The tilapia prolactin I gene: evolutionary conservation of the regulatory elements directing pituitary-specific expression.
DNA Cell Biol
; 15(8): 679-92, 1996 Aug.
Article
em En
| MEDLINE
| ID: mdl-8769570
ABSTRACT
To study the elements involved in the pituitary specific transcriptional regulation of the tilapia prolactin I gene (tiPRL I), we have cloned and entirely sequenced a 3.4-kb genomic fragment immediately upstream from the first exon. In footprinting experiments, three tilapia sequences are protected from DNase I digestion by rat pituitary extracts (base pair coordinates -643 to -593, -160 to -111, and -73 to -46). Computer analysis of the nucleotide sequence reveals significant homology to mammalian binding sites for Pit-1, a transcription factor that is known to mediate pituitary-specific expression of the PRL genes in mammals. The tiPRL I 5'-flanking sequences can direct transient expression of a linked luciferase reporter gene in transfected rat pituitary cell lines and tilapia pituitary primary cell cultures. Transient expression experiments with 5'-deletion mutants reveal three regulatory regions. Two have a stimulatory effect on transcription and one an inhibitory effect. Electrophoretic mobility-shift assays (EMSA) demonstrate that the rat Pit-1 factor specifically binds to tilapia DNA sequences. Several such tilapia Pit-1 binding sites mediate activation of a linked heterologous promoter in transfected rat and tilapia pituitary cells. As evidenced by EMSA, a Pit-1-like protein is present in tilapia pituitary extracts. All these data point to a high conservation of the molecular mechanisms involved in pituitary-specific expression of the PRL genes in vertebrates.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Hipófise
/
Prolactina
/
Sequências Reguladoras de Ácido Nucleico
/
Regulação da Expressão Gênica
/
Tilápia
Limite:
Animals
Idioma:
En
Revista:
DNA Cell Biol
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Bélgica