The specific activation of gadd45 following UVB radiation requires the POU family gene product N-oct3 in human melanoma cells.
Here we report the specific regulation of gadd45 expression in human melanoma cell lines following UVB radiation. This solar wavelength is likely to be involved in melanoma aetiology. We have previously shown that gadd45 expression is strongly enhanced in a p53-independent manner following UVB irradiation, unlike the other p53 target genes studied. Furthermore, gadd45 is specifically activated in melanocytes since its induction in response to UVB, is not observed in other skin cells such as keratinocytes or fibroblasts. To investigate this particular regulation of gadd45, we analysed the UVB-induced response of different gadd45 promoter regions. Thus, a minimal promoter region of 50 bp length, responsible for gadd45 activation in melanoma cell lines following UVB irradiation, was determined. In electrophoretic mobility shift assays (EMSAs), we showed that this region (-106/-56) of the gadd45 promoter which contains two identical octamers, binds the POU family gene products oct-1 and N-oct3. Given the specific expression pattern of N-oct3 in melanocyte, we invalidated the expression of this transcription factor in melanoma cells: such an abrogation of N-oct3 protein expression in melanoma cells impeded gadd45 UVB-response. Thus the response of melanocyte to UVB may use an original and previously undescribed pathway.
Lefort
K
K
INSERM U453, Centre Léon Bérard, 28 rue Laënnec, 69373 LYON cedex 08, France.
Rouault
J P
JP
Tondereau
L
L
Magaud
J P
JP
Doré
J F
JF
D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects*; D018390:Gene Targeting; D017930:Genes, Reporter; D018398:Homeodomain Proteins; D051863:Host Cell Factor C1; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects; D008544:Melanocytes / Q000378:metabolism / Q000528:radiation effects*; D008545:Melanoma / Q000235:genetics / Q000473:pathology*; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D050811:Octamer Transcription Factor-1; D050809:POU Domain Factors; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics; D017384:Sequence Deletion; D012878:Skin Neoplasms / Q000235:genetics / Q000473:pathology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000528:radiation effects; D014466:Ultraviolet Rays / Q000009:adverse effects; D000097642:GADD45 Proteins
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051863:Host Cell Factor C1; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009363:Neoplasm Proteins; D050811:Octamer Transcription Factor-1; D050809:POU Domain Factors; D011506:Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D000097642:GADD45 Proteins; C497692:HCFC1 protein, human; C494165:POU2F1 protein, human; C085076:transcription factor Brn-2