title: Phosphatidylinositol 3-kinase/Akt induced by erythropoietin renders the erythroid differentiation factor GATA-1 competent for TIMP-1 gene transactivation.
abstract: The contribution of erythropoietin to the differentiation of the red blood cell lineage remains elusive, and the demonstration of a molecular link between erythropoietin and the transcription of genes associated with erythroid differentiation is lacking. In erythroid cells, expression of the tissue inhibitor of matrix metalloproteinase (TIMP-1) is strictly dependent on erythropoietin. We report here that erythropoietin regulates the transcription of the TIMP-1 gene upon binding to its receptor in erythroid cells by triggering the activation of phosphatidylinositol 3-kinase (PI3K)/Akt. We found that Akt directly phosphorylates the transcription factor GATA-1 at serine 310 and that this site-specific phosphorylation is required for the transcriptional activation of the TIMP-1 promoter. This chain of events can be recapitulated in nonerythroid cells by transfection of the implicated molecular partners, resulting in the expression of the normally silent endogenous TIMP-1 gene. Conversely, TIMP-1 secretion is profoundly decreased in erythroid cells from fetal livers of transgenic knock-in mice homozygous for a GATA(S310A) gene, which encodes a GATA-1 mutant that cannot be phosphorylated at Ser(310). Furthermore, retrovirus-mediated expression of GATA(S310A) into GATA-1(null)-derived embryonic stem cells decreases the rate of hemoglobinization by more than 50% compared to expressed wild-type GATA-1. These findings provide the first example of a chain of coupling mechanisms between the binding of erythropoietin to its receptor and GATA-1-dependent gene expression.
authors.affiliation: Department of d'Hématologie, Institute Cochin, INSERM U56, CNRS UMR 8104, Université René Descartes Hospital Cochin, Paris, France.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Kadri
authors.forename: Leila
authors.initials: L
authors.lastname: Maouche-Chretien
authors.forename: Heather M
authors.initials: HM
authors.lastname: Rooke
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Orkin
authors.forename: Paul-Henri
authors.initials: PH
authors.lastname: Romeo
authors.forename: Patrick
authors.initials: P
authors.lastname: Mayeux
authors.forename: Philippe
authors.initials: P
authors.lastname: Leboulch
authors.forename: Stany
authors.initials: S
authors.lastname: Chretien
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism*; D050981:Erythroid-Specific DNA-Binding Factors; D004921:Erythropoietin / Q000494:pharmacology*; D050982:GATA1 Transcription Factor; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D017467:Receptors, Erythropoietin / Q000378:metabolism; D015398:Signal Transduction; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D004921:Erythropoietin; D050982:GATA1 Transcription Factor; D019869:Phosphatidylinositol 3-Kinases; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D017467:Receptors, Erythropoietin; D019715:Tissue Inhibitor of Metalloproteinase-1; D014157:Transcription Factors; C494688:GATA1 protein, human; C494689:Gata1 protein, mouse; C494918:AKT1 protein, human