Calreticulin interacts with C/EBPalpha and C/EBPbeta mRNAs and represses translation of C/EBP proteins.
Mol Cell Biol
; 22(20): 7242-57, 2002 Oct.
Article
en En
| MEDLINE
| ID: mdl-12242300
We previously identified an RNA binding protein, CUGBP1, which binds to GCN repeats located within the 5' region of C/EBPbeta mRNAs and regulates translation of C/EBPbeta isoforms. To further investigate the role of RNA binding proteins in the posttranscriptional control of C/EBP proteins, we purified additional RNA binding proteins that interact with GC-rich RNAs and that may regulate RNA processing. In HeLa cells, the majority of GC-rich RNA binding proteins are associated with endogenous RNA transcripts. The separation of these proteins from endogenous RNA identified several proteins in addition to CUGBP1 that specifically interact with the GC-rich 5' region of C/EBPbeta mRNA. One of these proteins was purified to homogeneity and was identified as calreticulin (CRT). CRT is a multifunctional protein involved in several biological processes, including interaction with and regulation of rubella virus RNA processing. Our data demonstrate that both CUGBP1 and CRT interact with GCU repeats within myotonin protein kinase and with GCN repeats within C/EBPalpha and C/EBPbeta mRNAs. GCN repeats within these mRNAs form stable SL structures. The interaction of CRT with SL structures of C/EBPbeta and C/EBPalpha mRNAs leads to inhibition of translation of C/EBP proteins in vitro and in vivo. Deletions or mutations abolishing the formation of SL structures within C/EBPalpha and C/EBPbeta mRNAs lead to a failure of CRT to inhibit translation of C/EBP proteins. CRT-dependent inhibition of C/EBPalpha is sufficient to block the growth-inhibitory activity of C/EBPalpha. This finding further defines the molecular mechanism for posttranscriptional regulation of the C/EBPalpha and C/EBPbeta proteins.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Represoras
/
Ribonucleoproteínas
/
Biosíntesis de Proteínas
/
Proteínas de Unión al Calcio
/
ARN Mensajero
/
Proteínas de Unión al ARN
/
Proteína alfa Potenciadora de Unión a CCAAT
/
Proteína beta Potenciadora de Unión a CCAAT
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Mol Cell Biol
Año:
2002
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos