Glucose-dependent insulinotropic polypeptide activates the Raf-Mek1/2-ERK1/2 module via a cyclic AMP/cAMP-dependent protein kinase/Rap1-mediated pathway.
J Biol Chem
; 277(40): 37088-97, 2002 Oct 04.
Article
em En
| MEDLINE
| ID: mdl-12138104
ABSTRACT
The gastrointestinal hormone, glucose-dependent insulinotropic polypeptide (GIP), is one of the most important regulators of insulin secretion following ingestion of a meal. GIP stimulates insulin secretion from the pancreatic beta-cell via its G protein-coupled receptor activation of adenylyl cyclase and other signal transduction pathways, but there is little known regarding subsequent protein kinase pathways that are activated. A screening technique was used to determine the relative abundance of 75 protein kinases in CHO-K1 cells expressing the GIP receptor and in two pancreatic beta-cell lines (betaTC-3 and INS-1 (832/13) cells). This information was used to identify kinases that are potentially regulated following GIP stimulation, with a focus on GIP regulation of the ERK1/2 MAPK pathway. In CHO-K1 cells, GIP induced phosphorylation of Raf-1 (Ser-259), Mek1/2 (Ser-217/Ser-221), ERK1/2 (Thr-202 and Tyr-204), and p90 RSK (Ser-380) in a concentration-dependent manner. Activation of ERK1/2 was maximal at 4 min and was cAMP-dependent protein kinase-dependent and protein kinase C-independent. Studies using a beta-cell line (INS-1 clone 832/13) corroborated these findings, and it was also demonstrated that the ERK1/2 module could be activated by GIP in the absence of glucose. Finally, we have shown that GIP regulation of the ERK1/2 module is via Rap1 but does not involve Gbetagamma subunits nor Src tyrosine kinase, and we propose that cAMP-based regulation occurs via B-Raf in both CHO-K1 and beta-cells. These results establish the importance of GIP in the cellular regulation of the ERK1/2 module and identify a role for cAMP in coupling its G protein-coupled receptors to ERK1/2 activity in pancreatic beta-cells.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas Tirosina Quinases
/
Polipeptídeo Inibidor Gástrico
/
Proteínas Serina-Treonina Quinases
/
Proteínas Quinases Dependentes de AMP Cíclico
/
AMP Cíclico
/
Proteína Quinase 1 Ativada por Mitógeno
/
Proteínas Proto-Oncogênicas c-raf
/
Proteínas rap1 de Ligação ao GTP
/
Quinases de Proteína Quinase Ativadas por Mitógeno
/
Proteínas Quinases Ativadas por Mitógeno
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Canadá