Involvement of the Rho-kinase/myosin light chain kinase pathway on human monocyte chemotaxis induced by ATL-1, an aspirin-triggered lipoxin A4 synthetic analog.
Lipoxins (LX) are arachidonic acid metabolites able to induce monocyte chemotaxis in vitro and in vivo. Nonetheless, the signaling pathways mediating this process are yet unclear. In this study, we have investigated the mechanisms associated with human monocyte activation in response to 15-epi-16-(para-fluoro)-phenoxy-LXA4 (ATL-1), a stable 15-epi-LXA4 analog. Our results demonstrate that ATL-1-induced monocyte chemotaxis (10-300 nM) is inhibited by pertussis toxin, suggesting an effect via the G-protein-linked LXA4 receptor. Monocytes stimulated with the analog presented an increased ERK-2 phosphorylation, which was reduced by PD98059, a selective inhibitor of the MEK 1/2 pathway. After exposure of the cells to ATL-1, myosin L chain kinase (MLCK) phosphorylation was evident and this effect was inhibited by PD98059 or Y-27632, a specific inhibitor of Rho kinase. In addition, Y-27632 abolished ERK-2 activation, suggesting that the MAPK pathway is downstream of Rho/Rho kinase in MLCK activation induced by ATL-1. The specific MLCK inhibitor ML-7, as well as Y-27632, abrogated monocyte chemotaxis stimulated by the analog, confirming the central role of the Rho kinase/MLCK pathway on ATL-1 action. Together, these results indicate that ATL-1 acts as a potent monocyte chemoattractant via Rho kinase and MLCK. The present study clarifies some of the mechanisms involved on the activation of monocytes by LXs and opens new avenues for investigation of these checkpoint controllers of inflammation.
Simões
Rafael L
RL
Departamento de Farmacologia e Psicobiologia, Instituto de Biologia Roberto Alcāntara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brasil.
Fierro
Iolanda M
IM
D000199:Actins / Q000378:metabolism; D001241:Aspirin / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology*; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D044045:Lipoxins / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000276:immunology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology*; D044042:Receptors, Formyl Peptide / Q000502:physiology; D044067:Receptors, Lipoxin / Q000502:physiology; D054460:rho-Associated Kinases
C447621:16-(4-fluorophenoxy)lipoxin A4; D000199:Actins; C105101:FPR2 protein, human; D018836:Inflammation Mediators; D047908:Intracellular Signaling Peptides and Proteins; D044045:Lipoxins; D044042:Receptors, Formyl Peptide; D044067:Receptors, Lipoxin; C040527:lipoxin A4; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D019950:Mitogen-Activated Protein Kinase 1; D001241:Aspirin