Functional antagonism between RNA binding proteins HuR and CUGBP2 determines the fate of COX-2 mRNA translation.
Gastroenterology
; 132(3): 1055-65, 2007 Mar.
Article
en En
| MEDLINE
| ID: mdl-17383427
ABSTRACT
BACKGROUND AND AIMS:
Cyclooxygenase-2 (COX-2) expression is regulated at the levels of messenger RNA (mRNA) stability and translation by AU-rich elements (ARE) located in its 3' untranslated region (3'UTR). Although structurally homologous RNA binding proteins HuR and CUGBP2 stabilize COX-2 mRNA, HuR induces whereas CUGBP2 inhibits COX-2 mRNA translation. This study aimed to determine the antagonism between these proteins on COX-2 expression.METHODS:
COX-2 ARE binding activity was determined by nitrocellulose filter binding and UV cross-linking assays using recombinant glutathione S-transferase (GST)/HuR and GST/CUGBP2. Proteinprotein interactions were determined by GST pull-down, yeast 2-hybrid, and immunocytochemistry assays. Nucleocytoplasmic shutting was determined by heterokaryon analyses. The effect of CUGBP2 and HuR on COX-2 ARE-dependent translation was shown by a chimeric luciferase mRNA containing COX-2 3'UTR. HT-29 cells were subjected to 12 Gy gamma-irradiation in a cesium irradiator.RESULTS:
CUGBP2 and HuR bind with similar affinities to COX-2 ARE, but CUGBP2 competes with HuR for binding. In vitro, HuR and CUGBP2 heterodimerize. Furthermore, FLAG-tagged HuR and myc-tagged CUGBP2 colocalize in the nucleus of HCT-116 cells. Moreover, both proteins shuttled between the nucleus and cytoplasm. In vitro, HuR enhanced whereas CUGBP2 inhibited translation of the chimeric luciferase COX-2 3'UTR mRNA. Furthermore, CUGBP2 competitively inhibited HuR-mediated translation of the transcript. In HT-29 cells transfected with HuR and CUGBP2, a switch in COX-2 mRNA binding from predominantly HuR to CUGBP2 occurred after radiation treatment, which was coupled with increased silencing of the COX-2 mRNA.CONCLUSIONS:
CUGBP2 overrides HuR and suppresses COX-2 mRNA translation.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Biosíntesis de Proteínas
/
ARN Mensajero
/
Proteínas de Unión al ARN
/
Regiones no Traducidas 3'
/
Ciclooxigenasa 2
/
Proteínas de la Membrana
/
Antígenos de Superficie
/
Proteínas del Tejido Nervioso
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Gastroenterology
Año:
2007
Tipo del documento:
Article
País de afiliación:
Estados Unidos