Evidence that myosin activity opposes microtubule-based axonal transport of mitochondria.
Evidence that myosin activity opposes microtubule-based axonal transport of mitochondria.
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DOI：
10.1523/jneurosci.1621-10.2010
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发表时间：
2010-06-30
期刊：
影响因子：
--
通讯作者：
Hollenbeck PJ
中科院分区：
文献类型：
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作者：
Pathak D;Sepp KJ;Hollenbeck PJ
神经元使用跳跃、双向运动和静止对接的组合来运输和定位线粒体。轴突线粒体利用驱动蛋白和动力蛋白马达沿沿着运动，但肌动蛋白和肌球蛋白在其运动中也起着不明确的作用。为了确定这一作用，我们使用RNA干扰来消耗培养的果蝇神经元中的特定肌球蛋白马达，并量化对线粒体运动的影响。我们生产了表达C. elegans RNA转运蛋白SID-1在神经元中的表达，以增加RNAi在原代培养物中的功效。与不表达这种转运蛋白的神经元相比，这些神经元表现出显著增加的RNAi介导的基因表达敲低。使用这个系统，我们观察到一个显着增加线粒体转运后肌球蛋白V耗尽。线粒体的平均速度和占空比增加在顺行和逆行方向，和包含在长期运行的线粒体流量的分数几乎翻了一番顺行运动。肌球蛋白VI耗尽增加了相同的运动参数，但选择性逆行运动，而肌球蛋白II耗尽没有产生表型。肌球蛋白V耗竭的另一个影响是线粒体长度增加。这些数据表明，肌球蛋白V和VI在调节MT为基础的线粒体运动中发挥相关但不同的作用：它们反对，而不是补充长期的MT为基础的运动，也许有利于细胞器对接。
Neurons transport and position mitochondria using a combination of saltatory, bidirectional movements and stationary docking. Axonal mitochondria move along microtubules (MTs) using kinesin and dynein motors, but actin and myosin also play a poorly-defined role in their traffic. To ascertain this role, we have used RNA interference to deplete specific myosin motors in cultured Drosophila neurons and quantified the effects on mitochondrial motility. We produced a fly strain expressing the C. elegans RNA transporter SID-1 in neurons to increase the efficacy of RNAi in primary cultures. These neurons exhibited significantly increased RNAi-mediated knockdown of gene expression compared to neurons not expressing this transporter. Using this system, we observed a significant increase in mitochondrial transport upon myosin V depletion. Mitochondrial mean velocity and duty cycle were augmented in both anterograde and retrograde directions, and the fraction of mitochondrial flux contained in long runs almost doubled for anterograde movement. Myosin VI depletion increased the same movement parameters, but was selective for retrograde movement, while myosin II depletion produced no phenotype. An additional effect of myosin V depletion was an increase in mitochondrial length. These data indicate that myosin V and VI play related but distinct roles in regulating MT-based mitochondrial movement: they oppose, rather than complement protracted MT-based movements and perhaps facilitate organelle docking.