title: Leucine supplementation increases SIRT1 expression and prevents mitochondrial dysfunction and metabolic disorders in high-fat diet-induced obese mice.
abstract: Leucine supplementation has been shown to prevent high-fat diet (HFD)-induced obesity, hyperglycemia, and dyslipidemia in animal models, but the underlying mechanisms are not fully understood. Recent studies suggest that activation of Sirtuin 1 (SIRT1) is an important mechanism to maintain energy and metabolic homeostasis. We therefore examined the involvement of SIRT1 in leucine supplementation-prevented obesity and insulin resistance. To accomplish this goal, male C57BL/6J mice were fed normal diet or HFD, supplemented with or without leucine. After 2 mo of treatment, alterations in SIRT1 expression, insulin signaling, and energy metabolism were analyzed. Eight weeks of HFD induced obesity, fatty liver, mitochondrial dysfunction, hyperglycemia, and insulin resistance in mice. Addition of leucine to HFD correlated with increased expression of SIRT1 and NAMPT (nicotinamide phosphoribosyltransferase) as well as higher intracellular NAD(+) levels, which decreased acetylation of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α) and forkhead box O1 (FoxO1). The deacetylation of PGC1α may contribute to upregulation of genes controlling mitochondrial biogenesis and fatty acid oxidation, thereby improving mitochondrial function and preventing HFD-induced obesity in mice. Moreover, decreased acetylation of FoxO1 was accompanied by decreased expression of pseudokinase tribble 3 (TRB3) and reduced the association between TRB3 and Akt, which enhanced insulin sensitivity and improved glucose metabolism. Finally, transfection of dominant negative AMPK prevented activation of SIRT1 signaling in HFD-Leu mice. These data suggest that increased expression of SIRT1 after leucine supplementation may lead to reduced acetylation of PGC1α and FoxO1, which is associated with attenuation of HFD-induced mitochondrial dysfunction, insulin resistance, and obesity.
authors.affiliation: Section of Molecular Medicine, Dept. of Medicine, Univ. of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Hongliang
authors.initials: H
authors.lastname: Li
authors.forename: Mingjiang
authors.initials: M
authors.lastname: Xu
authors.forename: Jiyeon
authors.initials: J
authors.lastname: Lee
authors.forename: Chaoyong
authors.initials: C
authors.lastname: He
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Xie
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D019587:Dietary Supplements; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005786:Gene Expression Regulation; D015309:Glucose Clamp Technique; D007333:Insulin Resistance / Q000502:physiology*; D007930:Leucine / Q000008:administration & dosage* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D063269:Mitochondrial Turnover; D054409:Nicotinamide Phosphoribosyltransferase / Q000235:genetics / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000517:prevention & control; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012313:RNA / Q000737:chemistry / Q000235:genetics; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
chemical_list: D018797:Cell Cycle Proteins; D016207:Cytokines; D004272:DNA, Mitochondrial; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C467200:Foxo1 protein, mouse; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; C474830:TRB3 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D012313:RNA; D054409:Nicotinamide Phosphoribosyltransferase; C495867:nicotinamide phosphoribosyltransferase, mouse; D055372:AMP-Activated Protein Kinases; D056564:Sirtuin 1; D007930:Leucine