Nitration and inactivation of manganese superoxide dismutase in chronic rejection of human renal allografts
Nitration and inactivation of manganese superoxide dismutase in chronic rejection of human renal allografts
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DOI：
10.1073/pnas.93.21.11853
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发表时间：
1996-10-15
影响因子：
11.1
通讯作者：
Thompson, JA
中科院分区：
文献类型：
--
作者：
MacMillanCrow, LA;Crow, JP;Thompson, JA
慢性排斥反应中的炎症过程仍然是器官移植中一个严重的临床问题。活化的细胞浸润液产生高水平的超氧化物和一氧化氮。这些活性氧物种相互作用形成过氧亚硝酸盐，这是一种有效的氧化剂，可以修饰蛋白质形成3-硝基酪氨酸。我们发现硝基酪氨酸增强免疫染色定位于慢性排斥的人移植肾的肾小管上皮细胞。免疫印迹分析表明，酪氨酸硝化仅限于少数几个特定的多肽。免疫沉淀和氨基酸测序技术确定线粒体中的主要抗氧化酶锰超氧化物歧化酶是酪氨酸硝化的目标之一。总锰超氧化物歧化酶蛋白在排斥肾组织中增加，尤其是在肾小管上皮细胞中；但酶活性显著降低。重组人锰超氧化物歧化酶暴露于过亚硝酸根后，酶活性降低，酪氨酸硝化增加，且呈剂量依赖性(IC50=10mU M)。总而言之，这些观察表明过氧亚硝酸盐在人类移植肾慢性排斥反应的发生和进展中发挥了作用。此外，过氧亚硝酸盐对锰超氧化物歧化酶的失活可能代表了一种普遍的机制，即逐渐增加过氧亚硝酸盐的产生，导致线粒体不可逆转的氧化损伤。
Inflammatory processes in chronic rejection remain a serious clinical problem in organ transplantation. Activated cellular infiltrate produces high levels of both superoxide and nitric oxide. These reactive oxygen species interact to form peroxynitrite, a potent oxidant that can modify proteins to form 3-nitrotyrosine. We identified enhanced immunostaining for nitrotyrosine localized to tubular epithelium of chronically rejected human renal allografts. Western blot analysis of rejected tissue demonstrated that tyrosine nitration was restricted to a few specific polypeptides. Immunoprecipitation and amino acid sequencing techniques identified manganese superoxide dismutase, the major antioxidant enzyme in mitochondria, as one of the targets of tyrosine nitration. Total manganese superoxide dismutase protein was increased in rejected kidney, particularly in the tubular epithelium; however, enzymatic activity was significantly decreased. Exposure of recombinant human manganese superoxide dismutase to peroxynitrite resulted in a dose-dependent (IC50 = 10 mu M) decrease in enzymatic activity and concomitant increase in tyrosine nitration. Collectively, these observations suggest a role for peroxynitrite during development and progression of chronic rejection in human renal allografts. In addition, inactivation of manganese superoxide dismutase by peroxynitrite may represent a general mechanism that progressively increases the production of peroxynitrite, leading to irreversible oxidative injury to mitochondria