Mandato Craig A, Bement William M
Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Curr Biol. 2003 Jul 1;13(13):1096-105. doi: 10.1016/s0960-9822(03)00420-2.
Interactions between microtubules and actin filaments (F-actin) are critical for cellular motility processes ranging from directed cell locomotion to cytokinesis. However, the cellular bases of these interactions remain poorly understood. We have analyzed the role of microtubules in generation of a contractile array comprised of F-actin and myosin-2 that forms around wounds made in Xenopus oocytes.
After wounding, microtubules are transported to the wound edge in association with F-actin that is itself recruited to wound borders via actomyosin-powered cortical flow. This transport generates sufficient force to buckle and break microtubules at the wound edge. Transport is complemented by local microtubule assembly around wound borders. The region of microtubule breakage and assembly coincides with a zone of actin assembly, and perturbation of the microtubule cytoskeleton disrupts this zone as well as local recruitment of the Arp2/3 complex and myosin-2.
The results reveal transport of microtubules in association with F-actin that is pulled to wound borders via actomyosin-based contraction. Microtubules, in turn, focus zones of actin assembly and myosin-2 recruitment at the wound border. Thus, wounding triggers the formation of a spatially coordinated feedback loop in which transport and assembly of microtubules maintains actin and myosin-2 in close proximity to the closing contractile array. These results are surprisingly reminiscent of recent findings in locomoting cells, suggesting that similar feedback interactions may be generally employed in a variety of fundamental cell motility processes.
微管与肌动蛋白丝（F-肌动蛋白）之间的相互作用对于从定向细胞运动到胞质分裂等细胞运动过程至关重要。然而，这些相互作用的细胞基础仍知之甚少。我们分析了微管在由F-肌动蛋白和肌球蛋白-2组成的收缩阵列生成中的作用，该收缩阵列在非洲爪蟾卵母细胞的伤口周围形成。
受伤后，微管与F-肌动蛋白一起被运输到伤口边缘，而F-肌动蛋白本身通过肌动球蛋白驱动的皮层流动被招募到伤口边缘。这种运输产生足够的力使微管在伤口边缘弯曲和断裂。运输过程由伤口边缘周围的局部微管组装补充。微管断裂和组装的区域与肌动蛋白组装区域重合，微管细胞骨架的扰动会破坏该区域以及Arp2/3复合物和肌球蛋白-2的局部招募。
结果揭示了微管与F-肌动蛋白的运输，F-肌动蛋白通过基于肌动球蛋白的收缩被拉到伤口边缘。反过来，微管在伤口边缘聚焦肌动蛋白组装和肌球蛋白-2招募区域。因此，受伤触发了空间协调反馈回路的形成，其中微管的运输和组装使肌动蛋白和肌球蛋白-2保持在靠近闭合收缩阵列的位置。这些结果惊人地让人想起最近在运动细胞中的发现，表明类似的反馈相互作用可能普遍用于各种基本的细胞运动过程。
