Mitofusin 2 is necessary for transport of axonal mitochondria and interacts with the Miro/Milton complex.
Mitofusin 2 is necessary for transport of axonal mitochondria and interacts with the Miro/Milton complex.
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DOI：
10.1523/jneurosci.6248-09.2010
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发表时间：
2010-03-24
期刊：
影响因子：
--
通讯作者：
Baloh RH
中科院分区：
文献类型：
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作者：
Misko A;Jiang S;Wegorzewska I;Milbrandt J;Baloh RH
Mitofusins(Mfn1和Mfn2)是参与调节线粒体动力学的线粒体膜外膜蛋白。Mfn2基因突变导致2A型Charcot-Marie-Tooth病(CMT)，这是一种以长轴突变性为特征的遗传性疾病，但这种组织选择性的性质尚不清楚。在这里，我们提出的证据表明，Mfn2直接参与轴突线粒体的运输，并与其在线粒体融合中的作用不同。对Mfn2基因敲除小鼠培养的神经元或表达Mfn2疾病突变体的神经元的实时成像显示，轴突线粒体暂停的时间更长，顺行和逆行运动更慢，表明与基于微管的运输系统的附着发生了变化。此外，Mfn2的破坏选择性地改变了线粒体的运动，使其他细胞器的运输保持不变。重要的是，Mfn1和Mfn2都与哺乳动物Miro(Miro1/Miro2)和Milton(OIP106/GRIF1)蛋白相互作用，Mfn1和Mfn2都是连接线粒体和动蛋白马达的分子复合体的成员。在培养的神经元中敲除Miro2产生了与Mfn2丢失相同的运输缺陷，这表明这两种蛋白必须存在于外膜以介导轴突线粒体的运输。相反，通过敲除线粒体内膜蛋白OPA1而破坏线粒体融合对线粒体运动性没有影响，表明融合丧失本身并不改变线粒体的运输。这些实验确定了丝裂原蛋白在直接调节线粒体运输中的作用，并为了解CMT2A中轴突变性和显性视神经萎缩的细胞类型特异性和分子机制提供了重要的见解。
Mitofusins (Mfn1 and Mfn2) are outer mitochondrial membrane proteins involved in regulating mitochondrial dynamics. Mutations in Mfn2 cause Charcot-Marie-Tooth disease (CMT) type 2A, an inherited disease characterized by degeneration of long peripheral axons, but the nature of this tissue selectivity remains unknown. Here we present evidence that Mfn2 is directly involved in and required for axonal mitochondrial transport, distinct from its role in mitochondrial fusion. Live imaging of neurons cultured from Mfn2 knockout mice, or neurons expressing Mfn2 disease mutants, show that axonal mitochondria spend more time paused and undergo slower anterograde and retrograde movements, indicating an alteration in attachment to microtubule based transport systems. Furthermore, Mfn2 disruption altered mitochondrial movement selectively, leaving transport of other organelles intact. Importantly, both Mfn1 and Mfn2 interact with mammalian Miro (Miro1/Miro2) and Milton (OIP106/GRIF1) proteins, members of the molecular complex that link mitochondria to kinesin motors. Knockdown of Miro2 in cultured neurons produced transport deficits identical to loss of Mfn2, indicating that both proteins must be present at the outer membrane to mediate axonal mitochondrial transport. In contrast, disruption of mitochondrial fusion via knockdown of the inner mitochondrial membrane protein Opa1 had no effect on mitochondrial motility, indicating that loss of fusion does not inherently alter mitochondrial transport. These experiments identify a role for mitofusins in directly regulating mitochondrial transport, and offer important insight into the cell type specificity and molecular mechanisms of axonal degeneration in CMT2A and dominant optic atrophy.