Caveolae, mitochondria, and cardiac protection

 描述（由申请人提供）：心肌梗死（MI）仍然是美国的主要死亡原因。缺血预处理是保护心脏免受MI的最有益的干预措施之一，尽管精确的靶点以及因此产生预处理和预防MI的特定治疗方法尚不清楚。为了解决这些知识上的差距，我们先前的资助申请假设IPC介导的小窝蛋白（一种在脂筏膜微结构域（小窝）中发现的支架蛋白）的调节对于将肌膜偶联到线粒体以及在缺血-再灌注（I/R）损伤的情况下调节线粒体功能和产生活性氧（ROS）至关重要。Caveolin可以保护心脏免受缺血性损伤：IPC诱导的Caveolin向线粒体的转移导致线粒体结构和功能的稳定。我们发现这是一个普遍的机制：它发生在C。优雅和癌症将小窝蛋白特异性靶向线粒体复制了这种IPC样效应，但缺乏心脏小窝蛋白的小鼠不能进行预处理。这些数据强烈暗示了小窝蛋白在质膜-线粒体通讯和IPC中的重要性。然而，窖蛋白稳定缺血心肌的确切机制尚不清楚。细胞膜是动态实体，通过其蛋白质和脂质的组成在两种环境之间形成屏障。除了质膜之外，细胞内结构如线粒体、内质网、细胞核和高尔基复合体的功能部分源自它们的膜。I/R损伤损伤肌膜。IPC的主要益处包括其稳定肌膜超微结构、保护线粒体膜电位和减少ROS的产生。我们发现IPC可以将质膜小窝蛋白转移到线粒体，这表明小窝蛋白调节这两个隔室中的膜功能，并且其在线粒体中表达的增加可能是细胞适应应激的关键机制。我们假设：在缺血应激后和响应于IPC，肌膜和线粒体膜中小窝蛋白的积累增加膜修复以限制损伤并稳定细胞功能。因此，增强小窝蛋白表达和与修复过程的相互作用将提供治疗缺血再灌注损伤的治疗方法。下面的具体目标将测试这一假设：目的1：定义在I/R损伤的肌膜修复小窝蛋白的作用。目的2：明确小窝蛋白在I/R损伤时线粒体膜动力学和功能中的作用。

 DESCRIPTION (provided by applicant): Myocardial infarction (MI) remains a major cause of death in the United States. Ischemic preconditioning is one of the most beneficial interventions to protect the heart from MI, though a precise target and therefore a specific therapeutic approach to produce preconditioning and prevent MI are not known. To address these gaps in knowledge, our prior grant application hypothesized that IPC-mediated modulation of caveolin, a scaffolding protein found in lipid raft membrane microdomains (caveolae), is critical for coupling the sarcolemma to mitochondria and the regulation of mitochondrial function and generation of reactive oxygen species (ROS) in the setting of ischemia-reperfusion (I/R) injury. Caveolin can protect the heart from ischemic damage: IPC-induced transfer of caveolin to mitochondria leads to stabilization of mitochondrial structure and function. We find that this mechanism is a general one: it occurs in C. elegans and cancer. Specific targeting of caveolin to mitochondria replicates this IPC-like effect but mice that lack cardiac caveolin cannot be preconditioned. Such data strongly implicate the importance of caveolin in plasma membrane-mitochondria communication and in IPC. However, the precise mechanisms by which caveolin stabilizes the ischemic myocardium are not known. Cellular membranes are dynamic entities that create barriers between two environments by their composition of proteins and lipids. In addition to the plasma membrane, the function of intracellular structures such as mitochondria, endoplasmic reticulum, nucleus and Golgi complex, derives in part from their membranes. I/R injury damages sarcolemmal membranes. Key benefits of IPC include its stabilization of sarcolemmal ultrastructure, preservation of mitochondrial membrane potential and reduced generation of ROS. Our finding that IPC can transfer plasma membrane caveolin to mitochondria suggests that caveolin regulates membrane function in these two compartments, and its increase in expression in mitochondria may be a critical mechanism for cellular adaptation to stress. We hypothesize that: The accumulation of caveolin in sarcolemmal and mitochondrial membranes following ischemic stress and in response to IPC increases membrane repair to limit injury and stabilize cellular function. Thus, enhancing caveolin expression and interaction with reparative processes will provide a therapeutic approach to treat ischemia-reperfusion injury. The following specific aims will test this hypothesis: Aim 1: Define the role of caveolin in sarcolemmal membrane repair during I/R injury. Aim 2: Define the role of caveolin in mitochondrial membrane dynamics and function during I/R injury.