Department of Animal Sciences, Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH 44691, USA.
Cell Biol Int. 2012 May 1;36(5):433-40. doi: 10.1042/CBI20110467.
S4 (syndecan-4) is a cell membrane heparan sulfate proteoglycan that functions in muscle growth and development. It is composed of a central core protein and two types of side chains: GAGs (glycosaminoglycans) and N-glycosylated (N-linked glycosylated) chains. The N-glycosylated chains and GAG chains are required for S4 to regulate turkey myogenic satellite cell proliferation. The objective of the current study was to determine whether the S4 side chains regulate cell proliferation through muscle cell focal adhesion formation and apoptosis. S4 mutants with only one or without any N-glycosylated chains attached to the core protein with or without GAG chains were generated to study the function of N-glycosylated chains and the interaction between N-glycosylated chains and GAG chains. The wild-type S4 and all of the S4 side chain mutants were transfected into turkey myogenic satellite cells. Cell apoptosis and focal adhesion formation were measured, and PKCα (protein kinase Cα) cell membrane localization was investigated. S4 increased FAK (focal adhesion kinase) activity and the deletion of the side chains decreased this effect. S4 and the S4 mutants had no effect on β1-integrin expression, but increased the cell membrane localization of β1-integrin and PKCα. Furthermore, cell apoptosis and vinculin containing focal adhesions were not affected by S4 and its mutants. The results suggest that S4 and its side chains play important roles in regulating FAK activity, and PKCα and β1-integrin cell membrane localization, but not cell apoptosis and vinculin-containing focal adhesion formation.
S4（黏附素-4）是一种细胞表面硫酸乙酰肝素蛋白聚糖，在肌肉生长和发育中起作用。它由一个中心核心蛋白和两种类型的侧链组成：糖胺聚糖（GAGs）和 N-糖基化（N-连接糖基化）链。N-糖基化链和 GAG 链是 S4 调节火鸡骨骼肌卫星细胞增殖所必需的。本研究的目的是确定 S4 侧链是否通过肌细胞焦点粘附形成和细胞凋亡来调节细胞增殖。生成了仅带有一个或不带有任何附着在核心蛋白上的 N-糖基化链的 S4 突变体，以及带有或不带有 GAG 链的 S4 突变体，以研究 N-糖基化链的功能以及 N-糖基化链和 GAG 链之间的相互作用。将野生型 S4 和所有 S4 侧链突变体转染到火鸡骨骼肌卫星细胞中。测量细胞凋亡和焦点粘附形成，并研究 PKCα（蛋白激酶 Cα）细胞膜定位。S4 增加了 FAK（粘着斑激酶）的活性，而侧链的缺失则降低了这种作用。S4 和 S4 突变体对 β1-整合素的表达没有影响，但增加了 β1-整合素和 PKCα的细胞膜定位。此外，S4 及其突变体对细胞凋亡和含有 vinculin 的粘着斑没有影响。结果表明，S4 及其侧链在调节 FAK 活性以及 PKCα和 β1-整合素的细胞膜定位方面发挥着重要作用，但不影响细胞凋亡和含有 vinculin 的粘着斑的形成。
