Effect of S-nitrosoglutathione on renal mitochondrial function: a new mechanism for reversible regulation of manganese superoxide dismutase activity?
Effect of S-nitrosoglutathione on renal mitochondrial function: a new mechanism for reversible regulation of manganese superoxide dismutase activity?
复制标题
DOI：
10.1016/j.freeradbiomed.2012.12.001
复制
发表时间：
2013-03
影响因子：
7.4
通讯作者：
MacMillan-Crow LA
中科院分区：
文献类型：
--
作者：
Patil NK;Saba H;MacMillan-Crow LA
线粒体是所有细胞过程的核心，因为它们提供各种代谢过程所需的大部分能量。一氧化氮已被证明在线粒体功能的调节中具有许多作用。线粒体有大量的谷胱甘肽（GSH> 5-10 mM）。一氧化氮可以与谷胱甘肽反应生成生理分子S-亚硝基谷胱甘肽（GSNO）。近年来，GSNO对线粒体功能的影响已被深入研究，并且已显示GSNO靶向几种线粒体电子传递链复合物蛋白。在这项研究中，我们研究了GSNO对线粒体功能正常大鼠近端肾小管肾细胞（NRK细胞）。GSNO处理NRK细胞导致线粒体膜去极化和线粒体复合物IV和锰超氧化物歧化酶（MnSOD）的活性显着降低。MnSOD是一种重要的内源性抗氧化酶，可清除线粒体中过量的超氧化物自由基。MnSOD活性的降低与其蛋白质水平的降低无关，用二硫苏糖醇（一种强巯基还原剂）处理NRK细胞裂解物使MnSOD活性恢复到对照值。已知GSNO引起S-亚硝基化和S-谷胱甘肽化，其涉及分别向半胱氨酸残基的蛋白质巯基（SH）添加NO和GS基团。内源性GSH是细胞蛋白S-谷胱甘肽化的重要介质，目前的研究表明，GSH是必需的MnSOD失活后，GSNO或二酰胺处理大鼠肾细胞以及在离体肾脏。进一步的研究表明，GSNO导致谷胱甘肽化的MnSOD，但谷胱甘肽化的重组MnSOD没有失活。这表明，一个更复杂的途径，可能涉及多种蛋白质的参与，导致MnSOD失活后GSNO处理。这些研究的主要亮点是二硫苏糖醇可以恢复GSNO处理后MnSOD活性的事实。据我们所知，这是第一个研究表明，MnSOD活性可以在体内可逆调节，通过巯基残基的机制。
Mitochondria are at the heart of all cellular processes as they provide the majority of the energy needed for various metabolic processes. Nitric oxide has been shown to have numerous roles in the regulation of mitochondrial function. Mitochondria have enormous pools of glutathione (GSH≈5–10 mM). Nitric oxide can react with glutathione to generate a physiological molecule, S-nitrosoglutathione (GSNO). The impact GSNO has on mitochondrial function has been intensively studied in recent years, and several mitochondrial electron transport chain complex proteins have been shown to be targeted by GSNO. In this study we investigated the effect of GSNO on mitochondrial function using normal rat proximal tubular kidney cells (NRK cells). GSNO treatment of NRK cells led to mitochondrial membrane depolarization and significant reduction in activities of mitochondrial complex IV and manganese superoxide dismutase enzyme (MnSOD). MnSOD is a critical endogenous antioxidant enzyme that scavenges excess superoxide radicals in the mitochondria. The decrease in MnSOD activity was not associated with a reduction in its protein levels and treatment of NRK cell lysate with dithiothreitol (a strong sulfhydryl-group-reducing agent) restored MnSOD activity to control values. GSNO is known to cause both S-nitrosylation and S-glutathionylation, which involve the addition of NO and GS groups, respectively, to protein sulfhydryl (SH) groups of cysteine residues. Endogenous GSH is an essential mediator in S-glutathionylation of cellular proteins, and the current studies revealed that GSH is required for MnSOD inactivation after GSNO or diamide treatment in rat kidney cells as well as in isolated kidneys. Further studies showed that GSNO led to glutathionylation of MnSOD; however, glutathionylated recombinant MnSOD was not inactivated. This suggests that a more complex pathway, possibly involving the participation of multiple proteins, leads to MnSOD inactivation after GSNO treatment. The major highlight of these studies is the fact that dithiothreitol can restore MnSOD activity after GSNO treatment. To our knowledge, this is the first study showing that MnSOD activity can be reversibly regulated in vivo, through a mechanism involving thiol residues.