EARLY RESPONSE PATTERNS IN DIFFERENTIATING OSTEOBLASTS

由于其高发病率和破坏性的社会经济后果， 骨质疏松症是老年人口中的一种重要疾病。这种病 每年造成150万人骨折，其中包括25万人的髋部骨折 美国。髋部骨折后，50%的幸存者不能 再次独立行走，30%-50%需要长期护理。这个 骨质疏松症的成本估计为每年70亿至100亿美元。 美国。治疗和预防本病的基本生理学基础 必须了解骨细胞生物学的调控机制。二十烷类化合物 (如前列腺素、白三烯等)是目标的关键组件 细胞对各种刺激物的早期反应，包括生长因子， 细胞因子和荷尔蒙。虽然二十烷类化合物的新陈代谢已经在 几种成骨细胞系统和骨器官培养中，我们的 关于它们当地生产的知识仍然存在。虽然二十烷类化合物 生产是对刺激的早期反应(改变的生产是 几分钟内明显)大多数研究人员(仅)测量了PGE2 在治疗后几小时或几天内出院。这些数据可能不会反映 该信号转导通路在受刺激时的动态响应 成骨细胞。此外，选择二十烷类化合物的先验 测量增加了其他未检查的主要反应的可能性 二十烷类动物家族的成员将被怀念。这是一个至关重要的问题 因为不同的二十烷类化合物往往会产生相反的生物效应。 目前，即使是人类成骨细胞产生的二十烷类化合物 细胞是未知的。因此，二十烷类化合物的代谢将在 正常成人成骨样细胞来源于骨小梁 外植体。HOB细胞作为人体模型系统的应用 成骨细胞避免了跨物种引入的潜在并发症 研究和自发性疾病中常见的异常细胞反应 变形金刚。HOB细胞是部分分化的类固醇。 反应灵敏。1，25(OH)2D3诱导分化对HOB细胞的影响 将检查二十烷类化合物的代谢情况。二十烷基类化合物释放后 促骨药雌激素、转化生长因子β、甲状旁腺素、白介素1的治疗 和IGF-I将在NAIVE和1，25(OH)2D3处理的滚刀中进行研究和比较 细胞。这些研究将集中于短期内二十烷类化合物的生产。 孵化时间(120分钟或更短)。大多数分析最初将使用高效液相色谱法 以检查HOB细胞产生的二十烷基类化合物的阵列。跟进 研究将使用特定的抗血清进行定量。这部作品 将定义HOB细胞二十烷类代谢的特征，以及 确定差异化对这些产品生产的影响 生物活性脂类。对HOB细胞二十烷基糖代谢的调节作用 促骨剂将在诱导细胞之前和过程中进行研究。 差异化。任何与分化相关的分子机制 二十烷类化合物产量的变化将在HOB细胞水平上进行探讨 磷脂代谢。拟议的调查可能会影响 药物干预的设计与应用 骨质疏松症和其他代谢性骨病。

Because of its high incidence and devastating socio-economic consequences, osteoporosis is an important disorder of the aging population. The disease causes 1.5 million fractures, including 250,000 hip fractures, annually in the United States. Following hip fracture, 50% of the survivors cannot walk independently again and 30-50% require long-term nursing care. The costs of osteoporosis are estimated at $7 to $10 billion annually in the USA. To treat and to prevent this disorder the basic physiological mechanisms regulating bone cell biology must be understood. Eicosanoids (e.g., prostaglandins, leukotrienes, etc.) are key components of a target cell's early responses to various stimulators including growth factors, cytokines, and hormones. While eicosanoid metabolism has been studied in several osteoblastic cell systems and in bone organ cultures, gaps in our knowledge concerning their local production remain. Although eicosanoid production is an early response to stimulation (altered production is evident within minutes) most investigators have measured (only) PGE2 release hours, or days, after treatment. These data may not reflect the dynamic responses of this signal transduction pathway in stimulated osteoblastic cells. Moreover, selecting a priori which eicosanoid to measure increases the probability that major responses in other unexamined members of the eicosanoid family will be missed. This is a critical issue since different eicosanoids often exert opposing biological effects. Presently, even the classes of eicosanoids produced by human osteoblastic cells is unknown. therefore, eicosanoid metabolism will be studied in normal adult human osteoblast-like (hOB) cells derived from trabecular bone explants. The use of hOB cells as the model system for the human osteoblast avoids potential complications introduced in trans-species studies and the abnormal cell responses commonly observed in spontaneous transformants. The hOB cells are partially differentiated and steroid responsive. the impact of 1,25(OH)2D3-induced differentiation on hOB cell eicosanoid metabolism will be examined. Eicosanoid release following treatment with the osteotropic agents estrogen, TGFbeta, PTH, interleukin 1 and IGF-I will be studied and compared in naive and 1,25(OH)2D3-treated hOB cells. These studies will focus on eicosanoid production in short-term incubations (120 minutes or less). Most analyses will initially use HPLC to examine the array of eicosanoids produced by the hOB cells. Follow-up studies will employ specific antisera for quantitative purposes. This work will define the characteristics of hOB cell eicosanoid metabolism, and determine the impact of differentiation on the production of these bioactive lipids. The regulation of hOB cell eicosanoid metabolism by the osteotropic agents will be studied both before and during induced cell differentiation. The molecular mechanism of any differentiation-associated changes in eicosanoid production will be probed at the level of hOB cell phospholipid metabolism. The proposed investigations may influence the design and use of pharmacologic interventions into the progress f osteoporosis and other metabolic bone diseases.