SEX STEROIDS, GROWTH FACTORS AND BONE CELL FUNCTION

尽管雌激素可预防绝经后妇女骨质流失和骨质疏松，但其在细胞和分子水平上的作用机制尚不清楚。许多实验室已经证明，成骨细胞（OB）含有雌激素受体（ER），并且是雌激素受体的靶细胞，但由于不同OB细胞系之间雌激素受体浓度和雌激素受体反应的不同，E对骨细胞的确切作用一直模糊不清。er - β和孕酮(P)在OB细胞中的作用使问题进一步复杂化。为了辨别不同浓度的ER和ER α和β物种对E对OB细胞的生物作用的影响，我们的实验室已经产生并表征了十多个条件永生的成熟人OB细胞系（hFOB），这些细胞系显示出正常的OB样特性。这些细胞已被稳定转染，表达不同水平的er - α (hFOB/ er - α), er - β (hFOB/ er - β)，或两个物种，以及一些表达内源性PR。我们还从人骨髓基质（hms）中开发并鉴定了六种永生化前体细胞系，它们可以分化为OB或脂肪细胞表型。这些hFOB/ER和hMS细胞系将用于回答以下问题：1)成熟的OB或其前体是E的潜在靶细胞，如果是，需要多少浓度的ER和哪些ER种类（α或β）来调节早期和晚期基因，包括细胞因子和骨基质蛋白，以及OB功能，如细胞增殖、基质产生和矿化；2) OB或其前体细胞中是否同时表达PRA和PRB种，OB分化过程中PRA:PRB比值是否发生变化，在er - α或er - β细胞中是否存在差异，这些PR种调控哪些基因/过程；3) E和P是否调控OB前体细胞（hMS）分化，包括基因表达；最后4)在hFOB/ER细胞中受E调控的有效的ob衍生的可溶性中和受体，骨蛋白素及其配体（OPGL），它们是否反过来介导E对破骨细胞分化和活性的作用。

Although estrogen (E) administration prevents bone loss and osteoporosis in postmenopausal women, the mechanism of its action at the cellular and molecular level remains unclear. The osteoblasts (OB) have been shown by many laboratories to contain estrogen receptors (ER) and to be target cells for E, but the exact actions of E on bone cells have been obscured by varying concentrations of ER and E responses between different OB cell lines. The roles of the ER-beta species and progesterone (P) in OB cells further complicate the issue. In order to discern the effects that the varying concentrations of ER and the ER-alpha and beta species have on the biological actions on E on OB cells, our laboratories have generated and characterized over a dozen conditionally immortalized, mature, human OB cell lines (hFOB) which display normal OB-like properties. These cells have been stably transfected to express varying levels pf ER-alpha (hFOB/ER-alpha), ER-beta (hFOB/ER-beta), or both species, and several express endogenous PR. We have also developed and characterized six lines of immortalized precursor cells from human bone marrow stroma 9hMS), which can differentiate into either the OB ro adipocyte phenotype. These hFOB/ER and hMS cell lines will be used to answer the following questions: 1) are mature OB or their precursors potential target cells for E, and if so, what concentrations of ER and which ER species (alpha or beta) are required for the regulation of early and late genes, including cytokines and bone matrix proteins, as well as OB functions, such as cell proliferation, matrix production, and mineralization; 2) are both PRA and PRB species expressed in the OB or their precursor cells, does the PRA:PRB ratio change during OB differentiation and differ among the ER-alpha or ER-beta containing cells, and which genes/processes do these PR species regulate; 3) do E and P regulate OB precursor cell (hMS) differentiation, including gene expression; and finally 4) are the potent new OB-derived soluble, neutralizing receptor, osteoprotegrin, and its ligand (OPGL), regulated by E in the hFOB/ER cells and do they in turn mediate the E action on osteoclast cell differentiation and activity.