Weis M, Kass G E, Orrenius S, Moldéus P
Department of Toxicology, Karolinska Institutet, Stockholm, Sweden.
J Biol Chem. 1992 Jan 15;267(2):804-9.
The mechanism of N-acetyl-p-benzoquinone imine (NAPQI)-induced release of Ca2+ from rat liver mitochondria was investigated. The addition of NAPQI or 3,5-Me2-NAPQI (a dimethylated analogue of NAPQI with only oxidizing properties) to mitochondria resulted in the rapid and extensive oxidation of NADH and NADPH. High-performance liquid chromatographic analysis of mitochondrial pyridine nucleotides revealed that the formation of NAD+ and NADP+ was followed by a time-dependent net loss of total pyridine nucleotides as a result of their hydrolysis, with the formation of nicotinamide. Preincubation of the mitochondria with cyclosporin A completely prevented the quinone imine-stimulated release of sequestered Ca2+ from mitochondria. Cyclosporin A did not affect the ability of NAPQI or 3,5-Me2-NAPQI to oxidize NAD(P)H but prevented the quinone imine-induced hydrolysis of the pyridine nucleotides. Although there was no detectable change in total protein-bound ADP-ribose content during quinone imine-induced Ca2+ release from mitochondria, meta-iodobenzylguanidine, a competitive inhibitor of protein mono(ADP-ribosylation), prevented Ca2+ release by NAPQI and 3,5-Me2-NAPQI; meta-iodobenzylguanidine did not inhibit the quinone imine-induced NAD(P)H oxidation and only partially blocked hydrolysis of the oxidized pyridine nucleotides. It is concluded that NAPQI causes the oxidation of mitochondrial NADH and NADPH, and stimulates Ca2+ release as a result of the further hydrolysis of the oxidized pyridine nucleotides and protein mono(ADP-ribosylation).
研究了N-乙酰对苯醌亚胺（NAPQI）诱导大鼠肝线粒体释放Ca2+的机制。向线粒体中添加NAPQI或3,5-二甲基-NAPQI（NAPQI的一种仅具有氧化特性的二甲基化类似物）会导致NADH和NADPH迅速且大量氧化。对线粒体吡啶核苷酸进行高效液相色谱分析表明，NAD+和NADP+形成后，由于其水解生成烟酰胺，总吡啶核苷酸会随时间出现净损失。用环孢素A预孵育线粒体可完全阻止醌亚胺刺激线粒体中储存的Ca2+释放。环孢素A不影响NAPQI或3,5-二甲基-NAPQI氧化NAD(P)H的能力，但可阻止醌亚胺诱导的吡啶核苷酸水解。尽管在醌亚胺诱导线粒体释放Ca2+过程中，总蛋白结合的ADP-核糖含量没有可检测到的变化，但蛋白单（ADP-核糖基化）的竞争性抑制剂间碘苄胍可阻止NAPQI和3,5-二甲基-NAPQI诱导的Ca2+释放；间碘苄胍不抑制醌亚胺诱导的NAD(P)H氧化，仅部分阻断氧化吡啶核苷酸的水解。得出的结论是，NAPQI导致线粒体NADH和NADPH氧化，并由于氧化吡啶核苷酸的进一步水解和蛋白单（ADP-核糖基化）而刺激Ca2+释放。
