Orend Gertraud, Huang Wentao, Olayioye Monilola A, Hynes Nancy E, Chiquet-Ehrismann Ruth
Friedrich Miescher Institute for Biomedical Research, Novartis Forschungsstiftung, PO Box 2543, CH-4002 Basel, Switzerland.
Oncogene. 2003 Jun 19;22(25):3917-26. doi: 10.1038/sj.onc.1206618.
Tenascin-C is an adhesion-modulatory extracellular matrix protein that is predominantly expressed during embryonic development, wound healing and in tumor stroma. Here we report that anchorage-dependent human, rat and mouse fibroblasts adhere poorly and fail to proliferate on pure tenascin-C. This was due to a significant reduction of cyclin-dependent kinase 2 (cdk2) activity, resulting from elevated expression and association of the cdk inhibitors (CKIs) p21Cip1 and p27Kip1. To analyse the effect of tenascin-C on fibronectin-mediated adhesion, cells were plated on a mixed fibronectin/tenascin-C substratum. Compared to fibronectin alone, cell spreading and adhesion signaling were compromised, as determined by delayed phosphorylation kinetics of focal adhesion kinase (FAK). Despite the presence of growth factors, these cells remained arrested in the G1 phase of the cell cycle. In contrast to cells plated on pure tenascin-C, cdk2 activity appeared to be inhibited independently of CKIs. Interestingly, overexpression of the transmembrane proteoglycan syndecan-4 restored cell spreading, adhesion signaling and DNA replication on the fibronectin/tenascin-C substratum. A similar rescue was observed using a recombinant peptide that spans the syndecan-4-binding site in fibronectin. This indicates that tenascin-C causes cell cycle arrest and cdk2 inactivation by interfering with fibronectin-syndecan-4 interactions. We therefore propose that syndecan-4 signaling plays a central role in the control of cellular proliferation of anchorage-dependent fibroblasts.
腱生蛋白-C是一种调节黏附的细胞外基质蛋白，主要在胚胎发育、伤口愈合及肿瘤基质中表达。在此我们报告，贴壁依赖的人、大鼠和小鼠成纤维细胞在纯腱生蛋白-C上黏附不佳且无法增殖。这是由于细胞周期蛋白依赖性激酶2（cdk2）活性显著降低，这是由细胞周期蛋白依赖性激酶抑制剂（CKIs）p21Cip1和p27Kip1的表达升高及结合所致。为分析腱生蛋白-C对纤连蛋白介导的黏附的影响，将细胞接种在纤连蛋白/腱生蛋白-C混合基质上。与单独的纤连蛋白相比，细胞铺展和黏附信号受到损害，这通过粘着斑激酶（FAK）延迟的磷酸化动力学得以确定。尽管存在生长因子，这些细胞仍停滞在细胞周期的G1期。与接种在纯腱生蛋白-C上的细胞不同，cdk2活性似乎独立于CKIs受到抑制。有趣的是，跨膜蛋白聚糖syndecan-4的过表达恢复了在纤连蛋白/腱生蛋白-C基质上的细胞铺展、黏附信号及DNA复制。使用跨越纤连蛋白中syndecan-4结合位点的重组肽也观察到了类似的拯救作用。这表明腱生蛋白-C通过干扰纤连蛋白-syndecan-4相互作用导致细胞周期停滞和cdk2失活。因此我们提出，syndecan-4信号在贴壁依赖的成纤维细胞的细胞增殖控制中起核心作用。
