Upstream regions of the estrogen receptor alpha proximal promoter transcript regulate ER protein expression through a translational mechanism.
Mol Cell Endocrinol
; 229(1-2): 83-94, 2005 Jan 14.
Article
en En
| MEDLINE
| ID: mdl-15607532
ABSTRACT
Estrogen receptor alpha (ER) mRNA is primarily transcribed from two promoters, the two transcripts share identical sequence encoding the same ER protein but differ in upstream regions. The 5' region of the two transcripts contain upstream open reading frames (uORFs) encoding potential peptides of 20 and 18 amino acids. The peptides have five C-terminal residues in common. These studies were undertaken to determine if the uORFs and encoded peptides differentially affected expression of ER. Expression of green fluorescent protein (GFP) reporter constructs containing upstream proximal promoter transcript sequences with the first 18 codons of ER fused to GFP was tested in HeLa cells. The cells expressed reduced levels of GFP as compared to the pEGFP-N1 parent vector; the effect was dependent on the presence of an intact proximal ER transcript uORF. Similar regulation by the uORF was seen in transfected MCF-7, MDA MB-231 and Ishikawa cells. Only protein expression was affected by eliminating the uORF; RNA levels were unchanged. This indicates the mechanism is translational rather than being an effect of the introduced point mutations on either mRNA stability or transcription. Eliminating the uORF did not significantly increase expression from similar distal promoter transcript ER-GFP constructs. However, study of in-frame fusions of GFP to the entire proximal and distal uORFs and to their translational start motifs showed that the translational start region of the distal uORF was inherently better at initiating translation than the AUG environment of the proximal promoter transcript uORF. The data indicate there are regulatory properties suppressing expression from the ER translation start which are specific to the unique regions of the ER proximal promoter transcript and these are likely associated with the proximal transcript uORF peptide product.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Biosíntesis de Proteínas
/
Regulación Neoplásica de la Expresión Génica
/
Sistemas de Lectura Abierta
/
Regiones Promotoras Genéticas
/
Regiones no Traducidas 5'
/
Receptor alfa de Estrógeno
Límite:
Humans
Idioma:
En
Revista:
Mol Cell Endocrinol
Año:
2005
Tipo del documento:
Article
País de afiliación:
Estados Unidos