Roles of the TRAPP-II Complex and the Exocyst in Membrane Deposition during Fission Yeast Cytokinesis.
Roles of the TRAPP-II Complex and the Exocyst in Membrane Deposition during Fission Yeast Cytokinesis.
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DOI：
10.1371/journal.pbio.1002437
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发表时间：
2016-04
期刊：
影响因子：
9.8
通讯作者：
Wu JQ
中科院分区：
文献类型：
--
作者：
Wang N;Lee IJ;Rask G;Wu JQ
与肌动球蛋白收缩环相邻的卵裂沟尖端被认为是胞质分裂过程中通过外囊束缚的小泡插入质膜的主要位点。在这里，我们发现，大多数分泌囊泡提供肌球蛋白-V的线性肌动蛋白电缆在裂变酵母胞质分裂。令人惊讶的是，通过跟踪单个的胞吐和胞吞事件，我们发现，新膜的囊泡沉积到分裂沟相对均匀的收缩环收缩期间，但边缘的分裂沟是内吞作用的主要网站。囊泡与质膜的融合需要囊泡系链。我们的数据表明，运输颗粒蛋白II（TRAPP-II）复合物和Rab11 GTIPYPT 3有助于束缚分泌囊泡或管泡结构沿着分裂沟，而外囊束缚囊泡在分裂面的边缘。我们的结论是，胞吐和TRAPP-II复合物有不同的定位在分裂网站，但都是重要的细胞质分裂过程中的膜扩张和胞吐。两个假定的囊泡系链-外囊和TRAPP-II复合物-在分裂平面上不同地定位，以确保在裂殖酵母裂殖酵母胞质分裂期间沿沿着整个卵裂沟有效的质膜沉积。在每个细胞分裂周期结束时，胞质分裂将母细胞分成两个子细胞。在许多细胞类型中，胞质分裂期间在卵裂沟处需要大量的新质膜。膜扩张是通过胞吐和胞吞的平衡来实现的。细胞质分裂过程中，细胞膜在何处、何时沉积和回收还不清楚。通过高时空分辨率跟踪单个囊泡并使用电子显微镜，我们发现新膜相对均匀地沿着分裂酵母中的分裂沟沉积，而分裂平面的边缘是内吞作用的主要部位。携带新膜的分泌囊泡/隔室主要通过肌球蛋白V马达沿沿着有甲醛核的肌动蛋白电缆递送。令人惊讶的是，我们发现在收缩环收缩之前，细胞分裂部位的胞吐和胞吞作用都增加，并持续到子细胞分离。我们发现，两个假定的囊泡拴系，外囊和TRAPP-II复合物，定位于不同的网站在分裂沟，以促进拴系不同的，但重叠，类分泌囊泡/隔室的胞吐作用和新的膜沉积。
The cleavage-furrow tip adjacent to the actomyosin contractile ring is believed to be the predominant site for plasma-membrane insertion through exocyst-tethered vesicles during cytokinesis. Here we found that most secretory vesicles are delivered by myosin-V on linear actin cables in fission yeast cytokinesis. Surprisingly, by tracking individual exocytic and endocytic events, we found that vesicles with new membrane are deposited to the cleavage furrow relatively evenly during contractile-ring constriction, but the rim of the cleavage furrow is the main site for endocytosis. Fusion of vesicles with the plasma membrane requires vesicle tethers. Our data suggest that the transport particle protein II (TRAPP-II) complex and Rab11 GTPase Ypt3 help to tether secretory vesicles or tubulovesicular structures along the cleavage furrow while the exocyst tethers vesicles at the rim of the division plane. We conclude that the exocyst and TRAPP-II complex have distinct localizations at the division site, but both are important for membrane expansion and exocytosis during cytokinesis. Two putative vesicle tethers—the exocyst and TRAPP-II complexes—localize differently at the division plane to ensure efficient plasma-membrane deposition along the whole cleavage furrow during cytokinesis in the fission yeast Schizosaccharomyces pombe. Cytokinesis partitions a mother cell into two daughter cells at the end of each cell-division cycle. A significant amount of new plasma membrane is needed at the cleavage furrow during cytokinesis in many cell types. Membrane expansion is achieved through the balance of exocytosis and endocytosis. It is poorly understood where and when the membrane is deposited and retrieved during cytokinesis. By tracking individual vesicles with high spatiotemporal resolution and using electron microscopy, we found that new membrane is deposited relatively evenly along the cleavage furrow in fission yeast, while the rim of the division plane is the predominant site for endocytosis. The secretory vesicles/compartments carrying new membrane are mainly delivered along formin-nucleated actin cables by myosin-V motors. Surprisingly, we find that both exocytosis and endocytosis at the division site are ramped up before contractile-ring constriction and last until daughter-cell separation. We discovered that two putative vesicle tethers, the exocyst and TRAPP-II complexes, localize to different sites at the cleavage furrow to promote tethering of different, yet overlapping, classes of secretory vesicles/compartments for exocytosis and new membrane deposition.