N-Formyl peptide receptor ligation induces rac-dependent actin reorganization through Gbeta gamma subunits and class Ia phosphoinositide 3-kinases.
The N-formyl peptide receptor is a G protein-coupled transmembrane receptor involved in stimulating a variety of differential responses in neutrophils including chemotaxis, degranulation, superoxide production, transcriptional activation, and actin reorganization. Although it is known that N-formyl-Met-Leu-Phe induces actin reorganization, the sequence of events from the receptor to the actin cytoskeleton is not well characterized. To study the signaling pathway from the N-formyl peptide receptor to the actin cytoskeleton, we developed a model system utilizing microinjection techniques with a nonhematopoietic cell line. An expression vector coding for the N-formyl peptide receptor was microinjected into porcine aortic endothelial cells and stimulated with N-formyl-Met-Leu-Phe to induce actin reorganization and membrane ruffling. The receptor-mediated signal was blocked by pertussis toxin and by a dominant negative Rac-N17, indicating the involvement of G(i)alpha subunit and the small guanosine triphosphatase Rac, respectively. Moreover, Gbetagamma subunits and membrane targeted forms of phosphatidylinositol (PI) 3-kinase alpha were sufficient to induce similar actin reorganization, and coexpression of various mutants of PI 3-kinase with the N-formyl peptide receptor identified a link to class Ia PI-3 kinase-mediated actin reorganization.
Belisle
B
B
Onyx Pharmaceuticals, Richmond, California 94806, USA.
Abo
A
A
D000199:Actins / Q000378:metabolism*; D000818:Animals; D018076:DNA, Complementary / Q000008:administration & dosage; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins; D008845:Microinjections; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism*; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010957:Plasmids; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism*; D013552:Swine; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D020744:rac GTP-Binding Proteins / Q000378:metabolism*
D000199:Actins; D018076:DNA, Complementary; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; D010566:Virulence Factors, Bordetella; D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins; D020744:rac GTP-Binding Proteins