Genes In Brown Adipose Tissue Research Articles

Chronic stress inhibits hypothalamus-pituitary-thyroid axis and brown adipose tissue responses to acute cold exposure in male rats.

Cold exposure activates the hypothalamus-pituitary-thyroid (HPT) axis, response blunted by previous acute stress or corticosterone administration. Chronic stressors can decrease serum T3 concentration, and thyrotropin-releasing hormone (Trh) expression in the paraventricular nucleus (PVN), but impact onthe response to cold is unknown; this was studied in rats submitted to daily repeated restraint (rRes) that causes habituation of hypothalamus-pituitary-adrenal (HPA) axis response, or to chronic variable stress (CVS) that causes sensitization and hyperreactivity. Wistar male adult rats were submitted to rRes 30min/day, or to CVS twice a day, for 15 days. On day 16, rats were exposed 1h to either 5 or 21°C. Parameters of HPT and HPA axes activity and of brown adipose tissue (BAT) cold response were measured; gene expression in PVN and BAT, by RT-PCR; serum hormone concentration by radioimmunoassay or ELISA. Compared to naïve animals, Crh and corticosterone concentrations were attenuated at the end of rRes, but increased at the end of CVS treatments. Cold exposure increased mRNA levels of Crh, Trh, and serum concentration of thyrotropin in naïve, but not in rRes or CVS rats; corticosterone increased in all groups. Cold induced expression of thermogenic genes in BAT (Dio2 and Ucp1) in naïve but not in stressed rats; Adrb3 expression was differentially regulated. Both types of chronic stress blunted HPT and BAT responses to cold. Long-term stress effects on noradrenergic and/or hormonal signaling are likely responsible for HPT dysfunction and not the type of chronic stressor.

The Role Of COX2 In The Regulation Of Brown Adipose Tissue In Obesity By Aerobic Exercise

PURPOSE: The aim was to explore the regulation mechanism of aerobic exercise on brown adipose tissue (BAT) in obese mice and the role of COX2. METHODS: The mice were randomly divided into the control group (C, normal diet), obesity group (H, high-fat diet to establish obesity model) and the obesity exercise group (HE, high-fat diet and medium intensity treadmill training). Blood lipid and glucose were detected after 4 weeks. Differentially expression genes in scapula BAT were determined by mRNA expression profiles, and functional annotation and signal pathway enrichment were carried out. COX2 (VEGF signaling pathway) involved in key biological processes (BP) and pathway. ADRβ3 agonist Isoprenaline (activating VEGF pathway) and NS-398 (COX2 inhibitor) were used, and the distribution of lipid droplets, the glycerol level, and the expression of mRNA and protein in VEGF pathway in brown adipocytes were detected. RESULTS: High-fat diet could induce obesity, accompanied by increased blood glucose and lipid levels (2.03±0.09 vs. 4.54±0.3), reducing UCP1 levels (1 vs. 0.71±0.1) in BAT. Aerobic exercise could significantly reduce the obese mice weight (C: 26.21±0.57; H: 27.53±0.61; HE: 26.32±0.52) and blood glucose levels (C: 8.5±0.78; H: 10.22±1.77; HE: 8.25±1.33). The BP of up-regulated genes in group H/C were mainly enriched in immune system progression, inflammatory and immune response, down-regulated genes were lipid metabolism and oxidation reduction. The up-regulated genes in group HE/H were enriched in glycolipid metabolism, while the down-regulated genes were cell death and apoptosis. VEGF signaling pathway plays an important role in this process, and COX2 in the VEGF pathway played a central role by interaction analysis. Application of Isoprenaline could increase the glycerin level (12.8±1.38 vs. 31.27±3.49) and the protein expression of VEGFa (1 vs.1.34±0.12), COX2 (1 vs.1.49±0.22) and UCP1 (1 vs. 1.27±0.18); Simultaneous application of NS-398 could inhibit the protein expression of COX2 and UCP1 in brown adipocytes. CONCLUSIONS: Obesity could lead to disorder of glycolipid metabolism and inflammation of BAT. Aerobic exercise could activate BAT activity through VEGF-COX2 pathway to reduce adverse effects of obesity. Funded by FRF for the Central Universities of China (2018GJ017)

Effects of Royal Jelly and Tocotrienol Rich Fraction in obesity treatment of calorie-restricted obese rats: a focus on white fat browning properties and thermogenic capacity

BackgroundObesity has reached an alarming rate worldwide. Promoting thermogenesis via increasing the function of brown adipose tissue (BAT) or white adipose tissue (WAT) browning has been proposed as a new protective approach against obesity. The goal of this study was to evaluate the effects of Royal Jelly (RJ) and tocotrienol rich fraction (TRF) on BAT activation and WAT browning during calorie restriction diet (CRD) in obesity model.MethodsIn this experimental study, 50 obese Wistar rats were randomly divided into 5 groups and then received one of the following treatments for a period of 8-week: High-fat diet (HFD), CRD, RJ + CRD, TRF + CRD, and RJ + TRF + CRD. Effects of RJ and TRF, individually and in combination on body weight and the expression of key thermoregulatory genes in WAT and BAT were examined by quantitative real-time (qRT-PCR). Also, morphological alterations were assessed by hematoxylin and eosin staining.ResultsRJ (− 67.21 g ±4.84 g) and RJ + TRF (− 73.29 g ±4.51 g) significantly reduced weight gain relative to the CRD group (− 40.70 g ±6.50 g, P < 0.001). In comparison with the CRD group, RJ and RJ + TRF remarkably enhanced the uncoupling protein1 (UCP1) expression in WAT (5.81, 4.72 fold, P < 0.001) and BAT (4.99, 4.75 fold, P < 0.001). The expression of PR domain containing 16(PRDM 16), cAMP response element-binding protein1 (CREB1), P38 mitogen-activated protein kinases (P38MAPK), and Bone morphogenetic protein8B (BMP8B) have significantly increased following RJ and RJ + TRF treatments (P < 0.001). However, the expression levels of CCAAT/enhancer-binding protein beta (CEBPβ) and Bone morphogenetic protein7 (BMP7) did not remarkably change. Multilocular beige cells in WAT and compacted dense adipocytes were also observed in BAT of RJ and RJ + TRF received groups. TRF showed no substantial effects on the expression of the mentioned thermoregulatory genes and brown fat-like phenotype.ConclusionOur results suggest that, Royal Jelly promotes thermogenesis and browning of WAT, contributing to an increase in energy expenditure. Thus, Royal Jelly may give rise to a novel dietary choice to attenuate obesity.

Inhibition of Plasminogen Activator Inhibitor-1 Activation Suppresses High Fat Diet-Induced Weight Gain via Alleviation of Hypothalamic Leptin Resistance.

Leptin resistance is an important mechanism underlying the development and maintenance of obesity and is thus regarded as a promising target of obesity treatment. Plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue-type and urokinase-type plasminogen activators, is produced at high levels in adipose tissue, especially in states of obesity, and is considered to primarily be involved in thrombosis. PAI-1 may also have roles in inter-organ tissue communications regulating body weight, because PAI-1 knockout mice reportedly exhibit resistance to high fat diet (HFD)-induced obesity. However, the role of PAI-1 in body weight regulation and the underlying mechanisms have not been fully elucidated. We herein studied how PAI-1 affects systemic energy metabolism. We examined body weight and food intake of PAI-1 knockout mice fed normal chow or HFD. We also examined the effects of pharmacological inhibition of PAI-1 activity by a small molecular weight compound, TM5441, on body weight, leptin sensitivities, and expressions of thermogenesis-related genes in brown adipose tissue (BAT) of HFD-fed wild type (WT) mice. Neither body weight gain nor food intake was reduced in PAI-1 KO mice under chow fed conditions. On the other hand, under HFD feeding conditions, food intake was decreased in PAI-1 KO as compared with WT mice (HFD-WT mice 3.98 ± 0.08 g/day vs HFD-KO mice 3.73 ± 0.07 g/day, P = 0.021), leading to an eventual significant suppression of weight gain (HFD-WT mice 40.3 ± 1.68 g vs HFD-KO mice 34.6 ± 1.84 g, P = 0.039). Additionally, TM5441 treatment of WT mice pre-fed the HFD resulted in a marked suppression of body weight gain in a PAI-1-dependent manner (HFD-WT-Control mice 37.6 ± 1.07 g vs HFD-WT-TM5441 mice 33.8 ± 0.97 g, P = 0.017). TM5441 treatment alleviated HFD-induced systemic and hypothalamic leptin resistance, before suppression of weight gain was evident. Moreover, improved leptin sensitivity in response to TM5441 treatment was accompanied by increased expressions of thermogenesis-related genes such as uncoupling protein 1 in BAT (HFD-WT-Control mice 1.00 ± 0.07 vs HFD-WT-TM5441 mice 1.32 ± 0.05, P = 0.002). These results suggest that PAI-1 plays a causative role in body weight gain under HFD-fed conditions by inducing hypothalamic leptin resistance. Furthermore, they indicate that pharmacological inhibition of PAI-1 activity is a potential strategy for alleviating diet-induced leptin resistance in obese subjects.

Phosphocholine accumulation and PHOSPHO1 depletion promote adipose tissue thermogenesis

Phosphocholine phosphatase-1 (PHOSPHO1) is a phosphocholine phosphatase that catalyzes the hydrolysis of phosphocholine (PC) to choline. Here we demonstrate that the PHOSPHO1 transcript is highly enriched in mature brown adipose tissue (BAT) and is further induced by cold and isoproterenol treatments of BAT and primary brown adipocytes. In defining the functional relevance of PHOPSPHO1 in BAT thermogenesis and energy metabolism, we show that PHOSPHO1 knockout mice are cold-tolerant, with higher expression of thermogenic genes in BAT, and are protected from high-fat diet-induced obesity and development of insulin resistance. Treatment of mice with the PHOSPHO1 substrate phosphocholine is sufficient to induce cold tolerance, thermogenic gene expression, and allied metabolic benefits. Our results reveal a role of PHOSPHO1 as a negative regulator of BAT thermogenesis, and inhibition of PHOSPHO1 or enhancement of phosphocholine represent innovative approaches to manage the metabolic syndrome.

46-OR: The Transcriptional Coregulator Ldb1 Directly Regulates Brown Adipose Thermogenic Function

Brown adipose tissue (BAT) is critical for mammalian thermogenesis. BAT utilizes fatty acids and glucose for heat production via mitochondrial uncoupling and is thus an attractive therapeutic target for combatting obesity. Exploiting the energy uncoupling capacity of this tissue will require a greater understanding of underlying BAT transcriptional mechanisms. Our prior work using a global deficiency model supported a novel role for the LIM domain-binding protein 1 (Ldb1) transcriptional co-regulator in regulating BAT function. However, direct roles for Ldb1 expressed in brown adipocytes has not been tested. Ldb1 acts as a scaffold to promote the assembly of transcriptional complexes and is important for the development and function of several metabolic tissues. We hypothesized that Ldb1 maintains BAT thermogenic function through direct regulation of thermogenic genes, like Ucp1. Loss of Ldb1 in primary brown adipocytes resulted in reduced expression of BAT-selective genes including Ucp1 and Elovl3 and the inability to induce Ucp1 expression upon Beta-3 adrenergic receptor agonism. This result was replicated using a siLdb1-transfected Ucp1-expressing cell line. To test Ldb1 roles on systemic thermogenesis, we developed a mouse model, termed Ldb1ΔBAT, where Ldb1 was reduced in thermogenic adipocytes using a Ucp1-driven Cre recombinase. Similar to our in vitro observations, Ldb1ΔBAT mice had reduced mRNAs of key BAT genes, including Ucp1 and Cidea. Through indirect calorimetry and a cold challenge, we uncovered significant impairments in energy expenditure and cold intolerance in Ldb1ΔBAT mice. To assess the transcriptional mechanisms underlying Ldb1 impacts on BAT thermogenesis, we conducted chromatin immunoprecipitation and found Ldb1 occupied upstream regulatory domains of Ucp1 in chromatin prepared from a BAT cell line and primary tissue. Overall, this work supports that Ldb1 is required for the thermogenic function of brown adipocytes. Disclosure J. Kepple: None. Y. Liu: None. T. Kim: None. K.M. Habegger: Consultant; Self; Glyscend, Inc. Research Support; Self; Daiichi Sankyo, Novo Nordisk Inc. M. Young: None. C.S. Hunter: None. Funding National Institutes of Health (R01DK111483, F31DK121414, T32GM109780)

Threonine, but Not Lysine and Methionine, Reduces Fat Accumulation by Regulating Lipid Metabolism in Obese Mice.

Some amino acids (AAs) have been proven to suppress fat mass and improve insulin sensitivity. However, the impact of important essential AAs, threonine, lysine, and methionine, on obesity has not been clarified. In the present study, after an 8 week period of obesity induction, mice were grouped to receive either a high-fat diet (HFD) or HFD supplemented with lysine, threonine, or methionine (3% in drinking water) for another 10 weeks. The results showed that dietary supplementation with threonine significantly decreased body weight, epididymal and perirenal fat pad weights, serum concentrations of glucose, triacylglycerols, total cholesterol, and LDL-cholesterol compared to the HFD group. HOMA-IR and serum leptin and adiponectin were improved by threonine supplementation. In epididymal adipose tissue, threonine treatment significantly down-regulated the expression levels of lipogenesis and up-regulated expressions of lipolysis compared to the HFD group. Threonine addition stimulated the expression of UCP-1 and related genes in brown adipose tissue. However, lysine or methionine supplementation showed little effect on body weight, WAT weight, serum lipid profiles, and lipid-metabolism-related gene expressions of HFD-fed mice. These findings suggest that threonine inhibited fat mass and improved lipid metabolism of already obese mice, providing a potential agent in treating obesity.

Epigenetic dynamics of the thermogenic gene program of adipocytes.

Brown adipose tissue (BAT) is a metabolically beneficial organ capable of burning fat by dissipating chemical energy into heat, thereby increasing energy expenditure. Moreover, subcutaneous white adipose tissue can undergo so-called browning/beiging. The recent recognition of the presence of brown or beige adipocytes in human adults has attracted much attention to elucidate the molecular mechanism underlying the thermogenic adipose program. Many key transcriptional regulators critical for the thermogenic gene program centering on activating the UCP1 promoter, have been discovered. Thermogenic gene expression in brown adipocytes rely on co-ordinated actions of a multitude of transcription factors, including EBF2, PPARγ, Zfp516 and Zc3h10. These transcription factors probably integrate into a cohesive network for BAT gene program. Moreover, these transcription factors recruit epigenetic factors, such as LSD1 and MLL3/4, for specific histone signatures to establish the favorable chromatin landscape. In this review, we discuss advances made in understanding the molecular mechanism underlying the thermogenic gene program, particularly epigenetic regulation.

Eriocitrin Improves Adiposity and Related Metabolic Disorders in High-Fat Diet-Induced Obese Mice

Eriocitrin (EC) is an abundant flavonoid in lemons, which is known as a strong antioxidant agent. This study investigated the biological and molecular mechanisms underlying the anti-obesity effect of EC in high-fat diet (HFD)-fed obese mice. C57BL/6N mice were fed an HFD (40 kcal% fat) with or without 0.005% (w/w) EC for 16 weeks. Dietary EC improved adiposity by increasing adipocyte fatty acid (FA) oxidation, energy expenditure, and mRNA expression of thermogenesis-related genes in brown adipose tissue (BAT) and skeletal muscle, whereas it also decreased lipogenesis-related gene expression in white adipose tissue. In addition to adiposity, EC prevented hepatic steatosis by diminishing lipogenesis while enhancing FA oxidation in the liver and fecal lipid excretion, which was linked to attenuation of hyperlipidemia. Moreover, EC improved insulin sensitivity by decreasing hepatic gluconeogenesis and proinflammatory responses. These findings indicate that EC may protect against diet-induced adiposity and related metabolic disorders by controlling thermogenesis of BAT and skeletal muscle, FA oxidation, lipogenesis, fecal lipid excretion, glucose utilization, and gluconeogenesis.

Lifespan of long-lived growth hormone receptor knockout mice was not normalized by housing at 30°C since weaning.

Growth hormone receptor knockout (GHRKO) mice are remarkably long‐lived and have improved glucose homeostasis along with altered energy metabolism which manifests through decreased respiratory quotient (RQ) and increased oxygen consumption (VO2). Short‐term exposure of these animals to increased environmental temperature (eT) at 30°C can normalize their VO2 and RQ. We hypothesized that increased heat loss in the diminutive GHRKO mice housed at 23°C and the consequent metabolic adjustments to meet the increased energy demand for thermogenesis may promote extension of longevity, and preventing these adjustments by chronic exposure to increased eT will reduce or eliminate their longevity advantage. To test these hypotheses, GHRKO mice were housed at increased eT (30°C) since weaning. Here, we report that contrasting with the effects of short‐term exposure of adult GHRKO mice to 30°C, transferring juvenile GHRKO mice to chronic housing at 30°C did not normalize the examined parameters of energy metabolism and glucose homeostasis. Moreover, despite decreased expression levels of thermogenic genes in brown adipose tissue (BAT) and elevated core body temperature, the lifespan of male GHRKO mice was not reduced, while the lifespan of female GHRKO mice was increased, along with improved glucose homeostasis. The results indicate that GHRKO mice have intrinsic features that help maintain their delayed, healthy aging, and extended longevity at both 23°C and 30°C.

HuR expression in adipose tissue mediates energy expenditure and acute thermogenesis independent of UCP1 expression

ABSTRACT The goal of this study was to define the functional role of adipocyte-specific expression of the RNA binding protein Human antigen R (HuR). Mice with an adipocyte-specific deletion of HuR (Adipo-HuR−/- ) were generated by crossing HuR floxed (HuRfl/fl ) mice with mice expressing adiponectin-driven cre-recombinase (Adipoq-cre). Our results show that Adipo-HuR−/- mice display a lean phenotype compared to wild-type littermate controls. HuR deletion results in a diet-independent reduction in percent body fat composition along with an increase in energy expenditure. Functionally, Adipo-HuR−/- mice show a significant impairment in acute adaptive thermogenesis (six hours at 4°C), but uncoupling protein 1 (UCP1) protein expression in brown adipose tissue (BAT) is unchanged compared to control. Pharmacological inhibition of HuR also results in a marked decline in core body temperature following acute cold challenge independent of UCP1 protein expression. Among the 588 HuR-dependent genes in BAT identified by RNA-seq analysis, gene ontology analysis shows a significant enrichment in mediators of calcium transport and signalling, almost all of which are decreased in Adipo-HuR−/- mice compared to control. In conclusion, adipocyte expression of HuR plays a central role in metabolic homoeostasis and mediates UCP1-independent thermogenesis in BAT, potentially through post-transcriptional control of intracellular calcium transport.Abbreviations: Adipo-HuR−/-: Adipocyte-specific HuR deletion mice; BAT: Brown adipose tissue; HuR: Human antigen R; UCP1: Uncoupling protein 1

Conditional knockout of kisspeptin signaling in brown adipose tissue increases metabolic rate and body temperature and lowers body weight.

The peptide kisspeptin and its receptor, Kiss1r, act centrally to stimulate reproduction. Evidence indicates that kisspeptin signaling is also important for body weight (BW) and metabolism. We recently reported that Kiss1r KO mice develop obesity, along with reduced metabolism and energy expenditure, independent of estradiol levels. Outside the brain, Kiss1r is expressed in several metabolic tissues, including brown adipose tissue (BAT), but it is unknown which specific tissue is responsible for the metabolic phenotype in Kiss1r KOs. We first determined that global Kiss1r KO mice have significant alterations in body temperature and BAT thermogenic gene expression, perhaps contributing to their obesity. Next, to test whether kisspeptin signaling specifically in BAT influences BW, metabolism, or body temperature, we used Cre/lox technology to generate conditional Kiss1r knockout exclusively in BAT (BAT-Kiss1r KO). Unlike global Kiss1r KOs, BAT-Kiss1r KOs (lacking Kiss1r in just BAT) were not hypogonadal, as expected. Surprisingly, however, BAT-Kiss1r KOs of both sexes displayed significantly lower BW and adiposity than controls. This novel BAT-Kiss1r KO phenotype was of greater magnitude in females and was associated with improved glucose tolerance, increased metabolism, energy expenditure, and locomotor activity, along with increased body temperature and BAT gene expression, specifically Cox8b. Our findings suggest that the previously observed obesity and decreased metabolism in global Kiss1r KOs reflect impaired kisspeptin signaling in non-BAT tissues. However, the novel finding of increased metabolism and body temperature and lower BW in BAT-Kiss1r KOs reveal a previously unidentified role for endogenous kisspeptin signaling in BAT in modulating metabolic and thermogenic physiology.

Altered adipocyte differentiation and unbalanced autophagy in type 2 Familial Partial Lipodystrophy: an in vitro and in vivo study of adipose tissue browning

Type-2 Familial Partial Lipodystrophy is caused by LMNA mutations. Patients gradually lose subcutaneous fat from the limbs, while they accumulate adipose tissue in the face and neck. Several studies have demonstrated that autophagy is involved in the regulation of adipocyte differentiation and the maintenance of the balance between white and brown adipose tissue. We identified deregulation of autophagy in laminopathic preadipocytes before induction of differentiation. Moreover, in differentiating white adipocyte precursors, we observed impairment of large lipid droplet formation, altered regulation of adipose tissue genes, and expression of the brown adipose tissue marker UCP1. Conversely, in lipodystrophic brown adipocyte precursors induced to differentiate, we noticed activation of autophagy, formation of enlarged lipid droplets typical of white adipocytes, and dysregulation of brown adipose tissue genes. In agreement with these in vitro results indicating conversion of FPLD2 brown preadipocytes toward the white lineage, adipose tissue from FPLD2 patient neck, an area of brown adipogenesis, showed a white phenotype reminiscent of its brown origin. Moreover, in vivo morpho-functional evaluation of fat depots in the neck area of three FPLD2 patients by PET/CT analysis with cold stimulation showed the absence of brown adipose tissue activity. These findings highlight a new pathogenetic mechanism leading to improper fat distribution in lamin A-linked lipodystrophies and show that both impaired white adipocyte turnover and failure of adipose tissue browning contribute to disease.

Ghrelin receptor in agouti-related peptide neurones regulates metabolic adaptation to calorie restriction.

Ghrelin is a gut hormone that signals to the hypothalamus to stimulate growth hormone release, increase food intake and promote fat deposition. The ghrelin receptor, also known as growth hormone secretagogue receptor (GHS-R), is highly expressed in the brain, with the highest expression in agouti-related peptide (AgRP) neurones in the hypothalamus. Compelling evidence indicates that ghrelin serves as a survival hormone with respect to maintaining blood glucose and body weight during nutritional deficiencies. Recent studies have demonstrated that AgRP neurones are involved in metabolic and behavioural adaptation to an energy deficit to improve survival. In the present study, we used a neuronal subtype-specific GHS-R knockout mouse (AgRP-Cre;Ghsrf/f ) to investigate the role of GHS-R in hypothalamic AgRP neurones in metabolic and behavioural adaptation to hypocaloric restricted feeding. We subjected the mice to a restricted feeding regimen of 40% mild calorie restriction (CR), with one-quarter of food allotment given in the beginning of the light cycle and three-quarters given at the beginning of the dark cycle, to mimic normal mouse intake pattern. The CR-fed AgRP-Cre;Ghsrf/f mice exhibited reductions in body weight, fat mass and blood glucose. Metabolic profiling of these CR-fed AgRP-Cre;Ghsrf/f mice showed a trend toward reduced basal metabolic rate, significantly reduced core body temperature and a decreased expression of thermogenic genes in brown adipose tissue. This suggests a metabolic reset to a lower threshold. Significantly increased physical activity, a trend toward increased food anticipatory behaviour and altered fuel preferences were also observed in these mice. In addition, these CR-fed AgRP-Cre;Ghsrf/f mice exhibited a decreased counter-regulatory response, showing impaired hepatic glucose production. Lastly, hypothalamic gene expression in AgRP-Cre;Ghsrf/f mice revealed increased AgRP expression and a decreased expression of genes in β-oxidation pathways. In summary, our data suggest that GHS-R in AgRP neurones is a key component of the neurocircuitry involved in metabolic adaptation to calorie restriction.

Effect of Quercetin on Non-shivering Thermogenesis and Intestinal Microbial Populations (P06-037-19)

ObjectivesActivation of non-shivering thermogenesis in adipose tissues and alteration in intestinal microbiome have been linked with improved obese condition. With emerging evidences of dietary compounds to prevent obesity, the objective of this study was to examine whether quercetin activates non-shivering thermogenesis in adipose tissues and influences intestinal microbiome, which eventually improves obese condition. MethodsFour-week-old C57BL/6 male mice were fed either a low-fat diet (LFD) or a high-fat diet (HFD) with or without 1% quercetin (Q) for 16 weeks. On the completion of the feeding study, brown adipose tissue (BAT), white adipose tissue (WAT), and cecum were collected. Total RNA was extracted from BAT and WAT, and then cDNA was synthesized. The expression of genes that are involved in the regulation of non-shivering thermogenesis such as uncoupling protein 1 (ucp1), cell death-inducing DFFA-like effector A (cidea), peroxisome proliferator-activated receptor gamma (pparγ), pparγ-coactivator 1 alpha (pgc1α), fibroblast growth factor 21 (fgf21), positive regulatory domain containing 16 (prdm16), and T-box protein 1 (tbx1) were determined by a real-time PCR. The expression of the proteins such as UCP1 and AMP-activated protein kinase (AMPK) was assessed by western blot analysis. Microbial populations in cecum were analyzed via the Illumnia MiSeq sequencing platform and QIIME (Quantitative Insights Into Microbial Ecology) Software. ResultsMice fed HFDQ showed reduced body weight and retroperitoneal (R) WAT weight compared to mice fed HFD. Quercetin supplementation increased the expression of ucp1, prdm16, pgc1α, cidea, and tbx1 genes in BAT and RWAT of mice fed HFD. The expression of UCP1 protein and phosphorylation of AMPK were increased. However, browning effect was not observed in other WATs. Mice fed LFDQ and HFDQ exhibited higher relative abundance of Bacteroidetes than mice fed LFD and HFD whereas the relative abundance of Firmicutes was decreased. ConclusionsQuercetin may be a potential dietary compound that increases energy metabolism by activating BAT and attracting beige adipocytes in RWAT. In addition, quercetin-induced energy metabolism may have a correlation with changes of microbial populations in intestine. Funding SourcesThe work was supported by USDA.

Prenylated flavonoid-standardized extract from seeds of Psoralea corylifolia L. activated fat browning in high-fat diet-induced obese mice.

We investigated the effects of the prenylated flavonoid-standardized extract (PFE) from the seeds of Psoralea corylifolia L. on countering obesity, which increases energy expenditure and stimulates thermogenesis in subcutaneous white adipose tissue (sWAT) and brown adipose tissue (BAT). For 12weeks, C57BL/6 mice were fed a controlled high-fat diet (HFD) or HFDs with 0.2% or 0.5% w/w PFE. In vitro, the differentiation of 3T3-L1 cells was used to elicit thermogenesis in the presence of PFE. PFE obviously reduced body weight and fat mass in a dose-dependent manner, increased energy expenditure, improved insulin sensitivity, and prevented hepatic steatosis by increasing lipid oxidation and secretion in HFD-fed mice. Moreover, PFE induced clear browning in sWAT, significantly increased phosphorylation of AMPKα1/2 and p38, increased BAT activity and the differentiation of 3T3-L1 by increasing the expression of uncoupling protein 1 and other thermogenic genes. Our study showed that PFE prevented obesity by increasing browning and activating thermogenic genes in sWAT and BAT, improving glucose homeostasis, and protecting hepatic steatosis.

Siah2 modulates sex-dependent metabolic and inflammatory responses in adipose tissue to a high-fat diet challenge

BackgroundThe obesity-related risk of developing metabolic syndrome is higher in males than in females of reproductive age, likely due to estrogen-mediated reduced adipose tissue inflammation and fibrosis with hypertrophied adipocytes. Depletion of the ubiquitin ligase Siah2 reduced white adipose tissue inflammation and improved glucose metabolism in obese male mice. Siah2 is a transcriptional target of estrogen, but data is lacking about the effect of Siah2 on adipose tissue of females. We therefore evaluated the impact of Siah2 deficiency on white and brown adipose tissue in females of reproductive age.MethodsBody composition, adipose tissue morphology, brown adipose tissue gene, and protein expression and adipocyte sizing were evaluated in wild-type and Siah2KO female and male mice fed a low-fat or high-fat diet. Glucose and insulin tolerance, fasting glucose, insulin, fatty acids and triglycerides, and gene expression of inflammation markers in perigonadal fat were evaluated in wild-type and Siah2KO female mice. Microarray analysis of brown fat gene expression was carried out in both sexes. Statistical analysis was assessed by unpaired two-tailed t test and repeated measures ANOVA.ResultsSiah2 deficiency improves glucose and insulin tolerance in the presence of hypertrophied white adipocytes in high-fat-fed female mice with percent fat comparable to male mice. While previous studies showed Siah2KO reduces the white adipose tissue inflammatory response in male mice, the response in females is biased toward the upregulation of M2-like markers in white adipose tissue. In contrast, loss of Siah2 leads to increased whitening of brown fat in males, but not in females. This corresponded to increased expression of markers of inflammation (F4/80, Ccl2) and thermogenic genes (Pgc1alpha, Dio2, Ucp-1) and proteins (PGC-1α, UCP-1) in females. Contrary to expectations, increased expression of thermogenic markers in females was coupled with a downregulation of ERalpha and ERRgamma protein levels.ConclusionsThe most striking sex-related effect of Siah2 deficiency is reduced whitening of brown fat in high-fat-fed females. Protection from accumulating unilocular adipocytes in the brown fat corresponds to increased expression of thermogenic genes and proteins in female, but not in male mice. These results raise the possibility that Siah2 contributes to the estrogen-related effects on brown fat function in males and females.

RDH1 suppresses adiposity by promoting brown adipose adaptation to fasting and re-feeding.

RDH1 is one of the several enzymes that catalyze the first of the two reactions to convert retinol into all-trans-retinoic acid (atRA). Here, we show that Rdh1-null mice fed a low-fat diet gain more weight as adiposity (17% males, 13% females) than wild-type mice by 20weeks old, despite neither consuming more calories nor decreasing activity. Glucose intolerance and insulin resistance develop following increased adiposity. Despite the increase in white fat pads, epididymal white adipose does not express Rdh1, nor does muscle. Brown adipose tissue (BAT) and liver express Rdh1 at relatively high levels compared to other tissues. Rdh1 ablation lowered body temperatures during ambient conditions. Given the decreased body temperature, we focused on BAT. A lack of differences in BAT adipogenic gene expression between Rdh1-null mice and wild-type mice, including Pparg, Prdm16, Zfp516 and Zfp521, indicated that the phenotype was not driven by brown adipose hyperplasia. Rather, Rdh1 ablation eliminated the increase in BAT atRA that occurs after re-feeding. This disruption of atRA homeostasis increased fatty acid uptake, but attenuated lipolysis in primary brown adipocytes, resulting in increased lipid content and larger lipid droplets. Rdh1 ablation also decreased mitochondrial proteins, including CYCS and UCP1, the mitochondria oxygen consumption rate, and disrupted the mitochondria membrane potential, further reflecting impaired BAT function, resulting in both BAT and white adipose hypertrophy. RNAseq revealed dysregulation of 424 BAT genes in null mice, which segregated predominantly into differences after fasting vs after re-feeding. Exceptions were Rbp4 and Gbp2b, which increased during both dietary conditions. Rbp4 encodes the serum retinol-binding protein-an insulin desensitizer. Gbp2b encodes a GTPase. Because Gbp2b increased several hundred-fold, we overexpressed it in brown adipocytes. This caused a shift to larger lipid droplets, suggesting that GBP2b affects signaling downstream of the β-adrenergic receptor during basal thermogenesis. Thus, Rdh1-generated atRA in BAT regulates multiple genes that promote BAT adaptation to whole-body energy status, such as fasting and re-feeding. These gene expression changes promote optimum mitochondria function and thermogenesis, limiting adiposity. Attenuation of adiposity and insulin resistance suggests that RDH1 mitigates metabolic syndrome.

Loss of glucagon signaling alters white adipose tissue browning.

Various endocrine factors contribute to cold-induced white adipose tissue (WAT) browning, but glucagon has largely been ignored. The purpose of the current investigation was to determine if glucagon was required for the effects of cold on WAT browning. Utilizing whole-body glucagon receptor knockout (Gcgr-/-) mice and their wild-type (WT) littermate controls, we examined the response of inguinal WAT (iWAT) and interscapular brown adipose tissue (BAT) to an acute (48 h) cold stress or challenge with the β3-adrenergic agonist CL316,243. The effects of glucagon alone on the induction of thermogenic genes in adipose tissue from C57BL6/J mice were also examined. Gcgr-/- mice displayed modest increases in indices of browning at room temperature while displaying a blunted induction of Ucp1, Cidea, and Ffg21 mRNA expression in iWAT following cold exposure. Similarly, cold induced increases in mitochondrial DNA copy number, and the protein content of mitochondrial respiratory chain complexes, UCP1, and PGC1α were attenuated in iWAT from Gcgr-/- mice. In BAT, the induction of thermogenic markers following cold exposure was reduced, but the effect was less pronounced than in iWAT. Glucagon treatment increased the expression of thermogenic genes in both iWAT and BAT of C57BL6/J mice. In response to CL316,243, circulating fatty acids, glycerol, and the phosphorylation of hormone-sensitive lipase were attenuated in iWAT of Gcgr-/- mice. We provide evidence that glucagon is sufficient for the induction of thermogenic genes in iWAT, and the absence of intact glucagon signaling blunts the cold-induced browning of WAT, possibly due, in part, to impaired adrenergic signaling.-Townsend, L. K., Medak, K. D., Knuth, C. M., Peppler, W. T., Charron, M. J., Wright, D. C. Loss of glucagon signaling alters white adipose tissue browning.

Isolated compounds from Cuscuta pedicellata ameliorate oxidative stress and upregulate expression of some energy regulatory genes in high fat diet induced obesity in rats.

Cuscuta pedicellata and some of its isolated compounds were suggested previously to have an anti-obesity effect in rats. This study aimed to investigate the effect of ten isolated compounds from C. pedicellata on insulin resistance, some oxidative stress markers and expression of the mitochondrial uncoupling protein-1 (UCP-1) and Carnitine palmitoyltransferase-I (CPT-1) genes in brown adipose tissue of high fat diet (HFD) rats. One hundred and four male albino rats were divided into 13 groups. Group (1) was considered as normal untreated rats. Obesity was induced in all other groups by HFD. Group (2) served as obese control group and groups (3-11) were treated for four weeks with C. pedicellata extract or one of its isolated compounds (naringenin, kaempferol, aromadenderin, quercetin, 3,5,7,30,50-pentahydroxy flavanone, naringenin-7-O-b-d-glucoside, aromadenderin-7-O-b-d-glucoside, taxifolin 7-O-b-d-glucoside, kaempferol-3-O-b-d-glucoside [astragalin], and quercitin-3-O-b-d-glucoside [isoquercitrin]). At the end of the experiment, rats were then sacrificed under anesthesia and their brown adipose tissues were dissected out for determination of UCP-1 and CPT-1 genes using quantitative PCR. Blood samples were collected for determination of blood glucose, insulin, thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) and catalase. A significant reduction in homeostasis model assessment-insulin resistance (HOMA-IR) and TBARS levels was observed in rats treated with C. pedicellata crude extract and some of its isolated compounds, with a significant increase in SOD and catalase levels and upregulation of UCP-1 and CPT-1 genes expression compared to the obese control group. This study suggests a beneficiary role of C. pedicellata in reducing insulin resistance, oxidative stress and enhancing energy expenditure.