Echtermeyer F, Baciu P C, Saoncella S, Ge Y, Goetinck P F
Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Building 149, Charlestown, Massachusetts 02129, USA.
J Cell Sci. 1999 Oct;112 ( Pt 20):3433-41. doi: 10.1242/jcs.112.20.3433.
The formation of focal adhesions and actin stress fibers on fibronectin is dependent on signaling through (&bgr;)1 integrins and the heparan sulfate proteoglycan syndecan-4, and we have analyzed the requirement of the glycosaminoglycan chains of syndecan-4 during these events. Chinese hamster ovary cells with mutations in key enzymes of the glycanation process do not synthesize glycosaminoglycan chains and are unable to assemble actin stress fibers and focal contacts when cultured on fibronectin. Transfection of the mutant cells with a cDNA that encodes the core protein of chicken syndecan-4 leads to the production of unglycanated core protein. The overexpression of syndecan-4 core protein in these mutant cells increases cell spreading and is sufficient for these cells to assemble actin stress fibers and focal adhesions similar to wild-type cells seeded on fibronectin and vitronectin matrices. Syndecan-4 core protein colocalizes to focal contacts in mutant cells that have been transfected with the syndecan-4 core protein cDNA. These data indicate an essential role for the core protein of syndecan-4 in the generation of signals leading to actin stress fiber and focal contact assembly.
粘着斑和肌动蛋白应力纤维在纤连蛋白上的形成依赖于通过（β）1整合素和硫酸乙酰肝素蛋白聚糖syndecan-4的信号传导，并且我们已经分析了syndecan-4的糖胺聚糖链在这些事件中的需求。糖基化过程关键酶发生突变的中国仓鼠卵巢细胞不能合成糖胺聚糖链，并且在纤连蛋白上培养时无法组装肌动蛋白应力纤维和粘着斑。用编码鸡syndecan-4核心蛋白的cDNA转染突变细胞会导致未糖基化核心蛋白的产生。这些突变细胞中syndecan-4核心蛋白的过表达增加了细胞铺展，并且足以使这些细胞组装肌动蛋白应力纤维和粘着斑，类似于接种在纤连蛋白和玻连蛋白基质上的野生型细胞。syndecan-4核心蛋白与用syndecan-4核心蛋白cDNA转染的突变细胞中的粘着斑共定位。这些数据表明syndecan-4核心蛋白在导致肌动蛋白应力纤维和粘着斑组装的信号产生中起重要作用。
