To study effects of arachidonic acid (AA) on the growth and differentiation of rat adipocytes, a cells culture system of rat primary preadipocytes was established. The cells treated by different concentration of AA supplemented based on DMEM medium containing 10% fetal bovine serum. Cell proliferation was measured by trypan blue exclusion and methyl thiazolyl tetrazolium (MTT) assay method. Hoechst33342 fluorescence staining observed AA induced morphological changes. Oil Red O staining extraction assay assess the degree of adipogenesis and differentiation, and cyclooxygenases-2(COX-2) mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that rat preadipocytes treated with 120 μmol/L AA for 24-72 hours remarkably promoted the cells proliferation compared with control, 160 μmol/L AA treated for 48 hours could induce apoptosis of preadipocytes. 40, 80 μmol/L AA decreased the fat content in cells at 72 hours, and 40 μmol/L AA significantly up-regulated the expression of COX-2 mRNA at 24 hours. This results indicate that AA regulate adipocytes proliferation and differentiation depended on treatment time and concentration. 40-80 μmol/L AA maybe useful to control body fat, which may be associated with the increase of COX-2 mRNA.

To study the role of BAMBI in adipogenesis, we constructed lentivirus interfering vector targeting on porcine BAMBI, packaged and infected the porcine preadipocyte. The differentiation state of preadipocyte was detected by Oil Red O staining and Oil Red O extraction assay and the expression levels of adipogenic marker genes were detected by Real-time qPCR and Werstern bloting. Results show that BAMBI expression was significant decreased after lentivirus infection, which was repressed more than 60% by shRNA2. Moreover, knockdown BAMBI increased the lipid accumulation of porcine preadipocyte and improved the expression of PPARγ (peroxisome proliferator-activated receptorγ) and ap2 (adipocyte protein 2). In summary, these data indicated that BAMBI inhibited adipocyte differentiation by facilitating the phosphorylation of ERK1/2.
Adipocytes ; cytology ; Adipogenesis ; Animals ; Cell Differentiation ; Membrane Proteins ; metabolism ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; PPAR gamma ; metabolism ; Phosphorylation ; Swine

To clarify the function and molecular mechanism of miR-155 in myogenic differentiation of C2C12, we constructed adenovirus over-expression vector of miR-155, then C2C12 cells were infected by adenovirus and induced myogenic differentiation. First, we observed the morphology of C2C12 after differentiation. Then the mRNA and protein expressions of myogenic markers (MyoD, MyoG and MyHC) were detected by qPCR and western blotting. Subsequently, the dual luciferase reporter gene assay was carried out to validate putative target gene (TCF4) of miR-155. Meanwhile, mRNA level of TCF4 was analyzed after over-expressing miR-155. The results show that over-expressed miR-155 reduced myotubes formation. Moreover, the mRNA and protein expression of MyoG and MyHC decreased significantly (P < 0.01). Further research demonstrated miR-155 bound the one (4532-4538) of three putative sites (1487-1493,1516-1522, 4532-4583) of TCF4 by luciferase reporter gene assay and the mRNA level of TCF4 decreased notably (P < 0.05). The data suggest that miR-155 inhibited myogenic differentiation of C2C12 through targeted TCF4.
Animals ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; genetics ; Cell Differentiation ; Cell Line ; Genetic Vectors ; Mice ; MicroRNAs ; genetics ; Myoblasts ; cytology ; Myogenin ; genetics ; metabolism ; Myosin Heavy Chains ; genetics ; metabolism ; RNA, Messenger ; genetics ; Transcription Factor 4

To explore the effect of chronic high dose of insulin on lipolysis in porcine adipocytes and the underlying molecular regulation mechanisms, we cultured primary porcine adipocytes and incubated them with different concentrations of insulin (0, 200, 400, 800, 1600 nmol/L) for 24-96 h in the absence or presence of specific protein kinase A (PKA) inhibitor or extracellular signal-related kinase (ERK) inhibitor. Then, we measured the glycerol release into the culture media as an indicator of the lipolysis, and observed the lipid accumulation morphology by phase-contrast microscopy. Further, we analyzed the gene expressions of perilipin A and peroxisome proliferator-activated receptor-gamma 2 (PPAR gamma 2) with semi-quantitative RT-PCR and Western blotting, respectively. The results showed that chronic high dose of insulin stimulated lipolysis in differentiated porcine adipocytes in a dose- and time-dependent manner, and significantly attenuated the lipolytic response to isoprenaline. Meanwhile, the protein and mRNA expressions of PPAR gamma 2 and perilipin A were significantly reduced. In addition, both PKA and ERK inhibitors significantly suppressed insulin-stimulated lipolysis, however, only ERK inhibitor reversed the insulin-induced down-regulation of perilipin A. These findings imply that chronic high dose of insulin stimulates lipolysis in porcine adipocytes by repressing perilipin A, which is involved in ERK pathway.
Adipocytes ; cytology ; drug effects ; metabolism ; Animals ; Carrier Proteins ; Dose-Response Relationship, Drug ; Down-Regulation ; drug effects ; Insulin ; pharmacology ; Lipolysis ; drug effects ; Perilipin-1 ; Phosphoproteins ; metabolism ; Swine

In order to construct recombinant adenovirus vector expressing Suppressor of cytokine signaling 3 (SOCS3) and obtain infectious adenoviral particles, SOCS3 gene was amplified from plasmid pcDNA3-SOCS3 and subcloned into the adenovirus shuttle plasmid pAdTrack-CMV. After sequence confirmation, the recombinant shuttle plasmid pAdTrack-CMV-SOCS3 was linearized by Pme I, and then transformed into BJ5183 competent cell, the recombinant plasmid pAd-SOCS3 was obtained by homologous recombination between pAdTrack-CMV-SOCS3 and the adenoviral backbone plasmid pAdEasy-1 in BJ5183. The pAd-SOCS3 was linearized by Pac I and transfected into HEK293 cells via liposome. The recombinant adenovirus was packaged and amplified in HEK293 cells. After purifying, virus titer was determined by tissue culture infectious dose 50 (TCID50). Using the recombinant adenoviruses to infect porcine primary adipocytes, the expression of green fluorescent protein (GFP) was observed by fluorescent microscopy, and SOCS3 gene was identified by RT-PCR and Western blotting. Restriction enzyme and PCR analysis demonstrated that the recombinant adenovirus vector was constructed correctly, and the virus titer reached 1.2x10(9) PFU/mL. The result of RT-PCR and Western blotting showed that SOCS3 mRNA and protein expression was remarkably increased in porcine primary adipocytes infected with recombinant adenovirus. In conclusion, this study successfully constructed the recombinant adenovirus containing SOCS3 gene, and can be helpful for further research on the function of SOCS3.
Adenoviridae ; genetics ; metabolism ; Adipocytes ; metabolism ; Animals ; Cloning, Molecular ; Green Fluorescent Proteins ; biosynthesis ; genetics ; HEK293 Cells ; Humans ; RNA, Messenger ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Suppressor of Cytokine Signaling 3 Protein ; Suppressor of Cytokine Signaling Proteins ; biosynthesis ; genetics ; Swine ; Transfection

To evaluate the influence of Wnt/beta-catenin signal pathway on the porcine adipose tissue development and explore the mechanism, we detected the mRNA expression of Wnt/beta-catenin signal pathway related genes: beta-catenin, GSK3beta, Fzl and adipogenic transcription factors: PPARy, C/EBPalpha and early differentiation marker gene LPL with semi-quantitative (SQ) RT-PCR method. Immunohistochemical method (IHC) was applied to qualitatively measure the sequential expression of beta-catenin protein. The results of SQ RT-PCR showed that beta-catenin highly expressed at the first day after birth, then decreased to a low plateau after 60 days, the expression of GSK3beta and Fzl also decreased with the development process of the porcine adipose tissue development. However, the sequential expression of PPARgamma, C/EBPalpha, LPL appeared to be an opposite manner and kept at a high level after 60 days. The result of IHC showed that the expression of beta-catenin protein was strong in nucleus and cytoplasm at the first day after birth, then tended to decline with the process of adipose tissue development and could be only found in cytoplasm after 30-day old. These results suggest that beta-catenin plays an important role in the undifferentiated state maintenance of preadipocytes and the inhibition of porcine adipose tissue development, the mechanism maybe due to its regulation function on the adipogenic transcription factors PPARy, C/EBPalpha and early differentiation marker gene LPL.
Adipocytes ; metabolism ; Adipose Tissue ; growth & development ; Animals ; Gene Expression Regulation, Developmental ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Signal Transduction ; genetics ; Swine ; Transcription Factors ; Wnt Proteins ; genetics ; beta Catenin ; biosynthesis ; genetics

Swine is an ideal model for diabetes studies. Insulin and insulin resistance are closely related with diabetes. To investigate the effect of SOCS-3 in insulin resistance, porcine primary adipocyte was treated with insulin (100 nmol/L) and dexamethasone (300 nmol/L) to induce insulin resistance. The simi-quantitative PCR results suggested that insulin increased GLUT4, PPARgamma and SOCS-3 gene expression in primary culture porcine adipocytes and no change of OB gene expression. Under insulin resistance conditions, SOCS-3 and OB gene expression were up-regulated, whereas GLUT4 and PPARgamma gene expression were down-regulated in primary porcine adipocytes. The overexpression of PPARgamma gene resulted in the increase of GLUT4 expression by insulin. Different expression levels of SOCS-3 determined the inhibitory effects of insulin signaling. Induction of insulin resistance by dexamethasone was not only due to inhibition of glucose transportation, but also repression of insulin signaling. SOCS-3 might be a potential gene to block the insulin resistance.
Adipocytes ; cytology ; metabolism ; Animals ; Cells, Cultured ; Dexamethasone ; pharmacology ; Glucose Transporter Type 4 ; biosynthesis ; genetics ; Insulin ; pharmacology ; Insulin Resistance ; Leptin ; biosynthesis ; genetics ; PPAR gamma ; biosynthesis ; genetics ; Suppressor of Cytokine Signaling 3 Protein ; Suppressor of Cytokine Signaling Proteins ; biosynthesis ; genetics ; Swine

We demonstrated the effect of resveratrol on porcine primary preadipocytes apoptosis, to study the intracellular molecular mechanism. Porcine primary preadipocyte was treated with different concentration of resveratrol (0 micromol/L, 50 micromol/L, 100 micromol/L, 200 micromol/L, 400 micromol/L). We used optical microscope and fluorescence microscope to observe morphological changes during apoptosis after Hoechst 33258 Fluorescent dyes staining; and RT-PCR and Western blotting to measure the expression of apoptosis-associated gene sirt1, caspase-3, bcl-2, bax, p53, NF-kappaB. Primary preadipocyte apoptosis was apparent, accompanied by reduced cell volume, chromatin condensation, and nuclear shrinkage. Compared to the control and low concentration group, high dose group (200 micromol/L) significantly increased the ratio of primary preadipocyte apoptosis. The expression of sirt1, caspase-3, and bax was up-regulated markedly in response to resveratrol; in contrast, apoptotic inhibitor bcl-2, p53, NF-kappaB down-regulated. We further proved fact that resveratrol can specifically promote the activity of sirt1; moreover, activated sirt1 modulates the activity of caspase-3 and bcl-2 family, involving in transcriptional regulation of p53 and NF-kappaB through antagonizing factor-induced acetylation. Taken together, our data established resveratrol as new regulator in porcine primary preadipocyte apoptosis via activating the expression of sirt1, modulating activity of apoptotic-associated factor.
Adipocytes ; cytology ; Adipogenesis ; Animals ; Antioxidants ; pharmacology ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cells, Cultured ; Sirtuin 1 ; metabolism ; Stilbenes ; pharmacology ; Swine

The Forkhead box O1 (FoxO1) transcription factor governs muscle growth, metabolism and cell differentiation. However, its role in myoblast differentiation is unclear. To study the biological function of FoxO1 during differentiation in porcine primary myoblast, we constructed stably FoxO1 over-expressed porcine myoblast mediated by liposome and adopted morphological observation, quantitative real-time RT-PCR and Western blotting methods to analyze FoxO1 and early and late myogenic regulation factors MyoD and myogenin expression. During differentiation the mRNA level of FoxO1 was significantly increased. However, the total protein did not change but the phosphorylation of FoxO1 was upregulated. Furthermore, overexpression of FoxO1 in porcine myoblast decreased MyoD and myogenin mRNA, whereas MyoD protein changed little and myogenin was significantly suppressed (P < 0.05). These results indicated that FoxO1 delays and negatively regulates the porcine myoblast differentiation. Moreover, FoxO1 may play a critical role in muscle fiber-type specification through the inhibition of myogenic regulation factors.
Animals ; Animals, Newborn ; Cell Differentiation ; genetics ; Cells, Cultured ; Forkhead Transcription Factors ; biosynthesis ; genetics ; Muscle, Skeletal ; cytology ; metabolism ; Myoblasts ; cytology ; metabolism ; RNA, Messenger ; biosynthesis ; genetics ; Swine

Leptin, a cytokine predominantly secreted from fat tissue, plays an important role in regulating organism energy balance. Leptin can stimulate lipolysis, but the mechanism is unclear. In order to study the molecular mechanism of leptin stimulating lipolysis, we systemically studied the mRNA expression of key lipolytic enzymes. Morphological observation, Oil Red O staining and RT-PCR were used to identify pig primary adipocytes; commercial kits were used to measure the glycerol and FFA release; Semiquantitative RT-PCR was used to detect the mRNA expression of key lipolytic enzymes. The results showed that 100 nmol/L leptin up-regulated the mRNA expression of ATGL, TGH-2, HSL, MGL and LPL (P<0.01), but down-regulated the Perilipin mRNA expression (P<0.01). At the same time, leptin promoted the glycerol release in a dose dependent manner (P<0.01), but had no effect on the FFA release (P>0.05). These indicate that leptin may mainly stimulate lipolysis in pig primary adipocytes by up-regulating the expression of ATGL, MGL, LPL and down-regulating the expression of Perilipin. The unchanged FFA release may be resulted from Leptin promoting UCPs mRNA expression and increasing FFA expenditure.
Adipocytes ; cytology ; enzymology ; metabolism ; Animals ; Animals, Newborn ; Cells, Cultured ; Leptin ; pharmacology ; Lipase ; genetics ; metabolism ; Lipolysis ; drug effects ; Male ; Monoacylglycerol Lipases ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Swine