The extracellular nucleotide UTP is a potent inducer of hematopoietic stem cell migration.
Homing and engraftment of hematopoietic stem cells (HSCs) to the bone marrow (BM) involve a complex interplay between chemokines, cytokines, and nonpeptide molecules. Extracellular nucleotides and their cognate P2 receptors are emerging as key factors of inflammation and related chemotactic responses. In this study, we investigated the activity of extracellular adenosine triphosphate (ATP) and uridine triphosphate (UTP) on CXCL12-stimulated CD34+ HSC chemotaxis. In vitro, UTP significantly improved HSC migration, inhibited cell membrane CXCR4 down-regulation by migrating CD34+ cells, and increased cell adhesion to fibronectin. In vivo, preincubation with UTP significantly enhanced the BM homing efficiency of human CD34+ cells in immunodeficient mice. Pertussis toxin blocked CXCL12- and UTP-dependent chemotactic responses, suggesting that G-protein alpha-subunits (Galphai) may provide a converging signal for CXCR4- and P2Y-activated transduction pathways. In addition, gene expression profiling of UTP- and CXCL12-treated CD34+ cells and in vitro inhibition assays demonstrated that Rho guanosine 5'-triphosphatase (GTPase) Rac2 and downstream effectors Rho GTPase-activated kinases 1 and 2 (ROCK1/2) are involved in UTP-promoted/CXCL12-dependent HSC migration. Our data suggest that UTP may physiologically modulate the homing of HSCs to the BM, in concert with CXCL12, via the activation of converging signaling pathways between CXCR4 and P2Y receptors, involving Galphai proteins and RhoGTPases.
Rossi
Lara
L
Institute of Hematology and Medical Oncology L & A Seràgnoli, University of Bologna, and Stem Cell Research Center, S. Orsola-Malpighi Hospital, Italy.
Manfredini
Rossella
R
Bertolini
Francesco
F
Ferrari
Davide
D
Fogli
Miriam
M
Zini
Roberta
R
Salati
Simona
S
Salvestrini
Valentina
V
Gulinelli
Sara
S
Adinolfi
Elena
E
Ferrari
Sergio
S
Di Virgilio
Francesco
F
Baccarani
Michele
M
Lemoli
Roberto M
RM
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000328:Adult; D000818:Animals; D018952:Antigens, CD34 / Q000187:drug effects / Q000378:metabolism; D001853:Bone Marrow / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D019718:Receptors, CXCR4 / Q000187:drug effects / Q000378:metabolism; D012016:Reference Values; D014500:Uracil Nucleotides / Q000494:pharmacology*; D014544:Uridine Triphosphate / Q000494:pharmacology*; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D018952:Antigens, CD34; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D044385:GTP-Binding Protein alpha Subunits; D019718:Receptors, CXCR4; D014500:Uracil Nucleotides; D000255:Adenosine Triphosphate; D020741:rho GTP-Binding Proteins; D014544:Uridine Triphosphate