Ku80 gene expression is Sp1-dependent and sensitive to CpG methylation within a novel cis element.
The Ku70/80 complex, known as Ku, constitutes the DNA end binding component of the DNA-dependent protein kinase (DNA-PK). We have characterized the promoter region of the mouse and human Ku80 genes to delineate transcriptional elements necessary for basal gene expression and proliferation-dependent regulation. Consensus Sp1 recognition elements were identified in both promoters, and were determined to be essential for basal expression. We further identified a near-perfect palindrome of 21 base pairs located immediately 5' to one Sp1 element. This sequence was present once within the mouse Ku80 promoter and seven times, in a head-to-tail tandem array, within the human Ku80 promoter. This sequence possessed homology with a methylation-sensitive promoter element, Enh2, present in the LTR of mouse intractisternal A-particles. Promoter deletion studies and expression analysis of in-vitro methylated reporter gene constructs provided strong evidence that, in vivo, this repeat sequence regulates Ku80 gene expression in cis, through a mechanism involving CpG methylation. Evidence is also presented, suggesting that Ku is directly involved in this regulatory process.
Ludwig
D L
DL
Life Sciences Division, Los Alamos National Laboratory, NM 87545, USA.
Chen
F
F
Peterson
S R
SR
Nussenzweig
A
A
Li
G C
GC
Chen
D J
DJ
D000818:Animals; D034961:Antigens, Nuclear; D001483:Base Sequence; D002457:Cell Extracts; D002460:Cell Line; D002467:Cell Nucleus; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015226:Dinucleoside Phosphates / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D000072200:Ku Autoantigen; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D012689:Sequence Homology, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism*
D034961:Antigens, Nuclear; D002457:Cell Extracts; D004247:DNA; D004265:DNA Helicases; D004268:DNA-Binding Proteins; D015226:Dinucleoside Phosphates; D000072200:Ku Autoantigen; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D016329:Sp1 Transcription Factor; C015772:CpG dinucleotide; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse