Cell Division Laboratory, Temasek Life Sciences Laboratory, Singapore 117604.
J Cell Biol. 2012 Nov 26;199(5):831-47. doi: 10.1083/jcb.201209044.
In many eukaryotes, cytokinesis requires the assembly and constriction of an actomyosin-based contractile ring. Despite the central role of this ring in cytokinesis, the mechanism of F-actin assembly and accumulation in the ring is not fully understood. In this paper, we investigate the mechanism of F-actin assembly during cytokinesis in Schizosaccharomyces pombe using lifeact as a probe to monitor actin dynamics. Previous work has shown that F-actin in the actomyosin ring is assembled de novo at the division site. Surprisingly, we find that a significant fraction of F-actin in the ring was recruited from formin-Cdc12p nucleated long actin cables that were generated at multiple nonmedial locations and incorporated into the ring by a combination of myosin II and myosin V activities. Our results, together with findings in animal cells, suggest that de novo F-actin assembly at the division site and directed transport of F-actin cables assembled elsewhere can contribute to ring assembly.
在许多真核生物中，胞质分裂需要肌动球蛋白收缩环的组装和收缩。尽管该环在胞质分裂中起着核心作用，但环中 F-肌动蛋白的组装和积累的机制尚未完全理解。在本文中，我们使用 Lifeact 作为探针来监测肌动蛋白动力学，研究裂殖酵母中胞质分裂过程中 F-肌动蛋白的组装机制。先前的工作表明，肌动球蛋白环中的 F-肌动蛋白是在分裂部位从头组装的。令人惊讶的是，我们发现环中的很大一部分 F-肌动蛋白是由形成蛋白-Cdc12p 引发的长肌动蛋白纤维募集而来的，这些纤维是在多个非中部位产生的，并通过肌球蛋白 II 和肌球蛋白 V 的活性结合到环中。我们的结果与动物细胞的研究结果一起表明，在分裂部位进行的 F-肌动蛋白的从头组装和在其他地方组装的 F-肌动蛋白纤维的定向运输都可以促进环的组装。
