Role of S-nitrosylated Cx43 in normal cardiac contractility

交感神经活动对心脏功能的调节，这种活动发生在运动和运动中 情绪兴奋，被认为促进了细胞间电耦合的增强 心脏。这是必要的，以增加心肌收缩的力量。电气 心脏中的偶联是由心脏间盘的特殊结构所介导的。 心肌细胞，称为缝隙连接通道(GJCs)。这些是细胞间通道 由连接蛋白形成，连接蛋白43(Cx43)是心脏中含量最丰富的。而当 已知Cx43 GJC对于维持电脉冲的传播和 协调心脏收缩，调节心脏GJC偶联的机制 人们对此仍然知之甚少。最近有人提出，β-肾上腺素能刺激，即 用来模拟交感神经活动，诱导一氧化氮(NO)的产生和S亚硝化 心脏蛋白质，这可能占心脏变力作用的三分之一。在这 背景，我们发现Cx43在间盘是严重的S-亚硝化的β-肾上腺素能 刺激。此外，我们还发现，NO增加了由Cx43 GJCs介导的偶联反应。 异源表达系统。因此，我们假设S硝化了Cx43 GJC 增强心肌细胞之间的电耦合，这对协调收缩至关重要。 为了验证我们的假设，我们确定了S的亚硝化位点，并创建了一个敲打小鼠系 这个位置(C271)被丝氨酸取代，我们将用它来评估心脏功能 在活体内。此外，我们将进行生物物理研究，通过以下方式揭示分子机制 其中NO诱导心肌细胞GJC偶联增加。拟议的研究是 创新，因为它的设计揭示了S硝基Cx43 GJCs的新生物物理性质 并提供对心脏传导和收缩能力的机械理解。

Modulation of cardiac function by sympathetic activity, which occurs during exercise and emotional excitement, is thought to promote an augmentation of cell-to-cell electrical coupling in the heart. This is necessary to increase the strength of cardiac muscle contraction. Electrical coupling in the heart is mediated by specialized structures at the intercalated discs of cardiomyocytes, referred to as gap junction channels (GJCs). These are intercellular channels formed by connexin proteins, with connexin 43 (Cx43) being the most abundant in the heart. While is known that Cx43 GJCs are vital to sustain the propagation of electrical impulses and coordinated heart contraction, the mechanisms by which cardiac GJC coupling is regulated remains poorly understood. It has recently been proposed that β-adrenergic stimulation, which is used to mimic sympathetic activity, induces nitric oxide (NO) production and S-nitrosylation of cardiac proteins and this may account for one third of the inotropic effects in the heart. In this context, we found Cx43 at the intercalated disk is heavily S-nitrosylated upon β-adrenergic stimulation. In addition, we found that NO increases coupling mediated by Cx43 GJCs in a heterologous expression system. Accordingly, we hypothesize that S-nitrosylated Cx43 GJCs enhances electrical coupling between cardiomyocytes, which is critical for concerted contractility. To test our hypothesis, we identified the S-nitrosylated site and created a knockin mouse line where this site (C271) was replaced by a serine, and which we will use to assess cardiac function in vivo. In addition, we will perform biophysical studies to unveil the molecular mechanisms by which NO induce increased GJC coupling in the cardiomyocytes. The proposed research is innovative, as it is designed to reveal novel biophysical properties of S-nitrosylated Cx43 GJCs and provide mechanistic understanding on cardiac conduction and contractility.