The effects of insulin on enzymes involved in regulation of glycogen synthesis were investigated in the perfused rat heart. In hearts from normal fed rats, perfusion with insulin (10m8 M) for 5, 10, and 15 min resulted in a 100% increase in the activity of the I (glucose 6-phosphate-independent) form of glycogen synthase. Glycogen synthase activity was completely unresponsive to insulin when he...

After a single bout of exercise, insulin action is increased in the muscles that were active during exercise. The increased insulin action has been shown to involve glucose transport, glycogen synthesis, and glycogen synthase (GS) activation as well as amino acid transport. A major mechanism involved in increased insulin stimulation of glucose uptake after exercise seems to be the exercise-asso...

OBJECTIVE Integrins mediate platelet adhesion and transmit outside-in signals leading to platelet spreading. Phosphoinositide 3-kinases (PI3Ks) play a critical role in outside-in signaling and platelet spreading; however, the mechanisms of PI3K activation and function in outside-in signaling are unclear. We sought to determine the role of the Akt family of serine/threonine kinases and activatio...

Glucagon-like peptide-1 (GLP-1), an incretin with glucose-dependent insulinotropic and insulin-independent antidiabetic properties, has insulin-like effects on glucose metabolism in extrapancreatic tissues participating in overall glucose homeostasis. These effects are exerted through specific receptors not associated with cAMP, an inositol phosphoglycan being a possible second messenger. In ra...

Glucocorticoids cause insulin resistance in skeletal muscle. The aims of the present study were to investigate the effects of contraction on glucose uptake, insulin signaling, and regulation of glycogen synthesis in skeletal muscles from rats treated with the glucocorticoid analog dexamethasone (1 mg x kg(-1) x day(-1) ip for 12 days). Insulin resistance in dexamethasone-treated rats was confir...

AMP-activated protein kinase (AMPK) is proposed to stimulate fat and carbohydrate catabolism to maintain cellular energy status. Recent studies demonstrate that pharmacologic activation of AMPK and mutations in the enzyme are associated with elevated muscle glycogen content in vivo. Our purpose was to determine the mechanism for increased muscle glycogen associated with AMPK activity in vivo. A...

The Ca”-stimulated phosphorylation of rabbit muscle glycogen synthase (EC 2.4.1.11) catalyzed by phosphorylase kinase (EC 2.7.1.38) was characterized and compared with the reaction involving phosphorylase (EC 2.4.1.1). By comparing reaction rates at equal concentrations (on a mass basis), the activity ratio of phosphorylase/synthase varied from 30 (0.05 mg/ml) to approximately 8 (1 mg/ml). A ba...

To identify novel regulators of Wnt signaling, we performed yeast two-hybrid analyses with Dvl-1 and identified BP75 as a candidate. Here, we demonstrated that BP75 directly interacts with Dvl-1 in mammalian cells and enhances TCF-dependent gene expression induced by Dvl-1. In support of these results, BP75 in cooperation with Dvl-1 was found to facilitate dephosphorylation at Tyr216 of glycoge...