SEX STEROIDS, GROWTH FACTORS AND BONE CELL FUNCTION

虽然雌激素(E)可以预防绝经后妇女的骨质丢失和骨质疏松，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E的靶细胞，但不同OB细胞系之间不同浓度的ER和E反应掩盖了E对骨细胞的确切作用。ER-β和黄体酮(P)在卵巢细胞中的作用使这个问题更加复杂。为了弄清不同浓度的ER和ER-α和ER-β物种对卵巢上皮细胞上E的生物学作用的影响，我们的实验室已经培养并鉴定了十几个具有正常OB样特性的条件永生化、成熟的人类OB细胞系(HFOB)。这些细胞已经稳定地表达了不同水平的ER-α(hFOB/ER-α)和ER-β(hFOB/ER-β)，或者这两种细胞，以及一些表达内源性PR的细胞。我们还从人骨髓基质中培养并鉴定了6株永生化前体细胞，它们可以分化为OB-RO脂肪细胞表型。这些hFOB/ER和HMS细胞系将被用来回答以下问题：1)成熟的OB或其前体细胞是E的潜在靶细胞，如果是，需要什么浓度的ER和哪种ER物种(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的功能，如细胞增殖、基质产生和矿化；2)PRA和PRB都是在OB或其前体细胞中表达的，PRA：PRB在OB分化过程中是否发生变化，在含有ER-α或ER-β的细胞中是否存在差异，以及这些PR物种调控哪些基因/过程；3)E和P是否调节OB前体细胞(HMS)的分化，包括基因表达；最后，4)OB衍生的新的可溶性中和受体OPGL及其配体(OPGL)受E调节，进而介导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.