BACKGROUND Gastric cancer(GC)is associated with high mortality rates.Bile acids(BAs)reflux is a well-known risk factor for GC,but the specific mechanism remains unclear.During GC development in both humans and animals...BACKGROUND Gastric cancer(GC)is associated with high mortality rates.Bile acids(BAs)reflux is a well-known risk factor for GC,but the specific mechanism remains unclear.During GC development in both humans and animals,BAs serve as signaling molecules that induce metabolic reprogramming.This confers additional cancer phenotypes,including ferroptosis sensitivity.Ferroptosis is a novel mode of cell death characterized by lipid peroxidation that contributes universally to malignant progression.However,it is not fully defined if BAs can influence GC progression by modulating ferroptosis.AIM To reveal the mechanism of BAs regulation in ferroptosis of GC cells.METHODS In this study,we treated GC cells with various stimuli and evaluated the effect of BAs on the sensitivity to ferroptosis.We used gain and loss of function assays to examine the impacts of farnesoid X receptor(FXR)and BTB and CNC homology 1(BACH1)overexpression and knockdown to obtain further insights into the molecular mechanism involved.RESULTS Our data suggested that BAs could reverse erastin-induced ferroptosis in GC cells.This effect correlated with increased glutathione(GSH)concentrations,a reduced GSH to oxidized GSH ratio,and higher GSH peroxidase 4(GPX4)expression levels.Subsequently,we confirmed that BAs exerted these effects by activating FXR,which markedly increased the expression of GSH synthetase and GPX4.Notably,BACH1 was detected as an essential intermediate molecule in the promotion of GSH synthesis by BAs and FXR.Finally,our results suggested that FXR could significantly promote GC cell proliferation,which may be closely related to its anti-ferroptosis effect.CONCLUSION This study revealed for the first time that BAs could inhibit ferroptosis sensitivity through the FXR-BACH1-GSHGPX4 axis in GC cells.This work provided new insights into the mechanism associated with BA-mediated promotion of GC and may help identify potential therapeutic targets for GC patients with BAs reflux.展开更多
非酒精性脂肪性肝炎(Non-alcoholic steatohepatitis,NASH),又称代谢性脂肪性肝炎,是病理变化与酒精性肝炎相似但无过量饮酒史的临床综合征,好发于中年特别是超重肥胖个体。非酒精性脂肪性肝炎与肥胖、胰岛素抵抗、2型糖尿病、高脂血症...非酒精性脂肪性肝炎(Non-alcoholic steatohepatitis,NASH),又称代谢性脂肪性肝炎,是病理变化与酒精性肝炎相似但无过量饮酒史的临床综合征,好发于中年特别是超重肥胖个体。非酒精性脂肪性肝炎与肥胖、胰岛素抵抗、2型糖尿病、高脂血症等代谢紊乱关系密切,主要特征为肝细胞大泡性脂肪变伴肝细胞损伤和炎症,严重者可发展为肝硬化,但至今NASH尚无得到批准的治疗方案。在寻找有效的治疗方法时,解决代谢失调、炎症和抗纤维化的新策略不断涌现。法尼类X受体(Farnesoid X receptor,FXR)除了是胆汁酸代谢和肠肝循环的关键调节剂外,还参与调节代谢稳态,使其成为NASH中有吸引力的治疗靶点。本文综述了FXR激动剂对NASH治疗的研究进展。展开更多
目的分析肝细胞法尼醇X受体(farnesoid X receptor,FXR)特异性敲除对日本血吸虫感染小鼠肠道菌群的影响。方法6~8周龄野生型雄性C57BL/6J和肝细胞FXR特异性敲除小鼠(FXR-HKO)随机分为4组:野生型小鼠正常对照组(WT,n=5)、FXR-HKO小鼠正...目的分析肝细胞法尼醇X受体(farnesoid X receptor,FXR)特异性敲除对日本血吸虫感染小鼠肠道菌群的影响。方法6~8周龄野生型雄性C57BL/6J和肝细胞FXR特异性敲除小鼠(FXR-HKO)随机分为4组:野生型小鼠正常对照组(WT,n=5)、FXR-HKO小鼠正常对照组(FXR-HKO,n=6)、野生型小鼠日本血吸虫感染组(Sj-WT,n=6)、FXR-HKO小鼠日本血吸虫感染组(Sj-FXR-HKO,n=5)。其中,感染组每只小鼠感染(15±1)条日本血吸虫尾蚴,感染第5周处死小鼠,在无菌条件下收取小鼠结肠内容物,进行16S rDNA测序,比较各组之间的肠道菌群多样性和丰度差异。结果Beta多样性分析结果显示,Sj-WT组和Sj-FXR-HKO组小鼠的肠道菌群与正常小鼠肠道菌群有明显的分群。在门水平上,与正常对照组相比,Sj-WT组和Sj-FXR-HKO组小鼠肠道中拟杆菌门的丰度升高,厚壁菌门丰度降低,厚壁菌门与拟杆菌门丰度比值明显降低(均P<0.05)。在属水平上,与正常对照组相比,日本血吸虫感染后小鼠肠道中拟杆菌属的丰度明显升高(均P<0.05),Sj-FXR-HKO组拟杆菌属的丰度比Sj-WT组的升高更明显(P<0.05),其中Sj-WT组脱硫弧菌属、杜氏菌属、乳杆菌属的丰度显著降低(均P<0.05),Sj-FXR-HKO组瘤胃球菌科属、毛罗菌科、杜氏菌属、乳杆菌属的丰度明显降低(均P<0.05)。结论肝细胞FXR特异性敲除影响了日本血吸虫感染小鼠肠道菌群稳态,为后续进一步研究FXR-肠道菌群在血吸虫病中的作用及机制奠定了扎实的实验基础。展开更多
AIM: To investigate the effect of GW4064 on the expression of adipokines and their receptors during differentiation of 3T3-L1 preadipocytes and in HepG2 cells.
Non-alcoholic fatty liver disease(NAFLD) is the hepatic manifestation of metabolic syndrome and is one of the most prevalent liver disorders worldwide. NAFLD can gradually progress to liver inflammation, fibrosis, cir...Non-alcoholic fatty liver disease(NAFLD) is the hepatic manifestation of metabolic syndrome and is one of the most prevalent liver disorders worldwide. NAFLD can gradually progress to liver inflammation, fibrosis, cirrhosis and even hepatocellular carcinoma. However, the pathogenesis of NAFLD is complex, and no efficient pharmaceutic treatments have yet been established for NAFLD. Accumulating data have shown that the farnesoid X receptor(FXR) plays important roles not only in bile acid metabolism, but also in lipid and carbohydrate homeostasis, inflammatory responses, among others. In this review, we aim to highlight the role of FXR in the pathogenesis and treatment of NAFLD.展开更多
AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfi de (H2S) generation. METHODS: The regulation of CSE expression in respons...AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfi de (H2S) generation. METHODS: The regulation of CSE expression in response to FXR ligands was evaluated in HepG2 cells and in wild-type and FXR null mice treated with 6-ethyl chenodeoxycholic acid (6E-CDCA), a synthetic FXR ligand. The analysis demonstrated an FXR responsive element in the 5'-flanking region of the human CSE gene. The function of this site was investigated by luciferase reporter assays, chromatin immunoprecipitation and electrophoretic mobility shift assays. Livers obtained from rats treated with carbon tetrachloride alone, or in combination with 6-ethyl chenodeoxycholic acid, were studied for hydrogen sulphide generation and portal pressure measurement. RESULTS: Liver expression of CSE is regulated by bile acids by means of an FXR-mediated mechanism. Western blotting, qualitative and quantitative polymerase chain reaction, as well as immunohistochemical analysis, showed that expression of CSE in HepG2 cells and in mice is induced by treatment with an FXR ligand. Administration of 6E-CDCA to carbon tetrachloride treated rats protected against the down-regulation of CSE expression, increased H2S generation, reduced portal pressure and attenuated the endothelial dysfunction of isolated and perfused cirrhotic rat livers. CONCLUSION: These results demonstrate that CSE is an FXR-regulated gene and provide a new molecular explanation for the pathophysiology of portal hypertension.展开更多
BACKGROUND: Statins are suggested to preserve gallbladder function by suppressing pro-inflammatory cytokines and preventing cholesterol accumulation in gallbladder epithelial cells. They also affect cross-talk among t...BACKGROUND: Statins are suggested to preserve gallbladder function by suppressing pro-inflammatory cytokines and preventing cholesterol accumulation in gallbladder epithelial cells. They also affect cross-talk among the nuclear hormone receptors that regulate cholesterol-bile acid metabolism in the nuclei of hepatocytes. However, there is controversy over whether or how statins change the expression of peroxisome proliferator-activated receptor(PPAR)α, PPARγ, liver X receptor α(LXRα), farnesoid X receptor(FXR), ABCG5, ABCG8, and 7α-hydroxylase(CYP7A1) which are directly involved in the cholesterol saturation index in bile. METHODS: Human Hep3B cells were cultured on dishes. MTT assays were performed to determine the appropriate concentrations of reagents to be used. The protein expression of PPARα and PPARγ was measured by Western blotting analysis, and the mRNA expression of LXRα, FXR, ABCG5, ABCG8 and CYP7A1 was estimated by RT-PCR. RESULTS: In cultured Hep3B cells, pravastatin activated PPARα and PPARγ protein expression, induced stronger expression of PPARγ than that of PPARα, increased LXRα mRNA expression, activated ABCG5 and ABCG8 mRNA expression mediated by FXR as well as LXRα, enhanced FXR mRNA expression, and increased CYP7A1 mRNA expression mediated by the PPARγ and LXRα pathways, together or independently. CONCLUSION: Our data suggested that pravastatin prevents cholesterol gallstone diseases via the increase of FXR, LXRαand CYP7A1 in human hepatocytes.展开更多
Objective To develop a high-throughput screening assay for Farnesoid X receptor （FXR） agonists based on mammalian one-hybrid system （a chimera receptor gene system） for the purpose of identifying new lead compound...Objective To develop a high-throughput screening assay for Farnesoid X receptor （FXR） agonists based on mammalian one-hybrid system （a chimera receptor gene system） for the purpose of identifying new lead compounds for dyslipidaemia drug from the chemical library. Methods cDNA encoding the human FXR ligand binding domain （LBD） was amplified by RT-PCR from a human liver total mRNA and fused to the DNA binding domain （DBD） of yeast GAL4 of pBIND to construct a GAL4-FXR （LBD） chimera expression plasmid. Five copies of the GAL4 DNA binding site were synthesized and inserted into upstream of the SV40 promoter of pGL3-promoter vector to construct a reporter plasmid pG5-SV40 Luc. The assay was developed by transient co-transfection with pG5-SV40 Luc reporter plasmid and pBIND-FXR-LBD （189-472） chimera expression plasmid. Results After optimization, CDCA, a FXR natural agonist, could induce expression of the luciferase gene in a dose-dependent manner, and had a signal/noise ratio of 10 and Z＇ factor value of 0.65, Conclusion A stable and sensitive cell-based high-throughput screening model can be used in high-throughput screening for FXR agonists from the synthetic and natural compound library.展开更多
Objective:To investigate the regulatory mechanism in liver fibrosis progression by nuclear receptor of farnesoid X receptor(FXR)and the lipid droplet-associated protein of perilipin 5(PLIN5).Methods:FXR response eleme...Objective:To investigate the regulatory mechanism in liver fibrosis progression by nuclear receptor of farnesoid X receptor(FXR)and the lipid droplet-associated protein of perilipin 5(PLIN5).Methods:FXR response element(FXRE)upstream of PLIN5 gene was found by bioinformatics,and confirmed by a dual luciferase reporter gene system;a hepatic fibrosis model based on human hepatic stellate cell LX-2 was established by induction of transforming growth factor-β1(TGF-β1);mRNA and protein levels ofα-smooth muscle actin(α-SMA)and collagen栺were measured by qPCR and Western blot after transient overexpression of FXR or PLIN5;Oil red O staining was used to study the formation of lipid droplets.Results:The promoter region of the PLIN5 gene contained a known reverse repeats-1(IR-1);the gene expression of PLIN5 in LX-2 cells was up-regulated after FXR activation(P<0.01);overexpression of PLIN5 promoted the formation of lipid droplets and significantly reduced the TGF-β1 induced fibrosis gene expression(P<0.05);FXR activation showed no effects on the inhibition of LX-2 cells activation.Conclusion:Overexpression of PLIN5 promotes the formation of lipid droplets and inhibits activation of LX-2 cells.FXR might bind to the FXRE site upstream of PLIN5 gene and regulate its gene expression.In summary,FXR may prevent liver fibrosis progression partially by regulating lipid droplet-associated protein of PLIN5.展开更多
BACKGROUND Bile acids play an important role in the amelioration of type 2 diabetes following duodenal-jejunal bypass(DJB).Serum bile acids are elevated postoperatively.However,the clinical relevance is not known.Bile...BACKGROUND Bile acids play an important role in the amelioration of type 2 diabetes following duodenal-jejunal bypass(DJB).Serum bile acids are elevated postoperatively.However,the clinical relevance is not known.Bile acids in the peripheral circulation reflect the amount of bile acids in the gut.Therefore,a further investigation of luminal bile acids following DJB is of great significance.AIM To investigate changes of luminal bile acids following DJB.METHODS Salicylhydroxamic acid(SHAM),DJB,and DJB with oral chenodeoxycholic acid(CDCA)supplementation were performed in a high-fat-diet/streptozotocininduced diabetic rat model.Body weight,energy intake,oral glucose tolerance test,luminal bile acids,serum ceramides and intestinal ceramide synthesis were analyzed at week 12 postoperatively.RESULTS Compared to SHAM,DJB achieved rapid and durable improvement in glucose tolerance and led to increased total luminal bile acid concentrations with preferentially increased proportion of farnesoid X receptor(FXR)-inhibitory bile acids within the common limb.Intestinal ceramide synthesis was repressed with decreased serum ceramides,and this phenomenon could be partially antagonized by luminal supplementation of FXR activating bile acid CDCA.CONCLUSION DJB significantly changes luminal bile acid composition with increased proportion FXR-inhibitory bile acids and reduces serum ceramide levels.There observations suggest a novel mechanism of bile acids in metabolic regulation after DJB.展开更多
Farnesoid X receptor (FXR, NR1H4) is a member of nuclear hormone receptor superfamily. Previously studies showed that FXR-/- mice spontaneously developed liver tumors when they aged, however, the relevance of which to...Farnesoid X receptor (FXR, NR1H4) is a member of nuclear hormone receptor superfamily. Previously studies showed that FXR-/- mice spontaneously developed liver tumors when they aged, however, the relevance of which to human hepatocellular carcinoma (HCC) is unclear. The aim of this study is to observe whether FXR expression is also downregulated in HCC and discuss the mechanism of the reduced FXR expression in HCC. Expression of FXR and small heterodimer partner (SHP) was measured by real-time PCR and immunohistochemical technique. Effect of pro-inflammatory cytokines on expression of FXR and its promoter activity were determined in primary hepatocytes or HepG2 and Huh7 cell lines. Our results showed that expression of FXR and its target gene SHP in human HCC was strongly downregulated compared to the normal liver tissues. In addition, pro-inflammatory cytokines were able to decrease FXR expression by inhibiting the FXR promoter activity. In conclusion this work demonstrates FXR expression is strongly downregulated in human HCC, which may be caused by decreased FXR promoter activity, suggesting a potential role of FXR in human HCC development.展开更多
OBJECTIVE Cervical cancer is the third most malignant tumor in the world.Farnesoid X receptor(FXR) is a member of nuclear receptor superfamily.It is highly expressed in liver,kidney and small intestine,while it showed...OBJECTIVE Cervical cancer is the third most malignant tumor in the world.Farnesoid X receptor(FXR) is a member of nuclear receptor superfamily.It is highly expressed in liver,kidney and small intestine,while it showed low expression level in other tissues.It not only plays an important role in the metabolism of bile acids and sugars,but also in the production of chronic inflammation in the early stage of cancer,the proliferation and migration of tumor.Compared with the normal tissue,the expression of FXR in most tumor tissues decreased.But there is no correlation between cervical cancer and FXR.So we aimed to find out the relationship between FXR and cervical cancer.METHODS A clinical study using q PCR,western blot and immunohistochemistry detected the expression of FXR in tumor tissues and normal tissues of clinical patients.FXR was activated by agonists or over-expressed by lentivirus.MTT,clone formation and flow cytometry were used to detect the relationship between FXR and proliferation of cervical cell lines.Tumor growth ability of FXR was detected by nude mice tumorigenicity.The interaction between FXR and CDKN2A-p14^(ARF)-MDM2-p53 pathway was detected by q PCR,Western blot and immunohistochemistry.RESULTS FXR was decreased in cancer tissues compared to normal control.Activation of FXR by agonist or constitutively-over-expression of FXR inhibited cervical cell proliferation.Over-expressed FXR attenuated Caski,Hela and Siha xenograft tumor growth in nude mice compared with control.Over-expression of FXR caused G1 cell-cycle arresting and up-regulated CDKN2A-p14^(ARF)-MDM2-p53 pathway.CONCLUSION FXR inhibits cervical cancer cell proliferation and cervical tumorigenicity which is related to CDKN2A-p14^(ARF)-MDM2-p53 pathway.Activation or overexpression of FXR may be a potential target for the treatment of cervical cancer.展开更多
基金Supported by the Major Basic Research Project of Natural Science Foundation of Shandong Province,No.ZR2020ZD15.
文摘BACKGROUND Gastric cancer(GC)is associated with high mortality rates.Bile acids(BAs)reflux is a well-known risk factor for GC,but the specific mechanism remains unclear.During GC development in both humans and animals,BAs serve as signaling molecules that induce metabolic reprogramming.This confers additional cancer phenotypes,including ferroptosis sensitivity.Ferroptosis is a novel mode of cell death characterized by lipid peroxidation that contributes universally to malignant progression.However,it is not fully defined if BAs can influence GC progression by modulating ferroptosis.AIM To reveal the mechanism of BAs regulation in ferroptosis of GC cells.METHODS In this study,we treated GC cells with various stimuli and evaluated the effect of BAs on the sensitivity to ferroptosis.We used gain and loss of function assays to examine the impacts of farnesoid X receptor(FXR)and BTB and CNC homology 1(BACH1)overexpression and knockdown to obtain further insights into the molecular mechanism involved.RESULTS Our data suggested that BAs could reverse erastin-induced ferroptosis in GC cells.This effect correlated with increased glutathione(GSH)concentrations,a reduced GSH to oxidized GSH ratio,and higher GSH peroxidase 4(GPX4)expression levels.Subsequently,we confirmed that BAs exerted these effects by activating FXR,which markedly increased the expression of GSH synthetase and GPX4.Notably,BACH1 was detected as an essential intermediate molecule in the promotion of GSH synthesis by BAs and FXR.Finally,our results suggested that FXR could significantly promote GC cell proliferation,which may be closely related to its anti-ferroptosis effect.CONCLUSION This study revealed for the first time that BAs could inhibit ferroptosis sensitivity through the FXR-BACH1-GSHGPX4 axis in GC cells.This work provided new insights into the mechanism associated with BA-mediated promotion of GC and may help identify potential therapeutic targets for GC patients with BAs reflux.
文摘非酒精性脂肪性肝炎(Non-alcoholic steatohepatitis,NASH),又称代谢性脂肪性肝炎,是病理变化与酒精性肝炎相似但无过量饮酒史的临床综合征,好发于中年特别是超重肥胖个体。非酒精性脂肪性肝炎与肥胖、胰岛素抵抗、2型糖尿病、高脂血症等代谢紊乱关系密切,主要特征为肝细胞大泡性脂肪变伴肝细胞损伤和炎症,严重者可发展为肝硬化,但至今NASH尚无得到批准的治疗方案。在寻找有效的治疗方法时,解决代谢失调、炎症和抗纤维化的新策略不断涌现。法尼类X受体(Farnesoid X receptor,FXR)除了是胆汁酸代谢和肠肝循环的关键调节剂外,还参与调节代谢稳态,使其成为NASH中有吸引力的治疗靶点。本文综述了FXR激动剂对NASH治疗的研究进展。
文摘目的分析肝细胞法尼醇X受体(farnesoid X receptor,FXR)特异性敲除对日本血吸虫感染小鼠肠道菌群的影响。方法6~8周龄野生型雄性C57BL/6J和肝细胞FXR特异性敲除小鼠(FXR-HKO)随机分为4组:野生型小鼠正常对照组(WT,n=5)、FXR-HKO小鼠正常对照组(FXR-HKO,n=6)、野生型小鼠日本血吸虫感染组(Sj-WT,n=6)、FXR-HKO小鼠日本血吸虫感染组(Sj-FXR-HKO,n=5)。其中,感染组每只小鼠感染(15±1)条日本血吸虫尾蚴,感染第5周处死小鼠,在无菌条件下收取小鼠结肠内容物,进行16S rDNA测序,比较各组之间的肠道菌群多样性和丰度差异。结果Beta多样性分析结果显示,Sj-WT组和Sj-FXR-HKO组小鼠的肠道菌群与正常小鼠肠道菌群有明显的分群。在门水平上,与正常对照组相比,Sj-WT组和Sj-FXR-HKO组小鼠肠道中拟杆菌门的丰度升高,厚壁菌门丰度降低,厚壁菌门与拟杆菌门丰度比值明显降低(均P<0.05)。在属水平上,与正常对照组相比,日本血吸虫感染后小鼠肠道中拟杆菌属的丰度明显升高(均P<0.05),Sj-FXR-HKO组拟杆菌属的丰度比Sj-WT组的升高更明显(P<0.05),其中Sj-WT组脱硫弧菌属、杜氏菌属、乳杆菌属的丰度显著降低(均P<0.05),Sj-FXR-HKO组瘤胃球菌科属、毛罗菌科、杜氏菌属、乳杆菌属的丰度明显降低(均P<0.05)。结论肝细胞FXR特异性敲除影响了日本血吸虫感染小鼠肠道菌群稳态,为后续进一步研究FXR-肠道菌群在血吸虫病中的作用及机制奠定了扎实的实验基础。
基金Supported by Guangdong Provincial Science and Technology Projects,No.2011B050400009Scientific Research Projects of Hubei Province Education Department,No.B2014055
文摘AIM: To investigate the effect of GW4064 on the expression of adipokines and their receptors during differentiation of 3T3-L1 preadipocytes and in HepG2 cells.
基金Supported by National Nature Science Foundation of China,No.81273727 and No.81302927Innovation Program of Shanghai Municipal Education Commission,No.14YZ054
文摘Non-alcoholic fatty liver disease(NAFLD) is the hepatic manifestation of metabolic syndrome and is one of the most prevalent liver disorders worldwide. NAFLD can gradually progress to liver inflammation, fibrosis, cirrhosis and even hepatocellular carcinoma. However, the pathogenesis of NAFLD is complex, and no efficient pharmaceutic treatments have yet been established for NAFLD. Accumulating data have shown that the farnesoid X receptor(FXR) plays important roles not only in bile acid metabolism, but also in lipid and carbohydrate homeostasis, inflammatory responses, among others. In this review, we aim to highlight the role of FXR in the pathogenesis and treatment of NAFLD.
文摘AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfi de (H2S) generation. METHODS: The regulation of CSE expression in response to FXR ligands was evaluated in HepG2 cells and in wild-type and FXR null mice treated with 6-ethyl chenodeoxycholic acid (6E-CDCA), a synthetic FXR ligand. The analysis demonstrated an FXR responsive element in the 5'-flanking region of the human CSE gene. The function of this site was investigated by luciferase reporter assays, chromatin immunoprecipitation and electrophoretic mobility shift assays. Livers obtained from rats treated with carbon tetrachloride alone, or in combination with 6-ethyl chenodeoxycholic acid, were studied for hydrogen sulphide generation and portal pressure measurement. RESULTS: Liver expression of CSE is regulated by bile acids by means of an FXR-mediated mechanism. Western blotting, qualitative and quantitative polymerase chain reaction, as well as immunohistochemical analysis, showed that expression of CSE in HepG2 cells and in mice is induced by treatment with an FXR ligand. Administration of 6E-CDCA to carbon tetrachloride treated rats protected against the down-regulation of CSE expression, increased H2S generation, reduced portal pressure and attenuated the endothelial dysfunction of isolated and perfused cirrhotic rat livers. CONCLUSION: These results demonstrate that CSE is an FXR-regulated gene and provide a new molecular explanation for the pathophysiology of portal hypertension.
文摘BACKGROUND: Statins are suggested to preserve gallbladder function by suppressing pro-inflammatory cytokines and preventing cholesterol accumulation in gallbladder epithelial cells. They also affect cross-talk among the nuclear hormone receptors that regulate cholesterol-bile acid metabolism in the nuclei of hepatocytes. However, there is controversy over whether or how statins change the expression of peroxisome proliferator-activated receptor(PPAR)α, PPARγ, liver X receptor α(LXRα), farnesoid X receptor(FXR), ABCG5, ABCG8, and 7α-hydroxylase(CYP7A1) which are directly involved in the cholesterol saturation index in bile. METHODS: Human Hep3B cells were cultured on dishes. MTT assays were performed to determine the appropriate concentrations of reagents to be used. The protein expression of PPARα and PPARγ was measured by Western blotting analysis, and the mRNA expression of LXRα, FXR, ABCG5, ABCG8 and CYP7A1 was estimated by RT-PCR. RESULTS: In cultured Hep3B cells, pravastatin activated PPARα and PPARγ protein expression, induced stronger expression of PPARγ than that of PPARα, increased LXRα mRNA expression, activated ABCG5 and ABCG8 mRNA expression mediated by FXR as well as LXRα, enhanced FXR mRNA expression, and increased CYP7A1 mRNA expression mediated by the PPARγ and LXRα pathways, together or independently. CONCLUSION: Our data suggested that pravastatin prevents cholesterol gallstone diseases via the increase of FXR, LXRαand CYP7A1 in human hepatocytes.
基金supported by the Ministry of Science and Technology, PRC in Mega-projects of Science Research During the 10th Five-Year Plan Period (No. 2004AA2Z38784)National Natural Science Foundation of China (No. 30472026).
文摘Objective To develop a high-throughput screening assay for Farnesoid X receptor （FXR） agonists based on mammalian one-hybrid system （a chimera receptor gene system） for the purpose of identifying new lead compounds for dyslipidaemia drug from the chemical library. Methods cDNA encoding the human FXR ligand binding domain （LBD） was amplified by RT-PCR from a human liver total mRNA and fused to the DNA binding domain （DBD） of yeast GAL4 of pBIND to construct a GAL4-FXR （LBD） chimera expression plasmid. Five copies of the GAL4 DNA binding site were synthesized and inserted into upstream of the SV40 promoter of pGL3-promoter vector to construct a reporter plasmid pG5-SV40 Luc. The assay was developed by transient co-transfection with pG5-SV40 Luc reporter plasmid and pBIND-FXR-LBD （189-472） chimera expression plasmid. Results After optimization, CDCA, a FXR natural agonist, could induce expression of the luciferase gene in a dose-dependent manner, and had a signal/noise ratio of 10 and Z＇ factor value of 0.65, Conclusion A stable and sensitive cell-based high-throughput screening model can be used in high-throughput screening for FXR agonists from the synthetic and natural compound library.
基金National Natural Science Foundation of China(81973376)。
文摘Objective:To investigate the regulatory mechanism in liver fibrosis progression by nuclear receptor of farnesoid X receptor(FXR)and the lipid droplet-associated protein of perilipin 5(PLIN5).Methods:FXR response element(FXRE)upstream of PLIN5 gene was found by bioinformatics,and confirmed by a dual luciferase reporter gene system;a hepatic fibrosis model based on human hepatic stellate cell LX-2 was established by induction of transforming growth factor-β1(TGF-β1);mRNA and protein levels ofα-smooth muscle actin(α-SMA)and collagen栺were measured by qPCR and Western blot after transient overexpression of FXR or PLIN5;Oil red O staining was used to study the formation of lipid droplets.Results:The promoter region of the PLIN5 gene contained a known reverse repeats-1(IR-1);the gene expression of PLIN5 in LX-2 cells was up-regulated after FXR activation(P<0.01);overexpression of PLIN5 promoted the formation of lipid droplets and significantly reduced the TGF-β1 induced fibrosis gene expression(P<0.05);FXR activation showed no effects on the inhibition of LX-2 cells activation.Conclusion:Overexpression of PLIN5 promotes the formation of lipid droplets and inhibits activation of LX-2 cells.FXR might bind to the FXRE site upstream of PLIN5 gene and regulate its gene expression.In summary,FXR may prevent liver fibrosis progression partially by regulating lipid droplet-associated protein of PLIN5.
文摘BACKGROUND Bile acids play an important role in the amelioration of type 2 diabetes following duodenal-jejunal bypass(DJB).Serum bile acids are elevated postoperatively.However,the clinical relevance is not known.Bile acids in the peripheral circulation reflect the amount of bile acids in the gut.Therefore,a further investigation of luminal bile acids following DJB is of great significance.AIM To investigate changes of luminal bile acids following DJB.METHODS Salicylhydroxamic acid(SHAM),DJB,and DJB with oral chenodeoxycholic acid(CDCA)supplementation were performed in a high-fat-diet/streptozotocininduced diabetic rat model.Body weight,energy intake,oral glucose tolerance test,luminal bile acids,serum ceramides and intestinal ceramide synthesis were analyzed at week 12 postoperatively.RESULTS Compared to SHAM,DJB achieved rapid and durable improvement in glucose tolerance and led to increased total luminal bile acid concentrations with preferentially increased proportion of farnesoid X receptor(FXR)-inhibitory bile acids within the common limb.Intestinal ceramide synthesis was repressed with decreased serum ceramides,and this phenomenon could be partially antagonized by luminal supplementation of FXR activating bile acid CDCA.CONCLUSION DJB significantly changes luminal bile acid composition with increased proportion FXR-inhibitory bile acids and reduces serum ceramide levels.There observations suggest a novel mechanism of bile acids in metabolic regulation after DJB.
基金Supported by the National Natural Science Foundation of China(30600299)
文摘Farnesoid X receptor (FXR, NR1H4) is a member of nuclear hormone receptor superfamily. Previously studies showed that FXR-/- mice spontaneously developed liver tumors when they aged, however, the relevance of which to human hepatocellular carcinoma (HCC) is unclear. The aim of this study is to observe whether FXR expression is also downregulated in HCC and discuss the mechanism of the reduced FXR expression in HCC. Expression of FXR and small heterodimer partner (SHP) was measured by real-time PCR and immunohistochemical technique. Effect of pro-inflammatory cytokines on expression of FXR and its promoter activity were determined in primary hepatocytes or HepG2 and Huh7 cell lines. Our results showed that expression of FXR and its target gene SHP in human HCC was strongly downregulated compared to the normal liver tissues. In addition, pro-inflammatory cytokines were able to decrease FXR expression by inhibiting the FXR promoter activity. In conclusion this work demonstrates FXR expression is strongly downregulated in human HCC, which may be caused by decreased FXR promoter activity, suggesting a potential role of FXR in human HCC development.
基金supported by Medical Science and Technology Research Foundation of Guangdong Province(2015120104622949)
文摘OBJECTIVE Cervical cancer is the third most malignant tumor in the world.Farnesoid X receptor(FXR) is a member of nuclear receptor superfamily.It is highly expressed in liver,kidney and small intestine,while it showed low expression level in other tissues.It not only plays an important role in the metabolism of bile acids and sugars,but also in the production of chronic inflammation in the early stage of cancer,the proliferation and migration of tumor.Compared with the normal tissue,the expression of FXR in most tumor tissues decreased.But there is no correlation between cervical cancer and FXR.So we aimed to find out the relationship between FXR and cervical cancer.METHODS A clinical study using q PCR,western blot and immunohistochemistry detected the expression of FXR in tumor tissues and normal tissues of clinical patients.FXR was activated by agonists or over-expressed by lentivirus.MTT,clone formation and flow cytometry were used to detect the relationship between FXR and proliferation of cervical cell lines.Tumor growth ability of FXR was detected by nude mice tumorigenicity.The interaction between FXR and CDKN2A-p14^(ARF)-MDM2-p53 pathway was detected by q PCR,Western blot and immunohistochemistry.RESULTS FXR was decreased in cancer tissues compared to normal control.Activation of FXR by agonist or constitutively-over-expression of FXR inhibited cervical cell proliferation.Over-expressed FXR attenuated Caski,Hela and Siha xenograft tumor growth in nude mice compared with control.Over-expression of FXR caused G1 cell-cycle arresting and up-regulated CDKN2A-p14^(ARF)-MDM2-p53 pathway.CONCLUSION FXR inhibits cervical cancer cell proliferation and cervical tumorigenicity which is related to CDKN2A-p14^(ARF)-MDM2-p53 pathway.Activation or overexpression of FXR may be a potential target for the treatment of cervical cancer.
