Wen Jian-Jun, Garg Nisha
Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
Free Radic Biol Med. 2004 Dec 15;37(12):2072-81. doi: 10.1016/j.freeradbiomed.2004.09.011.
Previously, we have shown deficiencies in the activities of the mitochondrial respiratory complexes and reduced mitochondrial ATP generation capacity in chagasic hearts infected by Trypanosoma cruzi. In this study, we determined whether the oxidative stress that occurs in response to T. cruzi infection contributes to the catalytic impairment of respiratory complexes and to subsequent mitochondrial dysfunction in murine myocardium. Our data show that oxidative injuries, as determined by the levels of lipid peroxides and protein carbonyls, are incurred in cardiac mitochondria as early as 3 days postinfection and persist throughout the infection and disease. The individual components of the respiratory complexes were separated by two-dimensional, blue-native gel electrophoresis, and carbonyl adducts were detected by Western blotting. We observed substantial carbonylation of the specific subunits of mitochondrial respiratory complexes in infected murine hearts. Of note is the oxidative modification of NDUFS1, NDUFS2, and NDUFV1, which form the catalytic core of the CI complex; UQCRC1, UQCRC2, and UQCRQ, the subunits of the core subcomplex, and UQCRH and CYC1, which form the cyt c(1) subcomplex of CIII; and a gamma chain that is essential for ATP synthesis by CV complex. The extent of oxidative modifications of the subunits correlated with the catalytic defects of the respiratory complexes in the infected myocardium. Taken together, our data demonstrate that respiratory complexes are oxidatively damaged in response to the stress of T. cruzi infection. These data also suggest involvement of the specific susceptibility of the protein subunits, and not generalized mitochondrial oxidative damage in respiratory chain impairment of chagasic hearts.
此前，我们已表明，感染克氏锥虫的恰加斯病心脏中线粒体呼吸复合体活性存在缺陷，线粒体ATP生成能力降低。在本研究中，我们确定了克氏锥虫感染引发的氧化应激是否会导致小鼠心肌中呼吸复合体的催化损伤及随后的线粒体功能障碍。我们的数据表明，早在感染后3天，心脏线粒体就会发生氧化损伤，这可通过脂质过氧化物和蛋白质羰基水平来确定，且在整个感染和疾病过程中持续存在。通过二维蓝色天然凝胶电泳分离呼吸复合体的各个组分，并通过蛋白质免疫印迹法检测羰基加合物。我们观察到感染小鼠心脏中线粒体呼吸复合体的特定亚基存在大量羰基化。值得注意的是，构成CI复合体催化核心的NDUFS1、NDUFS2和NDUFV1；核心亚复合体的亚基UQCRC1、UQCRC2和UQCRQ，以及构成CIII的细胞色素c1亚复合体的UQCRH和CYC1；还有对CV复合体ATP合成至关重要的γ链都发生了氧化修饰。亚基氧化修饰的程度与感染心肌中呼吸复合体的催化缺陷相关。综上所述，我们的数据表明，呼吸复合体在克氏锥虫感染应激下会受到氧化损伤。这些数据还表明，蛋白质亚基的特异性易感性参与其中，而非广义的线粒体氧化损伤导致恰加斯病心脏呼吸链损伤。
