RESUMO
Beige and brown fat consume glucose and lipids to produce heat, using uncoupling protein 1 (UCP1). It is thought that full activation of brown adipose tissue (BAT) may increase total daily energy expenditure by 20%. Humans normally have more beige and potentially beige-able fat than brown fat. Strategies to increase beige fat differentiation and activation may be useful for the treatment of obesity and diabetes. Mice were fed chow or high-fat diet (HFD) with or without the iron chelator deferasirox. Animals fed HFD + deferasirox were markedly lighter than their HFD controls with increased energy expenditure (12% increase over 24 h, p < 0.001). Inguinal fat from HFD + deferasirox mice showed increased beige fat quantity with greater Ucp1 and Prdm16 expression. Inguinal adipose tissue explants were studied in a Seahorse bioanalyser and energy expenditure was significantly increased. Deferasirox was also effective in established obesity and in ob/ob mice, indicating that intact leptin signalling is not needed for efficacy. These studies identify iron chelation as a strategy to preferentially activate beige fat. Whether activating brown/beige fat is effective in humans is unproven. However, depleting iron to low-normal levels is a potential therapeutic strategy to improve obesity and related metabolic disorders, and human studies may be warranted.
Assuntos
Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/metabolismo , Diferenciação Celular/efeitos dos fármacos , Deferasirox/farmacologia , Quelantes de Ferro/farmacologia , Obesidade/tratamento farmacológico , Obesidade/prevenção & controle , Animais , Deferasirox/uso terapêutico , Dieta Hiperlipídica/efeitos adversos , Glucose/metabolismo , Humanos , Quelantes de Ferro/uso terapêutico , Metabolismo dos Lipídeos , Camundongos , Obesidade/etiologia , Obesidade/metabolismo , Termogênese , Proteína Desacopladora 1/metabolismoRESUMO
Brown and beige adipose tissue are emerging as distinct endocrine organs. These tissues are functionally associated with skeletal muscle, adipose tissue metabolism and systemic energy expenditure, suggesting an interorgan signaling network. Using metabolomics, we identify 3-methyl-2-oxovaleric acid, 5-oxoproline, and ß-hydroxyisobutyric acid as small molecule metabokines synthesized in browning adipocytes and secreted via monocarboxylate transporters. 3-methyl-2-oxovaleric acid, 5-oxoproline and ß-hydroxyisobutyric acid induce a brown adipocyte-specific phenotype in white adipocytes and mitochondrial oxidative energy metabolism in skeletal myocytes both in vitro and in vivo. 3-methyl-2-oxovaleric acid and 5-oxoproline signal through cAMP-PKA-p38 MAPK and ß-hydroxyisobutyric acid via mTOR. In humans, plasma and adipose tissue 3-methyl-2-oxovaleric acid, 5-oxoproline and ß-hydroxyisobutyric acid concentrations correlate with markers of adipose browning and inversely associate with body mass index. These metabolites reduce adiposity, increase energy expenditure and improve glucose and insulin homeostasis in mouse models of obesity and diabetes. Our findings identify beige adipose-brown adipose-muscle physiological metabokine crosstalk.
Assuntos
Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/metabolismo , Metabolismo Energético/genética , Homeostase/genética , Transdução de Sinais/genética , Adipócitos Marrons/metabolismo , Adipócitos Brancos/metabolismo , Tecido Adiposo Bege/citologia , Tecido Adiposo Marrom/citologia , Animais , Linhagem Celular , Células Cultivadas , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Perfilação da Expressão Gênica/métodos , Humanos , Masculino , Espectrometria de Massas , Metabolômica/métodos , Camundongos Endogâmicos C57BLRESUMO
Adipose tissue expansion, as seen in obesity, is often metabolically detrimental causing insulin resistance and the metabolic syndrome. However, white adipose tissue expansion at early ages is essential to establish a functional metabolism. To understand the differences between adolescent and adult adipose tissue expansion, we studied the cellular composition of the stromal vascular fraction of subcutaneous adipose tissue of two and eight weeks old mice using single cell RNA sequencing. We identified a subset of adolescent preadipocytes expressing the mature white adipocyte marker Asc-1 that showed a low ability to differentiate into beige adipocytes compared to Asc-1 negative cells in vitro. Loss of Asc-1 in subcutaneous preadipocytes resulted in spontaneous differentiation of beige adipocytes in vitro and in vivo. Mechanistically, this was mediated by a function of the amino acid transporter ASC-1 specifically in proliferating preadipocytes involving the intracellular accumulation of the ASC-1 cargo D-serine.
Assuntos
Adipócitos Bege/metabolismo , Adipócitos Brancos/metabolismo , Tecido Adiposo Bege/crescimento & desenvolvimento , Tecido Adiposo Branco/crescimento & desenvolvimento , Sistema y+ de Transporte de Aminoácidos/metabolismo , Adipócitos Bege/citologia , Adipócitos Brancos/citologia , Tecido Adiposo Bege/citologia , Tecido Adiposo Branco/citologia , Sistema y+ de Transporte de Aminoácidos/genética , Animais , Sequência de Bases , Diferenciação Celular/genética , Células Cultivadas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Análise de Sequência de RNA , Análise de Célula Única , Proteína Desacopladora 1/biossínteseRESUMO
Cold- and diet-induced recruitment of brown adipose tissue (BAT) and the browning of white adipose tissue (WAT) are dynamic processes, and the recruited state attained is a state of dynamic equilibrium, demanding continuous stimulation to be maintained. An involvement of macrophages, classical proinflammatory (M1) or alternatively activated anti-inflammatory (M2), is presently discussed as being an integral part of these processes. If these macrophages play a mediatory role in the recruitment process, such an involvement would have to be maintained in the recruited state. We have, therefore, investigated whether the recruited state of these tissues is associated with macrophage accretion or attrition. We found no correlation (positive or negative) between total UCP1 mRNA levels (as a measure of recruitment) and proinflammatory macrophages in any adipose depot. We found that in young chow-fed mice, cold-induced recruitment correlated with accretion of anti-inflammatory macrophages; however, such a correlation was not seen when cold-induced recruitment was studied in diet-induced obese mice. Furthermore, the anti-inflammatory macrophage accretion was mediated via ß1/ß2-adrenergic receptors; yet, in their absence, and thus in the absence of macrophage accretion, recruitment proceeded normally. We thus conclude that the classical recruited state in BAT and inguinal (brite/beige) WAT is not paralleled by macrophage accretion or attrition. Our results make mediatory roles for macrophages in the recruitment process less likely.NEW & NOTEWORTHY A regulatory or mediatory role-positive or negative-for macrophages in the recruitment of brown adipose tissue is presently discussed. As the recruited state in the tissue is a dynamic process, maintenance of the recruited state would need persistent alterations in macrophage complement. Contrary to this expectation, we demonstrate here an absence of alterations in macrophage complement in thermogenically recruited brown-or brite/beige-adipose tissues. Macrophage regulation of thermogenic capacity is thus less likely.
Assuntos
Tecido Adiposo Bege/fisiologia , Tecido Adiposo Marrom/fisiologia , Macrófagos/fisiologia , Receptores Adrenérgicos beta 1/fisiologia , Receptores Adrenérgicos beta 2/fisiologia , Termogênese , Tecido Adiposo Bege/citologia , Tecido Adiposo Marrom/citologia , Animais , Dieta/efeitos adversos , Regulação da Expressão Gênica , Macrófagos/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/etiologia , Obesidade/metabolismo , Obesidade/patologia , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismoRESUMO
Brown adipose tissue (BAT) is a thermogenic organ in rodents and humans. In mice, the transplantation of BAT has been successfully used to combat obesity and its comorbidities. While such beneficial properties of BAT are now evident, the developmental and cellular origins of brown, beige, and white adipocytes have remained only poorly understood, especially in humans. We recently discovered that CD90 is highly expressed in stromal cells isolated from human white adipose tissue (WAT) compared to BAT. Here, we studied whether CD90 interferes with brown or white adipogenesis or white adipocyte beiging. We applied flow cytometric sorting of human adipose tissue stromal cells (ASCs), a CRISPR/Cas9 knockout strategy in the human Simpson-Golabi-Behmel syndrome (SGBS) adipocyte model system, as well as a siRNA approach in human approaches supports the hypothesis that CD90 affects brown or white adipogenesis or white adipocyte beiging in humans. Taken together, our findings call the conclusions drawn from previous studies, which claimed a central role of CD90 in adipocyte differentiation, into question.
Assuntos
Tecido Adiposo Bege/citologia , Tecido Adiposo Marrom/citologia , Arritmias Cardíacas/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Gigantismo/genética , Cardiopatias Congênitas/genética , Deficiência Intelectual/genética , Antígenos Thy-1/genética , Antígenos Thy-1/metabolismo , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/citologia , Tecido Adiposo Branco/metabolismo , Adulto , Arritmias Cardíacas/metabolismo , Sistemas CRISPR-Cas , Diferenciação Celular , Células Cultivadas , Feminino , Citometria de Fluxo , Técnicas de Inativação de Genes , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Gigantismo/metabolismo , Cardiopatias Congênitas/metabolismo , Humanos , Deficiência Intelectual/metabolismo , Masculino , Pessoa de Meia-Idade , Células Estromais/metabolismo , Termogênese , Regulação para CimaRESUMO
Adipose tissues dynamically remodel their cellular composition in response to external cues by stimulating beige adipocyte biogenesis; however, the developmental origin and pathways regulating this process remain insufficiently understood owing to adipose tissue heterogeneity. Here, we employed single-cell RNA-seq and identified a unique subset of adipocyte progenitor cells (APCs) that possessed the cell-intrinsic plasticity to give rise to beige fat. This beige APC population is proliferative and marked by cell-surface proteins, including PDGFRα, Sca1, and CD81. Notably, CD81 is not only a beige APC marker but also required for de novo beige fat biogenesis following cold exposure. CD81 forms a complex with αV/ß1 and αV/ß5 integrins and mediates the activation of integrin-FAK signaling in response to irisin. Importantly, CD81 loss causes diet-induced obesity, insulin resistance, and adipose tissue inflammation. These results suggest that CD81 functions as a key sensor of external inputs and controls beige APC proliferation and whole-body energy homeostasis.
Assuntos
Adipogenia/genética , Tecido Adiposo Bege/metabolismo , Metabolismo Energético/genética , Quinase 1 de Adesão Focal/metabolismo , Transdução de Sinais/genética , Células-Tronco/metabolismo , Tetraspanina 28/metabolismo , Adipócitos/metabolismo , Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/crescimento & desenvolvimento , Tecido Adiposo Branco/metabolismo , Adulto , Animais , Ataxina-1/metabolismo , Feminino , Fibronectinas/farmacologia , Quinase 1 de Adesão Focal/genética , Humanos , Inflamação/genética , Inflamação/metabolismo , Resistência à Insulina/genética , Integrinas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Obesidade/genética , Obesidade/metabolismo , RNA-Seq , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Análise de Célula Única , Células-Tronco/citologia , Tetraspanina 28/genéticaRESUMO
The receptor activator of nuclear factor-κB (NF-κB) (RANK), its ligand (RANKL), and the decoy receptor osteoprotegerin (OPG) are a triad of proteins that regulate bone metabolism, and serum OPG is considered a biomarker for cardiovascular diseases and Type 2 diabetes; however, the implications of OPG in adipose tissue metabolism remains elusive. In this study, we investigate RANK-RANKL-OPG signaling in white adipose tissue browning. Histological analysis of osteoprotegerin knockout (OPG-/-) mice showed subcutaneous white adipose tissue (sWAT) browning, resistance for high-fat diet-induced weight gain, and preserved glucose metabolism compared with wild-type (WT) mice. Stromal vascular fraction (SVF) cells from sWAT of OPG-/- mice showed multilocular morphology and higher expression of brown adipocyte marker genes compared with those from the WT group. Infusion of RANKL induced browning and elevated respiratory rates in sWAT, along with increased whole body oxygen consumption in mice measured by indirect calorimetry. Subcutaneous WAT-derived SVF and 3T3-L1 cells, but not mature white adipocytes, differentiated into beige adipose tissue in the presence of RANKL. Moreover, SVF cells, even under white adipocyte differentiation, showed multilocular lipid droplet, lower lipid content, and increased expression of beige adipocyte markers with RANKL stimulation. In this study, we show for the first time the contribution of RANKL to increase energy expenditure by inducing beige adipocyte differentiation in preadipocytes.
Assuntos
Adipócitos Bege/metabolismo , Adipogenia/genética , Tecido Adiposo Branco/metabolismo , Obesidade/metabolismo , Osteoprotegerina/genética , Ligante RANK/metabolismo , Receptor Ativador de Fator Nuclear kappa-B/metabolismo , Células 3T3-L1 , Adipócitos Bege/citologia , Adipócitos Bege/ultraestrutura , Adipócitos Brancos/citologia , Adipócitos Brancos/metabolismo , Adipócitos Brancos/ultraestrutura , Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Branco/citologia , Animais , Calorimetria Indireta , Dieta Hiperlipídica , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/genética , Gotículas Lipídicas/ultraestrutura , Camundongos , Camundongos Knockout , Osteoprotegerina/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Consumo de Oxigênio/genética , Ligante RANK/farmacologia , Transdução de Sinais , Gordura Subcutânea/efeitos dos fármacos , Gordura Subcutânea/metabolismo , Aumento de Peso/efeitos dos fármacos , Aumento de Peso/genéticaRESUMO
Metabolites of omega-6 and omega-3 polyunsaturated fatty acids are important signaling molecules implicated in the control of adipogenesis and energy balance regulation. Some of these metabolites belonging to the group of oxylipins have been associated with non-shivering thermogenesis in mice mediated by brown or brite adipose tissue. We aimed to identify novel molecules with thermogenic potential and to clarify the relevance of these findings in a translational context. Therefore, we characterized and compared the oxylipin profiles of murine and human adipose tissues with different abundance of brown or brite adipocytes. A broad panel of 36 fatty acid metabolites was quantified in brown and white adipose tissues of C57BL/6J mice acclimatized to different ambient temperatures and in biopsies of human supraclavicular brown and white adipose tissue. The oxylipin profile of murine brite adipose tissue was not distinguishable from white adipose tissue, suggesting that adipose tissue browning in vivo is not associated with major changes in the oxylipin metabolism. Human brown and white adipose tissue also exhibited similar metabolite profiles. This is in line with previous studies proposing human brown adipose tissue to resemble the nature of murine brite adipose tissue representing a heterogeneous mixture of brite and white adipocytes. Although the global oxylipin profile served as a marker for the abundance of thermogenic adipocytes in bona fide brown but not white adipose tissue, we identified 5-HETE and 5,6-EET as individual compounds consistently associated with the abundance of brown or brite adipocytes in human BAT and murine brite fat. Further studies need to establish whether these candidates are mere markers or functional effectors of thermogenic capacity.
Assuntos
Adipogenia , Tecido Adiposo Bege/citologia , Tecido Adiposo Marrom/citologia , Biomarcadores/metabolismo , Ácidos Graxos/metabolismo , Metaboloma , Oxilipinas/metabolismo , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/metabolismo , Animais , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , TermogêneseRESUMO
Thermogenic (brown and beige) adipose tissues improve glucose and lipid homeostasis and therefore represent putative targets to cure obesity and related metabolic diseases including type II diabetes. Beside decades of research and the very well-described role of noradrenergic signaling, mechanisms underlying adipocytes plasticity and activation of thermogenic adipose tissues remain incompletely understood. Recent studies show that metabolites such as lactate control the oxidative capacity of thermogenic adipose tissues. Long time viewed as a metabolic waste product, lactate is now considered as an important metabolic substrate largely feeding the oxidative metabolism of many tissues, acting as a signaling molecule and as an inter-cellular and inter-tissular redox carrier. In this review, we provide an overview of the recent findings highlighting the importance of lactate in adipose tissues, from its production to its role as a browning inducer and its metabolic links with brown adipose tissue. We also discuss additional function(s) than thermogenesis ensured by brown and beige adipose tissues, i.e., their ability to dissipate high redox pressure and oxidative stress thanks to the activity of the uncoupling protein-1, helping to maintain tissue and whole organism redox homeostasis and integrity.
Assuntos
Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/metabolismo , Ácido Láctico/metabolismo , Proteína Desacopladora 1/metabolismo , Tecido Adiposo Bege/citologia , Tecido Adiposo Marrom/citologia , Animais , Metabolismo Energético , Humanos , Oxirredução , Estresse Oxidativo , TermogêneseRESUMO
Since the rediscovery of active brown and beige adipose tissues in humans a decade ago, great efforts have been made to identify the mechanisms underlying the activation and inactivation of these tissues, with the hope of designing potential strategies to fight against obesity and associated metabolic disorders such as type 2 diabetes. Active brown/beige fat increases the energy expenditure and is associated with reduced hyperglycemia and hyperlipidemia, whereas its atrophy and inactivation have been associated with obesity and aging. Autophagy, which is the process by which intracellular components are degraded within the lysosomes, has recently emerged as an important regulatory mechanism of brown/beige fat plasticity. Studies have shown that autophagy participates in the intracellular remodeling events that occur during brown/beige adipogenesis, thermogenic activation, and inactivation. The autophagic degradation of mitochondria appears to be important for the inactivation of brown fat and the transition from beige-to-white adipose tissue. Moreover, autophagic dysregulation in adipose tissues has been associated with obesity. Thus, understanding the regulatory mechanisms that control autophagy in the physiology and pathophysiology of adipose tissues might suggest novel treatments against obesity and its associated metabolic diseases.
Assuntos
Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/metabolismo , Autofagia , Doenças Metabólicas/metabolismo , Obesidade/metabolismo , Adipogenia , Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/patologia , Tecido Adiposo Marrom/citologia , Tecido Adiposo Marrom/patologia , Animais , Humanos , Mitocôndrias/metabolismo , TermogêneseRESUMO
Energy consuming, heat-producing beige adipocytes, located in classic white adipose tissue (WAT), hold promise for the treatment of obesity. Few reports have quantitatively assessed the contribution of browned 'WAT' to energy expenditure. There is a need for methods to examine beige-fat thermogenesis, independently of classical brown fat. The aim of this study is to optimize an inducible lentiviral shRNA to conditionally knock-down Ucp1 and assess the effects on 'browned' WAT. Primary adipocytes from mouse inguinal WAT converted into thermogenic adipocytes when stimulated with ß-adrenergic agonist and thiazolidinedione. There was increased UCP1 protein and importantly increases in various indicators of mitochondrial bioenergetics. Next, we determined optimal transfection conditions for the UCP1-shRNA lentiviral system and subsequently applied this to 'browned' WAT. UCP1 knockdown decreased the brown/beige-fat gene profile and decreased mitochondrial respiration. In summary, this study optimizes lentiviral UCP1-shRNA technology in vitro. This technique could be applied to inguinal fat depots in vivo. This would allow investigation of contribution of depots to whole-body metabolism to help elucidate the physiological relevance of beige fat.
Assuntos
Tecido Adiposo Bege/metabolismo , Metabolismo Energético/genética , Homeostase/genética , Lentivirus/genética , Interferência de RNA , Proteína Desacopladora 1/deficiência , Proteína Desacopladora 1/genética , Adipócitos/metabolismo , Tecido Adiposo Bege/citologia , Animais , Glicólise/genética , Masculino , Camundongos Endogâmicos C57BL , RNA Interferente Pequeno/genética , Termogênese/genéticaRESUMO
Tonicity-responsive enhancer binding protein (TonEBP or NFAT5) is a regulator of cellular adaptation to hypertonicity, macrophage activation and T-cell development. Here we report that TonEBP is an epigenetic regulator of thermogenesis and obesity. In mouse subcutaneous adipocytes, TonEBP expression increases > 50-fold in response to high-fat diet (HFD) feeding. Mice with TonEBP haplo-deficiency or adipocyte-specific TonEBP deficiency are resistant to HFD-induced obesity and metabolic defects (hyperglycemia, hyperlipidemia, and hyperinsulinemia). They also display increased oxygen consumption, resistance to hypothermia, and beiging of subcutaneous fat tissues. TonEBP suppresses the promoter of ß3-adrenoreceptor gene, a critical regulator of lipolysis and thermogenesis, in ex vivo and cultured adipocytes. This involves recruitment of DNMT1 DNA methylase and methylation of the promoter. In human subcutaneous adipocytes TonEBP expression displays a correlation with body mass index but an inverse correlation with ß3-adrenoreceptor expression. Thus, TonEBP is an attractive therapeutic target for obesity, insulin resistance, and hyperlipidemia.
Assuntos
Epigênese Genética , Resistência à Insulina/genética , Obesidade/metabolismo , Fatores de Transcrição/metabolismo , Células 3T3 , Adipócitos/metabolismo , Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/metabolismo , Animais , Índice de Massa Corporal , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Metilação de DNA/genética , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Metabolismo Energético/genética , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Transgênicos , MicroRNAs/genética , MicroRNAs/metabolismo , Obesidade/etiologia , Cultura Primária de Células , Receptores Adrenérgicos beta 3/metabolismo , Gordura Subcutânea/citologia , Gordura Subcutânea/metabolismo , Termogênese/genética , Fatores de Transcrição/genéticaRESUMO
Brown adipose tissue (BAT) is able to rapidly generate heat and metabolise macronutrients, such as glucose and lipids, through activation of mitochondrial uncoupling protein 1 (UCP1). Diet can modulate UCP1 function but the capacity of individual nutrients to promote the abundance and activity of UCP1 is not well established. Caffeine consumption has been associated with loss of body weight and increased energy expenditure, but whether it can activate UCP1 is unknown. This study examined the effect of caffeine on BAT thermogenesis in vitro and in vivo. Stem cell-derived adipocytes exposed to caffeine (1 mM) showed increased UCP1 protein abundance and cell metabolism with enhanced oxygen consumption and proton leak. These functional responses were associated with browning-like structural changes in mitochondrial and lipid droplet content. Caffeine also increased peroxisome proliferator-activated receptor gamma coactivator 1-alpha expression and mitochondrial biogenesis, together with a number of BAT selective and beige gene markers. In vivo, drinking coffee (but not water) stimulated the temperature of the supraclavicular region, which co-locates to the main region of BAT in adult humans, and is indicative of thermogenesis. Taken together, these results demonstrate that caffeine can promote BAT function at thermoneutrality and may have the potential to be used therapeutically in adult humans.
Assuntos
Tecido Adiposo Marrom/citologia , Tecido Adiposo Marrom/efeitos dos fármacos , Cafeína/farmacologia , Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/efeitos dos fármacos , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/metabolismo , Animais , Metabolismo Energético/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Células-Tronco Mesenquimais/citologia , Camundongos , Biogênese de Organelas , Temperatura , Proteína Desacopladora 1/genéticaRESUMO
Environmental cues profoundly affect cellular plasticity in multicellular organisms. For instance, exercise promotes a glycolytic-to-oxidative fibre-type switch in skeletal muscle, and cold acclimation induces beige adipocyte biogenesis in adipose tissue. However, the molecular mechanisms by which physiological or pathological cues evoke developmental plasticity remain incompletely understood. Here we report a type of beige adipocyte that has a critical role in chronic cold adaptation in the absence of ß-adrenergic receptor signalling. This beige fat is distinct from conventional beige fat with respect to developmental origin and regulation, and displays enhanced glucose oxidation. We therefore refer to it as glycolytic beige fat. Mechanistically, we identify GA-binding protein α as a regulator of glycolytic beige adipocyte differentiation through a myogenic intermediate. Our study reveals a non-canonical adaptive mechanism by which thermal stress induces progenitor cell plasticity and recruits a distinct form of thermogenic cell that is required for energy homeostasis and survival.
Assuntos
Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/metabolismo , Temperatura Baixa , Resposta ao Choque Frio , Glicólise , Desenvolvimento Muscular , Aclimatação , Tecido Adiposo Branco/citologia , Tecido Adiposo Branco/metabolismo , Animais , Diferenciação Celular , Sobrevivência Celular , Metabolismo Energético , Fator de Transcrição de Proteínas de Ligação GA/metabolismo , Homeostase , Masculino , Camundongos , Proteína MyoD/metabolismo , Mioblastos/citologia , Receptores Adrenérgicos beta/metabolismoRESUMO
The physiologic signals that regulate beige adipogenesis remain incompletely understood, especially those that limit browning and prevent overexpenditure of energy. In this study, the TNF family member cytokine lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells (LIGHT), also known as TNF super family protein 14 (TNFSF14), can inhibit adipose precursor differentiation into beige adipocytes. In acute cold stress, LIGHT deficiency in mice accelerated browning in the subcutaneous white adipose tissue (scWAT). Further experiments showed that LIGHT interacting with lymphotoxin-ß receptor (LTßR) on adipose precursors blocked beige fat biogenesis. LTßR signals attenuated the JNK pathway, which contributed to their antibeiging effect. Blocking JNK activation using a small molecular inhibitor prevented cold-induced scWAT beiging. Furthermore, LIGHT/LTßR signals acted as an attenuator of white adipogenesis. LIGHT deficiency in mice promoted obesity during high-fat diet feeding. These findings identify the LIGHT axis as a regulator of adipose tissue homeostasis and suggest that LIGHT signaling functions as a mechanism to divert energy in favor of immune activation.-Kou, Y., Liu, Q., Liu, W., Sun, H., Liang, M., Kong, F., Zhang, B., Wei, Y., Liu, Z., Wang, Y. LIGHT/TNFSF14 signaling attenuates beige fat biogenesis.
Assuntos
Adipogenia , Tecido Adiposo Bege/metabolismo , Transdução de Sinais , Membro 14 da Superfamília de Ligantes de Fatores de Necrose Tumoral/metabolismo , Células 3T3-L1 , Adipócitos Bege , Tecido Adiposo Bege/citologia , Animais , Receptor beta de Linfotoxina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/metabolismo , Membro 14 da Superfamília de Ligantes de Fatores de Necrose Tumoral/genéticaRESUMO
BACKGROUND/AIMS: Brown and beige adipocytes are widely recognized as potential therapeutic targets to treat obesity and related metabolic disorders, and the recruitment of brown and beige adipocytes is an essential aspect that requires attention. Although many methods of activating brown adipocytes or generating beige adipocytes have been reported, the limited number and sources are the biggest challenges. The number of white adipocytes is much greater than the number of brown adipocytes, both in human adults and fetuses. Unfortunately, human adult white adipose tissue-derived stem cell (aWAsc) has little beige adipogenic potential. However, the characteristics and beige adipogenic potential of human embryo-derived white adipose stem cells (eWAsc) still need to be investigated. METHODS: To analyze the characteristics and functionality of eWAsc, we analyzed the markers of adipose precursor cells by flow cytometry. Then, differentiation and browning/beiging were induced, and the identifying markers were analyzed by real-time PCR and immunoblot. In addition, more in-depth exploration was performed using RNA-SEQ on eWAsc and aWAsc. RESULTS: eWAsc was isolated from human embryonic white adipose tissue, and aWAsc was isolated from adult white adipose tissue by collagenase treatment. eWAsc has extreme advantages in adipogenesis capacity and browning/beiging ability in comparison to aWAsc, indicating that eWAsc may possess some special regulatory factors to promote the generation of functional brown/beige adipocytes. Greater exploration was enabled by RNA-SEQ, revealing a large number of differences at the transcriptional levels, including 1263 differentially expressed genes, 657 down- and 605 upregulated, in eWAsc compared to aWAsc. Pathway analysis revealed enrichment in cell cycle, TGF-ß signaling pathway, DNA replication, and Hippo signaling pathways. Interestingly, the expression levels of C/EBPα, FGF1 and FST gene, which are related to the maturation of adipocytes, Hippo signaling pathway and TGF-ß signaling pathway, were significantly higher in eWAsc than in aWAsc. These may be potential candidates and possible regulatory targets for recruiting beige adipocytes in human adipose tissue. CONCLUSION: Overall, we have demonstrated the molecular characteristics and excellent beige adipogenic potential of eWAsc, providing a new reference for studying human adipocytes.
Assuntos
Adipogenia , Tecido Adiposo Bege/citologia , Tecido Adiposo Branco/citologia , Embrião de Mamíferos/citologia , Células-Tronco/citologia , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/citologia , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/metabolismo , Células Cultivadas , Embrião de Mamíferos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Células-Tronco/metabolismoRESUMO
OBJECTIVE: The anti-obesity actions of growth hormone (GH) led us to investigate if GH signaling is able to regulate beige/brite fat development of white adipose tissue (WAT). METHODS: We studied WAT in GHR-391 mice engineered to be unable to activate STAT5 in response to GH, in mice with adipose specific deletion of GHR, in GHR-/- mice and in bGH transgenic mice. QPCR, immunoblots and immunohistochemistry were used to characterize WAT. The in vivo effects of ß-3 adrenergic activation with CL-316,243 and that of FGF21 infusion were also studied. RESULTS: GHR-391 mice had lower surface temperature than WT, with deficiency in ß-oxidation and beiging transcripts including Ucp1. Oxidative phosphorylation complex subunit proteins were decreased dramatically in GHR-391 inguinal white adipose tissue (iWAT), but increased in bGH iWAT, as were proteins for beige/brown markers. In accord with its lack of ß-3 adrenergic receptors, iWAT of GHR-391 mice did not beige in response to administration of the ß-3 specific agonist CL-316,243 in contrast to WT mice. GHR-391 mice are deficient in FGF21, but unlike WT, infusion of the purified protein was without effect on extent of beiging. Finally, fat-specific deletion of the GHR replicated the loss of beiging associated transcripts. CONCLUSION: In addition to promoting lipolysis, our study suggests that GH is able to promote formation of beige adipose tissue through activation of STAT5 and induction of Adrb3. This sensitizes WAT to adrenergic input, and may contribute to the anti-obesity actions of GH.
Assuntos
Tecido Adiposo Bege/citologia , Tecido Adiposo Branco/citologia , Proteínas de Transporte/fisiologia , Hormônio do Crescimento/metabolismo , Fator de Transcrição STAT5/metabolismo , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Branco/metabolismo , Animais , Bovinos , Fatores de Crescimento de Fibroblastos/metabolismo , Hormônio do Crescimento/genética , Camundongos , Camundongos Knockout , Receptores Adrenérgicos/metabolismo , Fator de Transcrição STAT5/genética , Transdução de SinaisRESUMO
Caloric restriction (CR) stimulates development of functional beige fat and extends healthy lifespan. Here we show that compositional and functional changes in the gut microbiota contribute to a number of CR-induced metabolic improvements and promote fat browning. Mechanistically, these effects are linked to a lower expression of the key bacterial enzymes necessary for the lipid A biosynthesis, a critical lipopolysaccharide (LPS) building component. The decreased LPS dictates the tone of the innate immune response during CR, leading to increased eosinophil infiltration and anti-inflammatory macrophage polarization in fat of the CR animals. Genetic and pharmacological suppression of the LPS-TLR4 pathway or transplantation with Tlr4-/- bone-marrow-derived hematopoietic cells increases beige fat development and ameliorates diet-induced fatty liver, while Tlr4-/- or microbiota-depleted mice are resistant to further CR-stimulated metabolic alterations. These data reveal signals critical for our understanding of the microbiota-fat signaling axis during CR and provide potential new anti-obesity therapeutics.
Assuntos
Tecido Adiposo Bege/metabolismo , Proteínas de Bactérias/metabolismo , Restrição Calórica , Fígado Gorduroso/metabolismo , Microbioma Gastrointestinal , Trato Gastrointestinal , Lipídeo A/metabolismo , Tecido Adiposo Bege/citologia , Animais , Eosinófilos/imunologia , Trato Gastrointestinal/imunologia , Trato Gastrointestinal/microbiologia , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Receptor 4 Toll-Like/metabolismoRESUMO
OBJECTIVE: Beige/brite adipose tissue displays morphological characteristics and beneficial metabolic traits of brown adipose tissue. Previously, we showed that TGF-ß signaling regulates the browning of white adipose tissue. Here, we inquired whether TGF-ß signals regulated presumptive beige progenitors in white fat and investigated the TGF-ß regulated mechanisms involved in beige adipogenesis. METHODS: We deleted TGF-ß receptor 1 (TßRI) in adipose tissue (TßRIAdKO mice) and, using flow-cytometry based assays, identified and isolated presumptive beige progenitors located in the stromal vascular cells of white fat. These cells were molecularly characterized to examine beige/brown marker expression and to investigate TGF-ß dependent mechanisms. Further, the cells were transplanted into athymic nude mice to examine their adipogenesis potential. RESULTS: Deletion of TßRI promotes beige adipogenesis while reducing the detrimental effects of high fat diet feeding. Interaction of TGF-ß signaling with the prostaglandin pathway regulated the appearance of beige adipocytes in white fat. Using flow cytometry techniques and stromal vascular fraction from white fat, we isolated presumptive beige stem/progenitor cells (iBSCs). Upon genetic or pharmacologic inhibition of TGF-ß signaling, these cells express high levels of predominantly beige markers. Transplantation of TßRI-deficient stromal vascular cells or iBSCs into athymic nude mice followed by high fat diet feeding and stimulation of ß-adrenergic signaling via CL316,243 injection or cold exposure promoted robust beige adipogenesis in vivo. CONCLUSIONS: TßRI signals target the prostaglandin network to regulate presumptive beige progenitors in white fat capable of developing into beige adipocytes with functional attributes. Controlled inhibition of TßRI signaling and concomitant PGE2 stimulation has the potential to promote beige adipogenesis and improve metabolism.
Assuntos
Adipócitos Marrons/citologia , Adipócitos Brancos/citologia , Receptor do Fator de Crescimento Transformador beta Tipo I/metabolismo , Células-Tronco/citologia , Adipócitos Bege/citologia , Adipócitos Bege/metabolismo , Adipócitos Marrons/metabolismo , Adipócitos Brancos/metabolismo , Adipogenia , Tecido Adiposo Bege/citologia , Tecido Adiposo Bege/metabolismo , Tecido Adiposo Marrom/citologia , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/citologia , Tecido Adiposo Branco/metabolismo , Animais , Diferenciação Celular/fisiologia , Dieta Hiperlipídica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/metabolismo , Transdução de Sinais , Células-Tronco/metabolismo , Fator de Crescimento Transformador beta1/metabolismoRESUMO
OBJECTIVE: The vascular system is central to sustaining tissue survival and homeostasis. Blood vessels are densely present in adipose tissues and exert essential roles in their metabolism. However, conventional immunohistochemistry methods have intrinsic limitations in examining the 3D vascular network in adipose tissues as well as other organs in general. METHODS: We established a 3D volume fluorescence-imaging technique to visualize the vasculatures in mouse adipose tissues by combining the optimized steps of whole-mount immunolabeling, tissue optical clearing, and lightsheet volume fluorescence-imaging. To demonstrate the strength of this novel imaging procedure, we comprehensively assessed the intra-adipose vasculatures under obese conditions or in response to a cold challenge. RESULTS: We show the entirety of the vascular network in mouse adipose tissues on the whole-tissue level at a single-capillary resolution for the first time in the field. We accurately quantify the pathological changes of vasculatures in adipose tissues in wild-type or obese mice (ob/ob, db/db, or diet-induced obesity). In addition, we identify significant and reversible changes of the intra-adipose vasculatures in the mice subjected to cold challenge (i.e., 4°). Furthermore, we demonstrate that the cold-induced vascular plasticity depends on the sympathetic-derived catecholamine signal and is involved in the beiging process of white adipose tissues. CONCLUSIONS: We report a 3D volume fluorescence-imaging procedure that is compatible with many areas of vascular research and is poised to serve the field in future investigations of the vascular system in adipose tissues or other research scenarios.