Integrin expression by primary and immortalized human chondrocytes:: evidence of a differential role for α1β1 and α2β1 integrins in mediating chondrocyte adhesion to types II and VI collagen
Integrin expression by primary and immortalized human chondrocytes:: evidence of a differential role for α1β1 and α2β1 integrins in mediating chondrocyte adhesion to types II and VI collagen
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DOI：
10.1053/joca.1999.0277
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发表时间：
2000-03-01
影响因子：
7
通讯作者：
Goldring, MB
中科院分区：
文献类型：
--
作者：
Loeser, RF;Sadiev, S;Goldring, MB
目的：软骨细胞在体外和原位均可表达含有pi的整合素，但其在软骨细胞功能调节中的作用尚不清楚。本研究的目的是确定不同整合素的相对表达如何与软骨细胞的分化状态和增殖能力有关。设计：研究四种不同细胞系在猿猴病毒40大T抗原(SV40-Tag)永生化的人软骨细胞系中整合素的表达，并与原代软骨细胞进行比较。结果：四种永生化细胞系细胞表面的pi整合素表达水平均高于原代细胞，且整合素α2和α3亚基的表达水平是原代细胞的10倍以上。然而，原代细胞表达较高水平的α1整合素亚单位，而T/C28a4细胞不表达，而在其他细胞系中表达水平不同或较低。在高增殖的青少年肋软骨细胞系(T/C-28a4、C-2812和C-20a4)中，A3整合素亚单位的表达水平显著高于原代关节软骨细胞和来自成人关节软骨细胞的TST/AC-62细胞。除了在C-20/A4细胞中的表达水平平均高出4倍外，在原代细胞和细胞系中的表达水平相似。细胞黏附实验显示，α1β1和α2β1均可作为软骨细胞对II型和VI型胶原的黏附受体。在表达这两种整合素的细胞系中，α1β1是VI型胶原的优先受体，而α2β1是II型胶原的优先受体。与A3封闭抗体P1B5共同孵育的C-28/12细胞与纤维连接蛋白和II型胶原的粘附率分别增加67%和100%，而不是抑制粘附率。结论：SV40-Tag永生化可以改变软骨细胞整合素的表达。α1、α2和α3亚基相对水平的变化可能显著改变软骨细胞与细胞外基质中的II型和VI型胶原相互作用的方式。(C)2000年国际骨性关节炎研究会。
Objective: Chondrocytes have been shown to express pi-containing integrins both in vitro and in situ, but their role in regulating chondrocyte function is poorly understood. The objective of this study was to determine how the relative expression of different integrins may be modulated in relation to the differentiated state and proliferative capacity of the chondrocyte.Design: Integrin expression by four different cell lines of human chondrocytes immortalized with Simian virus 40 large T-antigen (SV40-TAg) was studied and compared to primary chondrocytes. Differences in alpha 1 and alpha 2 integrin subunit expression were utilized to further study the role of these integrins in mediating adhesion to types II and VI collagen.Results: The overall cell-surface levels of pi-containing integrins were higher on all four immortalized cell lines which expressed over 10-fold higher levels of alpha 2 and alpha 3 integrin subunits compared to primary cells. However, primary cells expressed higher levels of the alpha 1 integrin subunit which was not expressed by T/C28a4 cells and expressed at variable and lower levels in the other lines. Levels of the a3 integrin subunit were significantly greater on the highly proliferative juvenile costal chondrocyte lines (T/C-28a4, C-2812, and C-20a4) compared to primary articular chondrocytes and tsT/AC-62 cells which were derived from adult articular chondrocytes. Expression of alpha 5 was similar among primary cells and cell lines except on C-20/A4 cells which had an average of over 4-fold higher levels. None of the primary or immortalized chondrocytes tested expressed significant levels of alpha 4. Cell adhesion assays revealed that both alpha 1 beta 1 and alpha 2 beta 1 could serve as chondrocyte adhesion receptors for types II and VI collagen. In cell lines expressing both integrins, alpha 1 beta 1 was the preferential receptor for type VI collagen while alpha 2 beta 1 was the preferential receptor for type II collagen. Rather than inhibiting adhesion, Incubation with the a3 blocking antibody P1B5 increased adhesion of C-28/12 cells to both fibronectin and type II collagen by 67% and 100% respectively.Conclusions: Immortalization with SV40-TAg results in altered integrin expression by chondrocytes. Changes in the relative levels of alpha 1, alpha 2, and alpha 3 subunits may significantly alter the manner in which chondrocytes interact with types II and VI collagen in the extracellular matrix. (C) 2000 OsteoArthritis Research Society International.