Assessment of Bioenergetics in BAT Mitochondria.

High-resolution respirometry is commonly used to quantify mitochondrial respiratory rates. In the respirometry chamber, a change in oxygen concentration is measured by a polarographic electrode to derive the rate of oxygen consumption (JO2). Here, we describe our adapted protocol to bioenergetically phenotype mitochondria from mouse brown adipose tissue (BAT). Given the presence of uncoupling protein 1 (UCP1), mitochondria from BAT provide unique challenges and opportunities in applying high-resolution respirometry to understand energy transduction through oxidative phosphorylation (OXPHOS).

Assessment of Brown and Beige Adipose Tissue Activation in Mice Using PET/CT Imaging.

In response to cold induction, brown adipose tissues (BAT) and emerged brown-like adipocytes (beige adipocytes) in subcutaneous white adipose tissues (WAT browning/beiging) are activated. Thermogenesis is increased during glucose and fatty acid uptake and metabolism in adult humans and mice. This activation of BAT or WAT beiging to generate heat helps to counteract diet-induced obesity. This protocol applies the glucose analog radiotracer 18F-fluorodeoxyglucose (FDG), coupled with positron emission tomography and computed tomography (PET/CT) scanning to evaluate cold-induced thermogenesis in the active BAT (interscapular region) and browned/beiged WAT (subcutaneous adipose region) in mice. The PET/CT scanning technique not only can quantify cold-induced glucose uptake in well-known BAT and beige-fat depots but also helps to visualize the anatomical location of novel uncharacterized mouse BAT and beige fat where cold-induced glucose uptake is high. Histological analysis is further employed to validate signals of delineated anatomical regions in PET/CT images as bona fide mouse BAT or beiged WAT fat depots.

Cold acclimation and pioglitazone combined increase thermogenic capacity of brown and white adipose tissues but this does not translate into higher energy expenditure in mice.

Cold acclimation and pharmacological peroxisome proliferator-activated receptor γ (PPARγ) activation have each earlier been shown to recruit brown adipose tissue (BAT) and beige adipocytes thermogenic machinery, enhancing uncoupling protein 1 (UCP1)-mediated thermogenic capacity. We here investigated whether cold acclimation and PPARγ agonism combined have additive effects in inducing brown and beige adipocytes UCP1 content and whether this translates into a higher thermogenic capacity and energy expenditure. C57BL/6J mice treated or not with pioglitazone (30 mg/kg/day) were maintained at 21°C or exposed to cold (7°C) for 15 days and evaluated for thermogenic capacity, energy expenditure and interscapular BAT (iBAT) and inguinal white adipose tissue (iWAT) mass, morphology, UCP1 content and gene expression, glucose uptake and oxygen consumption. Cold acclimation and PPARγ agonism combined synergistically increased iBAT and iWAT total UCP1 content and mRNA levels of the thermogenesis-related proteins PGC1a, CIDEA, FABP4, GYK, PPARa, LPL, GLUTs (GLUT1 in iBAT and GLUT4 in iWAT), and ATG when compared to cold and pioglitazone individually. This translated into a stronger increase in body temperature in response to the ß3-adrenergic agonist CL316,243 and iBAT and iWAT respiration induced by succinate and pyruvate in comparison to that seen in either cold-acclimated or pioglitazone-treated mice. However, basal energy expenditure, BAT glucose uptake and glucose tolerance were not increased above that seen in cold-acclimated untreated mice. In conclusion, cold acclimation and PPARγ agonism combined induced a robust increase in brown and beige adipocytes UCP1 content and thermogenic capacity, much higher than each treatment individually. However, our findings enforce the concept that increases in total UCP1 do not innately lead to higher energy expenditure.NEW & NOTEWORTHY Cold acclimation and PPARγ agonism combined markedly increase brown and white adipose tissue total UCP1 content and mRNA levels of thermogenesis-related proteins. Higher UCP1 protein levels did not result in higher energy expenditure. The high thermogenic capacity induced by PPARγ agonism in cold-exposed animals markedly increases animals' body temperature in response to the ß3-adrenergic agonist CL316,243.

The ABA/LANCL1/2 Hormone/Receptor System Controls Adipocyte Browning and Energy Expenditure.

The abscisic acid (ABA)/LANC-like protein 1/2 (LANCL1/2) hormone/receptor system regulates glucose uptake and oxidation, mitochondrial respiration, and proton gradient dissipation in myocytes. Oral ABA increases glucose uptake and the transcription of adipocyte browning-related genes in rodent brown adipose tissue (BAT). The aim of this study was to investigate the role of the ABA/LANCL system in human white and brown adipocyte thermogenesis. Immortalized human white and brown preadipocytes, virally infected to overexpress or silence LANCL1/2, were differentiated in vitro with or without ABA, and transcriptional and metabolic targets critical for thermogenesis were explored. The overexpression of LANCL1/2 increases, and their combined silencing conversely reduces mitochondrial number, basal, and maximal respiration rates; proton gradient dissipation; and the transcription of uncoupling genes and of receptors for thyroid and adrenergic hormones, both in brown and in white adipocytes. The transcriptional enhancement of receptors for browning hormones also occurs in BAT from ABA-treated mice, lacking LANCL2 but overexpressing LANCL1. The signaling pathway downstream of the ABA/LANCL system includes AMPK, PGC-1α, Sirt1, and the transcription factor ERRα. The ABA/LANCL system controls human brown and "beige" adipocyte thermogenesis, acting upstream of a key signaling pathway regulating energy metabolism, mitochondrial function, and thermogenesis.

Brief Communication: Histological Assessment of Nonhuman Primate Brown Adipose Tissue Highlights the Importance of Sympathetic Innervation.

Objective: The objective of this study was to functionally analyze the correlation of key histological features in brown adipose tissue (BAT) with clinical metabolic traits in nonhuman primates. Methods: Axillary adipose tissue biopsies were collected from a metabolically diverse nonhuman primate cohort with clinical metabolism-related data. Expression of tyrosine hydroxylase (TH), uncoupling protein 1 (UCP1), cluster of differentiation 31 (CD31), cytochrome c oxidase subunit 4 (COX IV), beta-3 adrenergic receptor (ß3-AR), and adipose cell size were quantified by immunohistochemical analysis. Computed tomography scans were performed to assess body composition. Results: Tyrosine hydroxylase was negatively correlated with whole body fat mass as a percentage of body weight (p = 0.004) and was positively correlated with the density of UCP1 (p = 0.02), COX IV (p = 0.006), CD31 (p = 0.007), and cell density (p = 0.02) of the BAT samples. Beta-3 adrenergic receptor abundance had a weak positive correlation with COX IV (p = 0.04) in BAT but did not significantly correlate to UCP1 or TH expression in BAT. Conclusions: Our findings highlight that there is a disparity in innervation provided to BAT based on body composition, as seen with the negative association between TH, a marker for innervation, and adiposity. These findings also support the importance of innervation in the functionality of BAT, as TH abundance not only supports leaner body composition but is also positively correlated with known structural elements in BAT (UCP1, COX IV, CD31, and cell density). Based on our observations, ß3-AR abundance does not strongly drive these structural elements or TH, all of which are known to be important in the function of brown adipose tissue. In effect, while the role of other receptors, such as ß2-AR, should be reviewed in BAT function, these results support the development of safe sympathetic nervous system stimulants to activate brown adipose tissue for obesity treatment.

SIRT7 suppresses energy expenditure and thermogenesis by regulating brown adipose tissue functions in mice.

Brown adipose tissue plays a central role in the regulation of the energy balance by expending energy to produce heat. NAD+-dependent deacylase sirtuins have widely been recognized as positive regulators of brown adipose tissue thermogenesis. However, here we reveal that SIRT7, one of seven mammalian sirtuins, suppresses energy expenditure and thermogenesis by regulating brown adipose tissue functions. Whole-body and brown adipose tissue-specific Sirt7 knockout mice have higher body temperature and energy expenditure. SIRT7 deficiency increases the protein level of UCP1, a key regulator of brown adipose tissue thermogenesis. Mechanistically, we found that SIRT7 deacetylates insulin-like growth factor 2 mRNA-binding protein 2, an RNA-binding protein that inhibits the translation of Ucp1 mRNA, thereby enhancing its inhibitory action on Ucp1. Furthermore, SIRT7 attenuates the expression of batokine genes, such as fibroblast growth factor 21. In conclusion, we propose that SIRT7 serves as an energy-saving factor by suppressing brown adipose tissue functions.

A modest change in housing temperature alters whole body energy expenditure and adipocyte thermogenic capacity in mice.

Typical vivarium temperatures (20-26°C) induce facultative thermogenesis in mice, a process attributable in part to uncoupling protein-1 (UCP1). The impact of modest changes in housing temperature on whole body and adipose tissue energetics in mice remains unclear. Here, we determined the effects of transitioning mice from 24°C to 30°C on total energy expenditure and adipose tissue protein signatures. C57BL/6J mice were housed at 24°C for 2 wk and then either remained at 24°C (n = 16/group, 8M/8F) or were transitioned to 30°C (n = 16/group, 8M/8F) for 4 wk. Total energy expenditure and its components were determined by indirect calorimetry. Interscapular brown adipose tissue (iBAT) and inguinal white adipose tissue (iWAT) proteins were quantified by Western blot and quantitative proteomics. Transitioning from 24°C to 30°C reduced total energy expenditure in both male (-25%) and female (-16%) mice, which was attributable to lower basal energy expenditure in males (-36%) and females (-40%). Total iBAT UCP1 protein content was 50% lower at 30°C compared with 24°C, whereas iWAT UCP1 protein content was similar between conditions. iBAT UCP1 protein content remained 20-fold greater than iWAT at 30°C. In iBAT and iWAT, 183 and 41 proteins were differentially expressed between 24°C and 30°C, respectively. iWAT proteins (257) differentially expressed between sexes at 30°C were not differentially expressed at 24°C. Thus, 30°C housing lowers total energy expenditure of mice when compared with an ambient temperature (24°C) that falls within the National Research Council's guidelines for housing laboratory mice. Lower iBAT UCP1 content accompanied chronic housing at 30°C. Furthermore, housing temperature influences sexual dimorphism in the iWAT proteome. These data have implications regarding the optimization of preclinical models of human disease.NEW & NOTEWORTHY Housing mice at 30°C reduced the basal and total energy expenditure compared with 24°C, which was accompanied by a reduction in brown adipose tissue UCP1 content. Proteomic profiling demonstrated the brown adipose tissue and white adipose tissue proteomes were largely influenced by housing temperature and sex, respectively. Therefore, 30°C housing revealed sexual dimorphism in the white adipose tissue proteome that was largely absent in animals housed at 24°C.

Suppression of obesity by melatonin through increasing energy expenditure and accelerating lipolysis in mice fed a high-fat diet.

BACKGROUNDS/OBJECTIVES: Melatonin promotes brown adipose tissue (BAT) activity, leading to body mass reduction and energy expenditure. However, the mechanisms governing these beneficial effects are not well-established. This study aimed to assess the effects of (1) melatonin on BAT and energy metabolism, and (2) fibroblast growth factor 21 (FGF21) in BAT-mediated thermogenesis. METHODS: Male C57BL/6 J mice received a high-fat diet (HFD) or normal chow, accompanied by intraperitoneal injection of 20 mg/kg melatonin for 12 weeks. FGF21-/- mice consumed an HFD with or without melatonin for 8 weeks. RESULTS: Melatonin attenuated weight gain, insulin resistance, adipocyte hypertrophy, inflammation, and hepatic steatosis induced by the HFD and increased energy expenditure. Furthermore, melatonin improved cold tolerance by increasing BAT uncoupling protein 1 (UCP1) expression and producing heat. Notably, melatonin resulted in a shift in energy metabolism favouring the utilization of fat, and it increased FGF21 in circulating and metabolic tissues and skeletal muscle phosphorylation of AMP-activated protein kinase. However, melatonin did not protect against obesity, insulin resistance, and energy expenditure in HFD-fed FGF21-/- mice. CONCLUSIONS: Melatonin suppressed obesity and insulin resistance resulting from the HFD by enhancing BAT activity and energy expenditure, and these effects were dependent on FGF21.

Apoptotic brown adipocytes enhance energy expenditure via extracellular inosine.

Brown adipose tissue (BAT) dissipates energy1,2 and promotes cardiometabolic health3. Loss of BAT during obesity and ageing is a principal hurdle for BAT-centred obesity therapies, but not much is known about BAT apoptosis. Here, untargeted metabolomics demonstrated that apoptotic brown adipocytes release a specific pattern of metabolites with purine metabolites being highly enriched. This apoptotic secretome enhances expression of the thermogenic programme in healthy adipocytes. This effect is mediated by the purine inosine that stimulates energy expenditure in brown adipocytes by the cyclic adenosine monophosphate-protein kinase A signalling pathway. Treatment of mice with inosine increased BAT-dependent energy expenditure and induced 'browning' of white adipose tissue. Mechanistically, the equilibrative nucleoside transporter 1 (ENT1, SLC29A1) regulates inosine levels in BAT: ENT1-deficiency increases extracellular inosine levels and consequently enhances thermogenic adipocyte differentiation. In mice, pharmacological inhibition of ENT1 as well as global and adipose-specific ablation enhanced BAT activity and counteracted diet-induced obesity, respectively. In human brown adipocytes, knockdown or blockade of ENT1 increased extracellular inosine, which enhanced thermogenic capacity. Conversely, high ENT1 levels correlated with lower expression of the thermogenic marker UCP1 in human adipose tissues. Finally, the Ile216Thr loss of function mutation in human ENT1 was associated with significantly lower body mass index and 59% lower odds of obesity for individuals carrying the Thr variant. Our data identify inosine as a metabolite released during apoptosis with a 'replace me' signalling function that regulates thermogenic fat and counteracts obesity.

Combined Phyllostachys pubescens and Scutellaria baicalensis Prevent High-Fat Diet-Induced Obesity via Upregulating Thermogenesis and Energy Expenditure by UCP1 in Male C57BL/6J Mice.

This study examined the anti-obesity effects of a Phyllostachys pubescens (leaf) and Scutellaria baicalensis root mixture (BS21), and its underlying mechanisms of action, in high-fat diet (HFD)-induced obese mice. Mice were fed a HFD with BS21 (100, 200, or 400 mg/kg) for 9 weeks. BS21 reduced body weight, white adipose tissue (WAT) and liver weights, liver lipid accumulation, and adipocyte size. Additionally, BS21 reduced serum concentrations of non-esterified fatty acid, triglyceride, glucose, lactate dehydrogenase, low-density lipoprotein cholesterol, total cholesterol, leptin, and insulin growth factor 1, but elevated the adiponectin concentrations. Furthermore, BS21 suppressed the mRNA levels of lipogenesis-related proteins, such as peroxisome proliferator-activated receptor (PPAR) γ, SREBP-1c, C/EBP-α, fatty acid synthase, and leptin, but increased the mRNA gene expression of lipolysis-related proteins, such as PPAR-α, uncoupling protein (UCP) 2, adiponectin, and CPT1b, in WAT. In addition, BS21 increased the cold-stimulated adaptive thermogenesis and UCP1 protein expression with AMPK activation in adipose tissue. Furthermore, BS21 increased the WAT and mRNA expression of energy metabolism-related proteins SIRT1, PGC-1α, and FNDC5/irisin in the quadriceps femoris muscle. These results suggest that BS21 exerts anti-obesity and antihyperlipidemic activities in HFD-induced obese mice by increasing the thermogenesis and energy expenditure, and regulating lipid metabolism. Therefore, BS21 could be useful for preventing and treating obesity and its related metabolic diseases.

Cysteine 253 of UCP1 regulates energy expenditure and sex-dependent adipose tissue inflammation.

Uncoupling protein 1 (UCP1) is a major regulator of brown and beige adipocyte energy expenditure and metabolic homeostasis. However, the widely employed UCP1 loss-of-function model has recently been shown to have a severe deficiency in the entire electron transport chain of thermogenic fat. As such, the role of UCP1 in metabolic regulation in vivo remains unclear. We recently identified cysteine-253 as a regulatory site on UCP1 that elevates protein activity upon covalent modification. Here, we examine the physiological importance of this site through the generation of a UCP1 cysteine-253-null (UCP1 C253A) mouse, a precise genetic model for selective disruption of UCP1 in vivo. UCP1 C253A mice exhibit significantly compromised thermogenic responses in both males and females but display no measurable effect on fat accumulation in an obesogenic environment. Unexpectedly, we find that a lack of C253 results in adipose tissue redox stress, which drives substantial immune cell infiltration and systemic inflammatory pathology in adipose tissues and liver of male, but not female, mice. Elevation of systemic estrogen reverses this male-specific pathology, providing a basis for protection from inflammation due to loss of UCP1 C253 in females. Together, our results establish the UCP1 C253 activation site as a regulator of acute thermogenesis and sex-dependent tissue inflammation.

A pyrexic effect of FGF21 independent of energy expenditure and UCP1.

OBJECTIVE: Administration of FGF21 to mice reduces body weight and increases body temperature. The increase in body temperature is generally interpreted as hyperthermia, i.e. a condition secondary to the increase in energy expenditure (heat production). Here, we examine an alternative hypothesis: that FGF21 has a direct pyrexic effect, i.e. FGF21 increases body temperature independently of any effect on energy expenditure. METHODS: We studied the effects of FGF21 treatment on body temperature and energy expenditure in high-fat-diet-fed and chow-fed mice exposed acutely to various ambient temperatures, in high-fat diet-fed mice housed at 30 °C (i.e. at thermoneutrality), and in mice lacking uncoupling protein 1 (UCP1). RESULTS: In every model studied, FGF21 increased body temperature, but energy expenditure was increased only in some models. The effect of FGF21 on body temperature was more (not less, as expected in hyperthermia) pronounced at lower ambient temperatures. Effects on body temperature and energy expenditure were temporally distinct (daytime versus nighttime). FGF21 enhanced UCP1 protein content in brown adipose tissue (BAT); there was no measurable UCP1 protein in inguinal brite/beige adipose tissue. FGF21 increased energy expenditure through adrenergic stimulation of BAT. In mice lacking UCP1, FGF21 did not increase energy expenditure but increased body temperature by reducing heat loss, e.g. a reduced tail surface temperature. CONCLUSION: The effect of FGF21 on body temperature is independent of UCP1 and can be achieved in the absence of any change in energy expenditure. Since elevated body temperature is a primary effect of FGF21 and can be achieved without increasing energy expenditure, only limited body weight-lowering effects of FGF21 may be expected.

Pancreastatin mediated regulation of UCP-1 and energy expenditure in high fructose fed perimenopausal rats.

AIMS: Pancreastatin (PST) is a crucial bioactive peptide derived from chromogranin A (CHGA) proprotein that exhibits an anti-insulin effect on adipocytes. Herein, we investigated the effects of PST on brown adipose tissues (BAT) and white adipose tissue (WAT) in connection with uncoupling protein-1 (UCP-1) regulated energy expenditure in high fructose diet (HFrD) fed and vinylcyclohexenediepoxide (VCD) induced perimenopausal rats. MATERIAL AND METHODS: We administered VCD in rats for 17 consecutive days and fed HFrd for 12 weeks. After 12 weeks estradiol and progesterone levels were detected. Furthermore, detection of glucose tolerance, insulin sensitivity, and body composition revealed impaired glucose homeostasis and enhanced PST levels. Effects of enhanced PST on UCP-1 level in BAT and WAT of perimenopausal rats were further investigated. KEY FINDINGS: Reduced serum estradiol, progesterone, and attenuated insulin response confirmed perimenopausal model development. Furthermore, enhanced PST serum level and its increased expression in BAT and WAT downregulated the UCP-1 expression. Subsequently, impaired ATP level, NADP/NADPH ratio, citrate synthase activity, enhanced mitochondrial reactive oxygen species (ROS) generation and perturbed mitochondrial membrane potential, further exacerbated mitochondrial dysfunction, cellular ROS production, and promoted apoptosis. Interestingly, PST inhibition by PST inhibitor peptide-8 (PSTi8) displayed a favorable impact on UCP-1 and energy expenditure. SIGNIFICANCE: The aforementioned outcomes indicated the substantial role of PST in altering the UCP-1 expression and associated energy homeostasis. Hence our results corroborate novel avenues to unravel the quest deciphering PST's role in energy homeostasis and its association with perimenopause.

Phytohemagglutinin ameliorates HFD-induced obesity by increasing energy expenditure.

Despite all modern advances in medicine, there are few reports of effective and safe drugs to treat obesity. Our objective was to screen anti-obesity natural compounds, and to verify whether they can reduce the body weight gain and investigate their molecular mechanisms. By using drug-screening methods, Phytohemagglutinin (PHA) was found to be the most anti-obesity candidate natural compound. Six-week-old C57BL/6J mice were fed with a high-fat diet (HFD) and intraperitoneally injected with 0.25 mg/kg PHA everyday for 8 weeks. The body weight, glucose homeostasis, oxygen consumption and physical activity were assessed. We also measured the heat intensity, body temperature and the gene expression of key regulators of energy expenditure. Prevention study results showed PHA treatment not only reduced the body weight gain but also maintained glucose homeostasis in HFD-fed mice. Further study indicated energy expenditure and uncoupling protein 1 (UCP-1) expression of brown adipose tissue (BAT) and white adipose tissue (WAT) in HFD-fed mice were significantly improved by PHA. In the therapeutic study, a similar effect was observed. PHA inhibited lipid droplet formation and upregulated mitochondrial-related gene expression during adipogenesis in vitro. UCP-1 KO mice displayed no differences in body weight, glucose homeostasis and core body temperature between PHA and control groups. Our results suggest that PHA prevent and treat obesity by increasing energy expenditure through upregulation of BAT thermogenesis.

Pseudo-Starvation Driven Energy Expenditure Negatively Affects Ovarian Follicle Development.

In the present investigation, we examined whether a change in whole body energy fluxes could affect ovarian follicular development, employing mice ectopically expressing uncoupling protein 1 in skeletal muscle (UCP1-TG). Female UCP1-TG and wild-type (WT) mice were dissected at the age of 12 weeks. Energy intake and expenditure, activity, body weight and length, and body composition were measured. Plasma insulin, glucose, leptin, plasma fibroblast growth factor 21 (FGF21) and plasma insulin-like growth factor 1 (IGF1) levels were analyzed and ovarian follicle and corpus luteum numbers were counted. IGF1 signaling was analyzed by immunohistochemical staining for the activation of insulin receptor substrate 1/2 (IRS1/2) and AKT. UCP1-TG female mice had increased energy expenditure, reduced body size, maintained adiposity, and decreased IGF1 concentrations compared to their WT littermates, while preantral and antral follicle numbers were reduced by 40% and 60%, respectively. Corpora lutea were absent in 40% of the ovaries of UCP1-TG mice. Phospho-IRS1, phospho-AKT -Ser473 and -Thr308 immunostaining was present in the granulosa cells of antral follicles in WT ovaries, but faint to absent in the antral follicles of UCP1-TG mice. In conclusion, the reduction in circulating IGF1 levels due to the ectopic expression of UCP1 is associated with reduced immunostaining of the IRS1-PI3/AKT pathway, which may negatively affect ovarian follicle development and ovulation.

Withaferin A exerts an anti-obesity effect by increasing energy expenditure through thermogenic gene expression in high-fat diet-fed obese mice.

BACKGROUND: The enhancement of energy expenditure has attracted attention as a therapeutic target for the management of body weight. Withaferin A (WFA), a major constituent of Withania somnifera extract, has been reported to possess anti-obesity properties, however the underlying mechanism remains unknown. PURPOSE: To investigate whether WFA exerts anti-obesity effects via increased energy expenditure, and if so, to characterize the underlying pathway. METHODS: C57BL/6 J mice were fed a high-fat diet (HFD) for 10 weeks, and WFA was orally administered for 7 days. The oxygen consumption rate of mice was measured at 9 weeks using an OxyletPro™ system. Hematoxylin and eosin (H&E), immunohistochemistry, immunoblotting, and real-time PCR methods were used. RESULTS: Treatment with WFA ameliorated HFD-induced obesity by increasing energy expenditure by improving of mitochondrial activity in brown adipose tissue (BAT) and promotion of subcutaneous white adipose tissue (scWAT) browning via increasing uncoupling protein 1 levels. WFA administration also significantly increased AMP-activated protein kinase (AMPK) phosphorylation in the BAT of obese mice. Additionally, WFA activated mitogen-activated protein kinase (MAPK) signaling, including p38/extracellular signal-regulated kinase MAPK, in both BAT and scWAT. CONCLUSION: WFA enhances energy expenditure and ameliorates obesity via the induction of AMPK and activating p38/extracellular signal-regulated kinase MAPK, which triggers mitochondrial biogenesis and browning-related gene expression.

Ectopic brown adipose tissue formation within skeletal muscle after brown adipose progenitor cell transplant augments energy expenditure.

Brown adipose tissue (BAT) thermogenesis increases energy expenditure (EE). Expanding the volume of active BAT via transplantation holds promise as a therapeutic strategy for morbid obesity and diabetes. Brown adipose progenitor cells (BAPCs) can be isolated and expanded to generate autologous brown adipocyte implants. However, the transplantation of brown adipocytes is currently impeded by poor efficiency of BAT tissue formation in vivo and undesirably short engraftment time. In this study, we demonstrated that transplanting BAPCs into limb skeletal muscles consistently led to the ectopic formation of uncoupling protein 1 (UCP1)+pos adipose tissue with long-term engraftment (>4 mo). Combining VEGF with the BAPC transplant further improved BAT formation in muscle. Ectopic engraftment of BAPC-derived BAT in skeletal muscle augmented the EE of recipient mice. Although UCP1 expression declined in long-term BAT grafts, this deterioration can be reversed by swimming exercise because of sympathetic activation. This study suggests that intramuscular transplantation of BAPCs represents a promising approach to deriving functional BAT engraftment, which may be applied to therapeutic BAT transplantation and tissue engineering.-Liu, Y., Fu, W., Seese, K., Yin, A., Yin, H. Ectopic brown adipose tissue formation within skeletal muscle after brown adipose progenitor cell transplant augments energy expenditure.

The Suv420h histone methyltransferases regulate PPAR-γ and energy expenditure in response to environmental stimuli.

Obesity and its associated metabolic abnormalities have become a global emergency with considerable morbidity and mortality. Epidemiologic and animal model data suggest an epigenetic contribution to obesity. Nevertheless, the cellular and molecular mechanisms through which epigenetics contributes to the development of obesity remain to be elucidated. Suv420h1 and Suv420h2 are histone methyltransferases responsible for chromatin compaction and gene repression. Through in vivo, ex vivo, and in vitro studies, we found that Suv420h1 and Suv420h2 respond to environmental stimuli and regulate metabolism by down-regulating peroxisome proliferator-activated receptor gamma (PPAR-γ), a master transcriptional regulator of lipid storage and glucose metabolism. Accordingly, mice lacking Suv420h proteins activate PPAR-γ target genes in brown adipose tissue to increase mitochondria respiration, improve glucose tolerance, and reduce adipose tissue to fight obesity. We conclude that Suv420h proteins are key epigenetic regulators of PPAR-γ and the pathways controlling metabolism and weight balance in response to environmental stimuli.

Fish Oil Protects Wild Type and Uncoupling Protein 1-Deficient Mice from Obesity and Glucose Intolerance by Increasing Energy Expenditure.

SCOPE: The mechanisms and involvement of uncoupling protein 1 (UCP1) in the protection from obesity and insulin resistance induced by intake of a high-fat diet rich in omega-3 (n-3) fatty acids are investigated. METHODS AND RESULTS: C57BL/6J mice are fed either a low-fat (control group) or one of two isocaloric high-fat diets containing either lard (HFD) or fish oil (HFN3) as fat source and evaluated for body weight, adiposity, energy expenditure, glucose homeostasis, and inguinal white and interscapular brown adipose tissue (iWAT and iBAT, respectively) gene expression, lipidome, and mitochondrial bioenergetics. HFN3 intake protected from obesity, glucose and insulin intolerances, and hyperinsulinemia. This is associated with increased energy expenditure, iWAT UCP1 expression, and incorporation of n-3 eicosapentaenoic and docosahexaenoic fatty acids in iWAT and iBAT triacylglycerol. Importantly, HFN3 is equally effective in reducing body weight gain, adiposity, and glucose intolerance and increasing energy expenditure in wild-type and UCP1-deficient mice without recruiting other thermogenic processes in iWAT and iBAT, such as mitochondrial uncoupling and SERCA-mediated calcium and creatine-driven substrate cyclings. CONCLUSION: Intake of a high-fat diet rich in omega-3 fatty acids protects both wild-type and UCP1-deficient mice from obesity and insulin resistance by increasing energy expenditure through unknown mechanisms.

Asthma alleviates obesity in males through regulating metabolism and energy expenditure.

Many epidemiological studies suggested a correlation between obesity and asthma. However, little is known about the molecular details explaining this correlation. Here, we show that asthma decreased body weight of asthmatic male mice fed with high fat diet via increasing energy expenditure and insulin sensitivity. The increase of energy expenditure was mainly due to upregulation of pAMPK and Sirt1. The activation of AMPK/Sirt1/PGC1α signaling promoted the expression of the thermogenic genes like ucp1, PRDM16, cidea, Elovl3, PPARα, which occurred in brown adipocyte tissue and subcutaneous white adipose tissue. Besides, by activating IL33/ILC2/AAMac pathway in subcutaneous white adipose tissue, asthma promoted subcutaneous white adipose tissue into beige fat. In addition, insulin sensitivity was improved in the asthmatic male mice by decreasing the expression of G6Pase in the liver, which was recapitulated in HepG2. In human, we found that Body Mass Index (BMI) and waist circumference were significantly lower in males suffering asthma compared with the control in the National Health and Nutrition Examination Survey (NHANES) cohort. These data together suggest asthma in males decreases obesity by improving the metabolism function of brown and subcutaneous adipose tissue, and decreasing insulin resistant in the liver.