REGULATION OF CALCIUM CHANNEL EXPRESSION IN OSTEOBLASTS

靶细胞中的钙信号，包括成骨细胞，作为外部刺激的早期效应器，包括那些激素或机械性质的刺激。对于骨，这些钙信号在骨重塑和离子稳态过程中发生的细胞生长分化和偶联中起主要作用。介导钙信号的一个关键分子是位于质膜上的二氢吡啶结合电压敏感钙通道（VSCC）。在对特定刺激的反应中，VSCCs打开，允许细胞外钙进入细胞。VSCC本身是一个大的多亚基蛋白复合物。离子转移亚基，α，已经从几个组织中克隆出来，在那里它显示出组织特异性的结构和功能特性。我们实验室已经在功能和分子水平上鉴定了成骨细胞中的α亚基。在本研究中，我们为成骨细胞VSCC的表达和调控提供了一个系统研究的逻辑方案，重点是α亚基。这三个目标解决了我们的基本假设，即VSCC在控制成骨细胞质膜钙通透性方面发挥重要作用，在激素或机械刺激下发生钙信号的形成过程中。建议结合功能、生化、免疫学、影像学和分子生物学实验。总之，这些研究将为VSCCs在成骨细胞中的表达和功能提供新的见解，因为它们影响正常的骨生理以及骨质流失的病理状况。

Calcium signals in target cells, including osteoblasts, serve as early effectors of external stimuli, including those that are either hormonal or mechanical in nature. For bone, these calcium signals play a major role in cell growth differentiation and coupling which occur during bone remodeling and ion homeostasis. A key molecule involved in mediating calcium signals is the dihydropyridine-binding, voltage sensitive calcium channel (VSCC) that is located in the plasma membrane. In response to specific stimuli, VSCCs open to allow extracellular calcium to enter the cell. The VSCC itself is a large, multi-subunit protein complex. The ion translocating subunit, alpha, has been cloned from several tissues, where it displays tissue-specific structural and functional properties. The alpha, subunit in osteoblasts has been identified at the functional and molecular level in our laboratory. In this proposal, we provide a logical plan for systematic study of the expression and regulation of the osteoblast VSCC, focusing on the alpha, subunit. The three aims address our basic hypothesis that the VSCC serves a vital function in controlling calcium permeability of the osteoblast plasma membrane during development of calcium signals which occur in response to hormonal or mechanical stimuli. A combination of functional, biochemical, immunological, imaging and molecular biological experiments are proposed. Together, these studies will provide new insights to the expression and function of VSCCs in osteoblasts as they impact on normal bone physiology as well as pathological conditions of bone loss.