COLONY STIMULATING FACTOR 1--REGULATION AND ROLE IN BONE

骨质疏松症是绝经后妇女的主要公共卫生问题 还有老年人。它的特点是骨量减少，而且 导致骨折、骨骼畸形和慢性疼痛。尽管 发病机制很复杂，血液中雌激素水平的下降 绝经时间是一个重要的病因。 雌激素的作用之一似乎是保护骨骼免受 甲状旁腺激素(PTH)的吸收作用雌激素停用时间： 因此，更年期增加了骨骼对甲状旁腺素的敏感性，导致 钙动员和骨质流失。因此，理解 骨吸收的机制，特别是甲状旁腺素诱导的骨吸收，将是 对了解骨质疏松症的发病机制具有重要意义。 甲状旁腺素诱导骨吸收的细胞机制尚不清楚。一 假设甲状旁腺素刺激的成骨细胞释放细胞因子， 激活破骨细胞或破骨细胞前体。虽然它的本质是 这些细胞因子是未知的，集落刺激因子(CSF)可能起作用 通过刺激破骨细胞前体细胞的增殖发挥重要作用。 在脑脊液中，只有集落刺激因子-1(CSF-1) 令人信服的证据支持在骨骼重塑中发挥作用。这一证据 包括体内缺乏CSF-1会导致小鼠骨化症，- CSF-1在体外刺激破骨细胞的形成，最后，我们的 观察到CSF-1是主要的集落刺激活性 成骨细胞对甲状旁腺激素的反应。 尽管越来越多的证据表明CSF-1在破骨细胞中起着关键作用 发展，但对其调节和机制知之甚少。 骨骼的作用。因此，本提案的目标是：1) 甲状旁腺激素对成骨细胞分泌CSF-1的调节作用 甲状旁腺激素诱导脑脊液-1基因上调的机制探讨 表达，并通过检查涉及的细胞内信号机制 2)检测成骨细胞分泌CSF-1的能力。 对其他骨吸收药物的反应；3)确定CSF-1的作用 在骨吸收方面使用器官培养系统；以及4)表征 破骨细胞中脑脊液-1受体的表达及其调控 通过促骨剂。 我们期望这些研究将有助于阐明脑脊液-1‘S在骨骼中的作用 重塑，这可能是其发病机制中的一个重要因素 骨质疏松。

Osteoporosis is a major public health problem among post-menopausal women and the elderly. It is characterized by a reduction in bone mass, and leads to fractures, skeletal deformities and chronic pain. Although the pathogenesis is complex, the fall in circulating estrogen levels at the time of menopause is an important etiologic factor. One effect of estrogen appears to be to protect the skeleton from the resorptive action of parathyroid hormone (PTH). Estrogen withdrawal at menopause thus increases the sensitivity of the skeleton to PTH, causing mobilization of calcium and bone loss. Therefore understanding the mechanism of bone-resorption, especially that induced by PTH, will be important to understanding the pathogenesis of osteoporosis. The cellular mechanisms of PTH-induced bone resorption are unclear. One hypothesis is that PTH-stimulated osteoblasts release cytokines which activate osteoclasts or osteoclast precursors. Although the nature of these cytokines is unknown, the colony stimulating factors (CSF's) may play an important role by stimulating proliferation of osteoclast precursors. Of the CSF's, only for colony stimulating factor-1 (CSF-1) is there convincing evidence supporting a role in bone remodelling. This evidence includes that deficiency of CSF-1 in vivo causes osteopetrosis in mice, - that CSF-1 stimulates osteoclast formation in vitro, and finally, our observation that CSF-1 is the principal colony stimulating activity secreted by osteoblasts in response to PTH. Although mounting evidence suggests a critical role for CSF-1 in osteoclast development, little is known about of its regulation and mechanism of action of bone. The goals of the present proposal are therefore: 1) to study the regulation of PTH-induced CSF-1 production in osteoblasts by examining the mechanism of PTH-induced up-regulation of CSF-1 gene expression, and by examining intra-cellular signalling mechanisms involved in CSF-1 secretion; 2) to examine CSF-1 production by osteoblasts in response to other bone-resorbing agents; 3) to determine the role of CSF-1 in bone resorption using organ culture systems; and 4) to characterize the expression of the CSF-1 receptor in osteoclasts, and examine its regulation by osteotropic agents. We expect that these studies will help clarify CSF-1's role in bone remodelling, which may be an important factor in the pathogenesis of osteoporosis.