title: Differential regulation of the α-globin locus by Krüppel-like Factor 3 in erythroid and non-erythroid cells.
abstract: BACKGROUND
  Krüppel-like Factor 3 (KLF3) is a broadly expressed zinc-finger transcriptional repressor with diverse biological roles. During erythropoiesis, KLF3 acts as a feedback repressor of a set of genes that are activated by Krüppel-like Factor 1 (KLF1). Noting that KLF1 binds α-globin gene regulatory sequences during erythroid maturation, we sought to determine whether KLF3 also interacts with the α-globin locus to regulate transcription.
  
  
  RESULTS
  We found that expression of a human transgenic α-globin reporter gene is markedly up-regulated in fetal and adult erythroid cells of Klf3-/- mice. Inspection of the mouse and human α-globin promoters revealed a number of canonical KLF-binding sites, and indeed, KLF3 was shown to bind to these regions both in vitro and in vivo. Despite these observations, we did not detect an increase in endogenous murine α-globin expression in Klf3-/- erythroid tissue. However, examination of murine embryonic fibroblasts lacking KLF3 revealed significant de-repression of α-globin gene expression. This suggests that KLF3 may contribute to the silencing of the α-globin locus in non-erythroid tissue. Moreover, ChIP-Seq analysis of murine fibroblasts demonstrated that across the locus, KLF3 does not occupy the promoter regions of the α-globin genes in these cells, but rather, binds to upstream, DNase hypersensitive regulatory regions.
  
  
  CONCLUSIONS
  These findings reveal that the occupancy profile of KLF3 at the α-globin locus differs in erythroid and non-erythroid cells. In erythroid cells, KLF3 primarily binds to the promoters of the adult α-globin genes, but appears dispensable for normal transcriptional regulation. In non-erythroid cells, KLF3 distinctly binds to the HS-12 and HS-26 elements and plays a non-redundant, albeit modest, role in the silencing of α-globin expression.
authors.forename: Alister P W
authors.initials: AP
authors.lastname: Funnell
authors.forename: Douglas
authors.initials: D
authors.lastname: Vernimmen
authors.forename: Wooi F
authors.initials: WF
authors.lastname: Lim
authors.forename: Ka Sin
authors.initials: KS
authors.lastname: Mak
authors.forename: Beeke
authors.initials: B
authors.lastname: Wienert
authors.forename: Gabriella E
authors.initials: GE
authors.lastname: Martyn
authors.forename: Crisbel M
authors.initials: CM
authors.lastname: Artuz
authors.forename: Jon
authors.initials: J
authors.lastname: Burdach
authors.forename: Kate G R
authors.initials: KG
authors.lastname: Quinlan
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Higgs
authors.forename: Emma
authors.initials: E
authors.lastname: Whitelaw
authors.forename: Richard C M
authors.initials: RC
authors.lastname: Pearson
authors.affiliation: School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia. m.crossley@unsw.edu.au.
authors.forename: Merlin
authors.initials: M
authors.lastname: Crossley
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D041905:Erythroid Cells / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D020014:K562 Cells; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics; D055542:alpha-Globins / Q000235:genetics* / Q000378:metabolism
chemical_list: D051741:Kruppel-Like Transcription Factors; D055542:alpha-Globins; C080774:erythroid Kruppel-like factor