Author
Chikage Mataki
Other affiliations: French Institute of Health and Medical Research
Bio: Chikage Mataki is an academic researcher from École Polytechnique Fédérale de Lausanne. The author has contributed to research in topics: Insulin resistance & Adipose tissue. The author has an hindex of 16, co-authored 17 publications receiving 5619 citations. Previous affiliations of Chikage Mataki include French Institute of Health and Medical Research.
Papers
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TL;DR: It is shown that the administration of BAs to mice increases energy expenditure in brown adipose tissue, preventing obesity and resistance to insulin, and indicates that BAs might be able to function beyond the control of BA homeostasis as general metabolic integrators.
Abstract: While bile acids (BAs) have long been known to be essential in dietary lipid absorption and cholesterol catabolism, in recent years an important role for BAs as signalling molecules has emerged. BAs activate mitogen-activated protein kinase pathways, are ligands for the G-protein-coupled receptor (GPCR) TGR5 and activate nuclear hormone receptors such as farnesoid X receptor alpha (FXR-alpha; NR1H4). FXR-alpha regulates the enterohepatic recycling and biosynthesis of BAs by controlling the expression of genes such as the short heterodimer partner (SHP; NR0B2) that inhibits the activity of other nuclear receptors. The FXR-alpha-mediated SHP induction also underlies the downregulation of the hepatic fatty acid and triglyceride biosynthesis and very-low-density lipoprotein production mediated by sterol-regulatory-element-binding protein 1c. This indicates that BAs might be able to function beyond the control of BA homeostasis as general metabolic integrators. Here we show that the administration of BAs to mice increases energy expenditure in brown adipose tissue, preventing obesity and resistance to insulin. This novel metabolic effect of BAs is critically dependent on induction of the cyclic-AMP-dependent thyroid hormone activating enzyme type 2 iodothyronine deiodinase (D2) because it is lost in D2-/- mice. Treatment of brown adipocytes and human skeletal myocytes with BA increases D2 activity and oxygen consumption. These effects are independent of FXR-alpha, and instead are mediated by increased cAMP production that stems from the binding of BAs with the G-protein-coupled receptor TGR5. In both rodents and humans, the most thermogenically important tissues are specifically targeted by this mechanism because they coexpress D2 and TGR5. The BA-TGR5-cAMP-D2 signalling pathway is therefore a crucial mechanism for fine-tuning energy homeostasis that can be targeted to improve metabolic control.
1,852 citations
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TL;DR: It is shown here that TGR5 signaling induces intestinal glucagon-like peptide-1 (GLP-1) release, leading to improved liver and pancreatic function and enhanced glucose tolerance in obese mice, and suggested that pharmacological targeting of T GR5 may constitute a promising incretin-based strategy for the treatment of diabesity and associated metabolic disorders.
1,412 citations
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TL;DR: It is concluded that AMPK acts as the primordial trigger for fasting- and exercise-induced adaptations in skeletal muscle and that activation of SIRT1 and its downstream signaling pathways are improperly triggered in AMPK-deficient states.
769 citations
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TL;DR: The metabolic phenotype of mice treated with SRT1720, a specific and potent synthetic activator of SIRT1 that is devoid of direct action on AMPK that robustly enhances endurance running performance and strongly protects from diet-induced obesity and insulin resistance by enhancing oxidative metabolism in skeletal muscle, liver, and brown adipose tissue is reported.
702 citations
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TL;DR: This paper evaluated the metabolic impact of farnesoid X receptor activation by administering a synthetic FXR agonist (GW4064) to mice in which obesity was induced by a high fat diet.
229 citations
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TL;DR: Nine tentative hallmarks that represent common denominators of aging in different organisms are enumerated, with special emphasis on mammalian aging, to identify pharmaceutical targets to improve human health during aging, with minimal side effects.
9,980 citations
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TL;DR: The role of adipokines in inflammatory responses is focused on and their potential as regulators of metabolic function is discussed.
Abstract: The worldwide epidemic of obesity has brought considerable attention to research aimed at understanding the biology of adipocytes (fat cells) and the events occurring in adipose tissue (fat) and in the bodies of obese individuals. Accumulating evidence indicates that obesity causes chronic low-grade inflammation and that this contributes to systemic metabolic dysfunction that is associated with obesity-linked disorders. Adipose tissue functions as a key endocrine organ by releasing multiple bioactive substances, known as adipose-derived secreted factors or adipokines, that have pro-inflammatory or anti-inflammatory activities. Dysregulated production or secretion of these adipokines owing to adipose tissue dysfunction can contribute to the pathogenesis of obesity-linked complications. In this Review, we focus on the role of adipokines in inflammatory responses and discuss their potential as regulators of metabolic function.
3,528 citations
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TL;DR: AMP-activated protein kinase conserves ATP levels through the regulation of processes other than metabolism, such as the cell cycle and neuronal membrane excitability.
Abstract: AMP-activated protein kinase (AMPK) is a crucial cellular energy sensor. Once activated by falling energy status, it promotes ATP production by increasing the activity or expression of proteins involved in catabolism while conserving ATP by switching off biosynthetic pathways. AMPK also regulates metabolic energy balance at the whole-body level. For example, it mediates the effects of agents acting on the hypothalamus that promote feeding and entrains circadian rhythms of metabolism and feeding behaviour. Finally, recent studies reveal that AMPK conserves ATP levels through the regulation of processes other than metabolism, such as the cell cycle and neuronal membrane excitability.
3,465 citations
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TL;DR: Through increased knowledge of the mechanisms involved in the interactions between the microbiota and its host, the world will be in a better position to develop treatments for metabolic disease.
Abstract: The link between the microbes in the human gut and the development of obesity, cardiovascular disease and metabolic syndromes, such as type 2 diabetes, is becoming clearer. However, because of the complexity of the microbial community, the functional connections are less well understood. Studies in both mice and humans are helping to show what effect the gut microbiota has on host metabolism by improving energy yield from food and modulating dietary or the host-derived compounds that alter host metabolic pathways. Through increased knowledge of the mechanisms involved in the interactions between the microbiota and its host, we will be in a better position to develop treatments for metabolic disease.
3,436 citations
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TL;DR: It is demonstrated that AMPK controls the expression of genes involved in energy metabolism in mouse skeletal muscle by acting in coordination with another metabolic sensor, the NAD+-dependent type III deacetylase SIRT1.
Abstract: AMP-activated protein kinase (AMPK) is a metabolic fuel gauge conserved along the evolutionary scale in eukaryotes that senses changes in the intracellular AMP/ATP ratio. Recent evidence indicated an important role for AMPK in the therapeutic benefits of metformin, thiazolidinediones and exercise, which form the cornerstones of the clinical management of type 2 diabetes and associated metabolic disorders. In general, activation of AMPK acts to maintain cellular energy stores, switching on catabolic pathways that produce ATP, mostly by enhancing oxidative metabolism and mitochondrial biogenesis, while switching off anabolic pathways that consume ATP. This regulation can take place acutely, through the regulation of fast post-translational events, but also by transcriptionally reprogramming the cell to meet energetic needs. Here we demonstrate that AMPK controls the expression of genes involved in energy metabolism in mouse skeletal muscle by acting in coordination with another metabolic sensor, the NAD+-dependent type III deacetylase SIRT1. AMPK enhances SIRT1 activity by increasing cellular NAD+ levels, resulting in the deacetylation and modulation of the activity of downstream SIRT1 targets that include the peroxisome proliferator-activated receptor-gamma coactivator 1alpha and the forkhead box O1 (FOXO1) and O3 (FOXO3a) transcription factors. The AMPK-induced SIRT1-mediated deacetylation of these targets explains many of the convergent biological effects of AMPK and SIRT1 on energy metabolism.
2,649 citations