Healing of incisional wounds in the embryonic chick wing bud: Characterization of the actin purse-string and demonstration of a requirement for Rho activation
Healing of incisional wounds in the embryonic chick wing bud: Characterization of the actin purse-string and demonstration of a requirement for Rho activation
复制标题
DOI：
10.1083/jcb.135.4.1097
复制
发表时间：
1996-11-01
影响因子：
7.8
通讯作者：
Martin, P
中科院分区：
文献类型：
--
作者：
Brock, J;Midwinter, K;Martin, P
鸡胚的皮肤小伤口不像成年动物的皮肤伤口那样通过伤口边缘细胞的片状伪足爬行来愈合，而是通过在表皮细胞前排迅速组装的肌动蛋白收缩束来愈合（Martin, P., 和J. Lewis. 1992.《自然（伦敦）》360:179 - 183）。为了观察肌动蛋白收缩束组装的早期过程并描述收缩机制的其他细胞骨架成分，我们对鸡翅背部的切口或划伤伤口的愈合进行了研究；这些伤口只需几秒钟就能造成，并且在大约6小时内愈合。上皮的愈合依赖于收缩束收缩以及上皮切割边缘之间间隙的拉链式闭合的共同作用。共聚焦激光扫描显微镜研究表明，在受伤约2分钟内，肌动蛋白最初在表皮基底层的伤口边缘排列成索状。与肌动蛋白索组装同时，我们看到钙黏蛋白在伤口边缘定位成簇，推测这标志着相邻细胞中索的片段通过黏附连接相连的部位。几分钟后，我们还看到肌球蛋白II在伤口边缘定位，如果肌球蛋白被招募到索中以产生伤口愈合的收缩力，这是符合预期的。在受伤时，伤口边缘的细胞会暂时变得渗漏，这使我们能够向它们加载试剂来阻断两种小GTP酶（Rho和Rac）的功能，最近已表明这两种酶在组织培养细胞中肌动蛋白细胞骨架的重组中起关键作用（Hall, A. 1994.《细胞生物学年度评论》10:31 - 54）。用C3转移酶（一种使内源性Rho失活的细菌外酶）加载伤口边缘的表皮细胞，会阻止肌动蛋白索的组装并导致愈合失败。用N17rac（一种显性抑制性突变Rac蛋白）则没有观察到这种效应。这些发现支持了这样一种观点，即在这个系统中，肌动蛋白索对于愈合是必需的——无论是收缩束收缩还是拉链式闭合——并且Rho对于肌动蛋白索的形成是必需的。
Small skin wounds in the chick embryo do not heal by lamellipodial crawling of cells at the wound edge as a skin wound does in the adult, but rather by contraction of an actin purse-string that rapidly assembles in the front row of epidermal cells (Martin, P., and J. Lewis. 1992. Nature (Lond.). 360:179-183). To observe the early time course of actin purse-string assembly and to characterize other cytoskeletal components of the contractile machinery, we have followed the healing of incisional or slash wounds on the dorsum of the chick wing; these wounds take only seconds to create and heal within similar to 6 h. Healing of the epithelium depends on a combination of purse-string contraction and zipper-like closure of the gap between the cut edges of the epithelium. Confocal laser scanning microscope studies show that actin initially aligns into a cable at the wound margin in the basal layer of the epidermis within similar to 2 min of wounding. Coincident with actin cable assembly, we see localization of cadherins into clusters at the wound margin, presumably marking the sites where segments of the cable in adjacent cells are linked via adherens junctions. A few minutes later we also see localization of myosin II at the wound margin, as expected if myosin is being recruited into the cable to generate a contractile force for wound healing. At the time of wounding, cells at the wound edge become transiently leaky, allowing us to load them with reagents that block the function of two small GTPases, Rho and Rac, which recently have been shown to play key roles in reorganization of the actin cytoskeleton in tissue-culture cells (Hall, A. 1994. Annu. Rev. Cell Biol. 10:31-54). Loading wound edge epidermal cells with C3 transferase, a bacterial exoenzyme that inactivates endogenous Rho, prevents assembly of an actin cable and causes a failure of healing. No such effects are seen with N17rac, a dominant inhibitory mutant Rac protein. These findings support the view that in this system the actin cable is required for healing-both the purse-string contraction and the zipping up-and that Rho is required for formation of the actin cable.