RESUMEN
Pregnane X receptor (PXR) is a xenobiotic-sensing nuclear receptor that plays a key role in drug metabolism. Recently, PXR was found to attenuate the development of liver cancer by suppressing epithelial-mesenchymal transition (EMT) in liver cancer cells in a mouse model of two-stage chemical carcinogenesis. To elucidate the role of PXR in the EMT of liver cancer cells, we focused on its role in hepatic stellate cells (HSCs), which are components of the tumor microenvironment in hepatocellular carcinoma (HCC). Human HSC-derived LX-2 cells stably expressed destabilization domain (DD)-fused human PXR (hPXR-LX2 cells). Human HCC-derived HepG2 cells were transfected with the EMT marker VIM promoter-regulated reporter plasmid and co-cultured with hPXR-LX2 cells or treated with hPXR-LX2-derived conditioned medium (CM). Co-culture or CM treatment increased reporter activity in HepG2 cells. This induction was attenuated upon PXR activation in hPXR-LX2 cells by treatment with the DD-stabilizing chemical Shield-1 and the human PXR ligand rifampicin. PXR activation in hPXR-LX2 cells exhibited inhibition of TGF-ß1-induced transdifferentiation, supported by observations of morphological changes and protein or mRNA levels of the transdifferentiation markers COL1A1 and FN1. PXR activation in hPXR-LX2 cells also attenuated the mRNA levels of the key transdifferentiation factor, POSTN. Treatment of hPXR-LX2 cells with recombinant POSTN restored the PXR-mediated suppression of transdifferentiation. Reporter assays with the POSTN promoter showed that PXR inhibited the NF-κB-mediated transcription of POSTN. Consequently, PXR activation in HSCs is expected to inhibit transdifferentiation by down-regulating POSTN expression, thereby suppressing EMT of liver cancer cells.
Asunto(s)
Moléculas de Adhesión Celular , Transdiferenciación Celular , Regulación hacia Abajo , Células Estrelladas Hepáticas , Receptor X de Pregnano , Humanos , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Células Estrelladas Hepáticas/metabolismo , Células Estrelladas Hepáticas/efectos de los fármacos , Células Estrelladas Hepáticas/patología , Transdiferenciación Celular/efectos de los fármacos , Células Hep G2 , Regulación hacia Abajo/efectos de los fármacos , Moléculas de Adhesión Celular/genética , Moléculas de Adhesión Celular/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patología , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/genética , Transición Epitelial-Mesenquimal/efectos de los fármacos , PeriostinaRESUMEN
5ß-Dihydrosteroids are produced by the reduction of Δ4-3-ketosteroids catalyzed by steroid 5ß-reductase (AKR1D1). By analogy with steroid 5α-reductase, genetic deficiency exists in AKR1D1 which leads to errors in newborn metabolism and in this case to bile acid deficiency. Also, like the 5α-dihydrosteroids (e.g., 5α-dihydrotestosterone), the 5ß-dihydrosteroids produced by AKR1D1 are not inactive but regulate ligand access to nuclear receptors, can act as ligands for nuclear and membrane-bound receptors, and regulate ion-channel opening. For example, 5ß-reduction of cortisol and cortisone yields the corresponding 5ß-dihydroglucocorticoids which are inactive on the glucocorticoid receptor (GR) and provides an additional mechanism of pre-receptor regulation of ligands for the GR in liver cells. By contrast, 5ß-pregnanes can act as neuroactive steroids at the GABAA and NMDA receptors and at low-voltage-activated calcium channels, act as tocolytic agents, have analgesic activity and act as ligands for PXR, while bile acids act as ligands for FXR and thereby control cholesterol homeostasis. The 5ß-androstanes also have potent vasodilatory properties and work through blockade of Ca2+ channels. Thus, a preference for 5ß-dihydrosteroids to work at the membrane level exists via a variety of mechanisms. This article reviews the field and identifies gaps in knowledge to be addressed in future research.
Asunto(s)
Ácidos y Sales Biliares , Humanos , Animales , Ácidos y Sales Biliares/metabolismo , Oxidorreductasas/metabolismoRESUMEN
Our previous study shows that activation of pregnane X receptor (PXR) exerts hepatoprotection against lithocholic acid (LCA)-induced cholestatic liver injury. In this study we investigated whether PXR activation could inhibit hepatocyte pyroptosis, as well as the underlying mechanisms. Male mice were treated with mouse PXR agonist pregnenolone 16α-carbonitrile (PCN, 50 mg·kg-1·d-1, i.p.) for 7 days, and received LCA (125 mg/kg, i.p., bid) from D4, then sacrificed 12 h after the last LCA injection. We showed that LCA injection resulted in severe cholestatic liver injury characterized by significant increases in gallbladder size, hepatocellular necrosis, and neutrophil infiltration with a mortality rate of 68%; PCN treatment significantly inhibited hepatocyte pyroptosis during LCA-induced cholestatic liver injury, as evidenced by reduced serum lactic dehydrogenase (LDH) levels, TUNEL-positive cells and hepatocyte membrane damage. Furthermore, PXR activation suppressed both the NOD-like receptor protein 3 (NLRP3) inflammasome-induced canonical pyroptosis and the apoptosis protease activating factor-1 (APAF-1) pyroptosome-induced non-canonical pyroptosis. Inhibition of the nuclear factor kappa B (NF-κB) and forkhead box O1 (FOXO1) signaling pathways was also observed following PXR activation. Notably, dual luciferase reporter assay showed that PXR activation inhibited the transcriptional effects of NF-κB on NLRP3, as well as FOXO1 on APAF-1. Our results demonstrate that PXR activation protects against cholestatic liver injury by inhibiting the canonical pyroptosis through the NF-κB-NLRP3 axis and the non-canonical pyroptosis through the FOXO1-APAF-1 axis, providing new evidence for PXR as a prospective anti-cholestatic target.
RESUMEN
Rifampicin is a model ligand of the pregnane X receptor (PXR), the nuclear receptor involved in the regulation of cytochrome P450 3A4 (CYP3A4). Rifampicin forms several degradation products and metabolites of which 25-desacetylrifampicin is the most abundant in vivo. Here, we aimed to study both the stability and metabolism of rifampicin in media and 2D and 3D primary human hepatocytes (PHHs). Additionally, we analyzed interactions of rifampicin derivatives with PXR. We described that rifampicin gradually degrades by more than 50 % in the medium partly into quinone over 72 h. We observed 25-desacetylrifampicin in 2D PHHs but not in 3D PHHs. Contrary, rifampicin was converted into quinone in a one-direction process in media of 3D PHHs. The potency of rifampicin and its derivatives to activate human PXR was arranged as follows: 3-formylrifamycin SV > rifampicin quinone > rifampicin > rifampicin N-oxide > 25-desacetylrifampicin, respectively, but none activates mouse and rat PXR. The binding differences between rifampicin and 25-desacetylrifampicin were modeled in silico. Finally, we showed that overexpressed uptake organic anion transporting polypeptide 1B1 (OATP1B1) potentiated activation of PXR by rifampicin and rifampicin quinone, but overexpressed efflux multidrug resistance protein 1 (MDR1) decreased PXR activation by all derivatives.
RESUMEN
Pregnane X receptor (PXR) is a heterologous biosensor that is involved in the metabolic pathway of environmental pollutants, regulating the transcription of genes involved in biotransformation. There are significant differences in the selectivity and specificity of organic pollutants (OPs) toward polar bear PXR (pbPXR) and human PXR (hPXR), but the detailed dynamical characteristics of their interactions are unclear. Homology Modeling, molecular docking, molecular dynamics simulation, and free energy calculation were used to analyze the recognition of pbPXR and hPXR by three OPs: BPA, chlordane and toxaphene. Comparing interaction patterns along with binding free energy of pbPXR and hPXR with these three OPs revealed that although pbPXR and hPXR interact similar with these three OPs, these OPs have different effects on the internal dynamics of pbPXR and hPXR. This results in significant alterations in the interaction of key residues near Leu209, Met243, Phe288, Met323, and His407 with OPs, thereby influencing their binding energy. Non-polar interactions, especially van der Waals interactions, were found to be the dominating factors in interacting of these OPs with PXRs. The region surrounding these key residues facilitates hydrophobic contacts with PXR, which are crucial for the selective activation of PXRs in different species by these three OPs. These findings are of significant guidance in understanding the impacts of environmental endocrine disruptors on different organisms.
Asunto(s)
Contaminantes Ambientales , Receptor X de Pregnano , Receptores de Esteroides , Animales , Humanos , Contaminantes Ambientales/química , Contaminantes Ambientales/metabolismo , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/química , Unión Proteica , Receptores de Esteroides/metabolismo , Receptores de Esteroides/química , UrsidaeRESUMEN
The pregnane X receptor (PXR, NR1I2), a xenobiotic-sensing nuclear receptor signaling potentiates ethanol (EtOH)-induced hepatotoxicity in male mice, however, how PXR signaling modulates EtOH-induced hepatotoxicity in female mice is unknown. Wild type (WT) and Pxr-null mice received 5 % EtOH-containing diets or paired-fed control diets for 8 weeks followed by assessment of liver injury, EtOH elimination rates, histology, and changes in gene and protein expression; microarray and bioinformatic analyses were also employed to identify PXR targets in chronic EtOH-induced hepatotoxicity. In WT females, EtOH ingestion significantly increased serum ethanol and alanine aminotransferase (ALT) levels, hepatic Pxr mRNA, constitutive androstane receptor activation, Cyp2b10 mRNA and protein, oxidative stress, endoplasmic stress (phospho-elF2α) and pro-apoptotic (Bax) protein expression. Unexpectedly, EtOH-fed female Pxr-null mice displayed increased EtOH elimination and elevated levels of hepatic acetaldehyde detoxifying aldehyde dehydrogenase 1a1 (Aldh1a1) mRNA and protein, EtOH-metabolizing alcohol dehydrogenase 1 (ADH1), and lipid suppressing microsomal triglyceride transport protein (MTP) protein, aldo-keto reductase 1b7 (Akr1b7) and Cyp2a5 mRNA, but suppressed CYP2B10 protein levels, with evidence of protection against chronic EtOH-induced oxidative stress and hepatotoxicity. While liver injury was not different between the two WT sexes, female sex may suppress EtOH-induced macrovesicular steatosis in the liver. Several genes and pathways important in retinol and steroid hormone biosynthesis, chemical carcinogenesis, and arachidonic acid metabolism were upregulated by EtOH in a PXR-dependent manner in both sexes. Together, these data establish that female Pxr-null mice are resistant to chronic EtOH-induced hepatotoxicity and unravel the PXR-dependent and -independent mechanisms that contribute to EtOH-induced hepatotoxicity.
Asunto(s)
Etanol , Ratones Noqueados , Receptor X de Pregnano , Animales , Femenino , Etanol/toxicidad , Ratones , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Ratones Endogámicos C57BL , Masculino , Hígado/metabolismo , Hígado/efectos de los fármacos , Hígado/patología , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismoRESUMEN
Background: Cannabidiol (CBD), a non-psychoactive phytocannabinoid of cannabis, is therapeutically used as an analgesic, anti-convulsant, anti-inflammatory, and anti-psychotic drug. There is a growing concern about the adverse side effects posed by CBD usage. Pregnane X receptor (PXR) is a nuclear receptor activated by a variety of dietary steroids, pharmaceutical agents, and environmental chemicals. In addition to the role in xenobiotic metabolism, the atherogenic and dyslipidemic effects of PXR have been revealed in animal models. CBD has a low affinity for cannabinoid receptors, thus it is important to elucidate the molecular mechanisms by which CBD activates cellular signaling and to assess the possible adverse impacts of CBD on pro-atherosclerotic events in cardiovascular system, such as dyslipidemia. Objective: Our study aims to explore the cellular and molecular mechanisms by which exposure to CBD activates human PXR and increases the risk of dyslipidemia. Methods: Both human hepatic and intestinal cells were used to test if CBD was a PXR agonist via cell-based transfection assay. The key residues within PXR's ligand-binding pocket that CBD interacted with were investigated using computational docking study together with site-directed mutagenesis assay. The C57BL/6 wildtype mice were orally fed CBD in the presence of PXR antagonist resveratrol (RES) to determine how CBD exposure could change the plasma lipid profiles in a PXR-dependent manner. Human intestinal cells were treated with CBD and/or RES to estimate the functions of CBD in cholesterol uptake. Results: CBD was a selective agonist of PXR with higher activities on human PXR than rodents PXRs and promoted the dissociation of human PXR from nuclear co-repressors. The key amino acid residues Met246, Ser247, Phe251, Phe288, Trp299, and Tyr306 within PXR's ligand binding pocket were identified to be necessary for the agonistic effects of CBD. Exposure to CBD increased the circulating total cholesterol levels in mice which was partially caused by the induced expression levels of the key intestinal PXR-regulated lipogenic genes. Mechanistically, CBD induced the gene expression of key intestinal cholesterol transporters, which led to the increased cholesterol uptake by intestinal cells. Conclusion: CBD was identified as a selective PXR agonist. Exposure to CBD activated PXR signaling and increased the atherogenic cholesterol levels in plasma, which partially resulted from the ascended cholesterol uptake by intestinal cells. Our study provides potential evidence for the future risk assessment of CBD on cardiovascular disease, such as dyslipidemia.
Asunto(s)
Cannabidiol , Colesterol , Ratones Endogámicos C57BL , Receptor X de Pregnano , Receptor X de Pregnano/metabolismo , Animales , Humanos , Ratones , Cannabidiol/farmacología , Colesterol/metabolismo , Masculino , Mucosa Intestinal/metabolismo , Mucosa Intestinal/efectos de los fármacos , Simulación del Acoplamiento MolecularRESUMEN
Human pregnane X receptor (PXR) is critical for regulating the expression of key drug-metabolizing enzymes such as CYP3A and CYP2C. Our recent study revealed that treatment with rodent-specific PXR agonist pregnenolone-16α-carbonitrile (PCN) significantly induced hepatomegaly and promoted liver regeneration after two-thirds partial hepatectomy (PHx) in mice. However, it remains unclear whether PXR activation induces hepatomegaly and liver regeneration and simultaneously promotes metabolic function of the liver. Here, we investigated the metabolism activity of CYP1A2, CYP3A1/2 and CYP2C6/11 during PXR activation-induced liver enlargement and regeneration in rats after cocktail dosing of CYP probe drugs. For PCN-induced hepatomegaly, a notable increase in the metabolic activity of CYP3A1/2 and CYP2C6/11, as evidenced by the plasma exposure of probe substrates and the AUC ratios of the characteristic metabolites to its corresponding probe substrates. The metabolic activity of CYP1A2, CYP3A1/2 and CYP2C6/11 decreased significantly after PHx. However, PCN treatment obviously enhanced the metabolic activity of CYP2C6/11 and CYP3A1/2 in PHx rats. Furthermore, the protein expression levels of CYP3A1/2 and CYP2C6/11 in liver were up-regulated. Taken together, this study demonstrates that PXR activation not only induces hepatomegaly and liver regeneration in rats, but also promotes the protein expression and metabolic activity of the PXR downstream metabolizing enzymes such as CYP3A1/2 and CYP2C6/11 in the body.
Asunto(s)
Citocromo P-450 CYP3A , Hepatomegalia , Regeneración Hepática , Hígado , Receptor X de Pregnano , Carbonitrilo de Pregnenolona , Animales , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Regeneración Hepática/efectos de los fármacos , Masculino , Citocromo P-450 CYP3A/metabolismo , Carbonitrilo de Pregnenolona/farmacología , Hígado/metabolismo , Hígado/enzimología , Hígado/efectos de los fármacos , Ratas , Hepatomegalia/metabolismo , Hepatomegalia/patología , Hidrocarburo de Aril Hidroxilasas/metabolismo , Hidrocarburo de Aril Hidroxilasas/genética , Familia 2 del Citocromo P450/metabolismo , Familia 2 del Citocromo P450/genética , Ratas Sprague-Dawley , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP1A2/genética , Esteroide 16-alfa-Hidroxilasa/metabolismo , Esteroide 16-alfa-Hidroxilasa/genética , Esteroide 12-alfa-Hidroxilasa/metabolismo , Esteroide 12-alfa-Hidroxilasa/genética , HepatectomíaRESUMEN
The pregnane X receptor (PXR) is a nuclear hormone receptor that plays a pivotal role in regulating gene expression in response to various ligands, particularly xenobiotics. In this context, the aim of this study was to shed light on the ligand affinity and functions of four NR1J1 paralogs identified in the marine mussel Mytilus galloprovincialis, employing a dual-luciferase reporter assay. To achieve this, the activation patterns of these paralogs in response to various toxins, including freshwater cyanotoxins (Anatoxin-a, Cylindrospermopsin, and Microcystin-LR, -RR, and -YR) and marine algal toxins (Nodularin, Saxitoxin, and Tetrodotoxin), alongside natural compounds (Saint John's Wort, Ursolic Acid, and 8-Methoxypsoralene) and microalgal extracts (Tetraselmis, Isochrysis, LEGE 95046, and LEGE 91351 extracts), were studied. The investigation revealed nuanced differences in paralog response patterns, highlighting the remarkable sensitivity of MgaNR1J1γ and MgaNR1J1δ paralogs to several toxins. In conclusion, this study sheds light on the intricate mechanisms of xenobiotic metabolism and detoxification, particularly focusing on the role of marine mussel NR1J1 in responding to a diverse array of compounds. Furthermore, comparative analysis with human PXR revealed potential species-specific adaptations in detoxification mechanisms, suggesting evolutionary implications. These findings deepen our understanding of PXR-mediated metabolism mechanisms, offering insights into environmental monitoring and evolutionary biology research.
Asunto(s)
Toxinas Marinas , Mytilus , Receptor X de Pregnano , Animales , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Mytilus/metabolismo , Mytilus/genética , Humanos , Microcistinas/metabolismo , Microalgas/metabolismo , Microalgas/genética , Xenobióticos/metabolismo , Toxinas Bacterianas/metabolismo , Toxinas de CianobacteriasRESUMEN
Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Pregnane X receptor (PXR), a xenobiotic-sensing nuclear receptor, plays a critical role in the metabolism of endogenous and exogenous substances in the liver. Here, we investigate whether PXR plays a role in pathogenesis of HCC. We show that liver tumors were developed in diethylnitrosamine (DEN)-treated in PXR knockout (KO) mice. Hepatic levels of prostaglandin F2α (PGF2α) and aldo-keto reductase family 1 member C18 (Akr1c18), a prostaglandin synthase of catalyzing reduction of PGH2 to PGF2α, were significantly elevated in DEN-treated PXR KO mice. Hepatic mRNA levels of alpha fetoprotein (AFP), cyclin D1 (Ccnd1), fibroblast growth factor 21 (FGF21), and inflammatory cytokine interleukin 6 (IL-6) were significantly increased in DEN-treated PXR KO mice. Other members of Akr1c family, liver metabolizing enzymes including Cyp1a2, Cyp2b10 and Cyp3a11, and bile acid synthesis enzyme Cyp7a1 mRNA levels were significantly decreased in DEN-treated PXR KO mice. Our findings revealed that PXR deficiency promoted DEN-induced HCC in mice via induction of Akr1c18 expression and PGF2α levels and the increased PGF2α levels synthetized by Akr1c18 enhanced hepatocytes proliferation and induced inflammatory cytokine production, which accelerated liver tumor development after DEN treatment, suggesting that PXR deficiency may create a microenvironment that is more prone to DEN-induced liver tumors and targeting PXR and Akr1c18 to reduce PGF2α biosynthesis may be a potential and novel therapeutic strategy for HCC.
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Dinoprost , Receptor X de Pregnano , Animales , Humanos , Masculino , Ratones , Carcinogénesis/metabolismo , Carcinogénesis/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/inducido químicamente , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patología , Dietilnitrosamina/toxicidad , Dinoprost/metabolismo , Dinoprost/biosíntesis , Regulación Neoplásica de la Expresión Génica , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/inducido químicamente , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patología , Neoplasias Hepáticas Experimentales/metabolismo , Neoplasias Hepáticas Experimentales/inducido químicamente , Neoplasias Hepáticas Experimentales/genética , Neoplasias Hepáticas Experimentales/patología , Ratones Endogámicos C57BL , Ratones Noqueados , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genéticaRESUMEN
The activation of pregnane X receptor (PXR) or peroxisome proliferator-activated receptor α (PPARα) can induce liver enlargement. Recently, we reported that PXR or PPARα activation-induced hepatomegaly depends on yes-associated protein (YAP) signaling and is characterized by hepatocyte hypertrophy around the central vein area and hepatocyte proliferation around the portal vein area. However, it remains unclear whether PXR or PPARα activation-induced hepatomegaly can be reversed after the withdrawal of their agonists. In this study, we investigated the regression of enlarged liver to normal size following the withdrawal of PCN or WY-14643 (typical agonists of mouse PXR or PPARα) in C57BL/6 mice. The immunohistochemistry analysis of CTNNB1 and KI67 showed a reversal of hepatocyte size and a decrease in hepatocyte proliferation after the withdrawal of agonists. In details, the expression of PXR or PPARα downstream proteins (CYP3A11, CYP2B10, ACOX1, and CYP4A) and the expression of proliferation-related proteins (CCNA1, CCND1, and PCNA) returned to the normal levels. Furthermore, YAP and its downstream proteins (CTGF, CYR61, and ANKRD1) also restored to the normal states, which was consistent with the change in liver size. These findings demonstrate the reversibility of PXR or PPARα activation-induced hepatomegaly and provide new data for the safety of PXR and PPARα as drug targets.
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Proliferación Celular , Hepatocitos , Hepatomegalia , Hígado , PPAR alfa , Receptor X de Pregnano , Pirimidinas , Proteínas Señalizadoras YAP , Animales , Masculino , Ratones , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Hidrocarburo de Aril Hidroxilasas , beta Catenina/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Proliferación Celular/efectos de los fármacos , Citocromo P-450 CYP3A , Citocromo P-450 CYP4A/metabolismo , Citocromo P-450 CYP4A/genética , Familia 2 del Citocromo P450 , Familia 4 del Citocromo P450/genética , Familia 4 del Citocromo P450/metabolismo , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Hepatocitos/patología , Hepatomegalia/inducido químicamente , Hepatomegalia/metabolismo , Hepatomegalia/patología , Antígeno Ki-67/metabolismo , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/patología , Proteínas de la Membrana , Ratones Endogámicos C57BL , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , PPAR alfa/agonistas , PPAR alfa/metabolismo , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Pirimidinas/farmacología , Transducción de Señal/efectos de los fármacos , Esteroide Hidroxilasas , Proteínas Señalizadoras YAP/metabolismoRESUMEN
Deoxynivalenol (DON) is a prevalent toxin causing severe liver damage through hepatocellular oxidative stress. However, the underlying mechanisms and effective therapeutic approaches remain unknown. Here, the unique role of the xenobiotic metabolism factor pregnane X receptor (PXR) in mediating DON-induced hepatocellular oxidative stress is investigated. Treatment with the PXR agonist 3-indole-propionic acid (IPA) alleviates DON-induced oxidative stress and liver injury both in vitro and in vivo. Mechanistically, it is discovered for the first time that PXR agonist IPA directly transactivates the m6A demethylase FTO expression, leading to site-specific demethylation and decreased abundance of YTHDC1-bound Malat1 lncRNA at single-nucleotide resolution. The diminished m6A modification of Malat1 lncRNA reduces its stability and augments antioxidant pathways governed by NRF2, consequently mitigating DON-induced liver injury. Furthermore, Malat1 knockout mice exhibit decreased DON-induced liver injury, emphasizing the role of Malat1 lncRNA in oxidative stress. Collectively, the findings establish that PXR-mediated m6A-dependent Malat1 lncRNA expression determines hepatocyte oxidative stress via m6A demethylase FTO, providing valuable insights into the potential mechanisms underlying DON-induced liver injury and offers potential therapeutic strategies for its treatment.
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Desmetilación , Ratones Noqueados , Estrés Oxidativo , Receptor X de Pregnano , ARN Largo no Codificante , Tricotecenos , Animales , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genética , Ratones , Tricotecenos/toxicidad , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Modelos Animales de Enfermedad , Masculino , Ratones Endogámicos C57BL , Hígado/metabolismo , Hígado/efectos de los fármacos , HumanosRESUMEN
Succinate dehydrogenase inhibitors (SDHIs) are widely-used fungicides, to which humans are exposed and for which putative health risks are of concern. In order to identify human molecular targets for these agrochemicals, the interactions of 15 SDHIs with expression and activity of human cytochrome P-450 3A4 (CYP3A4), a major hepatic drug metabolizing enzyme, were investigated in vitro. 12/15 SDHIs, i.e., bixafen, boscalid, fluopyram, flutolanil, fluxapyroxad, furametpyr, isofetamid, isopyrazam, penflufen, penthiopyrad, pydiflumetofen and sedaxane, were found to enhance CYP3A4 mRNA expression in human hepatic HepaRG cells and primary human hepatocytes exposed for 48â¯h to 10⯵M SDHIs, whereas 3/15 SDHIs, i.e., benzovindiflupyr, carboxin and thifluzamide, were without effect. The inducing effects were concentrations-dependent for boscalid (EC50=22.5⯵M), fluopyram (EC50=4.8⯵M) and flutolanil (EC50=53.6⯵M). They were fully prevented by SPA70, an antagonist of the Pregnane X Receptor, thus underlining the implication of this xenobiotic-sensing receptor. Increase in CYP3A4 mRNA in response to SDHIs paralleled enhanced CYP3A4 protein expression for most of SDHIs. With respect to CYP3A4 activity, it was directly inhibited by some SDHIs, including bixafen, fluopyram, fluxapyroxad, isofetamid, isopyrazam, penthiopyrad and sedaxane, which therefore appears as dual regulators of CYP3A4, being both inducer of its expression and inhibitor of its activity. The inducing effect nevertheless predominates for these SDHIs, except for isopyrazam and sedaxane, whereas boscalid and flutolanil were pure inducers of CYP3A4 expression and activity. Most of SDHIs appear therefore as in vitro inducers of CYP3A4 expression in cultured hepatic cells, when, however, used at concentrations rather higher than those expected in humans in response to environmental or dietary exposure to these agrochemicals.
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Citocromo P-450 CYP3A , Hepatocitos , Succinato Deshidrogenasa , Humanos , Citocromo P-450 CYP3A/metabolismo , Citocromo P-450 CYP3A/genética , Hepatocitos/efectos de los fármacos , Succinato Deshidrogenasa/antagonistas & inhibidores , Succinato Deshidrogenasa/metabolismo , Fungicidas Industriales/toxicidad , ARN Mensajero/metabolismo , ARN Mensajero/genética , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/toxicidad , Línea CelularRESUMEN
Pregnane X receptor (PXR) has been considered as a promising therapeutic target for cholestasis due to its crucial regulation in bile acid biosynthesis and metabolism. To search promising natural PXR agonists, the PXR agonistic activities of five traditional Chinese medicines (TCMs) with hepatoprotective efficacy were assayed, and Hypericum japonicum as the most active one was selected for subsequent phytochemical investigation, which led to the isolation of eight nonaromatic acylphloroglucinol-terpenoid adducts including seven new compounds (1 - 4, 5a, 5b and 6). Their structures including absolute configurations were determined by comprehensive spectroscopic, computational and X-ray diffraction analysis. Meanwhile, the PXR agonistic activities of aplenty compounds were evaluated via dual-luciferase reporter assay, RT-qPCR and immunofluorescence. Among them, compounds 1 - 4 showed more potent activity than the positive drug rifampicin. Furthermore, the molecular docking revealed that 1 - 4 were docked well on the PXR ligand binding domain and formed hydrogen bonds with amino acid residues Gln285, Ser247 and His409. This investigation revealed that H. japonicum may serve as a rich source of natural PXR agonists.
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Hypericum , Simulación del Acoplamiento Molecular , Floroglucinol , Receptor X de Pregnano , Hypericum/química , Receptor X de Pregnano/agonistas , Receptor X de Pregnano/metabolismo , Humanos , Floroglucinol/farmacología , Floroglucinol/química , Floroglucinol/análogos & derivados , Relación Estructura-Actividad , Estructura Molecular , Terpenos/farmacología , Terpenos/química , Terpenos/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Descubrimiento de Drogas , Células Hep G2RESUMEN
This review explores the likely clinical impact of Pregnane X Receptor (PXR) activation by vitamin K on human health. PXR, initially recognized as a master regulator of xenobiotic metabolism in liver, emerges as a key regulator influencing intestinal homeostasis, inflammation, oxidative stress, and autophagy. The activation of PXR by vitamin K highlights its role as a potent endogenous and local agonist with diverse clinical implications. Recent research suggests that the vitamin K-mediated activation of PXR highlights this vitamin's potential in addressing pathophysiological conditions by promoting hepatic detoxification, fortifying gut barrier integrity, and controlling pro-inflammatory and apoptotic pathways. PXR activation by vitamin K provides an intricate association with cancer cell survival, particularly in colorectal and liver cancers, to provide new insights into potential novel therapeutic strategies. Understanding the clinical implications of PXR activation by vitamin K bridges molecular mechanisms with health outcomes, further offering personalized therapeutic approaches for complex diseases.
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Receptor X de Pregnano , Transducción de Señal , Vitamina K , Humanos , Relevancia Clínica , Salud , Receptor X de Pregnano/metabolismo , Vitamina K/metabolismoRESUMEN
Bone homeostasis is maintained by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. A dramatic decrease in estrogen levels in postmenopausal women leads to osteoclast overactivation, impaired bone homeostasis, and subsequent bone loss. Changes in the gut microbiome affect bone mineral density. However, the role of the gut microbiome in estrogen deficiency-induced bone loss and its underlying mechanism remain unknown. In this study, we found that the abundance of Clostridium sporogenes (C. spor.) and its derived metabolite, indole propionic acid (IPA), were decreased in ovariectomized (OVX) mice. In vitro assays suggested that IPA suppressed osteoclast differentiation and function. At the molecular level, IPA suppressed receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced pregnane X receptor (PXR) ubiquitination and degradation, leading to increased binding of remaining PXR with P65. In vivo daily IPA administration or repeated C. spor. colonization protected against OVX-induced bone loss. To protect live bacteria from the harsh gastric environment and delay the emptying of orally administered C. spor. from the intestine, a C. spor.-encapsulated silk fibroin (SF) hydrogel system was developed, which achieved bone protection in OVX mice comparable to that achieved with repeated germ transplantation or daily IPA administration. Overall, we found that gut C. spor.-derived IPA was involved in estrogen deficiency-induced osteoclast overactivation by regulating the PXR/P65 complex. The C. spor.-encapsulated SF hydrogel system is a promising tool for combating postmenopausal osteoporosis without the disadvantages of repeated germ transplantation.
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Resorción Ósea , Clostridium , Osteoclastos , Propionatos , Humanos , Femenino , Ratones , Animales , Osteoclastos/metabolismo , Receptor X de Pregnano/metabolismo , Resorción Ósea/metabolismo , Osteogénesis , Estrógenos/metabolismo , Indoles/metabolismo , Hidrogeles , Ligando RANK/metabolismo , Diferenciación CelularRESUMEN
Liver regeneration after liver tumor resection or liver transplantation is crucial, the remaining liver frequently fails to regenerate in some patients. Oleanolic acid (OA), a pentacyclic triterpenoid compound which has been shown to protect against various liver diseases. However, the effect of OA on liver regeneration after partial hepatectomy (PHx) is still unclear. In this study, the results showed that OA (50 mg/kg, twice daily) treatment induced liver mass restoration and increased the liver-to-body weight ratio of mice following PHx. Meanwhile, OA promoted hepatocyte proliferation and increased the number of BrdU-, Ki67-and PCNA-positive cells. Furthermore, OA increased the nuclear accumulation of PXR and induced the expression of PXR downstream proteins such as CYP3A11, UGT1A1 and GSTM2 in mice, as well as in AML12 and HepRG cells. Luciferase reporter assay and nuclear localization of PXR further demonstrated the effect of OA on PXR activation in vitro. Molecular docking simulation showed that OA could interact with the PXR active sites. Moreover, OA inhibited the expression of FOXO1, RBL2 and CDKN1B, and increased the expression of PCNA, CCND1 and CCNE1 in vivo and in vitro. Silencing of Pxr further confirmed that OA-mediated upregulation of proliferation-related proteins depended on PXR. The current study illustrated that OA exhibited a significant promoting effect on liver regeneration following PHx, potentially through regulation of the PXR signaling pathway to accelerate liver recovery.
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Hepatectomía , Ácido Oleanólico , Humanos , Ratones , Animales , Regeneración Hepática , Receptor X de Pregnano/metabolismo , Ácido Oleanólico/farmacología , Hepatocitos , Antígeno Nuclear de Célula en Proliferación/metabolismo , Simulación del Acoplamiento Molecular , Hígado , Transducción de Señal , Ratones Endogámicos C57BLRESUMEN
Obesity is a significant risk factor for several chronic diseases. However, pre-menopausal females are protected against high-fat diet (HFD)-induced obesity and its adverse effects. The pregnane X receptor (PXR, NR1I2), a xenobiotic-sensing nuclear receptor, promotes short-term obesity-associated liver disease only in male mice but not in females. Therefore, the current study investigated the metabolic and pathophysiological effects of a long-term 52-week HFD in female wild-type (WT) and PXR-KO mice and characterized the PXR-dependent molecular pathways involved. After 52 weeks of HFD ingestion, the body and liver weights and several markers of hepatotoxicity were significantly higher in WT mice than in their PXR-KO counterparts. The HFD-induced liver injury in WT female mice was also associated with upregulation of the hepatic mRNA levels of peroxisome proliferator-activated receptor gamma (Pparg), its target genes, fat-specific protein 27 (Fsp27), and the liver-specific Fsp27b involved in lipid accumulation, apoptosis, and inflammation. Notably, PXR-KO mice displayed elevated hepatic Cyp2a5 (anti-obesity gene), aldo-keto reductase 1b7 (Akr1b7), glutathione-S-transferase M3 (Gstm3) (antioxidant gene), and AMP-activated protein kinase (AMPK) levels, contributing to protection against long-term HFD-induced obesity and inflammation. RNA sequencing analysis revealed a general blunting of the transcriptomic response to HFD in PXR-KO compared to WT mice. Pathway enrichment analysis demonstrated enrichment by HFD for several pathways, including oxidative stress and redox pathway, cholesterol biosynthesis, and glycolysis/gluconeogenesis in WT but not PXR-KO mice. In conclusion, this study provides new insights into the molecular mechanisms by which PXR deficiency protects against long-term HFD-induced severe obesity and its adverse effects in female mice.
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Dieta Alta en Grasa , Hígado , Masculino , Femenino , Ratones , Animales , Receptor X de Pregnano/genética , Receptor X de Pregnano/metabolismo , Dieta Alta en Grasa/efectos adversos , Ratones Endogámicos C57BL , Aumento de Peso , Obesidad/metabolismo , Inflamación/metabolismo , Ratones NoqueadosRESUMEN
Endotoxemia-related acute liver injury has a poor prognosis and high mortality, and macrophage polarization plays a central role in the pathological process. Pregnane X receptor (PXR) serves as a nuclear receptor and xenosensor, safeguarding the liver from toxic stimuli. However, the effect and underlying mechanism of PXR activation on endotoxemic liver injury remain largely unknown. Here, the expression of PXR is reported in human and murine macrophages, and PXR activation modified immunotypes of macrophages. Moreover, PXR activation significantly attenuated endotoxemic liver injury and promoted macrophage M2 polarization. Macrophage depletion by GdCl3 confirmed the essential of macrophages in the beneficial effects observed with PXR activation. The role of PXR in macrophages is further validated using AAV8-F4/80-Pxr shRNA-treated mice; the PXR-mediated hepatoprotection is impaired, and M2 polarization enhancement is blunted. Additionally, treatment with PXR agonists inhibited lipopolysaccharide (LPS)-induced M1 polarization and favored M2 polarization in BMDM, Raw264.7, and THP-1 cells. Further analyses revealed an interaction between PXR and p-STAT6 in vivo and in vitro. Moreover, blocking Pxr or Stat6 abolished the PXR-induced polarization shift. Collectively, macrophage PXR activation attenuated endotoxin-induced liver injury and regulated macrophage polarization through the STAT6 signaling pathway, which provided a potential therapeutic target for managing endotoxemic liver injury.
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Endotoxinas , Macrófagos , Receptor X de Pregnano , Animales , Humanos , Masculino , Ratones , Enfermedad Hepática Inducida por Sustancias y Drogas/metabolismo , Enfermedad Hepática Inducida por Sustancias y Drogas/genética , Modelos Animales de Enfermedad , Endotoxemia/metabolismo , Endotoxemia/genética , Lipopolisacáridos , Hígado/metabolismo , Macrófagos/metabolismo , Ratones Endogámicos C57BL , Receptor X de Pregnano/metabolismo , Receptor X de Pregnano/genética , Transducción de Señal , FemeninoRESUMEN
INTRODUCTION: Pregnane X receptor (PXR) is a master xenobiotic sensor that transcriptionally controls drug metabolism and disposition pathways. PXR activation by pharmaceutical drugs, natural products, environmental toxins, etc. may decrease drug efficacy and increase drug-drug interactions and drug toxicity, indicating a therapeutic value for PXR antagonists. However, PXR's functions in physiological events, such as intestinal inflammation, indicate that PXR activators may be useful in certain disease contexts. AREAS COVERED: We review the reported roles of PXR in various physiological and pathological processes including drug metabolism, cancer, inflammation, energy metabolism, and endobiotic homeostasis. We then highlight specific cellular and chemical routes that modulate PXR activity and discuss the functional consequences. Databases searched and inclusive dates: PubMed, 1 January 1980 to 10 January 2024. EXPERT OPINION: Knowledge of PXR's drug metabolism function has helped drug developers produce small molecules without PXR-mediated metabolic liabilities, and further understanding of PXR's cellular functions may offer drug development opportunities in multiple disease settings.