AIM To ascertain whether cholestasis affects the expression of two CYP3 A isoforms(CYP3 A1 and CYP3 A2) and of pregnane X receptor(PXR) and constitutive androstane receptor(CAR).METHODS Cholestasis was induced by bile...AIM To ascertain whether cholestasis affects the expression of two CYP3 A isoforms(CYP3 A1 and CYP3 A2) and of pregnane X receptor(PXR) and constitutive androstane receptor(CAR).METHODS Cholestasis was induced by bile duct ligation in 16 male Wistar rats; whereas 8 sham-operated rats were used as controls. Severity of cholestasis was assessed on histological examination of liver sections, and serum concentrations of albumin, AST, ALT, GGT, ALPK and bilirubin. Gene and protein expressions of PXR, CAR, CYP3 A1 and CYP3 A2 were assessed by means of q RT-PCR and Western blot, respectively. Alterations in CYP3 A activity were measured by calculating the kinetic parameters of 4-OH and 1'-OH-midazolam hydroxylation, marker reactions for CYP3 A enzymes.RESULTS The m RNA and protein expression of CYP3 A1 increased significantly in mild cholestasis(P < 0.01). At variance, m RNA and protein expression of CYP3 A2 didn't change in mild cholestasis, whereas the expression and activity of both CYP3 A1 and CYP3 A2 decreased dramatically when cholestasis became severe. Consistently with these observations, the nuclear expression of both PXR and CAR, which was measured because they both translocate into the cell nucleus after their activation, virtually disappeared in the late stage of cholestatic injury, after an initial increase. These results indicate that early-and late-stage cholestasis affects CYP3 Amediated drug metabolism differently, probably as consequence of the different activation of PXR and CAR.CONCLUSION Early-and late-stage cholestasis affects CYP3 Amediated drug metabolism differently. PXR and CAR might be targeted therapeutically to promote CYP3 Amediated liver detoxification.展开更多
Bacterial translocation(BT) has been impeccably implicated as a driving factor in the pathogenesis of a spectrum of chronic liver diseases(CLD). Scientific evidence accumulated over the last four decades has implied t...Bacterial translocation(BT) has been impeccably implicated as a driving factor in the pathogenesis of a spectrum of chronic liver diseases(CLD). Scientific evidence accumulated over the last four decades has implied that the disease pathologies in CLD and BT are connected as a loop in the gut-liver axis and exacerbate each other. Pregnane X receptor(PXR) is a ligandactivated transcription factor and nuclear receptor that is expressed ubiquitously along the gut-liver-axis. PXR has been intricately associated with the regulation of various mechanisms attributed in causing BT. The importance of PXR as the mechanistic linker molecule in the gutliver axis and its role in regulating bacterial interactions with the host in CLD has not been explored. Pub Med was used to perform an extensive literature search using the keywords PXR and bacterial translocation, PXR and chronic liver disease including cirrhosis. In an adequate expression state, PXR acts as a sensor for bile acid dysregulation and bacterial derived metabolites, and in response shapes the immune profile beneficial to the host. Activation of PXR could be therapeutic in CLD as it counter-regulates endotoxin mediated inflammation and maintains the integrity of intestinal epithelium. This review mainly focuses PXR function and its regulation in BT in the context of chronic liver diseases.展开更多
The whole plants of Ypsilandra thibetica have been analyzed as part of a systematic study on saponin constituents of medicinal plants.This has resulted in the isolation of two new bisdesmosidic furostanol saponins,nam...The whole plants of Ypsilandra thibetica have been analyzed as part of a systematic study on saponin constituents of medicinal plants.This has resulted in the isolation of two new bisdesmosidic furostanol saponins,named ypsilandroside P(1)and ypsilandroside Q(2),and one new pregnane glycoside,named ypsilandroside R(3),together with nine known steroidal glycosides.Their structures were elucidated on the basis of extensive spectroscopic analysis,including that of 2D NMR data,and the results of acidic hydrolysis.Ypsilandroside P(1)was cytotoxicity against two human tumor cell lines.展开更多
A novel pregnane glycoside, biondianoside E, was isolated from the roots of Biondia chinensis. By the spectroscopic and chemical methods, this structure was elucidated as 3B, 5B, 14B, 205, 21-pentahydroxypregnane 3-O-...A novel pregnane glycoside, biondianoside E, was isolated from the roots of Biondia chinensis. By the spectroscopic and chemical methods, this structure was elucidated as 3B, 5B, 14B, 205, 21-pentahydroxypregnane 3-O-B-D-glucopyranosyl-(1-4)-B-D-cymaropyranoside .展开更多
A new minor pregnane glycoside was isolated from the fermented leaves of Agave americana. Its structure was elucidated as (20S)-5a-pregnane-3? 20-diol 20-O--D-glucopyrano- side (1) by spectral methods.
Pregnane and Xenobiotic Receptor (PXR; or Steroid and Xenobiotic Receptor, SXR), a new member of the nuclear receptor superfamily, is thought to modulate a network of genes that are involved in xenobiotic metabolism a...Pregnane and Xenobiotic Receptor (PXR; or Steroid and Xenobiotic Receptor, SXR), a new member of the nuclear receptor superfamily, is thought to modulate a network of genes that are involved in xenobiotic metabolism and elimination. To further explore the role of PXR in body’s homeostatic mechanisms, we for the first time, report successful prokary- otic expression and purification of full-length PXR and preparation of polyclonal antibody against the whole protein. The full-length cDNA encoding a 434 amino acids protein was sub-cloned into prokaryotic expression vector, pET-30b and transformed into E. coli BL21(DE3) cells for efficient over expression. The inclusion body fraction, containing the expressed recombinant protein, was purified first by solubilizing in sarcosine extraction buffer and then by affinity column chromatography using Ni-NTA His-Bind matrix. The efficacy of anti-PXR antibody was confirmed by immunocytology, Western blot analysis, EMSA and immunohistochemistry. The antibody obtained was capable of detecting human and mouse PXR with high specificity and sensitivity. Immunofluorescence staining of COS-1 cells transfected with human or mouse PXR showed a clear nuclear localization. Results from immunohistochemistry showed that level of PXR in liver sections is immunologically detectable in the nuclei. Similar to exogenously transfected PXR, Western blot analysis of cell extract from HepG2 and COLO320DM cells revealed a major protein band for endogenous PXR having the expected molecular weight of 50 kDa. Relevance of other immunodetectable bands with reference to PXR isoforms and current testimony are evaluated. Advantages of antibody raised against full-length PXR protein for functional characterization of receptor is discussed and its application for clinical purposes is envisaged.展开更多
Breast cancer is the most common malignancy in women worldwide.Triplenegative breast cancer(TNBC),refers breast cancer negative for estrogen receptor,progesterone receptor and human epidermal growth factor receptor 2,...Breast cancer is the most common malignancy in women worldwide.Triplenegative breast cancer(TNBC),refers breast cancer negative for estrogen receptor,progesterone receptor and human epidermal growth factor receptor 2,characterized by high drug resistance,high metastasis and high recurrence,treatment of which is a difficult problem in the clinical treatment of breast cancer.In order to better treat TNBC clinically,it is a very urgent task to explore the mechanism of TNBC resistance in basic breast cancer research.Pregnane X receptor(PXR)is a nuclear receptor whose main biological function is to participate in the metabolism,transport and clearance of allobiological agents in PXR.PXR plays an important role in drug metabolism and clearance,and PXR is highly expressed in tumor tissues of TNBC patients,which is related to the prognosis of breast cancer patients.This reviews synthesized the important role of PXR in the process of high drug resistance to TNBC chemotherapeutic drugs and related research progress.展开更多
Human pregnane X receptor (PXR) is of vital importance in pharmaceutical and exogenous compound metabolism within the body. This provides strong motivation for investigating this orphan receptor’s activation by vario...Human pregnane X receptor (PXR) is of vital importance in pharmaceutical and exogenous compound metabolism within the body. This provides strong motivation for investigating this orphan receptor’s activation by various pharmaceuticals, xenobiotics, and endocrine disrupting chemicals (EDCs). A nanomechanical transducer is developed to study xenobiotic and EDC interactions with the bioreceptor PXR’s ligand binding domain (LBD). The combination of immobilized LBD PXR with a nanostructured microcantilever (MC) platform allows for the sensitive, label-free study of ligand interaction with the receptor. PXR shows real-time, reversible responses when exposed to a specific pharmaceutical, EDCs, and xenobiotic ligands. Three EDCs binding interactions are tested, which include phthalic acid, nonylphenol, and bisphenol A, with PXR. PXR LBD was exposed to rifampicin, a potent PXR activator, with various injection and recovery times to study their interaction. A two protein array of PXR and estrogen receptor ? (ER-?) directly compares the nanomechanical responses of these receptors with rifampicin on a single platform.展开更多
To search for pharmacologically active constituents of folk medicine, a new pregnane, 2α,3α,15β-trihydroxy-20（S）-tigloyl-pregnane （compound 1）, and nine known compounds, geranylgeraniol （compound 2）, β-dauco...To search for pharmacologically active constituents of folk medicine, a new pregnane, 2α,3α,15β-trihydroxy-20（S）-tigloyl-pregnane （compound 1）, and nine known compounds, geranylgeraniol （compound 2）, β-daucosterol （compound 3）, 6-hydroxystigmast-4oen-3-one （compound 4）, sitoindoside Ⅰ （compound 5）, sitoindoside Ⅱ （compound 6）, β-sitosterol （compound 7）, kaempferol （compound 8）, quercetin （compound 9）, and rutin （compound 10）, were isolated from the ethanol extract of whole plants of Munronia delavayi Franch using chromatographic methods. The structures of compounds 1-10 were elucidated on the basis of spectral data.展开更多
Objective To study the chemical constituents from the stems of Marsdenia tenacissima.Methods The chemical constituents were isolated by various column chromatography and their structures were identified by spectral an...Objective To study the chemical constituents from the stems of Marsdenia tenacissima.Methods The chemical constituents were isolated by various column chromatography and their structures were identified by spectral and chemical analysis.Results Two pregnane glycosides were isolated from the stems of M.tenacissima and identified as 3-O-β-D-glucopyranosyl-(1→4)-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α-O-tigloyltenacigenin B,named as tenacigenoside I(1)and 3-O-β-D-glucopyranosyl-(1→4)-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α,12β-di-O-acetyltenacigenin B,named as tenacigenoside K(2).Conclusion Compound 1 is a new compound,1H-NMR and 13C-NMR data of compound 2 are reported for the first time.展开更多
Pregnane X receptor(PXR)is the major regulator of xenobiotic metabolism.PXR itself is controlled by various signaling molecules including glucocorticoids.Moreover,negative feed-back regulation has been proposed at the...Pregnane X receptor(PXR)is the major regulator of xenobiotic metabolism.PXR itself is controlled by various signaling molecules including glucocorticoids.Moreover,negative feed-back regulation has been proposed at the transcriptional level.We examined the involvement of the 3’-untranslated region(3’-UTR)of NR1I2 mRNA and microRNAs in PXR-and glucocorticoid receptor(GR)-mediated regulation of NR1I2 gene expression.PXR ligands were found to significantly downregulate NR1I2 mRNA expression in a set of 14 human hepatocyte cultures.Similarly,PXR was downregulated by PCN in the C57/BL6 mice liver.In mechanistic studies with the full-length 3’-UTR cloned into luciferase reporter or expression vectors,we showed that the 3’-UTR reduces PXR expression.From the miRNAs tested,miR-18a-5p inhibited both NR 112 expression and CYP3A4 gene induction.Importantly,we observed significant upregulation of miR-18a-5p expression 6 h after treatment with the PXR ligand rifampicin,which indicates a putative mechanism underlying NR1I2 negative feed-back regulation in hepatic cells.Additionally,glucocorticoids upregulated NR1I2 expression not only through the promoter region but also via 3’-UTR regulation,which likely involves downregulation of miR-18a-5p.We conclude that miR-18a-5p is involved in the down-regulation of NR1I2expression by its ligands and in the upregulation of NR1I2 mRNA expression by glucocorticoids in hepatic cells.展开更多
During the last decade, much progress has been made in exploring the mechanisms of alterations elicited by foreign compounds in xeno- and endobiotic metabolism regulated by the human nuclear pregnane X receptor （PXR...During the last decade, much progress has been made in exploring the mechanisms of alterations elicited by foreign compounds in xeno- and endobiotic metabolism regulated by the human nuclear pregnane X receptor （PXR）. PXR, identified as a human nuclear receptor in 1998 and generally regarded as a sensor activated by exogenous and endogenous chemicals, regulates a large number of enzymes and transporters involved in the response of mammals to their chemical environment.展开更多
Alcoholic steatohepatitis (ASH) is a liver disease characterized by steatosis, inflammation, and necrosis of the liver tissue as a result of excessive alcohol consumption. Pregnane X receptor (PXR) is a xenobiotic nuc...Alcoholic steatohepatitis (ASH) is a liver disease characterized by steatosis, inflammation, and necrosis of the liver tissue as a result of excessive alcohol consumption. Pregnane X receptor (PXR) is a xenobiotic nuclear receptor best known for its function in the transcriptional regulation of drug metabolism and disposition. Clinical reports suggested that the antibiotic rifampicin, a potent human PXR activator, is a contraindication in alcoholics, but the mechanism was unclear. In this study, we showed that the hepatic expression of fatty acid binding protein 4 (FABP4) was uniquely elevated in ASH patients and a mouse model of ASH. Pharmacological inhibiting FABP4 attenuated ASH in mice. Furthermore, treatment of mice with the mouse PXR agonist pregnenolon-16α-carbonitrile (PCN) induced the hepatic and circulating levels of FABP4 and exacerbated ASH in a PXR-dependent manner. Our mechanism study established FABP4 as a transcriptional target of PXR. Treatment with andrographolide, a natural compound and dual inhibitor of PXR and FABP4, alleviated mice from ASH. In summary, our results showed that the PXR-FABP4 gene regulatory axis plays an important role in the progression of ASH, which may have accounted for the contraindication of rifampicin in patients of alcoholic liver disease. Pharmacological inhibition of PXR and/or FABP4 may have its promise in the clinical management of ASH.展开更多
Microbial transformation of pregnane-3β,16β,20-triol （1） by Cunninghamella echinulata afforded four previ- ously unreported polyhydroxylated steroids, namely pregnane-3β,14a,16β,20-tetrol （2）, pregnane-3-oxo-1...Microbial transformation of pregnane-3β,16β,20-triol （1） by Cunninghamella echinulata afforded four previ- ously unreported polyhydroxylated steroids, namely pregnane-3β,14a,16β,20-tetrol （2）, pregnane-3-oxo-14a, 16β,20-triol （3）, pregnane-3-oxo-7β,16β,20-triol （4）, and pregnane-3fl,7β,16β,20-tetrol （5）. The structures of these metabolites were established by means of spectroscopic analysis （1D and 2D NMR as well as HRESIMS analysis）.展开更多
Background and aims:The herbal supplement Gancao,also known as licorice,belongs to the genus Glycyrrhiza and has been used worldwide for its hepatoprotective effect.Recent studies have raised concerns about potential ...Background and aims:The herbal supplement Gancao,also known as licorice,belongs to the genus Glycyrrhiza and has been used worldwide for its hepatoprotective effect.Recent studies have raised concerns about potential herb-drug interactions associated with Gancao via pregnane X receptor(PXR)-mediated induction of hepatic cytochrome P4503A4(CYP3A4).The current work aimed to determine the phytochemicals in Gancao that activate PXR and induce CYP3A4.Methods:DPX2 cells were used for cell-based PXR reporter assays.The phytochemicals in Gancao extract were identified using a metabolomics approach.The effects of PXR activators identified from in vitro studies were further investigated in PXR-and CYP3A4-humanized mouse models.Results:Gancao was verified to be a PXR-activating herb.Two major phytochemicals in Gancao,gly-cyrrhizin(GZ)and glycyrrhetinic acid(GA),did not activate PXR in the cell-based reporter assays.However,glabridin was shown to activate PXR in a dose-dependent manner.In vivo studies confirmed that GZ is not a PXR activator and glabridin is a weak PXR activator.Although GA did not active PXR in vitro,it induced CYP3A4 expression in a PXR-dependent manner in the PXR-and CYP3A4-humanized mice.展开更多
The pregnane X receptor(PXR)is a ligand activated nuclear receptor that is highly expressed in the liver and regulates many cellular functions including drug metabolism,endobiotic metabolism,oxidative stress response,...The pregnane X receptor(PXR)is a ligand activated nuclear receptor that is highly expressed in the liver and regulates many cellular functions including drug metabolism,endobiotic metabolism,oxidative stress response,apoptosis,inflammation,cell proliferation and regeneration.PXR activation promotes drug-induced liver injury(DILI)through its ability to increase the expression of phaseⅠand phaseⅡdrug metabolizing enzymes.The PXR also increases lipid synthesis and fatty acid uptake into the liver,leading to lipid accumulation and steatosis.In recent years,PXR has been explored as an important target in DILI and liver diseases.This review will highlight the roles of PXR in modulating DILI.PXR polymorphisms that have been associated with DILI will also be discussed.展开更多
Background and Aims:Hepatitis B virus(HBV)infection has been found to increase hepatocellular sensitivity to carcinogenic xenobiotics,by unknown mechanisms,in the generation of hepatocellular carcinoma.The pregnane X ...Background and Aims:Hepatitis B virus(HBV)infection has been found to increase hepatocellular sensitivity to carcinogenic xenobiotics,by unknown mechanisms,in the generation of hepatocellular carcinoma.The pregnane X receptor(PXR)is a key regulator of the body’s defense against xenobiotics,including xenobiotic carcinogens and clinical drugs.In this study,we aimed to investigate the molecular mechanisms of HBV X protein(HBx)-PXR signaling in the synergistic effects of chemical carcinogens in HBV-associated hepatocarcinogenesis.Methods:The expression profile of PXR-cytochrome p4503A4(CYP3A4)signaling was determined by PCR,western blotting,and tissue microarray.Cell viability and aflatoxin B1(AFB1)cytotoxicity were measured using the cell counting kit-8 assay.Target gene expression was evaluated using transient transfection and real time-PCR.The genotoxicity of AFB1 was assessed in newborn mice with a single dose of AFB1.Results:HBx enhanced the hepatotoxicity of AFB1 by activating CYP3A4 and reducing glutathione Stransferase Mu 1(GSTM1)in cell lines.Activation of PXR by pregnenolone 16α-carbonitrile increased AFB1-induced liver tumor incidence by up-regulating oncogenic KRAS to enhance interleukin(IL)-11:IL-11 receptor subunit alpha-1(IL11RA-1)-mediated inflammation in an HBx transgenic model.Conclusions:Our finding regarding AFB1 toxicity enhancement by an HBx-PXR-CYP3A4/GSTM1-KRASIL11:IL11RA signaling axis provides a rational explanation for the synergistic effects of chemical carcinogens in HBV infection-associated hepatocarcinogenesis.展开更多
利托那韦(ritonavir,RTV)作为抗病毒药物广泛应用于临床,但其肝毒性机制尚未完全阐明。本研究旨在探讨孕烷X受体(pregnane X receptor,PXR)激活促进RTV肝毒性的分子机制。本实验获得郑州大学生命科学伦理审查委员会批准(批准号:ZZUIRB20...利托那韦(ritonavir,RTV)作为抗病毒药物广泛应用于临床,但其肝毒性机制尚未完全阐明。本研究旨在探讨孕烷X受体(pregnane X receptor,PXR)激活促进RTV肝毒性的分子机制。本实验获得郑州大学生命科学伦理审查委员会批准(批准号:ZZUIRB2022-142)。构建Pxr基因敲除小鼠,给予PXR激动剂和RTV处理,检测肝功能指标、代谢酶、内质网(endoplasmic reticulum,ER)应激和细胞凋亡相关基因的表达及RTV主要活性代谢产物,并在细胞水平进行验证。结果显示,PXR激活加剧RTV所致小鼠肝损伤,伴随相关代谢酶上调、RTV活性代谢产物积累、ER应激、细胞死亡及组织损伤相关分子表达上调;在HepG2细胞中,过表达PXR联合利福平使RTV肝细胞毒性增加,而敲低细胞色素P450酶(cytochrome P450,CYP) 3A4后毒性得以逆转。机制上,PXR激活通过上调CYP3A4加速RTV代谢为毒性产物,后者触发ER应激,促进肝细胞毒性。本研究揭示了PXR-CYP3A4轴通过触发ER应激在RTV肝毒性中的核心作用,为靶向调控PXR以减轻药物性肝损伤提供新策略。展开更多
基金Supported by the University of Padova,No.CPDA138721/13
文摘AIM To ascertain whether cholestasis affects the expression of two CYP3 A isoforms(CYP3 A1 and CYP3 A2) and of pregnane X receptor(PXR) and constitutive androstane receptor(CAR).METHODS Cholestasis was induced by bile duct ligation in 16 male Wistar rats; whereas 8 sham-operated rats were used as controls. Severity of cholestasis was assessed on histological examination of liver sections, and serum concentrations of albumin, AST, ALT, GGT, ALPK and bilirubin. Gene and protein expressions of PXR, CAR, CYP3 A1 and CYP3 A2 were assessed by means of q RT-PCR and Western blot, respectively. Alterations in CYP3 A activity were measured by calculating the kinetic parameters of 4-OH and 1'-OH-midazolam hydroxylation, marker reactions for CYP3 A enzymes.RESULTS The m RNA and protein expression of CYP3 A1 increased significantly in mild cholestasis(P < 0.01). At variance, m RNA and protein expression of CYP3 A2 didn't change in mild cholestasis, whereas the expression and activity of both CYP3 A1 and CYP3 A2 decreased dramatically when cholestasis became severe. Consistently with these observations, the nuclear expression of both PXR and CAR, which was measured because they both translocate into the cell nucleus after their activation, virtually disappeared in the late stage of cholestatic injury, after an initial increase. These results indicate that early-and late-stage cholestasis affects CYP3 Amediated drug metabolism differently, probably as consequence of the different activation of PXR and CAR.CONCLUSION Early-and late-stage cholestasis affects CYP3 Amediated drug metabolism differently. PXR and CAR might be targeted therapeutically to promote CYP3 Amediated liver detoxification.
文摘Bacterial translocation(BT) has been impeccably implicated as a driving factor in the pathogenesis of a spectrum of chronic liver diseases(CLD). Scientific evidence accumulated over the last four decades has implied that the disease pathologies in CLD and BT are connected as a loop in the gut-liver axis and exacerbate each other. Pregnane X receptor(PXR) is a ligandactivated transcription factor and nuclear receptor that is expressed ubiquitously along the gut-liver-axis. PXR has been intricately associated with the regulation of various mechanisms attributed in causing BT. The importance of PXR as the mechanistic linker molecule in the gutliver axis and its role in regulating bacterial interactions with the host in CLD has not been explored. Pub Med was used to perform an extensive literature search using the keywords PXR and bacterial translocation, PXR and chronic liver disease including cirrhosis. In an adequate expression state, PXR acts as a sensor for bile acid dysregulation and bacterial derived metabolites, and in response shapes the immune profile beneficial to the host. Activation of PXR could be therapeutic in CLD as it counter-regulates endotoxin mediated inflammation and maintains the integrity of intestinal epithelium. This review mainly focuses PXR function and its regulation in BT in the context of chronic liver diseases.
基金supported by National Natural Science Funding of China(No.31170333)the Natural Sci-ence Foundation of Yunnan Province(No.2009CC019)+1 种基金the West Light Foundation of the Chinese Academy of Sciences(No.2908025712W1)a fund(No.540806321211)of State Key Laboratory of Phytochemistry and Plant Resources in West China,Germplasm Bank of Wild Species and CAS Innovation Program of Kunming Institute of Botany.
文摘The whole plants of Ypsilandra thibetica have been analyzed as part of a systematic study on saponin constituents of medicinal plants.This has resulted in the isolation of two new bisdesmosidic furostanol saponins,named ypsilandroside P(1)and ypsilandroside Q(2),and one new pregnane glycoside,named ypsilandroside R(3),together with nine known steroidal glycosides.Their structures were elucidated on the basis of extensive spectroscopic analysis,including that of 2D NMR data,and the results of acidic hydrolysis.Ypsilandroside P(1)was cytotoxicity against two human tumor cell lines.
文摘A novel pregnane glycoside, biondianoside E, was isolated from the roots of Biondia chinensis. By the spectroscopic and chemical methods, this structure was elucidated as 3B, 5B, 14B, 205, 21-pentahydroxypregnane 3-O-B-D-glucopyranosyl-(1-4)-B-D-cymaropyranoside .
基金supported by the National Natulal Science Foundation of China(NSFC)(39969005).
文摘A new minor pregnane glycoside was isolated from the fermented leaves of Agave americana. Its structure was elucidated as (20S)-5a-pregnane-3? 20-diol 20-O--D-glucopyrano- side (1) by spectral methods.
文摘Pregnane and Xenobiotic Receptor (PXR; or Steroid and Xenobiotic Receptor, SXR), a new member of the nuclear receptor superfamily, is thought to modulate a network of genes that are involved in xenobiotic metabolism and elimination. To further explore the role of PXR in body’s homeostatic mechanisms, we for the first time, report successful prokary- otic expression and purification of full-length PXR and preparation of polyclonal antibody against the whole protein. The full-length cDNA encoding a 434 amino acids protein was sub-cloned into prokaryotic expression vector, pET-30b and transformed into E. coli BL21(DE3) cells for efficient over expression. The inclusion body fraction, containing the expressed recombinant protein, was purified first by solubilizing in sarcosine extraction buffer and then by affinity column chromatography using Ni-NTA His-Bind matrix. The efficacy of anti-PXR antibody was confirmed by immunocytology, Western blot analysis, EMSA and immunohistochemistry. The antibody obtained was capable of detecting human and mouse PXR with high specificity and sensitivity. Immunofluorescence staining of COS-1 cells transfected with human or mouse PXR showed a clear nuclear localization. Results from immunohistochemistry showed that level of PXR in liver sections is immunologically detectable in the nuclei. Similar to exogenously transfected PXR, Western blot analysis of cell extract from HepG2 and COLO320DM cells revealed a major protein band for endogenous PXR having the expected molecular weight of 50 kDa. Relevance of other immunodetectable bands with reference to PXR isoforms and current testimony are evaluated. Advantages of antibody raised against full-length PXR protein for functional characterization of receptor is discussed and its application for clinical purposes is envisaged.
基金Supported by Science project of Hunan Provincial Health Commission,No.B202304089304.
文摘Breast cancer is the most common malignancy in women worldwide.Triplenegative breast cancer(TNBC),refers breast cancer negative for estrogen receptor,progesterone receptor and human epidermal growth factor receptor 2,characterized by high drug resistance,high metastasis and high recurrence,treatment of which is a difficult problem in the clinical treatment of breast cancer.In order to better treat TNBC clinically,it is a very urgent task to explore the mechanism of TNBC resistance in basic breast cancer research.Pregnane X receptor(PXR)is a nuclear receptor whose main biological function is to participate in the metabolism,transport and clearance of allobiological agents in PXR.PXR plays an important role in drug metabolism and clearance,and PXR is highly expressed in tumor tissues of TNBC patients,which is related to the prognosis of breast cancer patients.This reviews synthesized the important role of PXR in the process of high drug resistance to TNBC chemotherapeutic drugs and related research progress.
文摘Human pregnane X receptor (PXR) is of vital importance in pharmaceutical and exogenous compound metabolism within the body. This provides strong motivation for investigating this orphan receptor’s activation by various pharmaceuticals, xenobiotics, and endocrine disrupting chemicals (EDCs). A nanomechanical transducer is developed to study xenobiotic and EDC interactions with the bioreceptor PXR’s ligand binding domain (LBD). The combination of immobilized LBD PXR with a nanostructured microcantilever (MC) platform allows for the sensitive, label-free study of ligand interaction with the receptor. PXR shows real-time, reversible responses when exposed to a specific pharmaceutical, EDCs, and xenobiotic ligands. Three EDCs binding interactions are tested, which include phthalic acid, nonylphenol, and bisphenol A, with PXR. PXR LBD was exposed to rifampicin, a potent PXR activator, with various injection and recovery times to study their interaction. A two protein array of PXR and estrogen receptor ? (ER-?) directly compares the nanomechanical responses of these receptors with rifampicin on a single platform.
文摘To search for pharmacologically active constituents of folk medicine, a new pregnane, 2α,3α,15β-trihydroxy-20（S）-tigloyl-pregnane （compound 1）, and nine known compounds, geranylgeraniol （compound 2）, β-daucosterol （compound 3）, 6-hydroxystigmast-4oen-3-one （compound 4）, sitoindoside Ⅰ （compound 5）, sitoindoside Ⅱ （compound 6）, β-sitosterol （compound 7）, kaempferol （compound 8）, quercetin （compound 9）, and rutin （compound 10）, were isolated from the ethanol extract of whole plants of Munronia delavayi Franch using chromatographic methods. The structures of compounds 1-10 were elucidated on the basis of spectral data.
基金Foundation of Doctors of Southwest University for Nationalities(26701001)
文摘Objective To study the chemical constituents from the stems of Marsdenia tenacissima.Methods The chemical constituents were isolated by various column chromatography and their structures were identified by spectral and chemical analysis.Results Two pregnane glycosides were isolated from the stems of M.tenacissima and identified as 3-O-β-D-glucopyranosyl-(1→4)-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α-O-tigloyltenacigenin B,named as tenacigenoside I(1)and 3-O-β-D-glucopyranosyl-(1→4)-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α,12β-di-O-acetyltenacigenin B,named as tenacigenoside K(2).Conclusion Compound 1 is a new compound,1H-NMR and 13C-NMR data of compound 2 are reported for the first time.
基金supported by grants from the Czech Science Foundation 17-06841S to Petr PavekEFSA-CDN(No.CZ.02.1.01/0.0/0.0/16_019/0000841,Czech Republic)co-funded by ERDF to Tomas Smutny.
文摘Pregnane X receptor(PXR)is the major regulator of xenobiotic metabolism.PXR itself is controlled by various signaling molecules including glucocorticoids.Moreover,negative feed-back regulation has been proposed at the transcriptional level.We examined the involvement of the 3’-untranslated region(3’-UTR)of NR1I2 mRNA and microRNAs in PXR-and glucocorticoid receptor(GR)-mediated regulation of NR1I2 gene expression.PXR ligands were found to significantly downregulate NR1I2 mRNA expression in a set of 14 human hepatocyte cultures.Similarly,PXR was downregulated by PCN in the C57/BL6 mice liver.In mechanistic studies with the full-length 3’-UTR cloned into luciferase reporter or expression vectors,we showed that the 3’-UTR reduces PXR expression.From the miRNAs tested,miR-18a-5p inhibited both NR 112 expression and CYP3A4 gene induction.Importantly,we observed significant upregulation of miR-18a-5p expression 6 h after treatment with the PXR ligand rifampicin,which indicates a putative mechanism underlying NR1I2 negative feed-back regulation in hepatic cells.Additionally,glucocorticoids upregulated NR1I2 expression not only through the promoter region but also via 3’-UTR regulation,which likely involves downregulation of miR-18a-5p.We conclude that miR-18a-5p is involved in the down-regulation of NR1I2expression by its ligands and in the upregulation of NR1I2 mRNA expression by glucocorticoids in hepatic cells.
基金This study was supported by a grant from the National Natural Science Foundation of China （No. 30771778）.
文摘During the last decade, much progress has been made in exploring the mechanisms of alterations elicited by foreign compounds in xeno- and endobiotic metabolism regulated by the human nuclear pregnane X receptor （PXR）. PXR, identified as a human nuclear receptor in 1998 and generally regarded as a sensor activated by exogenous and endogenous chemicals, regulates a large number of enzymes and transporters involved in the response of mammals to their chemical environment.
基金National Natural Science Foundation of China(Grant Nos.82020108031,82404752,81730103,81573507 and 81973398)National Key Research and Development Program(Grant Nos.2017YFC0909300 and 2016YFC0905000,China)+7 种基金Guangdong Provincial Key Laboratory of Construction Foundation(Grant Nos.2017B030314030 and 2020B1212060034,China)Science and Technology Program of Guangzhou(Grant No.201607020031,China)National Engineering and Technology Research Center for New drug Druggability Evaluation Seed Program of Guangdong Province(Grant No.2017B090903004,China)111 project(Grant No.B16047,China)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515012549 and 2023A1515012667,China)Marine Medicine Innovation Platform for the Integration of Production and Education Project of Guangdong Provincial Education Department(No.2021CJPT014,China)Shenzhen Stability Support Project for Colleges and Universities(No.20220814205518001,China)Shenzhen Sustainable Development Project(No.KCXFZ20230731094501002,China).
文摘Alcoholic steatohepatitis (ASH) is a liver disease characterized by steatosis, inflammation, and necrosis of the liver tissue as a result of excessive alcohol consumption. Pregnane X receptor (PXR) is a xenobiotic nuclear receptor best known for its function in the transcriptional regulation of drug metabolism and disposition. Clinical reports suggested that the antibiotic rifampicin, a potent human PXR activator, is a contraindication in alcoholics, but the mechanism was unclear. In this study, we showed that the hepatic expression of fatty acid binding protein 4 (FABP4) was uniquely elevated in ASH patients and a mouse model of ASH. Pharmacological inhibiting FABP4 attenuated ASH in mice. Furthermore, treatment of mice with the mouse PXR agonist pregnenolon-16α-carbonitrile (PCN) induced the hepatic and circulating levels of FABP4 and exacerbated ASH in a PXR-dependent manner. Our mechanism study established FABP4 as a transcriptional target of PXR. Treatment with andrographolide, a natural compound and dual inhibitor of PXR and FABP4, alleviated mice from ASH. In summary, our results showed that the PXR-FABP4 gene regulatory axis plays an important role in the progression of ASH, which may have accounted for the contraindication of rifampicin in patients of alcoholic liver disease. Pharmacological inhibition of PXR and/or FABP4 may have its promise in the clinical management of ASH.
基金Acknowledgement This work was supported by the National Natural Science Foundation of China （30770237） and the Pro- gram for New Century Excellent Talents in University （NCET-05-0852）.
文摘Microbial transformation of pregnane-3β,16β,20-triol （1） by Cunninghamella echinulata afforded four previ- ously unreported polyhydroxylated steroids, namely pregnane-3β,14a,16β,20-tetrol （2）, pregnane-3-oxo-14a, 16β,20-triol （3）, pregnane-3-oxo-7β,16β,20-triol （4）, and pregnane-3fl,7β,16β,20-tetrol （5）. The structures of these metabolites were established by means of spectroscopic analysis （1D and 2D NMR as well as HRESIMS analysis）.
基金This work was supported by the USA National Center for Com-plementary and Integrative Health Grant R21AT011088(to X.Ma)in part by Grant U54AT008909(to M.F.Paine)+1 种基金in part by the USA National Institute of Allergy and Infectious Diseases Grant R01AI131983(to X.Ma)National Institute of Diabetes and Digestive and Kidney Diseases Grant R01DK126875(to X.Ma).
文摘Background and aims:The herbal supplement Gancao,also known as licorice,belongs to the genus Glycyrrhiza and has been used worldwide for its hepatoprotective effect.Recent studies have raised concerns about potential herb-drug interactions associated with Gancao via pregnane X receptor(PXR)-mediated induction of hepatic cytochrome P4503A4(CYP3A4).The current work aimed to determine the phytochemicals in Gancao that activate PXR and induce CYP3A4.Methods:DPX2 cells were used for cell-based PXR reporter assays.The phytochemicals in Gancao extract were identified using a metabolomics approach.The effects of PXR activators identified from in vitro studies were further investigated in PXR-and CYP3A4-humanized mouse models.Results:Gancao was verified to be a PXR-activating herb.Two major phytochemicals in Gancao,gly-cyrrhizin(GZ)and glycyrrhetinic acid(GA),did not activate PXR in the cell-based reporter assays.However,glabridin was shown to activate PXR in a dose-dependent manner.In vivo studies confirmed that GZ is not a PXR activator and glabridin is a weak PXR activator.Although GA did not active PXR in vitro,it induced CYP3A4 expression in a PXR-dependent manner in the PXR-and CYP3A4-humanized mice.
基金This work was supported by the US National Institute of Allergy and Infectious Diseases(R01AI131983)in part by the National Institute of Diabetes and Digestive and Kidney Diseases(DK090305).
文摘The pregnane X receptor(PXR)is a ligand activated nuclear receptor that is highly expressed in the liver and regulates many cellular functions including drug metabolism,endobiotic metabolism,oxidative stress response,apoptosis,inflammation,cell proliferation and regeneration.PXR activation promotes drug-induced liver injury(DILI)through its ability to increase the expression of phaseⅠand phaseⅡdrug metabolizing enzymes.The PXR also increases lipid synthesis and fatty acid uptake into the liver,leading to lipid accumulation and steatosis.In recent years,PXR has been explored as an important target in DILI and liver diseases.This review will highlight the roles of PXR in modulating DILI.PXR polymorphisms that have been associated with DILI will also be discussed.
基金This study was funded by the National Natural Science Foun-dation of China(Grant Nos.81772972,81672731,81572703,81572451)Natural Science Foundation of Guangdong Prov-ince(Grant Nos.2021A1515010776,2015A030313449)+1 种基金Science and Technology Planning Project of Guangdong Province“Public Research and Capacity Building”Special Project Fund(Grant No.2014A020212285)Department of Education,Guangdong Government under the Toptier University Development Scheme for Research and Control of Infectious Diseases(Grant Nos.2016026,2015060,2015089).
文摘Background and Aims:Hepatitis B virus(HBV)infection has been found to increase hepatocellular sensitivity to carcinogenic xenobiotics,by unknown mechanisms,in the generation of hepatocellular carcinoma.The pregnane X receptor(PXR)is a key regulator of the body’s defense against xenobiotics,including xenobiotic carcinogens and clinical drugs.In this study,we aimed to investigate the molecular mechanisms of HBV X protein(HBx)-PXR signaling in the synergistic effects of chemical carcinogens in HBV-associated hepatocarcinogenesis.Methods:The expression profile of PXR-cytochrome p4503A4(CYP3A4)signaling was determined by PCR,western blotting,and tissue microarray.Cell viability and aflatoxin B1(AFB1)cytotoxicity were measured using the cell counting kit-8 assay.Target gene expression was evaluated using transient transfection and real time-PCR.The genotoxicity of AFB1 was assessed in newborn mice with a single dose of AFB1.Results:HBx enhanced the hepatotoxicity of AFB1 by activating CYP3A4 and reducing glutathione Stransferase Mu 1(GSTM1)in cell lines.Activation of PXR by pregnenolone 16α-carbonitrile increased AFB1-induced liver tumor incidence by up-regulating oncogenic KRAS to enhance interleukin(IL)-11:IL-11 receptor subunit alpha-1(IL11RA-1)-mediated inflammation in an HBx transgenic model.Conclusions:Our finding regarding AFB1 toxicity enhancement by an HBx-PXR-CYP3A4/GSTM1-KRASIL11:IL11RA signaling axis provides a rational explanation for the synergistic effects of chemical carcinogens in HBV infection-associated hepatocarcinogenesis.
