Gismondi A, Milella M, Palmieri G, Piccoli M, Frati L, Santoni A
Department of Experimental Medicine, University of Rome La Sapienza, Italy.
J Immunol. 1995 Apr 1;154(7):3128-37.
Recent evidence indicates that integrins do transduce signals that are involved in the regulation of a number of cellular processes. We have shown previously that human NK cells express alpha 4 beta 1 and alpha 5 beta 1 integrins, which mediate their adhesion to fibronectin (FN). Here we investigate whether cross-linking of beta 1 FN receptors on human NK cells stimulates tyrosine kinase activation. Our results indicate that cross-linking of beta 1 integrins on NK cells, either freshly isolated from PBL or generated from 10-day coculture of nonadherent PBMC with an irradiated EVB+ lymphoblastoid B cell line (long-term activated NK cells), altered the tyrosine phosphorylation pattern. In particular, we found stimulation of tyrosine phosphorylation of two proteins migrating with an apparent mass of 105 and 115 kDa, which was not observed after CD16 engagement. Phosphorylation of pp105-115 was already observed at 1 min, raised maximal values at 3 to 5 min, and persisted until 20 min after stimulation. Tyrosine phosphorylation of pp105-115 was also observed upon engagement of alpha 4 beta 1 and alpha 5 beta 1 FN receptors either with mAb directed against the alpha subunits or after NK cell adhesion to FN or its 120- and 40-kDa fragments. Pretreatment of NK cells with the tyrosine kinase inhibitor herbimycin A resulted in marked decrease of phosphorylation stimulated through alpha 4 beta 1 and alpha 5 beta 1 integrins, indicating that ligation of FN receptors on NK cells activates tyrosine kinase(s). Overall our results suggest that beta 1 integrins on NK cells play a major role as signaling molecules in the regulation of NK cell functions.
最近的证据表明，整合素确实能转导参与多种细胞过程调节的信号。我们之前已经表明，人类自然杀伤细胞（NK细胞）表达α4β1和α5β1整合素，它们介导NK细胞与纤连蛋白（FN）的黏附。在此，我们研究人类NK细胞上β1 FN受体的交联是否会刺激酪氨酸激酶激活。我们的结果表明，NK细胞上β1整合素的交联，无论是从外周血淋巴细胞（PBL）中新鲜分离的，还是通过非黏附性外周血单核细胞（PBMC）与经照射的EVB + 淋巴母细胞样B细胞系共培养10天产生的（长期活化的NK细胞），都会改变酪氨酸磷酸化模式。特别是，我们发现刺激了两种表观分子量为105和115 kDa的蛋白质的酪氨酸磷酸化，而在CD16参与后未观察到这种情况。在刺激1分钟时就已观察到pp105 - 115的磷酸化，在3至5分钟时达到最大值，并持续到刺激后20分钟。当用针对α亚基的单克隆抗体使α4β1和α5β1 FN受体参与，或NK细胞黏附于FN或其120 kDa和40 kDa片段后，也观察到了pp105 - 115的酪氨酸磷酸化。用酪氨酸激酶抑制剂赫伯霉素A预处理NK细胞，导致通过α4β1和α5β1整合素刺激的磷酸化显著降低，这表明NK细胞上FN受体的连接激活了酪氨酸激酶。总体而言，我们的结果表明，NK细胞上的β1整合素作为信号分子在NK细胞功能调节中起主要作用。
