Effects of oxidative stress on glial cell membranes

氧化应激对神经胶质细胞膜的影响

基本信息

批准号：
7199377
负责人：
JAMES C LEE
金额：
$ 18.27万
依托单位：
UNIVERSITY OF MISSOURI-COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-01-01 至 2008-12-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The objective of this proposal is to investigate the roles of membrane factors in amyloid-b peptide (A¿)- induced oxidative stress and inflammatory responses in glial cells. Here membrane factors include local membrane phase properties and cytoskeletal linkage of membrane receptors. Ab-induced oxidative stress and inflammation are implicated in Alzheimer's disease (AD). In fact, Ab has been found to induce oxidative stress through activation of NADPH oxidase. Excess reactive oxygen species (ROS) in cells, in turn, cause oxidative damage including lipid peroxidation, oxidation of RNA, DNA, and proteins, which subsequently perturb normal cellular processes, including intracellular signaling and cytoskeleton organization. In this regard, we have previously reported that oxidative stress causes astrocyte membrane to become more gel- like through activations of p38 MARK and of cytosolic phospholipase A2 (cPLA2). Our preliminary results also show Ab42 oligomers induce activation of cPLA2. Since it has been reported that the efficiency of NADPH oxidase activation is dependent of its local membrane environment and our preliminary studies show that the membrane subunit of NADPH oxidase, gp91ph0*, is predominately localized at the high GP domains (i.e. more gel-like membranes) in astrocytes, these findings lead us to hypothesize that Af!*2 induces cPLA2 activation through activations of NADPH oxidase and MAPK pathways to cause glial membranes to become more gel-like, which, in turn, becomes a positive feedback to further amplify the activation of NADPH oxidase to produce ROS. Other membrane factors, such as cytoskeletal linkages of membrane receptors, can also be a fundamental element governing cell functions. It has been reported that Ab42 binds to membrane receptors, CD36, ctePi, CD47 and scavenger receptor class A, resulting in inflammatory responses in microglial cells, which can be suppressed by blocking the binding of Ab42 to one of these receptors using their antibodies. These findings lead us to hypothesize that cooperativity between these membrane receptors is required for AB-induced inflammatory responses in microglial cells and this cooperativity is established through the cytoskeletal linkages of these membrane receptors. Since oxidative stress and inflammation are implicated in AD, our study on how membrane factors involved in the mechanisms of Ab-induced oxidative stress and inflammatory responses in glial cells will prove critical to deepen our understandings in the pathogenesis of AD. Novel biophysical techniques including fluorescence imaged deformation (FIMD) and fluorescent microscopy of LAURDAN, and various biochemical techniques will be applied to accomplish this proposed project.

描述（由申请人提供）：本提案的目的是研究膜因子在淀粉样蛋白-b 肽 (A¿) 诱导的神经胶质细胞氧化应激和炎症反应中的作用，其中膜因子包括局部膜相特性和细胞骨架。 Ab 诱导的氧化应激和炎症与阿尔茨海默病 (AD) 有关。事实上，Ab 已被发现通过激活 A 来诱导氧化应激。 NADPH 氧化酶。反过来，细胞中过量的活性氧 (ROS) 会引起氧化损伤，包括脂质过氧化、RNA、DNA 和蛋白质的氧化，从而扰乱正常的细胞过程，包括细胞内信号传导和细胞骨架组织。我们之前报道过，氧化应激通过激活 p38 MARK 和胞质磷脂酶 A2 (cPLA2) 导致星形胶质细胞膜变得更加凝胶状。我们的初步结果还表明 Ab42 寡聚物诱导 cPLA2 的激活，因为据报道 NADPH 氧化酶激活的效率取决于其局部膜环境，并且我们的初步研究表明 NADPH 氧化酶的膜亚基 gp91ph0* 主要是局部的。在星形胶质细胞的高 GP 结构域（即更多的凝胶样膜）中，这些发现使我们重新认识到 Af!*2 通过以下方式诱导 cPLA2 激活： NADPH氧化酶和MAPK途径的激活导致神经胶质细胞膜变得更加凝胶状，这反过来又成为正反馈，进一步放大NADPH氧化酶的激活以产生ROS其他膜因子，例如膜受体的细胞骨架连接。，也可以是控制细胞功能的基本元件据报道，Ab42 与膜受体、CD36、ctePi、CD47 和 A 类清道夫受体结合。导致小胶质细胞中的炎症反应，可以通过使用其抗体阻断 Ab42 与这些受体之一的结合来抑制炎症反应。这些发现使我们认为这些膜受体之间的合作是 AB 诱导的小胶质细胞炎症反应所必需的。由于氧化应激和炎症与 AD 相关，因此我们研究膜因子如何参与 Ab 诱导的氧化应激机制。神经胶质细胞的炎症反应对于加深我们对 AD 发病机制的理解至关重要，包括荧光成像变形 (FIMD) 和 LAURDAN 荧光显微镜在内的新型生物物理技术，以及各种生化技术将用于完成该项目。