Regulatory regions in the promoter and third intron of the growth hormone gene in rainbow trout, Oncorhynchus mykiss walbaum.
The mechanisms involved in the transcriptional regulation of the rainbow trout (Oncorhynchus mykiss) growth hormone (tGH) gene have been investigated. Transient transfection assays, using deletion mutants of the tGH promoter, demonstrated that the -226/+24 5'-flanking region, bearing three binding sites for the pituitary-specific transcription factor GHF1/Pit1 and a cAMP-response element, is necessary and sufficient to confer strong tissue-specific and cAMP-stimulated expression to a luciferase reporter gene. This region is also upregulated by the synthetic glucocorticoid dexamethasone (DEX), the combined effects of cAMP, and DEX being synergistic. Footprinting and gel shift assays revealed that GHF1 binds to a recognition element in the third intron of the tGH gene, suggesting that GHF1 can affect the expression of this gene by interacting with response elements in the transcription unit. These results may be exploited to design tGH gene constructs for the production of autotransgenic fish, in which the expression of the isospecific transgene driven by a constitutive proximal promoter is specifically targeted to the pituitary and physiologically controlled.
Bernardini
S
S
Dipartimento di Biologia, Universit¿a di Padova, Via Bassi 58/B, Padova, I-35131, Italy.
Argenton
F
F
Vianello
S
S
Colombo
L
L
Bortolussi
M
M
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D000242:Cyclic AMP / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004357:Drug Synergism; D017353:Gene Deletion; D005938:Glucocorticoids / Q000494:pharmacology; D013006:Growth Hormone / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017686:Oncorhynchus mykiss / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000378:metabolism / Q000494:pharmacology; D014162:Transfection
D004268:DNA-Binding Proteins; D005938:Glucocorticoids; C494187:POU1F1 protein, human; C494186:Pou1f1 protein, rat; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D003907:Dexamethasone; D013006:Growth Hormone; D000242:Cyclic AMP