As a culinary and medicinal herb, rosemary is widely used. The present work aimed to investigate the effects of rosemary extracts on metabolic diseases and the underlying mechanisms of action. Liver cells stably expressing SREBP reporter were used to evaluate the inhibitory effects of different fractions of rosemary extracts on SREBP activity. The obese mice induced by Western-type diet were orally administered with rosemary extracts or vehicle for 7 weeks, the plasma and tissue lipids were analyzed. SREBPs and their target genes were measured by quantitative RT-PCR. We demonstrated that the petroleum ether sub-fraction of rosemary extracts (PER) exhibited the best activity in regulating lipid metabolism by inhibiting SREBPs, while water and n-BuOH sub-fraction showed the SREBPs agonist-effect. After PER treatment, there was a significant reduction of total SREBPs in liver cells. PER not only decreased SREBPs nuclear abundance, but also inhibited their activity, resulting in decreased expression of SREBP-1c and SREBP-2 target genes in vitro and in vivo. Inhibiting SREBPs by PER decreased the total triglycerides and cholesterol contents of the liver cells. In the mice fed with Western-type diet, PER treatment decreased TG, TC, ALT, glucose, and insulin in blood, and improved glucose tolerance and insulin sensitivity. Furthermore, PER treatment also decreased lipid contents in liver, brown adipose tissue, and white adipose tissue. Our results from the present study suggested that petroleum ether fraction of rosemary extracts exhibited the best potential of improving lipid metabolism by inhibiting SREBPs activity.
Alkanes ; chemistry ; Animals ; Cholesterol ; metabolism ; Hepatocytes ; drug effects ; metabolism ; Humans ; Hyperlipidemias ; drug therapy ; genetics ; metabolism ; Insulin ; metabolism ; Insulin Resistance ; Liver ; drug effects ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Petroleum ; analysis ; Plant Extracts ; administration & dosage ; chemistry ; isolation & purification ; Rosmarinus ; chemistry ; Sterol Regulatory Element Binding Protein 1 ; genetics ; metabolism ; Sterol Regulatory Element Binding Protein 2 ; genetics ; metabolism

The aim of the study was to construct a recombinant adenovirus overexpression vector for Sterol Regulatory Element Binding Protein-1 (SREBP-1) of Xinong Saanen dairy goat, and to detect its effect on genes related to fatty acid metabolism in goat mammary epithelial cells, to establish foundation for further study of its roles in metabolism of fatty acid synthesis and lactation. First, we designed primers based on the SREBP-1 gene sequence in GenBank for PCR amplification and inserted the sequence into shuttle vector pAdTrack-CMV. The recombinant plasmid pAdTrack-CMV-SREBP-1 linearized by Pme I was transformed into E. coli BJ5183 competence cell containing the backbone vector pAdEasy-1 to obtain recombinant vector pAd-SREBP-1 by homologous recombination. pAd-SREBP-1 was linearized by Pac I and transfected into HEK 293 cell. Then we infected goat mammary epithelial cells with recombinant adenovirus which was packaged in HEK 293 cell line. The results showed that the recombinant adenovirus vector containing SREBP-1 was successfully constructed, and the titer of virus was 10(9) U/mL. Compared with the control group, mRNA level of SREBP-1 increased by about 15 times after infected for 48 h and 30 times after infected for 72 h. Fatty acid synthase (FASN) and Acetyl-CoA carboxylase (ACC) was upregulated by almost 2 times. The expression level of Peroxisome proliferator activated receptorgamma (PPARgamma) increased by 1.5 times. Liver X receptoralpha (LXRalpha) and Adipose triglyceride lipase (ATGL) upregulated by 1.2 times compared with that of control. But Stearoyl-coenzyme A desaturase (SCD) had no obvious change. In conclusion, SREBP-1 can activate the expression of genes related to fatty acid synthesis in mammary epithelial cells of Xinong Saanen dairy goat, demonstrated a regulatory function on the fatty acid metabolism in goat mammary gland.
Adenoviridae ; genetics ; metabolism ; Animals ; Epithelial Cells ; cytology ; metabolism ; Fatty Acids ; metabolism ; Female ; Gene Expression Regulation ; Goats ; genetics ; HEK293 Cells ; Humans ; Lipid Metabolism ; genetics ; Mammary Glands, Animal ; cytology ; Sterol Regulatory Element Binding Protein 1 ; genetics ; metabolism ; Transfection

OBJECTIVETo investigate the effect of Hepatitis B Virus X Protein (HBx) on the expression of lipid metabolism-related genes and its role in pathogenesis of hepatocyte fatty degeneration.

METHODSHepatitis B Virus X gene eukaryon expression vector pIRES2-eGFP-HBx was transfected into HepG2 cells to establish HepG2/HBx cell model for HBx expression. HepG2 cells transfected with pIRES2-eGFP (HepG2/pIRES2 cell) and non-transfected were used as controls. At 24, 48 and 72 hours after transfection, the expression of green fluorescent protein (GFP) was observed by fluorescence microscope and the triglyceride(TG) content was detected. RT-PCR and Western blot were applied to detect the levels of sterol regulatory element binding protein-1 (SREBP-1), liver x receptor alpha (LXRalpha) mRNA and the levels of HBx, LXRalpha and fatty acid synthase (FAS) protein. At 24, 48 and 72 hours after transfection, the expression of GFP was found in HepG2/HBx and HepG2/pIRES2 cells, and increased gradually. The expression of HBx was detected only in HepG2/HBx cells, and was increased with time after transfection (F = 32.21, P less than 0.01). These suggested successful obtaining of HepG2-HBx cell model for HBx expression.

RESULTSAt 24h, 48h and 72h after transfection, the expression levels of LXRalpha mRNA (0.386+/-0.055, 0.505+/-0.071, 0.649+/-0.058 ) and SREBP-1 mRNA (0.395+/-0.055, 0.548+/-0.047, 0.795+/-0.058), as well as the levels of LXRalpha protein(0.178+/-0.036, 0.263+/-0.047, 0.347+/-0.058) and FAS protein(0.436+/-0.055, 0.608+/-0.053, 0.827+/-0.046) in HepG2-HBx group were dramatically higher than those in the controls at the same time points (all P less than 0.05/0.01), and were gradually increased with time (all P less than 0.05/0.01). A positive correlationship was observed between HBX protein level and the LXRalpha, SREbP-1 mRNA and LXRalpha, FAS protein levels. The difference of TG content between HepG2/HBx group and control groups was not statistically significant (P more than 0.05).

CONCLUSIONSHBx-LXRalpha-SREBP-1/FAS pathway suggested regulating transcription and expression of lipid metabolism-related genes, which might be one of the important molecular mechanism causing hepatocyte fatty degeneration.

Carcinoma, Hepatocellular ; metabolism ; Fatty Acid Synthase, Type I ; metabolism ; Hep G2 Cells ; Humans ; Lipid Metabolism ; genetics ; Liver Neoplasms ; metabolism ; Liver X Receptors ; Orphan Nuclear Receptors ; metabolism ; Sterol Regulatory Element Binding Protein 1 ; metabolism ; Trans-Activators ; genetics ; Transfection

OBJECTIVETo study the effect of SREBP-1c silencing on lipid metabolism and expression of inflammatory chemokines in a NAFLD model with endoplasmic reticulum stress.

METHODNAFLD model was established in L02 cells treated with oleic acid. SREBP-1c expression was inhibited using RNA interference with a p Silencer-1.0-U6-4476 vector. After transfection with p Silencer-1.0-U6-4476 or control vector for 0 h, 24 h, 48 h and 72 h, the extent of fatty degeneration was shown by Oil Red O staining. The mRNA and protein expression of inflammatory chemokine CCL2 and basic fibroblast growth factor-21 (FGF21) were determined by real time PCR and Western blot respectively.

RESULTSSREBP-1c silenced L02 cells showed fat droplets with smaller diameter and attenuated fatty deposition, as compared with control cells. The relative CCL2 mRNA levels in SREBP-1c silencing vector transfected L02 cells were 1.03+/-0.11 for 0 h, 1.11+/-0.21 for 24 h, 0.88+/-0.16 for 48 h, and 1.05+/-0.15 for 72 h, which showed no significant difference as compared with control cells (P>0.05, respectively). In addition, no difference was found between the different time points within the same group (P>0.05). However, CCL2 protein levels in SREBP-1c silenced cells were 1.19+/-0.15, 1.07+/-0.18, 0.48+/-0.14, and 0.05+/-0.24 after transfection for 0 h, 24 h, 48 h, and 72 h respectively, which were significantly downregulated as compared to the control group (P<0.01). And CCL2 protein levels between different time points in SREBP-1c silenced cells were also distinct (P<0.01). The relative FGF21 mRNA levels in SREBP-1c silenced L-02 cells were 1.01+/-0.08, 0.91+/-0.22, 0.98+/-0.20, and 1.02+/-0.12 for 0 h, 24 h, 48 h, and 72 h respectively, which were not statistically different as compared with the corresponding control cells. Statistic difference of FGF21 mRNA levels in SREBP-1c knockdown cells of different time points was not found (P>0.05). In striking contrast, robust down regulation of FGF21 protein in SREBP-1c silenced cells was observed, with 0.81+/-0.05, 0.66+/-0.12, 0.58+/-0.08 and 0.19+/-0.13 after transfection for 0 h, 24 h, 48 h and 72 h respectively, as compared to control group (P<0.01). And differences in FGF21 protein level between different time points in SREBP-1c silenced cells were also demonstrated (P<0.01).

CONCLUSIONSREBP-1c knockdown attenuated fatty deposition in oleic acid treated L02 cells. In addition, silencing of SREBP-1c expression reduced expressions of CCL2 and FGF21 proteins posttranscriptionally, which may play a role in endoplasmic reticulum stress induced inflammatory response in NAFLD.

Cell Line ; Chemokine CCL2 ; metabolism ; Endoplasmic Reticulum Stress ; Fibroblast Growth Factors ; metabolism ; Gene Knockdown Techniques ; Hepatocytes ; metabolism ; Humans ; Lipid Metabolism ; RNA Interference ; Sterol Regulatory Element Binding Protein 1 ; genetics

Obesity is associated with a number of metabolic abnormalities such as type 2 diabetes and has become a major health problem worldwide. In the present study, we investigated the effects of Epimedium koreanum Nakai (Herba Epimedii, HE) and its main constituent icariin on the adipocyte differentiation in 3T3-L1 preadipocytes. HE extract and icariin significantly reduced lipid accumulation and suppressed the expressions of PPARγ, C/EBPα, and SREBP-1c in 3T3-L1 adipocytes. They also inhibited fatty acid synthase (FAS), acyl-Co A synthase (ACS1), and perilipin. Moreover, HE extract and icariin markedly increased the phosphorylation of AMPK. These results indicated that HE extract and icariin can inhibit the adipocyte differentiation through downregulation of the adipogenic transcription factors, suggesting that HE containing icariin may be used as a potential therapeutic agent in the treatment and prevention of obesity.
3T3-L1 Cells ; Adipocytes ; cytology ; drug effects ; metabolism ; Adipogenesis ; drug effects ; Animals ; CCAAT-Enhancer-Binding Protein-alpha ; genetics ; metabolism ; Epimedium ; chemistry ; Flavonoids ; pharmacology ; Lipid Metabolism ; drug effects ; Mice ; PPAR gamma ; genetics ; metabolism ; Plant Extracts ; pharmacology ; Sterol Regulatory Element Binding Protein 1 ; genetics ; metabolism

OBJECTIVETo study the role of S6K1 in the induction of SREBP1c in mouse hepatic cell by high glucose stimulation.

METHODSS6K1 shRNA recombinant adenovirus (S6K1Ax) was injected into tail vein of db/db mice and then hepatic triglycerol content was analyzed. Liver specimen were stained with HE. After transfection with S6K1Ax or pU6Ax, mouse hepatic AML12 cells were treated with high glucose, insulin or glucose and insulin, the expression of mSREBP1c was detected by RT-PCR. S6K1 protein was detected by Western blot.

RESULTSHepatic S6K1 protein in db/db mice was inhibited a week after S6K1Ax injection. Compared with the control group, hepatic triglycerol content of S6K1Ax group was decreased (0.65+/-0.02) mmol/L vs (0.56+/-0.01) mmol/L (t = 4.312, P less than 0.01), hepatocyte fat droplet and vaculor generation were also decreased, fatty liver was improved. The mSREBP1c expression in S6K1Ax transfected cells was lower than that in the control cells (0.03+/-0.01 vs 0.06+/-0.01, t = 5.624, P less than 0.01). Compared with the basal state, SREBP1c expression of both groups was increased on the insulin stimulation, S6K1Ax group was 0.06+/-0.02 (t = 8.452, P less than 0.01) and control group was 0.08+/-0.02 (t = 3.591, P less than 0.05). There is no difference between control and S6K1Ax group by glucose addition (P more than 0.05).

CONCLUSIONS6K1 acts on fatty synthesis by regulating mSREBP1c expression.

Adenoviridae ; genetics ; Animals ; Cell Line ; Fatty Acid Synthases ; genetics ; metabolism ; Gene Expression Regulation ; Glucose ; administration & dosage ; Insulin ; administration & dosage ; Liver ; metabolism ; pathology ; Liver Cirrhosis ; etiology ; metabolism ; pathology ; Mice ; Mice, Inbred Strains ; RNA Interference ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Ribosomal Protein S6 Kinases, 90-kDa ; genetics ; metabolism ; Staining and Labeling ; Sterol Regulatory Element Binding Protein 1 ; genetics ; metabolism ; Transfection ; Triglycerides ; metabolism

Farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. As a metabolic regulator, FXR plays key roles in bile acid and cholesterol metabolism and lipid and glucose homeostasis. Therefore, FXR is a potential drug target for several metabolic syndromes, especially those related to lipidemia disorders. In the present study, we identified small molecule SIPI-7623, a derivative of an extract from Oriental wormwood (Artemisia capillaris), and found that it specifically upregulated the expression of cholesterol-7-alpha-hydroxylase (CYP7A1), downregulated the expression of sterol-regulatory element-binding protein 1c (SREBP-1c) in the liver, and inhibited the expression of ileal bile acid binding-protein (IBABP) in the ileum of rats. We found that inhibition of FXR by SIPI-7623 decreased the level of cholesterol and triglyceride. SIPI-7623 reduced the levels of cholesterol and triglyceride in in vitro HepG2 cell models, ameliorated diet-induced atherosclerosis, and decreased the serum lipid content on rats and rabbits model of atherosclerosis in vivo. Furthermore, SIPI-7623 decreased the extent of atherosclerotic lesions. Our resutls demonstrated that antagonism of the FXR pathway can be employed as a therapeutic strategy to treat metabolic diseases such as hyperlipidemia and atherosclerosis. In conclusion, SIPI-7623 could be a promising lead compound for development of drugs to treat hyperlipidemia and atherosclerosis.
Animals ; Artemisia ; chemistry ; Atherosclerosis ; drug therapy ; genetics ; metabolism ; Cholesterol ; metabolism ; Cholesterol 7-alpha-Hydroxylase ; genetics ; metabolism ; Drugs, Chinese Herbal ; administration & dosage ; Humans ; Hyperlipidemias ; drug therapy ; genetics ; metabolism ; Hypolipidemic Agents ; administration & dosage ; Liver ; drug effects ; metabolism ; Male ; Rabbits ; Rats ; Rats, Sprague-Dawley ; Receptors, Cytoplasmic and Nuclear ; antagonists & inhibitors ; genetics ; metabolism ; Sterol Regulatory Element Binding Protein 1 ; genetics ; metabolism ; Triglycerides ; metabolism

This study investigated the effects of SIRT1 gene knock-out on osteoarthritis in mice, and the possible roles of SREBP2 protein and the PI3K/AKT signaling pathway in the effects. Mice were randomly divided into a normal group and a SIRT1 gene knock-out group (6 mice in each group). In these groups, one side of the knee anterior cruciate ligament was traversed, and the ipsilateral medial meniscus was cut to establish an osteoarthritis model of knee joint. The countralateral synovial bursa was cut out, serving as controls. The knee joint specimens were then divided into four groups: SIRT1control group (group A, n=6); SIRT1osteoarthritis group (group B, n=6); SIRT1control group (group C, n=6); SIRT1osteoarthritis group (group D, n=6). HE staining, Masson staining, Safranin O-Fast Green staining and Van Gieson staining were used to observe the morphological changes in the articular cartilage of the knee. Immunohistochemical staining was employed to detect the expression of SIRT1, SREBP2, VEGF, AKT, HMGCR and type II collagen proteins. SA-β-gal staining was utilized to evaluate chondrocyte aging. The results showed clear knee joint cartilage destruction and degeneration in the SIRT1osteoarthritis group. The tidal line was twisted and displaced anteriorly. Type II collagen was destroyed and distributed unevenly. Compared with the SIRT1osteoarthritis group and SIRT1control group, SIRT1 protein expression was not obviously changed in the SIRT1osteoarthritis group (P>0.05), while the expression levels of the SREBP2, VEGF and HMGCR proteins were significantly increased (P<0.05) and the levels of AKT and type II collagen proteins were significantly decreased (P<0.05). SIRT1 gene knock-out may aggravate cartilage degeneration in osteoarthritis by activating the SREBP2 protein-mediated PI3K/AKT signalling pathway, suggesting that SIRT1 gene may play a protective role against osteoarthritis.
Animals ; Cartilage ; pathology ; Chondrocytes ; metabolism ; Collagen Type II ; metabolism ; Disease Models, Animal ; Humans ; Knee Joint ; metabolism ; pathology ; Mice ; Mice, Knockout ; Oncogene Protein v-akt ; genetics ; Osteoarthritis ; genetics ; pathology ; Phosphatidylinositol 3-Kinases ; genetics ; Signal Transduction ; genetics ; Sirtuin 1 ; genetics ; Sterol Regulatory Element Binding Protein 2 ; biosynthesis ; genetics ; Vascular Endothelial Growth Factor A ; biosynthesis

Postmenopausal women, who have reduced circulating estrogen levels, are more prone to develop obesity and related metabolic diseases than premenopausal women. The absence of safe and effective treatments for postmenopausal obesity has changed the focus to natural products as alternative remedies. Total salvianolic acids (TSA) are the major water-soluble ingredients of Danshen. Salvianolic acid (SA) is the major constituent of the TSA. Salvianolic acids, including TSA and SA, are widely used in traditional Chinese medicine. In the present study, ovariectomized rats and LO2 cells were used to study the effects of salvianolic acids on body weight gain and hepatic steatosis. Salvianolic acids reduced ovariectomy (OVX)-induced body weight gain, attenuated the expressions of hepatic lipogenic genes, such as sterol regulatory element binding protein (SREBP)1, fatty acid synthase (FAS), and stearoyl-CoA desaturase (SCD)1, and decreased the liver triglyceride (TG) and total cholesterol (TC). For the molecular mechanisms, OVX and high glucose-induced phosphorylation of signal transducer and activator of transcription (STAT)-3 was inhibited by salvianolic acids treatment. In LO2 cells, inhibition of STAT-3 by siRNA attenuated the increased expression of SREBP1 and TG induced by high glucose. Salvianolic acids reduced the upregulation of SREBP1 and TG induced by high glucose in LO2 cells. In conclusion, these findings illustrated that salvianolic acids markedly alleviated the lipid metabolism disorders and protected against the postmenopausal obesity. The underlying mechanism was probably associated with the regulation of STAT-3 signaling.
Alkenes ; administration & dosage ; Animals ; Drugs, Chinese Herbal ; administration & dosage ; Female ; Humans ; Lipid Metabolism ; drug effects ; Liver ; drug effects ; metabolism ; Obesity ; drug therapy ; genetics ; metabolism ; Ovariectomy ; Polyphenols ; administration & dosage ; Postmenopause ; drug effects ; genetics ; metabolism ; Rats ; STAT3 Transcription Factor ; genetics ; metabolism ; Salvia miltiorrhiza ; chemistry ; Signal Transduction ; drug effects ; Sterol Regulatory Element Binding Protein 1 ; genetics ; metabolism ; Triglycerides ; metabolism

Hepatic steatosis is common in obese individuals with hyperinsulinemia and is an important hepatic manifestation of metabolic syndrome. Sterol regulatory binding protein-1c (SREBP-1c) is a master regulator of lipogenic gene expression in the liver. Hyperinsulinemia induces transcription of SREBP-1c via activation of liver X receptor (LXR) and specificity protein 1 (Sp1). Cilostazol is an antiplatelet agent that prevents atherosclerosis and decreases serum triglyceride levels. However, little is known about the effects of cilostazol on hepatic lipogenesis. Here, we examined the role of cilostazol in the regulation of SREBP-1c transcription in the liver. The effects of cilostazol on the expression of SREBP-1c and its target genes in response to insulin or an LXR agonist (T0901317) were examined using real-time RT-PCR and western blot analysis on cultured hepatocytes. To investigate the effect of cilostazol on SREBP-1c at the transcriptional level, transient transfection reporter assays and electrophoretic mobility shift assays (EMSAs) were performed. Cilostazol inhibited insulin-induced and LXR-agonist-induced expression of SREBP-1c and its downstream targets, acetyl-CoA carboxylase and fatty acid synthase, in cultured hepatocytes. Cilostazol also inhibited activation of the SREBP-1c promoter by insulin, T0901317 and Sp1 in a luciferase reporter assay. EMSA analysis showed that cilostazol inhibits SREBP-1c expression by repressing the binding of LXR and Sp1 to the promoter region. These results indicate that cilostazol inhibits insulin-induced hepatic SREBP-1c expression via the inhibition of LXR and Sp1 activity and that cilostazol is a negative regulator of hepatic lipogenesis.
Animals ; Cells, Cultured ; Hep G2 Cells ; Hepatocytes/drug effects/*metabolism ; Humans ; Hydrocarbons, Fluorinated/pharmacology ; Insulin/pharmacology ; Lipogenesis ; Mice ; Mice, Inbred C57BL ; Orphan Nuclear Receptors/agonists/*metabolism ; Promoter Regions, Genetic ; Protein Binding ; Rats ; Sp1 Transcription Factor/*metabolism ; Sterol Regulatory Element Binding Protein 1/genetics/*metabolism ; Sulfonamides/pharmacology ; Tetrazoles/*pharmacology