EXPRESSION AND REGULATION OF GAP JUNCTION IN BONE CELLS

描述(摘自申请者的摘要)：正常的骨重建 需要不同骨骼细胞的协调活动，并且是 受多种激素和生长因子的影响。骨细胞 通过称为缝隙连接的细胞间水孔进行通信，以及 表达三种不同的缝隙连接蛋白：连接蛋白43(Cx43)、 连接蛋白45(Cx45)和连接蛋白46(Cx46)。Cx43和Cx45位于 成骨细胞的质膜，在那里它们相互作用形成连接 不同的分子渗透率。Cx43和Cx45的相对丰度 是重要的骨骼蛋白表达的关键决定因素，通过 这些细胞。相比之下，仅在细胞内池中发现了Cx46 在成骨细胞中，表明这种缝隙连接蛋白是 只有在特定的特殊情况下才能发挥作用。骨细胞也 表达P2U嘌呤能受体，通过以下途径介导细胞间的通讯 在细胞间传播钙信号。一些荷尔蒙和生长 影响骨重建的因素会改变细胞间的通讯。为 例如，甲状旁腺激素(PTH)和前列腺素E2(PGE2)影响骨骼 并增加Cx43的表达和功能。 这一提议试图检验细胞间通讯 在骨细胞中的空间和时间调节方式允许 细胞间通讯的特定形式。使用分子和 荧光成像技术，这些研究试图(1)定义 缝隙连接蛋白和P2U受体在体内的表达 免疫组织化学和体外实验，在两个生理相关的骨骼中 模型、MC3T3-E1细胞系和大鼠颅骨成骨细胞。 矿化发生和不发生的条件；(2)检查 缝隙连接蛋白和P2U受体在矿化和矿化过程中的作用 非矿化条件；以及(3)检查激素和其他因素的作用 影响骨转换的因素，在这些细胞之间的通讯 模型，并探索观察到的效应发生的机制。它是 建议(由申请人)这些研究将确定 骨细胞之间的生理相关通讯是受调控的， 并提出了治疗代谢性骨病的新方法 骨质疏松症。

DESCRIPTION (Adapted from the Applicant's Abstract): Normal bone remodeling requires the coordinated activities of different bone cells, and is influenced by a variety of hormones and growth factors. Bone cells communicate via intercellular aqueous pores called gap junctions, and express three different gap junction proteins: connexin43 (Cx43), connexin45 (Cx45) and connexin46 (Cx46). Cx43 and Cx45 are found on the plasma membrane of osteoblasts, where they interact to form junctions with different molecular permeabilities. The relative abundance of Cx43 and Cx45 is a critical determinant of the expression of important bone proteins by these cells. In contrast, Cx46 has been found only in an intracellular pool in osteoblastic cells, suggesting that this gap junction protein is functional only in certain specialized circumstances. Bone cells also express P2U purinergic receptor, which mediate cell-cell communication by propagating calcium signaling among cells. Some of the hormones and growth factors that influence bone remodeling alter cell-cell communication. For instance, parathyroid hormone (PTH) and prostaglandin E2 (PGE2) affect bone protein production and also increase the expression and function of Cx43. This proposal seeks to test the hypothesis that intercellular communication is regulated spatially and temporally in bone cells in a manner that allows specific forms of intercellular communication. Using molecular and fluorescence imaging techniques, these studies seek to (1) define the expression of gap junction proteins and P2U receptors in vivo, by immunohistochemistry, and in vitro, in two physiologically relevant bone models, the MC3T3-E1 cell line and rat calvarial osteoblasts, under conditions where mineralization does and does not occur; (2) examine the function of gap junction proteins and P2U receptors under mineralizing and non-mineralizing conditions; and (3) examine the role of hormones, and other factors that influence bone turnover, on cell-cell communication in these models and explore the mechanisms by which observed effects occur. It is suggested (by the applicant) that these studies will define the ways in which physiologically relevant communication among bone cells is regulated, and suggest new approaches to the treatment of metabolic bone diseases such as osteoporosis.