Selective mitochondrial depletion, apoptosis resistance, and increased mitophagy in human Charcot-Marie-Tooth 2A motor neurons
Selective mitochondrial depletion, apoptosis resistance, and increased mitophagy in human Charcot-Marie-Tooth 2A motor neurons
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DOI：
10.1093/hmg/ddw258
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发表时间：
2016-10-01
影响因子：
3.5
通讯作者：
Corti, Stefania
中科院分区：
文献类型：
--
作者：
Rizzo, Federica;Ronchi, Dario;Corti, Stefania
腓骨肌萎缩症2A（CMT 2A）是由MFN 2突变引起的遗传性周围神经病，MFN 2编码参与线粒体网络稳态的线粒体膜蛋白。由于MFN 2广泛表达，因此选择性运动神经元（MN）参与CMT 2A的原因尚不清楚。为了解决这个问题，我们从CMT 2A患者获得的诱导多能干细胞（iPSC）中产生MN作为体外疾病模型。CMT 2A iPSC衍生的MN（CMT 2A-MN）表现出线粒体含量的整体减少和线粒体定位的改变，而在存活和轴突伸长方面没有显著差异。凋亡执行程序的关键组成部分的RNA测序谱和蛋白质研究（i. e. p53、BAX、半胱天冬酶8、裂解的半胱天冬酶3和抗凋亡标记物Bcl 2）证实CMT 2A-MN比野生型MN更耐凋亡。探索线粒体生物发生和自噬-溶酶体转录调节之间的平衡，我们观察到CMT 2A-MN中自噬通量增加，这与PINK 1，PARK 2，BNIP 3和BECN 1的剪接变体的表达增加有关，BECN 1的剪接变体最近被证明是线粒体自噬去除的触发因素。综上所述，这些数据表明，在表达突变MFN 2的MN中线粒体的显著减少不是生物发生受损的结果，而更可能是线粒体自噬增强的结果。因此，这些途径代表了可能的新的分子治疗靶点，用于开发有效治疗这种疾病。
Charcot-Marie-Tooth 2A (CMT2A) is an inherited peripheral neuropathy caused by mutations in MFN2, which encodes a mitochondrial membrane protein involved in mitochondrial network homeostasis. Because MFN2 is expressed ubiquitously, the reason for selective motor neuron (MN) involvement in CMT2A is unclear. To address this question, we generated MNs from induced pluripotent stem cells (iPSCs) obtained from the patients with CMT2A as an in vitro disease model. CMT2A iPSC-derived MNs (CMT2A-MNs) exhibited a global reduction in mitochondrial content and altered mitochondrial positioning without significant differences in survival and axon elongation. RNA sequencing profiles and protein studies of key components of the apoptotic executioner program (i. e. p53, BAX, caspase 8, cleaved caspase 3, and the anti-apoptotic marker Bcl2) demonstrated that CMT2A-MNs are more resistant to apoptosis than wild-type MNs. Exploring the balance between mitochondrial biogenesis and the regulation of autophagy-lysosome transcription, we observed an increased autophagic flux in CMT2A-MNs that was associated with increased expression of PINK1, PARK2, BNIP3, and a splice variant of BECN1 that was recently demonstrated to be a trigger for mitochondrial autophagic removal. Taken together, these data suggest that the striking reduction in mitochondria in MNs expressing mutant MFN2 is not the result of impaired biogenesis, but more likely the consequence of enhanced mitophagy. Thus, these pathways represent possible novel molecular therapeutic targets for the development of an effective cure for this disease.