Membrane Traffic and Cell Division Lab, Institut Pasteur, UMR3691, CNRS, F-75015, Paris, France.
Sorbonne Université, Collège doctoral, F-75005, Paris, France.
Nat Commun. 2020 Apr 22;11(1):1941. doi: 10.1038/s41467-020-15205-z.
Cytokinesis requires the constriction of ESCRT-III filaments on the side of the midbody, where abscission occurs. After ESCRT recruitment at the midbody, it is not known how the ESCRT-III machinery localizes to the abscission site. To reveal actors involved in abscission, we obtained the proteome of intact, post-abscission midbodies (Flemmingsome) and identified 489 proteins enriched in this organelle. Among these proteins, we further characterized a plasma membrane-to-ESCRT module composed of the transmembrane proteoglycan syndecan-4, ALIX and syntenin, a protein that bridges ESCRT-III/ALIX to syndecans. The three proteins are highly recruited first at the midbody then at the abscission site, and their depletion delays abscission. Mechanistically, direct interactions between ALIX, syntenin and syndecan-4 are essential for proper enrichment of the ESCRT-III machinery at the abscission site, but not at the midbody. We propose that the ESCRT-III machinery must be physically coupled to a membrane protein at the cytokinetic abscission site for efficient scission, uncovering common requirements in cytokinesis, exosome formation and HIV budding.
胞质分裂需要在发生分离的后期胞体侧面收缩 ESCRT-III 纤维。ESCRT 募集到后期胞体后，ESCRT-III 机械装置如何定位到分离位点尚不清楚。为了揭示参与分离的因子，我们获得了完整的、分离后的中期胞体（Flemmingsome）的蛋白质组，并鉴定了 489 种在该细胞器中富集的蛋白质。在这些蛋白质中，我们进一步表征了一个由跨膜蛋白聚糖 syndecan-4、ALIX 和 syntenin 组成的质膜到 ESCRT 模块，该蛋白将 ESCRT-III/ALIX 与 syndecans 桥接。这三种蛋白首先在中期胞体高度募集，然后在分离位点募集，它们的耗竭会延迟分离。从机制上讲，ALIX、syntenin 和 syndecan-4 之间的直接相互作用对于 ESCRT-III 机械装置在分离位点的正确富集是必需的，但在中期胞体不是必需的。我们提出，ESCRT-III 机械装置必须与有丝分裂分离位点的膜蛋白物理偶联，以实现有效的分裂，这揭示了胞质分裂、外体形成和 HIV 出芽的共同要求。
