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Epinephrine and insulin stimulate different mitogen-activated protein kinase signaling pathways in rat skeletal muscle.
Napoli, R; Gibson, L; Hirshman, M F; Boppart, M D; Dufresne, S D; Horton, E S; Goodyear, L J.
Afiliação
  • Napoli R; Research Division, Joslin Diabetes Center, and Harvard Medical School, Boston, Massachusetts 02215, USA.
Diabetes ; 47(10): 1549-54, 1998 Oct.
Article em En | MEDLINE | ID: mdl-9753291
ABSTRACT
Little is known about the regulation of the mitogen-activated protein (MAP) kinase signaling cascades by hormonal stimulation in vivo. The extracellular signal-regulated kinase (ERK) and the c-jun kinase (JNK) are two MAP kinase signaling pathways that could play a role in the cellular response to hormones such as insulin and epinephrine. We studied the effects of insulin (20 U/rat) and epinephrine (25 microg/100 g body wt) injected in vivo on ERK and JNK signaling in skeletal muscle from Sprague-Dawley rats. Insulin significantly increased ERK phosphorylation and the activity of its downstream substrate, the p90 ribosomal S6 kinase 2 (RSK2), by 1.4-fold, but it had no effect on JNK activity. In contrast, epinephrine had no effect on ERK phosphorylation or RSK2 activity, but it increased JNK activity by twofold, an effect that was inhibited by the presence of combined alpha and beta blockade. Furthermore, the phosphorylation of both p46 and p55 isoforms of JNK, measured by phosphospecific antibody, was increased severalfold. The activity and phosphorylation of MAP kinase kinase (MKK)-4, an upstream regulator of JNK, was unchanged by epinephrine. Incubation of isolated soleus muscles in vitro with epinephrine (10(-5) mol/l) also increased JNK activity by twofold. These data are the first to demonstrate that epinephrine can increase JNK activity. Insulin and epinephrine have different effects on MAP kinase signaling pathways in skeletal muscle, which may be one of the underlying molecular mechanisms through which these hormones regulate opposing metabolic functions.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Transdução de Sinais / Epinefrina / Proteínas Quinases Dependentes de Cálcio-Calmodulina / Músculo Esquelético / Quinases de Proteína Quinase Ativadas por Mitógeno / Proteínas Quinases JNK Ativadas por Mitógeno / Insulina Limite: Animals Idioma: En Revista: Diabetes Ano de publicação: 1998 Tipo de documento: Article País de afiliação: Estados Unidos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Transdução de Sinais / Epinefrina / Proteínas Quinases Dependentes de Cálcio-Calmodulina / Músculo Esquelético / Quinases de Proteína Quinase Ativadas por Mitógeno / Proteínas Quinases JNK Ativadas por Mitógeno / Insulina Limite: Animals Idioma: En Revista: Diabetes Ano de publicação: 1998 Tipo de documento: Article País de afiliação: Estados Unidos