OSTEOBLAST COMMITMENT AND DIFFERENTIATION BY ANGELS

天使对成骨细胞的承诺和差异化

• 批准号: 6861687
• 负责人: STAVROS C. MANOLAGAS
• 金额: $ 24.99万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6861687
• 关键词: biological signal transduction; bone morphogenetic proteins; cell differentiation; cell growth regulation; cell line; cell proliferation; estrogen receptors; laboratory mouse; osteoblasts; protein localization; receptor expression; sex hormones

DESCRIPTION (provided by applicant): 4-Estren-3alpha,17beta-diol (estren), a synthetic ligand of the estrogen (ER) or androgen (AR) receptor represents a novel class of activators of nongenotropic estrogen-like signaling (ANGELS), compounds that faithfully reproduce the nongenotropic actions of estradiol on osteoblast and osteoclast apoptosis in vitro and in vivo but lack the genotropic effects of classical estrogen. Estren has been shown to have distinct biologic effects compared to estradiol. Unlike estradiol, estren has no effect on female or male reproductive organs but increases serum osteocalcin, cortical width, and bone mineral density of ovariectomized females above the level of the estrogen-replete controls. In view of estren's distinct skeletal profile, versus classical estrogen or other anti-remodeling agents, the postulate that the superior effects of estren must result not only from its favorable effect on bone cell apoptosis, but also from additional mechanisms, will be tested. In studies leading directly to this application, the hypothesis that, unlike estradiol, estren may promote the commitment and/or differentiation of osteoblast progenitors, was explored. Estren induced lineage commitment and differentiation toward osteoblasts via ER-/AR-dependent, kinase-mediated potentiation of BMP-2 and Wnt signaling. Estradiol and DHT are three to four orders of magnitude less potent than estren in these effects. Unlike purported pro-differentiating effects of estradiol, which could be only shown in cells in which the expression of ERalpha was artificially increased by transfection of an ERalpha cDNA, the pro-differentiating effects of estren are demonstrable in bone cells, which express low levels of endogenous ER and AR. Thus, the molecular mechanism of the induction of osteoblast lineage commitment and differentiation by estren will be elucidated by (1) determining the specificity of the ligand/receptor interaction and (2) the involvement of BMP and Wnt signaling in these effects in murine and human osteoblast progenitors and in bone in vivo. A mechanistic explanation will also be sought for why sex steroids, although capable of nongenotropic signaling, differ from estren in their ability to induce lineage commitment and promote osteoblast differentiation, by (3) searching for genotropic counter-regulatory actions on cytokines, kinases, and the BMP and Wnt and signaling pathways. Results of these studies could provide essential understanding for mechanisms to control bone anabolism.

描述（由申请人提供）：4-Estren-3α,17β-二醇（estren），雌激素（ER）或雄激素（AR）受体的合成配体，代表一类新型非促基因雌激素样信号传导激活剂（ANGELS），该化合物忠实地再现雌二醇对成骨细胞和破骨细胞的非促基因作用 体外和体内细胞凋亡，但缺乏经典雌激素的基因调节作用。与雌二醇相比，雌激素已被证明具有独特的生物效应。与雌二醇不同，雌激素对女性或男性生殖器官没有影响，但会增加卵巢切除女性的血清骨钙素、皮质宽度和骨矿物质密度，使其高于雌激素充足的对照水平。鉴于雌激素与经典雌激素或其他抗重塑剂相比具有独特的骨骼特征，将测试以下假设：雌激素的卓越效果不仅来自其对骨细胞凋亡的有利作用，而且还来自其他机制。在直接导致该应用的研究中，探索了这样的假设：与雌二醇不同，雌激素可以促进成骨细胞祖细胞的定型和/或分化。雌激素通过 ER-/AR 依赖性、激酶介导的 BMP-2 和 Wnt 信号传导增强，诱导向成骨细胞的谱系定型和分化。雌二醇和双氢睾酮的这些作用比雌激素低三到四个数量级。雌二醇的促分化作用只能在通过转染 ERα cDNA 人为增加 ERα 表达的细胞中显示，而雌二醇的促分化作用则不同，雌二醇的促分化作用在表达低水平内源 ER 和 AR 的骨细胞中是明显的。因此，雌激素诱导成骨细胞谱系定型和分化的分子机制将通过（1）确定配体/受体相互作用的特异性和（2）BMP和Wnt信号传导参与小鼠和人类成骨细胞祖细胞和体内骨的这些效应来阐明。还将通过(3)寻找对细胞因子、激酶、BMP和Wnt以及信号通路的基因向反调节作用，来寻求机制解释，解释为什么性类固醇虽然能够产生非基因型信号传导，但在诱导谱系定型和促进成骨细胞分化的能力方面与雌激素不同。这些研究的结果可以为控制骨合成代谢的机制提供重要的理解。