Pasteurella multocida toxin, a potent intracellularly acting mitogen, induces p125FAK and paxillin tyrosine phosphorylation, actin stress fiber formation, and focal contact assembly in Swiss 3T3 cells.
Treatment of Swiss 3T3 cells with recombinant Pasteurella multocida toxin (rPMT), a potent intracellularly acting mitogen, stimulated tyrosine phosphorylation of multiple substrates including bands of M(r) 110,000-130,000 and M(r) 70,000-80,000. Tyrosine phosphorylation induced by rPMT occurred after a pronounced lag period (1 h) and was blocked by either lysosomotrophic agents or incubation at 22 degrees C. Focal adhesion kinase (p125FAK) and paxillin are prominent substrates for rPMT-stimulated tyrosine phosphorylation. Tyrosine phosphorylation by rPMT could be dissociated from both protein kinase C activation and the mobilization of calcium from intracellular stores. rPMT stimulated striking actin stress fiber formation and focal adhesion assembly in Swiss 3T3 cells. Cytochalasin D, which disrupts the actin cytoskeleton, completely inhibited rPMT-induced tyrosine phosphorylation. In addition, tyrosine phosphorylation of p125FAK and paxillin in response to rPMT was completely abolished when cells were subsequently treated with platelet-derived growth factor at a concentration (30 ng/ml) that disrupted the actin cytoskeleton. Our results demonstrate for the first time that rPMT, a bacterial toxin, induces tyrosine phosphorylation of p125FAK and paxillin and promotes actin stress fiber formation and focal adhesion assembly in Swiss 3T3 cells.
Imperial Cancer Research Fund, London, United Kingdom.
H M
HM
Lacerda
A J
AJ
Lax
E
E
Rozengurt
D016475:3T3 Cells; D036002:ADP Ribose Transferases / Q000494:pharmacology; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001905:Botulinum Toxins; D002118:Calcium / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051379:Mice; D008845:Microinjections; D008934:Mitogens / Q000633:toxicity; D016979:Pasteurella multocida / Q000378:metabolism*; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D000199:Actins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D008934:Mitogens; C062258:Pasteurella multocida toxin; D051419:Paxillin; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; C496062:Pxn protein, mouse; D014443:Tyrosine; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse; D011493:Protein Kinase C; D001905:Botulinum Toxins; D002118:Calcium