Bile acids inhibit ferroptosis sensitivity through activating farnesoid X receptor in gastric cancer cells

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.

Bile-acid-activated farnesoid X receptor regulates hydrogen sulfide production and hepatic microcirculation

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.

GW4064, a farnesoid X receptor agonist, upregulates adipokine expression in preadipocytes and HepG2 cells

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.

Recent insights into farnesoid X receptor in non-alcoholic fatty liver disease

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.

A Cell-based High-throughput Screening Assay for Farnesoid X Receptor Agonists

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.

Pravastatin activates the expression of farnesoid X receptor and liver X receptor alpha in Hep3B cells

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.

Duodenal-jejunal bypass reduces serum ceramides via inhibiting intestinal bile acid-farnesoid X receptor pathway

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.

Farnesoid X receptor expression is reduced in human hepatocellular carcinoma

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.

Inhibition of cervical cancer cell proliferation and cervical tumorigenicity caused by farnesoid X receptor activation or over-expression is related to CDKN2A-p14^(ARF)-MDM2-p53 pathway

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.

Mechanism of FXR alleviating the liver fibrosis by regulating perilipin 5

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.

A combined nanotherapeutic approach targeting farnesoid X receptor,ferroptosis,and fibrosis for nonalcoholic steatohepatitis treatment

Obeticholic acid(OCA),a farnesoid X receptor(FXR)agonist with favorable effects on fatty and glucose metabolism,has been considered the leading candidate drug for nonalcoholic steatohepatitis(NASH)treatment.However,its limited effectiveness in resolving liver fibrosis and lipotoxicity-induced cell death remains a major drawback.Ferroptosis,a newly recognized form of cell death characterized by uncontrolled lipid peroxidation,is involved in the progression of NASH.Nitric oxide(NO)is a versatile biological molecule that can degrade extracellular matrix.In this study,we developed a PEGylated thiolated hollow mesoporous silica nanoparticles(MSN)loaded with OCA,as well as a ferroptosis inhibitor liproxsatin-1 and a NO donor S-nitrosothiol(ONL@MSN).Biochemical analyses,histology,multiplexed flow cytometry,bulk-tissue RNA sequencing,and fecal 16S ribosomal RNA sequencing were utilized to evaluate the effects of the combined nanoparticle(ONL@MSN)in a mouse NASH model.Compared with the OCA-loaded nanoparticles(O@MSN),ONL@MSN not only protected against hepatic steatosis but also greatly ameliorated fibrosis and ferroptosis.ONL@MSN also displayed enhanced therapeutic actions on the maintenance of intrahepatic macrophages/monocytes homeostasis,inhibition of immune response/lipid peroxidation,and correction of microbiota dysbiosis.These findings present a promising synergistic nanotherapeutic strategy for the treatment of NASH by simultaneously targeting FXR,ferroptosis,and fibrosis.

Saikosaponin D improves nonalcoholic fatty liver disease via gut microbiota-bile acid metabolism pathway

Non-alcoholic fatty liver disease(NAFLD)is the main cause of chronic liver disease worldwide.Bupleurum is widely used in the treatment of non-alcoholic fatty liver,and saikosaponin D(SSD)is one of the main active components of Bupleurum.The purpose of this study was to investigate the efficacy of SSD in the treatment of NAFLD and to explore the mechanism of SSD in the improvement of NAFLD based on“gut-liver axis”.Our results showed that SSD dose-dependently alleviated high fat diet-induced weight gain in mice,improved insulin sensitivity,and also reduced liver lipid accumulation and injury-related biomarkers aspartate aminotransferase(AST)and alanine aminotransferase(ALT).Further exploration found that SSD inhibited the mRNA expression levels of farnesoid X receptor(Fxr),small heterodimer partner(Shp),recombinant fibroblast growth factor 15(Fgf15)and apical sodium dependent bile acid transporter(Asbt)in the intestine,suggesting that SSD improved liver lipid metabolism by inhibiting intestinal FXR signaling.SSD can significantly reduce the gut microbiota associated with bile salt hydrolase(BSH)expression,such as Clostridium.Decreased BSH expression reduced the ratio of unconjugated to conjugated bile acids,thereby inhibiting the intestinal FXR.These data demonstrated that SSD ameliorated NAFLD potentially through the gut microbiota-bile acidintestinal FXR pathway and suggested that SSD is a promising therapeutic agent for the treatment of NAFLD.

Team players in the pathogenesis of metabolic dysfunctionsassociated steatotic liver disease:The basis of development of pharmacotherapy

Nutrient metabolism is regulated by several factors.Social determinants of health with or without genetics are the primary regulator of metabolism,and an unhealthy lifestyle affects all modulators and mediators,leading to the adaptation and finally to the exhaustion of cellular functions.Hepatic steatosis is defined by presence of fat in more than 5%of hepatocytes.In hepatocytes,fat is stored as triglycerides in lipid droplet.Hepatic steatosis results from a combination of multiple intracellular processes.In a healthy individual nutrient metabolism is regulated at several steps.It ranges from the selection of nutrients in a grocery store to the last step of consumption of ATP as an energy or as a building block of a cell as structural component.Several hormones,peptides,and genes have been described that participate in nutrient metabolism.Several enzymes participate in each nutrient metabolism as described above from ingestion to generation of ATP.As of now several publications have revealed very intricate regulation of nutrient metabolism,where most of the regulatory factors are tied to each other bidirectionally,making it difficult to comprehend chronological sequence of events.Insulin hormone is the primary regulator of all nutrients’metabolism both in prandial and fasting states.Insulin exerts its effects directly and indirectly on enzymes involved in the three main cellular function processes;metabolic,inflammation and repair,and cell growth and regeneration.Final regulators that control the enzymatic functions through stimulation or suppression of a cell are nuclear receptors in especially farnesoid X receptor and peroxisome proliferator-activated receptor/RXR ligands,adiponectin,leptin,and adiponutrin.Insulin hormone has direct effect on these final modulators.Whereas blood glucose level,serum lipids,incretin hormones,bile acids in conjunction with microbiota are intermediary modulators which are controlled by lifestyle.The purpose of this review is to overview the key players in the pathogenesis of metabolic dysfunction-associated steatotic liver disease(MASLD)that help us understand the disease natural course,risk stratification,role of lifestyle and pharmacotherapy in each individual patient with MASLD to achieve personalized care and target the practice of precision medicine.PubMed and Google Scholar databases were used to identify publication related to metabolism of carbohydrate and fat in states of health and disease states;MASLD,cardiovascular disease and cancer.More than 1000 publications including original research and review papers were reviewed.

FXR agonist GW4064 alleviates endotoxin-induced hepatic inflammation by repressing macrophage activation

AIM: To examine the effect of farnesoid X receptor (FXR) activation by GW4064 on endotoxin-induced hepatic inflammation in nonalcoholic fatty liver disease (NAFLD) and the underlying mechanism.

Reduction in Bile Acid Pool Causes Delayed Liver Regeneration Accompanied by Down-regulated Expression of FXR and C-Jun mRNA in Rats

The present study attempted to examine the effects of bile acid pool size on liver regeneration after hepatectomy.The rats were fed on 0.2% cholic acid(CA)or 2% cholestyramine for 7 days to induce a change in the bile acid size,and then a partial hepatectomy(PH)was performed.Rats fed on the normal diet served as the controls.Measurements were made on the rate of liver regeneration,the labeling indices of PCNA,the plasma total bile acids(TBA),and the mRNA expression of cholesterol 7alpha-hydroxylase(CYP7A1),...

Bile acid increases expression of the histamine-producing enzyme,histidine decarboxylase,in gastric cells

AIM: To investigate the effect of bile acid on the expression of histidine decarboxylase (HDC), which is a major enzyme involved in histamine production, and gene expression of gastric transcription factors upon cooperative activation.

Moxibustion improves experimental colitis in rats with Crohn's disease by regulating bile acid enterohepatic circulation and intestinal farnesoid X receptor

Objective:This study was conducted to explore the mechanism of intestinal inflammation and barrier repair in Crohn’s disease(CD)regulated by moxibustion through bile acid(BA)enterohepatic circulation and intestinal farnesoid X receptor(FXR).Methods:Sprague-Dawley rats were randomly divided into control group,CD model group,mild moxibustion group and herb-partitioned moxibustion group.CD model rats induced by 2,4,6-trinitrobenzene sulfonic acid were treated with mild moxibustion or herb-partitioned moxibustion at Tianshu(ST25)and Qihai(CV6).The changes in CD symptoms were rated according to the disease activity index score,the serum and colon tissues of rats were collected,and the pathological changes in colon tissues were observed via histopathology.Western blot,immunohistochemistry(IHC)and immunofluorescence were used to evaluate the improvement of moxibustion on intestinal inflammation and mucosal barrier in CD by the BA-FXR pathway.Results:Mild moxibustion and herb-partitioned moxibustion improved the symptoms of CD,inhibited inflammation and repaired mucosal damage to the colon in CD rats.Meanwhile,moxibustion could improve the abnormal expression of BA in the colon,liver and serum,downregulate the expression of interferon-γand upregulate the expression of FXR mRNA,and inhibit Toll-like receptor 4(TLR4)and myeloid differentiation factor 88(MyD88)mRNA.The IHC results showed that moxibustion could upregulate the expression of FXR and mucin2 and inhibit TLR4 expression.Western blot showed that moxibustion inhibited the protein expression of TLR4 and MyD88 and upregulated the expression of FXR.Immunofluorescence image analysis showed that moxibustion increased the colocalization sites and intensity of FXR with TLR4 or nuclear factor-κB p65.In particular,herb-partitioned moxibustion has more advantages in improving BA and upregulating FXR and TLR4 in the colon.Conclusion:Mild moxibustion and herb-partitioned moxibustion can improve CD by regulating the enterohepatic circulation stability of BA,activating colonic FXR,regulating the TLR4/MyD88 pathway,inhibiting intestinal inflammation and repairing the intestinal mucosal barrier.Herb-partitioned moxibustion seems to have more advantages in regulating BA enterohepatic circulation and FXR activation.Please cite this article as:Shen JC,Qi Q,Han D,Lu Y,Huang R,Zhu Y,Zhang LS,Qin XD,Zhang F,Wu HG,Liu HR.Moxibustion improves experimental colitis in rats with Crohn’s disease by regulating bile acid enterohepatic circulation and intestinal farnesoid X receptor.J Integr Med.2023;21(2):194–204.

Bile duct ligation differently regulates protein expressions of organic cation transporters in intestine,liver and kidney of rats through activation of farnesoid X receptor by cholate and bilirubin

Body is equipped with organic cation transporters(OCTs).These OCTs mediate drug transport and are also involved in some disease process.We aimed to investigate whether liver failure alters intestinal,hepatic and renal Oct expressions using bile duct ligation(BDL)rats.Pharmacokinetic analysis demonstrates that BDL decreases plasma metformin exposure,associated with decreased intestinal absorption and increased urinary excretion.Western blot shows that BDL significantly downregulates intestinal Oct2 and hepatic Oct1 but upregulates renal and hepatic Oct2.In vitro cell experiments show that chenodeoxycholic acid(CDCA),bilirubin and farnesoid X receptor(FXR)agonist GW4064 increase OCT2/Oct2 but decrease OCT1/Oct1,which are remarkably attenuated by glycine-β-muricholic acid and silencing FXR.Significantly lowered intestinal CDCA and increased plasma bilirubin levels contribute to different Octs regulation by BDL,which are confirmed using CDCA-treated and bilirubin-treated rats.A disease-based physiologically based pharmacokinetic model characterizing intestinal,hepatic and renal Octs was successfully developed to predict metformin pharmacokinetics in rats.In conclusion,BDL remarkably downregulates expressions of intestinal Oct2 and hepatic Oct1 protein while upregulates expressions of renal and hepatic Oct2 protein in rats,finally,decreasing plasma exposure and impairing hypoglycemic effects of metformin.BDL differently regulates Oct expressions via Fxr activation by CDCA and bilirubin.

Farnesoid X receptor regulators from natural products and their biological function

Metabolic syndrome(Met S)has been a growing public health concern worldwide without specific medicine.Through summarizing the chemical structure type and effect mechanisms of natural products targeted on farnesoid X receptor(FXR),to provide the research basis for exploring the treatment of Met S.The following databases were searched for natural products which targeting FXR:Pub Med,Embase,the Cochrane Library,Web of Science,China National Knowledge Infrastructure Database,Wanfang Database,China Science and Technology Journal Database,and Chinese Biomedical Literature Database.Totally 120 natural products were summarized,including terpenoids(51 compounds),steroidal saponins(27 compounds),phenylpropanolds(19 compounds),flavonoids(13 compounds),alkaloids(3 compounds)and others(7 compounds),most researches focus on terpenoids and part of synthetic FXR regulators were based on the structure of terpenoids.FXR regulators could improve cholestasis and liver injury,hyperlipidemia,diabetes and atherosclerosis.FXR is a potential target of treating Met S.Natural products are characteristics with unique novel structures and special biological activity,and they are important sources of bioactive precursor compounds and drug discovery.Exploring the effects and mechanism of natural products and its derivative on Met S by targeting FXR may be a new way to develop the new drugs of treating Met S.

In vivo mouse models to study bile acid synthesis and signaling

The synthesis of bile acids(BAs)is carried out by complex pathways characterized by sequential chemical reactions in the liver through various cytochromes P450(CYP)and other enzymes.Maintaining the integrity of these pathways is crucial for normal physiological function in mammals,encompassing hepatic and neurological processes.Studying on the deficiencies in BA synthesis genes offers valuable insights into the significance of BAs in modulating farnesoid X receptor(FXR)signaling and metabolic homeostasis.By creating mouse knockout(KO)models,researchers can manipulate deficiencies in genes involved in BA synthesis,which can be used to study human diseases with BA dysregulation.These KO mouse models allow for a more profound understanding of the functions and regulations of genes responsible for BA synthesis.Furthermore,KO mouse models shed light on the distinct characteristics of individual BA and their roles in nuclear receptor signaling.Notably,alterations of BA synthesis genes in mouse models have distinct differences when compared to human diseases caused by the same BA synthesis gene deficiencies.This review summarizes several mouse KO models used to study BA synthesis and related human diseases,including mice deficient in Cyp7a1,Cyp27a1,Cyp7a1/Cyp27a1,Cyp8b1,Cyp7b1,Cyp2c70,Cyp2a12,and Cyp2c70/Cyp2a12,as well as germ-free mice.