Rauen Ursula, Petrat Frank, Sustmann Reiner, de Groot Herbert
Institut für Physiologische Chemie, Universitätsklinikum, Hufelandstr. 55, D-45122 Essen, Germany.
J Hepatol. 2004 Apr;40(4):607-15. doi: 10.1016/j.jhep.2003.12.021.
BACKGROUND/AIMS: We previously described that the cold-induced apoptosis of cultured hepatocytes and liver endothelial cells is mediated by an increase in the cellular chelatable iron pool-in the absence of any increase in O(2)(.-)/H(2)O(2) formation. As this is an unusual mechanism, we here set out to assess whether an increase in cellular chelatable iron per se is sufficient to trigger cell injury/apoptosis.
Cultured rat hepatocytes were acutely loaded with iron using the membrane-permeable complex Fe(III)/8-hydroxyquinoline and incubated under otherwise 'physiological' conditions.
Incubation with Fe(III)/8-hydroxyquinoline (15 microM/30 microM) increased the cellular chelatable iron and induced strong hepatocellular injury with morphological features of apoptosis, but also of necrosis. The iron-induced cell injury was oxygen-dependent, and although it was not inhibitable by extracellular catalase, it was strongly inhibited by the novel membrane-permeable catalase mimic TAA-1/Fe. The experimentally induced increase in cellular chelatable iron triggered a mitochondrial permeability transition (MPT) as assessed using double-staining with calcein and tetramethylrhodamine methyl ester. The MPT inhibitor cyclosporine A partially and the well-known inhibitor combination trifluoperazine+fructose completely inhibited the iron-induced cell injury/apoptosis.
These results show that iron per se can induce cell injury/apoptosis and that this injury is mediated via an MPT.
背景/目的：我们之前描述过，在培养的肝细胞和肝内皮细胞中，冷诱导的细胞凋亡是由细胞可螯合铁池增加介导的，而此时超氧阴离子/过氧化氢的生成并无增加。由于这是一种不寻常的机制，我们在此着手评估细胞可螯合铁本身的增加是否足以引发细胞损伤/凋亡。
使用膜通透性复合物Fe(III)/8-羟基喹啉对培养的大鼠肝细胞进行急性铁加载，并在其他“生理”条件下孵育。
用Fe(III)/8-羟基喹啉（15微摩尔/30微摩尔）孵育可增加细胞可螯合铁，并诱导强烈的肝细胞损伤，具有凋亡的形态学特征，但也有坏死的特征。铁诱导的细胞损伤是氧依赖性的，虽然它不能被细胞外过氧化氢酶抑制，但可被新型膜通透性过氧化氢酶模拟物TAA-1/Fe强烈抑制。使用钙黄绿素和四甲基罗丹明甲酯双重染色评估，实验诱导的细胞可螯合铁增加引发了线粒体通透性转换（MPT）。MPT抑制剂环孢素A部分抑制，而众所周知的抑制剂组合三氟拉嗪+果糖完全抑制铁诱导的细胞损伤/凋亡。
这些结果表明，铁本身可诱导细胞损伤/凋亡，且这种损伤是通过MPT介导的。
