Novel intronic promoter in the rat ER alpha gene responsible for the transient transcription of a variant receptor.
Endocrinology
; 142(9): 4106-19, 2001 Sep.
Article
em En
| MEDLINE
| ID: mdl-11517190
ABSTRACT
To analyze the molecular origin of an ER variant, the truncated ER product-1, transiently expressed at the proestrus in lactotrope cells, we generated a 2.5-kb sequence of a genomic region upstream and downstream the specific sequence truncated ER product-1. Genomic Southern blot analysis showed that truncated ER product-1 is spliced from a noncoding leader exon localized within the intron 4 of the ER alpha gene. Analysis of the promoter sequence revealed the presence of a major transcriptional start site, a canonical TATA box and putative cis regulatory elements for pituitary specific expression as well as an E-responsive element. In transient transfection, the truncated ER product-1 promoter was transcriptionally the most active in the lactotrope cell lines (MMQ). Analysis of truncated ER product-1 functionality showed that 1) the protein inhibited ER alpha binding to the E-responsive element in electromobility shift assays, 2) inhibited the E2 binding to ER alpha in binding assays, 3) the truncated ER product-1/ER alpha complex antagonized the transcriptional activity elicited by E2, 4) nuclear localization of green fluorescent protein-ER alpha was altered in Chinese hamster ovary cell lines stably expressing truncated ER product-1. Collectively, these data demonstrated that the protein exerts full dominant negative activity against ER alpha. Moreover, truncated ER product-1/ER alpha complex also repressed the activity of all promoters tested to date, suggesting a general inhibitory effect toward transcription. In conclusion, the data suggest that truncated ER product-1 could regulate estrogen signaling via a specific promoter in lactotrope cells.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Transcrição Gênica
/
Variação Genética
/
Receptores de Estrogênio
/
Regiões Promotoras Genéticas
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2001
Tipo de documento:
Article