Cholesterol Metabolism-related Genes Research Articles

Expression profiles of cholesterol metabolism-related genes are altered during development of experimental autoimmune encephalomyelitis in the rat spinal cord

Increased evidence suggests that dysregulation of cholesterol metabolism may be a key event contributing to progression of multiple sclerosis (MS). Using an experimental autoimmune encephalomyelitis (EAE) model of MS we revealed specific changes in the mRNA and protein expression of key molecules involved in the maintaining of cholesterol homeostasis in the rat spinal cord: 3-hydroxy-3-methylglutaryl-coenzyme-A reductase (HMGCR), apolipoprotein E (ApoE) and cholesterol 24-hydroxylase (CYP46A1) during the course of disease. The presence of myelin lipid debris was seen only at the peak of EAE in demyelination loci being efficiently removed during the recovery period. Since CYP46A1 is responsible for removal of cholesterol excess, we performed a detailed profiling of CYP46A1 expression and revealed regional and temporal specificities in its distribution. Double immunofluorescence staining demonstrated CYP46A1 localization with neurons, infiltrated macrophages, microglia and astrocytes in the areas of demyelination, suggesting that these cells play a role in cholesterol turnover in EAE. We propose that alterations in the regulation of cholesterol metabolism at the onset and peak of EAE may add to the progression of disease, while during the recovery period may have beneficial effects contributing to the regeneration of myelin sheath and restoration of neuronal function.

Cholesterol-lowering effect of astringent persimmon fruits (Diospyros kaki Thunb.) extracts.

This study aimed to investigate the effects of ethanol extract of astringent persimmon on antioxidant activity, cholesterol, 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase activity, and mRNA expression of cholesterol metabolism-related genes in human hepatoma cell line (HepG2 cells). In the results, DPPH and ABTS radical scavenging activity showed that the different types cultivars of astringent persimmon was similar to Vitamin C as positive control. However, there are not significant differences among samples. In addition, our results showed that cholesterol amounts and HMG-CoA reductase activity were inhibited by astringent persimmon in HepG2 cells. Further, treatment with astringent persimmon upregulated the expression of LDL receptor and SREBP-2, and also increased the level of HDL-associated ABCA1. Taken together, our results indicate that astringent persimmon regulate cholesterol accumulation by inhibiting the oxidative stress and controlling the levels of LDL & HDLassociated gene.

Effects and Interactions of Prenatal Ethanol Exposure, a Post-Weaning High-Fat Diet and Gender on Adult Hypercholesterolemia Occurrence in Offspring Rats

Background/Aims: Prenatal ethanol exposure (PEE) could induce intrauterine programming of hypothalamic-pituitary-adrenal axis-associated neuroendocrine metabolism, resulting in intrauterine growth retardation and susceptibility to adult hypercholesterolemia in offspring. This study aimed to analyse the effects and interactions of PEE, a post-weaning high-fat diet (HFD) and gender on the occurrence of adult hypercholesterolemia in offspring rats. Methods: Wistar female rats were treated with ethanol (4 g/kg.d) at gestational days 11-20. The offspring were given a normal diet or HFD after weaning, and the blood cholesterol metabolism phenotype and expression of hepatic cholesterol metabolism related genes were detected in 24-week-old offspring. Furthermore, the interactions among PEE, HFD, and gender on hypercholesterolemia occurrence were analysed. Results: PEE increased the serum total cholesterol (TCH) and low-density lipoprotein-cholesterol (LDL-C) levels and decreased the serum high-density lipoprotein-cholesterol (HDL-C) level in adult offspring rats; the changes in female offspring were greater than those in males. At the same time, the mRNA expression levels of hepatic cholesterol metabolic enzymes (apolipoprotein B (ApoB) and 7α-hydroxylase (CYP7A1))—were increased, while the mRNA expression levels of the scavenger receptor B1 (SR-B1) and LDL receptor (LDLR) were decreased. Furthermore, a three-way ANOVA showed there were interactions among PEE, post-weaning HFD and gender. For PEE offspring, a post-weaning HFD aggravated the elevated hepatic ApoB and CYP7A1 expression and reduced SR-B1 and LDLR expression; the changes in hepatic SR-B1 and CYP7A1 expression were greater in female HFD rats than in males. Conclusion: Our findings suggest that a post-weaning HFD could aggravate offspring hypercholesterolemia caused by PEE and that this mechanism might be associated with hepatic cholesterol metabolic disorders that are aggravated by a post-weaning HFD; hepatic cholesterol metabolism was more sensitive to neuroendocrine metabolic alterations by PEE and a post-weaning HFD in the female offspring than in the male offspring.

Functional Probiotic Characterization and In Vivo Cholesterol-Lowering Activity of Lactobacillus helveticus Isolated from Fermented Cow Milk.

We characterized the probiotic properties of Lactobacillus helveticus strains KII13 and KHI1 isolated from fermented cow milk by in vitro and in vivo studies. The strains exhibited tolerance to simulated orogastrointestinal condition, adherence to Caco-2 cells, and antimicrobial activity. Both L. helveticus strains produced bioactive tripeptides, isoleucylprolyl-proline and valyl-prolyl-proline, during fermentation of milk. KII13 showed higher in vitro cholesterol-lowering activity (47%) compared with KHI1 (28%) and L. helveticus ATCC 15009 (22%), and hence, it was selected for in vivo study of cholesterol-lowering activity in atherogenic diet-fed hypercholesterolemic mice. For the study, mice were divided into four groups (viz., normal diet control group, atherogenic diet control group (HCD), KII13- atherogenic diet group (HCD-KII13), and Lactobacillus acidophilus ATCC 43121-atherogenic diet group (HCD-L.ac) as positive control). The serum total cholesterol level was significantly decreased by 8.6% and 7.78% in the HCD-KII13 and HCD-L.ac groups (p < 0.05), respectively, compared with the HCD group. Low-density lipoprotein cholesterol levels in both HCD-KII13 and HCD-L.ac groups were decreased by 13% and 11%, respectively, compared with the HCD group (both, p < 0.05). Analysis of cholesterol metabolism-related gene expression in mice liver showed increased expression of LDLR and SREBF2 genes in mice fed with KII13. By comparing all the results, we conclude that L. helveticus KII13 could be used as a potential probiotic strain to produce antihypertensive peptides and reduce serum cholesterol.

Growth performance, tissue composition, and gene expression responses in Atlantic salmon (Salmo salar) fed varying levels of different lipid sources

We investigated the influence of dietary fatty acid (FA) composition on growth performance, muscle tissue FA composition, and lipid-related hepatic gene expression in Atlantic salmon. Currently the commercial feed industry primarily uses terrestrial-based fats and oils as the main lipid component in the diet, with minimal provision of fish oil (FO). Therefore, we compared the growth and tissue FA response of salmon smolts (mean initial weight 256gfish−1) after 16weeks on three different terrestrial-based diets, with inclusion at three increasing levels of substitution with FO. The lipid sources used in this study were: FO, camelina oil (CO), canola oil (CA), and camelina oil with poultry fat (CO+PF). The terrestrial-based lipid sources had different FA signatures, on account of varied proportions of the C18 FA: 18:2n−6, 18:3n−3, or 18:1n−9. Inclusion of terrestrial FA and removal of marine FA (20:5n−3, 22:6n−3) were reflected in the FA composition of the muscle, and affected growth performance (based on lipid source and inclusion level) and hepatic gene expression of several lipid metabolism-relevant genes. Multiple regression analysis revealed that dietary lipid source affected growth performance, even when inclusion level (as a replacement of FO) was not a factor; suggesting that either inclusion or removal of certain FA in particular lipid sources, even at minimal levels, influenced growth performance. A breakpoint analysis of final weight indicated that dietary levels of <1% each of 20:5n−3 and 22:6n−3 resulted in lower final weight. A multidimensional scaling plot showed that the muscle tissue FA composition of salmon fed diets with CO were distinguishable from salmon fed CA and PF, mainly on account of 18:3n−3, while salmon fed FO were distinct from the terrestrial-based treatments. Salmon fed CO diets maintained 22:6n−3 levels in muscle tissue, and increased in n−3 and n−6 intermediary biosynthesis products in the muscle suggesting endogenous production of 22:6n−3 via dietary 18:3n−3. In addition, significant correlations were observed among dietary and/or muscle tissue FA with elovl2, fadsd5, and srebp1 transcript expression, further supporting FA biosynthesis. Significant relationships were also observed among lipid and cholesterol metabolism-related genes with dietary and tissue sterol and 20:4n−6 content, and they were most often related to cholesterol catabolism (or reduction in synthesis), such as hmgcr, dhcr7, and pparβ1. Correlations among gene expression with dietary and tissue lipid classes and FA content provided evidence to support the link between dietary FA input and phenotypic response.

Antihyperlipidaemic effects of oxyresveratrol-containing Ramulus mori ethanol extract in rats fed a high-cholesterol diet

The antihyperlipidaemic effect of an ethanol extract of Ramulus mori containing a high concentration of oxyresveratrol (ERMO) was investigated in a high-cholesterol diet (HCD)-fed rat model. Cholesterol metabolism-related genes and proteins, such as lecithin cholesterol acyltransferase (LCAT), low-density lipoprotein receptor (LDLR), cholesterol 7α-hydroxylase (CYP7A1), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and acyl coenzyme A cholesterol acyltransferase-2 (ACAT2) were analysed by quantitative real-time reverse-transcription polymerase chain reaction and western blot analysis. ERMO-treated HCD-fed rats had decreased body and liver weights and reduced serum lipid levels, atherogenic index (AI) and coronary artery risk index (CRI). ERMO treatment lowered serum cholesterol levels by increasing the expression of LCAT, CYP7A1 and LDLR and by decreasing HMGCR and ACAT2. Histological analysis of liver and aortic tissues revealed a significant decrease in lipid droplets and foam cell formation in HCD-induced hyperlipidaemic rats treated with ERMO. ERMO is therefore a potentially potent functional food for preventing hyperlipidaemia.

Acute effects of oral olanzapine treatment on the expression of fatty acid and cholesterol metabolism-related gene in rats.

Second-generation antipsychotic drugs (SGAs) have a high risk for serious metabolic side-effects including dyslipidemia. This study aimed to investigate the acute effects of oral olanzapine treatment on the expression of genes for fatty acid and cholesterol biosynthesis in rats. Female Sprague-Dawley rats were treated orally with olanzapine (1mg/kg, equivalent to a human clinical dose of 10mg) via self-administration aimed to measure pharmacokinetics. Based on the pharmacokinetic analysis, the acute effects of olanzapine on sterol regulatory element binding protein (SREBP)-related fatty acid/cholesterol metabolism genes were investigated in the liver and perirenal white adipose tissue (WAT) by Real-time quantitative PCR. A pharmacokinetic analysis demonstrated that the maximum concentration of olanzapine in plasma (Cmax) occurred at 6h with a peak concentration of 276.5ng/ml after a single oral treatment and with a plasma elimination half-life of 3.5h after peak. The mRNA expression of SREBP-2 and target genes for cholesterol synthesis and transport was increased 1.9 8.8 fold compared with the control at 6h after olanzapine administration but returned to basal level at 12h post-treatment, while the increased mRNA expression of SREBP-1c and its targeted fatty acid-related genes appeared at both 6h and 12h post-treatment. The present study provided evidence that olanzapine at a clinically-relevant dose caused abnormal expression of genes involved in lipid metabolism in the liver and WAT. These results suggest that olanzapine may cause dyslipidemia side-effects through direct effects on lipid biosynthesis and efflux genes associated with SREBP-stimulated transcriptional changes.

Implications from a pharmacogenomic analysis: Nerium oleander leaf distillate supplemented diet regulates cholesterol metabolism in rats

Context: Despite the usage of Nerium oleander L. (Apocynaceae) for anticancer studies and traditional remediation, the regulatory effect of N. oleander leaf distillate on cholesterol metabolism is not disclosed sufficiently.Objective: Cholesterol is an important biological molecule and the synthesis rate is regulated by the amount of cholesterol uptake from the diet. The aim of this study was to investigate the regulation of cholesterol metabolism in response to a high-fat diet (HFD) and the effects of N. oleander leaf distillate-supplemented diet (NOHFD) in rats.Materials and methods: Microarray technology was used to clarify the regulation of cholesterol mechanism in HFD and NOHFD-fed rats (375 μg/0.5 mL distilled water applied by gavage). The treatment period was 90 days. Rat liver tissues were used for microarray analysis using the Affymetrix GeneChip Rat Genome platform. Results of groups were statistically analyzed with the Partek 6.6 bioinformatic program.Results: The HFD group exhibited alterations in the expression levels of about 1945 genes with respect to the normal diet (ND) group. The results showed that expression levels of 47 genes were altered related to cholesterol metabolism in HFD and NOHFD groups. The expression levels of seven genes in the NOHFD group were significantly closer to those in the ND group than those of the HFD group.Discussion and conclusion: To conclude, findings suggest that N. oleander leaf distillate-supplemented food has considerable beneficial effects on cholesterol metabolism-related gene expression levels.

Cooked Rice Inhibits Hepatic Fat Accumulation by Regulating Lipid Metabolism–Related Gene Expression in Mice Fed a High-Fat Diet

Although rice has been shown to have beneficial health effects, little is known about the effect of rice on hepatic lipid accumulation as a carbohydrate source. This study investigated the effects and mechanism of action of cooked rice on high-fat diet (HF)-induced fat accumulation. The C57BL/6 mice were divided into three groups and fed a normal diet (NOR), HF, or HF with cooked rice (HF-CR) for 12 weeks. The HF-CR-fed mice had significantly lower body weight gains and abdominal fat mass compared with the HF-fed mice. Consuming cooked rice resulted in significantly lower serum total cholesterol, low-density lipoprotein cholesterol, hepatic lipid content, and lipid droplet number and size. Cooked rice consumption also suppressed the HF-induced increase in expression of lipogenic genes, such as sterol regulatory element-binding protein 1c (SREBP-1c), fatty acid synthase (FAS), stearoyl CoA desaturase 1 (SCD-1), peroxisome proliferator-activated receptor gamma (PPARγ), and CD36. The expression of cholesterol metabolism-related genes, such as acyl-CoA:cholesterol acyltransferase 1 (ACAT1), were also downregulated in the HF-CR-fed mice. Cooked rice may prevent HF-induced fat accumulation by regulating lipid metabolism-related gene expression, and it may be a useful carbohydrate source for preventing nonalcoholic fatty liver disease.

Feeding probiotic Lactobacillus paracasei to Ossabaw pigs on a high-fat diet prevents cholesteryl-ester accumulation and LPS modulation of the Liver X receptor and inflammatory axis in alveolar macrophages

Liver X receptors (LXR) play an integral role in cholesterol metabolism and the inflammatory response. High-fat (HF) diets and microbial infection can antagonize the LXR pathway leading to accumulation of cholesteryl-esters (CE) and increased expression of pro-inflammatory mediators in macrophages. The probiotic bacteria Lactobacillus paracasei possesses cholesterol lowering and immune modulating properties. Therefore, the present study sought to model whether daily feeding of L. paracasei to juvenile Ossabaw pigs fed a HF diet could modulate cholesterol metabolism and the LXR/inflammatory axis in lipopolysacharide (LPS)-stimulated alveolar macrophages (AM). The results showed that AM from pigs fed a HF diet had significantly higher concentrations of CE compared to AM from pigs fed a control (C) diet, but not in pigs fed a HF diet with L. paracasei (HFPB). Ex vivo LPS stimulation of AM opposed LXR agonist-mediated transcription of cholesterol metabolism related genes: ABCA1, CH25H and PPARγ in pigs on the C diet, and LXRα, ABCA1, ABCG1, CH25H and PPARγ in pigs on the HF diet. This effect was abrogated for all these genes except LXRα in AM from pigs given L. paracasei. Protein analysis of culture supernatants revealed that AM from HFPB-fed pigs had significantly lower LPS-induced protein expression of IL-1β than AM from HF-fed pigs. Moreover, AM from pigs fed the C diet and given L. paracasei, had significantly higher mRNA levels of IL-8, and IL-6, in response to LPS. These data demonstrated a role for L. paracasei in modulating AM cholesterol metabolism and the response to LPS.

Rice protein exerts a hypocholesterolemic effect through regulating cholesterol metabolism-related gene expression and enzyme activity in adult rats fed a cholesterol-enriched diet

The major aim of this study is to elucidate the hypocholesterolemic mechanism exerted by rice protein (RP) in adult rats under cholesterol-enriched dietary condition. Compared with casein, the cholesterol levels in plasma and the liver were significantly reduced by RP, accompanying significant inhibition of cholesterol absorption. RP increased the activity and mRNA level of cholesterol 7α-hydroxylase, whereas acyl-CoA:cholesterol acyltransferase activity and gene expression were significantly depressed with consumption of RP. Neither the activity nor gene expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase of RP differed from that of casein. The gene expression of the peroxisome proliferator-activated receptor α and liver X receptor α were significantly activated by consumption of RP. RP did not modify the mRNA level of sterol regulatory element-binding protein-2 with respect to casein. These results suggest RP can induce a cholesterol-lowering effect through modifying cholesterol metabolism-related gene expression and enzyme activity in adult rats.

Effects of short-term refeeding on the expression of genes involved in lipid metabolism in chicks (Gallus gallus)

The aim of this study was to analyze the expression patterns of key genes involved in lipid metabolism in response to feeding in chicks. A total of 18 thirteen day-old male chicks were fasted for 12h. The mRNA levels of the genes in the liver and white adipose tissue were analyzed after 0, 2, and 4h of refeeding. The mRNA levels of sterol regulatory element-binding protein (SREBP) 1, liver X receptor α, peroxisome proliferator-activated receptor (PPAR) γ, acetyl-CoA carboxylase α and fatty acid synthase were significantly increased after 2h of refeeding. In contrast, the mRNA levels of PPARα and carnitine palmitoyltransferase 1a were significantly decreased after 2h of refeeding. The mRNA level of acyl-CoA oxidase was significantly decreased after 4h of refeeding. The mRNA levels of cholesterol metabolism-related genes such as SREBP2 and 3-hydroxy-3-methylglutaryl-CoA reductase were significantly increased after 2h of refeeding. In the white adipose tissue, the mRNA level of PPARγ was significantly increased after 2h of refeeding, whereas the mRNA level of adipose triglyceride lipase was significantly decreased after 4h of refeeding. These results demonstrated that expression of lipid metabolism-related genes is regulated by short-term refeeding in chicks.

Cholesterol-Lowering Activity of Soy-Derived Glyceollins in the Golden Syrian Hamster Model

Hypercholesterolemia is one of the major factors contributing to the risk of cardiovascular disease (CVD), which is the leading cause of death in developed countries. Consumption of soy foods has been recognized to lower the risk of CVD, and phytochemicals in soy are believed to contribute to the health benefits. Glyceollin is one of the candidate phytochemicals synthesized in stressed soy that may account for many unique biological activities. In this study, the in vivo cholesterol-lowering effect of glyceollins was investigated. Male golden Syrian hamsters were fed diets including (1) 36 kcal% fat diet, (2) 36 kcal% fat diet containing 250 mg/kg diet glyceollins, or (3) chow for 28 days. Hepatic cholesterol esters and free cholesterol, hepatic total lipid content, plasma lipoproteins, fecal bile acid, fecal total cholesterol, and cholesterol metabolism related gene expressions were measured. Glyceollin supplementation led to significant reduction of plasma VLDL, hepatic cholesterol esters, and total lipid content. Consistent with changes in circulating cholesterol, glyceollin supplementation also altered expression of the genes related to cholesterol metabolism in the liver. In contrast, no change in plasma LDL and HDL, fecal bile acid, or cholesterol content was observed. The cholesterol-lowering effect of glyceollins appeared not to go through the increase of bile excretion. These results supported glyceollins' role as novel soy-derived cholesterol-lowering phytochemicals that may contribute to soy's health effects.

Effects of short term fasting on the expression of genes involved in lipid metabolism in chicks

The aim of this study was to analyze the expression patterns of key genes involved in lipid metabolism in response to short term fasting in chicks (Gallus gallus). The mRNA level of the genes was analyzed after 0, 2, and 4 h of fasting in the liver and white adipose tissue. In the liver, the mRNA level of peroxisome proliferator-activated receptor α was significantly increased after 2 h of fasting. The mRNA levels of carnitine palmitoyltransferase 1a and acyl-CoA oxidase were significantly increased after 4 h of fasting. In contrast, the mRNA levels of sterol regulatory element-binding protein 1, acetyl-CoA carboxylase α, and fatty acid synthase were significantly decreased after 4 h of fasting. The mRNA levels of cholesterol metabolism-related genes such as 3-hydroxy-3-methylglutaryl-CoA reductase and cholesterol 7α-hydroxylase were significantly decreased after 4 h of fasting. In the white adipose tissue, the mRNA level of adipose triglyceride lipase was significantly increased after 4 h of fasting. In contrast, the mRNA levels of peroxisome proliferator-activated receptor γ and lipoprotein lipase were significantly decreased after 4 h of fasting. These results demonstrated that the gene expression of lipid metabolism-related genes is regulated by short term fasting in both the liver and WAT in chicks.

Coffee polyphenols exert hypocholesterolemic effects in zebrafish fed a high-cholesterol diet

BackgroundHypercholesterolemia is an important risk factor for the development of coronary artery disease. Some dietary polyphenols, such as coffee polyphenols (CPPs), reduce cholesterol levels. The mechanism of this cholesterol-lowering effect is not fully understood, although 5-CQA, a major component of CPPs, reportedly inhibits cholesterol biosynthesis. Here, we investigated the mechanism of the cholesterol-lowering effect of CPPs on the basis of cholesterol metabolism–related gene expression in the liver. We also examined the effects of CPPs on vascular lipid accumulation in zebrafish with high cholesterol diet–induced hypercholesterolemia.MethodsOver 14 weeks, adult zebrafish were fed a control diet, a high-cholesterol diet, or the latter diet supplemented with CPPs. To measure the extent of vascular lipid accumulation, for 10 days larval zebrafish (which are optically transparent) were fed these same diets with the addition of a fluorescent cholesteryl ester.ResultsIn adult zebrafish, addition of CPPs to a high-cholesterol diet significantly suppressed the increase in plasma and liver cholesterol levels seen when fish ingested the same diet lacking CPPs. Transcription levels of the liver genes hmgcra (encoding 3-hydroxy-3-methylglutaryl-coenzyme A reductase A, a rate-limiting enzyme in cholesterol biosynthesis) and mtp (encoding microsomal triglyceride transfer protein, a lipid transfer protein required for assembly and secretion of lipoproteins) were significantly lower in fish fed the CPP-containing diet than in fish fed the unsupplemented high-cholesterol diet. In contrast, the expression level of the liver gene cyp7a1a (encoding the cytochrome P450 polypeptide 1a of subfamily A of family 7, a rate-limiting enzyme for bile acid biosynthesis) increased significantly upon consumption of the CPP-containing diet. In larval fish, accumulation of fluorescently labeled cholesterol in the caudal artery was greatly reduced on the CPP-containing diet.ConclusionsCPP ingestion suppressed cholesterol accumulation in the plasma, liver, and vascular system of zebrafish. Downregulation of cholesterol and lipoprotein synthesis and upregulation of bile acid synthesis in the liver may be the fundamental underlying mechanisms by which CPPs exert their hypocholesterolemic effects. CPP intake may help prevent and manage hypercholesterolemia in humans, and further investigations along these lines using a variety of CPP dose rates are warranted.

Anti-obesity Effect of Alkaline Reduced Water in High Fat-Fed Obese Mice

Whether or not alkaline reduced water (ARW) has a positive effect on obesity is unclear. This study aims to prove the positive effect of ARW in high-fat (HF) diet-induced obesity (DIO) in C57BL/6 mice model. Toward this, obesity was induced by feeding the C57BL/6 male mice with high-fat diet (w/w 45% fat) for 12 weeks. Thereafter, the animals were administered with either ARW or tap water. Next, the degree of adiposity and DIO-associated parameters were assessed: clinico-pathological parameters, biochemical measurements, histopathological analysis of liver, the expression of cholesterol metabolism-related genes in the liver, and serum levels of adipokine and cytokine. We found that ARW-fed mice significantly ameliorated adiposity: controlled body weight gain, reduced the accumulation of epididymal fats and decreased liver fats as compared to control mice. Accordingly, ARW coordinated the level of adiponectin and leptin. Further, mRNA expression of cytochrome P450 (CYP)7A1 was upregulated. In summary, our data shows that ARW intake inhibits the progression of HF-DIO in mice. This is the first note on anti-obesity effect of ARW, clinically implying the safer fluid remedy for obesity control.

Hepatitis B virus induces expression of cholesterol metabolism-related genes via TLR2 in HepG2 cells.

To investigate whether hepatitis B virus (HBV) exacerbates hepatic cholesterol accumulation, and explore the underlying mechanisms. HepG2 cells were infected with adenovirus (Ad) containing 1.3-fold overlength HBV genome. Real-time polymerase chain reaction and Western blotting were used to measure mRNA and protein expression of target genes. Cholesterol accumulation was measured by fluorescence microscopy. Cell toxicity due to Ad-HBV treatment was determined by the mitochondrial tetrazolium assay. The protein levels of toll-like receptors (TLRs) were determined by Western blotting. Ad-HBV increased hepatic cholesterol accumulation and enhanced the mRNA and protein levels of low-density lipoprotein receptor (LDLR) and 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMGCoAr) mRNA and protein expression in HepG2 cells. In addition, these inductive effects were partly offset by suppressing TLR2 expression levels by small interfering RNA in HepG2 cells. Ad-HBV increases LDLR and HMGCoAr expression, resulting in exacerbated cholesterol accumulation in HepG2 cells, which was mediated via the TLR2 pathway.

The joint effect of cigarette smoking and polymorphisms on LRP5, LEPR, near MC4R and SH2B1 genes on metabolic syndrome susceptibility in Taiwan

Metabolic syndrome (MetS) is a combination of medical disorders, consisting of multiple, interrelated risk factors of metabolic origin. To investigate the associations of MetS with appetite-related genes (LEPR, near MC4R and SH2B1) and cholesterol metabolism-related gene (LRP5) polymorphism variants and the joint effect of cigarette smoking and these polymorphism variants on MetS in a community-based case-control study. Metabolic syndrome was defined according to the American Heart Association and National Heart Lung Blood Institute (AHA/NHLBI) criteria. A total of 237 MetS cases and 202 subjects without MetS aged 40 or over in Taiwan were analyzed. The genotypes of LRP5-rs3736228, LEPR-rs1137100, near MC4R-rs17782313 and SH2B1-rs4788102 were analyzed by the PCR-restriction fragment length polymorphism method. A strong association of the SNP rs17782313 near MC4R gene with MetS susceptibility was found. The data indicated that the C allele of near MC4R-rs17782313 is an obvious risk factor for MetS susceptibility. The joint effects of cigarette smoking and susceptible genotypes of LRP5, LEPR, near MC4R or SH2B1 genes led to a relatively higher risk of having MetS. Using subjects with the wild-type of LRP5, LEPR, near MC4R or SH2B1 genes and without a smoking habit as a reference group, those with cigarette smoking (current and former) and more than one variant type had a 4.1-fold (95 % CI = 1.6-10.2) risk of having MetS. The genotypes of the appetite-related genes (LEPR, near MC4R and SH2B1) and cholesterol metabolism-related gene (LRP5), together with a cigarette smoking habit, are important risk factors for MetS.

Hypocholesterolemia of Rhizoma Coptidis alkaloids is related to the bile acid by up-regulated CYP7A1 in hyperlipidemic rats

This study is to investigate the cholesterol-lowering effect and the new mode of action of coptis alkaloids on high lipid diet-induced hyperlipidemic rats. Coptis alkaloids extract (CAE) was prepared by alcohol extraction from Rhizoma Coptidis that have been quality-controlled according to the protocol. The cholesterol-lowering effect of CAE was evaluated on SD rats fed with high-lipid diet. Serum level of lipid, Bile acid and cholesterol in the liver and feces of the rats were measured using colorimetric assay kit. RT-PCR and Western blot were used to analyze the mRNA and protein expression of cholesterol metabolism-related genes including cholesterol 7α-hydroxylase (CYP7A1), peroxisome proliferator-activated receptor-alpha (PPARα) and farnesoid X receptor (FXR) in the livers of the rats. A HPLC analysis was used to assess the activity of CYP7A1. The results showed that CAE reduced the levels of serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C). CYP7A1 gene expression and its activity was up-regulated dose-dependently acompanying with the increased level of bile acid and the reduced cholesterol level in the livers of the CAE treated hyperlipidemic rats. Meanwhile, the mRNA expression of PPARα was also up-regulated in dose-dependent way acompanying the down-modulation of the FXR mRNA expression in the livers of the CAE treated hyperlipidemic rats.The results indicate that the cholesterol-lowering effect of coptis alkaloid extract is at least partly attributed to its promoting the cholesterol conversion into bile acids by up-regulating the gene expression of CYP7A1 and thus increasing its activity in the liver of the hyperlipidemic rats, which might related to the positive regulation of PPARα and the negative modulation of FXR.

Dietary soy protein induces hepatic lipogenic enzyme gene expression while suppressing hepatosteatosis in obese female Zucker rats bearing DMBA-initiated mammary tumors

Fatty liver is associated with obesity and breast cancer. We used an obese rat model of mammary cancer to examine whether hepatosteatosis is modifiable by diet and associated with altered expression of hepatic lipogenic enzyme genes, thyroid hormone system genes and cholesterol metabolism-related genes. Beginning at the age of 5weeks, lean and obese female Zucker rats were fed high-isoflavone soy protein- or casein (control protein)-containing diets. Rats were euthanized at 200days of age [corresponding to 147days after administration of carcinogen to induce mammary tumors; (Hakkak et al. in, Oncol Lett 2:29-36, 2011)]. Obese rats had a greater degree of liver steatosis than lean rats. Obese casein-fed rats had marked steatosis with small foci of mononuclear infiltration, whereas obese soy protein-fed rats had a significantly lower steatosis index. Comparisons between lean and obese casein-fed rats showed that obesity was associated with significant reductions in hepatic mRNA abundance for Glucose 6-Phosphate Dehydrogenase (G6PD), 6-Phosphogluconate Dehydrogenase (6PGD), Thyroid Receptor Alpha 1 (TRα1), Thyroid Receptor Beta 1 (TRβ1) and Iodothyronine Deiodinase 1 (DIO1). The soy protein diet was associated with increased expression of Fatty Acid Synthase (FASN), Malic Enzyme 1 (ME1), 6PGD, Sterol Regulatory Element Binding Protein-1c (SREBP-1c) and SREBP-2 genes in the livers of obese but not lean rats. Western blot analysis showed a significant induction of ME1 protein expression in the livers of obese, soy protein-fed rats, which paralleled the increased serum insulin level in this group. Long-term soy protein consumption can counter hepatic steatosis while coincidently promoting hepatic lipogenic gene expression, the latter likely a consequence of elevated serum insulin. We suggest that elevations in serum insulin, hepatic lipogenesis and cholesterol synthesis all contributed to the increased tumorigenesis previously observed for the obese, soy protein-fed rats.