Kinesin-3 and dynein mediate microtubule-dependent co-transport of mRNPs and endosomes
Kinesin-3 and dynein mediate microtubule-dependent co-transport of mRNPs and endosomes
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DOI：
10.1242/jcs.101212
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发表时间：
2012-06-01
影响因子：
4
通讯作者：
Feldbruegge, Michael
中科院分区：
文献类型：
--
作者：
Baumann, Sebastian;Pohlmann, Thomas;Feldbruegge, Michael
mRNA的长距离运输在真核生物中决定极性是重要的。分子马达沿着沿着微管穿梭含有RNA结合蛋白和相关因子的大核糖核蛋白复合物（mRNP）。然而，包括分子马达的相互作用和与膜运输的潜在联系在内的精确机制仍然难以捉摸。在这里，我们解决了电机组成的mRNP含有RNA结合蛋白Rrm 4的病原体玉米黑粉菌。潜在的运输过程决定了感染性丝状体的极性轴。加端定向Kin 3，驱动蛋白-3型电机，介导mRNP的顺行运输，也存在于逆行移动的运输单位。断裂动力蛋白Dyn 1-Dyn 2在mRNP的逆行运动中起作用。正末端导向的常规驱动蛋白Kin 1通过将负末端导向的动力蛋白转运回正末端而间接参与。重要的是，我们还证明了含有Rrm 4的mRNP与穿梭内体上的t-SNARE Yup 1共定位，并且功能性内体对于mRNP运动是必不可少的。Kin 3的丢失或其脂质结合普列克底物蛋白同源结构域的去除废除了Rrm 4依赖性运动，而不阻止Rrm 4和Yup 1阳性内体的共定位。总之，我们发现了mRNP沿沿着微管穿梭所需的马达组合。此外，内体和mRNP的密切相关的共转运表明囊泡搭便车作为mRNP转运的模式。
Long-distance transport of mRNAs is important in determining polarity in eukaryotes. Molecular motors shuttle large ribonucleoprotein complexes (mRNPs) containing RNA-binding proteins and associated factors along microtubules. However, precise mechanisms including the interplay of molecular motors and a potential connection to membrane trafficking remain elusive. Here, we solve the motor composition of transported mRNPs containing the RNA-binding protein Rrm4 of the pathogen Ustilago maydis. The underlying transport process determines the axis of polarity in infectious filaments. Plus-end-directed Kin3, a kinesin-3 type motor, mediates anterograde transport of mRNPs and is also present in transport units moving retrogradely. Split dynein Dyn1-Dyn2 functions in retrograde movement of mRNPs. Plus-end-directed conventional kinesin Kin1 is indirectly involved by transporting minus-end-directed dynein back to plus ends. Importantly, we additionally demonstrate that Rrm4-containing mRNPs colocalise with the t-SNARE Yup1 on shuttling endosomes and that functional endosomes are essential for mRNP movement. Either loss of Kin3 or removal of its lipid-binding pleckstrin-homology domain abolishes Rrm4-dependent movement without preventing colocalisation of Rrm4 and Yup1-positive endosomes. In summary, we uncovered the combination of motors required for mRNP shuttling along microtubules. Furthermore, intimately linked co-transport of endosomes and mRNPs suggests vesicle hitchhiking as mode of mRNP transport.