Adipogenesis In Preadipocytes Research Articles

Deficiency of FcϵR1 Increases Body Weight Gain but Improves Glucose Tolerance in Diet-Induced Obese Mice.

Prior studies demonstrated increased plasma IgE in diabetic patients, but the direct participation of IgE in diabetes or obesity remains unknown. This study found that plasma IgE levels correlated inversely with body weight, body mass index, and body fat mass among a population of randomly selected obese women. IgE receptor FcϵR1-deficient (Fcer1a(-/-)) mice and diet-induced obesity (DIO) mice demonstrated that FcϵR1 deficiency in DIO mice increased food intake, reduced energy expenditure, and increased body weight gain but improved glucose tolerance and glucose-induced insulin secretion. White adipose tissue from Fcer1a(-/-) mice showed an increased expression of phospho-AKT, CCAAT/enhancer binding protein-α, peroxisome proliferator-activated receptor-γ, glucose transporter-4 (Glut4), and B-cell lymphoma 2 (Bcl2) but reduced uncoupling protein 1 (UCP1) and phosphorylated c-Jun N-terminal kinase (JNK) expression, tissue macrophage accumulation, and apoptosis, suggesting that IgE reduces adipogenesis and glucose uptake but induces energy expenditure, adipocyte apoptosis, and white adipose tissue inflammation. In 3T3-L1 cells, IgE inhibited the expression of CCAAT/enhancer binding protein-α and peroxisome proliferator-activated receptor-γ, and preadipocyte adipogenesis and induced adipocyte apoptosis. IgE reduced the 3T3-L1 cell expression of Glut4, phospho-AKT, and glucose uptake, which concurred with improved glucose tolerance in Fcer1a(-/-) mice. This study established two novel pathways of IgE in reducing body weight gain in DIO mice by suppressing adipogenesis and inducing adipocyte apoptosis while worsening glucose tolerance by reducing Glut4 expression, glucose uptake, and insulin secretion.

Sam68 Regulates S6K1 Alternative Splicing during Adipogenesis.

The requirement for alternative splicing during adipogenesis is poorly understood. The Sam68 RNA binding protein is a known regulator of alternative splicing, and mice deficient for Sam68 exhibit adipogenesis defects due to defective mTOR signaling. Sam68 null preadipocytes were monitored for alternative splicing imbalances in components of the mTOR signaling pathway. Herein, we report that Sam68 regulates isoform expression of the ribosomal S6 kinase gene (Rps6kb1). Sam68-deficient adipocytes express Rps6kb1-002 and its encoded p31S6K1 protein, in contrast to wild-type adipocytes that do not express this isoform. Sam68 binds an RNA sequence encoded by Rps6kb1 intron 6 and prevents serine/arginine-rich splicing factor 1 (SRSF1)-mediated alternative splicing of Rps6kb1-002, as assessed by cross-linking and immunoprecipitation (CLIP) and minigene assays. Depletion of p31S6K1 with small interfering RNAs (siRNAs) partially restored adipogenesis of Sam68-deficient preadipocytes. The ectopic expression of p31S6K1 in wild-type 3T3-L1 cells resulted in adipogenesis differentiation defects, showing that p31S6K1 is an inhibitor of adipogenesis. Our findings indicate that Sam68 is required to prevent the expression of p31S6K1 in adipocytes for adipogenesis to occur.

In Vitro Effects of Bisphenol A β-D-Glucuronide (BPA-G) on Adipogenesis in Human and Murine Preadipocytes.

BackgroundExposure to common environmental substances, such as bisphenol A (BPA), has been associated with a number of negative health outcomes. In vivo, BPA is rapidly converted to its predominant metabolite, BPA-glucuronide (BPA-G), which has long been believed to be biologically inactive because it lacks estrogenic activity. However, the effects of BPA-G on cellular metabolism have not been characterized. In the present study we examined the effect of BPA-G on adipogenesis.MethodsThe effect of BPA-G on the differentiation of human and 3T3L1 murine preadipocytes was evaluated in vitro by quantifying lipid accumulation and the expression of adipogenic markers.ResultsTreatment of 3T3L1 preadipocytes with 10 μM BPA-G induced a significant increase in lipid accumulation, mRNA expression of the adipogenic markers sterol regulatory element binding factor 1 (SREBF1) and lipoprotein lipase (LPL), and protein levels of LPL, aP2, and adipsin. Treatment of primary human preadipocytes with BPA-G also induced adipogenesis as determined by aP2 levels. Co-treatment of cells with the estrogen receptor (ER) antagonist fulvestrant (ICI) significantly inhibited the BPA-G–induced increase in LPL and aP2 levels, whereas treatment with ICI alone had no effect. Moreover, BPA-G did not display any significant estrogenic activity.ConclusionsTo our knowledge, this study is the first to report that BPA-G induces adipocyte differentiation and is not simply an inactive metabolite. The fact that BPA-G induced adipogenesis and was inhibited by an ER antagonist yet showed no estrogenic activity suggests that it has no classical ER transcriptional activation function and acts through a pathway that remains to be determined.CitationBoucher JG, Boudreau A, Ahmed S, Atlas E. 2015. In vitro effects of bisphenol A β-D-glucuronide (BPA-G) on adipogenesis in human and murine preadipocytes. Environ Health Perspect 123:1287–1293; http://dx.doi.org/10.1289/ehp.1409143

Chronic Activation of Pattern Recognition Receptors Suppresses Brown Adipogenesis of Multipotent Mesodermal Stem Cells and Brown Preadipocytes

Brown adipose tissue (BAT) holds promise to combat obesity through energy‐spending, non‐shivering thermogenesis. Understanding of the regulation of BAT development can lead to novel strategies to increase BAT mass and function for obesity treatment and prevention. Here, we report the effects of chronic activation of pattern recognition receptors on brown adipogenesis of multipotent mesodermal stem C3H10T1/2 cells and immortalized brown preadipocytes derived from classical interscapular BAT of mice. Activation of NOD1, TLR4, or TLR2 by their respective synthetic ligand suppressed brown marker gene expression and lipid accumulation during differentiation of brown‐like adipocytes of C3H10T1/2. Surprisingly, activation of the PRR only during the commitment was sufficient to suppress the differentiation. PRR activation suppressed PGC‐1alpha mRNA, but induced PRDM16 mRNA at the commitment. Consistently, PRR activation suppressed the differentiation of immortalized brown preadipocytes. Activation of PRR induced NF‐κB activation in both cell types, which correlated with their abilities to suppress PPARgamma transactivation, a critical event for brown adipogenesis. Taken together, our results demonstrate that chronic PRR activation suppressed brown adipogenesis of multipotent mesodermal stem cells and brown preadipocytes, possibly through suppression of PPARgamma transactivation. The results suggest that anti‐ inflammatory therapies targeting PRRs may be beneficial for the BAT development.

Increased Levels of Heme‐Oxygenase‐1 Rescues Fructose‐Mediated Adipocyte Dysfunction

Obesity is an epidemic that is becoming increasingly more prevalent, particularly in Western societies, and is associated with an increase in oxidative stress. Unregulated fructose metabolism contributes to obesity by increasing reactive oxygen species (ROS). The aim of this study was to examine whether fructose and uric acid modulate adipogenesis in murine preadipocytes. We also hypothesize that an increase in HO‐1 will decrease ROS and adipocyte hypertrophy. Fructose (5 μM ‐ 1000 μM) and uric acid (10 mg/mL, ‐ 100 mg/mL) or apocynin (50‐500 mM) or allopurinol (550‐100 mM) were added to preadipocytes both in the presence and absence of cobalt protoporphyrin (CoPP), a known HO‐1 inducer. Fructose and uric acid decreased HO‐1 and Wnt10b expression and increased the expression of the adipogenic markers PPARγ, PEG‐1/Mest, and lipid accumulation. An increase in HO‐1 gene expression and HO activity decreased fructose and uric acid mediated lipid deposition and inflammatory cytokine levels, (IL‐1, IL‐6) and the expression of genes of the canonical Wnt signaling cascade (p<0.05). Preadipocytes treated with allopurinol and apocynin had a decreased number of large lipid droplets and ROS. These novel findings demonstrate that increased levels of HO‐1 appear crucial in modulating the phenotype of adipocytes exposed to both fructose and uric acid, in expressing canonical downstream signaling proteins, and in suppressing Peg‐1/Mest proteins, markers of adipocyte hyperplasia and inflammation. Furthermore, this data offers new insights into potential therapies by which targeting the production and/or downstream signaling of uric acid can curtail adipogenesis. Support NIH, HL‐55601, HL34300, BrickStreet Foundation (N.G.A.)

Dibenzoylmethane exerts metabolic activity through regulation of AMP-activated protein kinase (AMPK)-mediated glucose uptake and adipogenesis pathways.

Dibenzoylmethane (DBM) has been shown to exert a variety of beneficial effects on human health. However, the mechanism of action is poorly understood. In this study, DBM increased phosphorylation of AMP-activated protein kinase (AMPK) and stimulated glucose uptake in a skeletal muscle cell line. Both knockdown of AMPK with siRNA and inhibition with AMPK inhibitor blocked DBM-induced glucose uptake. DBM increased the concentration of intracellular calcium and glucose uptake due to DBM was abolished by STO-609 (a calcium/calmodulin-dependent protein kinase inhibitor). DBM stimulated phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), which was blocked by pretreatment with compound C, an AMPK inhibitor. The expression of glucose transporter type 4 (GLUT4) was increased by DBM. The translocation of GLUT4 to the plasma membrane was also increased by DBM in AMPK dependently. In addition, DBM suppressed weight gain and prevented fat accumulation in the liver and abdomen in mice fed a high-fat diet. In pre-adipocyte cells, DBM decreased the activity of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of fatty acid synthesis. Expression of the adipogenic gene, fatty acid synthase (FAS), was suppressed by DBM in an AMPK-dependent manner. These results showed that the beneficial metabolic effects of DBM might be due to regulation of glucose uptake via AMPK in skeletal muscle and inhibition of adipogenesis in pre-adipocytes.

PU.1 antisense lncRNA against its mRNA translation promotes adipogenesis in porcine preadipocytes.

Antisense long non-coding RNAs (AS lncRNAs) play important roles in refined regulation of animal gene expression. However, their functions and molecular mechanisms for domestic animal adipogenesis are largely unknown. Here, we found a novel AS lncRNA transcribed from the porcine PU.1 gene (also known as SPI1) by strand-specific RT-PCR. Results showed that PU.1 AS lncRNA was expressed and generally lower than the level of PU.1 mRNA in porcine subcutaneous adipose, heart, liver, spleen, lympha, skeletal muscle and kidney tissues. We further found that the levels of PU.1 mRNA and PU.1 protein were significantly lower in subcutaneous and intermuscular adipose than in mesenteric and greater omentum adipose, whereas the levels of PU.1 AS lncRNA showed no difference in porcine adipose tissues from four different parts of the body. During porcine adipogenesis, levels of PU.1 mRNA increased at day 2 and then gradually decreased. Meanwhile, PU.1 AS lncRNA exhibited an expression trend similar to PU.1 mRNA but sharply decreased after day 2. Interestingly, PU.1 protein level rose during differentiation. In addition, at day 6 after differentiation, knockdown of endogenous PU.1 promoted adipogenesis, whereas knockdown of endogenous PU.1 AS lncRNA had the opposite effect. Moreover, peroxisome proliferator-activated receptor gamma (PPARG) and fatty acid synthase (FASN) were significantly upregulated in the PU.1 shRNA treatment group (P < 0.05), whereas they were downregulated in the PU.1 AS shRNA treatment group (P < 0.05). Adipose triglyceride lipase [ATGL; also known as patatin-like phospholipase domain containing 2 (PNPLA2)] and hormone-sensitive lipase [HSL; also known as lipase, hormone-sensitive (LIPE)] contrasted with PPARG and FASN. Finally, the PU.1 mRNA/PU.1 AS lncRNA duplex was detected by an endogenous ribonuclease protection assay combined with RT-PCR. Based on the above results, we suggest that PU.1 AS lncRNA (vs. its mRNA translation) promotes adipogenesis through the formation of a sense-antisense RNA duplex with PU.1 mRNA.

Transcriptome analysis of hen preadipocytes treated with an adipogenic cocktail (DMIOA) with or without 20(S)-hydroxylcholesterol.

Background20(S)-hydroxycholesterol (20(S)) potentially reduces adipogenesis in mammalian cells. The role of this oxysterol and molecular mechanisms underlying the adipogenesis of preadipocytes from laying hens have not been investigated. This study was conducted to 1. Analyze genes differentially expressed between preadipocytes treated with an adipogenic cocktail (DMIOA) containing 500 nM dexamethasone, 0.5 mM 3-isobutyl-1-methylxanthine, 20 μg/mL insulin and 300 μM oleic acid (OA) and control cells and 2. Analyze genes differentially expressed between preadipocytes treated with DMIOA and those treated with DMIOA + 20(S) using Affymetrix GeneChip® Chicken Genome Arrays.ResultsIn experiment one, where we compared the gene expression profile of non-treated (control) cells with those treated with DMIOA, out of 1,221 differentially expressed genes, 755 were over-expressed in control cells, and 466 were over-expressed in cells treated with DMIOA. In experiment two, where we compared the gene expression profile of DMIOA treated cells with those treated with DMIOA+20(S), out of 212 differentially expressed genes, 90 were over-expressed in cells treated with DMIOA, and 122 were over-expressed in those treated with DMIOA+20(S).Genes over-expressed in control cells compared to those treated with DMIOA include those involved in cell-to-cell signaling and interaction (IL6, CNN2, ITGB3), cellular assembly and organization (BMP6, IGF1, ACTB), and cell cycle (CD4, 9, 38). Genes over-expressed in DMIOA compared to control cells include those involved in cellular development (ADAM22, ADAMTS9, FIGF), lipid metabolism (FABP3, 4 and 5), and molecular transport (MAP3K8, PDK4, AGTR1). Genes over-expressed in cells treated with DMIOA compared with those treated with DMIOA+20(S) include those involved in lipid metabolism (ENPP2, DHCR7, DHCR24), molecular transport (FADS2, SLC6A2, CD36), and vitamin and mineral metabolism (BCMO1, AACS, AR). Genes over-expressed in cells treated with DMIOA+20(S) compared with those treated with DMIOA include those involved in cellular growth and proliferation (CD44, CDK6, IL1B), cellular development (ADORA2B, ATP6VOD2, TNFAIP3), and cell-to-cell signaling and interaction (VCAM1, SPON2, VLDLR).ConclusionWe identified important adipogenic regulators and key pathways that would help to understand the molecular mechanism of the in vitro adipogenesis in laying hens and demonstrated that 20(S) is capable of suppressing DMIOA-induced adipogenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1231-z) contains supplementary material, which is available to authorized users.

Chronic activation of pattern recognition receptors suppresses brown adipogenesis of multipotent mesodermal stem cells and brown pre-adipocytes.

Brown adipose tissue (BAT) holds promise to combat obesity through energy-spending, non-shivering thermogenesis. Understanding of regulation of BAT development can lead to novel strategies to increase BAT mass and function for obesity treatment and prevention. Here, we report the effects of chronic activation of PRR on brown adipogenesis of multipotent mesodermal stem C3H10T1/2 cells and immortalized brown pre-adipocytes from the classical interscapular BAT of mice. Activation of NOD1, TLR4, or TLR2 by their respective synthetic ligand suppressed brown marker gene expression and lipid accumulation during differentiation of brown-like adipocytes of C3H10T1/2. Activation of the PRR only during the commitment was sufficient to suppress the differentiation. PRR activation suppressed PGC-1α mRNA, but induced PRDM16 mRNA at the commitment. Consistently, PRR activation suppressed the differentiation of immortalized brown pre-adipocytes. Activation of PRR induced NF-κB activation in both cells, which correlated with their abilities to suppress PPARγ transactivation, a critical event for brown adipogenesis. Taken together, our results demonstrate that chronic PRR activation suppressed brown adipogenesis of multipotent mesodermal stem cells and brown pre-adipocytes, possibly through suppression of PPARγ transactivation. The results suggest that anti- inflammatory therapies targeting PRRs may be beneficial for the BAT development.

Dose-dependent effects of neuropeptide Y on the regulation of preadipocyte proliferation and adipocyte lipid synthesis via the PPARγ pathways.

The objective of this study was to investigate the impact of neuropeptide Y (NPY) on preadipocyte proliferation and differentiation. Preadipocytes were incubated with a range of concentrations of NPY (10(-15)M - 10(-7)M). After NPY-induced differentiation, the extent of preadipocyte adipogenesis was evaluated. The expressions levels of related adipocyte markers such as PPARγ, C/EBPα and DLK-1 were examined by real-time PCR (RT-PCR) or western blot analysis. Furthermore, the mitogen-activated protein kinase (MAPK) signaling pathway proteins were also analyzed by western blot. Our results showed that low doses of NPY stimulated preadipocyte viability and proliferation, while high NPY doses inhibited cell viability. At high concentrations of NPY significantly promoted lipid accumulation and increased the size of lipid droplets. DLK-1 mRNA expression was inhibited, but the expression levels of PPARγ and C/EBPα were increased during differentiation with the presence of high concentration of NPY. High-dose NPY also suppressed the phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2 protein. We conclude that NPY has a biphasic effect on preadipocyte proliferation. A high dose inhibits the proliferation of 3T3-L1 cell while promotes adipocyte differentiation, increasing lipid accumulation especially enlarged lipid droplets' size. NPY may lead to a better understanding for drug development to prevent hyperplastic obesity and hypertrophic obesity.

Ethanol extracts of unroasted Coffea canephora robusta beans suppress adipogenesis in preadipocytes and fat accumulation in rats fed a high-fat diet

Anti-adipogenic and anti-obesity effects of a green coffee been extract (GCE) from unroasted Coffea canephora Robusta beans were investigated in vitro and in vivo. Insulin-induced adipogenesis in 3T3-L1 preadipocytes was inhibited by 25.6 and 87.9% following treatment with 100 and 500 µg/mL GCE, respectively. Expression of adipogenesis-specific genes was down-regulated. Body weight gains of C57BL/6 mice fed a high-fat diet (HFD) were suppressed in a concentration-dependent manner using GCE (0.3 or 1% in the diet), exhibiting a marked lower gain in 1% GCE-fed mice than in normal diet-fed animals. Decreases in body fat weights and the size of adipocytes were confirmed. GCE supplementation reduced concentrations of blood lipids and leptin, and attenuated hepatic steatosis. GCE inhibits adipogenesis by modulating cell signaling and improves dietary obesity by reducing lipid accumulation and the size of adipocytes.

PCB126 inhibits adipogenesis of human preadipocytes

Emerging evidence indicates that persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), are involved in the development of diabetes. Dysfunctional adipocytes play a significant role in initiating insulin resistance. Preadipocytes make up a large portion of adipose tissue and are necessary for the generation of functional mature adipocytes through adipogenesis. PCB126 is a dioxin-like PCB and a potent aryl hydrocarbon receptor (AhR) agonist. We hypothesized that PCB126 may be involved in the development of diabetes through disruption of adipogenesis. Using a newly developed human preadipocyte cell line called NPAD (Normal PreADipocytes), we found that exposure of preadipocytes to PCB126 resulted in significant reduction in their subsequent ability to fully differentiate into adipocytes, more so than when the cells were exposed to PCB126 during differentiation. Reduction in differentiation by PCB126 was associated with downregulation of transcript levels of a key adipocyte transcription factor, PPARγ, and late adipocyte differentiation genes. An AhR antagonist, CH223191, blocked this effect. These studies indicate that preadipocytes are particularly sensitive to the effects of PCB126 and suggest that AhR activation inhibits PPARγ transcription and subsequent adipogenesis. Our results validate the NPAD cell line as a useful model for studying the effects of POPs on adipogenesis.

TCF7L2 and Wnt Signalling Positively Regulate Leptin Gene Expression in Adipocytes

Recent genome-wide association studies (GWAS) have revealed that the Wnt signalling pathway effector TCF7L2 is among the most important diabetes risk genes. Intensive explorations on metabolic function of TCF7L2 in pancreas and liver, however, have generated controversial suggestions. As TCF7L2 is also abundantly expressed in adipocytes, we investigated its expression and function in rodent fat tissue and primary adipocytes. We found that TCF7L2 expression in mouse epididymal fat tissue was physiologically upregulated by feeding, and downregulated in db/db mice and Zucker (fa/fa) rats, 2 obese rodent models. In rat primary adipocytes, 1 nM insulin stimulated TCF7L2 and leptin mRNA expression levels, and the stimulation can be attenuated by iCRT14, an inhibitor of β-catenin-responsive transcription. Insulin at the dosage of 100 nM, however, repressed both TCF7L2 and leptin mRNA levels. The canonical Wnt ligand Wnt3a, but not the non-canonical Wnt ligand Wnt11, was shown to stimulate leptin mRNA expression level and leptin gene promoter activity. Although Wnt3a repressed the differentiation of 3T3-L1 cells toward adipocytes, in either fully differentiated or partially differentiated 3T3-L1 cells, Wnt3a significantly stimulated leptin mRNA levels. Together, our observations suggest that adipocytes TCF7L2 level is metabolic regulated. More importantly, Wnt pathway plays a dual function in adipocytes, including the repression of adipogenesis in pre-adipocytes and the stimulation of leptin production in mature adipocytes, in response to nutritional challenge.

Identification of mechanisms of action of bisphenol a-induced human preadipocyte differentiation by transcriptional profiling.

Exposure to the endocrine-disrupting chemical bisphenol A (BPA) is correlated with obesity and adipogenesis of human preadipocytes. However, the mechanism of action of BPA-induced human adipogenesis remains to be determined. Primary human preadipocytes were differentiated in the presence of 50 µM BPA or 1 µM dexamethasone (DEX) for 48 hours. Potential mechanisms of BPA-induced adipogenesis were evaluated using gene expression microarray analysis. Microarray analysis revealed 373 differentially expressed genes following BPA treatment, including upregulation of sterol regulatory element binding factor 1 (SREBF1), a key regulator of lipid metabolism. For DEX-treated preadipocytes, 2167 genes were differentially expressed, including upregulation of the adipogenic marker lipoprotein lipase. Ingenuity Pathway Analysis was used to identify functional annotations of the gene expression changes associated with response to BPA and DEX. BPA exposure was associated with expression changes in the genes involved in triacylglycerol accumulation while DEX was linked to triacylglycerol and fatty acid metabolism. The analysis also revealed enrichment of genes following BPA exposure in the thyroid-receptor/retinoic X receptor (TR/RXR) and mammalian target of rapamycin (mTOR) signaling pathways. Our data suggest that potential mechanisms of action of BPA-induced adipogenesis involve SREBF1, the TR/RXR, and the mTOR pathways.

세포배양 모델을 통한 함초(Salicornia herbacea L.) 물 추출물의 항비만 효과 탐색

As a natural plant ingredients, glasswort (Salicornia herbacea L.) contains various physiological activities, mainly anti-oxidative and anti-diabetic activities. However, only a few studies have been carried out on its anti-adipogenic effect. This study investigated the anti-obesity effects of Salicornia herbacea L. on 3T3-L1 adipocytes. As adipogenesis of preadipocytes to adipocytes involves proliferation and differentiation of cells, we treated three concentrations (125, 250, and 500 μg/mL) of Salicornia herbacea L. water extracts (SLW) in both pre-processing and post-processing stages. When 3T3-L1 adipocytes were differentiated and dyed with Oil Red O, adipocytes size and the value of relative Oil Red O staining were reduced by all concentrations of SLW in post-processing stage. Following adipogenic differentiation, the concentration of tumor necrosis factor-α (TNF-α) in the cell supernatant significantly increased upon treatment with 125 μg/mL of SLW and further rose at concentrations of 250 and 500 μg/mL during post-processing stage. There was no significant difference in glycerol production upon SLW treatment. Leptin production significantly decreased at all SLW concentrations during post-processing stage, whereas peroxisome proliferator activated receptor-γ (PPAR-γ) and adiponectin secretions were significantly enhanced. Overall results showed that SLW might have an anti-adipogenic effect via enhancement of TNF-α production, which causes dedifferentiation and inhibits lipid accumulations in adipocyte. Furthermore, SLW might prevent diabetes and cardiovascular disease, as it reduces leptin secretion and enhances production of both PPAR-γ and adiponectin. However, further research is needed to elucidate the exact mechanism and bioactive compounds of glasswort.

Low abdominal subcutaneous preadipocyte adipogenesis is associated with visceral obesity, visceral adipocyte hypertrophy, and a dysmetabolic state

Subcutaneous adipose tissue expansion through adipogenesis is increasingly recognized as a major determinant of body fat distribution and obesity-related cardiometabolic alterations. Our objective was to assess whether adipogenic rates of cultured human primary preadipocytes from the visceral and subcutaneous compartments relate to visceral obesity and cardiometabolic alterations. We recruited 35 women undergoing gynecological surgery and assessed body fat distribution by CT as well as fasting plasma lipids and glycemia. Fat samples from the greater omentum and abdominal subcutaneous (SC) compartments were used to assess mature adipocyte cell size and establish primary preadipocyte cultures. Differentiation was induced using adipogenic media and adipogenic rates were assessed using Oil Red O (ORO) absorbance/DNA content ratio and glyceraldehyde 3-phosphate dehydrogenase (G3PDH) activity/DNA of differentiated cells. We found a lower adipogenic capacity of omental (OM) preadipocytes than SC preadipocytes originating from the same women (P < 0.05). Whereas only OM cell size was different among groups of low vs high OM adipogenic rate, SC adipogenic rates were clearly related to increased OM cell size and dyslipidemia when women were separated on median value of either ORO/DNA or G3PDH activity/DNA ratios. When matched for BMI, women with low SC preadipocyte adipogenic rates had a higher visceral adipose tissue area (P < 0.01), omental adipocyte hypertrophy (P < 0.05), higher VLDL-lipid content (P < 0.01) and higher fasting glycemia (P < 0.05) than those with low SC adipogenic rates. In conclusion, low abdominal subcutaneous preadipocyte differentiation capacity in vitro is associated with visceral obesity, visceral adipocyte hypertrophy, and a dysmetabolic state.

Ivy gourd (Coccinia grandis L. Voigt) root suppresses adipocyte differentiation in 3T3-L1 cells.

BackgroundIvy gourd (Coccinia grandis L. Voigt) is a tropical plant widely distributed throughout Asia, Africa, and the Pacific Islands. The anti-obesity property of this plant has been claimed but still remains to be scientifically proven. We therefore investigated the effects of ivy gourd leaf, stem, and root on adipocyte differentiation by employing cell culture model.MethodsDried roots, stems, and leaves of ivy gourd were separately extracted with ethanol. Each extract was then applied to 3T3-L1 pre-adipocytes upon induction with a mixture of insulin, 3-isobutyl-1-methylxanthine, and dexamethasone, for anti-adipogenesis assay. The active extract was further fractionated by a sequential solvent partitioning method, and the resulting fractions were examined for their abilities to inhibit adipogenesis in 3T3-L1 cells. Differences in the expression of adipogenesis-related genes between the treated and untreated cells were determined from their mRNA and protein levels.ResultsOf the three ivy gourd extracts, the root extract exhibited an anti-adipogenic effect. It significantly reduced intracellular fat accumulation during the early stages of adipocyte differentiation. Together with the suppression of differentiation, expression of the genes encoding PPARγ, C/EBPα, adiponectin, and GLUT4 were down-regulated. Hexane-soluble fraction of the root extract also inhibited adipocyte differentiation and decreased the mRNA levels of various adipogenic genes in the differentiating cells.ConclusionsThis is the first study to demonstrate that ivy gourd root may prevent obesity based mainly on the ability of its active constituent(s) to suppress adipocyte differentiation in vitro. Such an inhibitory effect is mediated by at least down-regulating the expression of PPARγ-the key transcription factor of adipogenesis in pre-adipocytes during their early differentiation processes.

BMP and activin membrane-bound inhibitor (BAMBI) inhibits the adipogenesis of porcine preadipocytes through Wnt/β-catenin signaling pathway

The process of differentiation from preadipocytes to adipocytes contributes to adipose tissue expansion in obesity. Blocking adipogenesis may be conducive to the etiology of obesity-related diseases. BMP and activin membrane-bound inhibitor (BAMBI) is a transmembrane protein, which was identified as a target of β-catenin in colorectal and hepatocellular tumor cells. However, whether BAMBI affects adipogenesis by Wnt/β-catenin signaling remains to be explored. In this study, we distinguish BAMBI as an inhibitor of preadipocytes differentiation. We found that BAMBI was downregulated during preadipocytes differentiation. Knockdown of BAMBI increased adipogenesis and blocked Wnt/β-catenin signaling by repressing β-catenin accumulation. In BAMBI overexpression cells, lipid accumulation was reduced by promoting nuclear translocation of β-catenin. Lithium chloride (LiCl) is an activator of Wnt/β-catenin signaling, which is an inhibitor of glycogen synthetase kinase-3 (GSK-3), maintaining the stability of β-catenin in cytosolic. We showed BAMBI strengthened the anti-adipogenic effects of LiCl. In addition, the results indicated that BAMBI was upregulated by β-catenin. These observations illuminated that BAMBI inhibits adipogenesis by a feedback loop (BAMBI→β-catenin nuclear translocation→BAMBI), which forms with Wnt/β-catenin signaling.

Novel role of nuclear receptor rev-erbα in hepatic stellate cell activation: Potential therapeutic target for liver injury

Hepatic stellate cell (HSC) transdifferentiation from a quiescent, adipocyte-like cell to a highly secretory and contractile myofibroblast-like phenotype contributes to negative pathological consequences, including fibrosis/cirrhosis with portal hypertension (PH). Antiadipogenic mechanisms have been shown to underlie activation of HSCs. We examined the role of heme-sensing nuclear receptor Rev-erbα, a transcriptional repressor involved in metabolic and circadian regulation known to promote adipogenesis in preadipocytes, in HSC transdifferentiation. We discovered that Rev-erbα protein was up-regulated in activated HSCs and injured livers; however, transcriptional repressor activity was not affected by fibrogenic treatments. Surprisingly, increased protein expression was accompanied with increased cytoplasmic accumulation of Rev-erbα, which demonstrated distributions similar to myosin, the major cellular motor protein. Cells overexpressing a cytoplasm-localized Rev-erbα exhibited enhanced contractility. Ectopically expressed Rev-erbα responded to both adipogenic ligand and fibrogenic transforming growth factor beta treatment. Rev-erb ligand SR6452 down-regulated cytoplasmic expression of Rev-erbα, decreased expression of fibrogenic markers and the activated phenotype in HSCs, and ameliorated fibrosis and PH in rodent models. Up-regulation of Rev-erbα is an intrinsic fibrogenic response characterized by cytoplasmic accumulation of the protein in activated HSCs. Cytoplasmic expression of Rev-erbα promotes a contractile phenotype. Rev-erbα acts as a bifunctional regulator promoting either anti- or profibrogenic response, depending on milieu. Rev-erb ligand SR6452 functions by a previously undescribed mechanism, targeting both nuclear activity and cytoplasmic expression of Rev-erbα. Our studies identify Rev-erbα as a novel regulator of HSC transdifferentiation and offers exciting new insights on the therapeutic potential of Rev-erb ligands.

Ramalin suppresses adipocyte differentiation though the MAPKs pathway in 3T3‐L1 preadipocyte (657.10)

Obesity is a main risk factor for several metabolic disorders such as type 2 diabetes, hypertension, and cardiovascular diseases. Obesity is also recognized as a low‐grade chronic inflammation. In the current study, the inhibitory effect of ramalin, isolated from Antarctic lichen, Ramalina terebrata, on adipocyte differentiation in 3T3‐L1 cells was examined. Ramalin attenuated the accumulation of lipid droplets stained with Oil red O in non‐toxic concentration. Western blot assay showed that ramalin remarkably inhibited the level of peroxisome proliferator‐activated receptor γ (PPAR γ) and CCAAT/enhancer‐binding protein β (c/EBP β) as well as CCAAT/enhancer‐binding protein α (c/EBP alpha) in a concentration dependent manner. Real‐time PCR assay revealed that the expression of MDI‐induced adipogenesis related genes (GLUT4, aP2, leptin) was significantly suppressed by ramalin. Our data also showed that ramalin significantly decreased phosphorylation of ERK1/2, p38 and JNK in a concentration‐dependent manner. Results from ELISA assay demonstrated that ramalin reduced the production of IL‐6 and TNF‐α. Taken together, ramalin can be a novel therapeutic candidate for controlling adipogenesis in preadipocytes.