Reduced AMP-activated protein kinase activity in mouse skeletal muscle does not exacerbate the development of insulin resistance with obesity

• Published in: Diabetologia Vol. 52; no. 11; pp. 2395 - 2404
• Main Authors: Beck Jørgensen, S, O'Neill, H. M, Hewitt, K, Kemp, B. E, Steinberg, G. R
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.11.2009; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Aminoimidazole Carboxamide - analogs & derivatives; Aminoimidazole Carboxamide - metabolism; Animals; Biological and medical sciences; Biosynthesis; Body Weight; Deoxyglucose - metabolism; Diabetes; Diabetes. Impaired glucose tolerance; Diet; Dietary Fats - pharmacology; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Fatty acids; Fundamental and applied biological sciences. Psychology; Glucose; Human Physiology; Insulin resistance; Insulin Resistance - physiology; Internal Medicine; Kinases; Kinetics; Lipid Peroxidation - physiology; Lipids; Lipids - physiology; Male; Medical sciences; Medicine; Medicine & Public Health; Metabolic Diseases; Mice; Mice, Inbred C57BL; Mice, Transgenic; Muscle, Skeletal - enzymology; Muscle, Skeletal - metabolism; Musculoskeletal system; Obesity; Obesity - enzymology; Obesity - physiopathology; Oxidation; Phosphorylation; Physiology; Protein Kinases - genetics; Protein Kinases - metabolism; Proteins; Reference Values; Ribonucleotides - metabolism; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system; Australia; HOMA-IR; Obesity; Mouse; 5′-AMP-activated protein kinase; High-fat diet; AMPK; Insulin resistance; Acetyl-CoA carboxylase-2; Skeletal muscle; ACC2; Endocrinopathy; Non-specific serine/threonine protein kinase; Acetyl-CoA carboxylase; Ligases; Development; Nutritional status; Carbon-carbon ligases; AMPK· High-fat diet; Enzyme; Transferases; Diabetes mellitus; Rodentia; Nutrition disorder; Metabolic diseases; Striated muscle; 5'-AMP-activated protein kinase; Feeding; Target tissue resistance; Vertebrata; Mammalia; Diet; Animal; HOMA- IR
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-009-1483-8

Aims/hypothesis Obesity-related insulin resistance is associated with accumulation of bioactive lipids in skeletal muscle. The AMP-activated protein kinase (AMPK) regulates lipid oxidation in muscle by inhibiting acetyl-CoA carboxylase-2 (ACC2) and increasing mitochondrial biogenesis. We investigated whether reduced levels of muscle AMPK promote lipid accumulation and insulin resistance during high-fat feeding. Methods Male C57/BL6 wild-type mice and transgenic littermates overexpressing an α2AMPK kinase-dead (KD) in muscle were fed control or high-fat diet. Whole-body glucose homeostasis was assessed by glucose and insulin tolerance tests, and by measuring fasting and fed serum insulin and glucose. Insulin action in muscle was determined by measuring 2-deoxy-[³H]glucose uptake and Akt phosphorylation in incubated soleus and extensor digitorum longus muscles. Muscle triacylglycerol, diacylglycerol and ceramide content was measured by thin-layer chromatography. Mitochondrial proteins were measured by immunoblotting. Results KD mice had reduced skeletal muscle α2AMPK activity (50% in gastrocnemius and >80% in soleus and extensor digitorum longus) and ACC2 Ser228 phosphorylation (90% in gastrocnemius). High-fat feeding increased body mass and adiposity, and impaired insulin and glucose tolerance; however, there were no differences between wild-type and KD littermates. High-fat feeding impaired insulin-stimulated muscle glucose uptake and Akt-phosphorylation, while increasing muscle triacylglycerol, diacylglycerol (p = 0.07) and ceramide, but these effects were not exacerbated in KD mice. In response to high-fat feeding, mitochondrial proteins were increased to similar levels in wild-type and KD muscles. Conclusions/interpretation Obesity-induced lipid accumulation and insulin resistance were not exacerbated in AMPK KD mice, suggesting that reduced levels of muscle α2AMPK do not promote insulin resistance in the early phase of obesity-related diabetes.