PERMEABILITY REGULATION IN MITOCHONDRIA

本项目研究了细胞内膜通透性的转变， 肝脏和心脏线粒体。 我们的长期目标是：确定 促进溶质运动的结构的性质 内膜发生转变（渗透性缺陷）; 以确定如何通过代谢调节过渡;以及 确定过渡在生理和 病理状态。 这些拟议的研究围绕着我们最近的 发现免疫抑制环肽，环孢菌素A， 是一种强效且通用的转化抑制剂 这是 第一高活性抑制剂的现象被确定。 其 对线粒体的作用导致了一个工作假设， 过渡可以通过两种相互作用的机制发生， 内膜内的受调节的蛋白质孔， 随后在膜脂质相中产生渗透性缺陷 磷脂酶A2的作用。 对于所要求的支持期，我们有以下具体目标： 1)表征和分离环孢菌素A结合位点， 将其重组为磷脂囊泡（如果是孔）; 2） 确定刺激磷脂代谢的全谱， 伴随着过渡，并确定是否以及如何磷脂 降解与渗透率控制有关; 3）表征 在线粒体水平上推定的环孢素敏感孔， 关于通过已知的活化剂和抑制剂调节 转换和关于线粒体的能量利用;以及 4)为了测试关于潜在的生理作用的工作假设， 过渡及其参与细胞损伤的机制， 氧化应激

This project investigates the inner membrane permeability transition in liver and heart mitochondria. Our long-range goals are: to determine the nature of the structure which facilitates solute movements across the inner membrane following the transition (the permeability defect); to determine how the transition is regulated metabolically; and to identify the roles that the transition plays in physiological and pathological states. The proposed studies revolve around our recent discovery that the immunosuppressive cyclic peptide, cyclosporin A, is a highly potent and universal inhibitor of the transition. This is the first high activity inhibitor of the phenomenon to be identified. Its actions on mitochondria have led to the working hypothesis that the transition can occur by two interactive mechanisms which are the opening of a regulated proteinaceous pore within the inner membrane, and the creation of permeability defects in the membrane lipid phase subsequent to the action of phospholipase A2. For the support period requested, we have the following specific aims: 1) to characterize and isolate the cyclosporin A binding site and to reconstitute it into phospholipid vesicles if it is the pore; 2) to identify the full spectrum of stimulated phospholipid metabolism which accompanies the transition and to ascertain if and how phospholipid degradation is related to permeability control; 3) to characterize the putative cyclosporin-sensitive pore at the mitochondrial level with respect to regulation by known activators and inhibitors of the transition and with respect to energy utilization by mitochondria; and 4) to test working hypotheses on potential physiological roles of the transition and its involvement in mechanisms of cell injury initiated by oxidative stress.