L-type channel trafficking and modulation in heart

总结 心肌L型钙通道在心肌兴奋-收缩耦联、动作电位、心肌细胞凋亡、心肌细胞凋亡等方面起着重要作用 持续时间和基因表达。CaV1.2功能异常，包括增加长开放模式 门控和减弱的肾上腺素能反应与心力衰竭和肥大有关。的 CaV1.2的激活增加，反过来，触发Ca 2+响应信号通路，这有助于 心力衰竭和肥大的发病机制。将CaV1.2适当靶向不同的表面位点，以及 激素调节它们的活性，对于正常的心脏生理是至关重要的。心脏Cav1.2与 影响通道运输、定位、周转和功能的大型超分子复合物。多 关于CaV1.2运输和调节机制的流行教条来自于 使用在异源表达系统中重构的重组通道的研究。不幸的是， 然而，至少有一些关于β-肾上腺素能受体的运输和调节的最关键的问题， 心肌细胞中的激动剂不能使用异源表达进行评估，可能是因为独特的 心肌细胞的细胞内环境在其他地方不能复制。在上一个融资周期，我们 开发并实施了创新方法，以探索CaV1.2贩运和β- 肾上腺素能调节直接在心肌细胞。使用这种方法，我们的研究结果表明，成人中β-少α1C 心肌细胞产生不受PKA调节的具有正常基础活性的CaV1.2通道， 第一次有机会探测这种调制对交感神经调节的相对贡献， 飞行反应。我们提出了三个目标，建立在我们以前的研究结果，并旨在深化 对心脏中CaV1.2调节的机制的理解：（1）确定CaV1.2与CaV1.1C结合的作用， 调节体内心肌收缩力;（2）确定β-淀粉样蛋白亚基使β-淀粉样蛋白亚基能够调节心肌收缩力的机制。 CaV1.2的肾上腺素能调节。(3)阐明β依赖性和β非依赖性CaV1.2的作用机制 渠道贩运。这三个目标应提供有关监管的关键新理解， 心肌细胞中的Ca 2+内流，与理解心脏病理学和心肌细胞中的Ca 2+内流高度相关。 负责心脏兴奋-收缩偶联和肾上腺素能调节的分子机制 心脏Ca 2+通道。

SUMMARY The cardiac L-type Ca2+ channel plays a key role in cardiac excitation-contraction coupling, action potential duration, and gene expression. Abnormalities in CaV1.2 function, including increased long-opening-mode gating and blunted adrenergic responsiveness, are associated with heart failure and hypertrophy. The increased activation of CaV1.2, in turn, triggers Ca2+-responsive signaling pathways, which contribute to the pathogenesis of heart failure and hypertrophy. Proper targeting of CaV1.2 to distinct surface sites, and hormonal regulation of their activity, is vital for normal cardiac physiology. Cav1.2 in heart is associated with large supramolecular complexes that impact on channel trafficking, localization, turnover, and function. Much of the prevailing dogma relating to mechanisms underlying CaV1.2 trafficking and modulation is derived from studies using recombinant channels reconstituted in heterologous expression systems. Unfortunately, however, at least some of the most critical questions regarding trafficking and regulation by -adrenergic agonists in cardiomyocytes cannot be assessed using heterologous expression, likely because the unique intracellular environment of cardiomyocytes is not reproduced elsewhere. In the previous funding period, we developed and implemented innovative methods to probe determinants underlying CaV1.2 trafficking and β- adrenergic regulation directly in cardiomyocytes. Using this approach, our findings that β-less α1C in adult cardiomyocytes generate CaV1.2 channels with normal basal activity that are not regulated by PKA provide the first opportunity to probe the relative contribution of this modulation to sympathetic regulation in the fight or flight response. We propose three Aims that build on our previous findings, and designed to deepen mechanistic understanding of CaV1.2 regulation in heart: (1) Determine the role of CaV binding to 1C in regulating cardiac contractility in vivo; (2) To determine the mechanism(s) by which  subunits enable - adrenergic regulation of CaV1.2. (3) To elucidate the mechanisms of β-dependent and β-independent CaV1.2 channel trafficking. The three Aims, which should provide key new understandings concerning the regulation of Ca2+ influx in cardiomyocytes, are highly relevant towards understanding cardiac pathologies and the molecular mechanisms responsible for cardiac excitation-contraction coupling and adrenergic modulation of the cardiac Ca2+ channel.