Mutant huntingtin directly increases susceptibility of mitochondria to the calcium-induced permeability transition and cytochrome c release
Mutant huntingtin directly increases susceptibility of mitochondria to the calcium-induced permeability transition and cytochrome c release
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DOI：
10.1093/hmg/ddh162
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发表时间：
2004-07-15
影响因子：
3.5
通讯作者：
Lesort, M
中科院分区：
文献类型：
--
作者：
Choo, YS;Johnson, GVW;Lesort, M
亨廷顿氏病（HD）是由亨廷顿蛋白中异常扩增的多聚谷氨酰胺延伸引发的，赋予该蛋白一种新的性质，导致纹状体神经元的丧失。线粒体功能缺陷与HD的发病机制有关。在这里，我们已经研究了突变亨廷顿蛋白可能直接相互作用的peptide和影响其功能的假设。在人类神经母细胞瘤细胞和克隆纹状体细胞建立HDH（Q7）（野生型）和HDH（Q111）（突变）纯合子小鼠基因敲入胚胎，亨廷顿蛋白存在于纯化的线粒体组分。线粒体和有限的胰蛋白酶消化的细胞器的亚分级证明，亨廷顿蛋白与外线粒体膜。我们进一步证明，重组截短突变亨廷顿蛋白，而不是野生型，直接诱导线粒体通透性转换（MPT）孔开放在离体小鼠肝线粒体，环孢菌素A（CSA）和ATP完全阻止的效果。重要的是，突变亨廷顿蛋白显着降低了触发MPT孔开放所需的Ca2+阈值。我们发现从基因敲入HD小鼠模型中分离的肝脏线粒体对钙诱导的MPT的敏感性也有类似的增加。突变亨廷顿蛋白诱导的MPT孔开放伴随着细胞色素c的显着释放，CSA完全抑制的效果。这些研究结果表明，特定MPT抑制剂的发展可能是一个有趣的治疗途径，以延迟发病的HD。
Huntington's disease (HD) is initiated by an abnormally expanded polyglutamine stretch in the huntingtin protein, conferring a novel property on the protein that leads to the loss of striatal neurons. Defects in mitochondrial function have been implicated in the pathogenesis of HD. Here, we have examined the hypothesis that the mutant huntingtin protein may directly interact with the mitochondrion and affect its function. In human neuroblastoma cells and clonal striatal cells established from Hdh(Q7) (wild-type) and Hdh(Q111) (mutant) homozygote mouse knock-in embryos, huntingtin was present in a purified mitochondrial fraction. Subfractionation of the mitochondria and limited trypsin digestion of the organelle demonstrated that huntingtin was associated with the outer mitochondrial membrane. We further demonstrated that a recombinant truncated mutant huntingtin protein, but not a wild-type, directly induced mitochondrial permeability transition (MPT) pore opening in isolated mouse liver mitochondria, an effect that was prevented completely by cyclosporin A (CSA) and ATP. Importantly, the mutant huntingtin protein significantly decreased the Ca2+ threshold necessary to trigger MPT pore opening. We found a similar increased susceptibility to the calcium-induced MPT in liver mitochondria isolated from a knock-in HD mouse model. The mutant huntingtin protein-induced MPT pore opening was accompanied by a significant release of cytochrome c, an effect completely inhibited by CSA. These findings suggest that the development of specific MPT inhibitors may be an interesting therapeutic avenue to delay the onset of HD.