SREBP-1 mRNA Research Articles

Bilirubin Increases Insulin Sensitivity by Regulating Cholesterol Metabolism, Adipokines and PPARγ Levels.

Obesity can cause insulin resistance and type 2 diabetes. Moderate elevations in bilirubin levels have anti-diabetic effects. This study is aimed at determining the mechanisms by which bilirubin treatment reduces obesity and insulin resistance in a diet-induced obesity (DIO) mouse model. DIO mice were treated with bilirubin or vehicle for 14 days. Body weights, plasma glucose, and insulin tolerance tests were performed prior to, immediately, and 7 weeks post-treatment. Serum lipid, leptin, adiponectin, insulin, total and direct bilirubin levels were measured. Expression of factors involved in adipose metabolism including sterol regulatory element-binding protein (SREBP-1), insulin receptor (IR), and PPARγ in liver were measured by RT-PCR and Western blot. Compared to controls, bilirubin-treated mice exhibited reductions in body weight, blood glucose levels, total cholesterol (TC), leptin, total and direct bilirubin, and increases in adiponectin and expression of SREBP-1, IR, and PPARγ mRNA. The improved metabolic control achieved by bilirubin-treated mice was persistent: at two months after treatment termination, bilirubin-treated DIO mice remained insulin sensitive with lower leptin and higher adiponectin levels, together with increased PPARγ expression. These results indicate that bilirubin regulates cholesterol metabolism, adipokines and PPARγ levels, which likely contribute to increased insulin sensitivity and glucose tolerance in DIO mice.

Effects on Liver Lipid Metabolism of the Naturally Occurring Dietary Flavone Luteolin-7-glucoside.

Disruptions in whole-body lipid metabolism can lead to the onset of several pathologies such as nonalcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVDs). The present study aimed at elucidating the molecular mechanisms behind the lipid-lowering effects of the flavone luteolin-7-glucoside (L7G) which we previously showed to improve plasma lipid profile in rats. L7G is abundant in plant foods of Mediterranean diet such as aromatic plants used as herbs. Results show that dietary supplementation with L7G for one week induced the expression of peroxisome proliferator-activated receptor-alpha (PPAR-α) and of its target gene carnitine palmitoyl transferase 1 (CPT-1) in rat liver. L7G showed a tendency to decrease the hepatic expression of sterol regulatory element-binding protein-1 (SREBP-1), without affecting fatty acid synthase (FAS) protein levels. Although SREBP-2 and LDLr mRNA levels did not change, the expression of HMG CoA reductase (HMGCR) was significantly repressed by L7G. L7G also inhibited this enzyme's in vitro activity in a dose dependent manner, but only at high and not physiologically relevant concentrations. These results add new evidence that the flavone luteolin-7-glucoside may help in preventing metabolic diseases and clarify the mechanisms underlying the beneficial health effects of diets rich in fruits and vegetables.

고콜레스테롤 식이 투여 마우스에서 복분자 미숙과 추출물과 홍삼농축액 복합 투여의 콜레스테롤 개선 효과

본 연구는 복분자 미숙과 물 추출물과 홍삼농축액으로 C57BL/6J 수컷 마우스를 이용하여 콜레스테롤 억제 효과 및 지질대사에 미치는 영향을 살펴보고, 기능성 식품으로의 가능성을 알아보았다. 실험동물은 C57BL/6J 수컷 마우스를 사용하였으며, 12주 동안 고콜레스테롤 식이를 급여하면서 복분자 미숙과 물 추출물과 홍삼농축액을 경구투여 하였다. 그 결과로 고콜레스테롤 식이군과 비교하였을 때 복분자 미숙과 추출물과 홍삼농축액 식이군에서 체중증가량, 식이섭취량에는 변화가 없었다. 콜레스테롤 합성의 가장 중요한 기작인 LDL receptor와 SREBP2 발현에서는 복분자 미숙과 추출물 투여군과 복분자와 홍삼 복합 투여군 모두 유의적으로 증가하여 세포 안으로의 LDL 흡수를 촉진시킴으로써 체내 콜레스테롤을 낮추는 것으로 판단된다. HDL 관련 유전자 발현에서도 복분자 미숙과 추출물 투여군과 복분자와 홍삼 복합 투여군에서 HDL uptake 유전자인 SR-B1의 발현을 증가시켜 콜레스테롤 개선 효과를 보였다. 또한 간의 형태학적 변화에서는 고콜레스테롤 식이군과 비교하였을 때 복분자 미숙과 물 추출물과 홍삼농축액 복합 투여군에서 지방 형성이 현저히 줄어들었고, leptin과 FAS의 농도를 측정한 결과 유의적으로 감소하였다. 결과적으로 복분자 미숙과 물 추출물과 홍삼농축액 복합 투여가 콜레스테롤과 고지혈증 예방에 긍정적인 효과를 보일 것으로 사료된다.

Positive regulations of adipogenesis by Italian ryegrass [Lolium multiflorum] in 3T3-L1 cells.

Back groundIntramuscular fat deposition in the meat animal is relatively new strategy for developing the meat quality. Fat deposition is largely depending on the adipocyte proliferation and differentiation. Therefore, we investigated the effect of chloroform extract of L. multiflorum [CELM] on cell proliferation, lipid accumulation and adipocyte differentiation in 3T3-L1 cells and body weight of mouse.ResultsWe identified 6,9-Octadecatrienoic acid, Hexadecanoic acid, 2-hydroxypropanoic acid, butane-2,3-diol and hexane-1,2,3,4,5,6-hexaol in CELM. L. multiflorum extract increased the cell viability, lipid accumulation, cell cycle progression and key transcriptional and secretory factors like PPRAγ2, C/CEBP-α, adiponectin, aP2, GLUT-4, FAS and SREBP-1 mRNA expression as compared with control cells. For in-vivo, mice administered with CELM significantly increased body weight throughout the experiment periods. Further, the identified fatty acids like 3, 6, 9-Octadecatrienoic acid and Hexadecanoic acid was docked with target protein [PPRAγ2] using HEX 6.12. The least binding energy considered as high affinity with target protein. The maximum affinity with the target protein was observed in the Hexadecanoic acid followed by 3, 6, 9-Octadecatrienoic acid. The binding efficacy of Hexadecanoic acid and 3, 6, 9-Octadecatrienoic acid to the active site of PPAR-γ2 may be enhanced the adipocyte differentiations.ConclusionThese findings suggest that CELM stimulates adipogenesis via activating the PPARγ-mediated signaling pathway in adipocyte which could be useful for the development of meat quality in animals.

Abstract 636: The Nuclear Receptor FXR Uncouples the Actions of Srebp2 and MiR-33

The role of microRNAs in fine-tuning gene expression has now been well established, but the mechanisms for microRNA regulation at the transcriptional level remain understudied. The physiologic context in which microRNAs are acting is likely linked to the function of these same microRNAs and how they are regulated. Here we identify miR-33 as a direct target gene of the bile acid nuclear receptor FXR. We show that pharmacologic FXR activation induces miR-33 in wild-type, but not FXR knockout mice. MiR-33 is located in the Srebp2 locus, and we show that FXR activation also induces the expression of Srebp2 mRNA. Using ChIP-Seq, we identify at least one functional FXRE in an intronic region of Srebp2, demonstrating that miR-33 and Srebp2 are both direct FXR targets. Although FXR activation increases Srebp2 mRNA levels, we also demonstrate that FXR in fact decreases Srebp2 proteolytic processing, which determines its transcriptional activity. This decreased activity is a result of the FXR dependent induction of the integral ER membrane protein Insig2, which is itself also a direct FXR target. Together these results identify a molecular mechanism for the transcriptional regulation of Srebp2 and miR-33, as well as the mechanism for the decreased activity of Srebp2 processing in the ER by FXR. The best characterized target of miR-33 is ABCA1. We have previously demonstrated that FXR activation decreases ABCA1 protein levels via the induction of miR-144, a microRNA that also targets ABCA1. Our new findings suggest that FXR induces two independent microRNAs that function together to repress ABCA1 and reduce HDL levels.

Lipid-Modulating Effects of Aqueous Extract of Rubus Occidentalis in Hepatocarcinoma HepG2 Cells

Little knowledge exists on the lipid-modulating effect of Rubus occidentalis (RO). The present study investigated the molecular mechanisms of lipid-modulating effects of aqueous extract of RO (ROW) in hepatocarcinoma HepG2 cells. ROW decreased apolipoprotein B100 (ApoB100)/apolipoprotein A-1 (ApoA-1) ratio. ROW increased the expression of LDL-receptor (LDL-R). ROW decreased the gene expression of sterol regulatory element-binding protein 1c (SREBP-1c) as well as fatty acid synthase in a concentration-dependent manner. ROW not only down-regulated gene expression of SREBP-2 and HMG-CoA synthase mRNA expression, but also inhibited HMG-CoA reductase activity in a concentration-dependent manner (IC50 = 240.6 μg/ml). These results indicate that ROW decreases the level of bad cholesterol and increases good cholesterol levels by lowering the gene expression of transcription factors, SREBP-1c and SREBP-2, and by inhibiting the expression and/or activity of their downstream enzymes such as fatty acid synthase and HMG-CoA synthase and reductase.

Ameliorative effect of Pracparatum mungo extract on high cholesterol diets in hamsters

This study was designed to test the lipid-lowering and antioxidative activities of Pracparatum mungo extract (PME), in comparison to its components berberine and glycyrrhizin in cholesterol-fed hamsters. The PME and berberine significantly lowered the atherogenic index compared to glycyrrhizin and the control (P < 0.05). The hepatic HMG-CoA reductase activity was significantly lower in the PME and berberine groups than in the glycyrrhizin group (P < 0.05), while the hepatic ACAT activity was significantly decreased by all treatments with respect to the high cholesterol fed group (P < 0.05). The overall potential of the antioxidant system was significantly enhanced by the PME, berberine and glycyrrhizin supplements as the plasma and hepatic TBARS levels were lowered while the hepatic superoxide dismutase activity and glutathione levels, HMG-CoA reductase, LDL receptor, PPAR, SREBP-2 and CYP7A1 mRNA expressions were increased by the treatments of PME and berberine in comparison with the high cholesterol fed hamsters (P < 0.05). Collectively, these results suggest that the supplementation of PME, berberine and glycyrrhizin increased antioxidant activity in hamsters. Furthermore, we observed that PME and berberine groups promoted the excretion of neutral and acidic sterols (P < 0.05), that could contribute to explain the lower plasma and hepatic cholesterol levels found in the treated animals.

Resveratrol attenuates hepatic steatosis in high-fat fed mice by decreasing lipogenesis and inflammation

ObjectiveResveratrol (RSV) is the most studied natural compound that activates sirtuins, which produce beneficial metabolic effects on lipid and glucose metabolism. The aim of the present study was to investigate the role of resveratrol in preventing nonalcoholic fatty liver disease (NAFLD) and expression of liver inflammatory markers in mice treated with a high-fat diet. Methods and proceduresEighteen male mice were divided into three groups and fed for 60 d with a standard diet (ST), high-fat diet (HFD), or high-fat diet plus resveratrol (HFD + RSV, 30 mg/kg/d). Body weight, food intake, and serum total cholesterol, triacylglycerol, insulin, alanine transaminase (ALT), and aspartate aminotransferase (AST) were evaluated. Liver histology was analyzed. Expression of ACC, PPAR-γ, ChREBP, SREBP-1 c, CPT-1, tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), NF-κB, interleukin 1 β (IL-1 β), and SIRT1 were evaluated by quantitative real-time reverse transcriptase PCR (qRT-PCR). ResultsThe major finding of the present study was that RSV reduced body fat, total cholesterol, triacylglycerol, transaminases, and insulin plasma level. These results were accompanied with a significant reduction in TNF-α, IL-6, and NF-κB mRNA expression in the liver. Analyses of liver adipogenesis related genes indicated that ACC, PPAR-γ, and SREBP-1 mRNA expression were significantly suppressed in HFD + RSV mice. In addition, we observed increased expression of SIRT1 in the HFD + RSV group. ConclusionsWe observed that treatment with resveratrol improved lipid metabolism, and decreased NAFLD and pro-inflammatory profile in liver of mice with obesity-inducible diets. These data suggest an important clinical application of RSV in preventing liver diseases.

Conservation of lipid metabolic gene transcriptional regulatory networks in fish and mammals

Lipid content and composition in aquafeeds have changed rapidly as a result of the recent drive to replace ecologically limited marine ingredients, fishmeal and fish oil (FO). Terrestrial plant products are the most economic and sustainable alternative; however, plant meals and oils are devoid of physiologically important cholesterol and long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic (EPA), docosahexaenoic (DHA) and arachidonic (ARA) acids. Although replacement of dietary FO with vegetable oil (VO) has little effect on growth in Atlantic salmon (Salmo salar), several studies have shown major effects on the activity and expression of genes involved in lipid homeostasis. In vertebrates, sterols and LC-PUFA play crucial roles in lipid metabolism by direct interaction with lipid-sensing transcription factors (TFs) and consequent regulation of target genes. The primary aim of the present study was to elucidate the role of key TFs in the transcriptional regulation of lipid metabolism in fish by transfection and overexpression of TFs. The results show that the expression of genes of LC-PUFA biosynthesis (elovl and fads2) and cholesterol metabolism (abca1) are regulated by Lxr and Srebp TFs in salmon, indicating highly conserved regulatory mechanism across vertebrates. In addition, srebp1 and srebp2 mRNA respond to replacement of dietary FO with VO. Thus, Atlantic salmon adjust lipid metabolism in response to dietary lipid composition through the transcriptional regulation of gene expression. It may be possible to further increase efficient and effective use of sustainable alternatives to marine products in aquaculture by considering these important molecular interactions when formulating diets.

Overexpressing TNF-Alpha in Pancreatic Ductal Adenocarcinoma Cells and Fibroblasts Modifies Cell Survival and Reduces Fatty Acid Synthesis via Downregulation of Sterol Regulatory Element Binding Protein-1 and Activation of Acetyl CoA Carboxylase

The effect of tumor necrosis factor-alpha (TNF-α) gene delivery has been suggested as a potentially useful therapeutic approach to improve the chemotherapeutic treatment of patients with pancreatic ductal adenocarcinoma (PDA), but the exact mechanism of its action is not clearly understood. In this study, we analyzed the expression profile of TNF-α in PDA tissue and explored its potential role in fatty acid synthase (FAS) regulation in PDA cells and in fibroblasts. Quantitative real-time polymerase chain reaction was used to examine the expression of TNF-α in PDA, matching adjacent tissues, and benign lesions. Logistic regression models with robust variance were used to analyze the gene expression levels, and Kaplan–Meier survival curves were generated. In vitro, we overexpressed the TNF-α gene in PDA cells and fibroblasts and analyzed its effect on cell survival, migration, and on members of the FAS signaling pathway. We also evaluated TNF-α effects on a panel of inflammation-, angiogenesis-, and metastasis-related markers. In the tumor tissue of PDA patients, compared with their matched adjacent tissue, expression levels of TNF-α were not statistically different and did not correlate with survival or any other examined clinicopathological features. Overexpression of TNF-α significantly (p < 0.05) reduced PDA and fibroblast cell migration. In PDA cells that highly overexpress TNF-α, this was associated with a significant reduction of FAS mRNA and protein expression levels and significant (p < 0.05) reduction of SREBP-1 and ACC mRNA. Reduction of FAS by TNF-α was inhibited when either SREBP-1 or ACC was knocked down by siRNA. PDA cells and fibroblasts that overexpress TNF-α displayed differential regulation of several inflammation-related markers and reduced levels of metastasis-related genes. Our data demonstrate a previously unknown multi-targeted involvement of TNF-α in PDA lipogenesis and inflammation and metastasis and suggest that intratumoral introduction of TNF-α may have the potential as a novel therapeutic approach in human PDA.

Effects of small interfering RNA-mediated hepatic glucagon receptor inhibition on lipid metabolism in db/db mice

Hepatic glucose overproduction is a major characteristic of type 2 diabetes. Because glucagon is a key regulator for glucose homeostasis, antagonizing the glucagon receptor (GCGR) is a possible therapeutic strategy for the treatment of diabetes mellitus. To study the effect of hepatic GCGR inhibition on the regulation of lipid metabolism, we generated siRNA-mediated GCGR knockdown (si-GCGR) in the db/db mouse. The hepatic knockdown of GCGR markedly reduced plasma glucose levels; however, total plasma cholesterol was increased. The detailed lipid analysis showed an increase in the LDL fraction, and no change in VLDL HDL fractions. Further studies showed that the increase in LDL was the result of over-expression of hepatic lipogenic genes and elevated de novo lipid synthesis. Inhibition of hepatic glucagon signaling via siRNA-mediated GCGR knockdown had an effect on both glucose and lipid metabolism in db/db mice.

The inhibitory effect of black soybean on hepatic cholesterol accumulation in high cholesterol and high fat diet-induced non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is defined as excess of fat in the liver. We investigated the effects of black soybean on the cholesterol metabolism and insulin resistance of mice fed high cholesterol/fat diets. Mice were randomly allocated into four groups that were fed different diets: the normal cholesterol/fat diet; high cholesterol/fat diets (HCD); and HCD with 1%, and 4% black soybean powder (1B-HCD, and 4B-HCD). Liver total cholesterol and triglyceride concentrations were significantly lower in the black soybean-supplemented groups than that in the HCD group. PCR revealed significantly lower hepatic SREBP2 and HMG-CoA reductase mRNA levels of black soybean-supplemented mice. Real-time PCR revealed significantly higher hepatic ABCA1 mRNA level of black soybean-supplemented mice, which may increase cholesterol efflux. Liver bile acids concentration was significantly high in the 4B-HCD group. Black soybean stimulated secretion of adiponectin, activation of pAMPK, and eliminated free fatty acids in the liver. Black soybean supplementation decreased MDA and nitrate level. The activities of SOD, catalase, and GPx were restored by black soybean supplementation. Our data strongly indicate that black soybean influences the balance between oxidative and antioxidative stress. We suggest that black soybean improves cholesterol metabolism, insulin resistance, and alleviates oxidative damage in NAFLD.

Comparison of in vivo effects of insulin on SREBP-1c activation and INSIG-1/2 in rat liver and human and rat adipose tissue

The stimulatory effects of insulin on de novo lipogenesis (DNL) in the liver, where it is an important contributor to non-alcoholic fatty liver disease (NAFLD), hepatic and systemic insulin resistance, is strong and well established. In contrast, insulin plays only a minor role in DNL in adipose tissue. The reason why insulin stimulates DNL more in liver than in fat is not known but may be due to differential regulation of the transcription and post-translational activation of sterol regulatory element binding proteins (SREBPs). To test this hypothesis, we have examined effects of insulin on activation of SREBP-1c in liver of rats and in adipose tissue of rats and human subjects. Liver and epidydimal fat were obtained from alert rats and subcutaneous adipose tissue from human subjects in response to 4 h euglycemic-hyperinsulinemic clamps.Here we show that acutely raising plasma insulin levels in rats and humans increased SREBP-1 mRNA comparably 3-4 fold in rat liver and rat and human adipose tissue, but increased post-translational activation of SREBP-1c only in rat liver, while decreasing it in adipose tissue. These differential effects of insulin on SREBP-1c activation in liver and adipose tissue were associated with robust changes in the opposite direction of INSIG-1 and to a lesser extent of INSIG-2 mRNA and proteins.We conclude that these findings support the hypothesis that insulin stimulated activation of SREBP-1c in the liver, at least in part, by suppressing INSIG-1 and -2, whereas in adipose tissue, an increase in INSIG-1 and -2 prevented SREBP-1c activation.

Lipid Regulators during Atherogenesis: Expression of LXR, PPAR, and SREBP mRNA in the Human Aorta

Transcription factors LXRs, PPARs, and SREBPs have been implicated in a multitude of physiological and pathological processes including atherogenesis. However, little is known about the regulation of these transcription factors at different stages of atherosclerosis progression. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to compare the contents of mRNAs in pairs intact-injured aorta fragments taken from the same donors. Only minor changes in LXRα, LXRβ, PPARα, PPARγ, SREBP1, and SREBP2 mRNA levels were found in initial lesions as compared with intact non-diseased tissue. The contents of all mRNAs but SREBP2 mRNA were found to be progressively up-regulated in fatty streaks and fibrous lipoid plaques. These changes were only partially reproduced in cultured macrophages upon lipid loading. Wave-shaped changes in abundance of correlations between given group of mRNAs and 28 atherosclerosis-related mRNA species in the course of atherogenesis were observed. The impact of specific mRNA correlations on the total correlations also significantly varied between different lesion types. The study suggests that the extent and forms of LXR/PPAR/SREBP participation in intima functions vary nonlinear in individual fashion in atherogenesis. We speculate that the observed changes in mRNAs expression and coupling reflect shifts in lipid ligands availability and cellular composition in the course of atherosclerosis progression.

Activation of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase during high fat diet feeding

The liver plays a central role in regulating cholesterol homeostasis. High fat diets have been shown to induce obesity and hyperlipidemia. Despite considerable advances in our understanding of cholesterol metabolism, the regulation of liver cholesterol biosynthesis in response to high fat diet feeding has not been fully addressed. The aim of the present study was to investigate mechanisms by which a high fat diet caused activation of liver 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) leading to increased cholesterol biosynthesis. Mice were fed a high fat diet (60% kcal fat) for 5weeks. High fat diet feeding induced weight gain and elevated lipid levels (total cholesterol and triglyceride) in both the liver and serum. Despite cholesterol accumulation in the liver, there was a significant increase in hepatic HMG-CoA reductase mRNA and protein expression as well as enzyme activity. The DNA binding activity of sterol regulatory element binding protein (SREBP)-2 and specific protein 1 (Sp1) were also increased in the liver of mice fed a high fat diet. To validate the in vivo findings, HepG2 cells were treated with palmitic acid. Such a treatment activated SREBP-2 as well as increased the mRNA and enzyme activity of HMG-CoA reductase leading to intracellular cholesterol accumulation. Inhibition of Sp1 by siRNA transfection abolished palmitic acid-induced SREBP-2 and HMG-CoA reductase mRNA expression. These results suggest that Sp1-mediated SREBP-2 activation contributes to high fat diet induced HMG-CoA reductase activation and increased cholesterol biosynthesis. This may play a role in liver cholesterol accumulation and hypercholesterolemia.

918 Overexpressing TNF-Alpha in Pancreatic Ductal Adenocarcinoma Cells and Fibroblasts Modifies Cell Survival and Reduces Fatty Acid Synthesis via Downregulation of Sterol Regulatory Element Binding Protein-1 and Activation of Acetyl CoA Carboxylase

The effect of tumor necrosis factor-alpha (TNF-α) gene delivery has been suggested as a potentially useful therapeutic approach to improve the chemotherapeutic treatment of patients with pancreatic ductal adenocarcinoma (PDA), but the exact mechanism of its action is not clearly understood. In this study, we analyzed the expression profile of TNF-α in PDA tissue and explored its potential role in fatty acid synthase (FAS) regulation in PDA cells and in fibroblasts. Quantitative real-time polymerase chain reaction was used to examine the expression of TNF-α in PDA, matching adjacent tissues, and benign lesions. Logistic regression models with robust variance were used to analyze the gene expression levels, and Kaplan–Meier survival curves were generated. In vitro, we overexpressed the TNF-α gene in PDA cells and fibroblasts and analyzed its effect on cell survival, migration, and on members of the FAS signaling pathway. We also evaluated TNF-α effects on a panel of inflammation-, angiogenesis-, and metastasis-related markers. In the tumor tissue of PDA patients, compared with their matched adjacent tissue, expression levels of TNF-α were not statistically different and did not correlate with survival or any other examined clinicopathological features. Overexpression of TNF-α significantly (p < 0.05) reduced PDA and fibroblast cell migration. In PDA cells that highly overexpress TNF-α, this was associated with a significant reduction of FAS mRNA and protein expression levels and significant (p < 0.05) reduction of SREBP-1 and ACC mRNA. Reduction of FAS by TNF-α was inhibited when either SREBP-1 or ACC was knocked down by siRNA. PDA cells and fibroblasts that overexpress TNF-α displayed differential regulation of several inflammation-related markers and reduced levels of metastasis-related genes. Our data demonstrate a previously unknown multi-targeted involvement of TNF-α in PDA lipogenesis and inflammation and metastasis and suggest that intratumoral introduction of TNF-α may have the potential as a novel therapeutic approach in human PDA.

Dual probiotic strains suppress high fructose-induced metabolic syndrome

To investigate the effect of novel probiotics on the clinical characteristics of high-fructose induced metabolic syndrome. Male Wistar rats aged 4 wk were fed a 70% w/w high-fructose diet (n = 27) or chow diet (n = 9) for 3 wk to induce metabolic syndrome, the rats were then randomized into groups and administered probiotic [Lactobacillus curvatus (L. curvatus) HY7601 and Lactobacillus plantarum (L. plantarum) KY1032] at 10(9) cfu/d or 10(10) cfu/d or placebo by oral gavage for 3 wk. Food intake and body weight were measured once a week. After 6 wk, the rats were fasted for 12 h, then anesthetized with diethyl ether and sacrificed. Blood samples were taken from the inferior vena cava for plasma analysis of glucose, insulin, C-peptide, total-cholesterol, triglycerides and thiobarbituric acid-reacting substances. Real-time polymerase chain reaction was performed using mouse-specific Taqman probe sets to assess genes related to fatty acid β-oxidation, lipogenesis and cholesterol metabolism in the liver. Target gene expression was normalized to the housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase. Rodents fed a high-fructose diet developed clinical characteristics of the metabolic syndrome including increased plasma glucose, insulin, triglycerides, total cholesterol and oxidative stress levels, as well as increased liver mass and liver lipids compared to chow fed controls. Probiotic treatment (L. curvatus HY7601 and L. plantarum KY1032) at high (10(10) cfu/d) or low dosage (10(9) cfu/d) lowered plasma glucose, insulin, triglycerides and oxidative stress levels. Only high-dose probiotic treatment reduced liver mass and liver cholesterol. Probiotic treatment reduced lipogenesis via down-regulation of SREBP1, FAS and SCD1 mRNA levels and increased β-oxidation via up-regulation of PPARα and CPT2 mRNA levels. Probiotic L. curvatus HY7601 and L. plantarum KY1032 combined suppressed the clinical characteristics of high-fructose-induced metabolic syndrome, therefore, may provide a natural alternative for the treatment of diet-induced metabolic syndrome.

Lipopolysaccharide downregulates CD91/low-density lipoprotein receptor-related protein 1 expression through SREBP-1 overexpression in human macrophages

Sterol regulatory element-binding proteins (SREBPs) negatively modulate the expression of the CD91/low-density lipoprotein receptor-related protein (LRP1), a carrier and signaling receptor that mediates the endocytosis of more than 40 structurally and functionally distinct ligands. The aim of this work was to analyze whether lipopolysaccharide (LPS) can regulate LRP1 expression through SREBPs in human monocyte-derived macrophages (HMDM). LPS led to LRP1 mRNA and protein inhibition in a dose- and time-dependent manner. Concomitantly, a strong upregulation of SREBP-1 mRNA and SREBP-1 nuclear protein levels was observed in LPS-treated HMDM. The specific silencing of SREBP-1 efficiently prevented LRP1 reduction caused by LPS. SREBP-1 mRNA and nuclear protein levels remained high in HMDM treated with LPS unexposed or exposed to LDL. Native (nLDL) or aggregated LDL (agLDL) per se downregulated SREBP-2 expression levels and increased LRP1 expression. However, lipoproteins did not significantly alter the effect of LPS on SREBP-1 and LRP1 expression. Collectively, these data support that lipoproteins and LPS exert their modulatory effect on LRP1 expression through different SREBP isoforms, SREBP-2 and SREBP-1, respectively. These results highlight a crucial role of SREBP-1 as a mediator of the downregulatory effects of LPS on LRP1 expression in human macrophages, independently of the absence or presence of modified lipoproteins.

422 Accelerated Adipose Tissue Dysfunction and Cardiovascular Risk in Individuals of South Asian Ethnicity

BackgroundIndividuals with similar degrees of obesity can have significantly different risks of developing metabolic diseases. We previously identified that South Asians (SA) have more cardio-metabolic risk factors compared with European caucasians (EC) matched for body mass index (BMI). In the present study, we examined whether ethnic-specific differences in adipose tissue morphology and metabolic function can account for differences in cardiovascular disease (CVD) risk between SA and EC.MethodsSubcutaneous superficial abdominal adipose tissue biopsies were obtained from 108 males and females of SA or EC descent, with a mean age of 36 years overall, and assessed for adipose tissue: (1.) morphology; (2.) functional metabolic processes, determined through gene expression profiles; and (3.) endocrine functions, measured via serum adipokine levels. All values reported are adjusted for BMI, age and sex.ResultsAdipocyte diameter was significantly greater (259±4 vs. 238±5 units, P<0.01) among SA compared with EC. SA also expressed greater levels SREBP1, TIMP1 and CD68 mRNA than EC, indicating increased lipid accumulation, decreased extracellular matrix breakdown and increased macrophage accumulation and inflammation in SA, respectively. Finally, serum adiponectin levels, were markedly lower in SA compared with EC (by 37%, P<0.001), and was associated with hyperinsulinemia and a marked 4-fold greater hepatic fat accumulation (P<0.01).ConclusionSA have evidence of adipose tissue dysfunction at a relatively early age, as demonstrated by adipocyte hypertrophy, increased lipid accumulation and inflammation and reduced adiponectin secretion compared with EC. Adipose tissue dysfunction is related to greater CVD risk factors in SA and may be the primary defect leading to accelerated CVD and associated high morbidity and mortality rates in SA.AstraZeneca BackgroundIndividuals with similar degrees of obesity can have significantly different risks of developing metabolic diseases. We previously identified that South Asians (SA) have more cardio-metabolic risk factors compared with European caucasians (EC) matched for body mass index (BMI). In the present study, we examined whether ethnic-specific differences in adipose tissue morphology and metabolic function can account for differences in cardiovascular disease (CVD) risk between SA and EC. Individuals with similar degrees of obesity can have significantly different risks of developing metabolic diseases. We previously identified that South Asians (SA) have more cardio-metabolic risk factors compared with European caucasians (EC) matched for body mass index (BMI). In the present study, we examined whether ethnic-specific differences in adipose tissue morphology and metabolic function can account for differences in cardiovascular disease (CVD) risk between SA and EC. MethodsSubcutaneous superficial abdominal adipose tissue biopsies were obtained from 108 males and females of SA or EC descent, with a mean age of 36 years overall, and assessed for adipose tissue: (1.) morphology; (2.) functional metabolic processes, determined through gene expression profiles; and (3.) endocrine functions, measured via serum adipokine levels. All values reported are adjusted for BMI, age and sex. Subcutaneous superficial abdominal adipose tissue biopsies were obtained from 108 males and females of SA or EC descent, with a mean age of 36 years overall, and assessed for adipose tissue: (1.) morphology; (2.) functional metabolic processes, determined through gene expression profiles; and (3.) endocrine functions, measured via serum adipokine levels. All values reported are adjusted for BMI, age and sex. ResultsAdipocyte diameter was significantly greater (259±4 vs. 238±5 units, P<0.01) among SA compared with EC. SA also expressed greater levels SREBP1, TIMP1 and CD68 mRNA than EC, indicating increased lipid accumulation, decreased extracellular matrix breakdown and increased macrophage accumulation and inflammation in SA, respectively. Finally, serum adiponectin levels, were markedly lower in SA compared with EC (by 37%, P<0.001), and was associated with hyperinsulinemia and a marked 4-fold greater hepatic fat accumulation (P<0.01). Adipocyte diameter was significantly greater (259±4 vs. 238±5 units, P<0.01) among SA compared with EC. SA also expressed greater levels SREBP1, TIMP1 and CD68 mRNA than EC, indicating increased lipid accumulation, decreased extracellular matrix breakdown and increased macrophage accumulation and inflammation in SA, respectively. Finally, serum adiponectin levels, were markedly lower in SA compared with EC (by 37%, P<0.001), and was associated with hyperinsulinemia and a marked 4-fold greater hepatic fat accumulation (P<0.01). ConclusionSA have evidence of adipose tissue dysfunction at a relatively early age, as demonstrated by adipocyte hypertrophy, increased lipid accumulation and inflammation and reduced adiponectin secretion compared with EC. Adipose tissue dysfunction is related to greater CVD risk factors in SA and may be the primary defect leading to accelerated CVD and associated high morbidity and mortality rates in SA.AstraZeneca SA have evidence of adipose tissue dysfunction at a relatively early age, as demonstrated by adipocyte hypertrophy, increased lipid accumulation and inflammation and reduced adiponectin secretion compared with EC. Adipose tissue dysfunction is related to greater CVD risk factors in SA and may be the primary defect leading to accelerated CVD and associated high morbidity and mortality rates in SA.

Beneficial Metabolic Effects of CB1R Anti-Sense Oligonucleotide Treatment in Diet-Induced Obese AKR/J Mice

An increasing amount of evidence supports pleiotropic metabolic roles of the cannibinoid-1 receptor (CB1R) in peripheral tissues such as adipose, liver, skeletal muscle and pancreas. To further understand the metabolic consequences of specific blockade of CB1R function in peripheral tissues, we performed a 10-week-study with an anti-sense oligonucleotide directed against the CB1R in diet-induced obese (DIO) AKR/J mice. DIO AKR/J mice were treated with CB1R ASO Isis-414930 (6.25, 12.5 and 25 mg/kg/week) or control ASO Isis-141923 (25 mg/kg/week) via intraperitoneal injection for 10 weeks. At the end of the treatment, CB1R mRNA from the 25 mg/kg/week CB1R ASO group in the epididymal fat and kidney was decreased by 81% and 63%, respectively. Body weight gain was decreased in a dose-dependent fashion, significantly different in the 25 mg/kg/week CB1R ASO group (46.1±1.0 g vs veh, 51.2±0.9 g, p<0.05). Body fat mass was reduced in parallel with attenuated body weight gain. CB1R ASO treatment led to decreased fed glucose level (at week 8, 25 mg/kg/week group, 145±4 mg/dL vs veh, 195±10 mg/dL, p<0.05). Moreover, CB1R ASO treatment dose-dependently improved glucose excursion during an oral glucose tolerance test, whereas control ASO exerted no effect. Liver steatosis was also decreased upon CB1R ASO treatment. At the end of the study, plasma insulin and leptin levels were significantly reduced by 25 mg/kg/week CB1R ASO treatment. SREBP1 mRNA expression was decreased in both epididymal fat and liver. G6PC and fatty acid translocase/CD36 mRNA levels were also reduced in the liver. In summary, CB1R ASO treatment in DIO AKR/J mice led to improved insulin sensitivity and glucose homeostasis. The beneficial effects of CB1R ASO treatment strongly support the notion that selective inhibition of the peripheral CB1R, without blockade of central CB1R, may serve as an effective approach for treating type II diabetes, obesity and the metabolic syndrome.