Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells.
Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells.
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DOI：
10.1038/ncomms11814
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发表时间：
2016-06-02
影响因子：
16.6
通讯作者：
Steinberg G
中科院分区：
文献类型：
--
作者：
Lin C;Schuster M;Guimaraes SC;Ashwin P;Schrader M;Metz J;Hacker C;Gurr SJ;Steinberg G
过氧化物酶体（PO）和脂滴（LD）的均匀分布对于它们在脂质和活性氧体内平衡中的作用至关重要。如何实现均匀分布仍然是难以捉摸的，但扩散运动和定向运动可能发挥作用。在这里，我们表明，在真菌玉米黑粉菌中，95%的PO和LD进行扩散运动。这些运动需要ATP，并涉及双向早期内体运动，表明微管相关的膜运输增强细胞器的扩散。当早期内体转运被取消时，PO和LD缓慢地向生长的细胞末端漂移。这种向极漂移是由肌球蛋白-5将分泌物顺行运送到细胞尖端所促进的。模拟表明，基于微管的定向运输和主动扩散支持分布，流动性和混合的PO。在哺乳动物COS-7细胞中，微管和F-actin也相互抵消以分配PO。这突出了在真核生物中细胞器定位中细胞骨架力的重要性。 真核细胞器的定位机制仍然难以捉摸。在这里，Lin等人使用成像和数学模型表明，基于微管的运输和主动扩散以及基于肌动蛋白的极性漂移共同作用，以促进过氧化物酶体在丝状真菌中的均匀分布。
Even distribution of peroxisomes (POs) and lipid droplets (LDs) is critical to their role in lipid and reactive oxygen species homeostasis. How even distribution is achieved remains elusive, but diffusive motion and directed motility may play a role. Here we show that in the fungus Ustilago maydis ∼95% of POs and LDs undergo diffusive motions. These movements require ATP and involve bidirectional early endosome motility, indicating that microtubule-associated membrane trafficking enhances diffusion of organelles. When early endosome transport is abolished, POs and LDs drift slowly towards the growing cell end. This pole-ward drift is facilitated by anterograde delivery of secretory cargo to the cell tip by myosin-5. Modelling reveals that microtubule-based directed transport and active diffusion support distribution, mobility and mixing of POs. In mammalian COS-7 cells, microtubules and F-actin also counteract each other to distribute POs. This highlights the importance of opposing cytoskeletal forces in organelle positioning in eukaryotes. The mechanisms underlying the positioning of eukaryotic organelles remain elusive. Here Lin et al. use imaging and a mathematical model to show that microtubule-based transport and active diffusion and actin-based polar drift act together to facilitate even distribution of peroxisomes in filamentous fungi.