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Overexpression of c ‐myc in the liver prevents obesity and insulin resistance
Author(s) -
Riu Efren,
Ferre Tura,
Hidalgo Antonio,
Mas Alex,
Franckhauser Sylvie,
Otaegui Pedro,
Bosch Fatima
Publication year - 2003
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.02-1163fje
Subject(s) - endocrinology , medicine , insulin resistance , glucokinase , biology , gluconeogenesis , carbohydrate metabolism , insulin receptor , glycogen , glycogen synthase , insulin , steatosis , lipid metabolism , metabolism
Alterations in hepatic glucose metabolism play a key role in the development of the hyperglycemia observed in type 2 diabetes. Because the transcription factor c‐Myc induces hepatic glucose uptake and utilization and blocks gluconeogenesis, we examined whether hepatic overexpression of c ‐myc counteracts the insulin resistance induced by a high‐fat diet. After 3 months on this diet, control mice became obese, hyperglycemic, and hyperinsulinemic, indicating that they had developed insulin resistance. In contrast, transgenic mice remained lean and showed improved glucose disposal and normal levels of blood glucose and insulin, indicating that they had developed neither obesity nor insulin resistance. These findings were concomitant with normalization of hepatic glucokinase and pyruvate kinase gene expression and enzyme activity, which led to normalization of intrahepatic glucose‐6‐phosphate and glycogen content. In the liver of control mice fed a high‐fat diet, the expression of genes encoding proteins that control energy metabolism, such as sterol receptor element binding protein 1‐c, peroxisome proliferator activated receptor α, and uncoupling protein‐2, was altered. In contrast, in the liver of transgenic mice fed a high‐fat diet, the expression of these genes was normal. These results suggest that c ‐myc overexpression counteracted the obesity and insulin resistance induced by a high‐fat diet by modulating the expression of genes that regulate hepatic metabolism.