title: The GATA1s isoform is normally down-regulated during terminal haematopoietic differentiation and over-expression leads to failure to repress MYB, CCND2 and SKI during erythroid differentiation of K562 cells.
abstract: BACKGROUND
  Although GATA1 is one of the most extensively studied haematopoietic transcription factors little is currently known about the physiological functions of its naturally occurring isoforms GATA1s and GATA1FL in humans-particularly whether the isoforms have distinct roles in different lineages and whether they have non-redundant roles in haematopoietic differentiation. As well as being of general interest to understanding of haematopoiesis, GATA1 isoform biology is important for children with Down syndrome associated acute megakaryoblastic leukaemia (DS-AMKL) where GATA1FL mutations are an essential driver for disease pathogenesis.
  
  
  METHODS
  Human primary cells and cell lines were analyzed using GATA1 isoform specific PCR. K562 cells expressing GATA1s or GATA1FL transgenes were used to model the effects of the two isoforms on in vitro haematopoietic differentiation.
  
  
  RESULTS
  We found no evidence for lineage specific use of GATA1 isoforms; however GATA1s transcripts, but not GATA1FL transcripts, are down-regulated during in vitro induction of terminal megakaryocytic and erythroid differentiation in the cell line K562. In addition, transgenic K562-GATA1s and K562-GATA1FL cells have distinct gene expression profiles both in steady state and during terminal erythroid differentiation, with GATA1s expression characterised by lack of repression of MYB, CCND2 and SKI.
  
  
  CONCLUSIONS
  These findings support the theory that the GATA1s isoform plays a role in the maintenance of proliferative multipotent megakaryocyte-erythroid precursor cells and must be down-regulated prior to terminal differentiation. In addition our data suggest that SKI may be a potential therapeutic target for the treatment of children with DS-AMKL.
authors.affiliation: Institute of Infection, Immunity and Inflammation, Level 3, Glasgow Biomedical Research Centre, 120, University Place, Glasgow, G12 8TA, UK. chris.halsey@glasgow.ac.uk
authors.forename: Christina
authors.initials: C
authors.lastname: Halsey
authors.forename: Marie
authors.initials: M
authors.lastname: Docherty
authors.forename: Mhairi
authors.initials: M
authors.lastname: McNeill
authors.forename: Derek
authors.initials: D
authors.lastname: Gilchrist
authors.forename: Michelle
authors.initials: M
authors.lastname: Le Brocq
authors.forename: Brenda
authors.initials: B
authors.lastname: Gibson
authors.forename: Gerard
authors.initials: G
authors.lastname: Graham
mesh_terms: D002454:Cell Differentiation / Q000502:physiology; D045744:Cell Line, Tumor; D055513:Connective Tissue Growth Factor / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics; D015536:Down-Regulation; D041905:Erythroid Cells / Q000166:cytology*; D050982:GATA1 Transcription Factor / Q000235:genetics*; D006410:Hematopoiesis / Q000235:genetics*; D006801:Humans; D020014:K562 Cells; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb / Q000235:genetics*
chemical_list: C526317:CCN2 protein, human; D004268:DNA-Binding Proteins; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; C060614:SKI protein, human; D055513:Connective Tissue Growth Factor