Quercetin attenuates adipose hypertrophy,in part through activation of adipogenesis in rats fed a high-fat diet

An impaired capacity of adipose tissue expansion leads to adipocyte hypertrophy, inflammation and insulin resistance (IR) under positive energy balance. We previously showed that a grape pomace extract, rich in flavonoids including quercetin (Q), attenuates adipose hypertrophy. This study investigated whether dietary Q supplementation promotes adipogenesis in the epididymal white adipose tissue (eWAT) of rats consuming a high-fat diet, characterizing key adipogenic regulators in 3T3-L1 pre-adipocytes. Consumption of a high-fat diet for 6 weeks caused IR, increased plasma TNFα concentrations, eWAT weight, adipocyte size and the eWAT/brown adipose tissue (BAT) ratio. These changes were accompanied by decreased levels of proteins involved in angiogenesis, VEGF-A and its receptor 2 (VEGF-R2), and of two central adipogenic regulators, i.e. PPARγ and C/EBPα, and proteins involved in mature adipocyte formation, i.e. fatty acid synthase (FAS) and adiponectin. Q significantly reduced adipocyte size and enhanced angiogenesis and adipogenesis without changes in eWAT weight and attenuated systemic IR and inflammation. In addition, high-fat diet consumption increased eWAT hypoxia inducible factor-1 alpha (HIF-1α) levels and those of proteins involved in adipose inflammation (TLR-4, CD68, MCP-1, JNK) and activation of endoplasmic reticulum (ER) stress, i.e. ATF-6 and XBP-1. Q mitigated all these events. Q and quercetin 3-glucoronide prevented TNFα-mediated downregulation of adipogenesis during 3T3-L1 pre-adipocytes early differentiation. Together, Q capacity to promote a healthy adipose expansion enhancing angiogenesis and adipogenesis may contribute to reduced adipose hypertrophy, inflammation and IR. Consumption of diets rich in Q could be useful to counteract the adverse effects of high-fat diet-induced adipose dysfunction.     

Exercise ameliorates high-fat diet-induced metabolic and vascular dysfunction, and increases adipocyte progenitor cell population in brown adipose tissue

A high-fat diet (HFD) is associated with adipose inflammation, which contributes to key components of metabolic syndrome, including obesity and insulin resistance. The increased visceral adipose tissue mass associated with obesity is the result of hyperplasia and hypertrophy of adipocytes. To investigate the effects of exercise on HFD-induced metabolic disorders, male C57BL/6 mice were divided into four groups: SED (sedentary)-ND (normal diet), EX (exercise)-ND, SED-HFD, and EX-HFD. Exercise was performed on a motorized treadmill at 15 m/min, 40 min/day, and 5 day/wk for 8 wk. Exercise resulted in a decrease in abdominal fat contents and inflammation, improvements in glucose tolerance and insulin resistance, and enhancement of vascular constriction and relaxation responses. Exercise with or without HFD increased putative brown adipocyte progenitor cells in brown adipose tissue compared with groups with the same diet, with an increase in brown adipocyte-specific gene expression in brown and white adipose tissue. Exercise training enhanced in vitro differentiation of the preadipocytes from brown adipose depots into brown adipocytes and enhanced the expression of uncoupling protein 1. These findings suggest that exercise ameliorates high-fat diet-induced metabolic disorders and vascular dysfunction, and increases adipose progenitor cell population in brown adipose tissue, which might thereby contribute to enhanced functional brown adipose.     

Effect of PPAR-delta agonist on the expression of visfatin, adiponectin, and resistin in rat adipose tissue and 3T3-L1 adipocytes

It has been recently reported that activation of PPAR-delta, by specific agonists or genetic manipulation, alleviates dyslipidemia, hyperglycemia, and insulin resistance in animal models of obesity and type 2 diabetes. The purpose of the present study was to determine whether the PPAR-delta agonist has a direct effect on adipokines in visceral adipose tissue of rats and in cultured adipocytes. We examined the expression of visfatin, adiponectin, and resistin mRNA in visceral adipose tissue of Wistar rats fed a high-fat diet and 3T3-L1 adipocytes treated with PPAR-delta agonist (L-165041). Body weight and biochemical measurements were performed. Rats fed a high-fat diet showed a greater increase in body weight than those fed a standard diet (P<0.05), and treatment with L-165041 (10 mg/kg/day) significantly decreased weight gain (P<0.05). The concentration of total cholesterol was lower, and HDL cholesterol was higher in L-165041-treated rats (P<0.05). In the visceral adipose tissue of L-165041-treated rats, visfatin and adiponectin mRNA levels significantly increased compared to those of the untreated rats (P<0.05). However, the expression of resistin decreased in the L-165041-treated rats. Furthermore, in cultured 3T3-L1 adipocytes, the level of visfatin and adiponectin mRNA was up-regulated in response to L-165041 treatment for nine days. By contrast, resistin mRNA levels were down-regulated by L-165041 treatment. The present study provides a novel evidence to suggest that the PPAR-delta agonist has regulatory effects on a variety of adipokines, and these effects might explain some of their metabolic function.     

Low-Dose Bisphenol-A Impairs Adipogenesis and Generates Dysfunctional 3T3-L1 Adipocytes

Environmental endocrine disruptors (EDCs), including bisphenol-A (BPA), have been recently involved in obesity and diabetes by dysregulating adipose tissue function. Our aim was to examine whether prolonged exposure to low doses of BPA could affect adipogenesis and adipocyte metabolic functions. Therefore, 3T3-L1 pre-adipocytes were cultured for three weeks with BPA 1nM to mimic human environmental exposure. We evaluated BPA effect on cell proliferation, differentiation, gene expression and adipocyte metabolic function. BPA significantly increased pre-adipocyte proliferation (p<0.01). In 3T3-L1 adipocytes differentiated in the presence of BPA, the expression of Peroxisome proliferator-activated receptor gamma (PPARγ), Fatty Acid Binding Protein 4/Adipocyte Protein 2 (FABP4/AP2) and CCAAT/enhancer binding protein (C/EBPα) was increased by 3.5, 1.5 and 3 folds, respectively. Mature adipocytes also showed a significant increase in lipid accumulation (p<0.05) and alterations of insulin action, with significant reduction in insulin-stimulated glucose utilization (p<0.001). Moreover, in mature adipocytes, mRNA levels of Leptin, interleukin-6 (IL6) and interferon-γ (IFNγ) were significantly increased (p<0.05). In conclusion, BPA prolonged exposure at low doses, consistent with those found in the environment, may affect adipocyte differentiation program, enhancing pre-adipocyte proliferation and anticipating the expression of the master genes involved in lipid/glucose metabolism. The resulting adipocytes are hypertrophic, with impaired insulin signaling, reduced glucose utilization and increased pro-inflammatory cytokine expression. Thus, these data supported the hypothesis that BPA exposure, during critical stages of adipose tissue development, may cause adipocyte metabolic dysfunction and inflammation, thereby increasing the risk of developing obesity-related diseases.     

Cannabinoid Receptor Type 1 Protects against Age- Related Osteoporosis by Regulating Osteoblast and Adipocyte Differentiation in Marrow Stromal Cells

Age-related osteoporosis is characterized by reduced bone formation and accumulation of fat in the bone marrow compartment. Here, we report that the type 1 cannabinoid receptor (CB1) regulates this process. Mice with CB1 deficiency (CB1^−/−) had increased peak bone mass due to reduced bone resorption, but developed age-related osteoporosis with reduced bone formation and accumulation of adipocytes in the bone marrow space. Marrow stromal cells from CB1^−/− mice had an enhanced capacity for adipocyte differentiation, a reduced capacity for osteoblast differentiation, and increased expression of phosphorylated CREB (pCREB) and PPARγ. Pharmacological blockade of CB1 receptors stimulated adipocyte differentiation, inhibited osteoblast differentiation, and increased cAMP and pCREB in osteoblast and adipocyte precursors. The CB1 receptor is therefore unique in that it regulates peak bone mass through an effect on osteoclast activity, but protects against age-related bone loss by regulating adipocyte and osteoblast differentiation of bone marrow stromal cells.     

Latexin deficiency attenuates adipocyte differentiation and protects mice against obesity and metabolic disorders induced by high-fat diet

Obesity is a risk factor for many chronic diseases, and is associated with increased incidence rate of type 2 diabetes, hypertension, dyslipidemia and cardiovascular diseases. Adipocyte differentiation play critical role during development of obesity. Latexin (LXN), a mammalian carboxypeptidase inhibitor, plays important role in the proliferation and differentiation of stem cells, and highlights as a differentiation-associated gene that was significantly downregulated in prostate stem cells and whose expression increases through differentiation. However, it is unclear whether LXN is involved in adipocyte differentiation. The aim of this study was to evaluate the role of LXN on adipocyte differentiation, as well as its effects on high fat-induced obesity and metabolic disorders. In this study, we determine the expression of LXN in adipose tissue of lean and fat mice by Western blot, qPCR and immunohistochemistry. We found that LXN in fat tissues was continuous increased during the development of diet-induced obesity. We fed wild-type (WT) and LXN^−/−mice with high-fat diet (HFD) to study the effects of LXN on obesity and related metabolic functions. We found that mice deficient in LXN showed resistance against high-fat diet (HFD)-induced obesity, glucose tolerance, insulin tolerance and hepatic steatosis. In vitro studies indicated that LXN was highly induced during adipocyte differentiation, and positively regulated adipocyte differentiation and adipogenesis in 3T3-L1 cells and primary preadipocytes. Functional analysis revealed that the expression of LXN was positively regulated by mTOR/RXR/PPARɤ signaling pathway during the differentiation of adipocytes, while LXN deletion decreased the protein level of PPARɤ in adipocyte through enhancing FABP4 mediated ubiquitination, which led to impaired adipocyte differentiation and lipogenesis. Collectively, our data provide evidence that LXN is a key positive regulator of adipocyte differentiation, and therapeutics targeting LXN could be effective in preventing obesity and its associated disorders in clinical settings.Subject terms: Metabolic disorders, Mechanisms of disease     

Cyclin-dependent kinase inhibitor, p21WAF1/CIP1, is involved in adipocyte differentiation and hypertrophy, linking to obesity, and insulin resistance

Both adipocyte hyperplasia and hypertrophy are determinant factors for adipocyte differentiation during the development of obesity. p21(WAF1/CIP1), a cyclin-dependent kinase inhibitor, is induced during adipocyte differentiation; however, its precise contribution to this process is unknown. Using both in vitro and in vivo systems, we show that p21 is crucial for maintaining adipocyte hypertrophy and obesity-induced insulin resistance. The absence of p21 in 3T3-L1 fibroblasts by RNA-mediated interference knockdown or in embryonic fibroblasts from p21(-/-) mice impaired adipocyte differentiation, resulting in smaller adipocytes. Despite normal adipose tissue mass on a normal diet, p21(-/-) mice fed high energy diets had reduced adipose tissue mass and adipocyte size accompanied by a marked improvement in insulin sensitivity. Knockdown of p21 in enlarged epididymal fat of diet-induced obese mice and also in fully differentiated 3T3-L1 adipocytes caused vigorous apoptosis by activating p53. Thus, p21 is involved in both adipocyte differentiation and in protecting hypertrophied adipocytes against apoptosis. Via both of these mechanisms, p21 promotes adipose tissue expansion during high fat diet feeding, leading to increased downstream pathophysiological consequences such as insulin resistance.     

The chemical chaperone 4-phenylbutyrate inhibits adipogenesis by modulating the unfolded protein response

Recent studies have shown a link between obesity and endoplasmic reticulum (ER) stress. Perturbations in ER homeostasis cause ER stress and activation of the unfolded protein response (UPR). Adipocyte differentiation contributes to weight gain, and we have shown that markers of ER stress/UPR activation, including GRP78, phospho-eIF2α, and spliced XBP1, are upregulated during adipogenesis. Given these findings, the objective of this study was to determine whether attenuation of UPR activation by the chemical chaperone 4-phenylbutyrate (4-PBA) inhibits adipogenesis. Exposure of 3T3-L1 preadipocytes to 4-PBA in the presence of differentiation media decreased expression of ER stress markers. Concomitant with the suppression of UPR activation, 4-PBA resulted in attenuation of adipogenesis as measured by lipid accumulation and adiponectin secretion. Consistent with these in vitro findings, female C57BL/6 mice fed a high-fat diet supplemented with 4-PBA showed a significant reduction in weight gain and had reduced fat pad mass, as compared with the high-fat diet alone group. Furthermore, 4-PBA supplementation decreased GRP78 expression in the adipose tissue and lowered plasma triglyceride, glucose, leptin, and adiponectin levels without altering food intake. Taken together, these results suggest that UPR activation contributes to adipogenesis and that blocking its activation with 4-PBA prevents adipocyte differentiation and weight gain in mice.     

Up-regulation of adipogenin, an adipocyte plasma transmembrane protein, during adipogenesis

Until now, the various proteins highly expressed in adipose tissues have been identified and characterized by traditional gene cloning techniques. However, methods of computer analysis have been developed to compare the levels of expression among various tissues, and genes whose expression levels differ significantly between tissues have been found. Among these genes, we report on the possible function of a new adipose-specific gene, showed higher expression in adipose tissue through ‘Search Expression’ on Genome Institute of Norvartis Research Foundation (GNF) SymAtlas v0.8.0. This database has generated and analyzed gene expression of each gene in diverse samples of normal tissues, organs, and cell lines. This newly discovered gene product was named adipogenin because of its role in stimulating adipocyte differentiation and development. Adipogenin mRNA was highly expressed in four different fat depots, and exclusively expressed in adipocytes isolated from adipose tissues. The level of adipogenin mRNA was up-regulated in the subcutaneous and visceral adipose tissues of mice fed a high-fat diet compared to those on the control diet. The expression of adipogenin mRNA is dramatically elevated during adipocyte differentiation of 3T3-L1 cells. Troglitazone, which up-regulated peroxisome proliferators-activated receptor γ2 (PPAR-γ2) expression, increased adipogenin mRNA expression, although this gene was down-regulated by retinoic acid. Confocal image analyses of green-fluorescent protein-adipogenin (pEGFP-adipogenin) transiently expressed in 3T3-L1 adipocytes showed that adipogenin was strictly localized to membranes and was absent from the cytosol. Moreover, small interfering RNA (siRNA) mediated a reduction of adipogenin mRNA in 3T3-L1 cells and blocked the process of adipocyte differentiation. These results indicate that adipogenin, an adipocyte-specific membrane protein, may be involved with adipogenesis, as one of the regulators of adipose tissue development.Yeon-Hee Hong and Daisuke Hishikawa contributed equally to this work     

抗阻运动对高脂饮食诱导的肥胖大鼠脂肪组织自噬和炎症因子的影响

为探讨运动对肥胖患者自噬活性和内脏脂肪组织炎症反应的影响,本研究将60只肥胖小鼠随机分为高脂饮食组(B)、正常饮食组(C)、正常饮食加耐力运动干预组(D)、正常饮食加耐力运动干预组(E)。D组和E组分别进行10周的耐力和抗阻运动,然后用RT-PCR检测自噬、炎症的基因和蛋白表达。结果显示,三个干预组的Lee指数和BFI均显著降低,2个运动组的Lee指数和BFI均显著降低,但差异无显著性;D组和E组Beclin 1表达较C组显著降低,p62表达明显升高;与C组相比,D组p62显著升高,E组无明显升高;与D组相比,E组Beclin 1基因表达增加,p62蛋白表达降低;与C组相比,D组和E组IL-6和IL-0蛋白表达均显著升高;10周不同运动干预对大鼠减脂效果无差异。运动后内脏脂肪组织的自噬活性受到抑制,尤其是无氧运动;肥胖患者运动干预前后内脏脂肪组织自噬和炎症的变化趋势一致,其中IL-10的变化最为明显。     

Physical exercise mitigates high-fat diet-induced adiposopathy and related endocrine alterations in an animal model of obesity

The dysregulation of adipokine secretion owing to adiposopathy can contribute to the pathogenesis of obesity-related disorders. Being that exercise is an advised strategy against obesity-induced adiposopathy, we aimed to analyze the role of physical exercise as a preventive and therapeutic strategy against high-fat diet (HFD)-induced adipokine and ghrelin alterations. Rats were pair-fed the Lieber De Carli standard diet (S, 35 Kcal% fat) or HFD (71 Kcal% fat) over 17 weeks. Animals were assigned into four groups as follows: standard diet sedentary (SS), standard diet voluntary physical activity (SVPA), high-fat diet sedentary (HS), and high-fat diet voluntary physical activity (HVPA). After 9 weeks of dietary treatment, half of the SS and HS animals were submitted to an 8-week endurance training program, standard diet endurance training (SET), and high-fat-diet endurance training (HET) groups, maintaining the respective diets. Although there were no changes in body weight, HFD increased visceral adiposity, percentage of large adipocytes, hypoxia inducible factor (HIF)-1α, and leptin contents in epididymal adipose tissue (eWAT) and decreased plasma content of adiponectin (AdipQ). Both VPA and ET decreased visceral adiposity and percentage of large adipocytes in HFD-fed animals, but ET also increased the percentage of small- to medium-sized adipocytes. VPA increased plasma growth hormone secretagogue receptor (GHS-R) and decreased leptin protein in HVPA group. ET decreased plasma insulin and leptin levels and eWAT HIF-1α and leptin expression in HET group. Moreover, ET improved insulin sensitivity, plasma high molecular weight, and AdipQ and ghrelin levels and increased eWAT and GHS-R expression. Our data suggest that exercise, particularly ET, reverted adiposopathy and related endocrine alterations induced by an isocaloric HFD pair-fed diet.     

Activation of peroxisome proliferator-activated receptor-alpha stimulates both differentiation and fatty acid oxidation in adipocytes

Peroxisome proliferator-activated receptor-α (PPARα) is a dietary lipid sensor, whose activation results in hypolipidemic effects. In this study, we investigated whether PPARα activation affects energy metabolism in white adipose tissue (WAT). Activation of PPARα by its agonist (bezafibrate) markedly reduced adiposity in KK mice fed a high-fat diet. In 3T3-L1 adipocytes, addition of GW7647, a highly specific PPARα agonist, during adipocyte differentiation enhanced glycerol-3-phosphate dehydrogenase activity, insulin-stimulated glucose uptake, and adipogenic gene expression. However, triglyceride accumulation was not increased by PPARα activation. PPARα activation induced expression of target genes involved in FA oxidation and stimulated FA oxidation. In WAT of KK mice treated with bezafibrate, both adipogenic and FA oxidation-related genes were significantly upregulated. These changes in mRNA expression were not observed in PPARα-deficient mice. Bezafibrate treatment enhanced FA oxidation in isolated adipocytes, suppressing adipocyte hypertrophy. Chromatin immunoprecipitation (ChIP) assay revealed that PPARα was recruited to promoter regions of both adipogenic and FA oxidation-related genes in the presence of GW7647 in 3T3-L1 adipocytes. These findings indicate that the activation of PPARα affects energy metabolism in adipocytes, and PPARα activation in WAT may contribute to the clinical effects of fibrate drugs.     

Role of MAPK phosphatase-1 in the induction of monocyte chemoattractant protein-1 during the course of adipocyte hypertrophy

Monocyte chemoattractant protein-1 (MCP-1), an important chemokine whose expression is increased during the course of obesity, plays a role in macrophage infiltration into obese adipose tissue. This study was designed to elucidate the role of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) in the induction of MCP-1 during the course of adipocyte hypertrophy. We examined the time course of MKP-1 and MCP-1 mRNA expression and extracellular signal-regulated kinase (ERK) phosphorylation in the adipose tissue from mice rendered mildly obese by a short term high fat diet. We also studied the role of MKP-1 in the induction of MCP-1 in 3T3-L1 adipocytes during the course of adipocyte hypertrophy. MCP-1 mRNA expression was increased, followed by ERK activation and down-regulation of MKP-1, an inducible dual specificity phosphatase to inactivate ERK, in the adipose tissue at the early stage of obesity induced by a short term high fat diet, when macrophages are not infiltrated. Down-regulation of MKP-1 preceded ERK activation and increased production of MCP-1 in 3T3-L1 adipocytes in vitro during the course of adipocyte hypertrophy. Adenovirus-mediated restoration of MKP-1 in hypertrophied 3T3-L1 adipocytes reduced the otherwise increased ERK phosphorylation, thereby leading to the significant reduction of MCP-1 mRNA expression. This study provides evidence that the down-regulation of MKP-1 is critical for increased production of MCP-1 during the course of adipocyte hypertrophy.     

Cyclooxygenase-2 deficiency attenuates adipose tissue differentiation and inflammation in mice

Obesity is associated with a variety of disorders and is a significant health problem in developed countries. One factor controlling the level of adiposity is the differentiation of cells into adipocytes. Adipocyte differentiation requires expression of peroxisome proliferator-activated receptor γ (PPARγ), which is activated by ligands to regulate expression of genes involved in adipocyte differentiation. Although 15-deoxy-Δ(12,14)-prostaglandin (PG) J(2) (15d-PGJ(2)) has long been known to be a potent activator of PPARγ, the importance of its synthesis in adipose tissue in vivo is not clear. The current study utilized mice deficient in cyclooxygenase-2 (COX-2) to examine the role of COX-2-derived PGs as in vivo modulators of adiposity. As compared with strain- and age-matched wild-type controls, the genetic deficiency of COX-2 resulted in a significant reduction in total body weight and percent body fat. Although there were no significant differences in food consumption between groups, COX-2-deficient mice showed increased metabolic activity. Epididymal adipose tissue from wild-type mice produced a significantly greater level of 15d-PGJ(2), as compared with adipose tissue isolated from mice deficient in COX-2. Furthermore, production of the precursor required for 15d-PGJ(2) formation, PGD(2), was also significantly reduced in COX-2-deficient adipose tissue. The expression of markers for differentiated adipocytes was significantly reduced in adipose tissue from COX-2-deficient mice, whereas preadipocyte marker expression was increased. Macrophage-dependent inflammation was also significantly reduced in adipose tissue of COX-2-deficient mice. These findings suggest that reduced adiposity in COX-2-deficient mice results from attenuated PPARγ ligand production and adipocyte differentiation.     

Body fat-lowering effect of conjugated linoleic acid is not due to increased lipolysis

The ability of conjugated linoleic acid (CLA) to reduce adiposity may be due to changes in energy expenditure and/or direct effects on adipocyte lipid metabolism. The aim of the present work was to analyse if CLA supplementation modifies lipolytic activity in adipose tissue from hamsters fed on high-fat diet. Hamsters were divided into two groups and fed on diets supplemented with either 0.5% linoleic acid (control) or 0.5% trans-10,cis-12 CLA. After 6 weeks, animals were fasted overnight and adipose tissues were dissected and weighed. Adipocytes were isolated by collagenase digestion and incubated in Krebs-Ringer bicarbonate buffer with or without several agents acting at different levels of the lipolytic cascade. Adipocyte diameters were measured by microscopy. Adipose tissue DNA content was assessed by spectrophotometry. Animals fed on CLA diet showed significantly reduced adipose tissue mass. No differences between both groups was found for basal lipolysis, lipolytic effects of isoproterenol, forskolin, dibutyryl-cAMP and isobutylmethylxanthine, and pD2 for isoproterenol. A similar total DNA amount was found in adipose tissue of both groups, showing that CLA diet had no effect on total cell number per fat pad. Although DNA content per gram tissue, an indirect reverse index of cell size, was significantly increased in CLA fed hamsters, microscopy did not reveal differences in medium mature adipocyte diameter, nor in cell size distribution between both groups. These results suggest that adipose tissue size reduction induced by trans-10,cis-12 CLA intake is not due to changes in lipolysis. Reduced preadipocyte differentiation into mature adipocytes may account for this fat-lowering effect.     

Reducing selenoprotein P expression suppresses adipocyte differentiation as a result of increased preadipocyte inflammation

Oxidative stress and low-grade inflammation have been implicated in obesity and insulin resistance. As a selenium transporter, ubiquitously expressed selenoprotein P (SeP) is known to play a role in the regulation of antioxidant enzyme activity. However, SeP expression and regulation in adipose tissue in obesity and its role in inflammation and adipocyte biology remain unexplored. In this study, we examined Sepp1 gene expression and regulation in adipose tissue of obese rodents and characterized the role of Sepp1 in adipose inflammation and adipogenesis in 3T3-L1 adipocytes. We found that Sepp1 gene expression was significantly reduced in adipose tissue of ob/ob and high-fat diet-induced obese mice as well as in primary adipose cells isolated from Zucker obese rats. Rosiglitazone administration increased SeP protein expression in adipose tissue of obese mice. Treatment of either TNFα or H(2)O(2) significantly reduced Sepp1 gene expression in a time- and dose-dependent manner in 3T3-L1 adipocytes. Interestingly, Sepp1 gene silencing resulted in the reduction in glutathione peroxidase activity and the upregulation of inflammatory cytokines MCP-1 and IL-6 in preadipocytes, leading to the inhibition of adipogenesis and adipokine and lipogenic gene expression. Most strikingly, coculturing Sepp1 KD cells resulted in a marked inhibition of normal 3T3-L1 adipocyte differentiation. We conclude that SeP has an important role in adipocyte differentiation via modulating oxidative stress and inflammatory response.     

Antiobesity effects of coumestrol through expansion and activation of brown adipose tissue metabolism

Coumestrol is a dietary phytoestrogen with estrogen-mimicking characteristics. This study investigated the molecular mechanisms of antiobesity effects of coumestrol. Two weeks of coumestrol treatment reduced body weight and improved glucose tolerance of high-fat diet (HFD)-fed mice. Notably, coumestrol treatment reduced adiposity but expanded brown adipose tissue mass. In addition, coumestrol treatment induced up-regulation of brown adipocyte markers and lipolytic gene expression in adipose tissue. Mechanistically, coumestrol induced an increase in mitochondrial contents of brown adipose tissue, which was associated with up-regulation of adenosine monophosphate-activated protein kinase and sirtuin 1. In vitro knockdown of estrogen receptor 1 inhibited the effect of coumestrol on brown adipogenic marker expression, increase in mitochondrial contents and oxygen consumption rate in brown adipocytes. Furthermore, lineage tracing of platelet-derived growth factor receptor A-positive (PDGFRA+) adipocyte progenitors confirmed increased levels of de novo brown adipogenesis from PDGFRA+ cells by coumestrol treatment. In conclusion, our results indicate that coumestrol has antiobesity effects through the expansion and activation of brown adipose tissue metabolism.