title: ETO-2 associates with SCL in erythroid cells and megakaryocytes and provides repressor functions in erythropoiesis.
abstract: Lineage specification and cellular maturation require coordinated regulation of gene expression programs. In large part, this is dependent on the activator and repressor functions of protein complexes associated with tissue-specific transcriptional regulators. In this study, we have used a proteomic approach to characterize multiprotein complexes containing the key hematopoietic regulator SCL in erythroid and megakaryocytic cell lines. One of the novel SCL-interacting proteins identified in both cell types is the transcriptional corepressor ETO-2. Interaction between endogenous proteins was confirmed in primary cells. We then showed that SCL complexes are shared but also significantly differ in the two cell types. Importantly, SCL/ETO-2 interacts with another corepressor, Gfi-1b, in red cells but not megakaryocytes. The SCL/ETO-2/Gfi-1b association is lost during erythroid differentiation of primary fetal liver cells. Genetic studies of erythroid cells show that ETO-2 exerts a repressor effect on SCL target genes. We suggest that, through its association with SCL, ETO-2 represses gene expression in the early stages of erythroid differentiation and that alleviation/modulation of the repressive state is then required for expression of genes necessary for terminal erythroid maturation to proceed.
authors.affiliation: MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom.
authors.forename: Anna H
authors.initials: AH
authors.lastname: Schuh
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Tipping
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Clark
authors.forename: Isla
authors.initials: I
authors.lastname: Hamlett
authors.forename: Boris
authors.initials: B
authors.lastname: Guyot
authors.forename: Francesco J
authors.initials: FJ
authors.lastname: Iborra
authors.forename: Patrick
authors.initials: P
authors.lastname: Rodriguez
authors.forename: John
authors.initials: J
authors.lastname: Strouboulis
authors.forename: Tariq
authors.initials: T
authors.lastname: Enver
authors.forename: Paresh
authors.initials: P
authors.lastname: Vyas
authors.forename: Catherine
authors.initials: C
authors.lastname: Porcher
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism*; D004920:Erythropoiesis; D005786:Gene Expression Regulation; D008533:Megakaryocytes / Q000378:metabolism*; D051379:Mice; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; C117411:Cbfa2t3 protein, mouse; C486395:Gfi1b protein, mouse; C489366:Tal1 protein, mouse