RESUMEN
Adipose tissue beiging refers to the process by which beige adipocytes emerge in classical white adipose tissue depots. Beige adipocytes dissipate chemical energy and secrete adipokines, such as classical brown adipocytes, to improve systemic metabolism, which is beneficial for people with obesity and metabolic diseases. Cold exposure and ß3-adrenergic receptor (AR) agonist treatment are two commonly used stimuli for increasing beige adipocytes in mice; however, their underlying biological processes are different. Transcriptional analysis of inguinal white adipose tissue (iWAT) has revealed that changes in extracellular matrix (ECM) pathway genes are specific to cold exposure. Hyaluronic acid (HA), a non-sulfated linear polysaccharide produced by nearly all cells, is one of the most common components of ECM. We found that cold exposure significantly increased iWAT HA levels, whereas the ß3-AR agonist CL316,243 did not. Increasing HA levels in iWAT by Has2 overexpression significantly increases cold-induced adipose tissue beiging; in contrast, decreasing HA by Spam1 overexpression, which encodes a hyaluronidase that digests HA, significantly decreases cold-induced iWAT beiging. All these data implicate a role of HA in promoting adipose tissue beiging, which is unique to cold exposure. Given the failure of ß3-AR agonists in clinical trials for obesity and metabolic diseases, increasing HA could serve as a new approach for recruiting more beige adipocytes to combat metabolic diseases.
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Tejido Adiposo Blanco , Frío , Ácido Hialurónico , Ácido Hialurónico/metabolismo , Animales , Ratones , Tejido Adiposo Blanco/metabolismo , Tejido Adiposo Blanco/efectos de los fármacos , Ratones Endogámicos C57BL , Masculino , Tejido Adiposo Beige/metabolismo , Adipocitos Beige/metabolismo , Adipocitos Beige/efectos de los fármacos , Matriz Extracelular/metabolismo , Dioxoles/farmacología , Receptores Adrenérgicos beta 3/metabolismo , Agonistas de Receptores Adrenérgicos beta 3/farmacologíaRESUMEN
Brown adipose tissue (BAT) and beige adipose tissues are important contributors to cold-induced whole body thermogenesis in rodents. The documentation in humans of cold- and ß-adrenergic receptor agonist-stimulated BAT glucose uptake using positron emission tomography (PET) and of a decrease of this response in individuals with cardiometabolic disorders led to the suggestion that BAT/beige adipose tissues could be relevant targets for prevention and treatment of these conditions. In this brief review, we will critically assess this question by first describing the basic rationale for this affirmation, second by examining the evidence in human studies, and third by discussing the possible means to activate the thermogenic response of these tissues in humans.
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Tejido Adiposo Beige , Tejido Adiposo Pardo , Termogénesis , Humanos , Tejido Adiposo Pardo/fisiología , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/efectos de los fármacos , Termogénesis/fisiología , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Beige/fisiología , Animales , Tomografía de Emisión de Positrones , Agonistas Adrenérgicos beta/farmacología , Obesidad/metabolismo , Obesidad/terapia , FríoRESUMEN
INTRODUCTION: Obesity, characterized by excess adipose tissue, is a major public health problem worldwide. Brown adipose tissue (BAT) and beige adipose tissue participate in thermogenesis through uncoupling protein 1 (UCP1). Polyphenols including those from Calafate (a native polyphenol-rich Patagonian berry), are considered as potential anti-obesity compounds due to their pro-thermogenic characteristics. However, polyphenols are mainly metabolized by the gut microbiota (GM) that may influence their bioactivity and bioavailability. The aim of this study was to determine the impact of dietary administration with a Calafate polyphenol-rich extract on thermogenic activity of BAT and beige adipose tissue and GM composition. METHODS: Eight-week-old C57BL6 mice (n = 30) were divided into 4 groups to receive for 24 weeks a control diet (C), a high-fat diet alone (HF), or high-fat diet supplemented with Calafate extract (HFC) or the same high-fat diet supplemented with Calafate extract but treated with antibiotics (HFCAB) from week 19-20. Administration with Calafate extract (50 mg/kg per day) was carried out for 3 weeks from week 21-23 in the HFC and HFCAB groups. After euthanasia, gene expression of thermogenic markers was analyzed in BAT and inguinal white adipose tissue (iWAT). Transmission electron microscopy was performed to assess mitochondrial morphology and cristae density in BAT. GM diversity and composition were characterized by deep sequencing with the MiSeq Illumina platform. RESULTS: Calafate extract administration had no effect on weight gain in mice fed a high-fat diet. However, it prevented alterations in mitochondrial cristae induced by HFD and increased Dio2 expression in BAT and iWAT. The intervention also influenced the GM composition, preventing changes in specific bacterial taxa induced by the high-fat diet. However, the antibiotic treatment prevented in part these effects, suggesting the implications of GM. CONCLUSION: These results suggest that the acute administration of a Calafate extract modulates the expression of thermogenic markers, prevents alterations in mitochondrial cristae and intestinal microbiota in preclinical models. The study highlights the complex interaction between polyphenols, thermogenesis, and the GM, providing valuable insights into their potential roles in the treatment of obesity-related metabolic diseases.
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Tejido Adiposo Pardo , Dieta Alta en Grasa , Microbioma Gastrointestinal , Ratones Endogámicos C57BL , Extractos Vegetales , Termogénesis , Animales , Microbioma Gastrointestinal/efectos de los fármacos , Termogénesis/efectos de los fármacos , Ratones , Tejido Adiposo Pardo/efectos de los fármacos , Tejido Adiposo Pardo/metabolismo , Extractos Vegetales/farmacología , Masculino , Obesidad/metabolismo , Proteína Desacopladora 1/metabolismo , Tejido Adiposo Beige/efectos de los fármacos , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Blanco/efectos de los fármacos , Tejido Adiposo Blanco/metabolismo , BiomarcadoresRESUMEN
Adipose tissue is conventionally recognized as a metabolic organ responsible for storing energy. However, a proportion of adipose tissue also functions as a thermogenic organ, contributing to the inhibition of weight gain and prevention of metabolic diseases. In recent years, there has been significant progress in the study of thermogenic fats, particularly brown adipose tissue (BAT). Despite this progress, the mechanism underlying thermogenesis in beige adipose tissue remains highly controversial. It is widely acknowledged that beige adipose tissue has three additional thermogenic mechanisms in addition to the conventional UCP1-dependent thermogenesis: Ca2+ cycling thermogenesis, creatine substrate cycling thermogenesis, and triacylglycerol/fatty acid cycling thermogenesis. This paper delves into these three mechanisms and reviews the latest advancements in the molecular regulation of thermogenesis from the molecular genetic perspective. The objective of this review is to provide readers with a foundation of knowledge regarding the beige fats and a foundation for future research into the mechanisms of this process, which may lead to the development of new strategies for maintaining human health.
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Adipocitos Beige , Termogénesis , Termogénesis/genética , Humanos , Adipocitos Beige/metabolismo , Animales , Proteína Desacopladora 1/metabolismo , Proteína Desacopladora 1/genética , Tejido Adiposo Pardo/metabolismo , Metabolismo Energético , Calcio/metabolismo , Ácidos Grasos/metabolismo , Triglicéridos/metabolismo , Tejido Adiposo Beige/metabolismoRESUMEN
Brown adipose tissue (BAT) is a heater organ that expresses thermogenic uncoupling protein 1 (UCP1) to maintain high body temperatures during cold stress. BAT thermogenesis is considered an overarching mammalian trait, but its evolutionary origin is unknown. We show that adipose tissue of marsupials, which diverged from eutherian mammals ~150 million years ago, expresses a nonthermogenic UCP1 variant governed by a partial transcriptomic BAT signature similar to that found in eutherian beige adipose tissue. We found that the reconstructed UCP1 sequence of the common eutherian ancestor displayed typical thermogenic activity, whereas therian ancestor UCP1 is nonthermogenic. Thus, mammalian adipose tissue thermogenesis may have evolved in two distinct stages, with a prethermogenic stage in the common therian ancestor linking UCP1 expression to adipose tissue and thermal stress. We propose that in a second stage, UCP1 acquired its thermogenic function specifically in eutherians, such that the onset of mammalian BAT thermogenesis occurred only after the divergence from marsupials.
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Tejido Adiposo Pardo , Evolución Biológica , Marsupiales , Termogénesis , Proteína Desacopladora 1 , Animales , Humanos , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Pardo/metabolismo , Euterios/genética , Euterios/fisiología , Evolución Molecular , Marsupiales/genética , Marsupiales/fisiología , Filogenia , Termogénesis/genética , Transcriptoma , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismoRESUMEN
Objectives: The effects of cold exposure on whole-body metabolism in humans have gained increasing attention. Brown or beige adipose tissues are crucial in cold-induced thermogenesis to dissipate energy and thus have the potential to combat metabolic disorders. Despite the immune regulation of thermogenic adipose tissues, the overall changes in vital immune cells during distinct cold periods remain elusive. This study aimed to discuss the overall changes in immune cells under different cold exposure periods and to screen several potential immune cell subpopulations on thermogenic regulation. Methods: Cibersort and mMCP-counter algorithms were employed to analyze immune infiltration in two (brown and beige) thermogenic adipose tissues under distinct cold periods. Changes in some crucial immune cell populations were validated by reanalyzing the single-cell sequencing dataset (GSE207706). Flow cytometry, immunofluorescence, and quantitative real-time PCR assays were performed to detect the proportion or expression changes in mouse immune cells of thermogenic adipose tissues under cold challenge. Results: The proportion of monocytes, naïve, and memory T cells increased, while the proportion of NK cells decreased under cold exposure in brown adipose tissues. Conclusion: Our study revealed dynamic changes in immune cell profiles in thermogenic adipose tissues and identified several novel immune cell subpopulations, which may contribute to thermogenic activation of adipose tissues under cold exposure.
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Tejido Adiposo Pardo , Frío , Termogénesis , Termogénesis/inmunología , Animales , Ratones , Tejido Adiposo Pardo/inmunología , Tejido Adiposo Pardo/metabolismo , Ratones Endogámicos C57BL , Masculino , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Beige/inmunología , Tejido Adiposo/inmunología , Tejido Adiposo/metabolismo , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Monocitos/inmunología , Monocitos/metabolismoRESUMEN
OBJECTIVE: Epicardial adipose tissue (EAT) is a visceral fat that has been associated with coronary artery disease and atrial fibrillation. Previous work has revealed that EAT exhibits beige features. METHODS: First, a new pan-genomic microarray analysis was performed on previously collected paired human EAT and thoracic subcutaneous AT (thSAT) from the EPICAR study (n = 31) to decipher a specific immune signature and its link with browning genes. Then, adaptive (T and B cells) and innate lymphoid cell (ILC1, ILC2, and ILC3) immunophenotyping assay panels, including CD127, CD117, and prostaglandin D2 receptor 2, were performed on prospectively collected paired human multiorgan donors (n = 18; INTERFACE study). RESULTS: In the EPICAR study, a positive correlation between the T helper cell subtype Th2 immune pathway and browning genes was found in EAT versus thSAT (r = 0.82; p < 0.0001). In the INTERFACE study, this correlation was also observed (r = 0.31; p = 0.017), and a preponderance of CD4+T cells, CD8+T cells, and a few B cells was observed in all ATs (p < 0.0001). An increase in ILCs was observed in visceral AT (VAT) (i.e., EAT + VAT; 30 ± 5 ILCs per gram of AT) compared with subcutaneous counterparts (i.e., thSAT + abdominal SAT; 8 ± 2 ILCs per gram of AT; p = 0.001), with ILC1 being the most frequent (ILC1 > ILC3 > ILC2). Numbers of ILCs per gram of AT correlated with several Th2 or browning genes (IL-13, TNF receptor superfamily member 9 [TNFRSF9], and alkaline phosphatase, biomineralization associated [ALPL]). Interestingly, a specific increase in EAT-ILC2 compared with other ATs was observed, including a significant proportion expressing CD69 and/or CD25 activation markers (97.9% ± 1.2%; p < 0.0001). Finally, more natural killer cells were observed in EAT + VAT than in thSAT + abdominal SAT (p = 0.01). Exclusion of patients with coronary artery disease in the EPICAR and INTERFACE studies did not modify the main findings. Gene expression phenotyping confirmed specific upregulation of Th2 pathway and browning genes (IL-33 and uncoupling protein 1 [UCP-1]) in EAT. CONCLUSIONS: This is the first study, to our knowledge, to provide a comparison between innate and adaptive lymphoid cells in human EAT. Further studies are ongoing to decipher whether these cells could be involved in EAT beiging.
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Inmunidad Innata , Linfocitos , Pericardio , Grasa Subcutánea , Humanos , Pericardio/metabolismo , Masculino , Grasa Subcutánea/metabolismo , Grasa Subcutánea/inmunología , Linfocitos/inmunología , Linfocitos/metabolismo , Femenino , Persona de Mediana Edad , Tejido Adiposo Beige/metabolismo , Adulto , Anciano , Inmunofenotipificación , Linfocitos B/inmunología , Linfocitos B/metabolismo , Células Th2/inmunología , Tejido Adiposo EpicárdicoRESUMEN
Brown adipose tissue (BAT) which is a critical regulator of energy homeostasis, and its activity is inhibited by obesity and low-grade chronic inflammation. Ginsenoside Rg3, the primary constituent of Korean red ginseng (steamed Panax ginseng CA Meyer), has shown therapeutic potential in combating inflammatory and metabolic diseases. However, it remains unclear whether Rg3 can protect against the suppression of browning or activation of BAT induced by inflammation. In this study, we conducted a screening of ginsenoside composition in red ginseng extract (RGE) and explored the anti-adipogenic effects of both RGE and Rg3. We observed that RGE (exist 0.25 mg/mL of Rg3) exhibited significant lipid-lowering effects in adipocytes during adipogenesis. Moreover, treatment with Rg3 (60 µM) led to the inhibition of triglyceride accumulation, subsequently promoting enhanced fatty acid oxidation, as evidenced by the conversion of radiolabeled 3H-fatty acids into 3H-H2O with mitochondrial activation. Rg3 alleviated the attenuation of browning in lipopolysaccharide (LPS)-treated beige adipocytes and primary brown adipocytes by recovered by uncoupling protein 1 (UCP1) and the oxygen consumption rate compared to the LPS-treated group. These protective effects of Rg3 on inflammation-induced inhibition of beige and BAT-derived thermogenesis were confirmed in vivo by treating with CL316,243 (a beta-adrenergic receptor agonist) and LPS to induce browning and inflammation, respectively. Consistent with the in vitro data, treatment with Rg3 (2.5 mg/kg, 8 weeks) effectively reversed the LPS-induced inhibition of brown adipocyte features in C57BL/6 mice. Our findings confirm that Rg3-rich foods are potential browning agents that counteract chronic inflammation and metabolic complications.
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Tejido Adiposo Pardo , Ginsenósidos , Lipopolisacáridos , Mitocondrias , Panax , Extractos Vegetales , Termogénesis , Ginsenósidos/farmacología , Animales , Termogénesis/efectos de los fármacos , Panax/química , Mitocondrias/metabolismo , Mitocondrias/efectos de los fármacos , Ratones , Extractos Vegetales/farmacología , Tejido Adiposo Pardo/efectos de los fármacos , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Beige/efectos de los fármacos , Ratones Endogámicos C57BL , Masculino , Adipogénesis/efectos de los fármacosRESUMEN
Obesity, characterized by the excessive accumulation of adipose tissue, has emerged as a major public health concern worldwide. To develop effective strategies for treating obesity, it is essential to comprehend the biological properties of different adipose tissue types and their respective roles in maintaining energy balance. Adipose tissue serves as a crucial organ for energy storage and metabolism in the human body, with functions extending beyond simple fat storage to encompass the regulation of energy homeostasis and the secretion of endocrine factors. This review provides an overview of the key characteristics, functional differences, and interconversion processes among white adipose tissue (WAT), brown adipose tissue (BAT), and beige adipose tissue. Moreover, it delves into the molecular mechanisms and recent research advancements concerning the browning of WAT, activation of BAT, and whitening of BAT. Although targeting adipose tissue metabolism holds promise as a potential approach for obesity treatment, further investigations are necessary to unravel the intricate biological features of various adipose tissue types and elucidate the molecular pathways governing their interconversion. Such research endeavors will pave the way for the development of more efficient and targeted therapeutic interventions in the fight against obesity.
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Tejido Adiposo Beige , Tejido Adiposo Pardo , Tejido Adiposo Blanco , Metabolismo Energético , Homeostasis , Obesidad , Humanos , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Blanco/metabolismo , Animales , Obesidad/metabolismo , Termogénesis , Tejido Adiposo/metabolismoRESUMEN
Glycogen is a form of energy storage for glucose in different tissues such as liver and skeletal muscle. It remains incompletely understood how glycogen impacts on adipose tissue functionality. Cold exposure elevated the expression of Gys1 that encodes glycogen synthase 1 in brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT). The in vivo function of Gys1 was analyzed using a mouse model in which Gys1 was deleted specifically in adipose tissues. Under normal chow conditions, Gys1 deletion caused little changes to body weight and glucose metabolism. Deletion of Gys1 abrogated upregulation of UCP1 and other thermogenesis-related genes in iWAT upon prolonged cold exposure or treatment with ß3-adrenergic receptor agonist CL-316,243. Stimulation of UCP1 by CL-316,243 in adipose-derived stromal cells (stromal vascular fractions, SVFs) was also reduced by Gys1 deletion. Both the basal glycogen content and CL-316,243-stimulated glycogen accumulation in adipose tissues were reduced by Gys1 deletion. High-fat diet-induced obesity and insulin resistance were aggravated in Gys1-deleted mice. The loss of body weight upon CL-316,243 treatment was also abrogated by the loss of Gys1. In conclusion, our results underscore the pivotal role of glycogen synthesis in adaptive thermogenesis in beige adipose tissue and its impact on diet-induced obesity in mice.NEW & NOTEWORTHY Glycogen is one of major types of fuel reserve in the body and its classical function is to maintain blood glucose level. This study uncovers that glycogen synthesis is required for beige fat tissue to generate heat upon cold exposure. Such a function of glycogen is linked to development of high-fat diet-induced obesity, thus extending our understanding about the physiological functions of glycogen.
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Tejido Adiposo Beige , Dieta Alta en Grasa , Glucógeno , Obesidad , Termogénesis , Animales , Termogénesis/genética , Termogénesis/fisiología , Ratones , Obesidad/metabolismo , Obesidad/genética , Tejido Adiposo Beige/metabolismo , Glucógeno/metabolismo , Glucógeno/biosíntesis , Masculino , Ratones Noqueados , Ratones Endogámicos C57BL , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Glucógeno Sintasa/metabolismo , Glucógeno Sintasa/genética , Frío , Adaptación Fisiológica , Proteína Desacopladora 1/metabolismo , Proteína Desacopladora 1/genéticaRESUMEN
Obesity and its associated complications pose a significant burden on health. The non-shivering thermogenesis (NST) and metabolic capacity properties of brown adipose tissue (BAT), which are distinct from those of white adipose tissue (WAT), in combating obesity and its related metabolic diseases has been well documented. However, beige adipose tissue, the third and relatively novel type of adipose tissue, which emerges in extensive presence of WAT and shares similar favorable metabolic properties with BAT, has garnered considerable attention in recent years. In this review, we focused on the role of G protein-coupled receptors (GPCRs), the largest receptor family and the most successful class of drug targets in humans, in the induction of beige adipocytes. More importantly, we highlight researchers' clinical treatment attempts to ameliorate obesity and other related metabolic diseases through the formation and activation of beige adipose tissue. In summary, this review provides valuable insights into the formation of beige adipose tissue and the involvement of GPCRs, based on the latest advancements in scientific research.
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Adipocitos Beige , Obesidad , Receptores Acoplados a Proteínas G , Termogénesis , Humanos , Receptores Acoplados a Proteínas G/metabolismo , Obesidad/metabolismo , Adipocitos Beige/metabolismo , Animales , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Pardo/metabolismoRESUMEN
PURPOSE OF REVIEW: By providing a concise overview of adipose tissue types, elucidating the regulation of adipose thermogenic capacity in both physiological contexts and chronic wasting diseases (a protracted hypermetabolic state that precipitates sustained catabolism and consequent progressive corporeal atrophy), and most importantly, delving into the ongoing discourse regarding the role of adipose tissue thermogenic activation in chronic wasting diseases, this review aims to provide researchers with a comprehensive understanding of the field. RECENT FINDINGS: Adipose tissue, traditionally classified as white, brown, and beige (brite) based on its thermogenic activity and potential, is intricately regulated by complex mechanisms in response to exercise or cold exposure. This regulation is adipose depot-specific and dependent on the duration of exposure. Excessive thermogenic activation of adipose tissue has been observed in chronic wasting diseases and has been considered a pathological factor that accelerates disease progression. However, this conclusion may be confounded by the detrimental effects of excessive lipolysis. Recent research also suggests that such activation may play a beneficial role in the early stages of chronic wasting disease and provide potential therapeutic effects. A more comprehensive understanding of the changes in adipose tissue thermogenesis under physiological and pathological conditions, as well as the underlying regulatory mechanisms, is essential for the development of novel interventions to improve health and prevent disease.
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Tejido Adiposo Pardo , Termogénesis , Humanos , Termogénesis/fisiología , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo/metabolismo , Tejido Adiposo Beige/metabolismo , Animales , Lipólisis , Ejercicio Físico/fisiología , Metabolismo Energético/fisiología , Tejido Adiposo Blanco/metabolismoRESUMEN
Epicardial adipose tissue (eAT) is a metabolically active fat depot that has been associated with a wide array of cardiac homeostatic functions and cardiometabolic diseases. A full understanding of its diverse physiological and pathological roles is hindered by the dearth of animal models. Here, we show, in the heart of an ectothermic teleost, the zebrafish, the existence of a fat depot localized underneath the epicardium, originating from the epicardium and exhibiting the molecular signature of beige adipocytes. Moreover, a subset of adipocytes within this cardiac fat tissue exhibits primitive thermogenic potential. Transcriptomic profiling and cross-species analysis revealed elevated glycolytic and cardiac homeostatic gene expression with downregulated obesity and inflammatory hallmarks in the teleost eAT compared to that of lean aged humans. Our findings unveil epicardium-derived beige fat in the heart of an ectotherm considered to possess solely white adipocytes for energy storage and identify pathways that may underlie age-driven remodeling of human eAT.
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Tejido Adiposo Beige , Pez Cebra , Animales , Humanos , Anciano , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Epicárdico , Tejido Adiposo/metabolismo , Pericardio/metabolismo , Termogénesis , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismoRESUMEN
BACKGROUND: Induction of beige fat for grafting is an emerging transplantation strategy. However, safety concerns associated with pharmaceutical interventions limit its wider application. Moreover, because beige fat is a special type of fat with strong metabolic functions, its effect on the metabolism of recipients after grafting has not been explored in the plastic surgery domain. OBJECTIVES: The aim of this study was to explore whether cold-induced inguinal white adipose tissue (iWAT) transplantation has a higher retention rate and beneficial effects on recipient metabolism. METHODS: C57/BL6 mice were subjected to cold stimulation for 48 hours to induce the browning of iWAT and harvested immediately. Subsequently, each mouse received a transplant of 0.2â mL cold-induced iWAT or normal iWAT. Fat grafts and recipients' iWAT, epididymal adipose tissue, and brown adipose tissue were harvested at 8 weeks after operation. Immunofluorescence staining, real-time polymerase chain reaction, and western blot were used for histological and molecular analysis. RESULTS: Cold-induced iWAT grafting had a higher mean [standard error of the mean] retention rate (67.33% [1.74%] vs 55.83% [2.94%], P < .01) and more satisfactory structural integrity than normal iWAT. Histological changes identified improved adipose tissue homeostasis after cold challenge, including abundant smaller adipocytes, higher levels of adipogenesis, angiogenesis, and proliferation, but lower levels of fibrosis. More importantly, cold-induced iWAT grafting suppressed the inflammation of epididymal adipose tissue caused by conventional fat grafting, and activated the glucose metabolism and thermogenic activity of recipients' adipose tissues. CONCLUSIONS: Cold-induced iWAT grafting is an effective nonpharmacological intervention strategy to improve the retention rate and homeostasis of grafts. Furthermore, it improves the adverse effects caused by traditional fat grafting, while also conferring metabolic benefits.
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Tejido Adiposo Pardo , Frío , Ratones Endogámicos C57BL , Grasa Subcutánea , Animales , Masculino , Grasa Subcutánea/trasplante , Grasa Subcutánea/metabolismo , Ratones , Tejido Adiposo Pardo/trasplante , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Tejido Adiposo Blanco/trasplante , Tejido Adiposo Beige/metabolismo , Supervivencia de InjertoRESUMEN
In the cold, the absence of the mitochondrial uncoupling protein 1 (UCP1) results in hyper-recruitment of beige fat, but classical brown fat becomes atrophied. Here we examine possible mechanisms underlying this phenomenon. We confirm that in brown fat from UCP1-knockout (UCP1-KO) mice acclimated to the cold, the levels of mitochondrial respiratory chain proteins were diminished; however, in beige fat, the mitochondria seemed to be unaffected. The macrophages that accumulated massively not only in brown fat but also in beige fat of the UCP1-KO mice acclimated to cold did not express tyrosine hydroxylase, the norepinephrine transporter (NET) and monoamine oxidase-A (MAO-A). Consequently, they could not influence the tissues through the synthesis or degradation of norepinephrine. Unexpectedly, in the cold, both brown and beige adipocytes from UCP1-KO mice acquired an ability to express MAO-A. Adipose tissue norepinephrine was exclusively of sympathetic origin, and sympathetic innervation significantly increased in both tissues of UCP1-KO mice. Importantly, the magnitude of sympathetic innervation and the expression levels of genes induced by adrenergic stimulation were much higher in brown fat. Therefore, we conclude that no qualitative differences in innervation or macrophage character could explain the contrasting reactions of brown versus beige adipose tissues to UCP1-ablation. Instead, these contrasting responses may be explained by quantitative differences in sympathetic innervation: the beige adipose depot from the UCP1-KO mice responded to cold acclimation in a canonical manner and displayed enhanced recruitment, while the atrophy of brown fat lacking UCP1 may be seen as a consequence of supraphysiological adrenergic stimulation in this tissue.
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Tejido Adiposo Beige , Tejido Adiposo Pardo , Sistema Nervioso Simpático , Termogénesis , Proteína Desacopladora 1 , Animales , Ratones , Tejido Adiposo Beige/inervación , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Pardo/inervación , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Adrenérgicos/metabolismo , Monoaminooxidasa/genética , Monoaminooxidasa/metabolismo , Norepinefrina/metabolismo , Termogénesis/genética , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo , Ratones Noqueados , Aclimatación/genética , Sistema Nervioso Simpático/fisiología , Macrófagos/metabolismoRESUMEN
Global health concerns about micro- and nanoplastics are increasing. The newly discovered beige adipocytes play a vital role in energy homeostasis through their high thermogenic capacity upon activation. However, the effects of micro- and nanoplastics on beige adipocytes have not yet been studied. We investigated whether the effects of oral exposure to polystyrene nanoparticles (PS-NPs) on systemic metabolic performance can be induced by disrupting beige adipocyte function, and the potential mechanism. In the present study, C57BL/6J male mice were fed a high-fat diet (HFD) with or without PS-NPs exposure for 12 weeks to investigate the differences in metabolic performance. We also isolated stromal vascular fraction from C57BL/6J male mice to differentiate and prepare primary beige adipocyte cultures. Primary beige adipocytes were treated with PS-NPs on the sixth day of differentiation. The results showed that oral intake of PS-NPs exacerbated metabolic disorders of mice under HFD, including suppressed energy expenditure, increased fat mass and liver steatosis, decreased insulin sensitivity, disrupted glucose homeostasis, and decreased cold-tolerance capability compared with the control group. Intriguingly, we observed that, after a 12-week exposure, PS-NPs accumulated in the inguinal white adipose tissue (iWAT), a fat depot rich in beige adipocytes, further suppressing thermogenic gene programs, particularly the level of uncoupling protein 1 (UCP1), a master regulator in the browning process of beige adipocytes. These effects ultimately led to decreased energy expenditure and subsequent disorders of glucolipid metabolism. Mechanistically, we revealed that PS-NPs disrupt mitochondrial function and induce oxidative damage and inflammation in beige adipocytes to inhibit their function. These negative metabolic effects of PS-NPs were ameliorated by antioxidant supplementation. Our study is the first to demonstrate that PS-NPs exposure exacerbates metabolic disorder in HFD-fed mice by disrupting beige adipocyte function.
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Resistencia a la Insulina , Obesidad , Ratones , Masculino , Animales , Obesidad/metabolismo , Poliestirenos/toxicidad , Microplásticos , Dieta Alta en Grasa/efectos adversos , Tejido Adiposo Beige/metabolismo , Ratones Endogámicos C57BLRESUMEN
In mammals, brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT) execute sequential thermogenesis to maintain body temperature during cold stimuli. BAT rapidly generates heat through brown adipocyte activation, and further iWAT gradually stimulates beige fat cell differentiation upon prolonged cold challenges. However, fat depot-specific regulatory mechanisms for thermogenic activation of two fat depots are poorly understood. Here, we demonstrate that E3 ubiquitin ligase RNF20 orchestrates adipose thermogenesis with BAT- and iWAT-specific substrates. Upon cold stimuli, BAT RNF20 is rapidly downregulated, resulting in GABPα protein elevation by controlling protein stability, which stimulates thermogenic gene expression. Accordingly, BAT-specific Rnf20 suppression potentiates BAT thermogenic activity via GABPα upregulation. Moreover, upon prolonged cold stimuli, iWAT RNF20 is gradually upregulated to promote de novo beige adipogenesis. Mechanistically, iWAT RNF20 mediates NCoR1 protein degradation, rather than GABPα, to activate PPARγ. Together, current findings propose fat depot-specific regulatory mechanisms for temporal activation of adipose thermogenesis.
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Tejido Adiposo Beige , Tejido Adiposo Pardo , Ubiquitina-Proteína Ligasas , Animales , Humanos , Ratones , Adipocitos Marrones/metabolismo , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Frío , Ligasas/metabolismo , Mamíferos , Ratones Endogámicos C57BL , Obesidad/metabolismo , Termogénesis , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Enhancing the development of and thermogenesis in brown and beige fat represents a potential treatment for obesity. In this study, we show that Foxj3 expression in fat is stimulated by cold exposure and a ß-adrenergic agonist. Adipose-specific Foxj3 knockout impaired the thermogenic function of brown fat, leading to morphological whitening of brown fat and obesity. Adipose Foxj3-deficient mice displayed increased fasting blood glucose levels and hepatic steatosis while on a chow diet. Foxj3 deficiency inhibited the browning of inguinal white adipose tissue (iWAT) following ß3-agonist treatment of mice. Furthermore, depletion of Foxj3 in primary brown adipocytes reduced the expression of thermogenic genes and cellular respiration, indicating that the Foxj3 effects on the thermogenic program are cell autonomous. In contrast, Foxj3 overexpression in primary brown adipocytes enhanced the thermogenic program. Moreover, AAV-mediated Foxj3 overexpression in brown fat and iWAT increased energy expenditure and improved systemic metabolism on either a chow or high-fat diet. Finally, Foxj3 deletion in fat inhibited the ß3-agonist-mediated induction of WAT browning and brown adipose tissue thermogenesis. Mechanistically, cold-inducible Foxj3 stimulated the expression of PGC-1α and UCP1, subsequently promoting energy expenditure. This study identifies Foxj3 as a critical regulator of fat thermogenesis, and targeting Foxj3 in fat might be a therapeutic strategy for treating obesity and metabolic diseases.
Asunto(s)
Tejido Adiposo Beige , Tejido Adiposo Pardo , Ratones , Animales , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Adipocitos Marrones/metabolismo , Metabolismo Energético/genética , Obesidad/genética , Obesidad/metabolismo , Termogénesis/genética , Ratones Endogámicos C57BLRESUMEN
Adipose tissue, including white adipose tissue (WAT), brown adipose tissue (BAT), and beige adipose tissue, is vital in modulating whole-body energy metabolism. While WAT primarily stores energy, BAT dissipates energy as heat for thermoregulation. Beige adipose tissue is a hybrid form of adipose tissue that shares characteristics with WAT and BAT. Dysregulation of adipose tissue metabolism is linked to various disorders, including obesity, type 2 diabetes, cardiovascular diseases, cancer, and infertility. Both brown and beige adipocytes secrete multiple molecules, such as batokines, packaged in extracellular vesicles or as soluble signaling molecules that play autocrine, paracrine, and endocrine roles. A greater understanding of the adipocyte secretome is essential for identifying novel molecular targets in treating metabolic disorders. Additionally, microRNAs show crucial roles in regulating adipose tissue differentiation and function, highlighting their potential as biomarkers for metabolic disorders. The browning of WAT has emerged as a promising therapeutic approach in treating obesity and associated metabolic disorders. Many browning agents have been identified, and nanotechnology-based drug delivery systems have been developed to enhance their efficacy. This review scrutinizes the characteristics of and differences between white, brown, and beige adipose tissues, the molecular mechanisms involved in the development of the adipocytes, the significant roles of batokines, and regulatory microRNAs active in different adipose tissues. Finally, the potential of WAT browning in treating obesity and atherosclerosis, the relationship of BAT with cancer and fertility disorders, and the crosstalk between adipose tissue with circadian system and circadian disorders are also investigated.