Genes In Brown Adipose Tissue Research Articles

Renal sinus adipose tissue: exploratory study of metabolic features and transcriptome compared with omental and subcutaneous adipose tissue.

The objective was to study metabolic characteristics and transcriptome of renal sinus adipose tissue (RSAT) located around renal arteries and veins. Adipose tissue biopsies from RSAT, omental (OAT), and subcutaneous (SAT) depots were obtained from healthy kidney donors (20 female, 20 male). Adipocyte glucose uptake rate and cell size were measured, and gene expression analyses using transcriptomics were performed. RSAT adipocytes were significantly smaller, with a higher basal glucose uptake rate, than adipocytes from SAT and OAT. Transcriptomic analyses revealed 29 differentially expressed genes between RSAT and OAT (RSAT: 23 lower, 6 higher) and 1214 differentially expressed genes between RSAT and SAT (RSAT: 859 lower, 355 higher). RSAT demonstrated molecular resemblance to OAT, both exhibiting lower metabolic gene expression and higher expression of immune-related pathways, including IL-17, TNFα, and NF-κB signaling than SAT. Weighted gene coexpression network analysis associated RSAT with immune response and nucleic acid transport processes. Despite its location near the renal hilum, RSAT closely resembled OAT and there was a lack of expression in the classical brown adipose tissue genes. Gene enrichment analyses suggest an inflammatory environment in RSAT compared with SAT and, to some extent, OAT. The findings suggest specific RSAT functions that could impact renal function and, possibly, the development of renal and cardiometabolic disorders.

Topical menthol, a pharmacological cold mimic, induces cold sensitivity, adaptive thermogenesis and brown adipose tissue activation in mice.

Brown adipose tissue (BAT) thermogenesis has profound energy-expanding potential, which makes it an attractive target tissue to combat ever-increasing obesity and its other associated metabolic complications. Although it is fairly accepted that cold is a potent inducer of BAT activation and function, there are limited studies on the mechanisms of pharmacological cold-mimicking agents, such as the TRPM8 agonist, menthol, on BAT thermogenesis and activation. Herein, we sought to determine the effect of topical application of menthol (10% w/v [4 g/kg] cream formulation/day for 15 days) on temperature sensitivity behaviour (thermal gradient assay, nesting behaviour), adaptive thermogenesis (infrared thermography, core body temperature), BAT sympathetic innervation (tyrosine hydroxylase immunohistochemistry) and activation (18F-FDG PET-CT analysis, Uncoupling Protein 1 immunohistochemistry and BAT gene expression), whole-body energy expenditure (indirect calorimetry) and other metabolic variables in male C57BL/6N mice. We show that male C57BL/6N mice: (a) develop a warm-seeking and cold-avoiding thermal preference phenotype; (b) display increased locomotor activity and adaptive thermogenesis; (c) show augmented sympathetic innervation in BAT and its activation; (d) exhibit enhanced gluconeogenic capacity (increased glucose excursion in response to pyruvate) and insulin sensitivity; and (e) show enhanced whole-body energy expenditure and induced lipid-utilizing phenotype after topical menthol application. Taken together, our findings highlight that pharmacological cold mimicking using topical menthol application presents a potential therapeutic strategy to counter weight gain and related complications.

ChREBP plays a pivotal role in the nutrient-mediated regulation of metabolic gene expression in brown adipose tissue

AimsCarbohydrate-responsive element-binding protein (ChREBP) is a transcription factor that regulates several metabolic genes, including the lipogenic enzymes necessary for the metabolic conversion of carbohydrates into lipids. Although the crucial role of ChREBP in the liver, the primary site of de novo lipogenesis, has been studied, its functional role in adipose tissues, particularly brown adipose tissue (BAT), remains unclear. In this study, we investigated the role of ChREBP in BAT under conditions of a high-carbohydrate diet (HCD) and ketogenic diet (KD), represented by extremely low carbohydrate intake. Main methodsUsing an adeno-associated virus and Cas9 knock-in mice, we rapidly generated Chrebp brown adipocyte-specific knock-out (B-KO) mice, bypassing the necessity for prolonged breeding by using the Cre-Lox system. Key findingsWe demonstrated that ChREBP is essential for glucose metabolism and lipogenic gene expression in BAT under HCD conditions in Chrebp B-KO mice. After nutrient intake, Chrebp B-KO attenuated the KD-induced expression of several inflammatory genes in BAT. SignificanceOur results indicated that ChREBP, a nutrient-sensing regulator, is indispensable for expressing a diverse range of metabolic genes in BAT.

PM2.5-induced cellular senescence drives brown adipose tissue impairment in middle-aged mice

Airborne fine particulate matter (PM2.5) exposure is closely associated with metabolic disturbance, in which brown adipose tissue (BAT) is one of the main contributing organs. However, knowledge of the phenotype and mechanism of PM2.5 exposure-impaired BAT is quite limited. In the study, male C57BL/6 mice at three different life phases (young, adult, and middle-aged) were simultaneously exposed to concentrated ambient PM2.5 or filtered air for 8 weeks using a whole-body inhalational exposure system. H&E staining and high-resolution respirometry were used to assess the size of adipocytes and mitochondrial function. Transcriptomics was performed to determine the differentially expressed genes in BAT. Quantitative RT-PCR, immunohistochemistry staining, and immunoblots were performed to verify the transcriptomics and explore the mechanism for BAT mitochondrial dysfunction. Firstly, PM2.5 exposure caused altered BAT morphology and mitochondrial dysfunction in middle-aged but not young or adult mice. Furthermore, PM2.5 exposure increased cellular senescence in BAT of middle-aged mice, accompanied by cell cycle arrest, impaired DNA replication, and inhibited AKT signaling pathway. Moreover, PM2.5 exposure disrupted apoptosis and autophagy homeostasis in BAT of middle-aged mice. Therefore, BAT in middle-aged mice was more vulnerable to PM2.5 exposure, and the cellular senescence-initiated apoptosis, autophagy, and mitochondrial dysfunction may be the mechanism of PM2.5 exposure-induced BAT impairment.

Excessive fat expenditure in MCT-induced heart failure rats is associated with BMAL1/REV-ERBα circadian rhythmic loop disruption

Fat loss predicts adverse outcomes in advanced heart failure (HF). Disrupted circadian clocks are a primary cause of lipid metabolic issues, but it's unclear if this disruption affects fat expenditure in HF. To address this issue, we investigated the effects of disruption of the BMAL1/REV-ERBα circadian rhythmic loop on adipose tissue metabolism in HF.50 Wistar rats were initially divided into control (n = 10) and model (n = 40) groups. The model rats were induced with HF via monocrotaline (MCT) injections, while the control group received equivalent solvent injections. After establishing the HF model, the model group was further subdivided into four groups: normal rhythm (LD), inverted rhythm (DL), lentivirus vector carrying Bmal1 short hairpin RNA (LV-Bmal1 shRNA), and empty lentivirus vector control (LV-Control shRNA) groups, each with 10 rats. The DL subgroup was exposed to a reversed light–dark cycle of 8 h: 16 h (dark: light), while the rest adhered to normal light–dark conditions (light: dark 12 h: 12 h). Histological analyses were conducted using H&E, Oil Red O, and Picrosirius red stains to examine adipose and liver tissues. Immunohistochemical staining, RT-qPCR, and Western blotting were performed to detect markers of lipolysis, lipogenesis, and beiging of white adipose tissue (WAT), while thermogenesis indicators were detected in brown adipose tissue (BAT). The LD group rats exhibited decreased levels of BMAL1 protein, increased levels of REV-ERBα protein, and disrupted circadian circuits in adipose tissue compared to controls. Additionally, HF rats showed reduced adipose mass and increased ectopic lipid deposition, along with smaller adipocytes containing lower lipid content and fibrotic adipose tissue. In the LD group WAT, expression of ATGL, HSL, PKA, and p-PKA proteins increased, alongside elevated mRNA levels of lipase genes (Hsl, Atgl, Peripilin) and FFA β-oxidation genes (Cpt1, acyl-CoA). Conversely, lipogenic gene expression (Scd1, Fas, Mgat, Dgat2) decreased, while beige adipocyte markers (Cd137, Tbx-1, Ucp-1, Zic-1) and UCP-1 protein expression increased. In BAT, HF rats exhibited elevated levels of PKA, p-PKA, and UCP-1 proteins, along with increased expression of thermogenic genes (Ucp-1, Pparγ, Pgc-1α) and lipid transportation genes (Cd36, Fatp-1, Cpt-1). Plasma NT-proBNP levels were higher in LD rats, accompanied by elevated NE and IL-6 levels in adipose tissue. Remarkably, morphologically, the adipocytes in the DL and LV-Bmal1 shRNA groups showed reduced size and lower lipid content, while lipid deposition in the liver was more pronounced in these groups compared to the LD group. At the gene/protein level, the BMAL1/REV-ERBα circadian loop exhibited severe disruption in LV-Bmal1 shRNA rats compared to LD rats. Additionally, there was increased expression of lipase genes, FFA β oxidation genes, and beige adipocyte markers in WAT, as well as higher expression of thermogenic genes and lipid transportation genes in BAT. Furthermore, plasma NT-proBNP levels and adipose tissue levels of NE and IL-6 were elevated in LV-Bmal1 shRNA rats compared with LD rats. The present study demonstrates that disruption of the BMAL1/REV-ERBα circadian rhythmic loop is associated with fat expenditure in HF. This result suggests that restoring circadian rhythms in adipose tissue may help counteract disorders of adipose metabolism and reduce fat loss in HF.

Electroacupuncture Mediates Fat Metabolism and Autophagy via a Sirt3-Dependent Mechanism in Mice Fed High-Fat Diet.

This study investigates the therapeutic potential of electroacupuncture (EA) on obesity, focusing on its influence on autophagy and energy metabolism, utilizing a high-fat diet (HFD)-induced mouse model. Treatment with EA significantly reduces body weight, fat deposition, and lipid accumulation in HFD-fed mice. Additionally, EA effectively ameliorates metabolic imbalances, reducing blood glucose levels and plasma markers of liver function. At the molecular level, EA enhances the expression of thermogenesis-associated genes in brown adipose tissue and decreases p53 expression, suggesting a decrease in apoptosis. Autophagy in white adipose tissue is inhibited by EA, as demonstrated by the suppression of key autophagy-related proteins. Further experiments highlight the critical role of Sirtuin 3 (Sirt3) in EA's anti-obesity effects. Sirt3 supplementation combined with EA results in reduced body weight, fat deposition, and lipid accumulation, along with modulations in key metabolic indicators. Moreover, EA's modulatory effect on uncoupling protein 1 (Ucp1), Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1α), and p53 is found to be Sirt3 dependent. In conclusion, EA exerts beneficial effects against obesity through Sirt3-dependent modulation of autophagy and energy metabolism, indicating a potential therapeutic approach for obesity and related metabolic disorders.

80-OR: A New Cytoskeleton-Based Mechanism for Regulating Brown Adipose Tissue Physiology

Human genetic variants in ANK2, encoding the scaffold protein ankyrin-B (AnkB), increase risk for T2D. We characterized the role of AnkB in white adipose tissue (WAT) in mice with AnkB deficiency in both WAT and brown adipose tissue (BAT) (AT-AnkB KO). We found that AnkB loss led to obesity and insulin resistance driven by its role in clathrin mediated endocytosis of GLUT4 in WAT. AT-AnkB KO mice also had lipid accumulation in BAT. However, the cell-autonomous roles of AnkB in BAT and its contribution to energy balance is unknown. To elucidate AnkB’s roles in BAT, we developed mice lacking AnkB in BAT (BAT-AnkB KO). Histology and TEM revealed lipid accumulation in BAT of 4-month-old BAT-AnkB KO mice housed at thermoneutrality. Consistent with this finding, brown adipocytes from AnkB deficient mice also have enlarged lipid droplets, suggesting an AnkB cell-autonomous role in BAT lipid homeostasis. Proteomic-MS revealed that AnkB forms complexes with lipolysis factors Atgl, Hsl and Plin1, and regulators of the PKA pathway, suggesting AnkB plays a role regulating BAT lipolysis. Interestingly, Hsl and Plin1 are elevated in BAT despite the enlarged LDs of BAT-AnkB KO mice, implying either lipolytic deficits or compensatory effects. These findings support RNA sequencing that revealed downregulation of PKA signaling genes, ATPase subunits, and mitochondrial calcium signaling genes in BAT of BAT-AnkB KO mice. Last, peri-droplet mitochondria (PDM), a mitochondria subpopulation with reduced beta-oxidation capacity that contacts LDs, form longer contact sites with BAT LDs from BAT-AnkB KO mice. Together, these findings suggest that early alterations in mitochondrial bioenergetics and lipolysis contribute to BAT LD accumulation. Along with this data, we will present findings on thermogenic regulation in vivo and physiological assays evaluating lipolysis and its major regulators. Disclosure A.Aguillard: None. J.Arricastres: None. J.Tzeng: None. D.Lorenzo: None. Funding American Diabetes Association (1-19-JDF-081 to D.L.); National Science Foundation; Burroughs Wellcome Fund (1022069)

76-OR: Axon Guidance Molecule Slit3 Is Essential for Cold-Induced Remodeling of BAT Neurovasculature and Thermogenesis

Brown adipose tissue (BAT) is primarily responsible for regulating body temperature through adaptive thermogenesis. Enhancing energy expenditure through the activation of BAT thermogenesis is a promising strategy to prevent and reverse obesity and its cardiometabolic sequelae. Brown adipocytes are embedded in a dense network of blood vessels and sympathetic nerves that supports their thermogenic activity. Increasing the density of blood vessels and sympathetic innervation is essential for enhanced thermogenesis in cold. However, how these distinct processes are spatiotemporally regulated is not clear. To define the mediators of intercellular crosstalk in the BAT, we used single-cell transcriptomic analysis of BAT to build a network of ligand-receptor interactions. We identified Slit guidance ligand 3 (Slit3) as a new adipokine that mediates the crosstalk among adipocyte progenitors, endothelial cells, and sympathetic nerves. Using a combination of in vivo gain and loss of function studies, we showed that Slit3 is essential for cold-induced angiogenesis and sympathetic innervation in BAT. Loss of Slit3 reduced the density of blood vessels and sympathetic neurites in BAT. Consequently, mice lacking Slit3 expression in BAT exhibited severe cold intolerance, increased lipid accumulation and whitening of BAT, and reduced expression of thermogenic and mitochondrial genes in BAT. Conversely, the overexpression of Slit3 enhanced cold-induced BAT thermogenesis. Our mechanistic studies identified the key regulatory events that control Slit3 signaling in BAT. Collectively, these findings established the essential role of Slit3 signaling in regulation of BAT thermogenesis and introduced Slit3 as a new niche factor that promotes adipose tissue health. These studies introduced a potential node of intervention for improving systemic metabolism through the expansion of thermogenic fat. Disclosure T.Duarte afonso serdan: None. H.E.Cervantes: None. F.M.Neto: None. Y.Tseng: Consultant; Cellarity, LyGenesis. F.Shamsi: None. Funding National Institutes of Health (K01DK125608)

Hepatic protein kinase Cbeta deficiency mitigates late-onset obesity

Although aging is associated with progressive adiposity and a decline in liver function, the underlying molecular mechanisms and metabolic interplay are incompletely understood. Here, we demonstrate that aging induces hepatic protein kinase Cbeta (PKCβ) expression, while hepatocyte PKCβ deficiency (PKCβHep-/-) in mice significantly attenuates obesity in aged mice fed a high-fat diet. Compared with control PKCβfl/fl mice, PKCβHep-/- mice showed elevated energy expenditure with augmentation of oxygen consumption and carbon dioxide production which was dependent on β3-adrenergic receptor signaling, thereby favoring negative energy balance. This effect was accompanied by induction of thermogenic genes in brown adipose tissue (BAT) and increased BAT respiratory capacity, as well as a shift to oxidative muscle fiber type with an improved mitochondrial function, thereby enhancing oxidative capacity of thermogenic tissues. Furthermore, in PKCβHep-/- mice, we determined that PKCβ overexpression in the liver mitigated elevated expression of thermogenic genes in BAT. In conclusion, our study thus establishes hepatocyte PKCβ induction as a critical component of pathophysiological energy metabolism by promoting progressive hepatic and extrahepatic metabolic derangements in energy homeostasis, contributing to late-onset obesity. These findings have potential implications for augmenting thermogenesis as a means of combating aging-induced obesity.

"Turning up the heat": Role of neurotrophic batokines in the postnatal maturation and remodelling of brown adipose tissue in deer mice.

Activation of brown adipose tissue (BAT) thermogenesis impacts energy balance and must be tightly regulated. Several neurotrophic factors, expressed in BAT of adult laboratory rodents, have been implicated in remodelling the sympathetic neural network to enhance thermogenesis (e.g., NGF, NRG4 and S100b). Here, we compare for the first time the relative roles of three neurotropic 'batokines' in establishing/remodelling innervation during postnatal development and adult cold stress. We used lab-reared P. maniculatus, which rely heavily on BAT-based thermogenesis for survival in the wild, beginning between postnatal days (P) 8 and 10. BAT sympathetic innervation was enhanced from P6-10, and exogenous NGF, NRG4, and S100b stimulated neurite outgrowth from P6 sympathetic neurons. Endogenous BAT protein stores and/or gene expression of NRG4, S100b, and calsyntenin-3ß (which regulates S100b secretion), remained high and constant during development. However, endogenous NGF was low and ngf mRNA was undetectable. Conditioned media (CM) from cultured P10 BAT slices stimulated neurite outgrowth from sympathetic neurons in vitro that was inhibited by antibodies against all three growth factors. P10 CM had significant amounts of secreted NRG4 and S100b protein, but not NGF. By contrast, BAT slices from cold-acclimated adults released significant amounts of all three factors relative to thermoneutral controls. These data suggest that while neurotrophic batokines regulate sympathetic innervation in vivo, their relative contributions differ depending on life stage. They also provide novel insight into the regulation of BAT remodelling and BAT's secretory role, which are both critical to our understanding of mammalian energy homeostasis.

Combined treatment with teneligliptin and canagliflozin additively suppresses high-fat diet-induced body weight gain in mice with modulation of lipid metabolism-related gene expression

In the treatment of type 2 diabetes mellitus (T2DM), comprehensive management of multiple risk factors, such as blood glucose, body weight, and lipids, is important to prevent disease progression. Although the combination of dipeptidyl peptidase-4 (DPP-4) inhibitor and sodium-glucose co-transporter 2 (SGLT2) inhibitor is often used clinically, the effects of this combination, other than glucose metabolism, have yet to be thoroughly investigated. In this study, we evaluated the effects of combined treatment with a DPP-4 inhibitor, teneligliptin, and an SGLT2 inhibitor, canagliflozin, on the body weight and lipid metabolism in high-fat diet (HFD)-induced obese mice. We found that monotherapy with teneligliptin or canagliflozin showed suppressive effects on high-fat diet-induced body weight gain and reduced inguinal white adipose tissue (iWAT) mass, and combined treatment additively reduced body weight gain and iWAT mass. Teneligliptin significantly increased oxygen consumption during the light phase, and this effect was preserved in the combined treatment. The combined treatment did not alter the mRNA expression levels of thermogenesis-related genes in adipose tissue but showed the tendency to additively induce mRNA of fatty acid oxidation-related genes in brown adipose tissue and tended to additively decrease mRNA of fatty acid synthesis-related genes in iWAT and liver tissues. These results suggest that combined treatment with teneligliptin and canagliflozin additively suppresses HFD-induced body weight gain with increasing oxygen consumption and modulating the expression of lipid metabolism-related genes. This combination therapy may provide effective body weight management for patients with T2DM and obesity.

Generation of Brown Fat-Specific Knockout Mice Using a Combined Cre-LoxP, CRISPR-Cas9, and Adeno-Associated Virus Single-Guide RNA System.

Brown adipose tissue (BAT) is an adipose depot specialized in energy dissipation that can also serve as an endocrine organ via the secretion of bioactive molecules. The creation of BAT-specific knockout mice is one of the most popular approaches for understanding the contribution of a gene of interest to BAT-mediated energy regulation. The conventional gene targeting strategy utilizing the Cre-LoxP system has been the principal approach to generate tissue-specific knockout mice. However, this approach is time-consuming and tedious. Here, we describe a protocol for the rapid and efficient knockout of a gene of interest in BAT using a combined Cre-LoxP, CRISPR-Cas9, and adeno-associated virus (AAV) single-guide RNA (sgRNA) system. The interscapular BAT is located in the deep layer between the muscles. Thus, the BAT must be exposed in order to inject the AAV precisely and directly into the BAT within the visual field. Appropriate surgical handling is crucial to prevent damage to the sympathetic nerves and vessels, such as the Sultzer's vein that connects to the BAT. To minimize tissue damage, there is a critical need to understand the three-dimensional anatomical location of the BAT and the surgical skills required in the technical steps. This protocol highlights the key technical procedures, including the design of sgRNAs targeting the gene of interest, the preparation of AAV-sgRNA particles, and the surgery for the direct microinjection of AAV into both BAT lobes for generating BAT-specific knockout mice, which can be broadly applied to study the biological functions of genes in BAT.

Preventing high-fat diet-induced obesity and related metabolic disorders by hydrodynamic transfer of Il-27 gene.

Interleukin-27 (IL-27) is a multifaceted heterodimer cytokine that exerts both pro-inflammatory and anti-inflammatory effects under different physiological conditions. IL-27 signaling plays a role in promoting energy expenditure through enhanced thermogenesis. The objective of the study is to determine the functional role of IL-27 in regulating weight gain, and glucose and lipid homeostasis in mice fed a high-fat diet (HFD). C57BL/6 mice were hydrodynamically transferred with pLIVE-IL-27 plasmids to achieve elevated level of IL-27 in blood and then kept on a HFD for 8 weeks. The impacts of Il-27 gene transfer on HFD-induced weight gain, adiposity, hepatic lipid accumulation, insulin resistance, glucose homeostasis and the mRNA levels of genes responsible for lipogenesis, glucose homeostasis and proinflammation were assessed by methods of biochemistry, histology, and molecular biology. Hydrodynamic gene transfer of Il-27 gene resulted in a peak level of serum IL-27 in mice at 14.5 ng/ml 24 h after gene transfer followed by a sustained level at 2 ng/ml. The elevated level of IL-27 blocked HFD-induced fat accumulation and weight gain without reducing food intake. It also prevented metabolic abnormities of liver steatosis and insulin resistance. IL-27 overexpression promoted expression of major thermogenic genes in brown adipose tissues; and attenuated chronic inflammation and macrophage infiltration into white adipose tissues. The results demonstrate that regulation of IL-27 level could be an effective strategy for management of obesity and obesity-related metabolic diseases.

Association of Type 2 Deiodinase Thr92Ala Polymorphism with Pediatric Obesity in Japanese Children: A Case-Control Study.

sGenetic factors play critical roles in the onset and progression of obesity. Brown adipose tissue (BAT) activity is also critical for adiposity. The objective of this study was to evaluate the prevalence and effects of BAT gene polymorphisms in pediatric obesity. This case-control study included 270 non-obese and 86 obese children. All participants underwent genotyping for type 2 deiodinase (DIO2) Thr92Ala (rs225014). The prevalence of the homozygous Ala/Ala allele of the DIO2 gene in the obese group was 15.1% versus 6.3% in the non-obese group, resulting in an odds ratio (OR) of 3.393 (p = 0.003). The results of this study indicate that the homozygous Ala/Ala allele of the DIO2 gene is associated with an increased risk of pediatric obesity and suggest that pediatric obesity might be suitable for assessing the association with gene polymorphisms related to BAT, especially DIO2 Thr92Ala.

The effect of Xuezhikang capsule on gene expression profile in brown adipose tissue of obese spontaneously hypertensive rats

Ethnopharmacological relevanceObesity is a critical threat to global health, and brown adipose tissue (BAT) is a potential target for the treatment of obesity and comorbidities. Xuezhikang Capsule (XZK), an extract of red yeast rice, has remarkable clinical efficacy and is widely used for the treatment of hyperlipidemia and coronary heart disease. However, its modulatory effect on BAT remains unknown. Aim of this studyThe aim of this study was to investigate the protective mechanism of XZK in the obese spontaneously hypertensive rat (SHR) model by evaluating the regulatory effect of XZK on the BAT gene profile through transcriptome sequencing. Materials and methodsThe SHRs were randomly divided into four groups: the standard chow diet (STD) group, the STD supplemented with 126 mg/kg of XZK group, the high-fat diet (HFD) group, and the HFD supplemented with 126 mg/kg of XZK group. All SHRs were fed for 18 weeks. The metabolic phenotypes, including body weight, fat mass, oral glucose tolerance test (OGTT), and serum glucose and lipid levels, was evaluated, and hematoxylin and eosin staining (H&E) staining was performed to evaluate the adipose tissue histopathological phenotype. Transcriptome sequencing was performed to determine the mechanism by which XZK improves the metabolic phenotype and the expression of key differential expression genes was verified by real-time quantitative polymerase chain reaction (qRT-PCR). ResultsXZK inhibited HFD-induced weight gain and adipose tissue remodeling in SHRs and prevented hypertrophy of epididymal adipocytes and maintained the brown fat phenotype. XZK intervention also improved glucose and lipid metabolism in SHRs, as suggested by a reduction in serum triglyceride (TG), low-density cholesterol (LDL-C), and fasting blood glucose (FBG) levels as well as increasing in serum high-density cholesterol (HDL-C) levels. Transcriptome sequencing analysis confirmed the regulatory effect of XZK on the gene expression profile of BAT, and the expression patterns of 45 genes were reversed by the XZK intervention. Additionally, the results of the transcriptome analysis of 10 genes that are important for brown fat function were in line with the results of qRT-PCR. ConclusionsXZK protected SHRs from HFD-induced obesity, inhibited fat accumulation and improved glucolipid metabolism. Additionally, the protective effect of XZK on the overall metabolism of obese SHRs might partly be related to its regulatory effect on the BAT gene expression profile. These findings might provide novel therapeutic strategies for obesity-related metabolic diseases in traditional Chinese medicine (TCM).

Autophagy-mediated NCOR1 degradation is required for brown fat maturation and thermogenesis

Brown adipose tissue (BAT) thermogenesis affects energy balance, and thereby it has the potential to induce weight loss and to prevent obesity. Here we document a macroautophagic/autophagic-dependent mechanism of PPARG activity regulation that induces brown adipose differentiation and thermogenesis, and that is mediated by TP53INP2. Disruption of TP53INP2-dependent autophagy reduced brown adipogenesis in cultured cells. In vivo specific-tp53inp2 ablation in brown precursor cells or in adult mice decreased the expression of thermogenic and mature adipocytes genes in BAT. As a result, TP53INP2-deficient mice had reduced UCP1 content in BAT and impaired maximal thermogenic capacity, leading to lipid accumulation and to positive energy balance. Mechanistically, TP53INP2 stimulates PPARG activity and adipogenesis in brown adipose cells by promoting the autophagic degradation of NCOR1, a PPARG co-repressor. Moreover, the modulation of TP53INP2 expression in BAT and in human brown adipocytes suggest that this protein increases PPARG activity during metabolic activation of brown fat. In all, we have identified a novel molecular explanation to the contribution of autophagy to BAT energy metabolism that could facilitate the design of therapeutic strategies against obesity and its metabolic complications.

Cytochrome P450 2E1 gene knockout or inhibition prevents obesity induced by high-fat diet via regulating energy expenditure

Cytochrome P450 2E1 (CYP2E1), an important member of the CYP metabolic enzyme family in the liver, regulates the disposal of drugs and the biotransformation of endogenous substances. Although previous studies have found that CYP2E1 is related to energy metabolism, the role of CYP2E1 in energy homeostasis remains unclear. Herein this study shows that the deletion of Cyp2e1 gene in rats can prevent obesity, fatty liver and insulin resistance induced by high-fat diet. Mechanism studies uncover that Cyp2e1 deficiency not only increases the expression of thermogenic genes in brown adipose tissue (BAT) and subcutaneous adipose tissue (SAT), but also promotes fatty acid metabolism in the liver and BAT. In particular, Cyp2e1 deficiency elevates energy expenditure through an increase of liver-generated acylcarnitines, which promote BAT thermogenesis and increase β-oxidation. Interestingly, disulfiram as a CYP2E1 inhibitor can also prevent obesity induced by high-fat diet in normal rats. In general, this study explains the relationship between CYP2E1 and energy metabolism, and provides a new perspective for the prevention and treatment of obesity.

Nutritional Ketosis, Aquaporins, and Energy Homeostasis

ObjectivesKetogenic diets (KDs), promoting nutritional ketosis, profoundly impact energetic metabolism, and are being widely used for weight loss purposes. Aquaporins (AQPs) are transmembrane channels that facilitate water and glycerol transport across cell membranes and are critical players in energy homeostasis. The axis of adipose AQP7/hepatic AQP9 assures the body’s glycerol homeostasis. Studies investigating the relation between KD, aquaporins, and energy homeostasis are scarce. MethodsApoE–/– mice were fed ad libitum a KD (Kcal%: 1/81/18, carbohydrate/fat/protein; n = 8) or a control diet (Kcal%: 70/11/18, carbohydrate/fat/protein; n = 7) for 12 weeks. Food consumption and body weight were determined weekly, and plasma was collected every 4 weeks for biochemical analyses. Upon euthanasia, the tissues involved in energy homeostasis, the liver, white adipose tissue (WAT), and brown adipose tissue (BAT), were collected for gene expression analysis. ResultsBodyweight gain (% to the initial weight) was similar in both groups (4.0 ± 1.1, KD-mice vs. 3.3 ± 1.3, controls), in spite of the profoundly different diet fat content, thus confirming the anti-obesogenic effect of the diet. The plasma concentration of the major ketone body, ß-hydroxybutyrate, was significantly elevated in KD (2,019 ± 87 vs. control, 418 ± 72 nM, mean ± SEM), confirming the presence of nutritional ketosis under this dietary condition. The transcript level for uncoupling protein 1 (Ucp1) gene in BAT of KD-fed mice was upregulated by 400%, compared to control-fed mice, unveiling a thermogenic effect of KD. Lastly, mice subjected to KD exhibited: in BAT, a significant KD-induced upregulation of Aqp9 transcripts suggesting the participation in the influx of excess plasma glycerol to fuel thermogenesis; in WAT, a downregulation of Aqp7, suggesting the non-utilization of adipocyte lipid droplets as fuel; in the liver, an Aqp7 up-regulation suggesting its participation in glycerol influx into hepatocytes. ConclusionsThe anti-obesogenic effect of KD was associated with the upregulation of thermogenic genes in BAT and with the modulation of AQPs expression patterns in BAT, WAT, and the liver Funding SourcesMagnetic Resonance Imaging Facility, The Huck Institutes of the Life Sciences, Penn State, USA Fundação para a Ciência e Tecnologia (FCT), Portugal.

1381-P: GDF15 Deficiency in Brown Adipose Tissue Does Not Affect Thermogenesis, but Exacerbates Diet-Induced Obesity

Growth and differentiation factor 15 (GDF15) is induced in brown adipocytes in response to thermogenic stimuli, as well as high-fat feeding in mice. However, whether brown adipose tissue (BAT) -derived GDF15 is required to regulate BAT thermogenesis or energy homeostasis is unclear. In the present study, we sought to test the hypothesis that BAT-derived GDF15 is necessary to mediate thermogenesis and systemic adaptations to diet-induced obesity (DIO) . We generated mice lacking GDF15 specifically in BAT by crossing Gdf15 floxed mice with mice harboring the Cre recombinase under the control of the Ucp1 promoter (GDF15 BAT KO) . GDF15 BAT KO mice were treated with the beta adrenoreceptor agonist CL316,243 (CL) for 5 days to induce thermogenesis, or fed a high-fat diet (60% fat content) for 12 weeks to induce DIO. CL treatment promoted a significant induction in Gdf15 mRNA levels in the BAT of WT mice, which, as expected, was prevented in KO mice. Nonetheless, serum GDF15 levels were similarly induced by CL in both WT and KO mice. CL-induced activation of thermogenic genes in BAT, such as Ucp1 and Dio2, was comparable between genotypes, and core body temperature was unchanged between WT and KO mice. After 12 weeks of high-fat feeding, KO mice had significantly increased body weight and fat mass relative to WT mice. However, food intake, locomotor activity and energy expenditure were unchanged between groups. Respiratory exchange ratio was significantly higher in KO mice, indicating a relative preference for carbohydrate as fuel. Although glucose tolerance was unchanged between genotypes, insulin sensitivity was impaired in KO mice. Taken together, our data indicates that BAT-derived GDF15 does not contribute to GDF15 circulating levels in response to CL treatment and is largely dispensable for CL-induced BAT thermogenesis. However, BAT-derived GDF15 seems to be required to regulate diet-induced weight gain and insulin sensitivity. Disclosure J.Jena: None. K.Kato: None. A.A.Marti: None. R.Pereira: None. Funding NIHDK125405

The Effect of Nutritional Ketosis on Aquaporin Expression in Apolipoprotein E-Deficient Mice: Potential Implications for Energy Homeostasis.

Ketogenic diets (KDs) are very low-carbohydrate, very high-fat diets which promote nutritional ketosis and impact energetic metabolism. Aquaporins (AQPs) are transmembrane channels that facilitate water and glycerol transport across cell membranes and are critical players in energy homeostasis. Altered AQP expression or function impacts fat accumulation and related comorbidities, such as the metabolic syndrome. Here, we sought to determine whether nutritional ketosis impacts AQPs expression in the context of an atherogenic model. To do this, we fed ApoE−/− (apolipoprotein E-deficient) mice, a model of human atherosclerosis, a KD (Kcal%: 1/81/18, carbohydrate/fat/protein) or a control diet (Kcal%: 70/11/18, carbohydrate/fat/protein) for 12 weeks. Plasma was collected for biochemical analysis. Upon euthanasia, livers, white adipose tissue (WAT), and brown adipose tissue (BAT) were used for gene expression studies. Mice fed the KD and control diets exhibited similar body weights, despite the profoundly different fat contents in the two diets. Moreover, KD-fed mice developed nutritional ketosis and showed increased expression of thermogenic genes in BAT. Additionally, these mice presented an increase in Aqp9 transcripts in BAT, but not in WAT, which suggests the participation of Aqp9 in the influx of excess plasma glycerol to fuel thermogenesis, while the up-regulation of Aqp7 in the liver suggests the involvement of this aquaporin in glycerol influx into hepatocytes. The relationship between nutritional ketosis, energy homeostasis, and the AQP network demands further investigation.