Caveolae and Anesthetic Induced Cardiac Protection

说明(申请人提供)：已知阿片类药物和挥发性麻醉剂可产生心脏保护作用。有证据表明，阿片类药物和挥发性麻醉剂诱导的心脏保护有共同的信号转导途径。涉及心脏保护的分子通路是复杂的。信号转导的一个新概念表明，在质膜的富含脂质的微区中存在着空间组织的信号分子复合体，称为小凹。小窝蛋白是一种富含小窝的蛋白质，为组织、运输和调节信号分子提供了一个支架。我们有证据表明，小窝对于阿片类药物诱导的心脏保护至关重要，并且挥发性麻醉药可以改变小窝的数量和蛋白质含量。我们还发现，在小鼠心肌细胞中过表达小凹蛋白-3(一种肌肉特异的小窝蛋白亚型)可导致：仅在心脏中表达小窝蛋白-3；增加心肌细胞中的小窝数目；正常心功能和增强Akt(参与细胞生存的信号分子)的激活。我们的假设是：1)参与心脏保护的信号分子定位于亚细胞小窝微区，并与小窝蛋白相互作用是阿片类药物和挥发性麻醉药产生的心脏保护所必需的；2)心脏特异性过表达小窝蛋白将增加信号分子与小窝内小窝之间的相互作用，以加强麻醉剂诱导的心脏保护。我们将通过解决以下具体目标来检验这些假设。目的1：确定阿片类麻醉剂和挥发性麻醉剂诱导的心脏保护作用对体外培养心肌细胞小凹的影响。目的2：确定体外培养心肌细胞小窝和小窝蛋白表达的改变是否影响麻醉诱导的心脏保护。目的3：将确定在体内心脏特异性过表达小窝蛋白是否增强麻醉诱导的心脏保护。这项拟议的工作将为接受心脏或非心脏手术的心肌缺血患者或心脏高危患者提供具有特定临床意义的新数据。

DESCRIPTION (provided by applicant): Opioids and volatile anesthetics are known to produce cardiac protection. Evidence suggests a common signal transduction pathway for opioid and volatile anesthetic-induced cardiac protection. The molecular pathways implicated in cardiac protection are complex. An emerging idea in signal transduction suggests the existence of spatially organized complexes of signaling molecules in lipid-rich microdomains of the plasma membrane known as caveolae. Caveolins, proteins abundant in caveolae, provide a scaffold to organize, traffic and regulate signaling molecules. We have evidence that caveolae are vitally important to opioid- induced cardiac protection and that volatile anesthetics can alter the number and protein content of caveolae. We also have shown that cardiac myocyte specific overexpression of caveolin-3 (a muscle specific isoform of caveolin) in mice results in: increased caveolin-3 protein expression exclusively in the heart; increased numbers of caveolae in cardiac myocytes; normal cardiac function and enhanced activation of Akt (a signaling molecule involved in cell survival). Our hypotheses are: 1) The localization of signaling molecules involved in cardiac protection into subcellular caveolar microdomains and the interaction of these molecules with caveolins are essential for cardiac protection produced by opioids and volatile anesthetics; 2) Cardiac specific overexpression of caveolin protein will increase interactions between signaling molecules and caveolin within caveolae to augment anesthetic-induced cardiac protection. We will test the hypotheses by addressing the following specific aims. Aim 1: Will define the effects of opioid- and volatile anesthetic-induced cardiac protection on caveolae in cardiac myocytes in vitro. Aim 2: Will determine if altered caveolae and caveolin expression in cardiac myocytes in vitro affects anesthetic-induced cardiac protection. Aim 3: Will determine if cardiac specific overexpression of caveolin in vivo enhances anesthetic-induced cardiac protection. The proposed work will provide novel data with specific clinical implications for patients with myocardial ischemia or patients at high cardiac risk undergoing cardiac or noncardiac surgery.