Institute of Complex Systems 7, Biomechanics, Forschungszentrum Jülich, 52425 Jülich, Germany.
Eur J Cell Biol. 2012 Feb;91(2):118-28. doi: 10.1016/j.ejcb.2011.10.003. Epub 2011 Dec 16.
Recognition of external mechanical signals by cells is an essential process for life. One important mechanical signal experienced by various cell types, e.g. around blood vessels, within the lung epithelia or around the intestine, is cyclic stretch. As a response, many cell types reorient their actin cytoskeleton and main cell axis almost perpendicular to the direction of stretch. Despite the vital necessity of cellular adaptation to cyclic stretch, the underlying mechanosensory signal cascades are far from being understood. Here we show an important function of Src-family kinase activity in cellular reorientation upon cyclic stretch. Deletion of all three family members, namely c-Src, Yes and Fyn (SYF), results in a strongly impaired cell reorientation of mouse embryonic fibroblasts with an only incomplete reorientation upon expression of c-Src. We further demonstrate that this reorientation phenotype of SYF-depleted cells is not caused by affected protein exchange dynamics within focal adhesions or altered cell force generation. Instead, Src-family kinases regulate the reorientation in a mechanotransduction-dependent manner, since knock-down and knock-out of p130Cas, a putative stretch sensor known to be phosphorylated by Src-family kinases, also reduce cellular reorientation upon cyclic stretch. This impaired reorientation is identical in intensity upon mutating stretch-sensitive tyrosines of p130Cas only. These statistically highly significant data pinpoint early events in a Src family kinase- and p130Cas-dependent mechanosensory/mechanotransduction pathway.
细胞对外界机械信号的识别是生命的一个基本过程。各种细胞类型都经历过一种重要的机械信号，例如血管周围、肺上皮细胞内或肠道周围的循环拉伸。作为一种反应，许多细胞类型会重新定向它们的肌动蛋白细胞骨架和主细胞轴，使其几乎垂直于拉伸的方向。尽管细胞适应循环拉伸的必要性至关重要，但机械敏感信号级联仍远未被理解。在这里，我们展示了 Src 家族激酶活性在细胞对循环拉伸的重新定向中的重要功能。删除所有三个家族成员，即 c-Src、Yes 和 Fyn (SYF)，导致小鼠胚胎成纤维细胞的细胞重新定向严重受损，只有在表达 c-Src 时才会出现不完全重新定向。我们进一步证明，SYF 耗尽细胞的这种重新定向表型不是由于粘着斑内的蛋白质交换动力学受到影响或细胞力产生改变所致。相反，Src 家族激酶以依赖机械转导的方式调节重新定向，因为 p130Cas 的敲低和敲除，p130Cas 是一种已知被 Src 家族激酶磷酸化的假定拉伸传感器，也会减少细胞在循环拉伸时的重新定向。仅突变 p130Cas 的拉伸敏感酪氨酸，这种受损的重新定向在强度上是相同的。这些具有统计学高度显著性的数据确定了 Src 家族激酶和 p130Cas 依赖的机械敏感/机械转导途径中的早期事件。
