title: Involvement of mitogen-activated protein kinase in the cytokine-regulated phosphorylation of transcription factor GATA-1.
abstract: Gene-targeting experiments in transgenic mice have revealed an essential role for GATA-1 in the normal differentiation and development of erythroid cells. GATA-1 is phosphorylated in vivo on seven of its serine residues; the regulation and function of GATA-1 phosphorylation, however, is not understood. Here we demonstrate a role for MAP kinase (MAPK) signalling in the control of GATA-1 phosphorylation. We show that EGF-induced MAPK signalling results in the phosphorylation of ectopically expressed GATA-1 in COS cells. This phosphorylation can be positively or negatively regulated by genetic manipulation of the MAPK pathway through expression of constitutively activated, or dominant-negative, mutants of MAPK kinase (MAPKK), an upstream regulator of MAPK activity. In vitro phosphorylation experiments using purified MAPK and either recombinant GATA-1 or synthetic GATA-1 peptides suggest that GATA-1 is a MAPK substrate with MAPK phosphorylation occurring primarily on Ser26 and Ser178. We also show that GATA-1 is phosphorylated in factor-dependent haemopoietic progenitor cells in response to cytokine-induced signalling. Through the further use of a dominant-negative MAPKK mutant as well as chemical inhibitors of specific MAPKs, we identify ERK as an in vivo GATA-1 kinase. Finally, we demonstrate that mutation of serines 26 and 178 compromises the ability of GATA-1 to interact with the LIM-only protein LMO2 when both proteins are expressed in COS cells. These data implicate receptor-mediated signalling through the MAPK pathway as a control point in the regulation of transcription factor GATA-1.
authors.affiliation: The Institute of Cancer Research, 237 Fulham Road, London B, UK.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Towatari
authors.forename: Marco
authors.initials: M
authors.lastname: Ciro
authors.forename: Sergio
authors.initials: S
authors.lastname: Ottolenghi
authors.forename: Shinobu
authors.initials: S
authors.lastname: Tsuzuki
authors.forename: Tariq
authors.initials: T
authors.lastname: Enver
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D006133:Growth Substances / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D015183:Restriction Mapping; D012694:Serine; D014157:Transcription Factors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494689:Gata1 protein, mouse; D006133:Growth Substances; D007377:Interleukin-3; D010748:Phosphopeptides; D011994:Recombinant Proteins; D014157:Transcription Factors; D012694:Serine; D020928:Mitogen-Activated Protein Kinases