title: Functional analysis of a novel KLF1 gene promoter variation associated with hereditary persistence of fetal hemoglobin.
abstract: Hereditary persistence of fetal hemoglobin (HPFH) is a rare hereditary condition resulting in elevated levels of fetal hemoglobin (HbF) in adults. Typical HPFH is associated with promoter mutations or large deletions affecting the human fetal globin (HBG1 and HBG2) genes, while genetic defects in other genes involved in human erythropoiesis, e.g. KLF1, also result in atypical HPFH. Here, we report the first KLF1 gene promoter mutation (KLF1:g.-148G > A) that is associated with increased HbF level. This mutation was shown to result in drastically reduced CAT reporter gene expression in K562 cells, compared to the wild-type sequence (p = 0.009) and also in reduced KLF1 gene expression in vivo. Furthermore, consistent with in silico analysis, electrophoretic mobility shift analysis showed that the KLF1:g.-148G > A mutation resides in a Sp1 binding site and further that this mutation leads to the ablation of Sp1 binding in vitro. These data suggest that the KLF1:g-148G > A mutation could play a role in increasing HbF levels in adults and further underlines the role of KLF1 as one of the key transcription factors involved in human fetal globin gene switching.
authors.affiliation: Institute of Molecular Genetics and Genetic Engineering, Laboratory for Molecular Hematology, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia.
authors.forename: Milena
authors.initials: M
authors.lastname: Radmilovic
authors.forename: Branka
authors.initials: B
authors.lastname: Zukic
authors.forename: Maja Stojiljkovic
authors.initials: MS
authors.lastname: Petrovic
authors.forename: Marina
authors.initials: M
authors.lastname: Bartsakoulia
authors.forename: Biljana
authors.initials: B
authors.lastname: Stankovic
authors.forename: Nikola
authors.initials: N
authors.lastname: Kotur
authors.forename: Lidija
authors.initials: L
authors.lastname: Dokmanovic
authors.forename: Marianthi
authors.initials: M
authors.lastname: Georgitsi
authors.forename: George P
authors.initials: GP
authors.lastname: Patrinos
authors.forename: Sonja
authors.initials: S
authors.lastname: Pavlovic
mesh_terms: D000328:Adult; D001665:Binding Sites / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005319:Fetal Hemoglobin / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006453:Hemoglobinopathies / Q000235:genetics*; D006801:Humans; D020014:K562 Cells / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000502:physiology; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D060888:Real-Time Polymerase Chain Reaction; D055771:Serbia; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D051741:Kruppel-Like Transcription Factors; D016329:Sp1 Transcription Factor; C080774:erythroid Kruppel-like factor; D005319:Fetal Hemoglobin