Sterol Regulatory Element Binding Protein-1c mRNA Expression Research Articles

Dimethyloxalylglycine Suppresses SREBP1c and Lipogenic Gene Expressions in Hepatocytes Independently of HIF1A.

Dimethyloxalylglycine (DMOG) is a representative inhibitor of the prolyl hydroxylase domain (PHD), which mediates the degradation of hypoxia-inducible factor-1-alpha (HIF1A). DMOG exerts its pharmacological effects via the canonical pathway that involves PHD inhibition; however, it remains unclear whether DMOG affects lipogenic gene expression in hepatocytes. We aimed to elucidate the effects of DMOG on sterol regulatory element-binding protein-1c (SREBP1c), a master regulator of fatty acid synthesis in hepatocytes. DMOG treatment inhibited SREBP1c mRNA and protein expression in HepG2 and AML12 hepatocytes and reduced the transcript levels of SREBP1c-regulated lipogenic genes. A luciferase reporter assay revealed that DMOG inhibited the transcriptional activity of SREBP1c. Moreover, DMOG suppressed SREBP1c expression in mice liver. Mechanistically, treatment with DMOG enhanced the expression of HIF1A and insulin-induced gene 2 (INSIG2), which inhibits the activation of SREBP1c. However, HIF1A or INSIG2 knockdown failed to reverse the inhibitory effect of DMOG on SREBP1c expression, suggesting a redundant role of HIF1A and INSIG2 in terms of repressing SREBP1c. DMOG did not function through the canonical pathway involving inhibition of SREBP1c by PHD, highlighting the presence of non-canonical pathways that mediate its anti-lipogenic effect.

Studies on the Effect of Piperine on Hepatocyte Nuclear Factor 1 Alpha (HNF-1α) and Sterol Regulatory Element-Binding Protein 1c (SREBP-1c) Levels in High-Fat-Diet and Sucrose-Induced Type 2 Diabetes Mellitus Rats.

Piperine, a naturally occurring compound in black pepper (Piper nigrum), is known for its potential health benefits, including its reported enhancement of insulin sensitivity. However, the precise impact of piperine on hepatocyte nuclear factor 1 alpha (HNF-1α) and sterol regulatory element-binding protein 1c (SREBP-1c), transcription factors for insulin signaling and glucose metabolism in hepatocytes, remains unclear. This study aims to investigate the effect of piperine, compared to metformin, on blood glucose and insulin levels by modifying the expression of hepatic HNF-1α and SREBP-1c in high-fat-diet (HFD) and sucrose-induced type 2 diabetes mellitus (T2DM) rats and in human Chang liver cells. Adult male albino rats were categorized into four groups: group 1 as the control, group 2 as T2DM, group 3 as T2DM rats treated with piperine (40 mg), and group 4 as T2DM rats treated with metformin (50 mg). Fasting blood glucose (FBG) and serum insulin levels were measured using enzyme-linked immunosorbent assay (ELISA), while real-time polymerase chain reaction (RT-PCR) analysis was conducted to assess the mRNA expression of HNF-1α and SREBP-1c. Further, piperine was treated with normal and high glucose-induced Chang liver cells, and gene expression was analysed.Data analysis was performed using one-way analysis of variance (ANOVA), with a significance set at p<0.05. Treatment with piperine led to a notable decrease in blood glucose levels and circulating insulin when compared with T2DM rats (group 2). Additionally, piperine administration resulted in the upregulation of HNF-1α mRNA expression and downregulation of SREBP-1c mRNA levels whose effects were found to be near that of the control and standard drug metformin's effects. In vitro study also confirmed that piperine improved the HNF-1αexpression and reduced the expression of SREBP-1c in Chang liver cells. Our findings suggest that piperine treatment effectively regulates hyperglycemic and hyperinsulinemic insulin resistance in the liver by modulating the expression of HNF-1α and SREBP-1c. Consequently, piperine emerges as a promising candidate for therapeutic intervention in managing T2DM.

Antihyperlipidemic effect of bread fortified with potato peel powder against Triton X-100-induced hyperlipidemia in male albino rats

The present investigation aimed to improve the nutritional and healthy values and evaluate the influence of bread fortified with dried potato peels (BPP) on Triton X-100-induced hyperlipidemia in male albino rats. The findings demonstrated that BPP lowered hepatic triglycerides and total cholesterol while increasing high-density lipoprotein (HDL-C). BPP exhibited potential lipid-lowering and hepatoprotective actions that were generated by the reduction of oxidative damage and preservation of the non-enzymatic and enzymatic antioxidant systems compromised by hyperlipidemic condition. Furthermore, BPP considerably enhanced the mRNA expression of AMPKα (AMP-activated protein kinase-alpha), suppressed the expression of fatty acid synthase (FAS) and acetyl-CoA carboxylase alpha (ACCα), and decreased the mRNA expression of the adipogenic transcription factor SREBP-1c (sterol regulatory element-binding protein-1c), which are essential regulators of hepatocyte lipid metabolism. A histopathological assessment of the liver confirmed the results. In conclusion, this investigation revealed a positive impact of bread fortified with BPP therapy in preventing hyperlipidemia.

The Synergistic Effect of Fluvastatin and IFN-λ on Peripheral Blood Mononuclear Cells of Chronic Hepatitis C Virus (HCV) Patients with IL-28B rs12979860 CC Genotype.

There is a relationship between the life cycle of the hepatitis C virus (HCV) and the synthesis and hemostasis of lipids as well as lipid metabolism and interferon (IFN) regulatory system. This study was aimed to examine the effect of fluvastatin and IFN-ƛ in the expression of mediators involved in lipid metabolism and HCV proliferation in patients with rs12979860 CC polymorphism. Thirteen patients with HCV and five controls with rs1297986CC polymorphism were included in this study. Peripheral blood mononuclear cells (PBMCs) of patients and controls were treated by fluvastatin, IFN-λ or fluvastatin+IFN-λ. Assessment of IL-28B polymorphism, RNA extraction, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed. The mRNA expression of sterol regulatory element-binding protein 1 c (SREBP1c), ATP-binding cassette transporter A1 (ABCA1), diacylglycerol acyltransferase 1 (DGAT1), and HCV core as well as measurement of ABCA1 protein level were evaluated before and after treatment. The results indicated that IFN-λ +fluvastatin acted as an inhibitor in mRNA expression of SREBP1c; while acting as an inducer in the expression of ABCA-1. The results of ABCA1 assay showed a significant increase of this protein after treatment with fluvastatin and IFN-λ compared with untreated cells (p=0.02). Moreover, the mRNA expression of HCV core was suppressed in all experimental groups treated with fluvastatin, IFN-λ or their combination which was more significant after treatment with fluvastatin+IFN-λ (p<0.001). The results of this study demonstrated the significant effect of treatment with fluvastatin+IFN-λ in PBMCs of HCV patients with rs12979860 CC polymorphism. According to the drug resistance of viruses and prevention of virus-induced steatosis in patients with HCV, using regulatory agents of lipid mediators in parallel with current medications could be considered as an effective therapeutic strategy.

The possible antidiabetic effects of vitamin D receptors agonist in rat model of type 2 diabetes.

Vitamin D3 deficiency was found to be tightly linked to many health problems including metabolic syndrome, cancer, cardiovascular diseases, and type 2 diabetes mellitus. In our study, we tested the possible antidiabetic effects of one of vitamin D3 analogs, alfacalcidol, solely or in a combination with metformin on type 2 diabetic rats. Type 2 diabetic model rats were induced by feeding high-fat diet for 4weeks followed by intraperitoneal injection of streptozotocin. In addition to the control group, the diabetic rats were divided into four groups: untreated, metformin-treated, alfacalcidol-treated, and combination-treated group (metformin + alfacalcidol) for 4weeks. The level of fasting blood glucose, fasting serum insulin, homeostatic model of insulin resistance, serum lipid profile, liver enzymes, calcium, phosphorus, and 25-hydroxyvitamin D3 were also determined. Besides, sterol regulatory element binding protein-1c (SREBP-1c) and vitamin D receptors (VDR) gene expression at mRNA and protein levels were evaluated. The level of significance was fixed at P ≤ 0.05 for all statistical tests. Alfacalcidol, solely or combined with metformin, significantly ameliorated glucose homeostasis and lipid profile parameters (P < 0.001) with a neutral effect on calcium and phosphorus levels. Significant downregulation of mRNA expression of SREBP-1c in the liver, white as well as brown adipose tissues (P < 0.001) and different patterns of mRNA expression of VDR gene in pancreas and white adipose tissue were observed in rats treated with alfacalcidol solely or in combination with metformin. Vitamin D3 analogs can modulate glucose parameters and lipid metabolism in a diabetic rat model and it provides additional protective effects when combined with metformin.

Neonatal overfeeding induced glucocorticoid overexposure accelerates hepatic lipogenesis in male rats

BackgroundPostnatal overfeeding activates tissue glucocorticoid (GC) activity by up-regulating 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) and increasing sensitivity to high-fat (HF) diet-induced non-alcoholic fatty liver disease (NAFLD). The present study aimed to evaluate the effects of postnatal overfeeding on GC regulation and lipogenesis in the liver and to observe the impact of GC on hepatocyte lipid metabolism.MethodsIn vivo, Male Sprague-Dawley rat pup litters were adjusted to litter sizes of three (small litter, SL) or ten (normal litter, NL) on postnatal day 3 and then given standard chow from postnatal week 3 (W3) to W13. In vitro, HepG2 cells were stimulated by GC, mifepristone (Mi) or GC + Mi within 48 h, followed by sodium oleate (OA) intervention (or not) for 24 h. Intracellular lipid droplets, triglyceride (TG) concentrations and gene expression related to lipid metabolism were measured in hepatic tissues or HepG2 cells.ResultsIn vivo, weight gain in the body and liver and TG concentrations in the liver were significantly increased in the SL rats compared to the NL rats at W3 and W13 (p < 0.05); mRNA expression of hepatic 11β-HSD1, acetyl-CoA carboxylase 1 (ACC), stearoyl-CoA desaturase-1 (SCD1), fatty acid synthase (FASN) and their nuclear transcription factor, sterol regulatory element binding protein-1c (SREBP-1c) (p < 0.05), was also increased. In vitro, intracellular lipid droplets and TG content in HepG2 cells increased under stimulation with GC or OA (p < 0.05); the increase was more significant following treatment with GC and OA together (p < 0.05). The ACC, SCD1, FASN and SREBP-1c mRNA expression changes were highly similar to the changes in TG content in cells. All the changes induced by GC disappeared when the glucocorticoid receptor (GR) was blocked by Mi.ConclusionsPostnatal overfeeding induced GC overexposure through 11β-HSD1 up-regulation in the liver. GC activated hepatic de novo lipogenesis (DNL) via GR and led to hepatic lipid accumulation, which increased the risk of NAFLD during adulthood.

Silymarin prevents lipid accumulation in the liver of rats with type 2 diabetes via sirtuin1 and SREBP-1c.

In this study, we have investigated whether silymarin intake influences lipid and glycogen content in conjunction with sirtuin1 (SIRT1) and sterol regulatory element-binding protein 1c (SREBP-1c) expressions in liver of type 2 diabetic rat. Thirty-six male Wistar rats were randomly divided into six groups: control groups (C) and diabetic groups (D); the control groups received 60 or 120 mg/kg silymarin (C+S60 or C+S120), and the diabetic groups received 60 or 120 mg/kg silymarin (D+S60 or D+S120) daily for 8 weeks. Serum biochemical parameters, as well as glycogen, lipid and oxidative stress biomarkers, in the liver tissue were measured by spectrophotometric methods. Additionally, SIRT1 and SREBP-1c messenger RNA (mRNA) expressions were evaluated by quantitative polymerase chain reaction. Diabetes caused a significantly increased fasting blood sugar, homeostasis model assessment for insulin resistance, liver total cholesterol and triglyceride (TG) content, which were attenuated after the administration of silymarin. Dietary silymarin caused the improvement of lipid content in the liver of diabetic rats. Moreover, silymarin administration promoted SIRT1, suppressed SREBP-1c mRNA expression, reduced liver nitric oxide and protein carbonyl content, and increased liver glycogen, catalase and glutathione peroxidase activity. Furthermore, histopathological changes were improved in the treated groups. Silymarin administration considerably restored hepatic changes induced by streptozotocin and nicotinamide. The upregulation of SIRT1 mRNA expression by silymarin may be associated with decreased lipid, increased glycogen content and downregulation of the SREBP-1c gene in the liver.

GLP-1 Elicits an Intrinsic Gut–Liver Metabolic Signal to Ameliorate Diet-Induced VLDL Overproduction and Insulin Resistance

Perturbations in hepatic lipid and very-low-density lipoprotein (VLDL) metabolism are involved in the pathogenesis of obesity and hepatic insulin resistance. The objective of this study is to delineate the mechanism of subdiaphragmatic vagotomy in preventing obesity, hyperlipidemia, and insulin resistance. By subjecting the complete subdiaphragmatic vagotomized mice to various nutritional conditions and investigating hepatic de novo lipogenesis pathway, we found that complete disruption of subdiaphragmatic vagal signaling resulted in a significant decrease of circulating VLDL-triglyceride compared with the mice obtained sham procedure. Vagotomy further prevented overproduction of VLDL-triglyceride induced by an acute fat load and a high-fat diet-induced obesity, hyperlipidemia, hepatic steatosis, and glucose intolerance. Mechanistic studies revealed that plasma glucagon-like peptide-1 was significantly raised in the vagotomized mice, which was associated with significant reductions in mRNA and protein expression of SREBP-1c (sterol regulatory element-binding protein 1c), SCD-1 (stearoyl-CoA desaturase-1), and FASN (fatty acid synthase), as well as enhanced hepatic insulin sensitivity. In vitro, treating mouse primary hepatocytes with a glucagon-like peptide-1 receptor agonist, exendin-4, for 48 hours inhibited free fatty acid, palmitic acid treatment induced de novo lipid synthesis, and VLDL secretion from hepatocytes. Elevation of glucagon-like peptide-1 in vagotomized mice may prevent VLDL overproduction and insulin resistance induced by high-fat diet. These novel findings, for the first time, delineate an intrinsic gut-liver regulatory circuit that is mediated by glucagon-like peptide-1 in regulating hepatic energy metabolism.

Effect of transforming growth factor-β1 on HBV replication and antigen synthesis in HepG2.2.15 cells with steatosis

Objective: To investigate the effect of transforming growth factor-β1 (TGF-β1) on HBV replication and protein expression in HepG2.2.15 cells with steatosis, as well as the association of TGF-β1 with suppressor of cytokine signaling-3 (SOCS-3) mRNA and sterol regulatory element-binding protein-1c (SREBP-1c) mRNA during the steatosis of HepG2.2.15 cells. Methods: The cells were divided into HepG2/HepG2.2.15 cell control groups (C1/C2 groups) and HepG2/HepG2.2.15 cell steatosis groups (F1/F2 groups). 5 ng/ml TGF-β1 was added to the two cell systems for intervention to establish TGF-β1 intervention groups (T1/T2 groups) and steatosis+TGF-β1 intervention groups (TF1/TF2 groups). A time-resolved fluorescence analyzer was used to measure HBsAg and HBeAg, and quantitative real-time PCR was used to measure HBV DNA, SOCS-3 mRNA, and SREBP-1 mRNA. A one-way analysis of variance and a factorial analysis were used for the statistical analysis of data. Results: TGF-β1 significantly reduced the level of HBeAg in C2 group (P = 0.034) and the levels of HBsAg (P < 0.001) and HBeAg (P = 0.004) in F2 group. There was an interaction between steatosis and TGF-β1 in inhibiting HBsAg. In addition, TGF-β1 significantly reduced the mRNA expression of SOCS-3 in C1, F1, C2, and F2 groups (P < 0.05) and significantly increased the mRNA expression of SREBP-1c in C1, F1, C2, and F2 groups (P < 0.05), suggesting that there was an interaction between steatosis and TGF-β1 in downregulating the mRNA expression of SOCS-3 and upregulating the mRNA expression of SREBP-1c. Conclusion: TGF-β1 does not affect HBV duplication in HepG2.2.15 cells and can inhibit the expression of HBsAg and HBeAg. TGF-β1 can downregulate the mRNA expression of SOCS-3 and upregulate the mRNA expression of SREBP-1c.

Effect of chitooligosaccharide on hepatic triglyceride metabolism and related mechanisms

To investigate the effect of chitooligosaccharide (COS) on hepatic triglyceride (TG) metabolism and related mechanisms. The LO2 cells treated by 1 mmol/L fatty acid were used as model group, the cells treated by 1 mmol/L fatty acid and 0.5 mg/ml COS were used as COS group, and the untreated cells were used as control group. The TG content in cells was measured. RT-PCR and Western blot were used to measure the mRNA and protein expression of sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), and carnitine palmityl transferase 1A (CPT1A) in each group. Male C57BL/6J mice were randomized into control group, high-fat group, and COS group to receive different treatments. Sixteen weeks later, the liver was harvested for HE and oil red O staining to measure the content of TG in the liver. The t-test or one-way analysis of variance was used for comparison of data between groups, and the SNK method was used for comparison of data between any two groups. The LO2 cells in the model group had an increased number of lipid droplets and an increased TG content, and after COS treatment, the TG content was low. The COS group had significantly lower relative mRNA expression of SREBP-1c and FAS compared with the model group (1.135 ± 0.177 vs 2.322 ± 0.198,F= 60.457,P< 0.01; 1.226 ± 0.150 vs 1.801 ± 0.159,F= 24.753,P< 0.01), while compared with the control group, the COS group had significantly higher mRNA expression of CPT1A (1.254 ± 0.156 vs 1.908 ± 0.087,F= 31.734,P< 0.01). The COS group had significantly lower protein expression of SREBP-1c and FAS than the model group (0.161 ± 0.081 vs 0.351±0.016,F= 188.920,P< 0.01; 0.332 ± 0.023 vs 1.238 ± 0.051,F= 624.069,P< 0.01), and significantly higher protein expression of CPT1A than the model group (1.014 ± 0.033 vs 0.561 ± 0.046,F= 193.793,P< 0.01). COS reduced the TG content in the liver in rats on high-fat diet. COS can reduce the accumulation of TG in the hepatocyte model of nonalcoholic fatty liver disease and in the liver in rats on high-fat diet, and the possible mechanism may be related to inhibiting the expression of SREBP-1c and downstream FAS, reducing the synthesis of TG, increasing the expression of CPT1A, and accelerating the breakdown of TG.

Role and mechanism of action of fibroblast growth factor-21 in reducing triglyceride in nonalcoholic fatty liver disease

To investigate the role and mechanism of action of fibroblast growth factor-21 (FGF-21) in reducing triglyceride (TG) in the in vitro and in vivo models of nonalcoholic fatty liver disease (NAFLD). (1) A mixture of free fatty acids was used to establish a model of steatosis in L02 cells, and the cells were treated with various concentrations of FGF-21 or fenofibrate. Twenty-four hours later, oil red O staining was performed to observe the degree of steatosis, and intracellular TG content was determined. RT-PCR and Western blot were applied to measure the mRNA and protein expression of sterol regulatory element-binding protein-1c (SREBP-1c). (2) High-fat diet was used to establish a mouse model of steatosis, and these mice were intraperitoneally injected with FGF-21 or fenofibrate. Eight weeks later, whole blood and liver samples were collected, and HE staining was performed to observe steatosis. Meanwhile, the serum levels of TG, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were measured, and TG content in the liver was also measured. One-way analysis of variance was used for comparison of data between multiple groups, and the least significant difference t-test was used for comparison between any two groups. (1) Compared with the control group, the model group showed significant steatosis, with significant increases in intracellular lipid droplets and TG content (t = -20.57, P < 0.01), while FGF-21 reduced the number of intracellular lipid droplets and TG content (F = 98.16, P < 0.01) in a dose-dependent manner. In addition, the model group had significantly increased mRNA and protein expression of SREBP-1c compared with the control group (t = -10.73 and -0.1006, both P < 0.01), while FGF-21 down-regulated the mRNA and protein expression of SREBP-1c (F = 161.35 and 36.72, both P < 0.01). (2) Compared with the mice in the control group, those in the model group showed significant steatosis and had significant increases in serum TG level and TG content in the liver (t = -18.84 and 15.71, both P < 0.01). FGF-21 relieved hepatic steatosis and reduced the serum TG level and TG content in the liver (t = 18.11 and 9.46, both P < 0.01). Moreover, FGF-21 reduced the serum levels of ALT and AST in NAFLD mice (t = 25.93 and 12.50, both P < 0.01). FGF-21 can inhibit the synthesis of TG through suppressing the expression of SREBP-1c, which further confirms the potential therapeutic effect of FGF-21 in the treatment of NAFLD. This may provide new ideas for the treatment of NAFLD.

Expression and clinical significance of LXRα and SREBP-1c in placentas of preeclampsia.

ObjectiveTo evaluate the expression and correlations of liver X receptor alpha (LXRa) and its target gene sterol regulatory element-binding protein-1c (SREBP-1c) in placentas of preeclampsia (PE) and their significance in PE.MethodsPregnancies were divided into two groups, 60 cases (29 cases of mild and 31 cases of severe) of PE group and 56 cases of normal group. The level of mRNA and protein of LXRa and SREBP-1c were analyzed by reverse transcription-polymerase chain reaction (RTPCR) and immunohistochemistry (IHC) in the placentas.ResultsRT-PCR and IHC results showed that the mRNA and protein expression of both LXRa and SREBP-1c increased gradually with the extent of PE among normal pregnancy, mild PE and severe PE groups, and the differences were of statistically significance (P<0.01 or P<0.05). There were positive correlations between the expression of LXRa mRNA and SREBP-1c mRNA, also between LXRa mRNA and LXRa protein (r=0.521, P<0.01; r=0.422, P<0.01). The expression of SREBP-1c mRNA positively correlated with its protein level (r=0.598, P<0.01). There were positive correlations between the expression of LXRa protein and SREBP-1c protein (r=0.612, P<0.01).ConclusionThe expression of LXRa is elevated significantly in placentas of PE patients, and might contribute for promoting the transcription and translation of its target gene SREBP1-c, which is related to the occurrence and development of PE.

Hypoglycemic and Hypolipidemic Effects of Lycium barbarum Polysaccharide in Diabetic Rats

ObjectiveTo study the antidiabetic effects and the underlying molecular mechanisms of Lycium barbarum polysaccharide (LBP) and its DEAE cellulose elution fraction LBP-IV in diabetic rats induced by high fat diet (HFD) and streptozotocin (STZ). MethodsAfter ig administration of LBP-IV [50, 100, and 200 mg/(kg·d)] and LBP [100 mg/(kg·d)] once daily for consecutive 4 weeks to diabetic rats, the glucose and lipids in blood, mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK), sterol regulatory element binding-protein-1c (SREBP-1c), and fatty acid synthase (FAS) in liver were determined. ResultsIg administration of LBP and LBP-IV significantly decreased the levels of blood glucose, HbA1c, TC, TG, and LDL-C, as well as the hepatic mRNA expression of PEPCK, SREBP-1c, and FAS, whereas significantly increased the oral glucose tolerance of diabetic rats. ConclusionThe findings suggest that the antidiabetic effects of LBP and LBP-IV are associated with the decreased hepatic mRNA expression of PEPCK, SREBP-1c, and FAS in HFD-STZ induced diabetic rats.

Effect of neonatal overfeeding on associated enzymes of lipid metabolism in rat liver

Objective To investigate the effect of neonatal overfeeding on the expression of lipid metabolic associated enzymes and molecular mechanisms in the livers of rats. Methods Male Sprague-Dawley rats were randomly assigned to litter sizes of three group (small litters, SL group) or ten (normal litters, NL group) on postnatal day 3.Body weight, milk intake, liver and fat pad (epididymal and retroperitonea) weight, and hepatic histological analysis were recorded in week 2 and week 3, respectively.The levels of lipids were detected by the automatic biochemical analyzer.The mRNA expressions of acetyl-CoA carboxylase (ACC), lipoprotein lipase (LPL), liver-type fatty acid-binding protein (L-FABP), carnitine palmitoyltransferase 1(CPT1), microsomal triglyceride transfer protein (MTP), sterol regulatory element-binding protein-1c (SREBP-1c) and peroxisome proliferator activated receptor α (PPARα)in liver were determined by real time PCR; the protein expressions of SREBP-1c and PPARα were determined by Western lot. Results As early as week 2, the body weight of rats in SL group began to elevate (t=-5.997, P<0.001) and food intake (t=-3.462, P=0.002) compared with the rats in NL group, and persistent to weaning (body weight: t=-17.019, P<0.001; food intake: t=-2.276, P=0.031). By the time of 3 weeks old, SL rats increased visceral fat pad [retroperitonea (t=-7.643, P<0.001), epididymal (t=5.997, P=0.001)], liver weight (t=-7.812, P<0.001), hepatosomatic index (t=-3.829, P=0.003) and serum triglyceride (TG) level (t=-2.703, P=0.022) compared with those of NL rats, as well as the level of hepatic ACC mRNA (t=-3.751, P=0.007), LPL (t=-2.721, P=0.017) and L-FABP mRNA (t=-2.521, P=0.026) .While CPT1 mRNA (t=-1.531, P=0.155) and MTP mRNA (t=-1.741, P=0.098) levels remained unchanged in both groups.Hepatic SREBP-1c mRNA expression increased in SL rats after 2 to 3 weeks (t=-2.836, P=0.016), paralleled with ACC and LPL mRNA expression; while the mRNA and protein expression of PPARα remained unchanged (t=-0.854, P=0.411). Conclusions Postnatal overfeeding can promote higher liver pad and dyslipidemia at the time of weaning.The process may be regulated by up-regulated expression of ACC, LPL and L-FABP.SREBP-1c may be participated in the regulation of ACC, a rate-limiting enzyme involved in lipogenesis. Key words: Nutritional programming; Liver; Lipid metabolism; Rat

Gut Microbial Fatty Acid Metabolites Reduce Triacylglycerol Levels in Hepatocytes.

Hydroxy and oxo fatty acids were recently found to be produced as intermediates during gut microbial fatty acid metabolism. Lactobacillus plantarum produces these fatty acids from unsaturated fatty acids such as linoleic acid. In this study, we investigated the effects of these gut microbial fatty acid metabolites on the lipogenesis in liver cells. We screened their effect on sterol regulatory element binding protein-1c (SREBP-1c) expression in HepG2 cells treated with a synthetic liver X receptor α (LXRα) agonist (T0901317). The results showed that 10-hydroxy-12(Z)-octadecenoic acid (18:1) (HYA), 10-hydroxy-6(Z),12(Z)-octadecadienoic acid (18:2) (γHYA), 10-oxo-12(Z)-18:1 (KetoA), and 10-oxo-6(Z),12(Z)-18:2 (γKetoA) significantly decreased SREBP-1c mRNA expression induced by T0901317. These fatty acids also downregulated the mRNA expression of lipogenic genes by suppressing LXRα activity and inhibiting SREBP-1 maturation. Oral administration of KetoA, which effectively reduced triacylglycerol accumulation and acetyl-CoA carboxylase 2 (ACC2) expression in HepG2 cells, for 2 weeks significantly decreased Srebp-1c, Scd-1, and Acc2 expression in the liver of mice fed a high-sucrose diet. Our findings suggest that the hypolipidemic effect of the fatty acid metabolites produced by L. plantarum can be exploited in the treatment of cardiovascular diseases or dyslipidemia.

Preventive effect of total glycosides from Ligustri Lucidi Fructus against nonalcoholic fatty liver in mice.

The protective effects of the total glycosides from Ligustri Lucidi Fructus against nonalcoholic fatty liver (NAFL) in mice were investigated. Liver injury was induced by the administration of high fat diet for 60 days. During this period, the model group received high fat diet only; the treatment groups received various drugs plus high fat diet. Compared with the model group, the total glycosides significantly decreased the contents of triglyceride (TG) and cholesterol (TC), as well as the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum. Moreover, the contents of TG and TC in liver tissue and the liver index were reduced. Histological findings also confirmed antisteatosis. Compared with the model group, total glycosides significantly reduced the levels of the sterol regulatory element binding protein-1c (SREBP-1c) and liver X receptor-a (LXR-α) protein, and down-regulated the expression of SREBP-1c, LXR-α and interleukin-6 (IL-6) mRNA in the liver. These results suggest that the total glycosides are effective in the treatment of NAFL of mice. Their mode of action is associated with inhibiting SREBP-1c, LXR-α and IL-6 mRNA, reducing lipid synthesis factor SREBP-1c and LXR-α protein and gene expression, suppressing inflammatory responses, then decreasing serum lipid and hepatic lipid.

도라지, 울금의 Aspergillus oryzae 발효에 의한 항비만효과 연구

본 연구는 항비만 소재로 연구된 도라지와 울금 소재를 대상으로 발효 전과 후 3T3-L1 지방세포의 분화 억제효능을 확인하고자 하였다. 그 결과 발효 전 도라지와 울금은 3T3-L1 세포의 분화에 영향을 미치지 못하는 것을 확인할 수 있었다. Apsergillus oryzae 발효를 통해 만들어진 소재들은 도라지 발효물의 플라보노이드 증가를 제외하면 모든 소재에서 폴리페놀과 플라보노이드의 함량 및 항산화 활성이 감소하는 것을 확인할 수 있었다. 그러나 발효 전과 다르게 발효 후 도라지, 울금 및 도라지와 울금 혼합물의 발효물에서 3T3-L1 세포의 분화억제능이 oil red O 염색법을 통해 관찰되었으며, mRNA 발현 확인을 통해 SREBP-1c와 <TEX>$PPAR{\gamma}$</TEX>의 발현을 억제하여 분화를 억제할 수 있음을 확인하였다. 이는 Apsergillus oryzae 발효과정이 도라지와 울금의 항비만효과를 개선할 수 있으며, 발효과정을 통해 새로운 항비만 유효성분이 생성되었음을 예측할 수 있었다. 본 연구결과를 통해 Apsergillus oryzae 발효공정이 도라지와 울금의 기능을 향상시켜 우수한 기능성 제품의 개발에 유용하게 활용될 수 있음을 확인할 수 있었으며, 개발공정의 기초자료를 제공할 것으로 사료된다. In the present study, the phenolic compound level, antioxidant activity, and inhibition of lipid accumulation in Aspergillus oryzae-fermented water extracts of the Platycodon grandiflorum (PG) root and the Curcuma longa (CL) root were determined. Total polyphenol and flavonoid contents were decreased after fermentation. However, the flavonoid content of the fermented PG (FPG) was increased by 2.9-fold that of the PG before fermentation. In addition, the antioxidant activities were significantly decreased following fermentation. The potential anti-obesity activity was assessed by determining lipid accumulation and mRNA expression of sterol regulatory element-binding protein 1c (SREBP-1c) and peroxisome proliferator-activated receptor gamma (<TEX>$PPAR{\gamma}$</TEX>) in 3T3-L1 cells. Aspergillus-fermented extracts of PG and CL roots decreased lipid accumulation, and mRNA expression of SREBP-1c and <TEX>$PPAR{\gamma}$</TEX> in 3T3-L1 cells. These results indicate that Aspergillus fermentation augments the anti-obesity activity of PG and CL by regulating the expression of the genes involved in lipid accumulation and cell differentiation of 3T3-L1 cells.

Iodine Excess Induces Hepatic Steatosis Through Disturbance of Thyroid Hormone Metabolism Involving Oxidative Stress in BaLB/c Mice

Iodine excess is emerging as a new focus. A better understanding of its hazardous effects on the liver will be of great benefit to health. The aim of this study is to illustrate the effects of iodine excess on hepatic lipid homeostasis and explore its possible mechanisms. One hundred twenty BaLB/c mice were given iodine at different levels (0, 0.3, 0.6, 1.2, 2.4, and 4.8 mg I/L) in drinking water for 1 or 3 months. Lipid parameters and serum thyroid hormones were measured. Hepatic type 1 deiodinase activity and oxidative stress parameters were evaluated. The mRNA expression of sterol regulatory element-binding protein-1c (SREBP-1c) and fatty acid synthase (FAS) was detected by real-time polymerase chain reaction. Dose-dependent increase of hepatic triglyceride content was detected (r = 0.680, P < 0.01) in iodine-loaded groups. Evident hepatic steatosis was observed in 2.4 and 4.8 mg I/L iodine-loaded groups. The activities of antioxidant enzymes (glutathione peroxidase and superoxide dismutase) were decreased, and the malondialdehyde level was increased by excessive iodine in both serum and liver in a dose-dependent manner, accompanying the decrease of hepatic D1 activity. That resulted in the increase of serum total thyroxine and the decrease of serum total triiodothyronine in iodine-loaded groups. The mRNA expression of SREBP-1c and FAS was increased in iodine-loaded groups in response to the change of serum triiodothyronine. Present findings demonstrated that iodine excess could dose dependently induce hepatic steatosis. Furthermore, our data suggested that the disturbance of thyroid hormone metabolism involving oxidative stress may play a critical role in iodine excess-induced hepatic steatosis.

Hepatitis C virus core protein stimulates fibrogenesis in hepatic stellate cells involving the obese receptor

Hepatitis C virus core protein (HCVcp), which is secreted by infected cells, is reported as an immunomodulator in immune cells. However, the effects of HCVcp on hepatic stellate cells (HSCs), the key cells in liver fibrosis, still remain unclear. In this study, we investigated the effects of HCVcp on obese receptor (ObR) related downstream signaling pathways and fibrogenic gene expression in HSCs. LX-2, a human HSC line, was incubated with HCVcp. Inhibitors and short interfering RNAs were used to interrogate the mechanisms of HCVcp action on HSCs. HCVcp (20-100 ng/ml) concentration-dependently stimulated α-smooth muscle actin (α-SMA) protein expression and mRNA expression of α-SMA, procollagen α2(I) and TGF-β1 genes, with a plateau of 220% of controls at 100 ng/ml. HCVcp induced mRNA and protein expression of ObR. Blocking of Ob-Rb with a neutralizing antibody inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and AMPKα stimulated by HCVcp. Furthermore, knockdown of Ob-Rb down-regulated HCVcp-induced STAT3, AKT, and AMPKα phosphorylation, and reversed HCVcp-suppressed mRNA expression of matrix metalloproteinase (MMP)-1, peroxisome proliferator-activated receptor (PPAR)γ and sterol regulatory element binding protein-1c (SREBP-1c) genes. AMPKα signaling blockade reversed HCVcp-suppressed SREBP-1c mRNA expression. HCVcp stimulated reactive oxygen species formation and gp91(phox) (a component of NADPH oxidase) protein expression, together with AKT phosphorylation, leading to suppression of PPARγ and SREBP-1c genes. Our results provide a new finding that HCVcp induced ObR-dependent Janus Kinase (JAK) 2-STAT3, AMPKα, and AKT signaling pathways and modulated downstream fibrogenetic gene expression in HSCs.

Differential expression of lipid metabolism genes in the liver and adipose tissue of mice treated with evodiamine

Evodiamine is the main active alkali of Wu Zhuyu, a widely distributed Chinese herb. It plays an important role in the regulation of body fat deposition. In this study, we aimed to investigate the effect of evodiamine administration on the expression of genes involved in lipid metabolism in the liver and adipose tissue. Fasted mice were subcutaneously injected with evodiamine (37 °C, 20 mg/kg), and the core body temperature change and expression levels of lipid metabolism-related genes were evaluated at baseline, 0.5, 1, and 2 h. We detected the mRNA expression of fatty acid synthesis enzyme (FAS), peroxisome proliferator-activated receptor gamma (PPAR-γ), sterol regulatory element binding protein 1c (SREBP-1c), triglyceride hydrolase (TGH), and hormone-sensitive lipase (HSL) by real-time PCR and analyzed their correlation with core body temperature. Our results showed that the core body temperature was reduced greater than 1 °C with evodiamine treatment at 1 and 2 h (P < 0.01). In mouse livers, SREBP-1c, HSL, and TGH mRNA expression was significantly increased, and they reached the highest levels 1 h after injection (P < 0.01). However, PPAR-γ mRNA expression was decreased and reached a significant level at 0.5 h (P < 0.01) and FAS mRNA expression was not significantly different; FAS and SREBP-1c mRNA expression were reduced and reached significant levels at 1 h (P < 0.01). Of note, other genes demonstrated opposite changes in adipose tissue, and HSL mRNA expression was significantly reduced at 0.5 h (P < 0.01). The decreasing core temperature had a significant negative correlation with the expression of TGH, HSL, FAS, and SREBP- 1c mRNA in the liver (P < 0.01), but had significant positive correlation with levels of FAS and SREBP-1c mRNA in adipose tissue (P < 0.01). In light of these results, the main mechanism of the regulation of body fat deposition by evodiamine is raising energy consumption through reducing body temperature and promoting fat decomposition.