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.

性状（由申请人提供）：4-雌激素-3 α，17 β-二醇（estren）是雌激素（ER）或雄激素（AR）受体的合成配体，代表一类新型的非遗传性雌激素样信号传导（ANGELS）激活剂，这些化合物在体外和体内忠实地再现了雌二醇对成骨细胞和破骨细胞凋亡的非遗传性作用，但缺乏经典雌激素的遗传性作用。与雌二醇相比，雌激素已被证明具有不同的生物学效应。与雌二醇不同，雌激素对女性或男性生殖器官没有影响，但可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，高于雌激素充分对照组的水平。鉴于雌激素与经典雌激素或其他抗重塑药物相比具有独特的骨骼特征，将对雌激素的上级作用不仅来自其对骨细胞凋亡的有利作用，还来自其他机制的假设进行检验。在直接导致这种应用的研究中，探索了与雌二醇不同，雌激素可能促进成骨细胞祖细胞的定型和/或分化的假设。雌激素通过ER/AR依赖性、激酶介导的BMP-2和Wnt信号转导增强诱导谱系定型和向成骨细胞分化。在这些作用中，雌二醇和二氢睾酮的效力比雌激素低三到四个数量级。与所声称的雌二醇的促分化作用不同，雌二醇的促分化作用只能在通过ER α cDNA转染人工增加ER α表达的细胞中显示，雌激素的促分化作用在表达低水平内源性ER和AR的骨细胞中是可证实的。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以下方式阐明：（1）确定配体/受体相互作用的特异性和（2）BMP和Wnt信号传导参与鼠和人成骨细胞祖细胞和体内骨中的这些作用。性类固醇虽然具有非基因向性信号传导的能力，但其诱导谱系定型和促进成骨细胞分化的能力与雌激素不同，其机制也将通过（3）寻找对细胞因子、激酶、BMP和Wnt以及信号传导途径的基因向性反调节作用来寻求解释。这些研究结果可为进一步了解控制骨质疏松的机制提供必要的依据。