Endurance exercise training increases APPL1 expression and improves insulin signaling in the hepatic tissue of diet-induced obese mice, independently of weight loss

• Published in: Journal of cellular physiology Vol. 227; no. 7; pp. 2917 - 2926
• Main Authors: Marinho, R., Ropelle, E.R., Cintra, D.E., De Souza, C.T., Da Silva, A.S.R., Bertoli, F.C., Colantonio, E., D'Almeida, V., Pauli, J.R.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-07-2012
• Subjects: Adaptor Proteins, Signal Transducing - biosynthesis; Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Diabetes Mellitus, Type 2 - genetics; Diabetes Mellitus, Type 2 - metabolism; Diabetes Mellitus, Type 2 - physiopathology; Diet; Forkhead Box Protein O1; Forkhead Transcription Factors - genetics; Forkhead Transcription Factors - metabolism; Gluconeogenesis - genetics; Gluconeogenesis - physiology; Glucose-6-Phosphatase - genetics; Glucose-6-Phosphatase - metabolism; Glycogen - genetics; Glycogen - metabolism; Glycogen Synthase Kinase 3 - genetics; Glycogen Synthase Kinase 3 - metabolism; Glycogen Synthase Kinase 3 beta; Insulin - genetics; Insulin - metabolism; Liver - metabolism; Male; Mice; Mice, Obese; Obesity - etiology; Obesity - genetics; Obesity - metabolism; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Phosphorylation; Physical Conditioning, Animal - physiology; Physical Endurance - physiology; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Signal Transduction; Trans-Activators - genetics; Trans-Activators - metabolism; Transcription Factors; Weight Loss - physiology
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/jcp.23037

Hepatic insulin resistance is the major contributor to fasting hyperglycemia in type 2 diabetes. The protein kinase Akt plays a central role in the suppression of gluconeogenesis involving forkhead box O1 (Foxo1) and peroxisome proliferator‐activated receptor gamma co‐activator 1 alpha (PGC‐1α), and in the control of glycogen synthesis involving the glycogen synthase kinase beta (GSK3β) in the liver. It has been demonstrated that endosomal adaptor protein APPL1 interacts with Akt and blocks the association of Akt with its endogenous inhibitor, tribbles‐related protein 3 (TRB3), improving the action of insulin in the liver. Here, we demonstrated that chronic exercise increased the basal levels and insulin‐induced Akt serine phosphorylation in the liver of diet‐induced obese mice. Endurance training was able to increase APPL1 expression and the interaction between APPL1 and Akt. Conversely, training reduced both TRB3 expression and TRB3 and Akt association. The positive effects of exercise on insulin action are reinforced by our findings that showed that trained mice presented an increase in Foxo1 phosphorylation and Foxo1/PGC‐1α association, which was accompanied by a reduction in gluconeogenic gene expressions (PEPCK and G6Pase). Finally, exercised animals demonstrated increased at basal and insulin‐induced GSK3β phosphorylation levels and glycogen content at 24 h after the last session of exercise. Our findings demonstrate that exercise increases insulin action, at least in part, through the enhancement of APPL1 and the reduction of TRB3 expression in the liver of obese mice, independently of weight loss. J. Cell. Physiol. 227: 2917–2926, 2012. © 2011 Wiley Periodicals, Inc.