Cx43-hemichannels in Regulation of Osteocyte Responses to Mechanical Stress

描述(申请人提供)：由连接蛋白43(Cx43)形成的缝隙连接在骨形成和骨重建所必需的骨细胞之间的信号传递中起着重要作用。与其他类型的骨细胞相比，骨细胞表达大量的Cx43；然而，它们只通过树突的尖端与其他骨细胞形成缝隙连接。我们的初步数据表明，除了缝隙连接外，原代骨细胞和类似骨细胞-1的MLO-Y4细胞还表达功能性的Cx43形成半管，这些半管介导骨细胞对机械应力的即时反应。核心假设是，Cx43形成的半槽骨在调节骨细胞对机械应变的反应中具有基本的、但又不同于缝隙连接的功能，而a5-整合素调节半槽骨的开放。我们将追求两个特定的目标：1)确定形成Cx43的半管在骨细胞对机械应力的反应中所起的重要作用；2)确定a5整合素是否调节流体切应力诱导的半管的开放。这一提议的创新和重要方面是发现了Cx43形成的半通道在调节骨细胞对机械应变的反应中的非传统作用的新机制。这项研究将利用生化、分子和功能技术结合独特的机械工程应用提供全面的培训。

DESCRIPTION (provided by applicant): Gap junctions formed by connexin 43 (Cx43) play an important role in transmitting signals between bone cells essential for bone formation and remodeling. Osteocytes express large amounts of Cx43 compared with other bone cell types; however, they only form gap junctions with other osteocytes through the tips of their dendritic processes. Our preliminary data suggests that in addition to gap junctions, primary osteocytes and osteocyte-1 like MLO-Y4 cells express functional Cx43-forming hemichannels and these hemichannels mediate the immediate response of osteocytes to mechanical stress. The central hypothesis is that hemichannels formed by Cx43 have essential, yet distinct functions from gap junctions in the regulation of the osteocytic response to mechanical strain, and a5-integrin regulates the opening of hemichannels. Two specific aims will be pursued: 1) Identify the essential roles that Cx43-forming hemichannels play in osteocyte responses to mechanical stress; 2) Determine if a5 integrin regulates the opening of hemichannels induced by fluid flow shear stress. The innovative and significant aspects of this proposal are the discovery of novel mechanisms for unconventional roles of Cx43-forming hemichannels in regulating osteocyte response to mechanical strain. This study will provide comprehensive training using biochemical, molecular, and functional techniques combined with unique mechanical engineering applications.