Acute attenuation of translation initiation and protein synthesis by glucocorticoids in skeletal muscle.
Am J Physiol Endocrinol Metab
; 278(1): E76-82, 2000 Jan.
Article
em En
| MEDLINE
| ID: mdl-10644539
ABSTRACT
Glucocorticoids are diabetogenic factors that not only antagonize the action of insulin in target tissues but also render these tissues catabolic. Therefore, in rats, we endeavored to characterize the effects in skeletal muscle of glucocorticoids on translation initiation, a regulated process that, in part, governs overall protein synthesis through the modulated activities of eukaryotic initiation factors (eIFs). Four hours after intraperitoneal administration of dexamethasone (100 microg/100 g body wt), protein synthesis in skeletal muscle was reduced to 59% of the value recorded in untreated control animals. Furthermore, translation initiation factor eIF4E preferred association with its endogenous inhibitor 4E-BP1 rather than eIF4G. Dexamethasone treatment resulted in dephosphorylation of both 4E-BP1 and the 40S ribosomal protein S6 kinase concomitant with enhanced phosphorylation of eIF4E. Moreover, the guanine nucleotide exchange activity of eIF2B was unaffected as was phosphorylation of the alpha-subunit of eIF2. Hence glucocorticoids negatively modulate the activation of a subset of the protein synthetic machinery, thereby contributing to the catabolic properties of this class of hormones in vivo.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Biossíntese de Proteínas
/
Dexametasona
/
Proteínas de Transporte
/
Glucocorticoides
/
Proteínas Musculares
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol Endocrinol Metab
Assunto da revista:
ENDOCRINOLOGIA
/
FISIOLOGIA
/
METABOLISMO
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Estados Unidos