title: Flt3 ligand and the Flt3 receptor regulate hematopoietic cell migration by modulating the SDF-1alpha(CXCL12)/CXCR4 axis.
abstract: Flt3 ligand (FL) enhances hematopoietic cell proliferation and facilitates hematopoietic stem cell mobilization in vivo, while the stromal-derived factor 1alpha (SDF-1alpha, CXC ligand 12 [CXCL12])/CXC receptor 4 (CXCR4) axis is critical for their homing and trafficking. We investigated if FL and its receptor, Flt3, functionally interact with CXCL12/CXCR4 to regulate hematopoietic cell migration. FL stimulated chemokinetic activity when used alone, but synergistically enhanced short-term migration of CD34+ cells, Ba/F3 cells expressing human Flt3 (Ba/F3-Flt3), and human RS4;11 acute leukemia cells, induced by CXCL12. Moreover, overexpression of constitutively activated internal tandem duplication (ITD)-Flt3 mutants in Ba/F3 cells dramatically enhanced migration toward CXCL12. In Ba/F3-Flt3 cells, synergistic cell migration to FL plus CXCL12 was associated with enhanced phosphorylation of mitogen-activated protein kinase p42/p44 (MAPK(p42/p44)), cyclic adenosine monophosphate response element binding protein (CREB), and Akt, and was partially inhibited by pretreatment of cells with selective inhibitors for MAPK(p42/p44), protein kinase A (PKA), or phosphatidylinositol 3-kinase (PI3-kinase), implicating these pathways in migration to FL plus CXCL12. In contrast, prolonged exposure of CD34+ or Ba/F3-Flt3 cells to FL down-regulated CXCR4 expression, inhibited CXCL12-mediated phosphorylation of MAPK(p42/p44), CREB, and Akt, and impaired migration toward CXCL12. These findings suggest that FL/Flt3 may facilitate hematopoietic cell migration/homing and mobilization by enhancing or inhibiting CXCL12/CXCR4 signaling pathways and that the FL/Flt3 axis participates in trafficking of normal and transformed hematopoietic cells.
authors.affiliation: Department of Microbiology & Immunology and the Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA. sfukuda@iupui.edu
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Hal E
authors.initials: HE
authors.lastname: Broxmeyer
authors.forename: Louis M
authors.initials: LM
authors.lastname: Pelus
mesh_terms: D000208:Acute Disease; D018952:Antigens, CD34 / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D002461:Cell Line, Transformed; D002465:Cell Movement / Q000502:physiology*; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology; D016195:G2 Phase / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007938:Leukemia; D020935:MAP Kinase Signaling System / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D019718:Receptors, CXCR4 / Q000378:metabolism*; D016196:S Phase / Q000502:physiology; D014407:Tumor Cells, Cultured; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D018952:Antigens, CD34; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019718:Receptors, CXCR4; C084881:flt3 ligand protein; D019869:Phosphatidylinositol 3-Kinases; C497970:FLT3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; D017868:Cyclic AMP-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3