Adipocyte Differentiation In 3T3-L1 Preadipocytes Research Articles

Proanthocyanidins and Phenolic Compounds from the Twigs of Salix chaenomeloides and Their Anti-Lipogenic Effects on 3T3-L1 Preadipocytes.

The present study investigated potential bioactive natural products from the EtOH extract of Salix chaenomeloides twigs using column chromatography, leading to the isolation of six compounds (1-6), which were characterized as two proanthocyanidins, procyanidin B2 (1) and procyanidin B1 (2), and four phenolic compounds, 4-hydroxybenzoic acid β-D-glucosyl ester (3), di-O-methylcrenatin (4), p-coumaric acid glucoside (5), and syringin (6) by the comparison of their NMR spectra with the reported data and high-resolution (HR)-electrospray ionization mass spectroscopy (ESI-MS) analysis. We investigated the potential of six compounds (1-6) to inhibit adipogenesis in 3T3-L1 preadipocytes, which showed that the compounds (1-6) significantly reduced lipid accumulation in 3T3-L1 adipocytes without affecting cell proliferation. Notably, compound 1 demonstrated a remarkable 60% and 90% reduction in lipid levels with 50 and 100 µM treatments, respectively. Oil Red O staining results indicated that compound 1 significantly inhibits the formation of lipid droplets, comparable to the effect of T863, an inhibitor of triglyceride used as a positive control, in adipocytes. Compound 1 had no effect on the regulators PPARγ, C/EBPα, and SREBF1 of adipocyte differentiation in 3T3-L1 preadipocytes, but compound 1 activated the fatty acid oxidation regulator, PPARα, compared to the lipogenic-induced control. It also suppressed fatty acid synthesis by downregulating the expression of fatty acid synthase (FAS). Finally, compound 1 induced the mRNA and protein levels of CPT1A, an initial marker of mitochondrial fatty acid oxidation in 3T3-L1. This finding substantiates the anti-lipogenic and lipolytic effects of procyanidin B2 (1) in 3T3-L1 preadipocytes, emphasizing its pivotal role in modulating obesity-related markers.

Brown Algae Dictyopteris divaricata Attenuates Adipogenesis by Modulating Adipocyte Differentiation and Promoting Lipolysis through Heme Oxygenase-1 Activation in 3T3-L1 Cells.

The present study aims to explore the probable anti-adipogenesis effect of Dictyopteris divaricata (D. divaricata) in 3T3-L1 preadipocytes by regulating heme oxygenase-1 (HO-1). The extract of D. divaricata retarded lipid accretion and decreased triglyceride (TG) content in 3T3-L1 adipocytes but increased free glycerol levels. Treatment with the extract inhibited lipogenesis by inhibiting protein expressions of fatty acid synthase (FAS) and lipoprotein lipase (LPL), whereas lipolysis increased by activating phosphorylation of hormone-sensitive lipase (p-HSL) and AMP-activated protein kinase (p-AMPK). The extract inhibited adipocyte differentiation of 3T3-L1 preadipocytes through down-regulating adipogenic transcription factors, including peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1). This is attributed to the triggering of Wnt/β-catenin signaling. In addition, this study found that treatment with the extract activated HO-1 expression. Pharmacological approaches revealed that treatment with Zinc Protoporphyrin (ZnPP), an HO-1 inhibitor, resulted in an increase in lipid accumulation and a decrease in free glycerol levels. Finally, three adipogenic transcription factors, such as PPARγ, C/EBPα, and SREBP1, restored their expression in the presence of ZnPP. Analysis of chemical constituents revealed that the extract of D. divaricata is rich in 1,4-benzenediol, 7-tetradecenal, fucosterol, and n-hexadecanoic acid, which are known to have multiple pharmacological properties.

Methanol Extract of Mongolian Iris bungei Maxim. Stimulates 3T3-L1 Adipocyte Differentiation.

Iris bungei Maxim. (IB), which is native to China and Mongolia, is used as a traditional medicine for conditions such as inflammation, cancer, and bacterial infections. However, the effects of Iris bungei Maxim. on adipocyte differentiation have not been studied. In the present study, we first demonstrated the molecular mechanisms underlying the adipogenic activity of the methanol extract of Mongolian I. bungei Maxim. (IB). IB significantly enhanced intracellular lipid accumulation and adipocyte differentiation in 3T3-L1 preadipocytes in a concentration-dependent manner. Moreover, IB markedly stimulated the expression of genes related to adipogenesis such as peroxisome proliferator-activated receptor γ, adiponectin, and aP2. In addition, we also observed that IB induces lipogenic genes such as fatty acid synthase, sterol regulatory element binding protein 1c, stearoyl-CoA desaturase, and acetyl-CoA carboxylase. Interestingly IB regulated adipocyte differentiation in both the early and middle stages. Taken together, these adipogenic and lipogenic effects of IB suggest its efficacy for the prevention and/or treatment of type 2 diabetes.

Scopolin Prevents Adipocyte Differentiation in 3T3-L1 Preadipocytes and Weight Gain in an Ovariectomy-Induced Obese Mouse Model.

Obesity is prevalent in modern human societies. We examined the anti-obesity effects of scopolin on adipocyte differentiation in preadipocyte 3T3-L1 cells and weight loss in an ovariectomy (OVX)-induced obese mouse model. Scopolin inhibited adipocyte differentiation and lipid accumulation in the preadipocyte cells by suppressing the transcription of adipogenic-related factors, including adiponectin (Adipoq), peroxisome proliferator-activated receptor gamma (Pparg), lipoprotein lipase (Lpl), perilipin1 (Plin1), fatty acid-binding protein 4 (Fabp4), glucose transporter type 4 (Slc2a4), and CCAAT/enhancer-binding protein alpha (Cebpa). In OVX-induced obese mice, administration of scopolin promoted the reduction of body weight, total fat percentage, liver steatosis, and adipose cell size. In addition, the scopolin-treated OVX mice showed decreased serum levels of leptin and insulin. Taken together, these findings suggest that the use of scopolin prevented adipocyte differentiation and weight gain in vitro and in vivo, indicating that scopolin may be a potential bioactive compound for the treatment and prevention of obesity in humans.

In vitro effects of Triclocarban on adipogenesis in murine preadipocyte and human hepatocyte

Triclocarban (TCC), a widely used antibacterial agent, has aroused considerable public concern due to its potential toxicity. In the current study, we applied targeted metabolite profiling (LC/GC−MS) and untargeted 1H NMR-based metabolomics in combination with biological assays to unveil TCC exposure-induced cellular metabolic responses in murine preadipocyte and human normal hepatocytes. We found that TCC promoted adipocyte differentiation in 3T3L1 preadipocytes, manifested by marked triglyceride (TG) and fatty acids accumulation, which were consistent with significant up-regulation of mRNA levels in the key adipogenic markers Fasn, Srebp1 and Ap2. In human hepatocytes (L02), TCC exposure dose-dependently interfered with the cellular redox state with down-regulated levels of antioxidant reduced-GSH and XBP1 and further induced the accumulation of TG, ceramides and saturated fatty acid (16:0). We also found that TCC exposure triggered unfold protein response (UPR) and endoplasmic reticulum (ER) stress in both cells through activation of ATF4 and ATF6, resulting in toxic lipid accumulation. These findings about lipid metabolism and metabolic responses to TCC exposure in both preadipocytes and hepatocytes provide novel perspectives for revealing the mechanisms of TCC toxicity.

Anti-adipogenic and anti-oxidant effects of a standardised extract of Moro blood oranges (Citrus sinensis (L.) Osbeck) during adipocyte differentiation of 3T3-L1 preadipocytes

Particular features in the pulp of blood oranges are marked levels of anthocyanin, a class of polyphenolic compounds well known to exert numerous health-promoting actions on human wellbeing including anti-obesity effects. In this study, we investigated in vitro, the antioxidant and anti-adipogenic activities of Morosil®, a standardised extract of Moro blood oranges. During adipocyte differentiation, 3T3-L1 cells were treated with concentrations of extract containing 2.5, 5, 10, 25 μM of anthocyanins. After seven days of treatment and differentiation, we measured reactive oxygen species production, non-proteic thiol groups content, adipokine secretion and triglyceride accumulation together with mRNA expression of adipogenic transcription factors such as PPARγ, C/EBPα, SREBP-1c. Furthermore, both ACCα, FAS protein expression and citrate synthase activity were measured. Results show that Morosil® exerts antioxidant and anti-adipogenic activities during adipocyte differentiation of 3T3-L1 pre-adipocytes.

Long non-coding RNA lnc-OAD is required for adipocyte differentiation in 3T3-L1 preadipocytes

Long non-coding RNAs (lncRNAs) have gained extensive attentions due to their significant roles in diverse biological process. However, the potential functions of lncRNAs participation in adipocyte differentiation have not been fully explored. Here we identified a long non-coding RNA called lnc-OAD (lncRNA associated with osteoblast and adipocyte differentiation, transcribed from 1700018A04Rik gene), which modulated 3T3-L1 adipocyte differentiation. Lnc-OAD was up-regulated expression during 3T3-L1 differentiation and stable knockdown of lnc-OAD inhibited adipocyte differentiation in 3T3-L1 cells. Further mechanisms study revealed that silencing of lnc-OAD strongly elevated the protein expression of β-catenin, and then decreased expression of adipocyte master transcription factors PPAR-γ and C/EBPα. The addition of IWR-1 up-regulated the expression of PPAR-γ and C/EBPα and rescued the impairment of adipocyte differentiation caused by lnc-OAD knockdown. Meanwhile, we also found mitotic clonal expansion (MCE) during the early stage of adipocyte differentiation was inhibited in lnc-OAD-knockdown cells. Taken together, our study reveals a novel function of lnc-OAD in modulating adipogenesis via influencing mitotic clonal expansion and regulating WNT/β-catenin signaling pathway.

한국인 여성 및 식품 유래 유산균의 생리적 특성 및 지방분화 억제효과

Obesity is the most common health problem in developed countries and is considered a significant risk factor for many major human diseases. This study aimed to evaluate the inhibitory effect of lactic acid bacteria isolated from the human vagina and shellfish on adipocyte differentiation in 3T3-L1 preadipocytes. The activity of separated 221 strains on pancrease lipase was measured and 15 strains were first screened. The level of adipogenesis of these strains in the 3T3-L1 cells was measured by Oil Red O staining assay. Five strains including Lactobacillus plantarum (2 strains) and L. fermentum (3 strains) showed good adipocyte differentiation inhibitory activity. Also, the selected strains were resistant to bile acid up to 3% and their autoaggregation rates were as high as 50%. These Lactobacillus strains with probiotics potential may be useful for prevention or treatment of obesity, but further in vitro and in vivo studies on these strains are still required.

Antiadipogenic Effects of Loganic Acid in 3T3-L1 Preadipocytes and Ovariectomized Mice.

Obesity is caused by an excess storage of body fat, resulting from a chronic imbalance between energy intake and expenditure. Gentiana lutea L. (GL) root has been reported to reduce lipid accumulation in the aortic wall of diabetic rats. Here, we performed fractionation and isolation of the bioactive constituent(s) that may be responsible for the antiadipogenic effects of the GL root extract. A single compound, loganic acid, was identified as a candidate component in the 30% ethanol extract of GL. Loganic acid treatment significantly decreased the adipocyte differentiation of 3T3-L1 preadipocytes in a dose-dependent manner. The expression of key adipogenesis-related genes such as adiponectin (Adipoq), peroxisome proliferator-activated receptor gamma (Pparg), lipoprotein lipase (Lpl), perilipin1 (Plin1), fatty acid binding protein 4 (Fabp4), glucose transporter type 4 (Slc2a4), CCAAT/enhancer-binding protein alpha (Cebpa), and tumor necrosis factor-alpha (Tnf) were significantly reduced following treatment with loganic acid. In vivo experiments in an ovariectomy-induced obesity mouse model showed that loganic acid (oral administration with 10 and 50 mg/kg/day) significantly inhibited body weight gain, total fat increase, fatty hepatocyte deposition in the liver, and adipocyte enlargement in the abdominal visceral fat tissues. These results suggest that loganic acid in the GL root extract has antiadipogenic effects in vitro and in vivo. Loganic acid may be beneficial for the prevention and treatment of obesity, particularly in menopausal obese women.

Dual Effects of Metformin on Adipogenic Differentiation of 3T3-L1 Preadipocyte in AMPK-Dependent and Independent Manners.

Metformin has been reported to have body weight lowering effects while treating type 2 diabetes. However, limited studies examined the effects of metformin on adipogenesis in vitro, and available data are inconclusive and contradictory. In this study, we examined the effects of a variety of concentrations of metformin on adipocyte differentiation of 3T3-L1 preadipocytes and found metformin exhibits a dual effect on adipogenesis. Metformin at lower concentrations (1.25–2.5 mM) significantly induced adipogenesis while at higher concentrations (5–10 mM) metformin significantly inhibited adipogenesis in 3T3-L1 cells. The biphasic effect of different doses of metformin on adipogenesis was accompanied by increasing or decreasing the expression of adipogenic and lipogenic genes including peroxisome proliferator-activated receptor (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), and fatty acid synthase (FASN) at both messenger RNA (mRNA) and protein levels. Furthermore, only the higher concentrations of metformin induced the phosphorylation of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK), p38, and c-Jun N-terminal kinase (JNK) and reduced the phosphorylation of extracellular regulated protein kinases (ERK) and Akt. Pretreatment with compound C, a specific AMPK inhibitor, significantly countered high concentration of metformin-induced inhibition of adipogenesis. Taken together, these findings demonstrate that the effect of metformin on adipocyte differentiation is biphasic and dose-dependent. Lower concentrations of metformin induce adipogenesis, which could be mediated in an AMPK-independent manner, while higher concentrations of metformin inhibit adipogenesis via AMPK activation.

Methyl dehydroabietate counters high fat diet-induced insulin resistance and hepatic steatosis by modulating peroxisome proliferator-activated receptor signaling in mice

The aim of this study was to investigate the therapeutic effects of methyl dehydroabietate (mDA) on adipocyte differentiation in 3T3-L1 preadipocytes and obesity characteristics induced by high-fat diet (HFD) in mice. Adipocyte differentiation in 3T3-L1 cells was evaluated after 14 days of incubation with mDA. mDA enhanced adipocyte differentiation in 3T3-L1 cells. For the in vivo evaluation, five-week-old male C57BL/6J mice were fed HFD or normal CE-2 diet (control) for eight weeks. During the experimental period, mice were administered mDA (50 mg/kg, p.o.) as an olive oil emulsion (containing 10% ethanol), and body weights were measured weekly. At the end of the experiment, the mice were euthanized after 16 h fasting period, and plasma samples were collected. The liver, kidney, and epididymal adipose tissues were collected and weighed. It significantly decreased body weight, adipose tissue weight, and plasma levels of glucose, insulin, leptin, and pro-inflammatory cytokines compared with that in the HFD group, and markedly reduced the impairment in glucose tolerance in obese mice. Furthermore, mDA reduced HFD-induced adipocyte hypertrophy and the formation of hepatic lipid droplets. Moreover, it induced the expression of proliferator-activated receptor alpha (PPARα) in the liver and PPARγ in the adipose tissues. Our findings demonstrate that mDA reduces obesity-induced glucose and insulin tolerance by inducing PPAR expression.

Novel anti-adipogenic activity of anti-malarial amodiaquine through suppression of PPARγ activity.

Amodiaquine (AQ) was developed as a selective drug against Plasmodium falciparum malaria infection and has received increasing attention as a therapeutic agent for the treatment of rheumatoid arthritis, Parkinson's disease, and cancer due to its anti-inflammatory, anti-proliferative, and autophagic-lysosomal blockade properties. As autophagy activation is involved in promoting adipogenic differentiation, we examined whether anti-autophagic AQ affected adipocyte differentiation of 3T3-L1 pre-adipocytes. AQ dose-dependently and significantly suppressed adipocyte differentiation in conjunction with decreases in lipid droplet formation and expression of adipogenic markers including adiponectin, adipocyte fatty acid-binding protein 2 (aP2), resistin, and leptin. Although peroxisome proliferator-activated receptor γ (PPARγ) decreases by inhibition of autophagy, AQ treatment did not induce PPARγ degradation despite the suppression of autophagolysosomal degradation. Instead, AQ suppressed the PPARγ activity to transcriptionally activate the aP2 gene transcription through the selective prevention of nuclear localization of PPARγ. These results demonstrated the novel anti-adipogenic activity of AQ and identified its underlying mechanism that AQ suppressed adipogenic gene expression and lipid formation by inhibiting nuclear localization of PPARγ in an autophagy-independent manner. AQ is recommended as a safe and effective anti-obesity drug for controlling overweight and obesity.

Ethyl acetate fraction of Eclipta alba: a potential phytopharmaceutical targeting adipocyte differentiation

Natural products have always fascinated mankind for their miraculous properties. Eclipta alba (E. alba), a medicinal herb has long been used in traditional medicine for curing several pathologies. It has been shown to have anti-diabetic effect as well as hepato-protective activity. Here, in order to address metabolic derangements, the study was designed to evaluate the efficacy of E. alba and its fractions in adipogenesis inhibition and dyslipidemia. Of the crude extract and fractions screened, ethyl acetate fraction of E. alba inhibited adipocyte differentiation in 3T3-L1 pre-adipocytes and hMSC derived adipocytes. It inhibited mitotic clonal expansion and caused cell cycle arrest in G1 and S phase as suggested by western blot analysis and flow cytometry. It was also shown to have lipolytic effects. Oral administration of ethyl acetate fraction of E. alba to hamsters unveiled its anti-adipogenic as well as anti-dyslipidemic activity in-vivo. Mass spectrometry analysis of ethyl acetate fraction confirmed the presence of several bioactive components, projecting it as an effective phytopharmaceutical agent. In conclusion, ethyl acetate fraction of E. alba possesses potent anti-adipogenic as well as anti-dyslipidemic activity and could be projected as an herbal formulation towards obesity.

Sulfuretin has therapeutic activity against acquired lymphedema by reducing adipogenesis

Acquired lymphedema is a pathological condition associated with lymphatic dysfunction caused by surgical treatments for cancer. Although global estimates of the prevalence of acquired lymphedema have been rising, there are currently no effective therapeutics available. Since adipose tissue accumulation is a clinical hallmark of lymphedema, we hypothesized that regulation of adipogenesis in lymphedematous tissue could be used as a therapeutic intervention against lymphedema. Toward this, we investigated the possibility of anti-adipogenic 30% ethanol Rhus verniciflua Stokes (RVS) extract as a potential lymphedema treatment. Oral administration of RVS extract ameliorated volumetric symptoms of lymphedema in a mouse model. RVS administration also reduced adipose tissue accumulation in lymphedematous tissue and downregulated expression of adipocyte markers, including Pparγ and Fabp4. Sulfuretin was identified as a major bioactive compound in the 30% ethanol RVS extract in liquid chromatography-mass spectrometry analysis. Similar to the activities of RVS, sulfuretin inhibited adipocyte differentiation in 3T3-L1 preadipocytes. Moreover, treatment with sulfuretin on lymphedema-induced mice reduced lymphedema volume, decreased the expression of adipogenic markers, but induced the expression of markers associated with lymphangiogenesis. Taken together, our data raise the possibility that sulfuretin might be used in therapeutic interventions against acquired lymphedema.

Effects of Flavonoids and Triterpene Analogues from Leaves of Eleutherococcus sieboldianus (Makino) Koidz. 'Himeukogi' in 3T3-L1 Preadipocytes.

Eleutherococcus sieboldianus (Makino) Koidz. is a local product from the area in and around Yonezawa City in Yamagata Prefecture, Japan. It has been used as a medicinal plant for a long time. We isolated and identified four types of flavonoid glycosides [astragalin (1), isoquercetin (2), rhamnocitrin 3-O-glucoside (3), and nicotiflorin (4)], a triterpene [methyl hederagenin (5)], and three types of triterpene glycosides [δ-hederin (6), echinocystic acid 3-O-arabinoside (7), and cauloside B (8)] from the methanol extract of E. sieboldianus, which regulates lipid accumulation in 3T3-L1 preadipocytes. Among the compounds isolated, 2 and 8 up- and down-regulated lipid accumulation and insulin induced adipocyte differentiation in 3T3-L1 preadipocytes. Compound 2 induced up-regulation of lipid accumulation and decreased adipocyte size, while 8 down-regulated lipid accumulations without decreasing cell size. Additionally, 2 increased adipogenic proteins [peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and fatty-acid-binding protein 4 (FABP4)]. In contrast, 8 decreased the levels of all adipogenic proteins and glucose transporter type 4 (GLUT4), but increased adiponectin.

Enhanced expression of Survivin has distinct roles in adipocyte homeostasis

Although precisely controlled lipolysis is crucial for maintaining physiological levels of circulating free fatty acids in response to energetic stress, the underlying mechanisms by which this process is governed remain poorly understood. Survivin is a gene that has been found to be highly expressed in the most common human tumors, and it is considered to be associated with tumorigenesis. Survivin expression in normal tissue is developmentally downregulated and is undetectable in most terminally differentiated adult tissues. Here, we report that Survivin expression in mature adipocytes from murine white adipose tissue can be highly induced under high-fat diet feeding conditions. During the adipocyte differentiation of 3T3-L1 preadipocytes and mesenchymal C3H10T1/2 cells, Survivin expression is gradually decreased and almost undetectable in fully differentiated adipocytes. However, it can be expressed again upon insulin exposure, through the PI3K/mTOR signaling pathway. Nevertheless, Survivin overexpression is sensitive to nutritional deprivation, and expression markedly decreases in response to starvation with Hank’s buffered salt solution challenge. The ectopic expression of Survivin downregulates expression of Adrb3 and then decreases the production of cAMP, while Fsp27 protein levels are upregulated as a result of reduced protein degradation. This in turn inhibits isoproterenol-stimulated adipocyte lipolysis. Survivin also attenuates DNA damage related to PARP activation and inhibits TNFα-induced lipolysis, suggesting that Survivin may facilitate adipocyte maintenance in response to inflammatory stimuli. Further studies will be undertaken to determine whether Survivin is critical for lipid storage to maintain metabolic homeostasis in vivo.

Epimedium koreanum Nakai and its main constituent icariin suppress lipid accumulation during adipocyte differentiation of 3T3-L1 preadipocytes

Obesity is associated with a number of metabolic abnormalities such as type 2 diabetes and has become a major health problem worldwide. In the present study, we investigated the effects of Epimedium koreanum Nakai (Herba Epimedii, HE) and its main constituent icariin on the adipocyte differentiation in 3T3-L1 preadipocytes. HE extract and icariin significantly reduced lipid accumulation and suppressed the expressions of PPARγ, C/EBPα, and SREBP-1c in 3T3-L1 adipocytes. They also inhibited fatty acid synthase (FAS), acyl-Co A synthase (ACS1), and perilipin. Moreover, HE extract and icariin markedly increased the phosphorylation of AMPK. These results indicated that HE extract and icariin can inhibit the adipocyte differentiation through downregulation of the adipogenic transcription factors, suggesting that HE containing icariin may be used as a potential therapeutic agent in the treatment and prevention of obesity.

Defatted safflower seed extract inhibits adipogenesis in 3T3-L1 preadipocytes and improves lipid profiles in C57BL/6J ob/ob mice fed a high-fat diet

In the present study, we hypothesized that defatted safflower seed which is known to be rich in polyphenols might influence adipogenesis and obesity-related disorders, and therefore the anti-adipogenic and hypolipidemic effects of ethanol extract from defatted safflower (Cathamus tinctorius L.) seeds (CSE) were investigated both in cultured 3T3-L1 preadipocytes and in C57BL/6J ob/ob mice fed a high-fat diet. CSE inhibited adipocyte differentiation of 3T3-L1 preadipocytes and decreased expression of the adipogenic transcription factors, SREBP1c and PPARγ, and their target genes. Six-week-old obese (ob/ob) mice were fed a high-fat diet and treated with CSE (50 or 100 mg/kg/day) by oral gavage for 6 weeks. Body fat mass (epididymal and perirenal white adipose tissues) in the CSE-treated groups was significantly lower than that in the high-fat diet control (HFD) group, whereas average daily food intake was not significantly different among the groups. Plasma and hepatic triglyceride levels and plasma low-density lipoprotein cholesterol level were also significantly lower in the CSE groups compared to the HFD group. These results suggest that CSE which decreases body fat mass and improves lipid profiles in plasma and liver, represents a potential treatment option for obesity and associated metabolic disorders, including hyperlipidemia.

The commonly used nonionic surfactant Span 80 has RXRα transactivation activity, which likely increases the obesogenic potential of oil dispersants and food emulsifiers

Obesity has reached pandemic proportions, and there is mounting evidence that environmental exposures to endocrine disrupting chemicals known as “obesogens” may contribute to obesity and associated medical conditions. The Deepwater Horizon (DWH) oil spill resulted in a massive environmental release of crude oil and remediation efforts applied large quantities of Corexit dispersants to the oil spill. The Corexit-enhanced Water Accommodated Fraction (CWAF) of DWH crude oil contains PPARγ transactivation activity, which is attributed to dioctyl sodium sulfosuccinate (DOSS), a probable obesogen. In addition to its use in oil dispersants, DOSS is commonly used as a stool softener and food additive. Because PPARγ functions as a heterodimer with RXRα to transcriptionally regulate adipogenesis we investigated the potential of CWAF to transactivate RXRα and herein demonstrated that the Corexit component Span 80 has RXRα transactivation activity. Span 80 bound to RXRα in the low micromolar range and promoted adipocyte differentiation of 3T3-L1 preadipocytes. Further, the combination of DOSS and Span 80 increased 3T3-L1 adipocyte differentiation substantially more than treatment with either chemical individually, likely increasing the obesogenic potential of Corexit dispersants. From a public health standpoint, the use of DOSS and Span 80 as food additives heightens concerns regarding their use and mandates further investigations.

Enzymatic fragments of hyaluronan inhibit adipocyte differentiation in 3T3-L1 pre-adipocytes

Hyaluronan has diverse biological activities depending on its molecular size. High molecular weight hyaluronan (2000 kDa) is a major component of extracellular matrix, and has been used in wounding healing, extracellular matrix regeneration, and in the treatment of osteoarthritis. Hyaluronan fragments can stimulate inflammation or induce loss of extracellular matrix. Hyaluronan is expressed during adipocyte differentiation, and down regulation of hyaluronan synthesis can reduce adipogenic differentiation. However, the direct effects of hyaluronan fragments on adipocyte differentiation have not been elucidated. Therefore, we prepared hyaluronan fragments by enzymatic digestion, and examined the inhibitory effects of these hyaluronan fragments on the accumulation of lipid droplets and on adipogenic gene mRNA expression in differentiating 3T3-L1 pre-adipocytes. Medium sized hyaluronan fragments (50 kDa) decreased lipid droplet accumulation in a dose-dependent manner. However, high molecular weight hyaluronan did not inhibit lipid droplet accumulation when used at a concentration of 600 μg/ml. Two or 4 day treatments with medium molecular weight of hyaluronan resulted in similar inhibitory levels of lipid accumulation as did treatment for 8 days. Medium sized hyaluronan inhibited the differentiation of 3T3-L1 pre-adipocytes during the early stages of adipogenesis. When 3T3-L1 cells were treated with 180 μg/ml of medium sized hyaluronan, the mRNAs for the master adipogenic transcription factors PPAR-γ and C/EBP-α were inhibited. Additionally, medium molecular weight hyaluronan suppressed mRNA expression of PPAR-γ target genes, including aP2 and FAS. This study is the first to report that medium molecular weight hyaluronan fragments can inhibit adipocyte differentiation.