Andrä K, Nikolic B, Stöcher M, Drenckhahn D, Wiche G
Institute of Biochemistry and Molecular Cell Biology, Vienna Biocenter, 1030 Vienna, Austria.
Genes Dev. 1998 Nov 1;12(21):3442-51. doi: 10.1101/gad.12.21.3442.
Plectin, a major linker and scaffolding protein of the cytoskeleton, has been shown to be essential for the mechanical integrity of skin, skeletal muscle, and heart. Studying fibroblast and astroglial cell cultures derived from plectin (-/-) mice, we found that their actin cytoskeleton, including focal adhesion contacts, was developed more extensively than in wild-type cells. Also it failed to show characteristic short-term rearrangments in response to extracellular stimuli activating the Rho/Rac/Cdc42 signaling cascades. As a consequence, cell motility, adherence, and shear stress resistance were altered, and morphogenic processes were delayed. Furthermore, we show that plectin interacts with G-actin in vitro in a phosphatidylinositol-4,5-biphosphate-dependent manner and associates with actin stress fibers in living cells. The actin stress fiber phenotype of plectin-deficient fibroblasts could be reversed to a large degree by transient transfection of full-length plectin or plectin fragments containing the amino-terminal actin-binding domain (ABD). These results reveal a novel role of plectin as regulator of cellular processes involving actin filament dynamics that goes beyond its proposed role in scaffolding and mechanical stabilization of cells.
网蛋白是细胞骨架的一种主要连接和支架蛋白，已被证明对皮肤、骨骼肌和心脏的机械完整性至关重要。通过研究源自网蛋白基因敲除（-/-）小鼠的成纤维细胞和星形胶质细胞培养物，我们发现它们的肌动蛋白细胞骨架，包括粘着斑连接，比野生型细胞发育得更广泛。此外，它未能显示出对激活Rho/Rac/Cdc42信号级联的细胞外刺激作出的特征性短期重排。结果，细胞运动性、粘附性和抗剪切应力发生改变，形态发生过程延迟。此外，我们表明网蛋白在体外以磷脂酰肌醇-4,5-二磷酸依赖性方式与G-肌动蛋白相互作用，并在活细胞中与肌动蛋白应力纤维相关联。通过瞬时转染全长网蛋白或含有氨基末端肌动蛋白结合结构域（ABD）的网蛋白片段，可以在很大程度上逆转网蛋白缺陷型成纤维细胞的肌动蛋白应力纤维表型。这些结果揭示了网蛋白作为涉及肌动蛋白丝动力学的细胞过程调节剂的新作用，这超出了其在细胞支架和机械稳定方面所提出的作用。
