Shi Jinghua, Badri Kameswara Rao, Choudhury Ranginee, Schuger Lucia
Department of Pathology, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
Exp Cell Res. 2006 Oct 15;312(17):3432-42. doi: 10.1016/j.yexcr.2006.07.016. Epub 2006 Jul 28.
We previously showed that P311, an intracellular protein involved in cell migration, is found in human wound myofibroblast precursors (proto-myofibroblasts) and myofibroblasts. Furthermore, by binding to the TGF-beta1 latency associated protein (LAP), P311 induced NIH 3T3 cells to transform into non-fibrogenic myofibroblasts characterized by lack of TGF-beta1 production. Here we demonstrate that P311-induced myofibroblasts migrate in an ameboid rather than a mesenchymal pattern. Ameboid migration is characterized by lack of focal adhesions and stress fibers, absence of integrins and MMPs clustering/activation and changes in small GTPases activity, all leading to increased cell motility. P311-induced ameboid migration depended on activation of the GTPase RalA and was reverted to mesenchymal-type migration by RalA RNA interference. Ameboid migration was conserved in cells plated on fibrin, the initial wound matrix, but was switched back to mesenchymal-type migration by collagen I, the main ECM component in late stages of wound healing. TGF-beta1, the major stimulus of collagen production during wound repair, also reversed the ameboid phenotype to mesenchymal. Our studies therefore suggest that, by inducing RalA activity, P311 promotes a motile proto-myofibroblast and myofibroblast phenotype specifically adapted to rapidly populate the initial wound matrix.
我们之前发现，参与细胞迁移的细胞内蛋白P311存在于人类伤口肌成纤维细胞前体（原肌成纤维细胞）和肌成纤维细胞中。此外，P311通过与转化生长因子β1（TGF-β1）潜伏相关蛋白（LAP）结合，诱导NIH 3T3细胞转化为非纤维化的肌成纤维细胞，其特征是不产生TGF-β1。在此，我们证明P311诱导的肌成纤维细胞以阿米巴样而非间充质样模式迁移。阿米巴样迁移的特征是缺乏粘着斑和应力纤维，不存在整合素和基质金属蛋白酶（MMPs）的聚集/激活以及小GTP酶活性的变化，所有这些都会导致细胞运动性增加。P311诱导的阿米巴样迁移依赖于GTP酶RalA的激活，并且通过RalA RNA干扰可恢复为间充质样迁移。在纤维蛋白（初始伤口基质）上培养的细胞中，阿米巴样迁移得以保留，但在伤口愈合后期的主要细胞外基质（ECM）成分I型胶原作用下，又会转变回间充质样迁移。伤口修复过程中胶原蛋白产生的主要刺激因子TGF-β1也会将阿米巴样表型转变为间充质样。因此，我们的研究表明，通过诱导RalA活性，P311促进了一种运动性的原肌成纤维细胞和肌成纤维细胞表型，这种表型特别适合于快速填充初始伤口基质。
