Anti-Obesity Effect of Porcine Collagen Peptide in 3T3-L1 Adipocytes and High-Fat Diet-Fed Mice by Regulating Adipogenesis

Obesity is one of the most common diseases caused by an imbalance in the intake and expenditure of energy, and it is associated with various metabolic complications. This study aimed at investigating the anti-obesity effects and mechanisms of porcine collagen peptide (PCP) using 3T3-L1 preadipocytes and high-fat diet (HFD)-fed mice. The PCP treatment significantly inhibited the adipocyte differentiation and attenuated the mRNA expression of transcription factors (CCAAT/enhancer-binding protein alpha [C/EBPα] and peroxisome proliferator-activated receptor gamma [PPARγ]) and the lipogenic gene (fatty acid synthase [FAS]) expression in 3T3-L1 preadipocytes. In the in vivo study, HFD-fed mice were fed low- (1.5 g/kg body weight/day) and high- (4.5 g/kg body weight/day) PCP for 12 weeks and compared with the normal diet-fed group and HFD-fed control group. The PCP-fed groups showed significantly lower body weight gain, white fat weight gain, serum triglycerides, and adipocyte size compared with the HFD-fed group. The changes in body fat were associated with the upregulation of adiponectin and the downregulation of leptin, C/EBPα, PPARγ, and FAS. These results suggest that PCP has the potential to reduce obesity by suppressing adipogenesis and could be applied as a functional food material.

LncRNA MIR99AHG enhances adipocyte differentiation by targeting miR-29b-3p to upregulate PPARγ

AIM

The aim is to identify new long noncoding RNAs (lncRNAs) involved in adipocyte differentiation.

METHODS

High-throughput RNA sequencing of 3T3-L1 preadipocytes was carried out before and after differentiation to identify the target lncRNAs and miRNAs. The effects of lncRNA, miRNA and the network mechanism on adipocyte differentiation were evaluated in vitro and in vivo. Visceral adipose tissue (VAT) was collected from Chinese subjects with obesity or a normal body mass index (BMI), and the levels of lncRNAs, adipogenic genes and miRNAs were measured.

RESULTS

MIR99AHG, miR-29b-3p were selected as the target lncRNA and miRNA. Short hairpin RNA against MIR99AHG inhibited the differentiation of 3T3-L1 preadipocytes, reduced the expression of the peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT enhancer-binding protein alpha (C/EBPα) and fatty acid binding protein 4 (FABP4) genes, upregulated the expression of miR-29b-3p. Overexpression of MIR99AHG showed the opposite effects. Overexpression of miR-29b-3p inhibited the differentiation of 3T3-L1 preadipocytes and decreased the PPARγ level, while inhibition of miR-29b-3p showed the opposite effects. MIR99AHG and PPARγ competed for binding to miR-29b-3p. In mice with high-fat diet-induced obesity, MIR99AHG and miR-29b-3p mRNA level were increased and decreased, respectively. Tail vein injection of adeno-associated virus 9-MIR99AHG-RNA interference (AAV9-MIR99AHG-RNAi) reduced the body weight, epididymal fat mass, MIR99AHG level and increased the expression of miR-29b-3p. The expression levels of MIR99AHG, PPARγ, C/EBPα and FABP4 in human visceral adipose tissue were higher in the obese group than in the normal weight group.

CONCLUSIONS

MIR99AHG enhances adipogenesis by regulating miR-29b-3p and PPARγ, providing a new target for therapeutic intervention in obesity.

Lipase family member N is a novel target gene for CCAAT/enhancer-binding protein α in type 2 diabetic model mouse liver

CCAAT/enhancer-binding protein α (C/EBPα) is a transcription factor abundantly expressed in the liver and white adipose tissue (WAT). In this study, we investigated the mechanism by which C/EBPα regulates the lipase family member N (Lipn) gene in the mouse liver. Mouse Lipn consists of non-coding exon 1 and the translation start site located in exon 2. Lipn expression in the fatty liver of ob/ob mice was significantly higher than that in OB/OB mice and was significantly repressed by liver-specific C/EBPα deficiency. Lipn expression in ob/ob mice was detected in the liver, epididymal WAT (eWAT), subcutaneous WAT (sWAT), brown adipose tissue (BAT), and skeletal muscle, but not in the kidney, brain, and heart. Lipn expression in the liver, eWAT, and sWAT of wild-type mice was undetectable, although C/EBPα was highly expressed in these tissues. The database analysis revealed four putative C/EBP-responsive elements (CEBPREs), highly homologous with the typical CEBPRE consensus sequence at positions -2,686/-2,678, -1,364/-1,356, -106/-98, and -45/-37 from the transcription start site (+1) of Lipn. Reporter assays using reporter constructs with serial or internal deletions of the 5'-flanking regions of Lipn showed that two functional CEBPREs (-106/-98 and -45/-37) in the Lipn promoter region are essential for enhancing Lipn transcriptional activity by C/EBPα. Electrophoretic mobility shift assay showed that C/EBPα/β binds to CEBPRE (-106/-98). These results suggest that C/EBPα and type 2 diabetic environment may be required for hepatic Lipn expression.

Preventive effect of salicin ether against type-2 diabetes mellitus through targeting PPARγ-regulated gene expression

Diabetes mellitus is the syndrome associated with metabolism having complicated pathogenesis and its morbidity rate is rapidly increasing every year. The present study investigated the preventive effect of salicin ether against type-2 diabetes and explored the underlying mechanism. Salicin ether reduced PPARγ-LBD level and transcriptional property of RXRα-PPARγ in 293T cells. The rosiglitazone significantly (p<0.01) increased grease droplet accumulation in adipocytes in comparison to control adipocytes. Increased grease droplet accumulation by rosiglitazone in adipocytes was reversed on treatment with salicin ether in dose-dependent manner. Salicin ether treatment of the adipocytes effectively suppressed rosiglitazone induced expression of FAS, C/EBPα, aP2, and HMG-CoA genes. Treatment of the adipocytes with salicin ether led to a prominent decrease in rosiglitazone mediated increase in aP2, CHIP, and C/EBPα protein expression. The inhibitory effect of rosiglitazone on expression of p-Akt/t-Akt, PPARa, p-FoxO1/t-FoxO1, and p-AMPK/t-AMPK was significantly (p<0.01) alleviated in the adipocytes by salicin ether. In summary, the present study demonstrated that salicin ether suppressed PPARγ activity and adipocyte differentiation. Moreover, the activation of FoxO1/Akt/AMPK was up-regulated and FAS/EBPα/aP2/HMG-CoA level inhibited by salicin ether in the adipocytes. Thus, salicin ether may be studied further for possible role in the treatment of diabetes.

Tentatively Identified (UPLC/T-TOF-MS/MS) Compounds in the Extract of Saussurea costus Roots Exhibit In Vivo Hepatoprotection via Modulation of HNF-1α, Sirtuin-1, C/ebpα, miRNA-34a and miRNA-223

Saussurea costus is a plant traditionally used for the treatment of several ailments. Our study accomplished the UPLC/T-TOF-MS/MS analysis of a methanol extract of Saussurea costus roots (MESC), in addition to lipoidal matter determination and assessment of its in vivo hepatoprotective activity. In this study, we were able to identify the major metabolites in MESC rather than the previously known isolated compounds, improving our knowledge of its chemical constituents. The flavones apigenin, acacetin, baicalein, luteolin, and diosmetin, and the flavonol aglycones quercetin, kaempferol, isorhamnetin, gossypetin, and myricetin and/or their glycosides and glucuronic derivatives were the major identified compounds. The hepatoprotective activity of MESC was evaluated by measuring catalase activity using UV spectrophotometry, inflammatory cytokines and apoptotic markers using ELISA techniques, and genetic markers using PCR. Paracetamol toxicity caused a significant increase in plasma caspase 2, cytokeratin 18 (CK18), liver tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), miRNA-34a, and miRNA-223, as well as a significant decrease in liver catalase (CAT) activity and in the levels of liver nuclear factor 1α (HNF-1α), sirtuin-1, and C/ebpα. Oral pretreatment with MESC (200 mg/kg) showed a significant decrease in caspase 2, CK18, TNF-α, IL-6 and a significant increase in liver CAT activity. MESC decreased the levels of liver miRNA-34a and miRNA-223 and induced HNF-1α, sirtuin-1, and C/ebpα gene expression. The histological examination showed a significant normalization in rats pretreated with MESC. Our findings showed that Saussurea costus may exert a potent hepatoprotective activity through the modulation of the expression of cellular cytokines, miRNA-34a, and miRNA-223.

Novel Bacillus ginsengihumi CMRO6 Inhibits Adipogenesis via p38MAPK/Erk44/42 and Stimulates Glucose Uptake in 3T3-L1 Pre-Adipocytes through Akt/AS160 Signaling

The health benefits of probiotics have been known for decades, but there has only been limited use of probiotics in the treatment of obesity. In this study, we describe, for the first time, the role of cell-free metabolites (CM) from Bacillus ginsengihumi-RO6 (CMRO6) in adipogenesis and lipogenesis in 3T3-L1 pre-adipocytes. The experimental results show that CMRO6 treatment effectively reduced lipid droplet accumulation and the expression of CCAAT/enhancer-binding protein α and β (C/EBPα and C/EBPβ), peroxisome proliferator-activated receptor γ (PPAR-γ), serum regulatory binding protein 1c (SREBP-1c), fatty acid-binding protein 4 (FABP4), fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), phosphorylated p38MAPK, and Erk44/42. Additionally, CMRO6 treatment significantly increased glucose uptake and phosphorylated Akt (S473), AS160, and TBC1D1 protein expressions. Considering the results of this study, B. ginsengihumi may be a novel probiotic used for the treatment of obesity and its associated metabolic disorders.

Salvia miltiorrhiza Extract and Individual Synthesized Component Derivatives Induce Activating-Transcription-Factor-3-Mediated Anti-Obesity Effects and Attenuate Obesity-Induced Metabolic Disorder by Suppressing C/EBPα in High-Fat-Induced Obese Mice

Pharmacological studies indicate that Salvia miltiorrhiza extract (SME) can improve cardiac and blood vessel function. However, there is limited knowledge regarding the effects (exerted through epigenetic regulation) of SME and newly derived single compounds, with the exception of tanshinone IIA and IB, on obesity-induced metabolic disorders. In this study, we administered SME or dimethyl sulfoxide (DMSO) as controls to male C57BL/J6 mice after they were fed a high-fat diet (HFD) for 4 weeks. SME treatment significantly reduced body weight, fasting plasma glucose, triglyceride levels, insulin resistance, and adipogenesis/lipogenesis gene expression in treated mice compared with controls. Transcriptome array analysis revealed that the expression of numerous transcriptional factors, including activating transcription factor 3 (ATF3) and C/EBPα homologous protein (CHOP), was significantly higher in the SME group. ST32db, a novel synthetic derivative similar in structure to compounds from S. miltiorrhiza extract, ameliorates obesity and obesity-induced metabolic syndrome in HFD-fed wild-type mice but not ATF3^−/− mice. ST32db treatment of 3T3-L1 adipocytes suppresses lipogenesis/adipogenesis through the ATF3 pathway to directly inhibit C/EBPα expression and indirectly inhibit the CHOP pathway. Overall, ST32db, a single compound modified from S. miltiorrhiza extract, has anti-obesity effects through ATF3-mediated C/EBPα downregulation and the CHOP pathway. Thus, SME and ST32db may reduce obesity and diabetes in mice, indicating the potential of both SME and ST32db as therapeutic drugs for the treatment of obesity-induced metabolic syndrome.

Ajuba functions as a co-activator of C/EBPβ to induce expression of PPARγ and C/EBPα during adipogenesis

Adipogenesis is regulated by a complicated network of transcription factors among which PPARγ and C/EBP family members are the major regulators. During adipogenesis, C/EBPβ is induced early and then transactivates PPARγ and C/EBPα, which cooperatively induce genes whose expressions give rise to the mature adipocyte phenotype. Identifying the factors that influence the expression and activity of C/EBPβ should provide additional insight into the mechanisms regulating adipogenesis. Here, we demonstrate that depletion of Ajuba in 3T3-L1 cells significantly decreases mRNA and protein levels of PPARγ and C/EBPα and impairs adipocyte differentiation, while overexpression increases expression of these genes and promotes adipocyte differentiation. Moreover, restoration of C/EBPα or PPARγ expression in Ajuba-deficient 3T3-L1 cells improves the impaired lipid accumulation. Mechanistically, Ajuba interacts with C/EBPβ and recruits CBP to facilitate the binding of C/EBPβ to the promoter of PPARγ and C/EBPα, resulting in increased H3 histone acetylation and target gene expression. Collectively, these data indicate that Ajuba functions as a co-activator of C/EBPβ, and may be an important therapeutic target for combating obesity-related diseases.

Composition and structure elucidation of bovine milk glycosaminoglycans and their anti-adipogenic activity via modulation PPAR-γ and C/EBP-α

The structure function relation of Glycosaminoglycans from bovine milk (bmGAGs) has not been studied in detail. In the present study bmGAGs was isolated and structurally characterized. Chondroitin sulphate was one of the major GAGs present and had 65% of ΔDi-diSB (GlcA(2S)-GalNAc(4S)), followed by 18% of ΔDi-4S(Δ4,5HexUAα1 → 3GalNAc). Further, bmGAGs exhibited a marked anti-adipogenic effect in 3 T3-L1 cells without affecting cell viability at the concentration used. The triglyceride content treated with bmGAGs was significantly decreased as assessed by Oil-Red O staining. Peroxisome proliferator activated receptor γ (PPAR-γ) and CCAAT/enhancer-binding proteins (C/EBPα) the critical transcription factors in adipogenesis showed significant decrease in both gene and protein levels. Sterol regulatory element-binding protein 1c (SREBP-1c) that promotes the adipocyte differentiation by enhancing the activity of PPAR-γ was inversely affected by bmGAGs and the fatty acid synthase (FAS) expression was modulated. Thus, the present work is among the firsts to demonstrate an anti-adipogenic activity of bmGAGs by modulating the adipogenesis-related marker proteins and hence bmGAGs may be used as a supplement/therapeutic in the management of obesity.

Saikosaponin A and D Inhibit Adipogenesis via the AMPK and MAPK Signaling Pathways in 3T3-L1 Adipocytes

Obesity is a lipid metabolism disorder caused by genetic, medicinal, nutritional, and other environmental factors. It is characterized by a complex condition of excess lipid accumulation in adipocytes. Adipogenesis is a differentiation process that converts preadipocytes into mature adipocytes and contributes to excessive fat deposition. Saikosaponin A (SSA) and saikosaponin D (SSD) are triterpenoid saponins separated from the root of the Bupleurum chinensis, which has long been used to treat inflammation, fever, and liver diseases. However, the effects of these constituents on lipid accumulation and obesity are poorly understood. We investigated the anti-obesity effects of SSA and SSD in mouse 3T3-L1 adipocytes. The MTT assay was performed to measure cell viability, and Oil Red O staining was conducted to determine lipid accumulation. Various adipogenic transcription factors were evaluated at the protein and mRNA levels by Western blot assay and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Here, we showed that SSA and SSD significantly inhibited lipid accumulation without affecting cell viability within the range of the tested concentrations (0.938–15 µM). SSA and SSD also dose-dependently suppressed the expression of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), sterol regulatory element binding protein-1c (SREBP-1c), and adiponectin. Furthermore, the decrease of these transcriptional factors resulted in the repressed expression of several lipogenic genes including fatty acid binding protein (FABP4), fatty acid synthase (FAS), and lipoprotein lipase (LPL). In addition, SSA and SSD enhanced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylase (ACC), and inhibited the phosphorylation of extracellular-regulated kinase 1/2 (ERK1/2) and p38, but not c-Jun-N-terminal kinase (JNK). These results suggest that SSA and SSD inhibit adipogenesis through the AMPK or mitogen-activated protein kinase (MAPK) pathways in the early stages of adipocyte differentiation. This is the first study on the anti-adipogenic effects of SSA and SSD, and further research in animals and humans is necessary to confirm the potential of saikosaponins as therapeutic agents for obesity.

The effect of homocysteine on the expression of CD36, PPARγ, and C/EBPα in adipose tissue of normal and obese mice

The purpose of this study was to investigate the effect of homocysteine (Hcy) on CD36, PPARγ, and C/EBPα gene and protein expression in adipose tissue obtained from normal and high-calorie diet obesity models. CD36, PPARγ, and C/EBPα gene expression and protein levels in adipose tissue specimens were determined using the RT-PCR and ELISA methods, respectively. Significantly increased CD36 gene expression was observed in adipose tissue from obese mice, while Hcy significantly reduced CD36 gene expression in adipose tissue from normal and obese mice. PPARγ and C/EBPα gene expression levels decreased significantly in all groups compared to the normal group. In addition, levels of both PPARγ and C/EBPα gene expression were lower with Hcy supplementation compared to their own controls. In conclusion, Hcy's reduction of CD36 gene expression in adipose tissue may be one probable factor in hyperhomocysteinemia representing an independent risk factor for cardiovascular diseases.

Phytochemicals from the flowers of Prunus persica (L.) Batsch: Anti-adipogenic effect of mandelamide on 3T3-L1 preadipocytes

Flowers of Prunus persica (L.) Batsch (Rosaceae), known as peach blossoms, have been reported to exert anti-obesity effects by improving hepatic lipid metabolism in obese mice. However, little is known regarding the anti-adipogenic effects of the phenolic compounds isolated from P. persica flowers. This study investigated the inhibitory effects of compounds extracted from P. persica flowers (PPF) on adipogenesis in 3T3-L1 murine preadipocytes using adipogenic differentiation assays. Additionally, we compared the anti-adipogenic effects of the phenolic compounds isolated from PPF, such as prunasin amide (1), amygdalin amide (2), prunasin acid (3), mandelamide (4), methyl caffeate (5), ferulic acid (6), chlorogenic acid (7), benzyl α-l-xylpyranosyl-(1 → 6)-β-d-glucopyranoside (8), prunin (9), naringenin (10), nicotiflorin (11), astragalin (12), afzelin (13), and uridine (14), on adipogenesis in 3T3-L1 murine preadipocytes. PPF and compounds 4-7 and 10 significantly inhibited adipogenesis. Among them, mandelamide (4) exhibited the maximum inhibitory activity with an IC₅₀ of 36.04 ± 1.82 μM. Additionally, mandelamide downregulated the expression of key adipogenic markers, such as extracellular signal-regulated kinase, c-Jun-N-terminal kinase, P38, CCAAT/enhancer-binding protein α, CCAAT/enhancer-binding protein β, peroxisome proliferator activated receptor γ, and glucocorticoid receptor. These results indicate that mandelamide is an active ingredient of PPF possessing anti-obesity properties.

Inhibition of Lipid Accumulation and Cyclooxygenase-2 Expression in Differentiating 3T3-L1 Preadipocytes by Pazopanib, a Multikinase Inhibitor

Pazopanib is a multikinase inhibitor with anti-tumor activity. As of now, the anti-obesity effect and mode of action of pazopanib are unknown. In this study, we investigated the effects of pazopanib on lipid accumulation, lipolysis, and expression of inflammatory cyclooxygenase (COX)-2 in differentiating and differentiated 3T3-L1 cells, a murine preadipocyte. Of note, pazopanib at 10 µM markedly decreased lipid accumulation and triglyceride (TG) content during 3T3-L1 preadipocyte differentiation with no cytotoxicity. Furthermore, pazopanib inhibited not only expression of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), and perilipin A but also phosphorylation of signal transducer and activator of transcription (STAT)-3 during 3T3-L1 preadipocyte differentiation. In addition, pazopanib treatment increased phosphorylation of cAMP-activated protein kinase (AMPK) and its downstream effector ACC during 3T3-L1 preadipocyte differentiation. However, in differentiated 3T3-L1 adipocytes, pazopanib treatment did not stimulate glycerol release and hormone-sensitive lipase (HSL) phosphorylation, hallmarks of lipolysis. Moreover, pazopanib could inhibit tumor necrosis factor (TNF)-α-induced expression of COX-2 in both 3T3-L1 preadipocytes and differentiated cells. In summary, this is the first report that pazopanib has strong anti-adipogenic and anti-inflammatory effects in 3T3-L1 cells, which are mediated through regulation of the expression and phosphorylation of C/EBP-α, PPAR-γ, STAT-3, ACC, perilipin A, AMPK, and COX-2.

Syringin: A Phenylpropanoid Glycoside Compound in Cirsium brevicaule A. GRAY Root Modulates Adipogenesis

Cirsium brevicaule A. GRAY is a wild perennial herb, and its roots (CbR) have traditionally been used as both food and medicine on the Japanese islands of Okinawa and Amami. The present study evaluated the antiadipogenic effect of CbR using mouse embryonic fibroblast cell line 3T3-L1 from JCRB cell bank. Dried CbR powder was serially extracted with solvents of various polarities, and these crude extracts were tested for antiadipogenic activity. Treatment with the methanol extract of CbR showed a significant suppression of lipid accumulation in 3T3-L1 cells. Methanol extract of CbR was then fractionated and subjected to further activity analyses. The phenylpropanoid glycosidic molecule syringin was identified as an active compound. Syringin dose dependently suppressed lipid accumulation of 3T3-L1 cells without cytotoxicity, and significantly reduced the expressions of peroxisome proliferator-activated receptor gamma, the master regulator of adipogenesis, and other differentiation markers. It was demonstrated that syringin effectively enhanced the phosphorylation of the AMP-activated protein kinase and acetyl-CoA carboxylase. These results indicate that syringin attenuates adipocyte differentiation, adipogenesis, and promotes lipid metabolism; thus, syringin may potentially serve as a therapeutic candidate for treatment of obesity.

ACOX1, regulated by C/EBPα and miR-25-3p, promotes bovine preadipocyte adipogenesis

Acyl-coenzyme A oxidase 1 (ACOX1) is the first and rate-limiting enzyme in peroxisomal fatty acid β-oxidation of fatty acids. Previous studies have reported that ACOX1 was correlated with the meat quality of livestock, while the role of ACOX1 in intramuscular adipogenesis of beef cattle and its transcriptional and post-transcriptional regulatory mechanisms remain unclear. In the present study, gain-of-function and loss-of-function assays demonstrated that ACOX1 positively regulated the adipogenesis of bovine intramuscular preadipocytes. The C/EBPα-binding sites in the bovine ACOX1 promoter region at -1142 to -1129 bp, -831 to -826 bp, and -303 to -298 bp were identified by promoter deletion analysis and site-directed mutagenesis. Electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation (ChIP) further showed that these three regions are C/EBPα-binding sites, both in vitro and in vivo, indicating that C/EBPα directly interacts with the bovine ACOX1 promoter and inhibits its transcription. Furthermore, the results from bioinformatics analysis, dual luciferase assay, site-directed mutagenesis, qRT-PCR, and Western blotting demonstrated that miR-25-3p directly targeted the ACOX1 3'UTR (3'UTR). Taken together, our findings suggest that ACOX1, regulated by transcription factor C/EBPα and miR-25-3p, promotes adipogenesis of bovine intramuscular preadipocytes via regulating peroxisomal fatty acid β-oxidation.

Cudratricusxanthone A Inhibits Lipid Accumulation and Expression of Inducible Nitric Oxide Synthase in 3T3-L1 Preadipocytes

Cudratricusxanthone A (CTXA) is a natural bioactive compound extracted from the roots of Cudrania tricuspidata Bureau and has been shown to possess anti-inflammatory, anti-proliferative, and hepatoprotective activities. However, at present, anti-adipogenic and anti-inflammatory effects of CTXA on adipocytes remain unclear. In this study, we investigated the effects of CTXA on lipid accumulation and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, two known inflammatory enzymes, in 3T3-L1 preadipocytes. Strikingly, CTXA at 10 µM markedly inhibited lipid accumulation and reduced triglyceride (TG) content during 3T3-L1 preadipocyte differentiation with no cytotoxicity. On mechanistic levels, CTXA at 10 µM suppressed not only expression levels of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), and perilipin A, but also phosphorylation levels of signal transducer and activator of transcription-3 (STAT-3) and STAT-5 during 3T3-L1 preadipocyte differentiation. In addition, CTXA at 10 µM up-regulated phosphorylation levels of cAMP-activated protein kinase (AMPK) while down-regulating expression and phosphorylation levels of acetyl-CoA carboxylase (ACC) during 3T3-L1 preadipocyte differentiation. Moreover, CTXA at 10 µM greatly attenuated tumor necrosis factor (TNF)-α-induced expression of iNOS, but not COX-2, in 3T3-L1 preadipocytes. These results collectively demonstrate that CTXA has strong anti-adipogenic and anti-inflammatory effects on 3T3-L1 cells through control of the expression and phosphorylation levels of C/EBP-α, PPAR-γ, FAS, ACC, perilipin A, STAT-3/5, AMPK, and iNOS.

Cloning and functional analysis of c/ebpα as negative regulator of dmrt1 in Chinese tongue sole (Cynoglossus semilaevis)

c/ebpα is a member of the C/EBP family of transcription factors, which are involved in cell growth and differentiation and have a conserved basic leucine zipper (bZIP) domain. However, little is known about its function in sex determination and differentiation. In the present study, c/ebpα was cloned from the gonads of Chinese tongue sole (Cynoglossus semilaevis). The full-length cDNA of c/ebpα was 1583 bp, with a 198-bp 5' UTR, a 446-bp 3' UTR, and a 939-bp open reading frame encoding a 312-amino acid peptide. qRT-PCR revealed that c/ebpα was predominantly expressed in undifferentiated gonads of male C. semilaevis at 30 dpf and 60 dpf and peaked at 60 dpf. Expression levels of c/ebpα in the testis were constantly higher than those in ovaries at all developmental stages. Moreover, a dual-luciferase assay revealed that c/ebpα could negatively regulate the male-determining gene dmrt1 in vitro. These results provide fundamental information indicating that C. semilaevis c/ebpa might be involved in early gonadal differentiation and functions as a negative regulator of dmrt1 by repressing its transcription.

MicroRNA 182 is a Novel Negative Regulator of Adipogenesis by Targeting CCAAT/Enhancer-Binding Protein α

OBJECTIVE

Recent studies have shown that microRNAs (miRNAs/miRs) play key roles in adipogenesis. This study aimed to investigate the role and underlying mechanism of miR-182 in adipogenesis.

METHODS

This study used the 3T3-L1 cell line and human visceral adipose tissue (VAT)-derived adipocytes to determine the role of miR-182 in adipogenesis. Adipose tissues from mice with high-fat diet-induced obesity, ob/ob mice, or human individuals with obesity were used to determine the association of miR-182 levels with obesity. A luciferase reporter assay was used to determine the target of miR-182.

RESULTS

The expression level of miR-182 was greatly downregulated during white adipogenesis and markedly lower in the VAT of mice and humans with obesity. Ectopic expression of miR-182 in 3T3-L1 cells and human adipocytes suppressed the formation of lipid droplets and the expression of adipogenic genes. The luciferase reporter assay showed that miR-182 targeted the 3'-untranslated sequence of CCAAT/enhancer-binding protein α (C/EBPα) directly. In addition, glucocorticoids negatively regulated miR-182 expression, which, in turn, suppressed the glucocorticoid-induced expression of C/EBPα.

CONCLUSIONS

Taken together, our studies identified miR-182 as a novel negative regulator of adipogenesis and a potential therapeutic target for obesity.

SIRT7: an influence factor in healthy aging and the development of age-dependent myeloid stem-cell disorders

Molecular alterations within the hematopoietic system influence cellular longevity and development of age-related myeloid stem-cell disorders like acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). A reduced SIRT7-expression in aged murine hematopoietic stem cells (HSC) resulted in reduced longevity and increased proliferation. In this study we investigated age-related changes of SIRT7-expression in healthy humans and relevant pathomechanisms in AML and CML. SIRT7-expression in leukocytes of healthy people decreased in an age-dependent manner. Low SIRT7 mRNA levels were also detected in AML and CML patients. With positive treatment response, SIRT7-expression increased, but showed reduction when patients progressed or relapsed. Pharmacologic inhibition of driver mutations in AML (FLT3-ITD) or CML (BCR-ABL) also restored SIRT7 levels in cell lines and patient samples. Furthermore, SIRT7-expression increased with time during PMA-mediated monocyte differentiation of THP-1 cells. SIRT7-overexpression in THP-1 cells resulted in increased expression of differentiation markers. BCR-ABL, FLT3-ITD, and differentiation-associated SIRT7-expression in general were positively regulated by C/EBPα, -β, and -ε binding to two different C/EBP-binding sites within the SIRT7 promoter. SIRT7 is important in human hematopoietic cell aging and longevity. It might act as tumor suppressor and could potentially serve as general biomarker for monitoring treatment response in myeloid stem-cell disorders.

Anti-oxidative and anti-adipogenic effects of caffeine in an in vitro model of Graves' orbitopathy

Oxidative stress and adipogenesis play key roles in the pathogenesis of Graves' orbitopathy (GO). In this study, the therapeutic effects of caffeine on the reduction of oxidative stress and adipogenesis were evaluated in primary cultured GO orbital fibroblasts in vitro. Orbital fibroblasts were cultured from orbital connective tissues obtained from individuals with GO. Intracellular reactive oxygen species (ROS) levels induced by hydrogen peroxide or cigarette smoke extract and the expression of anti-oxidative enzymes were measured after caffeine treatment. After adipogenic differentiation and caffeine treatment, cells were stained with Oil Red O and the levels of peroxisome proliferator activator γ (PPARγ), C/EBPα, and C/EBPβ were determined by western blot analysis. Hydrogen peroxide and cigarette smoke extract increased the levels of intracellular ROS and anti-oxidative enzymes, which decreased in a dose-dependent manner upon pretreatment with caffeine in GO orbital fibroblasts. Oil Red-O staining results revealed a decrease in lipid droplets; furthermore, PPARγ, C/EBPα, and C/EBPβ protein expression levels were inhibited upon treatment with caffeine during adipocyte differentiation. In conclusion, caffeine decreased oxidative stress and adipogenesis in GO orbital fibroblasts in vitro. These findings may contribute to the development of new types of caffeine-containing pharmacological agents for use in the management of GO.

Genistin: A Novel Potent Anti-Adipogenic and Anti-Lipogenic Agent

Soy isoflavones are popular ingredients with anti-adipogenic and anti-lipogenic properties. The anti-adipogenic and anti-lipogenic properties of genistein are well-known, but those of genistin and glycitein remain unknown, and those of daidzein are characterized by contrasting data. Therefore, the purpose of our study was to investigate the effects of daidzein, glycitein, genistein, and genistin on adipogenesis and lipogenesis in 3T3-L1 cells. Proliferation of 3T3-L1 preadipocytes was unaffected by genistin and glycitein, but it was affected by 50 and 100 µM genistein and 100 µM daidzein for 48 h. Among the four isoflavones, only 50 and 100 µM genistin and genistein markedly suppressed lipid accumulation during adipogenesis in 3T3-L1 cells through a similar signaling pathway in a dose-dependent manner. Genistin and genistein suppress adipocyte-specific proteins and genes, such as peroxisome proliferator-activated receptor γ (PPARγ), CCAAT-enhancer-binding protein α (C/EBPα), and adipocyte binding protein 2 (aP2)/fatty acid-binding protein 4 (FABP4), and lipogenic enzymes such as ATP citrate lyase (ACL), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FAS). Both isoflavones also activate AMP-activated protein kinase α (AMPKα), an essential factor in adipocyte differentiation, and inhibited sterol regulatory element-binding transcription factor 1c (SREBP-1c). These results indicate that genistin is a potent anti-adipogenic and anti-lipogenic agent.

Cerasus humilis Cherry Polyphenol Reduces High-Fat Diet-Induced Obesity in C57BL/6 Mice by Mitigating Fat Deposition, Inflammation, and Oxidation

This study aimed to determine the anti-obesity effects and mechanisms of Cerasus humilis polyphenol (CHP) in C57BL/6 obese mice and 3T3-L1 cells. High-performance liquid chromatography-electrospray ionization-tandem mass spectrometry was used for the qualitative and quantitative identification of CHP components. The obese mice, induced by feeding high-fat diet (HFD), were treated with CHP (250 mg/kg/day) by gavage for 12 weeks. Orlistat was gavaged at 15.6 mg/kg bw/day, as a positive control group. The analysis revealed that the main components of CHP were procyanidin B2, cyanidin-3-glucoside, and pelargonidin-3-glucoside. CHP dietary supplementation significantly reduced body weight and improved blood lipid measurements in HFD-fed mice (p < 0.01). Moreover, it inhibited mRNA expression of miR-122, Srebp-1c, and Cpt1a (p < 0.01) and reduced hepatic lipid deposition, as seen by hematoxylin and eosin staining. CHP downregulated the protein expression of PPARγ and C/EBPα in HFD-induced obese mice and inhibited adipocyte differentiation (p < 0.01). Compared with the HFD group, CHP supplementation had an obvious anti-inflammatory effect (decreased protein expression, such as TNF-α, IL-6, and MCP1), reducing leptin levels and TNF-α secretion in serum and cells (p < 0.01). CHP significantly inhibited the expression of miR-27a/b (53.3 and 29.9%, p < 0.01) in mice retroperitoneal white adipocytes, enhancing the expression of the target gene Prdm16 and significantly upregulating Sirt1 (105.5%, p < 0.01) compared with the HFD group. Moreover, CHP supplementation effectively improved oxidative stress (ROS, T-AOC, SOD, CAT, and GSH-Px) induced by HFD in obese mice (p < 0.01). Thus, CHP mitigates adipocyte differentiation, browning of white adipocytes, and reduction of inflammation and antioxidant activity to reduce obesity. Consequently, these results provide novel insights into the anti-obesity roles of CHP in HFD-induced obesity.

Transcriptional Regulation of HMOX1 Gene in Hezuo Tibetan Pigs: Roles of WT1, Sp1, and C/EBPα

Heme oxygenase 1 (HMOX1) is a stress-inducing enzyme with multiple cardiovascular protective functions, especially in hypoxia stress. However, transcriptional regulation of swine HMOX1 gene remains unclear. In the present study, we first detected tissue expression profiles of HMOX1 gene in adult Hezuo Tibetan pig and analyzed the gene structure. We found that the expression level of HMOX1 gene was highest in the spleen of the Hezuo Tibetan pig, followed by liver, lung, and kidney. A series of 5’ deletion promoter plasmids in pGL3-basic vector were used to identify the core promoter region and confirmed that the minimum core promoter region of swine HMOX1 gene was located at −387 bp to −158 bp region. Then we used bioinformatics analysis to predict transcription factors in this region. Combined with site-directed mutagenesis and RNA interference assays, it was demonstrated that the three transcription factors WT1, Sp1 and C/EBPα were important transcription regulators of HMOX1 gene. In summary, our study may lay the groundwork for further functional study of HMOX1 gene.

Mulberry Fruit Extract Ameliorates Adipogenesis via Increasing AMPK Activity and Downregulating MicroRNA-21/143 in 3T3-L1 Adipocytes

Mulberry (Morus alba L.) fruits have long been used in traditional medicine and as edible berries in many countries. This study investigated the antiadipogenic effect of high hydrostatic pressure mulberry fruit extract (MFE) during 3T3-L1 adipocyte differentiation. MFE decreased lipid and triglyceride accumulation and glycerol-3-phosphate dehydrogenase activity. The mRNA expression levels of genes related to adipogenesis, such as the adipocyte protein 2, proliferator-activated receptor-γ, and CCAAT/enhancer binding protein-α, were suppressed by MFE. They also reduced microRNA (miR)-21 and miR-143 expression, which are involved in adipogenesis. In contrast, adenosine monophosphate-activated protein kinase (AMPK) activity was increased by MFE. These results suggested that MFE may suppress adipogenesis through modulating miR-21/143 expression and AMPK activity in 3T3-L1 adipocytes, which may be useful as antiobesity food agents.

Opposing roles of C/EBPα and eEF1A1 in Sp1-regulated miR-122 transcription

We previously showed that miR-122 was frequently downregulated in hepatocellular carcinoma (HCC) and C/EBPα transactivated miR-122 expression. In this study, we found that Sp1 bound to the miR-122 promoter at two different sites. Interestingly, either inhibition or overexpression of Sp1 could decrease the miR-122 promoter activity and the cellular miR-122 level in hepatoma cells. Further investigations disclosed that Sp1 cooperated with C/EBPα to induce miR-122 transcription by binding to the positive regulatory site D in the miR-122 promoter, whereas eEF1A1 interacted with Sp1 to bind to the negative regulatory site E and inhibit miR-122 transcription. Significantly, both Sp1 and eEF1A1 levels were enhanced, but C/EBPα and miR-122 expression were reduced in HCC tissues. Knockdown of eEF1A1 enhanced miR-122 level and inhibited cell growth, and these effects were abrogated when Sp1 was silenced. Consistently, the promoter activity enhanced by site E deletion was attenuated by silencing Sp1. Moreover, reduction of miR-122 resulted from Sp1 overexpression was rescued by coexpressing C/EBPα. These data suggest that C/EBPα and eEF1A1 may play opposing roles in Sp1-regulating miR-122 transcription, and the eEF1A1 upregulation accompanied by C/EBPα downregulation in HCC may switch the regulatory functions of Sp1 and led to reduced miR-122 transcription. These findings highlight the complex regulatory network of miR-122 expression and its significance in hepatocarcinogenesis.Abbreviations: MiRNA: microRNA; HCC, hepatocellular carcinoma; eEF1A1: eukaryote translation elongation factor 1A1; siRNA: small interfering RNA; qPCR: real-time quantitative RT-PCR; EMSA: electrophoretic mobility shift assay; ChIP: chromatin immunoprecipitation; TSS: transcription start site.