Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Eur J Cell Biol. 2011 Feb-Mar;90(2-3):143-56. doi: 10.1016/j.ejcb.2010.07.006. Epub 2010 Aug 17.
Cell adhesion to the extracellular matrix is mediated by adhesion receptors, mainly integrins, which upon interaction with the extracellular matrix, bind to the actin cytoskeleton via their cytoplasmic domains. This association is mediated by a variety of scaffold and signaling proteins, which control the mechanical and signaling activities of the adhesion site. Upon transformation of fibroblasts with active forms of Src (e.g., v-Src), focal adhesions are disrupted, and transformed into dot-like contacts known as podosomes, and consisting of a central actin core surrounded by an adhesion ring. To clarify the mechanism underlying Src-dependent modulation of the adhesive phenotype, and its influence on podosome organization, we screened for the effect of siRNA-mediated knockdown of tyrosine kinases, MAP kinases and phosphatases on the reorganization of the adhesion-cytoskeleton complex, induced by a constitutively active Src mutant (SrcY527F). In this screen, we discovered several genes that are involved in Src-induced remodeling of the actin cytoskeleton. We further showed that knockdown of Src in osteoclasts abolishes the formation of the podosome-based rings and impairs cell spreading, without inducing stress fiber development. Our work points to several genes that are involved in this process, and sheds new light on the molecular plasticity of integrin adhesions.
细胞与细胞外基质的黏附是通过黏附受体（主要是整合素）介导的，这些受体与细胞外基质相互作用后，通过其细胞质结构域与肌动蛋白细胞骨架结合。这种结合是通过各种支架和信号蛋白介导的，这些蛋白控制着黏附部位的机械和信号活性。当成纤维细胞被具有活性的Src（例如 v-Src）转化时，焦点黏附会被破坏，并转化为点状接触，称为 Podosomes，由一个中央肌动蛋白核心和一个黏附环组成。为了阐明Src 依赖性调节黏附表型的机制及其对 Podosomes 组织的影响，我们筛选了 siRNA 介导的酪氨酸激酶、MAP 激酶和磷酸酶的敲低对由组成性激活的 Src 突变体（SrcY527F）诱导的黏附-细胞骨架复合物的重组的影响。在该筛选中，我们发现了几个参与 Src 诱导的肌动蛋白细胞骨架重排的基因。我们进一步表明，在破骨细胞中敲低 Src 会破坏基于 Podosomes 的环的形成并损害细胞铺展，而不会诱导应力纤维的发育。我们的工作指出了几个参与这一过程的基因，并为整合素黏附的分子可塑性提供了新的认识。
