Adamsky K, Schilling J, Garwood J, Faissner A, Peles E
Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.
Oncogene. 2001 Feb 1;20(5):609-18. doi: 10.1038/sj.onc.1204119.
The extracellular domain of receptor protein tyrosine phosphatase beta (RPTPbeta) is composed of several domains which mediate its interactions with distinct ligands present on the surface of either neurons or glial cells. Here, we demonstrate that the fibronectin type III domain (FNIII) of RPTPbeta binds to glial tumor-derived cell lines and primary astrocytes. We used affinity purification to isolate several proteins that specifically bind to the FNIII domain of RPTPbeta. One of these, a 240 kDa protein that was purified from U118MG glioblastoma cell, was identified as tenascin C based on the amino acid sequence of several tryptic peptides. The interaction of RPTPbeta with tenascin C was found to mediate cell adhesion. Adhesion and spreading of SF763T astrocytoma cells expressing RPTPbeta on tenascin C was specifically abolished by the addition of a soluble fragment containing the FNIII domain of the receptor. RPTPbeta-dependent cell adhesion was mediated by binding to the alternatively spliced FNIII repeats A1,2,4 (TnfnA1,2,4) of tenascin C. Furthermore, COS cells expressing RPTPbeta adhere to TnfnA1,2,4, while the parental cells did not. These results demonstrate that the FNIII domain of RPTPbeta binds to tenascin C and suggest that RPTPbeta present on glial tumor cells is a primary adhesion receptor system to the extracellular matrix.
受体蛋白酪氨酸磷酸酶β（RPTPβ）的细胞外结构域由多个结构域组成，这些结构域介导其与神经元或神经胶质细胞表面存在的不同配体的相互作用。在此，我们证明RPTPβ的纤连蛋白III型结构域（FNIII）与胶质肿瘤衍生的细胞系和原代星形胶质细胞结合。我们使用亲和纯化法分离出几种与RPTPβ的FNIII结构域特异性结合的蛋白质。其中一种从U118MG胶质母细胞瘤细胞中纯化出的240 kDa蛋白质，根据几个胰蛋白酶肽段的氨基酸序列被鉴定为腱生蛋白C。发现RPTPβ与腱生蛋白C的相互作用介导细胞黏附。通过添加含有受体FNIII结构域的可溶性片段，特异性地消除了表达RPTPβ的SF763T星形细胞瘤细胞在腱生蛋白C上的黏附和铺展。RPTPβ依赖性细胞黏附是通过与腱生蛋白C的可变剪接FNIII重复序列A1、2、4（TnfnA1、2、4）结合介导的。此外，表达RPTPβ的COS细胞黏附于TnfnA1、2、4，而亲本细胞则不黏附。这些结果表明RPTPβ的FNIII结构域与腱生蛋白C结合，并提示胶质肿瘤细胞上存在的RPTPβ是细胞外基质的主要黏附受体系统。
