Sterol Regulatory Element-binding Protein-1c mRNA 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.

Myricetin Ameliorates Ethanol-Induced Lipid Accumulation in Liver Cells by Reducing Fatty Acid Biosynthesis.

Alcoholic liver disease is a serious threat to human health. The development of drug candidates from complementary and alternative medicines is an attractive approach. Myricetin can be found in fruit, vegetables, and herbs. This study investigates the protective effect of myricetin on ethanol-induced injury in mouse liver cells. Oil-red O staining, assays of oxidative stress and measurements of inflammatory markers in mouse AML12 liver cells collectively demonstrate that myricetin elicits a curative effect on ethanol-induced injury. Next, the role of myricetin in the metabolic regulation of ethanol pathology in liver cells is assessed by gas chromatography coupled with mass spectrometry. Myricetin inhibits ethanol-stimulated fatty acid biosynthesis. Additionally, dodecanoic acid may be proposed as a potential biomarker related to ethanol pathology or myricetin therapy. It is also observed that myricetin enhances ethanol-induced inhibition of the mitochondrial electron transport chain. Moreover, fumaric acid is found to be a candidate biomarker related to ethanol toxicity or myricetin therapy. Quantitative reverse-transcription-PCR shows that ethanol-induced fatty acid synthase and sterol regulatory element-binding protein-1c mRNA levels are alleviated by myricetin. Finally, myricetin increases ethanol-induced inhibition of phosphorylation of AMP-activated protein kinase. These results elucidate the pharmacological mechanism of myricetin on ethanol-induced lipid accumulation.

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.

Leptin up-regulates microRNA-27a/b-3p level in hepatic stellate cells

Obese patients, often accompanied by hyperleptinemia, are prone to liver fibrogenesis. Leptin is an adipocyte-derived hormone and plays a promotion role in liver fibrosis. Sterol regulatory element binding protein-1c (SREBP1c) exerts a crucial role in inhibiting hepatic stellate cell (HSC) activation, a key step in liver fibrogenesis. Our previous studies indicated that leptin inhibited SREBP1c expression, contributing to leptin-induced HSC activation and liver fibrosis. microRNAs (miR) have emerged as important layers of regulatory control and regulate gene expression, and are implicated in numerous diseases. The present study revealed leptin up-regulation of miR-27a/b-3p levels in HSCs in vitro and in vivo. Three signaling pathways were required for leptin regulation of miR-27a/b-3p levels. miR-27a/b-3p could reduce SREBP1c and liver x receptor α (LXRα) levels, increased α-smooth muscle actin (α-SMA, a marker for HSC activation) and α1(I)collagen levels in cultured HSCs. miR-27a/b-3p regulation of SREBP1c and LXRα were independent of 3′-untranslated region of SREBP1c and LXRα mRNA. In vivo experiments further demonstrated the miR-27a/b-3p involved in leptin-associated decrease in SREBP1 level in HSCs, HSC activation, and liver fibrosis. These data might have potential implications for our understanding of molecular mechanisms underlying leptin roles in liver fibrogenesis of obese patients with hyperleptinaemia.

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.

Diosgenin prevents high-fat diet-induced rat non-alcoholic fatty liver disease through the AMPK and LXR signaling pathways.

Non-alcoholic fatty liver disease(NAFLD) is a major public health concern worldwide. The aim of the present study was to observe the effect of diosgenin on NAFLD and investigate the underlying mechanisms. Diosgenin treatment increased the phosphorylation of AMP-activated protein kinase(AMPK) and acetyl-CoA carboxylase(ACC) in HepG2 cells. Diosgenin significantly inhibited high glucose(HG)-induced triglyceride (TG) accumulation and sterol regulatory element‑binding protein-1c(SREBP-1c) mRNA increase in HepG2 cells, which were partially abolished by the AMPK inhibitor compoundC. Diosgenin also significantly inhibited the increase of liver Xreceptor(LXR)α mRNA induced by HG or T0901317. However, T0901317‑induced upregulation of LXRα and SREBP-1c mRNA was not blocked by compoundC. Following a high-fat diet for 16weeks, the body and liver weights of the experimental rats were significantly increased, but this effect was significantly suppressed by diosgenin. Diosgenin and fenofibrate ameliorated lipid deposition in the liver and reduced the increase of hepatic TG content. Diosgenin significantly decreased the alanine aminotransferase(ALT) level, whereas fenofibrate significantly increased the ALT and aspartate aminotransferase levels. Diosgenin also increased AMPK and ACC phosphorylation and suppressed LXRα in the liver. Inconclusion, the results of the present study suggested that diosgenin is a potential agent for preventing the development of NAFLD through the AMPK and LXR signaling pathways.

Arsenic trioxide suppresses liver X receptor β and enhances cholesteryl ester transfer protein expression without affecting the liver X receptor α in HepG2 cells

Chronic arsenic exposure is associated with cerebrovascular disease and the formation of atherosclerotic lesions. Our previous study demonstrated that arsenic trioxide (ATO) exposure was associated with atherosclerotic lesion formation through alterations in lipid metabolism in the reverse cholesterol transport process. In mouse livers, the expression of the liver X receptor β (LXR-β) and the cholesteryl ester transfer protein (CETP) was suppressed without any changes to the lipid profile. The aim of this study was to elucidate whether ATO contributes to atherosclerotic lesions by suppressing LXR-β and CETP levels in hepatocytes. HepG2 cells, human hepatocytes, were exposed to different ATO concentrations in vitro. Cell viability was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. The liver X receptor α (LXR-α), LXR-β, sterol regulatory element-binding protein-1c (SREBP-1c) and CETP protein levels were measured by Western blotting, and their mRNA levels were measured by real-time PCR. Cholesterol efflux was analyzed by flow cytometry.The results showed ATO inhibited LXR-β mRNA and protein levels with a subsequent decrease in SREBP-1c protein levels and reduced cholesterol efflux from HepG2 cells into the extracellular space without influencing LXR-α mRNA and protein levels. CETP protein levels of HepG2 cells were significantly elevated under arsenic exposure. Transfection of LXR-β shRNA did not change CETP protein levels, implying that there is no cross-talk between LXR-β and CETP. In conclusion, arsenic not only inhibits LXR-β and SREBP-1c mRNA and protein levels but also independently increases CETP protein levels in HepG2 cells.

Insulin induction of SREBP-1c in rodent liver requires LXRα-C/EBPβ complex

Insulin increases lipid synthesis in liver by activating transcription of the gene encoding sterol regulatory element-binding protein-1c (SREBP-1c). SREBP-1c activates the transcription of all genes necessary for fatty acid synthesis. Insulin induction of SREBP-1c requires LXRα, a nuclear receptor. Transcription of SREBP-1c also requires transcription factor C/EBPβ, but a connection between LXRα and C/EBPβ has not been made. Here we show that LXRα and C/EBPβ form a complex that can be immunoprecipitated from rat liver nuclei. Chromatin immunoprecipitation assays showed that the LXRα-C/EBPβ complex binds to the SREBP-1c promoter in a region that contains two binding sites for LXRα and is known to be required for insulin induction. Knockdown of C/EBPβ in fresh rat hepatocytes or mouse livers in vivo reduces the ability of insulin to increase SREBP-1c mRNA. The LXRα-C/EBPβ complex is bound to the SREBP-1c promoter in the absence or presence of insulin, indicating that insulin acts not by increasing the formation of this complex, but rather by activating it.

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.

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.

Beer Is Less Harmful for the Liver than Plain Ethanol: Studies in Male Mice Using a Binge-Drinking Model.

Mechanisms involved in the less damaging effects of beer in comparison to hard spirits have not yet been fully understood. The aim of the study was to determine if the effect of beer intake on the liver differs from that of plain ethanol and if so to determine mechanisms involved. Male C57BL/6J mice received either ethanol, beer (ethanol content: 6 g/kg body weight) or iso-caloric maltodextrin solution. Markers of steatosis, lipogenesis, activation of the toll-like receptor-4 signaling cascade and lipid export in liver and tight junction proteins in duodenum were measured 6 and 12 h after acute ethanol or beer intake. Alcohol ingestion resulted in a significant increase of hepatic triglyceride accumulation 6 and 12 h after ingestion, respectively, being markedly lower in mice fed beer. Expression of sterol regulatory element-binding protein-1c mRNA was significantly lower 12 h after alcohol or beer exposure, while fatty acid synthase mRNA expression was induced in livers of ethanol-fed mice and to a lesser extent in mice fed beer 6 h after acute alcohol ingestion. Protein levels of tight junction proteins in the small intestine were similar between groups while expression of myeloid differentiation primary response gene 88 in livers was significantly induced in ethanol- but not in beer-fed mice. Concentrations of 4-hydroxynonenal protein adducts and inducible nitric oxide synthase protein were also only induced in livers of mice fed ethanol. Protein levels of apolipoprotein B were induced in livers of beer-fed mice only. Our data suggest that beer is less harmful on the development of acute alcohol-induced liver damage than plain ethanol in male mice.

발효울금 주정추출물부터 분리된 에틸아세테이트 분획물에 대한 3T3-L1 세포에서의 지방 형성 억제 효과

FCEE를 3T3-L1 전지방세포의 분화과정 중에 처리한 후, FCEE가 지방의 축적에 미치는 영향을 확인하였다. FCEE(200 μg/mL)를 세포에 처리한 후 Oil Red O 염색법과 AdipoRed 형광염색법을 이용한 지방 축적과 세포내 중성지방 함량을 측정한 결과, 무처리한 지방세포와 비교하여 각각 10.2%, 13.7% 유의하게 감소하는 것을 확인하였다. 이러한 결과에 대한 기작을 확인하고자 포도당 유입량과 유리 글리세롤 방출량을 측정하였다. FCEE(200 μg/mL) 처리 시 지방세포와 비교하여 포도당 유입량이 36.6% 유의적으로 감소하였으며, 유리 글리세롤 방출량도 8일째에 유의적으로 감소하였다. 이는 지방세포의 분화과정 중에 FCEE의 처리로 분화가 억제되어 지방구의 형성이 억제되고 배양액으로 배출되는 유리 글리세롤의 총량이 감소한 것으로 판단된다. 이러한 결과가 지방세포 분화의 억제에 의한 것인지 판단하기 위해 지방 형성 관련인자의 mRNA 발현량을 측정하였다. FCEE(200 μg/mL)의 처리로 AMPK mRNA 발현량은 지방세포와 비교하여 3배 증가하였으며, SREBP-1c, C/EBPα와 PPARγ mRNA 발현량은 각각 0.6, 0.6 및 0.8배 감소하는 것을 확인하였다. 이상의 결과들로부터 FCEE는 지방 합성을 억제하는 활성을 보유하고 있는 바, 향후 항비만 기능성 식품소재로 활용될 수 있을 것으로 사료된다.

Postnatal overfeeding promotes early onset and exaggeration of high-fat diet-induced nonalcoholic fatty liver disease through disordered hepatic lipid metabolism in rats

Exposure to overnutrition in critical or sensitive developmental periods may increase the risk of developing obesity and metabolic syndrome in adults. Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome, but the relationship among postnatal nutrition, lipid metabolism, and NAFLD progression during development remains poorly understood. Here we investigated in a rat model whether postnatal overfeeding increases susceptibility to NAFLD in response to a high-fat diet. Litters from Sprague-Dawley dams were culled to three (small litters) or ten (normal litters) pups and then weaned onto a standard or high-fat diet at postnatal day 21 to generate normal-litter, small-litter, normal-litter/high-fat, and small-litter/high-fat groups. At age 16weeks, the small-litter and both high-fat groups showed obesity, dyslipidemia, and insulin resistance. Hepatic disorders appeared earlier in the small-litter/high-fat rats with greater liver mass gain and higher hepatic triglycerides and steatosis score versus normal-litter/high-fat rats. Hepatic acetyl-CoA carboxylase activity and mRNA expression were increased in small-litter rats and aggravated in small-litter/high-fat rats but not in normal-litter/high-fat rats. The high expression in small-litter/high-fat rats coincided with high sterol regulatory element-binding protein-1c mRNA and protein expression. However, mRNA expression of enzymes involved in hepatic fatty acid oxidation (carnitine palmitoyltransferase 1) and output (microsomal triglyceride transfer protein) was decreased under a high-fat diet regardless of litter size. In conclusion, overfeeding related to small-litter rearing during lactation contributes to the NAFLD phenotype when combined with a high-fat diet, possibly through up-regulated hepatic lipogenesis.

The influence of dietary taurine and reduced housing density on hepatic functions in laying hens

To investigate the influence of dietary taurine and reduced housing density on hepatic functions in laying hens, green-shell laying hens were randomly assigned to 3 groups: a free-range group, a caged group with low-density, and a caged group with high-density. Each group was further divided into the control (C) and taurine-treatment (T) groups. All the test birds were fed the same basic diet, except that the T groups were supplemented with 0.1% taurine. After 15 d, sera and liver were aseptically collected. The results show that dietary taurine supplementation and reduced housing density significantly attenuated physiopathological changes in the liver. When compared with the free-range group, serum alanine aminotransterase and aspartate aminotransterase in the caged hens were significantly higher and were deceased by taurine (P < 0.05). Serum inducible nitric oxide synthase activity in caged hens was higher than that in free-range hens, and taurine reduced serum inducible nitric oxide synthase activities in the low-density group (P < 0.05). Nuclear factor-κB DNA-binding activity increased significantly in the high-density housing group when compared with the other 2 housing patterns and was decreased by taurine (P < 0.05). Taurine reduced the expression of tumor necrosis factor-α mRNA in all 3 rearing patterns, IL-4 mRNA expression in the high-density group, and IL-10 in the low-density group (P < 0.05). Malondialdehyde levels decreased in serum and liver from T groups and serum total antioxidation capability levels increased significantly (P < 0.05) in the low-density group. Dietary taurine supplementation decreased acetyl-CoA and sterol regulatory element-binding protein-1c mRNA expression in the high-density groups (P < 0.05). Taurine significantly increased lipoprotein lipase mRNA expression in the high-density group and peroxisome proliferator receptor mRNA expression both in the low- and high-density groups (P < 0.05). Taurine supplementation reduced total cholesterol levels in the low- and high-density groups, decreased triglyceride and low-density lipoprotein cholesterol levels in high-density groups, and increased high-density lipoprotein cholesterol levels in all 3 rearing patterns (P < 0.05). Our data demonstrate that dietary taurine and reduced housing density offer significant protection from hepatic damage in laying hens.

The Effect and Mechanism of Tamoxifen-Induced Hepatocyte Steatosis in Vitro

The aim of this study was to determine the effect and mechanism of tamoxifen (TAM)-induced steatosis in vitro. HepG 2 (Human hepatocellular liver carcinoma cell line) cells were treated with different concentrations of TAM for 72 h. Steatosis of hepatocytes was determined after Oil Red O staining and measurement of triglyceride (TG) concentration. The expressions of genes in the TG homeostasis pathway, including sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase (SCD), carnitine palmitoyltransferase 1 (CPT1) and microsomal triglyceride transfer protein (MTP), were examined using quantitative real-time PCR and Western blot analysis. Cell proliferation was examined using the cell counting kit-8 (CCK-8) assay. We found that hepatocytes treated with TAM had: (1) induced hepatocyte steatosis and increased hepatocyte TG; (2) upregulation of SREBP-1c, FAS, ACC, SCD and MTP mRNA expressions (300%, 600%, 70%, 130% and 160%, respectively); (3) corresponding upregulation of protein expression; and (4) no difference in HepG 2 cell proliferation. Our results suggest that TAM can induce hepatocyte steatosis in vitro and that the enhancement of fatty acid synthesis through the upregulations of SREBP-1c and its downstream target genes (FAS, ACC and SCD) may be the key mechanism of TAM-induced hepatocyte 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.