title: Direct signal transduction via functional interferon-alphabeta receptors in CD34+ hematopoietic stem cells.
abstract: Affinity purified, freshly isolated CD34+ progenitors were shown to express low levels of type I interferon (IFN) receptors (740 +/- 60 binding sites/cell, K(d) 0.7 +/- 0.04 nM) determined by Scatchard's analysis using a radiolabelled, neutralizing, monoclonal antibody directed against the IFNAR1 chain of the human type I IFN receptor. Treatment of freshly isolated (day 0), highly purified (>95% pure) CD34+ cells with recombinant IFN-alpha resulted in rapid tyrosine phosphorylation and activation of STAT1, Tyk2 and JAK1 as shown by Western immunoblotting. Similarly, IFN treatment was shown by confocal microscopy to result in rapid nuclear localization of the transcription factors IRF1 and STAT2, demonstrating the presence of functional IFN receptors on freshly isolated (day 0) CD34+ cells. The number of specific type I IFN receptor binding sites expressed on hematopoietic progenitor cells increased to some 1440 +/- 40 per cell after 11 days of cultivation of CD34+ cells in vitrosuggesting that receptor expression increases with cell differentiation. IFN-mediated signal transduction and the inhibitory effect of IFN-alpha on 7 or 14 days CFU-GM and BFU-E colony formation was abrogated in the presence of the anti-IFNAR1 mAb, indicating that IFN-alpha acts directly on the proliferation of human hematopoietic progenitor cells via receptor activated signal transduction without excluding the induction of other cytokines or growth factors by residual accessory cells.
authors.affiliation: Laboratoire d'Oncologie Virale, UPR 9045, CNRS, Villejuif, France.
authors.forename: J
authors.initials: J
authors.lastname: Giron-Michel
authors.forename: D
authors.initials: D
authors.lastname: Weill
authors.forename: G
authors.initials: G
authors.lastname: Bailly
authors.forename: S
authors.initials: S
authors.lastname: Legras
authors.forename: P C
authors.initials: PC
authors.lastname: Nardeux
authors.forename: B
authors.initials: B
authors.lastname: Azzarone
authors.forename: M G
authors.initials: MG
authors.lastname: Tovey
authors.forename: P
authors.initials: P
authors.lastname: Eid
mesh_terms: D021581:Active Transport, Cell Nucleus; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018952:Antigens, CD34 / Q000032:analysis*; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D050856:Interferon Regulatory Factor-1; D016898:Interferon-alpha / Q000037:antagonists & inhibitors; D053613:Janus Kinase 1; D007700:Kinetics; D008565:Membrane Proteins; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000037:antagonists & inhibitors / Q000276:immunology / Q000502:physiology*; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015398:Signal Transduction; D053634:TYK2 Kinase; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D018952:Antigens, CD34; D004268:DNA-Binding Proteins; C507964:IFNAR1 protein, human; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; D016898:Interferon-alpha; D008565:Membrane Proteins; D010750:Phosphoproteins; D011506:Proteins; D017471:Receptors, Interferon; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D015534:Trans-Activators; D053633:Receptor, Interferon alpha-beta; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human