Transcription factor AP1 is involved in basal and okadaic acid-stimulated activity of the human PRL promoter.
The tumor promoter, okadaic acid (OA), an inhibitor of protein phosphatases, stimulates the activity of the human PRL (hPRL) proximal promoter. We analyzed in detail the effects of OA on transcription factor binding to elements P1 and P2 of this promoter, sequences known to contain at least one Pit-1 binding site each. OA treatment induces binding of an AP1-related transcription factor to the P1 site. This effect is specific, as protein binding to the P2 site is not altered by the treatment. Specific antibodies were used to confirm that the OA-induced complex is related to AP1 and to show that it contains JunD and c-fos, but not Pit-1. The increase in AP1 binding to P1 and to a canonical AP1 site correlates to an increase in cellular JunD and c-fos content. Transient transfection experiments showed that both AP1 and Pit-1 are involved in the regulation of basal and OA-stimulated promoter activity. Our results demonstrate that a member of the AP1 family, containing JunD and c-fos, can bind to the proximal element P1 within the hPRL promoter. In addition, they show that AP1 is involved in both basal and OA-stimulated expression of the hPRL gene.
Caccavelli
L
L
Laboratoire d'immunopathologie, INSERM U430 Hopital Broussais, Paris, France.
Manfroid
I
I
Martial
J A
JA
Muller
M
M
D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004268:DNA-Binding Proteins / Q000276:immunology / Q000378:metabolism; D051863:Host Cell Factor C1; D006801:Humans; D008156:Luciferases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D019319:Okadaic Acid / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011388:Prolactin / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000276:immunology / Q000378:metabolism; D014162:Transfection
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494187:POU1F1 protein, human; C494165:POU2F1 protein, human; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D019319:Okadaic Acid; D011388:Prolactin; D008156:Luciferases; D010749:Phosphoprotein Phosphatases