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CD34+ and Treatment with UTP and CXCL12

ABSTRACT: Homing and engraftment of hematopoietic stem cells (HSCs) to the bone marrow (BM) involve a complex interplay between chemokines, cytokines, and non-peptide 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 of migrating CD34+ cells and increased cell adhesion to fibronectin. In vivo, pre-incubation 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 (Gαi) may provide a converging signal for CXCR4- and P2Y-activated transduction pathways. In addition, gene expression profiling of UTP-treated CD34+ cells and in vitro inhibition assays demonstrated that Rho guanosine 5’-triphosphatases (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 migration of HSCs and their homing to the BM, in concert with CXCL12, via the activation of converging signaling pathways between CXCR4 and P2Y receptors, involving Gαi proteins and RhoGTPases. Keywords: treatment comparison

ORGANISM(S): Homo sapiens

PROVIDER: GSE5168 | GEO | 2006/10/04

SECONDARY ACCESSION(S): PRJNA96575

REPOSITORIES: GEO

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Project description:Nucleotides triphosphates are extracellular messengers binding to specific plasma membrane receptors (P2Rs) that modulate responses as different as proliferation, differentiation, migration or cell death on several cell types including hematopoietic stem cells. Little and controversial information is available on the role of extracellular nucleotides in human mesenchimal stem cells (hMSCs). In this study, we assessed whether P2Rs are expressed and functional in bone marrow-derived hMSCs. Our results demonstrated, at the mRNA and protein level, the expression of all P2X and P2Y receptor subtypes identified so far. P2R activation by their natural ligands adenosine triphosphate (ATP) and uridine triphosphate (UTP) induced in hMSCs, intracellular Ca2+ concentration changes, plasma membrane depolarization and permeabilization. hMSCs were resistant to the cytotoxic effects of high dose ATP despite the expression of permeabilizing P2Rs as demonstrated by the lack of morphological changes, significant release of intracellular markers of cell death or modification of the mitochondrial network. Gene expression profiling revealed the down-regulation of cell proliferation genes whereas genes involved in cell migration and cytokine production were strongly up-regulated by ATP. Functional studies confirmed the inhibitory activity of ATP on proliferation of hMSCs and clonogenic progenitors. Moreover, ATP exerted a chemotactic effect on hMSCs and increased their migration in response to the chemokine CXCL12. Finally, whereas ATP did not affect T-cell inhibitory activity of hMSCs, the nucleotide increased the production of pro-inflammatory cytokines by hMSCs. Thus, our data show that purinergic signaling modulates hMSC functions and point to a role for extracellular nucleotides on hMSCs biology. hMSCs from 6 healthy donors were seeded at a density of 2.5 x 103 cells/cm2 for 24 hours with or without 1mM ATP. We then assessed the transcriptome profile of ATPM-bM-^@M-^Streated and untreated cells using Affymetrix HG-U133 Plus 2 GeneChip array.

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CD34+ and Treatment with UTP and CXCL12

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