ROLE OF CONNEXIN43 IN REGULATION IN CARDIAC FUNCTION

我们的长期目标是：a)表征心脏缝隙连接调节的分子机制和 B)确定该条例对心脏功能的影响。我们之前的研究已经 以调节连接蛋白43(Cx43)的结构基础为中心，Cx43是最丰富的心脏缝隙 连接蛋白。利用外源表达系统，我们已经证明了 Cx43(Cx43CT)作为一个调节结构域。在这里，我们提出：a)Cx43CT结构域的完整性 对于天然心脏缝隙连接的调节是必不可少的，并且b)这种调节在特定的 缺血事件后的形态和电生理变化。 心脏缝隙连接调节的研究由于缺乏适当的实验而受到阻碍。 Cx43CT域的功能可以直接和具体更改的模型。最近， Willecke实验室开发了一种“敲除/敲入”小鼠品系，其中编码野生型的基因 Cx43被一种缺少大部分CT结构域的截断形式所取代。这些老鼠给我们带来了 第一个直接记录Cx43CT结构域在以下方面的作用的生物系统：1)生物物理性质和 心脏缝隙连接的pH门控。2)Cx43内化对低细胞内pH(Phi)或 全球缺血。3)成年小鼠脑室电生理行为对低pH和 缺血症。 总体而言，这些研究将为我们理解糖尿病的分子机制提供基础数据。 心脏缝隙连接的调节及其在健康和疾病中对心脏功能的作用。

Our long-term goals are: a) to characterize the molecular mechanisms of cardiac gap junction regulation and b) to identify the consequences of the regulation on the function of the heart. Our previous studies have centered on the structural bases for the regulation of Connexin43 (Cx43), the most abundant cardiac gap junction protein. Using exogenous expression systems, we have shown that the carboxyl terminal region of Cx43 (Cx43CT) acts as a regulatory domain. Here, we propose that: a) the integrity of the Cx43CT domain is essential for the regulation of native cardiac gap junctions and b) this regulation plays a key role in specific morphological and electrophysiological changes that follow the ischemic event. Studies on cardiac gap junction regulation have been hindered by the lack of an appropriate experimental model where the function of the Cx43CT domain can be directly and specifically altered. Recently, the Willecke laboratory developed a "knock-out/knock-in" mouse line where the gene coding for the wild-type Cx43 was replaced with a truncated form that lacks most of the CT domain. These mice present us with the first biological system to document directly the role of Cx43CT domain on: 1) The biophysical properties and pH gating of cardiac gap junctions. 2) The internalization of Cx43 in response to low intracellular pH (pHi) or global ischemia. 3) The electrophysiological behavior of adult murine ventricle in response to low pHi and ischemia. Overall, these studies will offer data fundamental to our understanding of the molecular mechanisms of regulation of cardiac gap junctions and their role in heart function in health and disease.