Identification of cAMP-dependent kinase as a third in vivo ribosomal protein S6 kinase in pancreatic beta-cells.
J Mol Biol
; 389(3): 480-94, 2009 Jun 12.
Article
em En
| MEDLINE
| ID: mdl-19376132
ABSTRACT
Ribosomal protein S6 (rpS6) is phosphorylated in vivo by isoforms of p70 S6 protein kinase and p90 ribosomal S6 kinase, and there is good evidence that it plays a positive role in controlling pancreatic beta-cell size and function. In this report, we demonstrate in the pancreatic beta-cell line MIN6 (mouse insulinoma cell line 6) and islets of Langerhans that agents which stimulate increases in cAMP, such as glucagon-like peptide-1 and forskolin, lead to the phosphorylation of rpS6 at Ser235/Ser236 independently of the activation of the currently known in vivo rpS6 kinases via a pathway that is sensitive to inhibitors of cAMP-dependent protein kinase [protein kinase A (PKA)]. This cAMP-dependent rpS6 kinase activity is also sensitive to PKI in vitro, and PKA exclusively phosphorylates recombinant rpS6 on Ser235/Ser236 in vitro. With these data taken together, we conclude that PKA can phosphorylate rpS6 exclusively at Ser235/Ser236 in vivo in pancreatic beta-cells, thus providing a potentially important link between cAMP signalling and the regulation of protein synthesis. Lastly, we provide evidence that PKA is also likely to phosphorylate rpS6 on Ser235/Ser236 in vivo in a number of other mammalian cell types.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Quinases Dependentes de AMP Cíclico
/
Proteínas Quinases S6 Ribossômicas
/
Células Secretoras de Insulina
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Mol Biol
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Reino Unido