OSTEOBLAST COMMITMENT AND DIFFERENTIATION BY ANGELS

天使对成骨细胞的承诺和差异化

• 批准号: 7012312
• 负责人: STAVROS C. MANOLAGAS
• 金额: $ 24.4万
• 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 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7012312
• 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.

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体外和体内凋亡，但缺乏经典雌激素的基因因作用。与雌二醇相比，埃斯特伦已显示出具有不同的生物学作用。与雌二醇不同，埃斯特伦对雌性或雄性生殖器官没有影响，但会增加血清骨钙素，皮质宽度和卵巢切除的雌性的骨矿物质密度，而不是雌激素重生对照水平。鉴于埃斯特伦独特的骨骼轮廓，与经典的雌激素或其他抗塑料剂相比，假设埃斯特伦的出色作用不仅必须源于其对骨细胞凋亡的有利作用，而且还将源于其他机制。在直接实现这一应用的研究中，探索了埃斯坦可能促进成骨细胞祖细胞的承诺和/或分化的假设。埃斯特伦通过ER/AR依赖性，激酶介导的BMP-2和WNT信号传导的ER/AR依赖性，激酶介导的增强引起了对成骨细胞的谱系承诺和分化。在这些作用中，雌二醇和DHT的效力比埃克森少三到四个数量级。与所谓的雌二醇的促分化作用不同，雌二醇只能在细胞中显示，其中通过转染Eralpha cDNA，人为地增加了Eralpha的表达，酯的核细胞的前分化作用在骨细胞中可证明，而骨细胞表达低水平的内源性ER和AR水平。因此，通过（1）确定配体/受体相互作用的特异性以及（2）BMP和WNT信号在Murine和Human Osteemblast bone Inthevo中涉及BMP和WNT信号在这些作用中的参与，从而阐明了成骨细胞谱系承诺和分化成骨细胞谱系承诺和分化的分子机制。 （3）通过（3）搜索对细胞因子，激酶以及BMP和WNT和WNT和WNT和WNT和WNT的信号途径的遗传性相反，但还将寻求一种机械解释，以说明为什么性类固醇虽然能够进行非核信号传导，但与埃斯特伦的诱导谱系承诺和促进成骨细胞分化的能力有所不同。这些研究的结果可以为控制骨合成代谢的机制提供基本的理解。