Identification of a novel heparin-binding site in the alternatively spliced IIICS region of fibronectin: roles of integrins and proteoglycans in cell adhesion to fibronectin splice variants
Identification of a novel heparin-binding site in the alternatively spliced IIICS region of fibronectin: roles of integrins and proteoglycans in cell adhesion to fibronectin splice variants
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DOI：
10.1016/s0945-053x(00)00131-1
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发表时间：
2001-02-01
期刊：
影响因子：
6.9
通讯作者：
Humphries, MJ
中科院分区：
文献类型：
--
作者：
Mostafavi-Pour, Z;Askari, JA;Humphries, MJ
细胞外基质分子纤连蛋白（FN）是一种糖蛋白，其主要功能特性是支持细胞粘附。FN包含至少两个不同的细胞结合结构域：中央细胞结合结构域和HepII/IIICS区域。HepII区包含III型重复序列12-14，并含有蛋白聚糖结合位点，而可变剪接的IIICS片段具有主要的α 4 β 1整联蛋白结合位点。细胞表面蛋白聚糖和整合素对于介导细胞粘附到FN的该区域是重要的。通过比较肝素结合不同的重组剪接变异体的HepII/IIICS区域，证据是获得了一个新的肝素结合位点的中心IIICS的存在。在该区域的碱性氨基酸序列的定点突变减少肝素结合到重组HepII/IIICS蛋白，并与HepII区域的突变，引起协同活性损失。使用FN的H/120变体（其含有III型重复12-15和全长IIICS区域）和FN的H/95变体（其含有III型重复12-15但缺乏高亲和力整合素结合LDV序列），研究了细胞表面蛋白聚糖和整合素在介导细胞粘附中所起的相对作用。这是通过研究抗整联蛋白抗体和外源性肝素对A375黑色素瘤细胞附着到野生型和H/120和H/95的三种不同突变体的影响来实现的，其中潜在的蛋白聚糖结合位点被部分或完全去除。A375细胞粘附H/120及其突变体被发现涉及整合素和细胞表面蛋白聚糖结合的合作行动，虽然整合素作出了主导贡献。抗整联蛋白抗体和外源性肝素能够抑制黑色素瘤细胞粘附到H/95，在这种情况下，粘附主要是由于细胞表面蛋白聚糖，而不是整联蛋白结合。(C)2001 Elsevier Science B.V./国际矩阵生物学学会。All rights reserved.
The extracellular matrix molecule fibronectin (FN) is a glycoprotein whose major functional property is to support cell adhesion. FN contains at least two distinct cell-binding domains: the central cell-binding domain and the HepII/IIICS region. The HepII region comprises type III repeats 12-14 and contains proteoglycan-binding sites, while the alternatively spliced IIICS segment possesses the major alpha4 beta1 integrin-binding sites. Both cell surface proteoglycans and integrins are important for mediating the adhesion of cells to this region of FN. By comparing heparin binding to different recombinant splice variants of the HepII/IIICS region, evidence was obtained for the existence of a novel heparin-binding site in the centre of the IIICS. Site-directed mutagenesis of basic amino acid sequences in this region reduced heparin binding to recombinant HepII/IIICS proteins and, in conjunction with mutations in the HepII region, caused a synergistic loss of activity. Using the H/120 variant of FN, which contains type III repeats 12-15 and the full-length IIICS region, and the H/95 variant of FN, which contains type III repeats 12-15 but lacks the high affinity integrin-binding LDV sequence, the relative roles played by cell-surface proteoglycans and integrins in mediating cell adhesion have been investigated. This was achieved by studying the effects of anti-integrin antibodies and exogenous heparin on A375 melanoma cell attachment to the wild-type and three different mutants of H/120 and H/95 in which the potential proteoglycan-binding sites were partially or completely removed. A375 cell adhesion to H/120 and its mutants was found to involve the co-operative action of both integrin and cell-surface proteoglycan binding, although integrin made a dominant contribution. Anti-integrin antibodies and exogenous heparin were capable of inhibiting melanoma cell adhesion to H/95 and in this case adhesion was due primarily to cell-surface proteoglycan and not integrin binding. (C) 2001 Elsevier Science B.V./International Society of Matrix Biology. All rights reserved.