Wortmannin inhibits insulin-stimulated activation of protein phosphatase 1 in rat cardiomyocytes.
Am J Physiol
; 276(5): H1520-6, 1999 05.
Article
em En
| MEDLINE
| ID: mdl-10330234
ABSTRACT
A major function of insulin in target tissues is the activation of glycogen synthase. Phosphatidylinositol 3-kinase (PI3K) has been implicated in the insulin-induced activation of glycogen synthase, although the true function of this enzyme remains unclear. Data presented here demonstrate that the PI3K inhibitors wortmannin and LY-294002 block the insulin-stimulated activation of protein phosphatase 1 (PP1) in rat ventricular cardiomyocytes. This loss of phosphatase activation mimics that seen in diabetic cardiomyocytes, in which insulin stimulation fails to activate both PP1 and glycogen synthase. Interestingly, in diabetic cells, insulin stimulated PI3K activity to 300% of that in untreated controls, whereas this activity was increased by only 77% in normal cells. PI3K protein levels, however, were similar in normal and diabetic cells. Our results indicate that PI3K is involved in the stimulation of glycogen synthase activity by insulin through the regulation of PP1. The inability of insulin to stimulate phosphatase activity in diabetic cells, despite a significant increase in PI3K activity, suggests a defect in the insulin signaling pathway that contributes to the pathology of insulin-dependent diabetes.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfoproteínas Fosfatases
/
Inibidores Enzimáticos
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Hipoglicemiantes
/
Androstadienos
/
Insulina
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Miocárdio
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Estados Unidos