REGULATION OF CALCIUM CHANNEL EXPRESSION IN OSTEOBLASTS

靶细胞（包括成骨细胞）中的钙信号充当外部刺激（包括激素或机械性质的刺激）的早期效应物。 对于骨，这些钙信号在骨重建和离子稳态期间发生的细胞生长、分化和偶联中起主要作用。参与介导钙信号的关键分子是位于质膜中的二氢吡啶结合的电压敏感性钙通道（VSCC）。 为了响应特定的刺激，VSCC打开以允许细胞外钙进入细胞。 VSCC本身是一种大的多亚基蛋白复合物。离子转运亚基α已从几种组织中克隆出来，它显示出组织特异性的结构和功能特性。 本实验室已在功能和分子水平上鉴定了成骨细胞中的α 1亚基。 在这个建议中，我们提供了一个逻辑的计划，系统研究成骨细胞VSCC的表达和调控，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的钙渗透性方面起着至关重要的作用，钙信号的产生是对激素或机械刺激的反应。 提出了功能学、生物化学、免疫学、影像学和分子生物学实验的组合。 总之，这些研究将为成骨细胞中VSCC的表达和功能提供新的见解，因为它们影响正常的骨生理学以及骨丢失的病理条件。

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.