Thyrotropin-releasing hormone and epidermal growth factor induce human prolactin expression via identical multiple cis elements.
Pituitary GH3 cells were transfected with different deletion mutants of the human prolactin (hPRL) promoter fused to the CAT reporter gene. The proximal region (-250 to -42) was sufficient to confer stimulation by both thyrotropin-releasing hormone (TRH) and epidermal growth factor (EGF). Further deletion analyses demonstrated the importance of the three proximal Pit-1 binding sites in this response. However, Pit-1 binding oligonucleotides confer neither TRH nor EGF induction to a linked neutral promoter, suggesting that other elements might be involved. We have previously shown that sequence A (-115 to -85) is needed together with Pit-1 binding sites for full cyclic AMP response of hPRL-CAT. Mutation of this sequence strongly affects TRH and EGF induction. On the other hand, three copies of sequence A confer both TRH and EGF response to a linked neutral promoter. In conclusion, although TRH and EGF activate mostly different intracellular pathways, they mediate transcriptional induction of the hPRL promoter via identical cis elements.
Berwaer
M
M
Laboratorie de Biologie Moléculaire et de Génie Génétique, Université de Liège, Sart Tilman, Belgium.
Peers
B
B
Nalda
A M
AM
Monget
P
P
Davis
J R
JR
Belayew
A
A
Martial
J A
JA
D000818:Animals; D001665:Binding Sites; D000242:Cyclic AMP / Q000502:physiology; D004268:DNA-Binding Proteins; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D010911:Pituitary Neoplasms; D011388:Prolactin / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D013937:Thymidine Kinase / Q000235:genetics; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C494187:POU1F1 protein, human; C494186:Pou1f1 protein, rat; D011993:Recombinant Fusion Proteins; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D013973:Thyrotropin-Releasing Hormone; D004815:Epidermal Growth Factor; D011388:Prolactin; D000242:Cyclic AMP; D013937:Thymidine Kinase