Involvement of phosphoinositide 3-kinase gamma, Rac, and PAK signaling in chemokine-induced macrophage migration.
In macrophages, chemotactic stimuli cause the activation of Rac and PAK, but little is known about the signaling pathways involved and their role in chemotactic gradient sensing. Herein, we report that in macrophages, the chemokine RANTES (regulated on activation normal T cell expressed and secreted)/CCL5 activates the small GTPase Rac and its downstream target PAK2 within seconds. This response depends on Gi activation and largely on the subsequent triggering of phosphoinositide 3-kinase gamma (PI3Kgamma) and Rac. Retroviral transduction of tagged Rac1 and -2 indicates that RANTES/CCL5-mediated activation of PI3Kgamma triggers Rac1 but not Rac2. In agreement, silencing of Rac1 by shRNA blocks PAK2 activity and inhibits RANTES/CCL5-induced macrophage polarization and directional migration. On the other hand, the tyrosine kinase receptor agonist CSF-1 activates PAK2 independently of PI3Kgamma and Rac. Our results thus demonstrate a chemokine-specific signaling pathway in which Gi and PI3Kgamma coordinate to drive Rac1 and PAK2 activation that eventually controls the chemotactic response.
Serono Pharmaceutical Research Institute, Serono International S.A., 14 Chemin des Aulx, CH 1228 Plan-les-Ouates, Geneva, Switzerland.
Cornelia
C
Weiss-Haljiti
Christian
C
Pasquali
Hong
H
Ji
Corine
C
Gillieron
Christian
C
Chabert
Marie-Laure
ML
Curchod
Emilio
E
Hirsch
Anne J
AJ
Ridley
Rob
R
Hooft van Huijsduijnen
Montserrat
M
Camps
Christian
C
Rommel
D000818:Animals; D002465:Cell Movement; D002469:Cell Separation; D018946:Chemokine CCL5 / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism*; D002633:Chemotaxis; D002867:Chromones / Q000494:pharmacology; D058544:Class Ib Phosphatidylinositol 3-Kinase; D004789:Enzyme Activation; D000939:Epitopes; D005434:Flow Cytometry; D020868:Gene Silencing; D019833:Genistein / Q000494:pharmacology; D015151:Immunoblotting; D007527:Isoenzymes / Q000502:physiology*; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D018715:Microscopy, Video; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D013997:Time Factors; D054462:p21-Activated Kinases
D018946:Chemokine CCL5; D018925:Chemokines; D002867:Chromones; D058544:Class Ib Phosphatidylinositol 3-Kinase; D000939:Epitopes; D019833:Genistein; D007527:Isoenzymes; D016173:Macrophage Colony-Stimulating Factor; D009025:Morpholines; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D012313:RNA; D012333:RNA, Messenger; D054462:p21-Activated Kinases; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C546764:Pik3cg protein, mouse; C515905:Pak1 protein, mouse