PLASMA MEMBRANE PHOSPHOLIPID SCRAMBLASE IN APOPTOSIS

细胞凋亡中的质膜磷脂扰乱

• 批准号: 6537714
• 负责人: PETER J SIMS
• 金额: $ 47.52万
• 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/6537714
• 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.

细胞程序性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。氨基磷脂的这种暴露被认为促进了血浆补体和凝血酶的激活，并与网状内皮系统对凋亡细胞的识别和清除有关。我们最近发现了一种新的质膜蛋白(PL Scramblase)，它可以介导膜PL的双向运动，我们的初步数据表明，该蛋白也可能在放大细胞凋亡的执行阶段发挥作用。在这项建议中，我们的目的是确定在细胞程序性死亡过程中负责质膜PL跨双层移动的细胞机制(S)，并确定这种细胞表面PL的重组与在凋亡细胞中观察到的其他变化之间的因果关系。我们的具体目标包括：(1)确定PS向凋亡细胞表面的外流是通过PL扰乱酶的激活还是通过替代机制(S)；(2)确定在凋亡细胞中观察到的哪些代谢变化与质膜PL的拓扑重排有关；(3)确定在细胞程序性死亡过程中观察到的随后的降解过程是否需要质膜PL的早期重组；以及(4)确定质膜PL扰乱酶的表达水平是否在体外影响细胞对生长停滞或吞噬的敏感性，以及在体内是否影响细胞通过网状内皮系统的存活或清除。有人认为，这些实验将对如何激活凋亡效应通路与淋巴细胞和其他细胞中质膜磷脂的跨双层重组产生新的认识。