Lampugnani M G, Bernasconi S, Neri P, Lozzi L, Gavazzi I, Marchisio P C, Dejana E
Instituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
Lab Invest. 1991 Jul;65(1):96-103.
Some integrin receptors have been reported to be functionally distinct in different cell types. In endothelial and melanoma cells, the vitronectin receptor, alpha v beta 3 binds fibrinogen (fg) and von Willebrand factor (vWf) in addition to vitronectin itself, whereas it fails to do so in MG-63 osteosarcoma cells. In this report, it is shown that, in the presence of Mn2+, MG-63 cells attach more efficiently to vitronectin and acquire the de novo capacity to adhere to fg- and vWf-coated surfaces. The latter phenomenon occurs with full cell spreading, F-actin microfilament organization, and alpha v and beta 3 clustering at focal contacts. In contrast, beta 1 and beta 5 do not localize to adhesion plaques under the same experimental conditions. An antiserum to the beta 3 chain and a synthetic peptide containing the sequence Gly-Arg-Gly-Asp-Ser-Pro block MG-63 attachment to fg and vWf in the presence of Mn2+. The minimal active concentration of Mn2+ is in the range of 0.1 to 1 microns. These data suggest that the acquired capacity of MG-63 to attach to fg and vWf in the presence of Mn2+ is mediated by alpha v beta 3 and that differences in alpha v beta 3 receptor specificity may be modulated by exogenous factors.
据报道，一些整合素受体在不同细胞类型中功能各异。在内皮细胞和黑色素瘤细胞中，玻连蛋白受体αvβ3除了能结合玻连蛋白本身外，还能结合纤维蛋白原（fg）和血管性血友病因子（vWf），而在MG-63骨肉瘤细胞中则不能。在本报告中，研究表明，在存在Mn2+的情况下，MG-63细胞能更有效地附着于玻连蛋白，并获得了黏附于fg和vWf包被表面的新能力。后一种现象伴随着细胞的完全铺展、F-肌动蛋白微丝组织以及αv和β3在黏着斑处的聚集。相比之下，在相同实验条件下，β1和β5并不定位于黏附斑。针对β3链的抗血清以及包含序列甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸-脯氨酸的合成肽，在存在Mn2+的情况下可阻断MG-63细胞对fg和vWf的附着。Mn2+的最小活性浓度在0.1至1微米范围内。这些数据表明，MG-63细胞在存在Mn2+时获得的黏附于fg和vWf的能力是由αvβ3介导的，并且αvβ3受体特异性的差异可能受到外源性因素的调节。
