Gating and Regulation of Connexin Hemichannels

连接蛋白半通道的门控和调节

• 批准号: 10379607
• 负责人: Jorge Enrique Contreras
• 金额: $ 24.29万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10379607
• 关键词: Gating; Regulation; Connexin; Hemichannels

Connexin 43 (Cx43) in the heart is normally expressed at the intercalated disk where it commonly forms junctional channels (gap junctions). Many cardiac diseases produce increased or aberrant expression of Cx43, which results in lateralization of the protein in cardiomyocytes. Our group and others have provided evidence that lateralized Cx43 forms unpaired hyperactive hemichannels (non-junctional channels) at the plasma membrane. Excessive opening of these Cx43 hemichannels is associated with cell death during acute ischemia and cardiac muscular dystrophy. Cell death is thought to result from the loss of electrochemical gradients and small cytoplasmic metabolites through the large and modest selective aqueous pore of connexin hemichannels. We and others have indirect evidence indicating that nitric oxide (NO) opens Cx43 hemichannels, promoting cellular dysfunction in the heart and brain. In addition, we have evidence that under conditions that cause lateralization in cardiomyocytes, Cx43 is S-nitrosated. The molecular mechanisms that cause Cx43 hemichannel opening by NO have not been elucidated, despite the importance this may have in cardiac and other pathologies. We propose that a major contributor to the aberrant opening of undocked hemichannels is Cx43 S-nitrosation. In this proposal, we will take advantage of our expertise in connexin hemichannel biophysics to identify the mechanisms by which NO gates Cx43 hemichannels. Specific Aim 1 will determine whether NO directly opens Cx43 hemichannels via S-nitrosation and identify residues involved. Specific Aim 2 will identify the precise cytoplasmic domain interactions that mediate the effects of NO on Cx43 gating. Specific Aim 3 will determine whether S-nitrosated Cx43 hemichannels promote cell and tissue damage. We plan to accomplish these specific aims using an integrative multidisciplinary approach that combines electrophysiology, mutagenesis, fluorescence and NMR spectroscopy, mass spectrometry, and a cardiac disease model. We expect that our work will contribute to the rational development of new pharmacological strategies to target the specific connexin domains involved in aberrant hemichannel gating. This will allow us to achieve specific therapeutic outcomes, for example, to decrease opening of hyperactive hemichannels during myocardial infarction preventing arrhythmias and tissue damage.

心脏中的连接蛋白43（CX43）通常在插入的磁盘上表达 连接通道（差距）。许多心脏病会产生CX43的增加或异常表达， 这导致心肌细胞中蛋白质的横向化。我们的小组和其他人提供了证据 该侧向CX43在等离子体处形成未配对的多动性半通道（非相关通道） 膜。这些CX43半通道的过度开放与急性期间的细胞死亡有关 缺血和心脏肌肉营养不良。人们认为细胞死亡是由于电化学的损失而导致的 梯度和小细胞质代谢产物，通过大而适度的连接蛋白选择性水孔 半通道。我们和其他人的间接证据表明一氧化氮（NO）打开CX43 半通道，促进心脏和大脑中的细胞功能障碍。此外，我们有证据表明 导致心肌细胞侧向化的疾病，CX43被S-硝化。分子机制 原因CX43 Hemichannel开放尚未阐明，尽管这可能很重要 心脏和其他病理。我们提出，一个主要贡献者的主要贡献者 半通道为CX43 S-硝化。在此提案中，我们将利用我们在连接蛋白方面的专业知识 半通道生物物理学可以识别没有门Cx43半通道的机制。具体目标1将 确定没有直接通过S-硝化打开CX43半通道并识别涉及的残基。 特定的目标2将确定介导NO对CX43的影响的精确细胞质结构域相互作用 门控。特定的目标3将确定S-硝化的CX43半通道是否促进细胞和组织 损害。我们计划使用综合多学科方法来实现这些特定目标 结合电生理学，诱变，荧光和NMR光谱，质谱法和A 心脏病模型。我们预计我们的工作将有助于新的发展 针对与异常半通道门控涉及的特定连接蛋白结构域的药理策略。 例如，这将使我们能够实现特定的治疗结果，例如减少动态的开放 心肌梗塞期间的半通道可防止心律不齐和组织损伤。