• Journal of Life Science
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• v.17 no.1 s.81
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• pp.56-63
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• 2007

Insulin stimulates the fusion of intracellular vesicles containing glucose transporter 4 (GLUT4) with plasma membrane in adipocytes and muscle cells. Here we show that adipocyte differentiation results in enhanced insulin sensitivity of glucose uptake. On the other hand, glucose uptake in response to platelet-derived growth factor (PDGF) stimulation was markedly reduced by adipocyte differentiation. Expression level of insulin receptor and caveolin-1 was dramatically increased during adipocyte differentiation. Adipocyte differentiation caused :ilightly enhanced activation of acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt) by insulin stimulation. However, activation of Akt by PDGF stimulation was largely reduced. Activation of ERK was not detected in both fibroblasts and adipocytes after stimulation with insulin. PDGF-dependent activation of ERK was reduced by adipocyte differentiation. Insulin-dependent glucose uptake was abrogated by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, in both fibroblasts and adipocytes. Also disassembly of caveolae structure by $methyl-\beta-cyclodextrin$ caused impairment of Akt activation and glucose uptake. Finally, insulin receptor, Akt, SH2-domain-containing inositol 5-phosphatase 2 (SHIP2), and regulatory subunit of PI3K are localized at lipid raft domain and the translocation was facilitated upon insulin stimulation. Given these results, we suggest that lipid raft provide proper site for insulin action for glucose uptake.

• BMB Reports
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• v.42 no.6
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• pp.338-343
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• 2009

The Wnt/$\beta$-catenin signaling pathway alters adipocyte differentiation by inhibiting adipogenic gene expression. $\beta$-catenin plays a central role in the Wnt/$\beta$-catenin signaling pathway. In this study, we revealed that tumour necrosis factor-$\alpha$ (TNF-$\alpha$), a potential negative regulator of adipocyte differentiation, inhibits porcine adipogenesis through activation of the Wnt/$\beta$-catenin signaling pathway. Under the optimal concentration of TNF-$\alpha$, the intracellular $\beta$-catenin protein was stabilized. Thus, the intracellular lipid accumulation of porcine preadipocyte was suppressed and the expression of important adipocyte marker genes, including peroxisome proliferator-activated receptor-$\gamma$ (PPAR$\gamma$) and CCAAT/enhancer binding protein-$\alpha$ (C/EBP$\alpha$), were inhibited. However, a loss of $\beta$-catenin in porcine preadipocytes enhanced the adipogenic differentiation and attenuated TNF-$\alpha$ induced anti-adipogenesis. Taken together, this study indicated that TNF-$\alpha$ inhibits adipogenesis through stabilization of $\beta$-catenin protein in porcine preadipocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.3
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• pp.432-439
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• 2007

Thiazolidinediones (TZDs) act as potent activators of the adipose differentiation program in established preadipose cell lines. TZD's have also been investigated in diabetic patients and reported to act as PPAR-${\gamma}$ ligands. In this report, the effects of TZDs on the differentiation pathway of myoblasts have been investigated. C2C12 mouse myoblasts were grown in Dulbecco's Modified Eagles medium for 4-5 days until they reached almost 100% confluency. Post-confluent cells (day 0) were further exposed to adipogenic induction medium along with TZDs for 48 hours. Thereafter, cells were exposed only to TZDs every 48 h until day 10. The control was provided with differentiation medium without any treatment. Alterations in the cells during the differentiation programme were analyzed on the basis of fusion index, oil-red-o staining, adipocyte index, adipocyte stain uptake measurement, immuno-histochemistry and western blotting. Exposure of C2C12 mouse myoblasts to TZDs prevented the expression of myosin heavy chain with parallel increase in the expression of C/EBP-${\alpha}$ and PPAR-${\gamma}$ and acquisition of adipocyte morphology, thus abolishing the formation of multinucleated myotubes. TZDs exert their adipogenic effects only in non-terminally differentiated myoblasts; myotubes were insensitive to the compound. Continuous exposure (at least 4-5 doses) to inducers after the growth arrest was essential to provide a sustained environment to the cells converting to fully matured adipoctyes. The results indicate that TZDs specifically converted the differentiation pathway of myoblasts into that of adipoblasts.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1551-1558
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• 2008

The mammalian cellular retinoic acid-binding proteins, CRABP-I and CRABP-II, bind retinoic acid which acts as an inducer of differentiation in several biological systems. To investigate a possible role for CRABP-II in bovine adipogenesis, we have cloned bovine CRABP-II cDNA and the coding region for CRABP-I. The predicted amino acid sequences of CRABP-II were highly conserved among several animal species (human, mouse, and rat at 97%, 93%, and 93%, respectively). The expression pattern of bovine CRABP-II was examined in greater details by applying RT-PCR to various bovine tissues. CRABP-II mRNA was expressed in most adipose-containing tissues. Moreover, the expression of CRABP-I and -II mRNA dramatically increased during the differentiation of adipocytes from bovine intramuscular fibroblast-like cells. The effects of retinoic acid on adipocyte differentiation of bovine intramuscular fibroblast-like cells were concentration-dependent. Retinoic acid activated the formation of lipid droplets at a level of 1 nM, whereas inhibition was observed at a level of $1{\mu}M$. CRABP-I gene was up-regulated and CRABP-II gene down-regulated by retinoic acid during adipocyte differentiation. These results suggest that CRABPs may play an important role in the regulation of intracellular retinoic acid concentrations during adipogenesis.

• Natural Product Sciences
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• v.24 no.4
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• pp.235-240
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• 2018

Betula platyphylla var. japonica (Betulaceae), also known as Asian white birch, is an endemic medicinal tree, the bark of which has been used in Chinese traditional medicine for the treatment of various inflammatory diseases. In our continuing search for bioactive compounds from Korean natural resources, a phytochemical investigation of the bark of B. platyphylla var. japonica led to the isolation of 7-oxo-${\beta}$-sitosterol (1) and soyacerebroside I (2) from its ethanol extract as main components by liquid chromatography (LC)/mass spectrometry (MS)-based analysis. The structures of isolates were identified by comparison of $^1H$ and $^{13}C$ nuclear magnetic resonance spectroscopic data and physical data with the previously reported values and LC/MS analyses. To the best of our knowledge, this is the first study to demonstrate that the isolated compounds, 7-oxo-${\beta}$-sitosterol and soyacerebroside I, were isolated in B. platyphylla var. japonica. We examined the effects of the isolates on the regulation of adipocytes and osteoblast differentiation. These isolates (1 and 2) produced fewer lipid droplets compared to the untreated negative control in Oil Red O staining of the mouse mesenchymal stem cell line without altering the amount of alkaline phosphatase staining. The results demonstrated that both compounds showed marginal inhibitory effects on adipocyte differentiation but did not affect osteoblast differentiation.

• Journal of Animal Science and Technology
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• v.62 no.6
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• pp.854-863
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• 2020

This study was aimed to investigate the inhibitory effects of Porphyra dentata (P. dentata) extract on the adipogenesis of 3T3-L1 cells and evaluate its anti-obesity effect. The proliferation of 3T3-L1 cells and differentiation of adipocytes under treatment of P. dentata extract was examined by measuring the cell viability using alamarBlue assay and lipid droplets by Oil Red O staining. Results showed that P. dentata extract has no cytotoxicity effect and lipid droplets formation decreased in a concentration-dependent manner in 3T3-L1 cells. It has been confirmed that transcription factors affecting lipid accumulation and anti-adipogenic effects during cell differentiation are linked to P. dentata extract. We observed that P. dentata shows lowering the mRNA expression of peroxisome proliferator-activated receptor γ2 (PPARγ2), CCAAT/enhancer binding protein α (C/EBPα) that adipogenesis-associated key transcription factors and inhibiting adipogenesis in the early stages of differentiation. Treating the cells with P. dentata did not only suppressed PPARγ2 and C/EBPα but also significantly decreased the mRNA expression of adiponectin, Leptin, fatty acid synthase, adipocyte protein 2, and Acetyl-coA carboxylase 1. Overall, the P. dentata extract demonstrated inhibitory property in adipogenesis, which has a potential effect in anti-obesity in 3T3-L1 cells.

• Animal Bioscience
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• v.35 no.2
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• pp.155-165
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• 2022

Objective: This study was performed to examine whether the porcine glutamic-oxaloacetic transaminase 1 (GOT1) gene has important functions in regulating adipocyte differentiation. Methods: Porcine GOT1 knockout and overexpression vectors were constructed and transfected into the mouse adipogenic 3T3-L1 cells. Lipid droplets levels were measured after 8 days of differentiation. The mechanisms through which GOT1 participated in lipid deposition were examined by measuring the expression of malate dehydrogenase 1 (MDH1) and malic enzyme (ME1) and the cellular nicotinamide adenine dinucleotide phosphate (NADPH) content. Results: GOT1 knockout significantly decreased lipid deposition in the 3T3-L1 cells (p<0.01), whereas GOT1 overexpression significantly increased lipid accumulation (p<0.01). At the same time, GOT1 knockout significantly decreased the NADPH content and the expression of MDH1 and ME1 in the 3T3-L1 cells. Overexpression of GOT1 significantly increased the NADPH content and the expression of MDH1 and ME1, suggesting that GOT1 regulated adipocyte differentiation by altering the NADPH content. Conclusion: The results preliminarily revealed the effector mechanisms of GOT1 in regulating adipose differentiation. Thus, a theoretical basis is provided for improving the quality of pork and studies on diseases associated with lipid metabolism.

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.934-953
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• 2021

Ciglitazone is a member of the thiazolidinedione family, and specifically binds to peroxisome proliferator-activated receptor-γ (PPARγ), thereby promoting adipocyte differentiation. We hypothesized that ciglitazone as a PPARγ ligand in the absence of an adipocyte differentiation cocktail would increase adiponectin and adipogenic gene expression in bovine satellite cells (BSC). Muscle-derived BSCs were isolated from six, 18-month-old Yanbian Yellow Cattle. The BSC were cultured for 96 h in differentiation medium containing 5 µM ciglitazone (CL), 10 µM ciglitazone (CM), or 20 µM ciglitazone (CH). Control (CON) BSC were cultured only in a differentiation medium (containing 2% horse serum). The presence of myogenin, desmin, and paired box 7 (Pax7) proteins was confirmed in the BSC by immunofluorescence staining. The CL, CM, and CH treatments produced higher concentrations of triacylglycerol and lipid droplet accumulation in myotubes than those of the CON treatment. Ciglitazone treatments significantly increased the relative expression of PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα), C/EBPβ, fatty acid synthase, stearoyl-CoA desaturase, and perilipin 2. Ciglitazone treatments increased gene expression of Pax3 and Pax7 and decreased expression of myogenic differentiation-1, myogenin, myogenic regulatory factor-5, and myogenin-4 (p < 0.01). Adiponectin concentration caused by ciglitazone treatments was significantly greater than CON (p < 0.01). RNA sequencing showed that 281 differentially expressed genes (DEGs) were found in the treatments of ciglitazone. DEGs gene ontology (GO) analysis showed that the top 10 GO enrichment significantly changed the biological processes such as protein trimerization, negative regulation of cell proliferation, adipocytes differentiation, and cellular response to external stimulus. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that DEGs were involved in the p53 signaling pathway, PPAR signaling pathway, biosynthesis of amino acids, tumor necrosis factor signaling pathway, non-alcoholic fatty liver disease, PI3K-Akt signaling pathway, and Wnt signaling pathway. These results indicate that ciglitazone acts as PPARγ agonist, effectively increases the adiponectin concentration and adipogenic gene expression, and stimulates the conversion of BSC to adipocyte-like cells in the absence of adipocyte differentiation cocktail.

• The Journal of Korean Medicine
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• v.31 no.2
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• pp.158-166
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• 2010

Objective: It has been reported that Polygonati rhizoma (Pr) has anti-hyperglycemia, anti-triglycemia, anti-diabetic, and anti-tumor activity. Total extract of Pr was tested to identify anti-adipogenic activity in 3T3-L1 differentiation and molecular mechanism of Pr in 3T3-L1 differentiation. Methods: Differentiation of 3T3-L1 pre-adipocyte was induced in the presence of Pr extract and kaempferol. The level of lipid accumulation was measured by Oil Red O staining. The expression of genes associated with adipocyte differentiation was measured by RT-PCR. Results: Extract of Pr and its component kaempferol reduced lipid accumulation in 3T3-L1 during adipogenesis and also reduced mRNA levels of genes associated with adipogenesis, such as adipsin, aP2, LPL, SERBP-1c and $PPAR{\gamma}$. Conclusions: In this study, we showed that the molecular mechanism of Pr and kaempferol activity is related to regulation of $PPAR{\gamma}$ expression and activation.

• Journal of Pharmacopuncture
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• v.12 no.2
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• pp.13-20
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• 2009

In this study, the effects of Ganoderma lucidum (GL) on fat metabolism were performed in 3T3-L1 adipocytes. The effects of GL on 3T3-L1 preadipocytes differentiation were also examined. Our results showed that GL decreased the TG content by ORO staining. To elucidate the mechanism of the effects of GL on lowering TG content in 3T3-L1 adipocytes, we examined whether GL modulate the expressions of transcription factors and adipokines related to control of energy expenditure process because adipokines regulate adipocyte mass and increased expenditure may consume much TG in adipocytes. As a result, the expression of C/$EBP{\beta}$, C/$EBP{\delta}$, C/$EBP{\alpha}$, and $PPAR{\gamma}$, genes, which induce the adipose differentiation and adipose-specific FAS, aP2, and adipsin genes, which compose fat formation were decreased. In addition, GL increased the expression of leptin, UCP2, adiponectin in 3T3-L1 adipocytes, resulting in energy homeostasis. In conclusion, GL could regulate transcript factor related to induction of adipose differentiation and control TG content by up-regulation of adipokines related to fat burn.