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Ruocco C, Malavazos AE, Ragni M, Carruba MO, Valerio A, Iacobellis G, Nisoli E. Amino acids contribute to adaptive thermogenesis. New insights into the mechanisms of action of recent drugs for metabolic disorders are emerging. Pharmacol Res 2023; 195:106892. [PMID: 37619907 DOI: 10.1016/j.phrs.2023.106892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/28/2023] [Accepted: 08/17/2023] [Indexed: 08/26/2023]
Abstract
Adaptive thermogenesis is the heat production by muscle contractions (shivering thermogenesis) or brown adipose tissue (BAT) and beige fat (non-shivering thermogenesis) in response to external stimuli, including cold exposure. BAT and beige fat communicate with peripheral organs and the brain through a variegate secretory and absorption processes - controlling adipokines, microRNAs, extracellular vesicles, and metabolites - and have received much attention as potential therapeutic targets for managing obesity-related disorders. The sympathetic nervous system and norepinephrine-releasing adipose tissue macrophages (ATM) activate uncoupling protein 1 (UCP1), expressed explicitly in brown and beige adipocytes, dissolving the electrochemical gradient and uncoupling tricarboxylic acid cycle and the electron transport chain from ATP production. Mounting evidence has attracted attention to the multiple effects of dietary and endogenously synthesised amino acids in BAT thermogenesis and metabolic phenotype in animals and humans. However, the mechanisms implicated in these processes have yet to be conclusively characterized. In the present review article, we aim to define the principal investigation areas in this context, including intestinal microbiota constitution, adipose autophagy modulation, and secretome and metabolic fluxes control, which lead to increased brown/beige thermogenesis. Finally, also based on our recent epicardial adipose tissue results, we summarise the evidence supporting the notion that the new dual and triple agonists of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon (GCG) receptor - with never before seen weight loss and insulin-sensitizing efficacy - promote thermogenic-like amino acid profiles in BAT with robust heat production and likely trigger sympathetic activation and adaptive thermogenesis by controlling amino acid metabolism and ATM expansion in BAT and beige fat.
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Affiliation(s)
- Chiara Ruocco
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy
| | - Alexis Elias Malavazos
- Endocrinology Unit, Clinical Nutrition and Cardiovascular Prevention Service, IRCCS Policlinico San Donato, Piazza Edmondo Malan, 2, San Donato Milanese, 20097 Milan, Italy; Department of Biomedical, Surgical and Dental Sciences, University of Milan, via della Commenda, 10, 20122 Milan, Italy
| | - Maurizio Ragni
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy
| | - Michele O Carruba
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy
| | - Alessandra Valerio
- Department of Molecular and Translational Medicine, University of Brescia, viale Europa, 11, 25123 Brescia, Italy
| | - Gianluca Iacobellis
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami, 1400 NW 12th Ave, Miami, FL, USA
| | - Enzo Nisoli
- Center for Study and Research on Obesity, Department of Biomedical Technology and Translational Medicine, University of Milan, via Vanvitelli, 32, 20129 Milan, Italy.
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Mestres-Arenas A, Cairó M, Peyrou M, Villarroya F. Blood Sampling for Arteriovenous Difference Measurements Across Interscapular Brown Adipose Tissue in Rat. Methods Mol Biol 2022; 2448:273-282. [PMID: 35167103 DOI: 10.1007/978-1-0716-2087-8_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A classic physiological approach to assess the specific uptake or release of circulating factors in organs and tissues is to measure concentration differences between venous and arterial blood. For interscapular brown adipose tissue (iBAT), the anatomic distribution of its vascularization, which drains most of the blood into Sulzer's vein, allows for local measurement of arteriovenous differences. The use of this procedure to monitor oxygen concentration changes was fundamental for the recognition of BAT as the main site of adaptive non-shivering thermogenesis. More recently, this technique has regained importance as a means to identify BAT-secreted regulatory molecules, such as fibroblast growth factor-21 and the chemokine CXCL14. In this chapter, we provide a detailed description of an optimized and feasible protocol to determine arteriovenous differences across iBAT. We include tips and practical advice for using this powerful tool to study BAT metabolism and secretory activity in rats as an experimental model.
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Affiliation(s)
- Alberto Mestres-Arenas
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Institut de Recerca Sant Joan de Déu, Esplugues, Catalonia, Spain
| | - Montserrat Cairó
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Institut de Recerca Sant Joan de Déu, Esplugues, Catalonia, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Madrid, Spain
| | - Marion Peyrou
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Institut de Recerca Sant Joan de Déu, Esplugues, Catalonia, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Madrid, Spain
| | - Francesc Villarroya
- Departament de Bioquímica i Biomedicina Molecular, Universitat de Barcelona, Barcelona, Catalonia, Spain.
- Institut de Recerca Sant Joan de Déu, Esplugues, Catalonia, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición, Madrid, Spain.
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Suppression of Brown Adipocyte Autophagy Improves Energy Metabolism by Regulating Mitochondrial Turnover. Int J Mol Sci 2019; 20:ijms20143520. [PMID: 31323770 PMCID: PMC6678363 DOI: 10.3390/ijms20143520] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 12/18/2022] Open
Abstract
The high abundance of mitochondria and the expression of mitochondrial uncoupling protein 1 (UCP1) confer upon brown adipose tissue (BAT) the unique capacity to convert chemical energy into heat at the expense of ATP synthesis. It was long believed that BAT is present only in infants, and so, it was not considered as a potential therapeutic target for metabolic syndrome; however, the discovery of metabolically active BAT in adult humans has re-stimulated interest in the contributions of BAT metabolic regulation and dysfunction to health and disease. Here we demonstrate that brown adipocyte autophagy plays a critical role in the regulation BAT activity and systemic energy metabolism. Mice deficient in brown adipocyte autophagy due to BAT-specific deletion of Atg7-a gene essential for autophagosome generation-maintained higher mitochondrial content due to suppression of mitochondrial clearance and exhibited improved insulin sensitivity and energy metabolism. Autophagy was upregulated in BAT of older mice compared to younger mice, suggesting its involvement in the age-dependent decline of BAT activity and metabolic rate. These findings suggest that brown adipocyte autophagy plays a crucial role in metabolism and that targeting this pathway may be a potential therapeutic strategy for metabolic syndrome.
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Abstract
Brown and beige adipocytes can catabolize stored energy to generate heat, and this distinct capacity for thermogenesis could be leveraged as a therapy for metabolic diseases like obesity and type 2 diabetes. Thermogenic adipocytes drive heat production through close coordination of substrate supply with the mitochondrial oxidative machinery and effectors that control the rate of substrate oxidation. Together, this apparatus affords these adipocytes with tremendous capacity to drive thermogenesis. The best characterized thermogenic effector is uncoupling protein 1 (UCP1). Importantly, additional mechanisms for activating thermogenesis beyond UCP1 have been identified and characterized to varying extents. Acute regulation of these thermogenic pathways has been an active area of study, and numerous regulatory factors have been uncovered in recent years. Here we will review the evidence for regulators of heat production in thermogenic adipocytes in the context of the thermodynamic and kinetic principles that govern their therapeutic utility.
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Affiliation(s)
- Edward T Chouchani
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
| | - Lawrence Kazak
- Goodman Cancer Research Centre, McGill University, Montreal, QC, Canada; Department of Biochemistry, McGill University, Montreal, QC, Canada.
| | - Bruce M Spiegelman
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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