Zoppi Nicoletta, Gardella Rita, De Paepe Anne, Barlati Sergio, Colombi Marina
Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, Medical Faculty, University of Brescia, 25123 Brescia, Italy.
J Biol Chem. 2004 Apr 30;279(18):18157-68. doi: 10.1074/jbc.M312609200. Epub 2004 Feb 17.
Dermal fibroblasts derived from types I and IV Ehlers-Danlos syndrome (EDS) patients, carrying mutations in COL5A1 and COL3A1 genes, respectively, synthesize aberrant types V and III collagen (COLL) and show defective organization of these proteins into the extracellular matrix (ECM) and high reduction of their functional receptor, the alpha(2)beta(1) integrin, compared with control fibroblasts. EDS cells also show reduced levels of fibronectin (FN) in the culture medium and lack an FN fibrillar network. Finally, EDS cells prevalently organize alpha(v)beta(3) integrin instead of alpha(5)beta(1) integrin. The alpha(v)beta(3) integrin, distributed on the whole EDS cell surface, shows FN binding and assembly properties when the cells are treated with purified FN. Treatment of EDS cells with purified COLLV or COLLIII, but not with FN, restores the control phenotype (COLL(+), FN(+), alpha(v)beta(3)(-), alpha(5)beta(1)(+), alpha(2)beta(1)(+)). Function-blocking antibodies to COLLV, COLLIII, or alpha(2)beta(1) integrin induce in control fibroblasts an EDS-like phenotype (COLL(-), FN(-), alpha(v)beta(3)(+), alpha(5)beta(1)(-), alpha(2)beta(1)(-)). These results show that in human fibroblasts alpha(2)beta(1) integrin organization and function are controlled by its ligand, and that the alpha(2)beta(1)-COLL interaction, in turn, regulates FN integrin receptor recruitment: high alpha(2)beta(1) integrin levels induce alpha(5)beta(1) integrin organization, while low alpha(2)beta(1) integrin levels lead to alpha(v)beta(3) integrin organization.
分别携带COL5A1和COL3A1基因突变的I型和IV型埃勒斯-当洛综合征（EDS）患者的真皮成纤维细胞，合成异常的V型和III型胶原蛋白（COLL），与对照成纤维细胞相比，这些蛋白质在细胞外基质（ECM）中的组织存在缺陷，且其功能性受体α(2)β(1)整合素的水平大幅降低。EDS细胞在培养基中的纤连蛋白（FN）水平也降低，且缺乏FN纤维网络。最后，EDS细胞主要组装α(v)β(3)整合素而非α(5)β(1)整合素。分布于整个EDS细胞表面的α(v)β(3)整合素，在用纯化的FN处理细胞时表现出FN结合和组装特性。用纯化的COLLV或COLLIII而非FN处理EDS细胞，可恢复对照表型（COLL(+)、FN(+)、α(v)β(3)(-)、α(5)β(1)(+)、α(2)β(1)(+)）。针对COLLV、COLLIII或α(2)β(1)整合素的功能阻断抗体在对照成纤维细胞中诱导出类似EDS的表型（COLL(-)、FN(-)、α(v)β(3)(+)、α(5)β(1)(-)、α(2)β(1)(-)）。这些结果表明，在人成纤维细胞中，α(2)β(1)整合素的组织和功能受其配体控制，并且α(2)β(1)-COLL相互作用进而调节FN整合素受体的募集：高α(2)β(1)整合素水平诱导α(5)β(1)整合素组织形成，而低α(2)β(1)整合素水平导致α(v)β(3)整合素组织形成。
