Inhibition of Ku autoantigen binding activity to the E2F motif after ultraviolet B irradiation of melanocytic cells

Melanoma Res. 1998 Dec;8(6):471-81. doi: 10.1097/00008390-199812000-00001.

Abstract

In human melanocytes and a human melanoma cell line (MM96L), the level of Ku sequence-specific binding to a 37-mer oligonucleotide containing a single E2F-1 binding site of the c-myc promoter (E2cM) significantly decreased 12 24h after cytostatic exposure to 300 J/m2 ultraviolet B radiation (UVB). No UVB-induced loss was found in fibroblasts, while HeLa cells showed an earlier (4 h) but less significant decrease than melanocytic cells. Equitoxic doses of gamma radiation, cisplatin or UVC had little effect on E2cM-specific binding. The loss of Ku binding in MM96L cells was not the result of translocation of Ku or a decrease in Ku protein or DNA-dependent protein kinase activity. The level of E2cM-specific binding in MM96L cells was increased by tunicamycin (2 microg/ml), an inhibitor of N-linked glycosylation, and decreased by the glucosidase inhibitor castanospermine (50 microg/ml). These results, which parallel the reported loss in melanocytes of the cell cycle regulator pRB after UVB, suggest that the DNA binding activity of Ku is affected by post-translational modification and may play a role in regulating the cell cycle response to UVB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / metabolism
  • Antigens, Nuclear*
  • Blotting, Western
  • Carrier Proteins*
  • Cell Cycle / radiation effects
  • Cell Cycle Proteins*
  • DNA Helicases*
  • DNA-Binding Proteins / metabolism*
  • DNA-Binding Proteins / radiation effects*
  • E2F Transcription Factors
  • E2F1 Transcription Factor
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Inhibitors / pharmacology
  • HeLa Cells
  • Humans
  • Indolizines / metabolism
  • Ku Autoantigen
  • Melanocytes / radiation effects*
  • Melanoma / metabolism
  • Nuclear Proteins / metabolism*
  • Nuclear Proteins / radiation effects*
  • Protein Binding / radiation effects
  • Protein Kinases / radiation effects
  • Retinoblastoma Protein / radiation effects
  • Retinoblastoma-Binding Protein 1
  • Transcription Factor DP1
  • Transcription Factors / metabolism*
  • Tumor Cells, Cultured
  • Tunicamycin / metabolism
  • Ultraviolet Rays

Substances

  • Antibodies, Monoclonal
  • Antigens, Nuclear
  • Carrier Proteins
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • E2F Transcription Factors
  • E2F1 Transcription Factor
  • E2F1 protein, human
  • Enzyme Inhibitors
  • Indolizines
  • Nuclear Proteins
  • Retinoblastoma Protein
  • Retinoblastoma-Binding Protein 1
  • Transcription Factor DP1
  • Transcription Factors
  • Tunicamycin
  • Protein Kinases
  • DNA Helicases
  • XRCC5 protein, human
  • Xrcc6 protein, human
  • Ku Autoantigen
  • castanospermine