title: Ku86 autoantigen related protein-1 transcription initiates from a CpG island and is induced by p53 through a nearby p53 response element.
abstract: The human Ku86 gene and an isoform, KARP-1 (Ku86 autoantigen related protein-1), encode overlapping, but differentially regulated, transcripts. Ku86 is constitutively transcribed at high levels and, although it plays a seminal role in DNA double-strand break repair, its expression is not induced by DNA damage. KARP-1, in contrast, is expressed constitutively only at low levels and its expression is induced by DNA damage in a p53-dependent fashion. The regulatory elements promoting KARP-1 gene expression and p53 responsiveness, however, were unknown. Here, we report that a strong DNase I hypersensitive site (DHS) resides approximately 25 kb upstream from the Ku86 promoter. This DHS is encompassed by a hypomethylated CpG island. Reporter assays demonstrated that this region corresponded to a promoter(s), which promoted transcription of peroxisomal trans-2-enoyl CoA reductase in the centromeric direction and KARP-1 in the telomeric direction. KARP-1 primer extension products were mapped to this CpG island in the correct transcriptional orientation confirming that KARP-1 transcription initiates from this site. Moreover, a p53 response element within the first intron of the KARP-1 transcriptional unit was identified using chromatin immunoprecipitation and antibodies specific to activated forms of p53. These data expand our understanding of this important DNA repair locus.
authors.affiliation: Department of Molecular Biology, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
authors.forename: Corey D
authors.initials: CD
authors.lastname: Braastad
authors.forename: Mariana
authors.initials: M
authors.lastname: Leguia
authors.forename: Eric A
authors.initials: EA
authors.lastname: Hendrickson
mesh_terms: D024506:5' Flanking Region; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D018899:CpG Islands; D004265:DNA Helicases; D019175:DNA Methylation; D003850:Deoxyribonuclease I / Q000737:chemistry; D044943:Fatty Acid Desaturases / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D000072200:Ku Autoantigen; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; D012333:RNA, Messenger / Q000096:biosynthesis; D011839:Radiation, Ionizing; D020218:Response Elements; D024363:Transcription Initiation Site; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D044943:Fatty Acid Desaturases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C434934:trans-2-enoyl-CoA reductase (NADPH); D009247:NADH, NADPH Oxidoreductases; D003850:Deoxyribonuclease I; D004265:DNA Helicases; C106893:XRCC5 protein, human; D000072200:Ku Autoantigen