Loss of OPA1 perturbates the mitochondrial inner membrane structure and integrity, leading to cytochrome c release and apoptosis
Loss of OPA1 perturbates the mitochondrial inner membrane structure and integrity, leading to cytochrome c release and apoptosis
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DOI：
10.1074/jbc.c200677200
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发表时间：
2003-03-07
影响因子：
4.8
通讯作者：
Lenaers, G
中科院分区：
文献类型：
--
作者：
Olichon, A;Baricault, L;Lenaers, G
OPA1编码一种与发动蛋白相关的大分子GTP酶，它锚定在线粒体嵴内膜上，面向膜间隙。OPA1单倍体不足是最常见的常染色体显性视神经萎缩（ADOA，MIM165500）的病因，这是一种由视网膜神经节细胞变性和视神经萎缩导致的神经病变。在此我们表明，利用特异性小干扰RNA（siRNA）在HeLa细胞中下调OPA1会导致线粒体网络碎片化，同时线粒体膜电位消散以及嵴严重紊乱。这些事件之后会出现细胞色素c释放以及半胱天冬酶依赖性的凋亡核事件。同样，在NIH - OVCAR - 3细胞中，OPA1 siRNA诱导线粒体碎片化和细胞凋亡，后者可被Bcl2过表达所抑制。这些结果表明，OPA1是线粒体内膜的主要组织者，嵴的完整性维持依赖于此。由于OPA1缺失会使细胞在没有任何其他刺激的情况下发生细胞凋亡，我们提出OPA1参与细胞色素c的隔离，并且可能是线粒体凋亡效应因子的一个靶点。我们的结果还表明，异常细胞凋亡是导致ADOA患者视网膜神经节细胞变性的一种可能的病理生理过程。
OPA1 encodes a large GTPase related to dynamins, anchored to the mitochondrial cristae inner membrane, facing the intermembrane space. OPA1 haplo-insufficiency is responsible for the most common form of autosomal dominant optic atrophy (ADOA, MIM165500), a neuropathy resulting from degeneration of the retinal ganglion cells and optic nerve atrophy. Here we show that down-regulation of OPA1 in HeLa cells using specific small interfering RNA (siRNA) leads to fragmentation of the mitochondrial network concomitantly to the dissipation of the mitochondrial membrane potential and to a drastic disorganization of the cristae. These events are followed by cytochrome c release and caspase-dependent apoptotic nuclear events. Similarly, in NIHOVCAR-3 cells, the OPA1 siRNA induces mitochondrial fragmentation and apoptosis, the latter being inhibited by Bcl2 overexpression. These results suggest that OPA1 is a major organizer of the mitochondrial inner membrane from which the maintenance of the cristae integrity depends. As loss of OPA1 commits cells to apoptosis without any other stimulus, we propose that OPA1 is involved in the cytochrome c sequestration and might be a target for mitochondrial apoptotic effectors. Our results also suggest that abnormal apoptosis is a possible pathophysiological process leading to the retinal ganglion cells degeneration in ADOA patients.