Affiliation:
1. From the Department of Biochemistry and Molecular Biology and the Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana
Abstract
Glycogen is an important component of whole-body glucose metabolism. MGSKO mice lack skeletal muscle glycogen due to disruption of the GYS1 gene, which encodes muscle glycogen synthase. MGSKO mice were 5–10% smaller than wild-type littermates with less body fat. They have more oxidative muscle fibers and, based on the activation state of AMP-activated protein kinase, more capacity to oxidize fatty acids. Blood glucose in fed and fasted MGSKO mice was comparable to wild-type littermates. Serum insulin was lower in fed but not in fasted MGSKO animals. In a glucose tolerance test, MGSKO mice disposed of glucose more effectively than wild-type animals and had a more sustained elevation of serum insulin. This result was not explained by increased conversion to serum lactate or by enhanced storage of glucose in the liver. However, glucose infusion rate in a euglycemic-hyperinsulinemic clamp was normal in MGSKO mice despite diminished muscle glucose uptake. During the clamp, MGSKO animals accumulated significantly higher levels of liver glycogen as compared with wild-type littermates. Although disruption of the GYS1 gene negatively affects muscle glucose uptake, overall glucose tolerance is actually improved, possibly because of a role for GYS1 in tissues other than muscle.
Publisher
American Diabetes Association
Subject
Endocrinology, Diabetes and Metabolism,Internal Medicine
Reference52 articles.
1. Preiss J, Walsh DA: The comparative biochemistry of glycogen and starch. In Biology of Carbohydrates. Ginsburg V, Robbins P, Eds. New York, John Wiley,1981, p.199–314
2. Kaslow HR, Lesikar DD, Antwi D, Tan AW: L-type glycogen synthase: tissue distribution and electrophoretic mobility. J Biol Chem 260:9953–9956,1985
3. Kaslow HR, Lesikar DD: Isozymes of glycogen synthase. FEBS Lett 172:294–298,1984
4. Meyer C, Dostou JM, Welle SL, Gerich JE: Role of human liver, kidney, and skeletal muscle in postprandial glucose homeostasis. Am J Physiol Endocrinol Metab 282:E419–E427,2002
5. Jue T, Rothman DL, Shulman GI, Tavitian BA, DeFronzo RA, Shulman RG: Direct observation of glycogen synthesis in human muscle with 13C NMR. Proc Natl Acad Sci U S A 86:4489–4491,1989
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