Okadaic acid stimulated TRE binding activity in a papilloma producing mouse keratinocyte cell line involves increased AP-1 expression.
The effects of the non-phorbol ester type tumor promoter okadaic acid, a serine-threonine phosphatase inhibitor, on activator protein 1 (AP-1) DNA binding activity were studied in papilloma producing 308 mouse keratinocytes. Okadaic acid increased AP-1 binding to a consensus TPA responsive element (TRE) within 2 h; maximum stimulation was observed at 6 h followed by a gradual decrease to basal levels within 24 h. Jun B, Jun D and Fos B proteins were identified as the major components of the AP-1 complex binding to the TRE element at 6 h. Inhibition of transcription with actinomycin D and inhibition of protein synthesis with cycloheximide abrogated the okadaic acid effect on AP-1 DNA binding, indicating that transcription and translation are required for okadaic acid increased TRE binding activity. Northern and Western blot analyses revealed a correlation between increased AP-1 binding activity and accumulation of jun B, jun D and fos B mRNAs and proteins. These data suggest increased AP-1 expression as principal mechanism of okadaic acid stimulated AP-1 activation in the mouse keratinocytes studied.
Rosenberger
S F
SF
Department of Radiation Oncology, The University of Arizona Health Sciences Center, Tucson 85724, USA.
Bowden
G T
GT
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002273:Carcinogens / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004988:Ethers, Cyclic / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D015603:Keratinocytes; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D019319:Okadaic Acid; D014176:Protein Biosynthesis / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D000071701:Regulatory Factor X Transcription Factors; D015534:Trans-Activators / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D002273:Carcinogens; D004268:DNA-Binding Proteins; D004988:Ethers, Cyclic; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D003609:Dactinomycin; D019319:Okadaic Acid; D004247:DNA; D003513:Cycloheximide; D004121:Dimethyl Sulfoxide