Ishibashi Yoshio, Yoshimura Katsuaki, Nishikawa Akemi, Claus Sarah, Laudanna Carlo, Relman David A
Department of Immunobiology, Meiji Pharmaceutical University, Noshio, Kiyose, Tokyo 204-8588, Japan.
Cell Microbiol. 2002 Dec;4(12):825-33. doi: 10.1046/j.1462-5822.2002.00235.x.
Bordetella pertussis, the causative agent of whooping cough, adheres to human monocytes by means of filamentous haemagglutinin (FHA), a bacterial surface protein that is recognized by complement receptor type 3 (CR3, alphaMbeta2 integrin). Previous work has shown that an FHA Arg-Gly-Asp (RGD, residues 1097-1099) site interacts with a complex composed of leucocyte response integrin (LRI, alphavbeta3 integrin) and integrin-associated protein (IAP, CD47) on human monocytes, resulting in enhancement of CR3-mediated bacterial binding. However, the pathway that mediates alphavbeta3-alphaMbeta2 integrin signalling remains to be characterized. Here we describe the involvement of phosphatidylinositol 3-kinase (PI3-K) in this pathway. Wortmannin and LY294002, inhibitors of PI3-K, reduced alphavbeta3/IAP-upregulated, CR3-associated bacterial binding to human monocytes. B. pertussis infection of human monocytes resulted in a marked recruitment of cellular PI3-K to the sites of B. pertussis contact. In contrast, cells infected with an isogenic strain carrying a G1098A mutation at the FHA RGD site did not show any recruitment of PI3-K. We found that ligation of FHA by alphavbeta3/IAP induced RGD-dependent tyrosine phosphorylation of a 60 kDa protein, which associated with IAP and PI3-K in human monocytes. These results suggest that PI3-K and a tyrosine phosphorylated 60 kDa protein may be involved in this biologically important integrin signalling pathway.
百日咳博德特氏菌是百日咳的病原体，它通过丝状血凝素（FHA）黏附于人类单核细胞，FHA是一种细菌表面蛋白，可被3型补体受体（CR3，αMβ2整合素）识别。先前的研究表明，FHA的精氨酸-甘氨酸-天冬氨酸（RGD，第1097 - 1099位氨基酸残基）位点与人类单核细胞上由白细胞反应整合素（LRI，αvβ3整合素）和整合素相关蛋白（IAP，CD47）组成的复合物相互作用，从而增强CR3介导的细菌黏附。然而，介导αvβ3 - αMβ2整合素信号传导的途径仍有待阐明。在此，我们描述了磷脂酰肌醇3激酶（PI3 - K）在该途径中的作用。PI3 - K抑制剂渥曼青霉素和LY294002可减少αvβ3/IAP上调的、与CR3相关的细菌对人类单核细胞的黏附。百日咳博德特氏菌感染人类单核细胞导致细胞PI3 - K显著募集至百日咳博德特氏菌接触位点。相比之下，用在FHA RGD位点携带G1098A突变的同基因菌株感染的细胞未显示出PI3 - K的任何募集。我们发现，αvβ3/IAP对FHA的连接诱导了一种60 kDa蛋白的RGD依赖性酪氨酸磷酸化，该蛋白在人类单核细胞中与IAP和PI3 - K相关。这些结果表明，PI3 - K和一种酪氨酸磷酸化的60 kDa蛋白可能参与了这一具有生物学重要性的整合素信号传导途径。
