PERMEABILITY REGULATION IN MITOCHONDRIA

本项目研究了细胞内膜通透性的变化。 肝脏和心脏线粒体。我们的长期目标是：确定 促进溶质移动的结构的性质 过渡后的内膜(通透性缺陷)； 以确定如何在新陈代谢中调节过渡；以及 确定过渡在生理和心理方面所起的作用 病态。拟议的研究围绕着我们最近的 发现免疫抑制环肽环孢素A是 这是一种非常有效和普遍的过渡抑制因素。这是 首先对高活性的抑制剂现象进行鉴定。它的 对线粒体的作用导致了一个工作假说，即 过渡可以通过两种交互机制发生，它们是开放的 内膜内有一个受调节的蛋白质孔，并且 在随后的膜脂相中产生通透性缺陷 磷脂酶A2的作用。 对于所要求的支助期，我们有以下具体目标： 1)鉴定和分离环孢素A结合部位 如果是毛孔，则将其重建为磷脂小泡；2) 鉴定刺激的磷脂代谢的全谱 并确定磷脂是否以及如何 退化与渗透率控制有关；3)表征 线粒体水平上对环孢素敏感的孔 关于已知的激活剂和抑制物的调节 过渡和线粒体对能量的利用；以及 4)测试关于潜在生理作用的工作假说 转移率及其在细胞损伤机制中的作用 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.