PLASMA MEMBRANE PHOSPHOLIPID SCRAMBLASE IN APOPTOSIS

细胞凋亡中的质膜磷脂扰乱

• 批准号: 6184448
• 负责人: PETER J SIMS
• 金额: $ 43.12万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6184448
• 关键词: apoptosis; flow cytometry; gene targeting; genetically modified animals; growth inhibitors; laboratory mouse; membrane activity; membrane proteins; membrane structure; monoclonal antibody; phosphatidylserines; phospholipids; reticuloendothelial system; tissue /cell culture

An early event in programmed cell death is a remodeling of plasma membrane phospholipids (PL) that results in de novo exposure of phosphatidylserine (PS) and other aminophospholipids at the cell surface. This exposure of thee aminophospholipids is known to promote activation of the plasma complement and coagulation proteases and is implicated in the recognition and clearance of apoptotic cells by the reticuloendothelial system. We recently identified a new plasma membrane protein (PL scramblase) that mediates bi-directional movement of membrane PL and our preliminary data suggest that this protein may also function in amplifying the execution phase of apoptosis. In this Proposal we aim to identify the cellular mechanism(s) responsible for transbilayer movement of plasma membrane PL during programmed cell death, and to determine how this reorganization of cell surface PL is causally related to other changes observed in the apoptotic cell. Our Specific Aims include: (1) To determine whether the egress of PS to the surface of apoptotic cells is mediated through activation of PL scramblase, or through alternative mechanism(s); (2) To identify which of the metabolic changes observed in apoptotic cells are causally linked to the topologic rearrangement of plasma membrane PL; (3) To determine whether the early reorganization of plasma membrane PL is required for the subsequent degradative processes observed during programmed cell death; and (4) To determine whether the level of expression of plasma membrane PL scramblase influences cell susceptibility to growth arrest or to phagocytosis in vitro, and affects either cell survival or cell clearance through the reticuloendothelial system in vivo. It is proposed that these experiments will yield new insight into how activation of the effector pathways of apoptosis is causally related to the transbilayer reorganization of plasma membrane phospholipids in lymphocytes and other cells.

程序性细胞死亡的早期事件是质膜磷脂（PL）的重塑，导致磷脂酰丝氨酸（PS）和其他氨基磷脂在细胞表面重新暴露。 已知氨基磷脂的这种暴露促进血浆补体和凝血蛋白酶的活化，并且涉及网状内皮系统对凋亡细胞的识别和清除。 我们最近发现了一种新的质膜蛋白（PL scramblase），介导膜PL的双向运动，我们的初步数据表明，这种蛋白质也可能在放大细胞凋亡的执行阶段的功能。 在本提案中，我们的目标是确定细胞机制（S）负责跨双层运动的质膜PL在程序性细胞死亡，并确定这种重组的细胞表面PL是如何因果关系的其他变化中观察到的凋亡细胞。 我们的具体目标包括：（1）确定PS向凋亡细胞表面的流出是通过PL乱序酶的激活介导的，还是通过其他机制介导的;（2）鉴定在凋亡细胞中观察到的哪些代谢变化与质膜PL的拓扑重排有因果关系;（3）确定质膜PL的早期重组是否是细胞程序性死亡过程中观察到的后续降解过程所必需的;以及（4）确定质膜PL扰码酶的表达水平是否影响体外细胞对生长停滞或吞噬作用的敏感性，以及是否影响体内细胞存活或通过网状内皮系统的细胞清除。 有人建议，这些实验将产生新的见解如何激活的效应途径的细胞凋亡是因果关系的跨双层重组的质膜磷脂在淋巴细胞和其他细胞。