Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210.
Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210.
Mol Biol Cell. 2020 Jul 15;31(15):1570-1583. doi: 10.1091/mbc.E20-01-0067. Epub 2020 May 20.
Membrane trafficking during cytokinesis is essential for the delivery of membrane lipids and cargoes to the division site. However, the molecular mechanisms are still incompletely understood. In this study, we demonstrate the importance of uncharacterized fission yeast proteins Mso1 and Sec1 in membrane trafficking during cytokinesis. Fission yeast Mso1 shares homology with budding yeast Mso1 and human Mint1, proteins that interact with Sec1/Munc18 family proteins during vesicle fusion. Sec1/Munc18 proteins and their interactors are important regulators of SNARE complex formation during vesicle fusion. The roles of these proteins in vesicle trafficking during cytokinesis have been barely studied. Here, we show that fission yeast Mso1 is also a Sec1-binding protein and Mso1 and Sec1 localize to the division site interdependently during cytokinesis. The loss of Sec1 localization in cells results in a decrease in vesicle fusion and cytokinesis defects such as slow ring constriction, defective ring disassembly, and delayed plasma membrane closure. We also find that Mso1 and Sec1 may have functions independent of the exocyst tethering complex on the plasma membrane at the division site. Together, Mso1 and Sec1 play essential roles in regulating vesicle fusion and cargo delivery at the division site during cytokinesis.
有丝分裂期间的膜运输对于膜脂质和货物向分裂部位的输送至关重要。然而，其分子机制仍不完全清楚。在这项研究中，我们证明了裂殖酵母蛋白 Mso1 和 Sec1 在有丝分裂期间膜运输中的重要性。裂殖酵母 Mso1 与芽殖酵母 Mso1 和人类 Mint1 具有同源性，这些蛋白在囊泡融合过程中与 Sec1/Munc18 家族蛋白相互作用。Sec1/Munc18 蛋白及其相互作用因子是囊泡融合过程中 SNARE 复合物形成的重要调节剂。这些蛋白在有丝分裂期间囊泡运输中的作用几乎没有被研究过。在这里，我们表明裂殖酵母 Mso1 也是 Sec1 的结合蛋白，并且 Mso1 和 Sec1 在有丝分裂期间独立定位于分裂部位。在 细胞中 Sec1 定位的缺失导致囊泡融合减少和有丝分裂缺陷，如环收缩缓慢、环解体缺陷和细胞质膜闭合延迟。我们还发现 Mso1 和 Sec1 可能具有独立于质膜上分裂位点的外核酶停泊复合物的功能。总之，Mso1 和 Sec1 在调节有丝分裂期间分裂部位的囊泡融合和货物运输中发挥着重要作用。
