Effects of reactive oxygen species on brain synaptic plasma membrane Ca2+-ATPase
Effects of reactive oxygen species on brain synaptic plasma membrane Ca2+-ATPase
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DOI：
10.1016/s0891-5849(99)00128-8
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发表时间：
1999-10-01
影响因子：
7.4
通讯作者：
Michaelis, ML
中科院分区：
文献类型：
--
作者：
Zaidi, A;Michaelis, ML
在老年大脑的神经元中，自由胞内钙[Ca2+](i)的调节发生了改变，可能是由于Ca2+转运体活性的降低。质膜Ca2+- atp酶（PMCA）在老龄大鼠脑内Ca2+稳态及其动力学特性变化中起关键作用。这些变化可能是由于与年龄相关的慢性氧化应激导致PMCA氧化修饰。本研究旨在确定神经元PMCA对突触质膜（SPMs）体外暴露于活性氧（ROS）的敏感性。我们研究了三种氧化剂的影响，包括由偶氮引发剂，2,2 '-偶氮比斯2-氨基丙烷二盐酸（AAPH）和4,4 '-偶氮比斯14-氰戊酸（ACVA），过氧化氢（H2O2）和过氧亚硝酸盐（ONOO-）产生的过氧自由基。短暂暴露于这些氧化剂的突触质膜分析了PMCA的功能和结构改变。虽然这三种氧化剂都导致PMCA活性的显著丧失，但ONOO-的影响最明显，其次是过氧自由基和H2O2。氧化处理后PMCA活性的动力学分析显示，V-max降低，K-act无明显变化。免疫印迹显示氧化诱导的PMCA分子交联在还原条件下部分逆转，在尿素的加入下完全逆转。PMCA似乎对ROS的抑制非常敏感，因此可能是老化大脑中氧化应激的目标。其活性的降低可能有助于神经元[Ca2+](i)调节的年龄相关改变。(C) 1999 Elsevier Science Inc.；
The regulation of free intracellular calcium [Ca2+](i) is altered in neurons from the aged brain, possibly due to reductions in the activity of Ca2+ transporters. The plasma membrane Ca2+-ATPase (PMCA) plays a critical role in Ca2+ homeostasis, and its kinetic properties change in aged rat brain. These changes could be due to oxidative modification of PMCA as a result of age-related chronic oxidative stresses. The present studies were undertaken to determine the sensitivity of the neuronal PMCA to in vitro exposure of synaptic plasma membranes (SPMs) to reactive oxygen species (ROS). We examined the effects of three oxidants including peroxyl radicals generated by azo-initiators, 2,2 '-Azobis 2-amidinopropane dihydrochloride (AAPH) and 4,4 '-Azobis 14-cyanovaleric acid (ACVA), hydrogen peroxide (H2O2), and peroxynitrite (ONOO-). Synaptic plasma membranes briefly exposed to these oxidants were analyzed for functional and structural alterations in PMCA. Although all three oxidants led to significant: loss of PMCA activity, the effect of ONOO- was the most potent, followed by peroxyl radicals and H2O2. Kinetic analysis of PMCA activity after oxidant treatment showed decreases in V-max without significant changes in K-act. Immunoblots revealed oxidant-induced cross-linking of PMCA molecules that were partially reversed under reducing conditions and completely reversed with addition of urea. The PMCA appears to be very sensitive to inhibition by ROS and hence may be a target of oxidative stress in the aging brain. Reduction in its activity may contribute to age-related alterations in neuronal [Ca2+](i) regulation. (C) 1999 Elsevier Science Inc.