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Ott RK, Williams IH, Armstrong AR. Improved whole-mount immunofluorescence protocol for consistent and robust labeling of adult Drosophila melanogaster adipose tissue. Biol Open 2024; 13:bio060491. [PMID: 39041865 DOI: 10.1242/bio.060491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 07/11/2024] [Indexed: 07/24/2024] Open
Abstract
Energy storage and endocrine functions of the Drosophila fat body make it an excellent model for elucidating mechanisms that underlie physiological and pathophysiological organismal metabolism. Combined with Drosophila's robust genetic and immunofluorescence microscopy toolkits, studies of Drosophila fat body function are ripe for cell biological analysis. Unlike the larval fat body, which is easily removed as a single, cohesive sheet of tissue, isolating intact adult fat body proves to be more challenging, thus hindering consistent immunofluorescence labeling even within a single piece of adipose tissue. Here, we describe an improved approach to handling Drosophila abdomens that ensures full access of the adult fat body to solutions generally used in immunofluorescence labeling protocols. In addition, we assess the quality of fluorescence reporter expression and antibody immunoreactivity in response to variations in fixative type, fixation incubation time, and detergent used for cellular permeabilization. Overall, we provide several recommendations for steps in a whole-mount staining protocol that results in consistent and robust immunofluorescence labeling of the adult Drosophila fat body.
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Affiliation(s)
- Rachael K Ott
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29072, USA
| | - Isaiah H Williams
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29072, USA
| | - Alissa R Armstrong
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29072, USA
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2
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Chaurasiya V, Nidhina Haridas PA, Olkkonen VM. Adipocyte-endothelial cell interplay in adipose tissue physiology. Biochem Pharmacol 2024; 222:116081. [PMID: 38408682 DOI: 10.1016/j.bcp.2024.116081] [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] [Received: 10/31/2023] [Revised: 02/02/2024] [Accepted: 02/22/2024] [Indexed: 02/28/2024]
Abstract
Adipose tissue (AT) expansion through hyperplasia or hypertrophy requires vascular remodeling that involves angiogenesis. There is quite some evidence that obese white AT (WAT) displays altered vasculature. Some studies suggest that this is associated with hypoxia, which is thought to play a role in inducing inflammatory activation of the excessively expanding WAT. Increasing evidence, based on genetic manipulations or treatments with inhibitory or activator pharmaceuticals, demonstrates that AT angiogenesis is crucial for AT metabolic function, and thereby for whole body metabolism and metabolic health. Despite some contradiction between studies, disturbance of WAT angiogenesis in obesity could be an important factor driving WAT dysfunction and the comorbidities of obesity. Endothelial cells (ECs) contribute to healthy WAT metabolism via transport of fatty acids and other plasma components, secretory signaling molecules, and extracellular vesicles (EVs). This communication is crucial for adipocyte metabolism and underscores the key role that the AT endothelium plays in systemic energy homeostasis and healthy metabolism. Adipocytes communicate towards the neighboring endothelium through several mechanisms. The pro-inflammatory status of hypertrophic adipocytes in obesity is reflected in ECs activation, which promotes chronic inflammation. On the other hand, adiponectin secreted by the adipocytes is important for healthy endothelial function, and adipocytes also secrete other pro- or anti-angiogenic effector molecules and a wealth of EVs - however, their detailed roles in signaling towards the endothelium are yet poorly understood. To conclude, targeting AT angiogenesis and promoting the healthy communication between adipocytes and ECs represent potentially promising strategies to treat obesity and its comorbidities.
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Affiliation(s)
- Vaishali Chaurasiya
- Minerva Foundation Institute for Medical Research, Helsinki, Finland, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
| | - P A Nidhina Haridas
- Minerva Foundation Institute for Medical Research, Helsinki, Finland, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland, and Department of Anatomy, Faculty of Medicine, University of Helsinki, Finland.
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Ramasamy I. Physiological Appetite Regulation and Bariatric Surgery. J Clin Med 2024; 13:1347. [PMID: 38546831 PMCID: PMC10932430 DOI: 10.3390/jcm13051347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 02/22/2024] [Accepted: 02/24/2024] [Indexed: 04/10/2024] Open
Abstract
Obesity remains a common metabolic disorder and a threat to health as it is associated with numerous complications. Lifestyle modifications and caloric restriction can achieve limited weight loss. Bariatric surgery is an effective way of achieving substantial weight loss as well as glycemic control secondary to weight-related type 2 diabetes mellitus. It has been suggested that an anorexigenic gut hormone response following bariatric surgery contributes to weight loss. Understanding the changes in gut hormones and their contribution to weight loss physiology can lead to new therapeutic treatments for weight loss. Two distinct types of neurons in the arcuate hypothalamic nuclei control food intake: proopiomelanocortin neurons activated by the anorexigenic (satiety) hormones and neurons activated by the orexigenic peptides that release neuropeptide Y and agouti-related peptide (hunger centre). The arcuate nucleus of the hypothalamus integrates hormonal inputs from the gut and adipose tissue (the anorexigenic hormones cholecystokinin, polypeptide YY, glucagon-like peptide-1, oxyntomodulin, leptin, and others) and orexigeneic peptides (ghrelin). Replicating the endocrine response to bariatric surgery through pharmacological mimicry holds promise for medical treatment. Obesity has genetic and environmental factors. New advances in genetic testing have identified both monogenic and polygenic obesity-related genes. Understanding the function of genes contributing to obesity will increase insights into the biology of obesity. This review includes the physiology of appetite control, the influence of genetics on obesity, and the changes that occur following bariatric surgery. This has the potential to lead to the development of more subtle, individualised, treatments for obesity.
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Affiliation(s)
- Indra Ramasamy
- Department of Blood Sciences, Conquest Hospital, Hastings TN37 7RD, UK
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Chen Z, Zhang P, Liu T, Qiu X, Li S, Lin JD. Neuregulin 4 mediates the metabolic benefits of mild cold exposure by promoting beige fat thermogenesis. JCI Insight 2024; 9:e172957. [PMID: 38015639 PMCID: PMC10906454 DOI: 10.1172/jci.insight.172957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 11/21/2023] [Indexed: 11/30/2023] Open
Abstract
Interorgan crosstalk via secreted hormones and metabolites is a fundamental aspect of mammalian metabolic physiology. Beyond the highly specialized endocrine cells, peripheral tissues are emerging as an important source of metabolic hormones that influence energy and nutrient metabolism and contribute to disease pathogenesis. Neuregulin 4 (Nrg4) is a fat-derived hormone that protects mice from nonalcoholic steatohepatitis (NASH) and NASH-associated liver cancer by shaping hepatic lipid metabolism and the liver immune microenvironment. Despite its enriched expression in brown fat, whether NRG4 plays a role in thermogenic response and mediates the metabolic benefits of cold exposure are areas that remain unexplored. Here we show that Nrg4 expression in inguinal white adipose tissue (iWAT) is highly responsive to chronic cold exposure. Nrg4 deficiency impairs beige fat induction and renders mice more susceptible to diet-induced metabolic disorders under mild cold conditions. Using mice with adipocyte and hepatocyte-specific Nrg4 deletion, we reveal that adipose tissue-derived NRG4, but not hepatic NRG4, is essential for beige fat induction following cold acclimation. Furthermore, treatment with recombinant NRG4-Fc fusion protein promotes beige fat induction in iWAT and improves metabolic health in mice with diet-induced obesity. These findings highlight a critical role of NRG4 in mediating beige fat induction and preserving metabolic health under mild cold conditions.
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Tang C, Li Q, Wang X, Yu Z, Ping X, Qin Y, Liu Y, Zheng L. Cardiac Timeless Trans-Organically Regulated by miR-276 in Adipose Tissue Modulates Cardiac Function. FUNCTION 2023; 5:zqad064. [PMID: 38058384 PMCID: PMC10696634 DOI: 10.1093/function/zqad064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/09/2023] [Accepted: 11/16/2023] [Indexed: 12/08/2023] Open
Abstract
The interconnection between cardiac function and circadian rhythms is of great importance. While the role of the biological clock gene Timeless (Tim) in circadian rhythm has been extensively studied, its impact on cardiac function remains largely been unexplored. Previous research has provided experimental evidence for the regulation of the heart by adipose tissue and the targeting of miR-276a/b on Timeless. However, the extent to which adipose tissue regulates cardiac Timeless genes trans-organically through miR-276a/b, and subsequently affects cardiac function, remains uncertain. Therefore, the objective of this study was to investigate the potential trans-organ modulation of the Timeless gene in the heart by adipose tissue through miR-276a/b. We found that cardiac-specific Timeless knockdown and overexpression resulted in a significant increase in heart rate (HR) and a significant decrease in Heart period (HP), diastolic intervals (DI), systolic intervals (SI), diastolic diameter (DD), and systolic diameter (SD). miR-276b systemic knockdown resulted in a significant increase in DI, arrhythmia index (AI), and fractional shortening (FS) significantly increased and SI, DD and SD significantly decreased. Adipose tissue-specific miR-276a/b knockdown and miR-276a overexpression resulted in a significant increase in HR and a significant decrease in DI and SI, which were improved by exercise intervention. This study presents a novel finding that highlights the significance of the heart circadian clock gene Timeless in heart function. Additionally, it demonstrates that adipose tissue exerts trans-organ modulation on the expression of the heart Timeless gene via miR-276a/b.
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Affiliation(s)
- Chao Tang
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - Qiufang Li
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - Xiaoya Wang
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - Zhengwen Yu
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - Xu Ping
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - yi Qin
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - Yang Liu
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
| | - Lan Zheng
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, 410012 Changsha, China
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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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Fried SK. Adipose 'neighborhoods' collaborate to maintain metabolic health. Curr Opin Genet Dev 2023; 81:102079. [PMID: 37406429 PMCID: PMC10867982 DOI: 10.1016/j.gde.2023.102079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 06/05/2023] [Accepted: 06/08/2023] [Indexed: 07/07/2023]
Abstract
Body fat is stored in anatomically distinct adipose depots that vary in their cell composition and play specialized roles in systemic metabolic homeostasis via secreted products. Their local effects on nearby tissues (e.g. the gut and visceral adipose tissues) are increasingly recognized and this local crosstalk is being elucidated. The major subcutaneous fat depots, abdominal and gluteal-femoral, exert opposite effects on the risk of metabolic disease. The pace of research into developmental, sex, and genetic determinants of human adipose depot growth and function is rapidly accelerating, providing insight into the pathogenesis of metabolic dysfunction in persons with obesity.
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Affiliation(s)
- Susan K Fried
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave Levy Place, Box 1152, New York, NY 10029, USA.
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