Integrin alpha2beta1 is a receptor for the cartilage matrix protein chondroadherin.
Integrin alpha2beta1 is a receptor for the cartilage matrix protein chondroadherin.
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DOI：
10.1083/jcb.138.5.1159
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发表时间：
1997-09-08
期刊：
影响因子：
--
通讯作者：
Lundgren-Akerlund E
中科院分区：
文献类型：
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作者：
Camper L;Heinegârd D;Lundgren-Akerlund E
软骨粘附素（36 kD蛋白质）是一种富含亮氨酸的软骨基质蛋白，已知可介导分离软骨细胞的粘附。在本研究中，我们研究了细胞表面蛋白参与的相互作用的细胞与软骨粘附素在细胞粘附和亲和纯化。牛关节软骨细胞与软骨粘附素包被的培养皿的粘附依赖于Mg 2+或Mn 2+，而不依赖于Ca 2+。粘附被识别β 1整合素亚基的抗体部分抑制。软骨细胞裂解物中的软骨粘附素结合蛋白在软骨粘附素-琼脂糖凝胶上进行亲和纯化。β 1整联蛋白抗体从EDTA洗脱材料中免疫沉淀分子量为110和140 kD（非还原）的两种蛋白质。这些结果表明软骨细胞上的β 1整联蛋白与软骨粘附素相互作用。为了鉴定参与细胞与蛋白质相互作用的α整合素亚基，我们从人成纤维细胞中亲和纯化软骨粘附素结合膜蛋白。亲和柱EDTA洗脱物的免疫沉淀鉴定α 2 β 1为软骨粘附素结合整联蛋白。这些结果与细胞粘附实验一致，其中针对整联蛋白亚基α 2的抗体部分抑制人成纤维细胞和人软骨细胞与软骨粘附素的粘附。由于α 2 β 1也是II型胶原蛋白的受体，我们测试了针对α 2亚基的不同抗体抑制T47 D细胞与II型胶原蛋白和软骨粘附素粘附的能力。结果表明，与II型胶原和软骨粘附素的粘附涉及α 2 β 1整合素上的相似或邻近位点。虽然α 2 β 1是II型胶原和软骨粘附素的受体，但发现仅细胞与II型胶原的粘附介导了扩散。
Chondroadherin (the 36-kD protein) is a leucine-rich, cartilage matrix protein known to mediate adhesion of isolated chondrocytes. In the present study we investigated cell surface proteins involved in the interaction of cells with chondroadherin in cell adhesion and by affinity purification. Adhesion of bovine articular chondrocytes to chondroadherin-coated dishes was dependent on Mg2+ or Mn2+ but not Ca2+. Adhesion was partially inhibited by an antibody recognizing β1 integrin subunit. Chondroadherin-binding proteins from chondrocyte lysates were affinity purified on chondroadherin-Sepharose. The β1 integrin antibody immunoprecipitated two proteins with molecular mass ∼110 and 140 kD (nonreduced) from the EDTA-eluted material. These results indicate that a β1 integrin on chondrocytes interacts with chondroadherin. To identify the α integrin subunit(s) involved in interaction of cells with the protein, we affinity purified chondroadherin-binding membrane proteins from human fibroblasts. Immunoprecipitation of the EDTA-eluted material from the affinity column identified α2β1 as a chondroadherin-binding integrin. These results are in agreement with cell adhesion experiments where antibodies against the integrin subunit α2 partially inhibited adhesion of human fibroblast and human chondrocytes to chondroadherin. Since α2β1 also is a receptor for collagen type II, we tested the ability of different antibodies against the α2 subunit to inhibit adhesion of T47D cells to collagen type II and chondroadherin. The results suggested that adhesion to collagen type II and chondroadherin involves similar or nearby sites on the α2β1 integrin. Although α2β1 is a receptor for both collagen type II and chondroadherin, only adhesion of cells to collagen type II was found to mediate spreading.