinases (ERKs) as well as potently disrupt physiologic estrogen signaling at low, environmentally relevant concentrations with pronounced non-monotonic concentration- dependence. These XEs, however, do not exist in an environmental setting as individual compounds, but rather as mixtures. Few studies have examined the combinatorial effects to alter non-genomic signaling pathways and functional responses induced by estradiol (E2). The overall hypothesis underlying this study is that mixtures of XEs such as BPA and APs can cause compounded inappropriate regulation of signaling via membrane estrogen receptor (mER) subtypes in a pituitary cell line (GH3/B6/F10). To test this hypothesis the following Specific Aims are proposed: Aim I: Determine the combined effect of XEs with the physiologic estrogen E2, on signaling pathways; Aim II: Identify the membrane-bound estrogen receptor (mER) subtype by which XE mixtures initiate non-genomic signaling pathways; AIM III: Examine correlations between the signaling pathway effects of combined XE exposure to disruption of cellular functional responses.