Silva Ana M, Osório Daniel S, Pereira Antonio J, Maiato Helder, Pinto Inês Mendes, Rubinstein Boris, Gassmann Reto, Telley Ivo Andreas, Carvalho Ana Xavier
Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.
Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.
J Cell Biol. 2016 Dec 19;215(6):789-799. doi: 10.1083/jcb.201605080. Epub 2016 Dec 13.
Cytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting rings in Caenorhabditis elegans embryos. Laser cutting causes rings to snap open. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms and is repaired by recruitment of new material in an actin polymerization-dependent manner. An open ring is able to constrict, and rings repair from successive cuts. After gap repair, an increase in constriction velocity allows cytokinesis to complete at the same time as controls. Our analysis demonstrates that tension in the ring increases while net cortical tension at the site of ingression decreases throughout constriction and suggests that cytokinesis is accomplished by contractile modules that assemble and contract autonomously, enabling local repair of the actomyosin network. Consequently, cytokinesis is a highly robust process impervious to discontinuities in contractile ring structure.
动物细胞中的胞质分裂需要肌动球蛋白收缩环的收缩，但其结构和机制仍知之甚少。我们利用激光显微手术来探究秀丽隐杆线虫胚胎中收缩环的生物物理特性。激光切割会使环突然打开。然而，环的拓扑结构并非解体，而是恢复并继续收缩。切割后会形成一个有限的间隙，并通过以肌动蛋白聚合依赖的方式募集新材料来修复。开放的环能够收缩，并且环能从连续的切割中修复。间隙修复后，收缩速度的增加使胞质分裂能够与对照同时完成。我们的分析表明，在整个收缩过程中，环中的张力增加，而侵入部位的净皮质张力降低，这表明胞质分裂是由能够自主组装和收缩的收缩模块完成的，从而实现肌动球蛋白网络的局部修复。因此，胞质分裂是一个高度稳健的过程，不受收缩环结构不连续性的影响。
