Wong W S, Luk J M
Department of Pharmacology, Faculty of Medicine, National University of Singapore, Republic of Singapore.
Biochem Biophys Res Commun. 1997 Jul 18;236(2):479-82. doi: 10.1006/bbrc.1997.6986.
Pertussis toxin (PTX) was thought to bind Mac-1 integrin receptor (CD11b/CD18) on TGF-beta1/D3-primed U937 cells and induced cellular adhesion to serum-coated plate. The present study was to investigate the signal transduction pathway utilized by PTX to initiate myeloid cell adhesion in serum. Immunoblotting study showed that PTX induced tyrosine phosphorylation of two cytoplasmic proteins of 150 kDa and 90 kDa in TGF-beta1/D3-primed U937 cells in a time-dependent manner. In addition, PTX-induced myelomonocytic cell adhesion was abolished in the presence of genistein (100 microM), a specific tyrosine kinase inhibitor. 2LPM19c (2 microg/ml), a mouse monoclonal antibody against the CD11b subunit of Mac-1 integrin, or ethylenediamine tetraacetic acid (EDTA, 5 mM) prevented PTX-mediated U937 cell adhesion. On the other hand, nifedipine (1 microM), a calcium channel blocker, significantly reduced PTX-induced U937 cell adhesion. Taken together, it is suggested that binding of PTX to Mac-1 integrin receptor on primed U937 cells triggers protein tyrosine phosphorylation and, to a lesser extent, Ca(+2) influx, which eventually lead to monocytic cell adhesion in serum.
百日咳毒素（PTX）被认为可与经转化生长因子-β1/D3预处理的U937细胞上的Mac-1整合素受体（CD11b/CD18）结合，并诱导细胞黏附于血清包被的平板。本研究旨在探究PTX在血清中启动髓样细胞黏附所利用的信号转导途径。免疫印迹研究表明，PTX能以时间依赖的方式诱导经转化生长因子-β1/D3预处理的U937细胞中两种分子量分别为150 kDa和90 kDa的细胞质蛋白发生酪氨酸磷酸化。此外，在存在特异性酪氨酸激酶抑制剂染料木黄酮（100 microM）的情况下，PTX诱导的髓单核细胞黏附被消除。抗Mac-1整合素CD11b亚基的小鼠单克隆抗体2LPM19c（2 microg/ml）或乙二胺四乙酸（EDTA，5 mM）可阻止PTX介导的U937细胞黏附。另一方面，钙通道阻滞剂硝苯地平（1 microM）可显著降低PTX诱导的U937细胞黏附。综上所述，提示PTX与预处理的U937细胞上的Mac-1整合素受体结合可触发蛋白酪氨酸磷酸化，并在较小程度上导致Ca(+2)内流，最终导致单核细胞在血清中黏附。
