Total Saponins of Dioscorea Mitigate Nonalcoholic Steatohepatitis in Mice by Regulating AMPK/SREBP-1c/ACC Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo investigate the role and mechanism of total saponins of Dioscorea （TSD） in mitigating nonalcoholic steatohepatitis （NASH） in mice. MethodForty-eight C57BL/6J mice were randomized into a normal group and a modeling group. The mice for modeling were fed with a high-fat and high-cholesterol diet + 20% fructose solution for 16 weeks and randomized into model， atorvastatin （4 mg·kg-1·d-1）， and high-， medium-， and low-dose （200， 60， and 20 mg·kg-1·d-1） TSD groups. The mice were administrated with corresponding doses of drugs by gavage for 8 weeks. The mouse activity， liver index， levels of total cholesterol （TC）， triglycerides （TG）， and free fatty acids （FFAs） in the liver， and levels of TC， TG， aspartate aminotransferase （AST）， alanine aminotransferase （ALT）， γ-glutamyl transferase （GGT）， interleukin-1β （IL-1β）， and tumor necrosis factor-α （TNF-α） in the serum were measured. Hematoxylin-eosin staining， Masson staining， oil red O staining， and transmission electron microscopy were employed to observe the pathological changes， lipid accumulation， and morphological changes of liver ultrastructure. Western blot was employed to determine the protein levels of AMP-activated protein kinase （AMPK）， sterol regulatory element-binding protein-1c （SREBP-1c）， acetyl-CoA carboxylase （ACC）， and phosphorylated ACC （p-ACC） in the liver tissue. ResultCompared with the normal group, the activity of mice in the model group decreased(P<0.05， P<0.01), the levels of TC, TG, FFA and serum TC, TG, ALT, AST, GGT, IL-1β and TNF-α, liver coefficient and liver pathology scores were significantly increased, the expression of p-AMPK/AMPK and p-ACC proteins in liver tissues was significantly reduced, and the expressions of SREBP-1c and ACC proteins were significantly increased (P<0.01). Compared with the model group， atorvastatin increased the mouse activity （P<0.05）， while each dose of TSD caused no significant changed in the mouse activity. The levels of TC, TG, FFA in liver and serum TC, TG, ALT, AST, GGT, IL-1β, TNF-α, liver coefficient and liver pathological score in TSD and atorvastatin groups were significantly decreased, and the expressions of p-AMPK/AMPK and p-ACC in liver tissue were significantly increased. The expressions of SREBP-1c and ACC were significantly decreased (P<0.05,P<0.01). ConclusionTSD may alleviate NASH in mice by regulating the AMPK/SREBP-1c/ACC signaling pathway to reduce lipid synthesis.

α-Hederin Regulates SREBP1/FASN Pathway and Inhibits Malignant Phenotype of Non-small Cell Lung Cancer / 肿瘤防治研究

Objective To explore the regulative effect of α-Hederin on the proliferation and invasion of NSCLC and investigate its related molecular mechanism. Methods After A549 and HCC-1833 cells were treated with a concentration gradient of α-Hederin for 24 and 48 h, the OD450nm was detected by using CCK8 assays, and the IC50 was calculated.The A549 and HCC-1833 cells were divided into the blank control and α-Hederin groups in accordance with IC50 values.Cell proliferation was detected by EdU assays, and cell cycle transformation and cell apoptosis were detected by flow cytometry.Cell mobility was detected by using Transwell and scratch assays.SREBP1 and FASN protein expression levels were detected through Western blot analysis, and cell lipid accumulation was detected via oil red O staining. Results The survival rate of lung cancer cells decreased significantly with the increase of α-Hederin concentration, and the IC50 values of A549 and HCC-1833 cells at 48 h were 15 and 25 μg/ml, respectively.Compared with the blank control group, cells proliferation and migration were significantly inhibited, cells were blocked in the G1/S phase, the apoptosis rate increased, and the protein expression and lipid accumulation of SREBP1/FASN significantly reduced after α-Hederin treatment. Conclusion α-Hederin can inhibit the proliferation and migration, G1/S phase transition and induce the apoptosis of NSCLC cells and hinder the malignant progression of NSCLC by downregulating the expression of SREBP1 and FASN and reducing the accumulation of cell lipids.

Berberine mitigates nonalcoholic hepatic steatosis by downregulating SIRT1-FoxO1-SREBP2 pathway for cholesterol synthesis / 中西医结合学报

OBJECTIVE@#To investigate effects of berberine (BBR) on cholesterol synthesis in HepG2 cells with free fatty acid (FFA)-induced steatosis and to explore the underlying mechanisms.@*METHODS@#A steatosis cell model was induced in HepG2 cell line fed with FFA (0.5 mmol/L, oleic acid:palmitic acid = 2:1), and then treated with three concentrations of BBR; cell viability was assessed with cell counting kit-8 assays. Lipid accumulation in cells was observed through oil red O staining and total cholesterol (TC) content was detected by TC assay. The effects of BBR on cholesterol synthesis mediators were assessed by Western blotting and quantitative polymerase chain reaction. In addition, both silent information regulator 1 (SIRT1) and forkhead box transcription factor O1 (FoxO1) inhibitors were employed for validation.@*RESULTS@#FFA-induced steatosis was successfully established in HepG2 cells. Lipid accumulation and TC content in BBR groups were significantly lower (P < 0.05, P < 0.01), associated with significantly higher mRNA and protein levels of SIRT1(P < 0.05, P < 0.01), significantly lower sterol regulatory element-binding protein 2 (SREBP2) and 3-hydroxy 3-methylglutaryl-CoA reductase levels (P < 0.05, P < 0.01), as well as higher Acetyl-FoxO1 protein level (P < 0.05, P < 0.01) compared to the FFA only group. Both SIRT1 inhibitor SIRT1-IN-1 and FoxO1 inhibitor AS1842856 blocked the BBR-mediated therapeutic effects. Immunofluorescence showed that the increased SIRT1 expression increased FoxO1 deacetylation, and promoted its nuclear translocation.@*CONCLUSION@#BBR can mitigate FFA-induced steatosis in HepG2 cells by activating SIRT1-FoxO1-SREBP2 signal pathway. BBR may emerge as a potential drug candidate for treating nonalcoholic hepatic steatosis.

POST1/C12ORF49 regulates the SREBP pathway by promoting site-1 protease maturation

Sterol-regulatory element binding proteins (SREBPs) are the key transcriptional regulators of lipid metabolism. The activation of SREBP requires translocation of the SREBP precursor from the endoplasmic reticulum to the Golgi, where it is sequentially cleaved by site-1 protease (S1P) and site-2 protease and releases a nuclear form to modulate gene expression. To search for new genes regulating cholesterol metabolism, we perform a genome-wide CRISPR/Cas9 knockout screen and find that partner of site-1 protease (POST1), encoded by C12ORF49, is critically involved in the SREBP signaling. Ablation of POST1 decreases the generation of nuclear SREBP and reduces the expression of SREBP target genes. POST1 binds S1P, which is synthesized as an inactive protease (form A) and becomes fully mature via a two-step autocatalytic process involving forms B'/B and C'/C. POST1 promotes the generation of the functional S1P-C'/C from S1P-B'/B (canonical cleavage) and, notably, from S1P-A directly (non-canonical cleavage) as well. This POST1-mediated S1P activation is also essential for the cleavages of other S1P substrates including ATF6, CREB3 family members and the α/β-subunit precursor of N-acetylglucosamine-1-phosphotransferase. Together, we demonstrate that POST1 is a cofactor controlling S1P maturation and plays important roles in lipid homeostasis, unfolded protein response, lipoprotein metabolism and lysosome biogenesis.

The regulation mechanism of HCBP6 mimic phosphorylation on triglyceride synthesis in hepatocytes / 西安交通大学学报(医学版)

【Objective】 To investigate the regulation of HCBP6 mimic phosphorylation on triglyceride synthesis in hepatocytes so as to provide a molecular target for the treatment of metabolism-associated fatty liver disease. 【Methods】 We used site-directed mutagenesis to mimic constitutive phosphorylation and dephosphorylation of HCBP6 Ser-10 and Ser-151. Oil red O staining and triglyceride content determination were used to detect triglyceride levels in hepatocytes. The expressions of SREBP1c, ACC1 and FASN were detected by qRT-PCR and Western blotting. The Dual-Luciferase Report Gene System was used to detect SREBP1c promoter activity. 【Results】 HCBP6 Ser-10 phosphorylation promoted triglyceride synthesis. HCBP6 Ser-10 phosphorylation upregulated the expressions of SREBP1c, ACC1and FASN genes; HCBP6 Ser-10 phosphorylation enhanced the SREBP1c promoter activity. 【Conclusion】 HCBP6 Ser-10 phosphorylation can significantly enhance the activity of the SREBP1c promoter, upregulate the SREBP1c-FASN signal pathway transduction, and promote the synthesis of triglycerides.

The SREBP (Sterol Regulatory Element-Binding Protein) pathway: a regulatory bridge between carotenogenesis and sterol biosynthesis in the carotenogenic yeast Xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous is a basidiomycete yeast that naturally produces the red-orange carotenoid astaxanthin, which has remarkable antioxidant properties. The biosynthesis of carotenoids and sterols share some common elements that have been studied in X. dendrorhous. For example, their synthesis requires metabolites derived from the mevalonate pathway and in both specific pathways, cytochrome P450 enzymes are involved that share a single cytochrome P450 reductase, CrtR, which is essential for astaxanthin biosynthesis, but is replaceable for ergosterol biosynthesis. Research on the regulation of carotenoid biosynthesis is still limited in X. dendrorhous; however, it is known that the Sterol Regulatory Element-Binding Protein (SREBP) pathway, which is a conserved regulatory pathway involved in the control of lipid metabolism, also regulates carotenoid production in X. dendrorhous. This review addresses the similarities and differences that have been observed between mammal and fungal SREBP pathways and what it is known about this pathway regarding the regulation of the production of carotenoids and sterols in X. dendrorhous.

Discovery of a potent FKBP38 agonist that ameliorates HFD-induced hyperlipidemia

The mammalian target of rapamycin (mTOR)-sterol regulatory element-binding proteins (SREBPs) signaling promotes lipogenesis. However, mTOR inhibitors also displayed a significant side effect of hyperlipidemia. Thus, it is essential to develop mTOR-specific inhibitors to inhibit lipogenesis. Here, we screened the endogenous inhibitors of mTOR, and identified that FKBP38 as a vital regulator of lipid metabolism. FKBP38 decreased the lipid content

Effect of fucoxanthin on insulin resistance in obese mice induced by high fat diet / 中国中药杂志

The aim of this paper was to study the effect and mechanism of fucoxanthin on insulin resistance of obese mice induced by high-fat diet. Fifty C57 BL/6 J male mice were randomly divided into control group and high-fat diet group. The insulin resistance model was induced with high-fat diet for 12 weeks, and model mice were randomly divided into model group, fucoxanthin-0.2% group, fucoxanthin-0.4% group and metformin group. After dietary treatment for 6 weeks, the body weight and epididymal fat weight in each group were measured. Fasting blood glucose(FBG), fasting insulin(FINS), total cholesterol(TC), triglyceride(TG), low-density lipoprotein(LDL-C) and high-density lipoprotein(HDL-C) were measured, and insulin resistance index(HOMA-IR) was calcula-ted. The pathological morphology in liver was observed by hematoxylin eosin staining, and the expressions of some key proteins in insulin receptor substrate 1(IRS-1)/posphoinositide 3-kinase(PI3 K)/serine-threonine kinase(Akt) and peroxisome proliferators-activated receptor-γ(PPARγ)/sterol regulatory element binding protein-1(SREBP-1)/fatty acid synthetase(FAS) pathways in liver were detected by Western blot. According to the findings, compared with the model group, levels of body weight, epididymal fat weight, FBG, FINS, TC, TG, LDL-C and HOMA-IR, as well as protein expressions of PPARγ, SREBP-1 and FAS in liver were significantly reduced(P<0.05 or P<0.01), while level of HDL-C and protein expressions of p-IRS-1, IRS-1, PI3 K and p-Akt in liver were signi-ficantly increased after treatment with fucoxanthin(P<0.05 or P<0.01). And the pathological changes of liver tissue in fucoxanthin-treated mice were also improved obviously. The results showed that fucoxanthin could improve obesity, hyperglycemia and hyperlipidemia, and alleviate insulin resistance in obese mice, and its mechanism is possibly related to the regulation of IRS-1/PI3 K/Akt and PPARγ/SREBP-1/FAS pathways.

NF- B/HDAC1/SREBP1c pathway mediates the inflammation signal in progression of hepatic steatosis

The transcription factor nuclear factor kappa B (NF-B) is activated in hepatocytes in the pathogenesis of hepatic steatosis. However, the action mechanism of NF-B remains to be established in the hepatic steatosis. In this study, the subunit of NF-B was found to promote the hepatic steatosis through regulation of histone deacetylase 1 (HDAC1) in hepatocytes. The activity was supported by the phenotypes of knockout (-KO) mice and knockout (-KO) mice. Hepatic steatosis was reduced in the -KO mice, but not in the -KO mice. The reduction was a result of inhibition of HDAC1 activity in the -KO cells. Knockdown of gene led to suppression of hepatocyte steatosis in HepG2 cells. A decrease in sterol-regulatory element binding protein 1c (SREBP1c) protein was observed in the liver of -KO mice and in cell with knockdown. The decrease was associated with an increase in succinylation of SREBP1c protein. The study suggests that stabilizes HDAC1 to support the SREBP1c activity in hepatic steatosis in the pathophysiological condition. Interruption of this novel pathway in the -KO, but not the -KO mice, may account for the difference in hepatic phenotypes in the two lines of transgenic mice.

Novel mechanisms underlying anti-polycystic ovary like syndrome effects of electroacupuncture in rats: suppressing SREBP1 to mitigate insulin resistance, mitochondrial dysfunction and oxidative stress

BACKGROUND: Acupuncture, a therapy of traditional Chinese medicine, is confirmed to exert the therapeutic action on polycystic ovary syndrome (PCOS). However, the detailed therapeutic mechanisms of acupuncture in PCOS remain ambiguous. In this study, we further investigated whether electroacupuncture (EA) alleviated PCOS-like symptoms in rats via regulating a metabolic regulator, sterol regulatory element binding protein-1 (SREBP1). Methods: The PCOS-like rat model was built by hypodermic injection with dehydroepiandrosterone (DHEA). The rats were subjected to EA intervention (ST29 and SP6 acupuncture points) for 5 weeks. Primary granulosa cells were isolated from control and PCOS-like rats for evaluating insulin resistance, mitochondrial dysfunction and oxidative stress in vitro. RESULTS: The expression of SREBP1 was increased in PCOS-like rats, which was suppressed by EA treatment. In addition, lentivirus-mediated overexpression of SREBP1 restrained EA treatment-induced improvement in pathological changes, serum hormone levels and insulin resistance in rats. In addition, overexpression of SREBP1 repressed insulin-stimulated phosphorylation of insulin receptor ß (IR) and AKT in primary granulosa cells. Moreover, upregulation of SREBP1 further exacerbated mitochondrial dysfunction and oxidative stress in granulosa cells isolated from PCOS-like rats. Mechanically, EA treatment suppressed SREBP1 expression through inducing the activation of AMP-activated protein kinase (AMPK) signaling pathway in PCOS-like rats. CONCLUSION: EA intervention alleviated PCOS-like symptoms in rats via improving IR, mitochondrial dysfunction and oxidative stress through regulating SREBP1, a lipid metabolism regulator. Our findings illuminate the novel protective mechanisms of EA in the treatment of PCOS.

Effect of Sulgidduk containing pine needle juice on lipid metabolism in high fat-cholesterol diet induced dyslipidemic rats / 한국영양학회지

PURPOSE: Dyslipidemia is a major risk factor for cardiovascular disease. Pine needles (Pinus densiflora seib et Zucc) are a traditional medicine used to treat dyslipidemia in clinical settings. This study examined the potential effects of sulgidduk, a Korean traditional rice cake containing pine needle juice to protect against dyslipidemia induced by a high-fat/sugidduk diet in a rat model. METHODS: Twenty one male Sprague-Dawley rats were divided randomly into three groups: normal control (NC), Sulgidduk diet (SD), Sulgidduk diet containing pine needle juice (PSD). The blood lipid levels, production of lipid peroxide in the plasma and liver, total cholesterol and triglyceride in the liver and feces, antioxidant enzyme activities in plasma and erythrocytes were measured to assess the effects of PSD on dyslipidemia. RESULTS: A high-fat/Sulgidduk diet induced dyslipidemia, which was characterized by significantly altered lipid profiles in the plasma and liver. The food intake was similar in the three groups, but weight gain and food efficiency ratio (FER) were reduced significantly in the PSD group compared to those in the SD group. The level of total cholesterol, LDL-cholesterol and TBARS in the plasma showed tendencies to decrease in the PSD group compared to those in the SD group. The levels of high-fat/Sulgidduk diet-induced sterol regulatory element-binding protein 2 (SREBP2) gene expression were reduced significantly in the PSD group. The supplementation of PSD reduced the hepatic triglyceride and total cholesterol levels significantly, and enhanced the fecal excretion of triglyceride and hepatic antioxidant enzyme activities compared to the SD group. CONCLUSION: These results suggest that the addition of 0.4% pine needle juice to Sulgidduk may be an alternative snack to control dyslipidemia.

Intervention effects and mechanism of Chinese herbal medicine of supplementing Qi and activating blood circulation on chronic intermittent hypoxia composite insulin resistance ApoE~(-/-) mice model / 中国中药杂志

This study aims to observe the intervention effects of Chinese herbal medicine of supplementing Qi and activating blood circulation on chronic intermittent hypoxia(CIH) composite insulin resistance(IR) mediated atherosclerosis(AS) mice model,and to observe the mechanism of SREBP-1 c signaling molecule.IR Apo E-/-mice model was induced by high-fat diet combined with STZ injection.Then the mice were treated with hypoxic animal incubator for 8 h per day and 8 weeks to establish a CIH+IR-ApoE-/-mouse model.Model mice were randomly and averagely divided into normoxic control group(NC),model group(CIH) and SREBPs inhibitor group(betulin),atorvastatin group(WM),TCM low-dose group(TCM-L),TCM middle-dose group(TCM-M) and TCM high-dose group(TCM-H) group.Chinese herbal medicine of supplementing Qi and activating blood circulation including ginsenosides combined with ligustrazine(TMP) were used as intervention drugs.The study observed the effect of drugs on IR,serum lipid,inflammation,stress,AS and SREBP-1 c related molecules.The results showed that fasting blood glucose in TCM-H group decreased compared with other experimental groups(P<0.05).HDL-C level in betulin group,WM group,TCM-H group was higher than that in CIH group(P<0.05).LDL-C level in TCM-M group,TCM-H group is lower than that in CIH group(P<0.05).The level of CRP in CIH group was higher than that in other groups(P<0.05).The level of SOD in TCM-H group was higher than that in CIH group(P<0.05).NC group and CIH group showed obvious AS aortic plaque,while betulin group,WM group,TCM-H group showed reduction in AS plaque(P<0.05).For descending aorta,AS plaque in CIH group was multiple and large,while less and smaller in WM group and TCM-H(P<0.05).The expression of SREBP-1 c and FAS in aorta and skeletal muscle in TCM-H group was lower than that in CIH group(P<0.05).In aorta,the expression of TNF-α and CD106(VCAM-1) was lower in TCM-H group than that in CIH group(P<0.05).In aorta,skeletal muscle and liver,the level of p-IRS-1 in TCM-H group was significantly higher than that in CIH group(P<0.05).In aorta and liver,the expression of HIF-1α in TCM-H group was lower than that in CIH group(P<0.05).The study demonstrated that combination ginsenosides with TMP could improve IR and serum lipid level and inhibit inflammation and oxidative stress as well as ultimately alleviate AS to some extent.And the mechanism of its interventional effects might be related to the inhibition of CIH-induced upregulation of SREBP-1 c related molecules.

RASAL1 induces to downregulate the SCD1, leading to suppression of cell proliferation in colon cancer via LXRα/SREBP1c pathway

BACKGROUND: Recent studies have confirmed that RASAL1 has an antitumor effect in many cancers, but its functional role and the molecular mechanism underlying in colon cancer has not been investigated. RESULTS: We collected human colon cancer tissues and adjacent non-tumor tissues, human colon cancer cell lines LoVo, CaCo2, SW1116, SW480 and HCT-116, and normal colonic mucosa cell line NCM460. RT-qPCR was used to detect the RASAL1 level in the clinical tissues and cell lines. In LoVo and HCT-116, RASAL1 was artificially overexpressed. Cell viability and proliferation were measured using CCK-8 assays, and cell cycle was detected via PI staining and flow cytometry analysis. RASAL1 significantly inhibited the cell proliferation via inducing cell cycle arrest, suppressed cell cycle associated protein expression, and decreased the lipid content and inhibited the SCD1 expression. Moreover, SCD1 overexpression induced and downregulation repressed cell proliferation by causing cell cycle arrest. Additionally, luciferase reporter assays were performed to confirm the direct binding between SREBP1c, LXRα; and SCD1 promoter, we also demonstrated that RASAL1 inhibit SCD1 3'-UTR activity. RASAL1 inhibited tumor growth in xenograft nude mice models and shows inhibitory effect of SCD1 expression in vivo. CONCLUSION: Taken together, we concluded that RASAL1 inhibited colon cancer cell proliferation via modulating SCD1 activity through LXRα/SREBP1c pathway.

Protective effects of N-acetyl-L-cysteine against binge drinking-induced fatty liver in mice / 中华劳动卫生职业病杂志

Objective@#To investigate the roles of N-acetyl-L-cysteine (NAC) against binge drinking-induced fatty liver in mice.@*Methods@#SPF male C57BL/6 mice were randomly divided into 3 groups, i.e. control group, model group, and NAC/ethanol group (n=10). Mice in model and NAC/ethanol groups were exposed to 3 doses of ethanol (6 g/kg bw) to induced fatty liver, while mice in control group received equal volume and equal energy of maltodextrin solution. NAC was administered to mice at 1 h before ethanol exposure (100 mg/kg bw, i.p.). The mice were sacrificed at 6 h after the last ethanol exposure. The liver and epididymal adipose tissues were collected. Histopathological examination and biochemical assay kit were used to evaluate the fat accumulation, while Western-blot was performed to detect the protein levels of some key factors involved in fat metabolism in liver and adipose tissues.@*Results@#Compored with control group mice, the liver index and liver weight were significantly increased compared with model group, the liver index and TG level in NAC/ethanol group mice were all significantly decreased (P<0.05). Histological examination showed NAC effectively suppressed binge drinking-induced fat accumulation in mice liver. In addition, NAC had no significant effects on the protein levels of peroxisome proliferator-activated receptor-α (PPAR-α), Acy-CoA oxidase (ACOX), sterol regulatory element binding protein 1 c (SREBP-1c) and fatty acid synthase (FAS). Furthermore, the protein levels of hormone sensitive lipase (HSL) did not significantly differ among 3 groups, whereas NAC prevented binge drinking-induced increase of HSL phosphorylation at ser563 and ser660.@*Conclusion@#NAC could effectively attenuate binge drinking-induced fatty liver, which might be associated with the inhibition of lipid mobilization by suppressing the phosphorylation of HSL.

Effect of Eletroacupuncture Intervention on Insulin Resistance, Lipid Metabolic Disorder and Expression of Hepatic SREBP-1 c and Fatty Acid Synthase Proteins in Rats with Hyperlipidemia / 针刺研究

OBJECTIVE: To observe the effect of electroacupuncture(EA) of "Fenglong" (ST 40) and "Sanyinjiao" (SP 6) on lipid metabolic disorder, insulin resistance (IR) and expression of sterol regulatory element blinding protein-1 (SREBP-1) c and fatty acid synthase (FAS) proteins in the liver tissue in hyperlipidemia rats with IR, so as to reveal its mechanisms underlying improvement of IR. METHODS: Forty male SD rats were randomly divided into blank control, model, medication and EA groups (n＝8 in each group). The IR model was established by feeding the rat with high-fat diet. Rats of the medication group were treated by intragastric administration of pioglitazone (10 mL/kg). For rats of the EA group, EA (2 Hz/100 Hz，1 mA) was applied to bilateral ST 40 and SP 6, once daily for 14 days. The insulin sensitivity index (ISI) was assessed by calculating 60－120 min glucose infusion rate (GIR 60－120) with euglycemic hyperinsulinemic clamp in reference to Kraegen's and colleagues' methods. Fasting blood samples (10 mL) were collected and analyzed for fasting blood glucose (FBG) using enzyme method, serum fasting insulin(FINS) using ELISA, free fatty acid(FFA) using spectrophotometry, and total triglyceride(TG) and total cholesterol(TC) employing glycerine phosphate oxidase peroxidase (GPO-PAP) assay, low density lipoprotein(LDL), high density lipoprotein(HDL) levels using combined filiter paper activity and lipase activity methods, respectively. The IR level was assessed by calculating homeostatic model assessment of insulin resistance (HOMA-IR) using the formula (FBG×FINS)/22.5. The expression levels of SREBP-1 c and FAS proteins in the liver tissue were detected by Western blot. RESULTS: Following modeling, the GIR 60－120 and serum HDL were significantly decreased(P0.05). CONCLUSION: EA intervention is able to improve the disorder of lipid metabolism of IR rats, which may be associated with its effects in reducing the expression of SREBP-1 c and FAS proteins and in lowering the synthesis of fatty acid.

Acción de flavonoides sobre la conversión de ácidos grasos poliinsaturados de cadena larga a partir de ácidos grasos esenciales / Action of flavonoids on conversion of long chain polyunsaturated fatty acids from essential fatty acids

RESUMEN Estudios epidemiológicos y clínicos han reportado múltiples beneficios a partir de la ingesta de ácidos grasos poliinsaturados de cadena larga n-3 (AGPI-CL n-3) EPA (ácido eicosapentaenoico) y DHA (ácido docosahexaenoico), sin embargo, la sobreexplotación de los recursos marinos limita su disponibilidad actual y futura. El ácido alfa-linolénico (ALA) es precursor metabólico de AGPI-CL n-3, por tanto su consumo es una alternativa a considerarse. No obstante, la conversión de ALA hacia EPA y DHA no es eficiente. Por otra parte, antioxidantes como los flavonoides incrementan la concentración sérica y tisular de AGPI-CL n-3, aunque los mecanismos subyacentes no están completamente dilucidados. Se explora la acción de los AGPI y flavonoides sobre el metabolismo de los AGPI-CL n-3, al modular factores de transcripción como los proliferadores de peroxisomas alfa (PPAR-α), la proteína de unión a los elementos regulatorios de esteroles (SREBP-1) y la expresión génica de las enzimas ácido graso desaturasas delta 5 (Δ5) y delta 6 (Δ6). También se recogen otras hipótesis que explicarían el incremento de AGPI n-3, como la acción antioxidante ejercida por los flavonoides y sus metabolitos.

ABSTRACT Epidemiological and clinical studies have reported multiple benefits from the intake of Long Chain Polyunsaturated Fatty Acids n-3 (LC-PUFA n-3), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid); however, overexploitation of marine sources limits current and future availability. The alpha-linolenic acid (ALA) is a metabolic precursor of PUFAs n-3-LC, therefore its consumption is an alternative to be considered. However, the conversion of ALA to EPA and DHA is not efficient. On other hand, antioxidants such as flavonoids increase serum and tissue concentration of PUFA LC n-3, although the underlying mechanisms are not fully elucidated. The effect of PUFAs and flavonoids on metabolism PUFAs n-3 LC. to modulate transcription factors such as peroxisome proliferators alpha receptor (PPAR-α), the sterol regulatory element-binding protein, (SREBP 1) and genic expression of fatty acid desaturase enzymes delta 5 (Δ5) and delta 6 (Δ6) was explored. Other hypotheses that could explain the increase of n-3 PUFAs were also included such as antioxidant action, exerted by flavonoids and their metabolites.

Research progress of sterol regulatory element binding transcription factor 1(SREBP1) in cancer / 中国肿瘤临床

The increase of fatty acid synthesis is the third biggest metabolic phenotype of tumor cells,and sterol regulatory element binding transcription factor 1(SREBP1)is the major nuclear transcription factor involved in lipid metabolism,especially in the synthesis of fatty acid.The expression of SREBP1 is elevated in multiple tumors,which plays an important role in tumor proliferation,apoptosis, invision,drug resistance,energy metabolism etc.In this paper,we will review the research progress on SREBP1 in tumor.

Effects of squalene on expression of LDLR in HepG2 cells and its mechanism / 中国药理学通报

Aim To investigate the effect of squalene on LDLR expression in HepG2 cells and its mechanism of down-regulated cholesterol. Methods The prolifer-ation of HepG2 cells exposed to squalene at different concentrations was measured by MTT assay. The effect of squalene on the expression of LDLR in HepG2 cells was measured by flow cytometry and fluorescence mi-croscopy. The effect of different concentrations of squa-lene on the interaction between SCAP and Insig2, two key protein molecules of SREBP pathway, was assayed by FRET technology. Results MTT results showed that squalene had inhibitory effect on the proliferation of HepG2 cells in a dose-dependent manner. Flow cy-tometry and fluorescence microscopy results showed that squalene enhanced LDLR expression in HepG2 cells compared with the control group. The results of FRET technology revealed that compared with model control group, the YFP fluorescence value in Squalene group dramatically declined, and the YFP fluorescence value of each drug group decreased with the range of 5~25 μmol·L-1 squalene concentration. Conclusions Squalene may promote the expression of LDLR in HepG2 cells through inhibiting the interaction between SCAP and Insig2 proteins in SREBP pathway, which may confirm that squalene is a potential novel drug for the down-regulation of cholesterol level.

Effect of Danhong injection on AMPK/SREBP-1/ACC pathways of liver in hyperlipidemic rats / 中国药理学通报

Aim To discuss the effect of Danhong in-jection(DHI) on hyperlipidemia in rats and its possible mechanism. Methods The hyperlipidemia model of rats were induced by high fat diet. The protein expres-sion of adenosine 5'-monophosphate-activated protein kinase(AMPK), p-AMPK, cholesterol-binding ele-ment binding protein (SREBP-1), adenylate-activated protein kinase carboxylasecetyl-CoA(ACC) and p-ACC in liver were detected using Western blot. Results The protein expression levels of AMPK, SREBP-1 and ACC significantly decreased (P<0.05), but the pro-tein expression levels of p-ACC and p-AMPK signifi-cantly increased (P<0.05). Conclusions Danhong injection can reduce the activity of SREBP-1 and ACC by enhancing the activation of AMPK, and effectively reduce the blood lipid level of hyperlipidemic rats by promoting fatty acid oxidation and reducing lipid depo-sition.

Changes of suppressors of cytokine signaling-3 and sterol regulatory element binding proteins-1c pathway in steatosis HepG2/HepG2.2.15 cells / 中华传染病杂志

Objective To investigate the effects of HepG2 and HepG2.2.15 cells steatosis on the mRNA and protein expressions of suppressors of cytokine signaling-3(SOCS-3) and sterol regulatory element binding proteins (SREBP-1c).Methods The cell model of chronic hepatitis B (CHB) combined with nonalcoholic fatty liver disease (NAFLD) was successfully constructed using an oleic acid-induced HepG2 and HepG2.2.15 cells steatosis.Cells were divided into HepG2 cell control group (HepG2 cell control group), HepG2.2.15 cell control group (HepG2.2.15 cell control group), HepG2 cell steatosis group (HepG2 cell steatosis group) and HepG2.2.15 cell steatosis group (HepG2.2.15 cell steatosis group).The expression levels of SOCS-3 and SREBP-1c mRNA were detected by real-time quantitative polymerase chain reaction (PCR).Changes in protein expressions of SOCS-3 and SREBP-1c were measured by western blot.Results SOCS-3 mRNA expression level in HepG2.2.15 cell control group was significantly lower than that in HepG2 cell control group (P<0.01).The level in HepG2 cell steatosis group was also significantly lower than that in HepG2 cell control group (P<0.01).However, the level of SOCS-3 mRNA in HepG2.2.15 cell steatosis group was lower than HepG2.2.15 cell control group with no statistical significance (P=0.173).There was interaction between cells and steatosis (F=25.547, P<0.01).The expression of SREBP-1c mRNA in HepG2.2.15 cell control group was significantly lower than that in HepG2 cell control group (P<0.01), and was significantly higher in HepG2.2.15 cell steatosis group than that in HepG2.2.15 cell control group (P<0.01).There was no significant difference between HepG2 cell steatosis group and HepG2 cell control group (P=1.000).There was interaction between cells and steatosis (F=5.04, P<0.05).Western blot analysis showed that protein levels of SOCS-3 and SREBP-1c in steatosis cells at 48 h and 72 h were significantly higher than those in non-alcoholic steatosis cells.Conclusions Protein expressions of SOCS-3 and SREBP-1c are up-regulated in both steatosis groups.Factorial analysis shows that there is interaction between cells and steatosis.HBV gene could inhibit SOCS-3 mRNA expression and promote the expression of SREBP-1c mRNA in steatosis cells.