Acute exercise reduces hepatic glucose production through inhibition of the Foxo1/HNF-4alpha pathway in insulin resistant mice.
Protein hepatocyte nuclear factor 4alpha (HNF-4alpha) is atypically activated in the liver of diabetic rodents and contributes to hepatic glucose production. HNF-4alpha and Foxo1 can physically interact with each other and represent an important signal transduction pathway that regulates the synthesis of glucose in the liver. Foxo1 and HNF-4alpha interact with their own binding sites in the phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) promoters, and this binding is required for their effects on those promoters. However, the effect of physical activity on the HNF-4alpha/Foxo1 pathway is currently unknown. Here, we investigate the protein levels of HNF-4alpha and the HNF-4alpha/Foxo1 pathway in the liver of leptin-deficient (ob/ob) and diet-induced obese Swiss (DIO) mice after acute exercise. The ob/ob and DIO mice swam for four 30 min periods, with 5 min rest intervals for a total swimming time of 2h. Eight hours after the acute exercise protocol, the mice were submitted to an insulin tolerance test (ITT) and determination of biochemical and molecular parameters. Acute exercise improved insulin signalling, increasing insulin-stimulated Akt and Foxo1 phosphorylation and decreasing HNF-4alpha protein levels in the liver of DIO and ob/ob mice under fasting conditions. These phenomena were accompanied by a reduction in the expression of gluconeogenesis genes, such as PEPCK and G6Pase. Importantly, the PI3K inhibitor LY292004 reversed the acute effect of exercise on fasting hyperglycaemia, confirming the involvement of the PI3K pathway. The present study shows that exercise acutely improves the action of insulin in the liver of animal models of obesity and diabetes, resulting in increased phosphorylation and nuclear exclusion of Foxo1, and a reduction in the Foxo1/HNF-4alpha pathway. Since nuclear localization and the association of these proteins is involved in the activation of PEPCK and G6Pase, we believe that the regulation of Foxo1 and HNF-4alpha activities are important mechanisms involved in exercise-induced improvement of glucose homeostasis in insulin resistant states.
De Souza
Cláudio T
CT
Exercise Biochemistry and Physiology Laboratory, Postgraduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina - Criciăúma, SC, Brazil. ctsouza@unesc.net
Frederico
Marisa J S
MJ
da Luz
Gabrielle
G
Cintra
Dennys E
DE
Ropelle
Eduardo R
ER
Pauli
José R
JR
Velloso
Lício A
LA
D021581:Active Transport, Cell Nucleus; D000818:Animals; D003920:Diabetes Mellitus / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D004195:Disease Models, Animal; D015536:Down-Regulation; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000235:genetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D051379:Mice; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D005082:Physical Exertion; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D013550:Swimming
D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D005947:Glucose; D005952:Glucose-6-Phosphatase; D006003:Glycogen; D051557:Hepatocyte Nuclear Factor 4; D007328:Insulin; D019869:Phosphatidylinositol 3-Kinases; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; C467200:Foxo1 protein, mouse; C496593:Hnf4a protein, mouse