@entity1425 and insulin stimulate different mitogen-activated protein kinase signaling pathways in XXXX skeletal muscle.

@entity70715 @entity1425 @entity2509 @entity6336 @entity21680 @entity35
Little is known about the regulation of the mitogen-activated protein (MAP) kinase signaling cascades by hormonal stimulation in vivo. The @entity2509 ( @entity2509 ) and the @entity6336 ( @entity6336 ) are two MAP kinase signaling pathways that could play a role in the cellular response to hormones such as insulin and @entity1425 . We studied the effects of insulin (20 U/ @entity35 ) and @entity1425 (25 microg/100 g body wt) injected in vivo on @entity2509 and @entity6336 signaling in skeletal muscle from @entity35 . Insulin significantly increased @entity2509 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 @entity6336 activity. In contrast, @entity1425 had no effect on @entity2509 phosphorylation or RSK2 activity, but it increased @entity6336 activity by twofold, an effect that was inhibited by the presence of combined alpha and beta blockade. Furthermore, the phosphorylation of both p46 and @entity70715 isoforms of @entity6336 , measured by phosphospecific antibody, was increased severalfold. The activity and phosphorylation of MAP kinase kinase ( @entity21680 , an upstream regulator of @entity6336 , was unchanged by @entity1425 . Incubation of isolated soleus muscles in vitro with @entity1425 (10(-5) mol/l) also increased @entity6336 activity by twofold. These data are the first to demonstrate that @entity1425 can increase @entity6336 activity. Insulin and @entity1425 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.
