Role of phosphatidylinositol 3-kinase in the binding of Bordetella pertussis to human monocytes.
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.
Ishibashi
Yoshio
Y
Department of Immunobiology, Meiji Pharmaceutical University, Noshio, Kiyose, Tokyo 204-8588, Japan.
Yoshimura
Katsuaki
K
Nishikawa
Akemi
A
Claus
Sarah
S
Laudanna
Carlo
C
Relman
David A
DA
D015703:Antigens, CD / Q000378:metabolism; D001422:Bacterial Adhesion; D001886:Bordetella pertussis / Q000378:metabolism / Q000472:pathogenicity*; D051928:CD47 Antigen; D002352:Carrier Proteins / Q000378:metabolism; D006388:Hemagglutinins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism / Q000382:microbiology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
D015703:Antigens, CD; D051928:CD47 Antigen; D002352:Carrier Proteins; D006388:Hemagglutinins; D039302:Integrin alphaVbeta3; D016177:Macrophage-1 Antigen; D019869:Phosphatidylinositol 3-Kinases; D011506:Proteins; D014443:Tyrosine; C497894:CD47 protein, human