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Isolation of Primary Mouse Hepatocytes for Nascent Protein Synthesis Analysis by Non-radioactive L-azidohomoalanine Labeling Method
Published on: October 23, 2018
cAMP inhibits the insulin-stimulated mitogen-activated protein kinase pathway in rat hepatoma H4EII cells
Y Nagasaka1, K Kaku, K Nakamura
1Department of Biochemistry, Yamaguchi University School of Medicine, Japan.
Abstract:
Effects of cAMP on insulin-stimulated mitogen-activated protein (MAP) kinase pathway were examined using rat hepatoma H4EII cells. MAP kinase was rapidly activated and reached a peak 3 min after the stimulation by insulin. Forskolin (1 microM) and 8(4-chlorophenylthio)cAMP (8-CPT-cAMP) (0.1 mM) inhibited the insulin-stimulated MAP kinase activity. Pretreatment of the cells with H-8 (50 microM), a cAMP-dependent protein kinase inhibitor, enhanced the insulin-stimulated MAP kinase activity and partially restored the inhibitory effect of cAMP. Furthermore, insulin-induced phosphorylation of MAP kinase was inhibited by 8-CPT-cAMP, and the inhibition was restored by H-8. 8-CPT-cAMP did not inhibit the autophosphorylation of insulin receptor. These data indicate that elevation of intracellular cAMP blocks the insulin-stimulated MAP kinase pathway downstream of insulin receptor.
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