ESTROGEN RECEPTOR SIGNALING PATHWAYS IN BONE

骨骼是雌激素(E)作用的主要靶点之一，因为E调节骨骼的生长和重塑。 尽管E水平降低被认为是骨质疏松的主要原因之一，但特定的分子 E调节骨代谢的途径尚未完全确定或了解。本项目 使用新的小鼠和细胞模型的组合来在细胞和分子水平上定义 E调节骨转换和骨量的信号通路，主要集中在以下两种方式： 雌激素受体-α(Era)的功能：经典的作用模式，era直接与 DMA上的雌激素反应元件(ERE)，以及ERA间接发挥作用的非经典模式 通过蛋白质-蛋白质与其他转录因子的相互作用。初步数据显示，老鼠 包含消除经典ERA信号的ERA突变(NERKI)表现为骨量减少和受损 男性皮质骨和松质骨均有骨形成，但女性仅在皮质骨形成。我们 假设由于雌性小鼠体内E水平的增加，ER(3)的作用是减轻 骨小梁中的NERKI受体。在目标1中，我们通过评估再培训局的损失来直接测试这一点 导致雌性NERKI小鼠出现更大的骨骼缺陷，但雄性NERKI小鼠不会。我们将检查野生型的骨骼， NERKI//ERB/和NERKI//ERB-/-小鼠使用骨密度测量和组织形态计量学。AIM 2测试了这一点 通过评估这些小鼠的骨髓基质细胞的能力在细胞水平上的假说 沿着成骨细胞谱系定位和分化。使用定量聚合酶链式反应分析， 我们将测试NERKI受体的表达导致WNTS和WNTS反应受损的假设 BMPS，而ERP调节这些效应。目标3研究经典Era信令在 染色质免疫沉淀法在非经典DNA结合部位募集NERKI受体 化验。最后，Aim 4使用一种新的转基因方法来检查选择性的骨骼后果 仅在成骨细胞中用NERKI受体取代内源性Era。总的来说，这些研究 将提供对骨骼中ER信号通路的更详细的了解。

The skeleton is one of the main targets of estrogen (E) action, as E regulates bone growth and remodeling. Although decreased E levels are known to be one of the main causes of osteoporosis, the specific molecular pathways by which E regulates bone metabolism are not fully characterized or understood. This Project uses a combination of novel mouse and cell models to define, at the cellular and molecular level, the signaling pathways by which E regulates bone turnover and bone mass, focusing on two modalities by which the estrogen receptor-alpha (ERa) functions: the classical mode of action, where ERa directly interacts with estrogen response elements (EREs) on DMA, and the non-classical mode, where ERa indirectly functions through protein-protein interactions with other transcription factors. Preliminary data demonstrates that mice containing an ERa mutation that eliminates classical ERa signaling (NERKI) exhibit osteopenia and impaired bone formation in both cortical and trabecular bone in males, but only in cortical bone in females. We hypothesize that due to increased E levels in female mice, ER(3 functions to mitigate the negative effects of the NERKI receptor in trabecular bone. In Aim 1, we directly test this by assessing whether loss of ERB leads to greater skeletal deficits in female, but not male NERKI mice. We will examine bones from wild type, NERKI//ERB+/+, and NERKI//ERB-/- mice using bone densitometry and histomorphometry. Aim 2 tests this hypothesis at the cellular level by assessing the ability of bone marrow stromal cells from these mice to commit and differentiate along the osteoblast lineage. Using quantitative polymerase chain reaction assays, we will test the hypotheses that expression of the NERKI receptor leads to impaired responses to Wnts and BMPs, and that ERP modulates these effects. Aim 3 examines loss of classical ERa signaling on the recruitment of the NERKI receptor to non-classical DNA binding sites using chromatin immunoprecipitation assays. Finally, Aim 4 uses a novel transgenic approach to examine the skeletal consequences of selective replacement of the endogenous ERa with the NERKI receptor only in osteoblasts. Collectively, these studies will provide a more detailed understanding of ER signaling pathways in bone.