Induction of the mitochondrial permeability transition by N-ethylmaleimide depends on secondary oxidation of critical thiol groups.: Potentiation by copper-ortho-phenanthroline without dimerization of the adenine nucleotide translocase
Induction of the mitochondrial permeability transition by N-ethylmaleimide depends on secondary oxidation of critical thiol groups.: Potentiation by copper-ortho-phenanthroline without dimerization of the adenine nucleotide translocase
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DOI：
10.1016/s0005-2728(98)00090-5
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发表时间：
1998-07-20
影响因子：
4.3
通讯作者：
Bernardi, P
中科院分区：
文献类型：
--
作者：
Costantini, P;Colonna, R;Bernardi, P
除了低微摩尔浓度的硫醇氧化剂铜邻菲咯啉[Cu(OP)(2)]给大鼠肝脏线粒体通电外，还会导致通透性转换孔打开，这是环孢素A敏感的通道。用二硫苏糖醇(DTT)还原可以逆转Cu(OP)(2)的作用，这表明二硫醇-二硫化物之间存在相互转化。然而，与所有已知的通过二硫醇氧化作用的气孔诱导剂不同，铜(OP)(2)的作用不能通过低浓度(10-20µM)的N-乙基马来酰亚胺(NEM)处理线粒体来阻止。相反，这些浓度的NEM增强了铜(OP)2的诱导作用。我们发现NEM的这种增强作用被随后添加的DTT所阻断，这表明NEM的增强作用是通过氧化事件而不是通过取代来介导的。我们还发现，在没有氧化剂的情况下，高浓度(0.5-1.0 mM)的NEM的孔诱导也被DTT或β-巯基乙醇还原完全阻止。这些结果强调了氧化事件在通过替代试剂打开毛孔中出人意料的重要性。由于我们发现，铜(OP)(2)或高浓度的NEM并不伴随腺核苷酸转位酶的二聚化，因此，转位酶本身并不是铜(OP)(2)和NEM引发的孔诱导氧化事件的靶标。(C)1998 Elsevier Science B.V.保留所有权利。
Addition to energized rat liver mitochondria of low micromolar concentrations of the thiol oxidant, copper-o-phenanthroline [Cu(OP)(2)], causes opening of the permeability transition pore, a cyclosporin A-sensitive channel. The effects of Cu(OP)(2) can be reversed by reduction with dithiothreitol (DTT), suggesting that a dithiol-disulfide interconversion is involved. However, at variance with all pore inducers known to act through dithiol oxidation, the effects of Cu(OP)(2) are not prevented by treatment of mitochondria with low (10-20 mu M) concentrations of N-ethylmaleimide (NEM). Rather, these concentrations of NEM potentiate the inducing effects of Cu(OP)2. We show that this enhancing effect of NEM is blocked by the subsequent addition of DTT, indicating that potentiation by NEM is mediated by an oxidative event rather than by substitution as such. We find that also pore induction by high (0.5-1.0 mM) concentrations of NEM in the absence of oxidants is completely blocked by reduction with DTT or beta-mercaptoethanol. These results underscore the unexpected importance of oxidative events in pore opening by substituting agents. Since we find that pore opening by Cu(OP)(2) or by high concentrations of NEM is not accompanied by dimerization of the adenine nucleotide translocase, we conclude that the translocase itself is not the target of the pore-inducing oxidative events triggered by Cu(OP)(2) and NEM. (C) 1998 Elsevier Science B.V. All rights reserved.