OSTEOCALCIN SYNTHESIS AND CATABOLISM

描述(改编自申请人的摘要)：骨头的用途 临床研究中的标记物提供了两个重要的见解 生理过程和治疗方法方面的信息 代谢性骨病。骨钙素是研究最广泛的 骨转换的生物标志物，通常被认为是一种 成骨细胞活性指数。然而，对An的临床解释 个别患者的骨钙素测量经常是模棱两可的，而且 并不总是与其他标记物或临床结果相关。这些 困难的出现是因为检测的特异性不同， 关于蛋白质循环形式来源的不确定性， 对其在骨骼中的作用缺乏清晰的认识。在美国的研究 申请实验室证明，除了完整的蛋白质外， 在血液循环中发现骨钙素碎片。他们已经确认了 这些片段中的几个是通过使用具有特定表位的抗体来实现的。 这些单独的骨钙素片段可能是由成骨细胞产生的 和/或破骨细胞，并可能反映与以下相关的不同细胞过程 骨钙素在骨骼中的作用。有见及此，建议的 实验旨在回答以下问题：(1)什么是 循环中骨钙素的形式是什么？建议作出努力，以 进一步鉴定骨钙素的循环形式 免疫分析与高效液相色谱和质谱分析相结合。计划中的 实验将鉴定和定量血清中的这些形式(A) 正常成人和儿童，就年龄、种族和性别而言，以及(B) 代谢性骨病患者。将对结果值进行比较 到标准的临床措施，包括促降钙素，矿物质， 骨吸收指标和骨密度；(2)骨吸收的来源是什么 循环中的骨钙素？申请者将学习(A)骨钙素 生物合成，使用成骨细胞的原代培养，(B)分解代谢 骨钙素，在骨吸收系统中使用兔来源的破骨细胞， 和c)主要片段的代谢清除；和(3)什么是 骨钙素在骨骼中的作用？在这里，骨钙素的潜在作用 骨转换和钙动态平衡将通过研究 骨钙素耗竭小鼠对急、慢性矿物质的反应 荷尔蒙变化。响应性将由标准来确定 钙稳态的测量，包括促钙激素、矿物质、 骨吸收的标记物，骨形成的替代测量 骨密度、组织形态计量学、矿物质质量和含量。

DESCRIPTION (Adapted from the Applicant's Abstract): The use of bone markers in clinical studies has provided both important insights into physiological processes, and information on therapy for the treatment of metabolic bone disease. Osteocalcin is one of the most extensively studied biological markers of bone turnover, and it is generally regarded as an index of osteoblastic activity. However, the clinical interpretation of an osteocalcin measurement in individual patients is often ambiguous and does not always correlate with other markers, or with clinical findings. These difficulties arise because of differences in assay specificity, uncertainties regarding the origin of the circulating forms of the protein, and lack of a clear understanding of its function in bone. Studies in the applicant laboratory demonstrate that in addition to the intact protein, fragments of osteocalcin are found in the circulation. They have identified several of these fragments by the use of antibodies with specific epitopes. These individual fragments of osteocalcin may be produced by osteoblasts and/or osteoclasts, and may reflect distinct cellular processes related to the function of osteocalcin in bone. In light of this, the proposed experiments are designed to answer the following questions: (1) what are the forms of osteocalcin in the circulation? Efforts are proposed to further identify the circulating forms of osteocalcin by using specific immunoassays coupled with HPLC and mass spectral analysis. The planned experimentation will identify and quantitate these forms (a) in serum from normal adults and children, with respect to age, race, and sex, and (b) in patients with metabolic bone disease. The resultant values will be compared to standard clinical measures, including calcitropic hormones, minerals, markers of bone resorption, and bone density; (2) what is the source of circulating osteocalcin? The applicants will study (a) osteocalcin biosynthesis, using primary cultures of osteoblasts, (b) the catabolism of osteocalcin, using rabbit-derived osteoclasts in a bone resorbing system, and c) metabolic clearance of the major fragments; and (3) what is the function of osteocalcin in bone? Here, the potential role of osteocalcin in bone turnover and calcium homeostasis will be examined by studying the response of osteocalcin-deplete mice to acute and chronic mineral and hormonal alterations. Responsiveness will be determined by standard measures of calcium homeostasis, including calcitropic hormones, minerals, markers of bone resorption, alternative measures of bone formation, bone density, histomorphometry, and mineral quality and content in bone.