This work has been retracted.
Suppression of the mTORC1/STAT3/Notch1 pathway by activated AMPK prevents hepatic insulin resistance induced by excess amino acids
Year: 2013
Type: article
Abstract: Nutrient overload is associated with the development of obesity, insulin resistance, and type 2 diabetes. However, the underlying mechanisms for developing insulin resistance in the presence of excess nutrients are incompletely understood. We investigated whether activation of AMP-activated protein kinase (AMPK) prevents the hepatic insulin resistance that is induced by the consumption of a high-protein diet (HPD) and the presence of excess amino acids. Exposure of HepG2 cells to excess amino acids reduced AMPK phosphorylation, upregulated Notch1 expression, and impaired the insulin-stimulated phosphorylation of Akt Ser(473) and insulin receptor substrate-1 (IRS-1) Tyr(612). Inhibition of Notch1 prevented amino acid-induced insulin resistance, which was accompanied by reduced expression of Rbp-Jk, hairy and enhancer of split-1, and forkhead box O1. Mechanistically, mTORC1 signaling was activated by excess amino acids, which then positively regulated Notch1 expression through the activation of the signal transducer and activator of transcription 3 (STAT3). Activation of AMPK by metformin inhibited mTORC1-STAT3 signaling, thereby preventing excess amino acid-impaired insulin signaling. Finally, HPD feeding suppressed AMPK activity, activated mTORC1/STAT3/Notch1 signaling, and induced insulin resistance. Chronic administration of either metformin or rapamycin inhibited the HPD-activated mTORC1/STAT3/Notch1 signaling pathway and prevented hepatic insulin resistance. We conclude that the upregulation of Notch1 expression by hyperactive mTORC1 signaling is an essential event in the development of hepatic insulin resistance in the presence of excess amino acids. Activation of AMPK prevents amino acid-induced insulin resistance through the suppression of the mTORC1/STAT3/Notch1 signaling pathway.
Institution: University of Oklahoma Health Sciences Center
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Awards: SIRT1, Vascular Aging and an Aortic Aneurysm, Prevention of High Fat Diet-Induced Vascular Injury, Mentoring Diabetes Research in Oklahoma, Autophagy and diabetic vascular diseases, Oxidant stress and diabetic endothelial dysfunction, AMP-activated protein kinase in diabetes, Controlling atherosclerotic plaque stability, Inflammasome and unstable atherosclerotic plaques, Angiotensin-II, GTPCH1 and 26S Protesomes
OpenAlex ID: W2000844923