Inhibits Adipocyte Differentiation Research Articles

Abstract 5723: JDP2 interacts with p53 and enhances p53 transactivation and stability

Abstract USAAP-1 protein mainly consists of proteins belonging to c-Jun, c-Fos, activating transcription factor (ATF), and Jun dimerization protein (JDP) family. In addition to AP-1 site, JDP2 also binds to cAMP responsive element (CRE) site in numerous cis-elements of the target genes. JDP2 has been shown to be involved in cancer development and cell-cycle regulation, suppression of adipocyte differentiation, and controlling bone homeostasis and antibacterial immunity. ATF3 and JDP2 share high similarity in C-terminal domains with identities of 65%. Previous studies have demonstrated that ATF3 can bind to p53 and regulate p53 transcriptional activity and stability. Though couple of studies have shown that JDP2 inhibits expression of p53 and p53 represses the transcriptional activity of JDP2 promoter; however, whether JDP2 directly interacts and regulates p53 transactivation remains largely unknown. Herein, we demonstrate for the first time that JDP2 can directly interact with p53. First, we found that both ATF3 and JDP2 can bind to p53 and the C-terminus of JDP2 is required for p53 binding. Secondly, in p53-null H1299 cells, JDP2 dose-dependently enhances p53 transactivation using p53RE-Luc (14X). Moreover, we demonstrated that JDP2 dose-dependently decreases p53 protein level in consistence with the previous reports. Finally, JDP2 increases p53 stability in CHX chase experiments. Taken together, our results demonstrate that JDP2 directly binds to p53 and enhances p53 transactivation and stability, suggesting that JDP2 is a novel regulator of p53. Citation Format: Wei-Hsiung Yang, Kasey Price, Leticia Cardoso, William Yang, Chiung-Min Wang, Richard Yang. JDP2 interacts with p53 and enhances p53 transactivation and stability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5723.

DEPP Deficiency Contributes to Browning of White Adipose Tissue.

Decidual protein induced by progesterone (DEPP) was originally identified as a modulator in the process of decidualization in the endometrium. Here, we define that DEPP is involved in adipose tissue thermogenesis, which contributes to metabolic regulation. Knockdown of DEPP suppressed adipocyte differentiation and lipid accumulation in 3T3-L1 cells, induced expression of brown adipose tissue (BAT) markers in primary brown adipocyte and induced mouse embryonic fibroblasts (MEFs) differentiation to brown adipocytes. Moreover, DEPP deficiency in mice induced white adipocyte browning and enhanced BAT activity. Cold exposure stimulated more browning of white adipose tissue (WAT) and maintained higher body temperature in DEPP knockout mice compared to that in wild-type control mice. DEPP deficiency also protected mice against high-fat-diet-induced insulin resistance. Mechanistic studies demonstrated that DEPP competitively binds SIRT1, inhibiting the interaction between peroxisome proliferator-activated receptor gamma (PPARγ) and Sirtuin 1 (SIRT1). Collectively, these findings suggest that DEPP plays a crucial role in orchestrating thermogenesis through regulating adipocyte programs and thus might be a potential target for the treatment of metabolic disorders.

1403-P: DA-1726, a Balanced GLP1R/GCGR Dual Agonist, Effectively Controls Both Body Weight and Blood Glucose

DA-1726 is a novel balanced long-acting oxyntomodulin (OXM) analogue, which is under preclinical development for the treatment of obesity. In this study, the pharmacological effects of DA-1726 were evaluated. DA-1726 exhibited a balanced dual action on GLP-1 receptor (GLP1R) and glucagon receptor (GCGR) in CHO-K1 cells transiently overexpressing each human receptor. In high-fat diet-induced obese mice, 3-week treatment of DA-1726 showed more body weight loss (BWL) and increasing energy expenditure than a pair-fed group. This means that the BWL effect of DA-1726 is due to decreased food intake and increased energy metabolism through GLP1R and GCGR action. In comparison with a GLP1R agonist, DA-1726 showed superior BWL, despite eating more food compared to semaglutide (SEMA) after 4-week treatment in obese mice. At the end of the study, DA-1726 significantly increased the expression of thermogenic genes (Ucp-1 and Ppargc1a) in white adipose tissue (WAT) , and increased WAT browning was histologically confirmed. In addition, DA-1726 inhibited adipocyte differentiation in vitro. Taken together, it suggests that the GCGR action of DA-1726 contributes to reduced adiposity by enhancing fat burning and inhibiting adipogenesis. OXM analogue biased to GCGR fails to control blood glucose despite GLP1R agonism. As a balanced analogue, DA-1726 effectively reduced postprandial glucose excursion in acute oral glucose tolerance test in normal mice. Notably, DA-1726 showed similar glycemic control and excellent BWL to SEMA in hyperglycemic and obese FATZO mice after 4-week treatment. Simultaneously, DA-1726 enhanced insulin sensitivity by significantly reducing fasting plasma insulin and glucose levels. Meanwhile, DA-1726 showed no hypoglycemia risk in overnight fasted normal mice unlike SEMA after a single injection, regardless of dose escalation. Our findings suggest that DA-1726 is a balanced GLP1R/GCGR dual agonist that effectively reduces body weight and blood glucose levels. Disclosure T.Kim: None. I.Jung: None. K.Kim: None. B.Lee: None. M.Kim: None. Y.Chae: None.

METTL3 Regulated the Meat Quality of Rex Rabbits by Controlling PCK2 Expression via a YTHDF2-N6-Methyladenosine Axis.

N6-methyladenosine (m6A) is the most prevalent internal mRNA modification in eukaryotes. The M6A modification plays an important role in transcription and cell function. The mechanism by which m6A modification regulates meat quality remains elusive. In this study, gene knockout and overexpression were used to explore m6A-modified regulation of meat quality. The content of PCK2 in blood increased significantly with the increase of Rex rabbits’ age. PCK2 expression levels in the longissimus lumborum and liver also increased significantly with the increase of Rex rabbits’ age. However, the expression level of PCK2 showed no significant difference in adipose tissue. In cell experiments, we found that METTL3 inhibited adipocyte differentiation by targeting the PCK2 gene via the recognition function of YTHDF2. Finally, the results of correlation analysis showed that PCK2 expression was positively correlated with intramuscular fat, whereas PCK2 expression was negatively correlated with total water loss rate at three different stages. In addition, PCK2 expression was also negatively correlated with reduced pH value at 75 and 165 days. Intramuscular fat content, pH and muscle water holding capacity are the main factors affecting the taste and flavor of muscle. Therefore, N6-methyladenosine regulated muscle quality by targeting the PCK2 gene.

Inhibitory effect of saffron, crocin, crocetin, and safranal against adipocyte differentiation in human adipose-derived stem cells

Saffron (Crocus sativus L.) has been introduced as a potential promising natural antioxidant with anti-obesity properties. In Persian Medicine, saffron has been used to control appetite and obesity. The present study aims to investigate the effect of saffron and its bioactive compounds on adipocyte differentiation in human adipose-derived stem cells (ADSCs). Flow-Cytometric analysis was performed to quantify the cell surface markers. The extracts cytotoxicity on hASCs was measured using alamarBlue® assay whereas their activities against adipocyte differentiation were studied using Oil Red O staining. The level of Peroxisome proliferator-activated receptor-γ (PPARγ), Fatty Acid Synthetase (FAS), and Glyceraldehyde-3-phosphate dehydrogenase (GAPHD) which are key proteins in cell differentiation was investigated by western blot analysis. Flow-cytometry revealed the mesenchymal stem cells markers, CD44 and CD90, on ADSCs surface. The saffron, crocin, and crocetin significantly inhibited adipocyte differentiation while saffron up to 20μg/mL and crocin, crocetin and safranal up to 20μM did not exhibit cytotoxicity. The western blotting analysis revealed a remarkable reduction in the level of PPARγ, GAPDH, and FAS proteins by 10 and 20μM of crocin and 2.5 and 5μM of crocetin. It seems that saffron, crocin, and crocetin could efficiently inhibit the differentiation of hASCs with benefits for the treatment and prevention of obesity.

Anti-adipogenic β-sitosterol and lupeol from Moringa oleifera suppress adipocyte differentiation through regulation of cell cycle progression.

Triterpenes and phytosterols enriched herbal formulations are known for glucose regulation and lipid metabolism. In this study, triterpenes and phytosterols from Moringa oleifera stem bark have been tested for their role in adipocyte differentiation. Chromatographic analysis revealed a wide range of phenolics, highlighting the presence of flavonoids (kaempferol, quercetin, and rutin), terpenoids (lupeol), and phytosterol (stigmasterol, β-sitosterol). Lupeol and β-sitosterol reduced cell viability in a dose-dependent manner showcasing increased G1 phase cell accumulation while reducing other cell cycle phases (S and G2 /M) and significant lowering of intracellular lipid accumulation. Additionally, lupeol (35.37% at 32 μM) and β-sitosterol (42.97% at 16 μM) inhibited reactive oxygen species generation and increased glucose uptake in adipocytes. Collectively, our results indicate that lupeol and β-sitosterol efficaciously attenuated adipogenesis via a controlled cell cycle progression and enhanced glucose uptake in adipocytes. PRACTICAL APPLICATIONS: Active components of Moringa oleifera effectively regulate adipocyte differentation suggest that it can be good medicial supllement for control of obesity.

Heme oxygenase‐1 induction by gallic acid‐ g ‐chitosan is an important event in modulating adipocyte differentiation

Obesity, one of the common worldwide chronic health diseases co-relates with adipogenesis. Adipogenesis is a complex biological action of the emergence of mature adipocytes from the differentiation of pre-adipocytes and the disfunction of this process leads to the development of metabolic issues in obesity. Recently, much attention has been paid to utilizing natural compounds to discover their biological activities. This study focused on investigating the probable anti-adipogenic effects of gallic acid-g-chitosan (GAC) and plain chitosan (PC) through regulating the heme oxygenase-1 (HO-1)/Nrf2 pathway on mesenchymal stem cells. Gallic acid is grafted onto the PC backbone to improve its specific physical and biological properties. GAC showed promising anti-adipogenic effects by enhancing HO-1 expression and lipolysis and as well as suppressing lipid accumulation, reactive oxygen species, and pro-inflammatory cytokines production, transcription factor expression compared to the PC treatment. On the contrary, zinc protoporphyrin ІX (ZnPP), a HO-1 inhibitor reversed these effects of GAC on adipogenesis. Taken all together, this study revealed that grafting GA onto the chitosan improved potential anti-adipogenic activity by induction of the HO-1/Nrf2 pathway on mesenchymal stem cells (MSCs). PRACTICAL APPLICATIONS: GAC is a well-known copolymer with versatile bioactivities such as antimicrobial, antioxidant, and anti-diabetic activity. However, the anti-adipogenic effect of GAC has not been explored in MSCs. This study demonstrated that GAC inhibited adipocyte differentiation in MSCs through HO-1 activation. These findings suggest that GAC can be applied practically from different perspectives. GAC can be applied in the pharmacological industry to the development of anti-obesity drugs, medicinal perspectives for the treatment of obesity and obesity-related diseases, and in the food industry as a functional food to promote health and decrease the risk of diseases.

Isorhamnetin at Physiologically Attainable Nanomolar Concentrations Inhibits Adipocyte differentiation and Lipid Droplet Accumulation in vitro

Differentiation of preadipocytes into adipocytes is a major step leading to obesity. This study examines the effects of isorhamnetin, a metabolite of quercetin, at physiological and supraphysiological concentrations on the differentiation of 3T3-L1 pre-adipocyte to adipocyte. Comparison was made with the effect of quercetin on 3T3-L1 differentiation under the same conditions. Cell viability during adipocyte differentiation for 8 days in the presence of isorhamnetin and quercetin was above 94% and 97%, respectively. Oil Red O staining showed significant differences (P < 0.05) between the effect of isorhamnetin or quercetin on cytoplasmic lipid droplet accumulation and control untreated cells. Isorhamnetin at physiologically attainable concentrations was more effective than quercetin in inhibiting cytoplasmic lipid droplet accumulation. Neither isorhamnetin nor quercetin had an effect on the expression of macrophage chemoattractant protein -1 (MCP-1). CCAAT/enhancer binding protein α (C/EBP-α) was down-regulated by isorhamnetin. Compared to control, isorhamnetin or quercetin decreased PPAR-γ 1 and 2 expressions. The data indicate that isorhamnetin more than quercetin was effective at physiologically attainable concentrations in reducing lipid accumulation in 3T3-L1 pre-adipocytes.

Genetic and cytometric analyses of subcutaneous adipose tissue in patients with hemophilia and HIV-associated lipodystrophy

BackgroundThe authors recently performed plastic surgeries for a small number of patients with hemophilia, HIV infection, and morphologic evidence of lipodystrophy. Because the pathophysiological mechanism of HIV-associated lipodystrophy remains to be elucidated, we analyzed subcutaneous adipose tissues from the patients.MethodsAll six patients had previously been treated with older nucleoside analogue reverse-transcriptase inhibitors (NRTIs; stavudine, didanosine or zidovudine). Abdominal and inguinal subcutaneous fat samples were obtained from the HIV+ patients with hemophilia and HIV− healthy volunteers (n = 6 per group), and analyzed via DNA microarray, real-time PCR, flow cytometry and immunohistochemistry.ResultsThe time from initial NRTI treatment to collecting samples were 21.7 years in average. Cytometric analysis revealed infiltration of inflammatory M1 macrophages into HIV-infected adipose tissue and depletion of adipose-derived stem cells, possibly due to exhaustion following sustained adipocyte death. Genetic analysis revealed that adipose tissue from HIV+ group had increased immune activation, mitochondrial toxicity, chronic inflammation, progressive fibrosis and adipocyte dysfunction (e.g. insulin resistance, inhibited adipocyte differentiation and accelerated apoptosis). Of note, both triglyceride synthesis and lipolysis were inhibited in adipose tissue from patients with HIV.ConclusionsOur findings provide important insights into the pathogenesis of HIV-associated lipodystrophy, suggesting that fat redistribution may critically depend on adipocytes’ sensitivity to drug-induced mitochondrial toxicity, which may lead either to atrophy or metabolic complications.

Effects of in ovo feeding of t10,c12-conjugated linoleic acid on hepatic lipid metabolism and subcutaneous adipose tissue deposition in newly hatched broiler chicks

The purpose of this study was to investigate whether in ovo feeding of t10,c12-conjugated linoleic acid (CLA) could regulate hepatic lipid metabolism and decrease lipid accumulation in newly hatched chicks. Three hundred and sixty fertilely specific pathogen-free hatching eggs were selected and randomly divided into 6 groups. On embryonic day 11 of incubation (E11), 0, 1.5, 3.0, 4.5, 6.0, or 7.5 mg t10,c12-CLA were injected into the eggs. The results indicated that in ovo feeding of t10,c12-CLA significantly decreased the subcutaneous adipose tissue (SAT) mass and the relative SAT weight of newly hatched chicks in linear and quadratic manners (P < 0.05). In liver, the levels of triglycerides were reduced linearly and quadratically and total cholesterol were reduced quadratically as the dose of t10,c12-CLA increased (P < 0.05). Meanwhile, the hepatic carnitine palmitoyltransferase-1a (CPT1a) content and polyunsaturated fatty acid proportion were increased quadratically in t10,c12-CLA groups (P < 0.05), accompanied by the decrease of malondialdehyde level and the increase of glutathione peroxidase and total antioxidant capacity activities (P < 0.05). In addition, in ovo feeding of t10,c12-CLA decreased the mRNA expression levels of fatty acid synthase, acetyl-CoA carboxylase 1 in linear and quadratic manners (P < 0.05), and decreased the mRNA expression of adipose triacylglyceride lipase and stearoyl-CoA desaturase significantly in liver (P < 0.05), accompanied by upregulating the mRNA expression of CPT1a quadratically and AMP-activated protein kinase α linearly and quadratically (P < 0.05). In SAT, the mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ) and sterol regulatory element-binding protein-1c were decreased linearly and quadratically (P < 0.05), and the expression of PPARα and CPT1a genes were increased linearly and quadratically as the dose of t10,c12-CLA increased (P < 0.05). In conclusion, our findings demonstrate that in ovo feeding of t10,c12-CLA alleviates lipid accumulation in newly hatched chicks by suppressing fatty acid synthesis and stimulating lipolysis in the liver and inhibiting adipocyte differentiation in subcutaneous adipose tissue.

Comparative Effects of Sulforaphane and Allyl Isothiocyanate on 3T3-L1 Adipogenesis.

Sulforaphane and allyl isothiocyanate, naturally occurring isothiocyanates, have been reported to inhibit adipocyte differentiation, but little is known about how they compare in terms of their potency and mechanism of action. In the present study, we compared the effects of sulforaphane and allyl isothiocyanate on the differentiation of 3T3-L1 preadipocytes. A mixture of insulin, dexamethasone, and 3-isobutyl-1-methylxanthine was used to establish a differentiation medium. We found that, at a concentration as low as one-tenth that of allyl isothiocyanate, sulforaphane reduced triacylglycerol levels, lipid-filled adipocyte quantity, and mRNA and protein levels of CCAAT-enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ). These results suggested that sulforaphane may be a more potent adipocyte differentiation inhibitor than allyl isothiocyanate. Our results may provide insight into possible strategies for the prevention of obesity and related conditions.

Petasin is the main component responsible for the anti-adipogenic effect of Petasites japonicus

Petasites japonicus is one of the most popular edible wild plants in Japan. Many biological effects of P. japonicus have been reported, including anti-allergy, anti-inflammation, and anticancer effects. Although its anti-obesity effect has been reported in several studies, the most important component responsible for this activity has not been fully elucidated. On screening the components that suppress adipocyte differentiation in 3T3-F442A cells, we found that the extract of the flower buds of P. japonicus has anti-adipogenic effect. Among the known major components of P. japonicus, petasin exhibited a potent anti-adipogenic effect at an IC50 value of 0.95 μM. Quantitative analysis revealed that the active component responsible for most of the anti-adipogenic effects of P. japonicus extract is petasin. Petasin suppressed the expression of markers of mature adipocytes (PPARγ, C/EBPα, and aP2). However, as isopetasin and petasol, analogs of petasin, did not exhibit these effects, it indicates that a double bond at the C11–C12 position and an angeloyl ester moiety were essential for the activity. Petasin affected the late stage of adipocyte differentiation and inhibited the expression of lipid synthesis factors (ACC1, FAS, and SCD1). Additionally, it was revealed that petasin could be efficiently extracted using hexane with minimal amount of pyrrolizidine alkaloids, the toxic components. These findings indicate that P. japonicus extract containing petasin could be a promising food material for the prevention of obesity.

Potential Prebiotic and Anti-Obesity Effects of Codium fragile Extract

Polysaccharides from marine algae exhibit beneficial biological activities. In this study, we examined the effect of Codium fragile extract (CFE) on prebiotic and anti-obesity activity through in vitro experiments. CFE increases the growth of specific beneficial microbial populations with concomitant decrease in pathogenic microbes. Further, total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity (DPPH activity) after fermentation with CFE as the carbon source were higher than for glucose as the control. Moreover, CFE inhibited adipocyte differentiation by inducing differentiation-related factors when the induction of 3T3-L1 preadipocytes into adipocytes was induced. Therefore, we suggest that CFE can be used as a prebiotic material with an anti-obesity effect for human health.

High expression of P4HA3 in obesity: a potential therapeutic target for type 2 diabetes.

The aims of the present study were to evaluate the expression of prolyl 4-hydroxylase subunit alpha 3 (P4HA3) in adipocytes and adipose tissue and to explore its effect on obesity and type 2 diabetes mellitus (T2DM). We initially demonstrated that P4HA3 was significantly upregulated in the subcutaneous adipose tissue of obesity and T2DM patients, and its functional roles in adipocyte differentiation and insulin resistance were investigated using in vitro and in vivo models. The knockdown of P4HA3 inhibited adipocyte differentiation and improved insulin resistance in 3T3-L1 cells. In C57BL/6J db/db mice fed with a high fat diet (HFD), silencing P4HA3 significantly decreased fasting blood glucose and triglycerides (TG) levels, with concomitant decrease of body weight and adipose tissue weight. Further analysis showed that P4HA3 knockdown was correlated with the augmented IRS-1/PI3K/Akt/FoxO1 signaling pathway in the adipose and hepatic tissues of obese mice, which could improve hepatic glucose homeostasis and steatosis of mice. Together, our study suggested that the dysregulation of P4HA3 may contribute to the development of obesity and T2DM.

Polysaccharide CM1 from Cordyceps militaris hinders adipocyte differentiation and alleviates hyperlipidemia in LDLR(+/\u2212) hamsters

BackgroundCordyceps militaris is cultured widely as an edible mushroom and accumulating evidence in mice have demonstrated that the polysaccharides of Cordyceps species have lipid-lowering effects. However, lipid metabolism in mice is significantly different from that in humans, making a full understanding of the mechanisms at play critical.MethodsAfter 5 months, the hamsters were weighed and sampled under anesthesia after overnight fasting. The lipid-lowering effect and mechanisms of the polysaccharide CM1 was investigated by cellular and molecular technologies. Furthermore, the effect of the polysaccharide CM1 (100 μg/mL) on inhibiting adipocyte differentiation was investigated in vitro.ResultsCM1, a polysaccharide from C. militaris, significantly decreased plasma total cholesterol, triglyceride and epididymal fat index in LDLR(+/−) hamsters, which have a human-like lipid profile. After 5 months’ administration, CM1 decreased the plasma level of apolipoprotein B48, modulated the expression of key genes and proteins in liver, small intestine, and epididymal fat. CM1 also inhibited preadipocyte differentiation in 3T3-L1 cells by downregulating the key genes involved in lipid droplet formation.ConclusionsThe polysaccharide CM1 lowers lipid and adipocyte differentiation by several pathways, and it has potential applications for hyperlipidemia prevention.

Chlorogenic Acids Inhibit Adipogenesis: Implications of Wnt/β-Catenin Signaling Pathway

In our previous in vitro study, we found that chlorogenic acid (CGA) inhibited adipocyte differentiation and triglyceride (TG) accumulation, but the underlying mechanism is still unclear. Accumulative genetic evidence supports that canonical Wnt signaling is a key modulator on adipogenesis. Methods. In this study, 3T3-L1 cells were induced adipogenic differentiation and then treated with CGA. We investigate the effect of CGA in inhibiting adipogenesis and evaluate its role in modulating Wnt10b (wingless integration1 10b), β-catenin, glycogen synthase kinase-3β (GSK-3β), and peroxisome proliferator-activated receptor γ (PPAR-γ) involved in the Wnt (wingless integration1)/β-catenin signaling pathway. Results. The result showed that after CGA treatment, lipid accumulation and TG level decreased significantly in 3T3-L1 cells, indicating that CGA could inhibit adipogenesis. In addition, CGA repressed the induction of adipocyte differentiation biomarkers as PPAR-γ, adipocyte protein 2 (aP2), fatty acid synthase (FAS), and lipoprotein lipase (LPL), and the secretion of GSK-3β in a dose-dependent manner upregulated the expression of β-catenin and Wnt10b both in gene and protein levels. Moreover, CGA induced phosphorylation of GSK-3β and promoted the accumulation of free cytosolic β-catenin in 3T3-L1 adipocytes. Conclusion. Overall, these findings gave us the implications that CGA inhibits adipogenesis via the canonical Wnt signaling pathway.

Lycopene nanoparticles promotes osteoblastogenesis and inhibits adipogenesis of rat bone marrow mesenchymal stem cells.

Lycopene is a carotenoid and antioxidant with potent singlet oxygen quenching ability that reduces oxidative stress and promotes bone health. However, the cellular mechanisms by which lycopene influences bone metabolism are not known. The present study investigated the effects of lycopene nanoparticles on the differentiation of rat bone marrow-derived mesenchymal stem cells into osteoblasts or adipocytes. In osteogenic medium, lycopene supplementation dose-dependently enhanced osteoblast differentiation, as evidenced by the transcription of Alpl, Runx2, Col1a1, Sp7, and Bglap, higher alkaline phosphatase activity, osteocalcin secretion and extracellular matrix mineralisation seen with Alizarin red S staining, and increased haem oxygenase levels. By contrast, lycopene in adipogenic medium inhibited adipocyte differentiation evidenced by decreases in the transcription of Tnfsf11, Tnfrsf11b, Pparg, Lpl, and Fabp4 and reduced fat accumulation observed by Oil Red O staining. Lycopene nanoparticles may promote bone health and are considered as a potential candidate for the prevention and/or treatment of bone loss conditions.

Myricetin 3-O-β-D-Galactopyranoside Exhibits Potential Anti-Osteoporotic Properties in Human Bone Marrow-Derived Mesenchymal Stromal Cells via Stimulation of Osteoblastogenesis and Suppression of Adipogenesis.

Natural bioactive substances are promising lead compounds with beneficial effects on various health problems including osteoporosis. In this context, the goal of this study was to investigate the effect of myricetin 3-O-β-D-galactopyranoside (M3G), a glycoside of a known bioactive phytochemical myricetin, on bone formation via osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (hBM-MSCs). The hBM-MSCs were induced to differentiate into osteoblasts and adipocytes in the presence or absence of M3G and the differentiation markers were analyzed. Osteoblastogenesis-induced cells treated with M3G exhibited stimulated differentiation markers: cell proliferation, alkaline phosphatase (ALP) activity, and extracellular mineralization. In terms of intracellular signaling behind the stimulatory effect of M3G, the expression of RUNX2 and osteopontin transcription factors were upregulated. It has been shown that M3G treatment increased the activation of Wnt and BMP as a suggested mechanism of action for its effect. On the other hand, M3G treatment during adipogenesis-inducement of hBM-MSCs hindered the adipogenic differentiation shown as decreased lipid accumulation and expression of PPARγ, SREBP1c, and C/EBPα, adipogenic transcription factors. In conclusion, M3G treatment stimulated osteoblast differentiation and inhibited adipocyte differentiation in induced hBM-MSCs. Osteoblast formation was stimulated via Wnt/BMP and adipogenesis was inhibited via the PPARγ pathway. This study provided necessary data for further studies to utilize the therapeutic potential of M3G against osteoporosis via regulation of bone marrow stromal cell differentiation.

Comparative Effects of Luteolin and Quercetin on Adipogenesis in 3T3-L1 Cells

Purpose: Quercetin has been reported as a more potent inhibitor of fat accumulation than other flavonoids. However, little information is available regarding the strength and mechanism of the repressive action of luteolin on fat accumulation. Therefore, the aim of the present study was to evaluate the comparative effects of luteolin and quercetin on the differentiation of 3T3-L1 preadipocytes into mature adipocytes. Methods: 3T3-L1 preadipocytes were differentiated by treatment with insulin, dexamethasone, and 3-isobutyl-1-methylxanthine in the presence of luteolin or quercetin. Alterations in triacylglycerol (TG) levels, lipid-filled adipocyte quantity, and the mRNA and protein expression levels of CCAAT-enhancer-binding protein α (C/EBPα) and peroxisome proliferator–activated receptor γ (PPARγ) were measured. Results: Both luteolin and quercetin reduced TG levels, the number of lipid-filled adipocytes, and the mRNA expression levels of C/EBPα and PPARγ; however, these effects occurred with lower concentrations of luteolin than quercetin. Conclusions: These results suggest that luteolin may be more potent than quercetin in inhibiting adipocyte differentiation. These effects may be explained by differences in the inhibitory effects of the two compounds on C/EBPα and PPARγ expression. This study suggests that luteolin might be a beneficial dietary supplement for obesity and lifestyle-related diseases.

Hop2 interacts with the transcription factor CEBPα and suppresses adipocyte differentiation

CCAAT enhancer binding protein (CEBP) transcription factors (TFs) are known to promote adipocyte differentiation; however, suppressors of CEBP TFs have not been reported thus far. Here, we find that homologous chromosome pairing protein 2 (Hop2) functions as an inhibitor for the TF CEBPα. We found that Hop2 mRNA is highly and specifically expressed in adipose tissue, and that ectopic Hop2 expression suppresses reporter activity induced by CEBP as revealed by DNA transfection. Recombinant and ectopically expressed Hop2 was shown to interact with CEBPα in pull-down and coimmunoprecipitation assays, and interaction between endogenous Hop2 and CEBPα was observed in the nuclei of 3T3 preadipocytes and adipocytes by immunofluorescence and coimmunoprecipitation of nuclear extracts. In addition, Hop2 stable overexpression in 3T3 preadipocytes inhibited adipocyte differentiation and adipocyte marker gene expression. These in vitro data suggest that Hop2 inhibits adipogenesis by suppressing CEBP-mediated transactivation. Consistent with a negative role for Hop2 in adipogenesis, ablation of Hop2 (Hop2−/−) in mice led to increased body weight, adipose volume, adipocyte size, and adipogenic marker gene expression. Adipogenic differentiation of isolated adipose-derived mesenchymal stem cells showed a greater number of lipid droplet–containing colonies formed in Hop2−/− adipose-derived mesenchymal stem cell cultures than in wt controls, which is associated with the increased expression of adipogenic marker genes. Finally, chromatin immunoprecipitation revealed a higher binding activity of endogenous CEBPα to peroxisome proliferator–activated receptor γ, a master adipogenic TF, and a known CEBPα target gene. Therefore, our study identifies for the first time that Hop2 is an intrinsic suppressor of CEBPα and thus adipogenesis in adipocytes.