Metabolism
Abstract
BACKGROUND. Responses of the metabolome to acute aerobic exercise may predict VO2max and longer-term outcomes, including the development of diabetes and its complications. METHODS. Serum samples were collected from overweight trained (OWT) and normal weight trained (NWT) runners prior to and immediately after a supervised 90-minute treadmill run at 60% VO2max (NWT = 14, OWT = 11) in a cross-sectional study. We applied a liquid chromatography high resolution-mass spectrometry based untargeted metabolomics platform to evaluate the effect of acute aerobic exercise on the serum metabolome. RESULTS. NWT and OWT metabolic profiles shared increased circulating acylcarnitines and free fatty acids (FFAs) with exercise while intermediates of adenine metabolism, inosine and hypoxanthine, were strongly correlated with body fat percentage and VO2max. Untargeted metabolomics-guided follow-up quantitative lipidomic analysis revealed that baseline levels of fatty acid esters of hydroxy fatty acids (FAHFAs) were generally diminished in the OWT group. FAHFAs negatively correlated with visceral fat mass and HOMA-IR. Strikingly, a 4-fold decrease in FAHFAs was provoked by acute aerobic running in NWT, an effect that negatively correlated with circulating IL-6, neither of which was observed in the OWT group. Machine learning models based on a pre-exercise metabolite profile that included FAHFAs, FFAs, and adenine intermediates predicted VO2max. CONCLUSION. These findings in overweight human participants and healthy controls indicate that exercise-provoked changes in FAHFAs distinguish normal weight from overweight individuals and could predict VO2max. These results support the notion that FAHFAs could modulate the inflammatory response, fuel utilization, and insulin resistance. TRIAL REGISTRATION. ClinicalTrials.gov NCT02150889. FUNDING. NIH DK091538, AG069781, DK098203, TR000114, UL1TR002494.
Authors
Alisa B. Nelson, Lisa S. Chow, David B. Stagg, Jacob R. Gillingham, Michael D. Evans, Meixia Pan, Curtis C. Hughey, Chad L. Myers, Xianlin Han, Peter A. Crawford, Patrycja Puchalska
Abstract
BACKGROUND. NAFLD affects 25-30% of the US and European populations and is associated with insulin resistance (IR), T2D, increased cardiovascular risk and is defined by hepatic triglyceride content (HTG) > 5.56%. However, it is unknown whether HTG content less than 5.56% is associated with cardiometabolic risk factors and whether there are ethnic [Asian Indian (AI) vs. non-Asian Indian (non-AI)] and/or gender differences in these parameters in lean individuals. METHODS. We prospectively recruited 2,331 individuals and measured HTG, using 1H MRS, and plasma concentrations of triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol, and uric acid. Insulin sensitivity was assessed using HOMA-IR and the Matsuda Insulin Sensitivity Index (ISI). RESULTS. The 95th percentile for HTG in lean non-AI individuals was 1.85%. Plasma insulin, triglycerides, total cholesterol, LDL cholesterol and uric acid concentrations were increased and HDL decreased in individuals with HTG content > 1.85% and ≤ 5.56% compared to those individuals with HTG content ≤ 1.85% and was associated with increased IR. Mean HTG was lower in lean non-AI women compared to lean non-AI men, whereas lean AI men and women had a 40-100% increase in HTG when compared to non-AI men and women which was associated with increased cardiometabolic risk factors. CONCLUSIONS. We found that the 95th percentile of HTG in lean non-AI individuals was 1.85% and that HTG concentrations above this threshold were associated with IR and cardiovascular risk factors. Premenopausal women are protected from these changes whereas young lean AI men and women manifest increased HTG content and associated cardiometabolic risk factors. FUNDING. Supported by grants from the United States Department of Health and Human Resources (NIH/NIDDK): R01 DK113984, P30 DK45735, U24 DK59635 and UL1 RR024139 and the Novo Nordisk Foundation (NNF18CC0034900).
Authors
Kitt Falk Petersen, Sylvie Dufour, Fangyong Li, Douglas L. Rothman, Gerald I. Shulman
Abstract
Diabetic nephropathy (DN) arises from systemic and local changes in glucose metabolism and hemodynamics. We have reported that many glycolytic and mitochondrial enzymes, such as pyruvate kinase M2 (PKM2), were elevated in renal glomeruli of DN-protected type 1 and type 2 diabetic patients. Here, mice with PKM2-specific overexpression in podocytes (PPKM2Tg) were generated to uncover its renal protective function as potential therapeutic target, which prevented elevated albumin-creatinine ratio (ACR), mesangial expansion, basement membrane thickness and podocyte foot process effacement after 7-months of STZ-induced diabetes. Further, diabetes-induced impairment of glycolytic rate and mitochondrial function were normalized in diabetic PPKM2Tg glomeruli, in concordance with elevated Ppargc1a and Vegf expressions. Restored VEGF expression improved glomerular maximal mitochondrial function in diabetic PPKM2Tg and WT mice. Elevated VEGF levels were observed in the glomeruli of DN-protected patients with chronic type 1 diabetes, and clinically correlated with estimated GFR, but not glycemic control. Mechanistically, the preservations of mitochondrial function and VEGF expression were dependent on tetrameric structure and enzymatic activities of PKM2 in podocyte. These findings demonstrated that PKM2 structure and enzymatic activation in podocytes can preserve entire glomerular mitochondrial function against toxicity of hyperglycemia via paracrine factors such as VEGF and prevent DN progression.
Authors
Jialin Fu, Takanori Shinjo, Qian Li, Ronald St-Louis, Kyoungmin Park, Marc G. Yu, Hisashi Yokomizo, Fabricio Simao, Qian Huang, I-Hsien Wu, George L. King
Abstract
Metabolomics has been used to explore the molecular mechanism and screen biomarkers. However, the critical metabolic signatures associated with benzene-induced hematotoxicity remain elusive. Here, we performed a plasma metabolomics study in 86 benzene-exposed workers and 76 healthy controls, followed by a validation analysis in mice, to investigate the dynamical change of the metabolic profile. We found that 8 fatty acids were significantly altered in both benzene-exposed worker and benzene-exposed animal models. These metabolites were significantly associated with S-phenylmercapturic acid and WBC, and they mediated the benzene-induced WBC decline. Furthermore, in vivo results confirm that fatty acid levels were dynamically altered, characterized by a decrease at 15 days and then sharp increases at 30 and 45 days. Following these identified fatty acids, the potential metabolic pathways were investigated. Fatty acids, as precursors for fatty acid oxidation, may disturb the balance of fatty acid biosynthesis and degradation. Our results reveal that fatty acid metabolism was strongly reprogrammed after benzene exposure. This abnormal change of fatty acids might be the key metabolic signature associated with benzene-induced hematotoxicity.
Authors
Xiaoli Guo, Lei Zhang, Jingyu Wang, Wei Zhang, Jing Ren, Yujiao Chen, Yanlin Zhang, Ai Gao
Abstract
Impaired glucose metabolism is observed in obesity and type 2 diabetes. Glucose controls gene expression through the transcription factor ChREBP in liver and adipose tissues. Mlxipl encodes two isoforms, ChREBPα, the full-length form which translocation into the nucleus is under the control of glucose and, ChREBPβ, a constitutively nuclear shorter form. ChREBPβ gene expression in white adipose tissue is strongly associated with insulin sensitivity. Here, we investigated the consequences of ChREBPβ deficiency on insulin action and energy balance. ChREBPβ-deficient male and female C57BL6/J and FVB/N mice were produced using CRISPR-Cas9-mediated gene editing. Unlike global ChREBP deficiency, lack of ChREBPβ showed modest effects on gene expression in adipose tissues and liver, with variations seen chiefly in brown adipose tissue. In mice fed chow and high fat diets, lack of ChREBPβ had moderate effects on body composition and insulin sensitivity. ChREBPβ deficiency did not prevent the whitening of brown adipose tissue reported in total ChREBP knock out mice at thermoneutrality. These findings reveal that ChREBPβ is dispensable for metabolic adaptations to nutritional and thermic challenges.
Authors
Emeline Recazens, Geneviève Tavernier, Jérémy Dufau, Camille Bergoglio, Fadila Benhamed, Stéphanie Cassant-Sourdy, Marie-Adeline Marques, Sylvie Caspar-Bauguil, Alice Brion, Laurent Monbrun, Renaud Dentin, Clara Ferrier, Mélanie Leroux, Pierre-Damien Denechaud, Cedric Moro, Jean-Paul Concordet, Catherine Postic, Etienne Mouisel, Dominique Langin
Abstract
Mitophagy and mitochondrial integrated stress response (ISR) are two primary protective mechanisms to maintain functional mitochondria. Whether these two processes are coordinately regulated remains unclear. Here we show that mitochondrial fission 1 protein (Fis1), which is required for completion of mitophagy, serves as a signaling hub linking mitophagy and ISR. In mouse hepatocytes, high fat diet (HFD) feeding induces unresolved oxidative stress, defective mitophagy and enhanced type I interferon (IFN-I) response implicated in promoting metabolic inflammation. Adenoviral-mediated acute hepatic Fis1 over-expression is sufficient to reduce oxidative damage and improve glucose homeostasis in HFD fed mice. RNA-seq analysis reveals that Fis1 triggers a retrograde mitochondria-to-nucleus communication upregulating ISR genes encoding anti-oxidant defense, redox homeostasis and proteostasis pathways. Fis1-mediated ISR also suppresses expression of IFN-I stimulated genes through Atf5, which inhibits the transactivation activity of Irf3 known to control IFN-I production. Metabolite analysis demonstrates that Fis1 activation leads to accumulation of fumarate, a TCA cycle intermediate capable of increasing Atf5 activity. Consequently, hepatic Atf5 over-expression or monomethyl fumarate (MMF) treatment improves glucose homeostasis in HFD fed mice. Collectively, these results support the potential use of small molecules targeting the Fis1-Atf5 axis, such as MMF, to treat metabolic diseases.
Authors
Yae-Huei Liou, Jean Personnaz, David Jacobi, Nelson H. Knudsen, Mayer M. Chalom, Kyle A. Starost, Israel C. Nnah, Chih-Hao Lee
Abstract
Increased adipose tissue macrophages (ATM) correlate with metabolic dysfunction in humans and are causal in development of insulin resistance in mice. Recent bulk and single cell transcriptomics studies reveal a wide spectrum of gene expression signatures possible for macrophages that depends on context, but the signatures of human ATM subtypes are not well defined in obesity and diabetes. We profiled three prominent ATM subtypes from human adipose tissue in obesity and determined their relationship to type 2 diabetes. Visceral (VAT) and subcutaneous (SAT) adipose tissue samples were collected from diabetic and non-diabetic obese subjects to evaluate cellular content and gene expression. VAT CD206+CD11c− ATMs were increased in diabetic subjects, scavenger receptor-rich with low intracellular lipids, secreted proinflammatory cytokines, and diverged significantly from two CD11c+ ATM subtypes, which were lipid-laden, lipid antigen presenting, and overlapped with monocyte signatures. Furthermore, diabetic VAT was enriched for CD206+CD11c− ATM and inflammatory signatures, scavenger receptors, and MHC II antigen presentation genes. VAT immunostaining found CD206+CD11c− ATMs concentrated in vascularized lymphoid clusters adjacent to CD206−CD11c+ ATMs, while CD206+CD11c+ were distributed between adipocytes. Our results suggest ATM subtype-specific profiles that uniquely contribute to the phenotypic variation in obesity.
Authors
Lindsey A. Muir, Kae Won Cho, Lynn M. Geletka, Nicki A. Baker, Carmen G. Flesher, Anne P. Ehlers, Niko Kaciroti, Stephen Lindsly, Scott Ronquist, Indika Rajapakse, Robert W. O’Rourke, Carey N. Lumeng
Abstract
Colorectal cancer (CRC) very severely threatens human health and lifespan. Effective therapeutic strategy has not been established because of without clearly knowing its pathogenesis. Here we report that ceramide and SOAT1 have the roles on both spontaneous and chemical-induced intestine cancers. It was first found by us that miR-148a deficiency dramatically increased mouse gut dysbiosis through upregulating Cers5 expression, which promoted ceramide synthesis afterward. The newly generated ceramide further promoted both AOM/DSS-induced and ApcMin/+ spontaneous intestine tumorigenesis via increasing mouse gut dysbiosis. Meanwhile, increased level of ceramide correlated with the significant enhancements on both β-catenin activity and colorectal tumorigenesis in a fashion of TLR4-dependent. Next, it was found that a direct binding of β-catenin to SOAT1 promoter to activate transcriptional expression of SOAT1, which further induced cholesterol esterification and colorectal tumorigenesis. In human patients of CRC, the same CERS5-TLR4-β-catenin-SOAT1 axis was also found with dysregulation. Finally, the SOAT1 inhibitor (Avasimibe) showed the significant levels of therapeutic effects on both AOM/DSS-induced and ApcMin/+ spontaneous intestine cancer. Our study clarified that ceramide promoted CRC development through increasing gut dysbiosis, further resulting in the increase of cholesterol esterification in a special way of SOAT1-dependent. The treatment through Avasimibe to specifically decrease cholesterol esterification could be considered as a clinical strategy for effective CRC therapy in future study.
Authors
Yahui Zhu, Li Gu, Xi Lin, Jinmiao Zhang, Yi Tang, Xinyi Zhou, Bingjun Lu, Xingrong Lin, Cheng Liu, Edward V. Prochownik, Youjun Li
Abstract
The biosynthetic routes leading to de novo Nicotinamine Adenine Dinucleotide (NAD+) production are involved in acute kidney injury (AKI) with a critical role for Quinolinate Phosphoribosyl Transferase (QPRT), a bottleneck enzyme of de novo NAD+ biosynthesis. However, the molecular mechanisms determining reduced QPRT in AKI, and the role of impaired NAD+ biosynthesis in the progression to chronic kidney disease (CKD) are unknown. We demonstrate that a high urinary quinolinate to tryptophan ratio, an indirect indicator of impaired QPRT activity and reduced de novo NAD+ biosynthesis in the kidney, is a clinically applicable early marker of AKI after cardiopulmonary bypass, and is predictive of progression to chronic kidney disease (CKD) in kidney transplant recipients. We also provide evidence that the Endoplasmic Reticulum (ER) stress response impairs de novo NAD+ biosynthesis by repressing QPRT transcription. In conclusion, NAD+ biosynthesis impairment is an early event in AKI embedded with the ER stress response, and persistent reduction of QPRT expression is associated with AKI to CKD progression. This defines non-invasive metabolic biomarkers of kidney injury with prognostic and therapeutic implications.
Authors
Yohan Bignon, Anna Rinaldi, Zahia Nadour, Virginie Poindessous, Ivan Nemazanyy, Olivia Lenoir, Baptiste Fohlen, Pierre Weill-Raynal, Alexandre Hertig, Alexandre Karras, Pierre Galichon, Maarten Naesens, Dany Anglicheau, Pietro E. Cippà, Nicolas Pallet
Abstract
Glucagon, a hormone released from pancreatic α-cells, plays a key role in maintaining euglycemia. New insights into the signaling pathways that control glucagon secretion may stimulate the development of novel therapeutic agents. In this study, we investigated the potential regulation of α-cell function by G proteins of the Gq family. The use of a chemogenetic strategy allowed us to selectively activate Gq signaling in mouse α-cells in vitro and in vivo. Acute stimulation of α-cell Gq signaling led to elevated plasma glucagon levels, accompanied by increased insulin release and improved glucose tolerance. Moreover, chronic activation of this pathway greatly improved glucose tolerance in obese mice. We also identified an endogenous Gq-coupled receptor (vasopressin 1b receptor; V1bR) that is enriched in mouse and human α-cells. Agonist-induced activation of the V1bR strongly stimulated glucagon release in a Gq-dependent fashion. In vivo studies indicated that V1bR-mediated glucagon release plays a key role in the counter-regulatory hyperglucagonemia under hypoglycemic and glucopenic conditions. These data indicate that α-cell Gq signaling represents an important regulator of glucagon secretion, resulting in multiple beneficial metabolic effects. Thus, drugs that target α-cell enriched Gq-coupled receptors may prove useful to restore euglycemia in various pathophysiological conditions.
Authors
Liu Liu, Diptadip Dattaroy, Katherine F. Simpson, Luiz F. Barella, Yinghong Cui, Yan Xiong, Jian Jin, Gabriele M. König, Evi Kostenis, Jefferey C. Roman, Klaus H. Kaestner, Nicolai M. Doliba, Jürgen Wess
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