title: Cloning and characterization of EphA3 (Hek) gene promoter: DNA methylation regulates expression in hematopoietic tumor cells.
abstract: The Eph family of receptor tyrosine kinases (RTK) has restricted temporal and spatial expression patterns during development, and several members are also found to be upregulated in tumors. Very little is known of the promoter elements or regulatory factors required for expression of Eph RTK genes. In this report we describe the identification and characterization of the EphA3 gene promoter region. A region of 86 bp located at -348 bp to -262 bp upstream from the transcription start site was identified as the basal promoter. This region was shown to be active in both EphA3-expressing and -nonexpressing cell lines, contrasting with the widely different levels of EphA3 expression. We noted a region rich in CpG dinucleotides downstream of the basal promoter. Using Southern blot analyses with methylation-sensitive restriction enzymes and bisulfite sequencing of genomic DNA, sites of DNA methylation were identified in hematopoietic cell lines which correlated with their levels of EphA3 gene expression. We showed that EphA3 was not methylated in normal tissues but that a subset of clinical samples from leukemia patients showed extensive methylation, similar to that observed in cell lines. These results suggest that DNA methylation may be an important mechanism regulating EphA3 transcription in hematopoietic tumors.
authors.affiliation: Queensland Institute of Medical Research, Department of Medicine, Herston, Queensland, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Dottori
authors.forename: M
authors.initials: M
authors.lastname: Down
authors.forename: A
authors.initials: A
authors.lastname: Hüttmann
authors.forename: D R
authors.initials: DR
authors.lastname: Fitzpatrick
authors.forename: A W
authors.initials: AW
authors.lastname: Boyd
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D019175:DNA Methylation; D015226:Dinucleoside Phosphates / Q000378:metabolism; D005091:Exons; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007938:Leukemia / Q000235:genetics*; D008969:Molecular Sequence Data; D010179:Pancreas / Q000378:metabolism; D010920:Placenta / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D036121:Receptor, EphA3; D014407:Tumor Cells, Cultured
chemical_list: D020121:5' Untranslated Regions; D015226:Dinucleoside Phosphates; D020794:Receptor Protein-Tyrosine Kinases; D036121:Receptor, EphA3; C015772:CpG dinucleotide; C491718:EPHA3 protein, human