OPA1 突变所致视神经萎缩中的线粒体自噬失调与线粒体组织紊乱
Dysregulated mitophagy and mitochondrial organization in optic atrophy due to OPA1 mutations.
作者信息
Liao Chunyan, Ashley Neil, Diot Alan, Morten Karl, Phadwal Kanchan, Williams Andrew, Fearnley Ian, Rosser Lyndon, Lowndes Jo, Fratter Carl, Ferguson David J P, Vay Laura, Quaghebeur Gerardine, Moroni Isabella, Bianchi Stefania, Lamperti Costanza, Downes Susan M, Sitarz Kamil S, Flannery Padraig J, Carver Janet, Dombi Eszter, East Daniel, Laura Matilde, Reilly Mary M, Mortiboys Heather, Prevo Remko, Campanella Michelangelo, Daniels Matthew J, Zeviani Massimo, Yu-Wai-Man Patrick, Simon Anna Katharina, Votruba Marcela, Poulton Joanna
机构信息
Author affiliations are provided at the end of the article.
出版信息
Neurology. 2017 Jan 10;88(2):131-142. doi: 10.1212/WNL.0000000000003491. Epub 2016 Dec 14.
OBJECTIVE
To investigate mitophagy in 5 patients with severe dominantly inherited optic atrophy (DOA), caused by depletion of OPA1 (a protein that is essential for mitochondrial fusion), compared with healthy controls.
METHODS
Patients with severe DOA (DOA plus) had peripheral neuropathy, cognitive regression, and epilepsy in addition to loss of vision. We quantified mitophagy in dermal fibroblasts, using 2 high throughput imaging systems, by visualizing colocalization of mitochondrial fragments with engulfing autophagosomes.
RESULTS
Fibroblasts from 3 biallelic OPA1(-/-) patients with severe DOA had increased mitochondrial fragmentation and mitochondrial DNA (mtDNA)-depleted cells due to decreased levels of OPA1 protein. Similarly, in siRNA-treated control fibroblasts, profound OPA1 knockdown caused mitochondrial fragmentation, loss of mtDNA, impaired mitochondrial function, and mitochondrial mislocalization. Compared to controls, basal mitophagy (abundance of autophagosomes colocalizing with mitochondria) was increased in (1) biallelic patients, (2) monoallelic patients with DOA plus, and (3) OPA1 siRNA-treated control cultures. Mitophagic flux was also increased. Genetic knockdown of the mitophagy protein ATG7 confirmed this by eliminating differences between patient and control fibroblasts.
CONCLUSIONS
We demonstrated increased mitophagy and excessive mitochondrial fragmentation in primary human cultures associated with DOA plus due to biallelic OPA1 mutations. We previously found that increased mitophagy (mitochondrial recycling) was associated with visual loss in another mitochondrial optic neuropathy, Leber hereditary optic neuropathy (LHON). Combined with our LHON findings, this implicates excessive mitochondrial fragmentation, dysregulated mitophagy, and impaired response to energetic stress in the pathogenesis of mitochondrial optic neuropathies, potentially linked with mitochondrial mislocalization and mtDNA depletion.
目的
研究5例由OPA1（线粒体融合所必需的一种蛋白质）缺失导致的严重显性遗传性视神经萎缩（DOA）患者的线粒体自噬，并与健康对照进行比较。
方法
严重DOA患者（DOA plus）除视力丧失外，还伴有周围神经病变、认知衰退和癫痫。我们使用2种高通量成像系统，通过观察线粒体片段与吞噬自噬体的共定位，对皮肤成纤维细胞中的线粒体自噬进行定量分析。
结果
3例双等位基因OPA1(-/-)的严重DOA患者的成纤维细胞，由于OPA1蛋白水平降低，线粒体碎片化增加，线粒体DNA（mtDNA）缺失细胞增多。同样，在经小干扰RNA（siRNA）处理的对照成纤维细胞中，OPA1的深度敲低导致线粒体碎片化、mtDNA丢失、线粒体功能受损以及线粒体定位错误。与对照组相比，基础线粒体自噬（与线粒体共定位的自噬体丰度）在以下情况中增加：（1）双等位基因患者；（2）伴有DOA plus的单等位基因患者；（3）经OPA1 siRNA处理的对照培养物。线粒体自噬通量也增加。线粒体自噬蛋白ATG7的基因敲低通过消除患者和对照成纤维细胞之间的差异证实了这一点。
结论
我们证明，与双等位基因OPA1突变导致的DOA plus相关的原代人培养物中，线粒体自噬增加，线粒体过度碎片化。我们之前发现，线粒体自噬增加（线粒体循环利用）与另一种线粒体视神经病变——Leber遗传性视神经病变（LHON）的视力丧失有关。结合我们在LHON中的发现，这表明线粒体过度碎片化、线粒体自噬失调以及对能量应激的反应受损在线粒体视神经病变的发病机制中起作用，可能与线粒体定位错误和mtDNA缺失有关。
Zotero 插件