Search Results (24)

The nuclear receptors pregnane X receptor (PXR), constitutive androstane receptor (CAR), and farnesoid X receptor (FXR) regulate the hepatic metabolism of androstenone, a testicular steroid that accumulates in the fat of intact male pigs and causes boar taint. This study evaluated natural product-derived compounds and conventional agonists targeting these nuclear receptors for their effects on androstenone metabolism in primary hepatocytes from slaughter-weight boars, to assess their potential as treatments for boar taint. Cells were incubated with natural products, conventional agonists, or dimethyl sulfoxide (DMSO; control), then being treated with androstenone. Culture media and cells were analyzed to assess changes in androstenone metabolism and gene expression. UGT1A6 was upregulated by treatments targeting both PXR and CAR and downregulated by FXR agonists. Additionally, PGC1α and NR2F1 were downregulated by compounds targeting PXR/CAR, while FXR and NR0B2 were upregulated and HNF4α downregulated by treatments acting on FXR. The natural products diallyl sulfide (DAS) and (Z)-guggulsterone (GUG) increased overall androstenone metabolism (DAS, GUG) and the production of Phase I androstenol metabolites (DAS), but only in hepatocyte culture replicates that responded positively to these treatments. Although gene expression was similar between positive-response and negative/non-responsive replicates following treatments, negative/non-responsive replicates for several treatments had higher basal expression of UGT2B31, UGT2A1, and SIRT1 and lower basal expression of FXR, PXR, and NR0B1 compared to positive-response replicates. These findings suggest that DAS and GUG may be promising treatments for boar taint, specifically in animals with lower basal rates of androstenone metabolism and higher expression of key nuclear receptors. Full article

The rising demand for alternative solutions to diabetes mellitus has prompted significant interest in the exploration of plant-derived anti-diabetic compounds, especially within a circular economy framework that seeks sustainable and profitable reuse options. In this context, red (RSGO) and white (WGSO) grape seed oils, by-products of Sicilian vineyards, were prepared, analyzed for their fatty acid, polyphenol, carotenoid, and chlorophyll content, and evaluated for their glucose-lowering ability on HepG2 cells. Utilizing cytochemical techniques, flow cytometry, and protein blotting, we explored the effects of non-toxic oil dilutions on (i) glycogen storage, (ii) glucose consumption/uptake, (iii) GLUT-2, GLUT-4, and hepatocyte nuclear factor-1α (HNF1α) expression levels, and (iv) AMP-activated protein kinase (AMPK), insulin receptor substrate-1 (IRS-1), AKT, and PKCζ phosphorylation states, which are involved in insulin-mediated and -independent regulation of GLUT-4 membrane exposure. RGSO and WGSO, despite adopting slightly varying molecular strategies, were both proven to be effective stimulators of glucose absorption and glycogenesis. Specifically, RSGO promoted GLUT-2 and GLUT-4 up-regulation, whereas the WGSO-induced effect was associated with an increase in GLUT-4 levels alone. Moreover, the oils activated both pathways responsible for GLUT-4 translocation. Therefore, these wine-making residues have substantial potential as anti-diabetic solutions, holding promise for integration into the biomedical and food sectors. Full article

Hepatocyte nuclear factor 4α (HNF4α), a highly conserved member of the nuclear receptor superfamily of transcription factors, has been identified as a promising therapeutic candidate for colorectal adenocarcinoma (CRAC). This study was to investigate the significance of HNF4α in CRAC and mechanisms governing its function. The expression patterns and clinical relevance of HNF4α were evaluated in relation to nuclear factor kappa B (NF-κb), Yes-associated protein (YAP), and epithelial–mesenchymal transition markers. HNF4α exhibited upregulation during carcinogenesis compared to normal and precancerous lesions. The overexpression and inhibition of HNF4α were correlated with the modulation of CRAC cell migration and invasion, either promoting or suppressing these processes. Notably, levels of HNF4α were significantly diminished in metastatic and poorly differentiated CRAC relative to primary CRAC samples. Moreover, reduced HNF4α levels were associated with unfavorable prognostic factors. The inhibition of HNF4A induced a decrease in NF-κb protein levels, concomitant with an increase in YAP. Our results indicate a dual role of HNF4α in tumor progression, either as a promotor or inhibitor, depending on the pathologic condition of CRAC and the related signaling pathways. HNF4α exhibits a complex role, whereby its overexpression is linked to early carcinogenesis and reduced expression is associated with the progression and metastasis of CRAC. Full article

The cell-free aqueous extract from the coelomic fluid of Holothuria tubulosa was prepared and examined for its glucose-lowering effect on HepG2 cells in vitro. In particular, employing a combination of cytochemical, flow cytometric, PCR, and protein blot techniques, we evaluated its role on glucose internalization and storage and on the upregulation and surface translocation of the two glucose transporters GLUT-2 and -4. The changes in expression, synthesis, and/or activation of the GLUT2-related transcription factor hepatocyte nuclear factor-1 alpha (HNF1α) and the GLUT-4-translocation regulatory factors insulin receptor substrate-1 (IRS-1) and AKT were also studied. Our results showed the improved glucose response by HepG2 cells, leading to an evident increase in glucose consumption/uptake and glycogen storage upon exposure. Moreover, the extract induced molecular reprogramming involving the upregulation of (i) IRS1 gene expression, (ii) the transcription and translation levels of HNF1α, AKT, and GLUT-4, (iii) the phosphorylation level of AKT, (iv) the synthesis of GLUT-2 protein, and (v) the translocation of GLUT-2 and -4 transporters onto the plasma membrane. Cumulatively, our results suggest that the coelomic fluid extract from H. tubulosa can be taken into consideration for the development of novel treatment agents against diabetes mellitus. Full article

Gallic acid (GA) is a type of polyphenolic compound that can be found in a range of fruits, vegetables, and tea. Although it has been confirmed it improves non-alcoholic fatty liver disease (NAFLD), it is still unknown whether GA can improve the occurrence of NAFLD by increasing the low-density lipoprotein receptor (LDLR) accumulation and alleviating cholesterol metabolism disorders. Therefore, the present study explored the effect of GA on LDLR and its mechanism of action. The findings indicated that the increase in LDLR accumulation in HepG2 cells induced by GA was associated with the stimulation of the epidermal growth factor receptor–extracellular regulated protein kinase (EGFR-ERK1/2) signaling pathway. When the pathway was inhibited by EGFR mab cetuximab, it was observed that the activation of the EGFR-ERK1/2 signaling pathway induced by GA was also blocked. At the same time, the accumulation of LDLR protein and the uptake of LDL were also suppressed. Additionally, GA can also promote the accumulation of forkhead box O3 (FOXO3) and suppress the accumulation of hepatocyte nuclear factor-1α (HNF1α), leading to the inhibition of proprotein convertase subtilisin/kexin 9 (PCSK9) mRNA expression and protein accumulation. This ultimately results in increased LDLR protein accumulation and enhanced uptake of LDL in cells. In summary, the present study revealed the potential mechanism of GA’s role in ameliorating NAFLD, with a view of providing a theoretical basis for the dietary supplementation of GA. Full article

Non-alcoholic fatty liver disease (NAFLD) has emerged as a significant liver ailment attributed to factors like obesity and diabetes. While ongoing research explores treatments for NAFLD, further investigation is imperative to address this escalating health concern. NAFLD manifests as hepatic steatosis, precipitating insulin resistance and metabolic syndrome. This study aims to validate the regenerative potential of chimeric fibroblast growth factor 21 (FGF21) and Hepatocyte Growth Factor Receptor (HGFR) in NAFLD-afflicted liver cells. AML12, a murine hepatocyte cell line, was utilized to gauge the regenerative effects of chimeric FGF21/HGFR expression. Polysaccharide accumulation was affirmed through Periodic acid–Schiff (PAS) staining, while LDL uptake was microscopically observed with labeled LDL. The expression of FGF21/HGFR and NAFLD markers was analyzed by mRNA analysis with RT-PCR, which showed a decreased expression in acetyl-CoA carboxylase 1 (ACC1) and sterol regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) with increased expression of hepatocellular growth factor (HGF), hepatocellular nuclear factor 4 alpha (HNF4A), and albumin (ALB). These findings affirm the hepato-regenerative properties of chimeric FGF21/HGFR within AML12 cells, opening novel avenues for therapeutic exploration in NAFLD. Full article

MOMAST^® is a patented natural phenolic complex, rich in tyrosol (9.0 g/kg, Tyr), hydroxityrosol (43,5 g/kg, OH-Tyr), and verbascoside (5.0 g/Kg), which is obtained from the OVW by-product of the Coratina cultivar with potent direct antioxidant activity (measured by DPPH and FRAP assays, respectively). Indeed, MOMAST^® represents an innovative sustainable bioactive ingredient which has been obtained with ethical and empowering behavior by applying the principles of a circular economy. In the framework of research aimed at fostering its health-promoting activity, in this study it was clearly demonstrated that MOMAST^® treatment reduced the oxidative stress and levels of total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol, and increased the HDL levels, without changes in the triglyceride (TG) levels in Western diet (WD)-fed mice. The modulation of the plasmatic lipid profile is similar to red yeast rice (RYR) containing Monacolin K (3%). In addition, at the molecular level in liver homogenates, similarly to RYR, MOMAST^® exerts cholesterol-lowering activity through the activation of LDL receptor, whereas, unlike RYR, MOMAST^® reduces proprotein convertase subtilisin/kexin type 9 (PCSK9) protein levels via hepatic nuclear factor 1 (HNF1)-α activation. Hence, this study provides the proof of concept regarding the hypocholesterolemic activity of MOMAST, which could be successfully exploited as an active ingredient for the development of innovative and sustainable dietary supplements and functional foods. Full article

HNF4α, a member of the nuclear receptor superfamily, regulates the genes involved in lipid and glucose metabolism. The expression of the RARβ gene in the liver of HNF4α knock-out mice was higher versus wildtype controls, whereas oppositely, RARβ promoter activity was 50% reduced by the overexpression of HNF4α in HepG2 cells, and treatment with retinoic acid (RA), a major metabolite of vitamin A, increased RARβ promoter activity 15-fold. The human RARβ2 promoter contains two DR5 and one DR8 binding motifs, as RA response elements (RARE) proximal to the transcription start site. While DR5 RARE1 was previously reported to be responsive to RARs but not to other nuclear receptors, we show here that mutation in DR5 RARE2 suppresses the promoter response to HNF4α and RARα/RXRα. Mutational analysis of ligand-binding pocket amino acids shown to be critical for fatty acid (FA) binding indicated that RA may interfere with interactions of FA carboxylic acid headgroups with side chains of S190 and R235, and the aliphatic group with I355. These results could explain the partial suppression of HNF4α transcriptional activation toward gene promoters that lack RARE, including APOC3 and CYP2C9, while conversely, HNF4α may bind to RARE sequences in the promoter of the genes such as CYP26A1 and RARβ, activating these genes in the presence of RA. Thus, RA could act as either an antagonist towards HNF4α in genes lacking RAREs, or as an agonist for RARE-containing genes. Overall, RA may interfere with the function of HNF4α and deregulate HNF4α targets genes, including the genes important for lipid and glucose metabolism. Full article

Bile acid (BA) synthesis from cholesterol by hepatocytes is inhibited by inflammatory cytokines. Whether liver inflammation also affects BA side chain shortening and conjugation was investigated. In human liver cell lines (IHH, HepG2, and HepaRG), agonists of nuclear receptors including the farnesoid X receptor (FXR), liver X receptor (LXR), and peroxisome proliferator-activated receptors (PPARs) did not affect the expression of BA-related peroxisomal enzymes. In contrast, hepatocyte nuclear factor 4α (HNF4α) inhibition down-regulated acyl-CoA oxidase 2 (ACOX2). ACOX2 was repressed by fibroblast growth factor 19 (FGF19), which was prevented by extracellular signal-regulated kinase (ERK) pathway inhibition. These changes were paralleled by altered BA synthesis (HPLC-MS/MS). Cytokines able to down-regulate cholesterol-7α-hydroxylase (CYP7A1) had little effect on peroxisomal enzymes involved in BA synthesis except for ACOX2 and bile acid-CoA:amino acid N-acyltransferase (BAAT), which were down-regulated, mainly by oncostatin M (OSM). This effect was prevented by Janus kinase (JAK) inhibition, which restored BA side chain shortening and conjugation. The binding of OSM to the extracellular matrix accounted for a persistent effect after culture medium replacement. In silico analysis of four databases (n = 201) and a validation cohort (n = 90) revealed an inverse relationship between liver inflammation and ACOX2/BAAT expression which was associated with changes in HNF4α levels. In conclusion, BA side chain shortening and conjugation are inhibited by inflammatory effectors. However, other mechanisms involved in BA homeostasis counterbalance any significant impact on the serum BA profile. Full article

Background: Unwanted drug-drug interactions (DDIs), as caused by the upregulation of clinically relevant drug metabolizing enzymes and transporter proteins in intestine and liver, have the potential to threaten the therapeutic efficacy and safety of drugs. The molecular mechanism of this undesired but frequently occurring scenario of polypharmacy is based on the activation of nuclear receptors such as the pregnane X receptor (PXR) or the constitutive androstane receptor (CAR) by perpetrator agents such as rifampin, phenytoin or St. John’s wort. However, the expression pattern of nuclear receptors in human intestine and liver remains uncertain, which makes it difficult to predict the extent of potential DDIs. Thus, it was the aim of this study to characterize the gene expression and protein abundance of clinically relevant nuclear receptors, i.e., the aryl hydrocarbon receptor (AhR), CAR, farnesoid X receptor (FXR), glucocorticoid receptor (GR), hepatocyte nuclear factor 4 alpha (HNF4α), PXR and small heterodimer partner (SHP), in the aforementioned organs. Methods: Gene expression analysis was performed by quantitative real-time PCR of jejunal, ileal, colonic and liver samples from eight human subjects. In parallel, a targeted proteomic method was developed and validated in order to determine the respective protein amounts of nuclear receptors in human intestinal and liver samples. The LC-MS/MS method was validated according to the current bioanalytical guidelines and met the criteria regarding linearity (0.1–50 nmol/L), within-day and between-day accuracy and precision, as well as the stability criteria. Results: The developed method was successfully validated and applied to determine the abundance of nuclear receptors in human intestinal and liver samples. Gene expression and protein abundance data demonstrated marked differences in human intestine and liver. On the protein level, only AhR and HNF4α could be detected in gut and liver, which corresponds to their highest gene expression. In transfected cell lines, PXR and CAR could be quantified. Conclusions: The substantially different expression pattern of nuclear receptors in human intestinal and liver tissue may explain the different extent of unwanted DDIs in the dependence on the administration route of drugs. Full article

Hempseed (Cannabis sativa) protein is an important source of bioactive peptides. H3 (IGFLIIWV), a transepithelial transported intestinal peptide obtained from the hydrolysis of hempseed protein with pepsin, carries out antioxidant and anti-inflammatory activities in HepG2 cells. In this study, the main aim was to assess its hypocholesterolemic effects at a cellular level and the mechanisms behind this health-promoting activity. The results showed that peptide H3 inhibited the 3-hydroxy-3-methylglutaryl co-enzyme A reductase (HMGCoAR) activity in vitro in a dose-dependent manner with an IC₅₀ value of 59 μM. Furthermore, the activation of the sterol regulatory element binding proteins (SREBP)-2 transcription factor, followed by the increase of low-density lipoprotein (LDL) receptor (LDLR) protein levels, was observed in human hepatic HepG2 cells treated with peptide H3 at 25 µM. Meanwhile, peptide H3 regulated the intracellular HMGCoAR activity through the increase of its phosphorylation by the activation of AMP-activated protein kinase (AMPK)-pathways. Consequently, the augmentation of the LDLR localized on the cellular membranes led to the improved ability of HepG2 cells to uptake extracellular LDL with a positive effect on cholesterol levels. Unlike the complete hempseed hydrolysate (HP), peptide H3 can reduce the proprotein convertase subtilisin/kexin 9 (PCSK9) protein levels and its secretion in the extracellular environment via the decrease of hepatic nuclear factor 1-α (HNF1-α). Considering all these evidences, H3 may represent a new bioactive peptide to be used for the development of dietary supplements and/or peptidomimetics for cardiovascular disease (CVD) prevention. Full article

The anti-hepatitis B virus (HBV) efficacy of baicalin (BA) is mediated by HBV-related hepatocyte nuclear factors (HNFs). However, this efficacy is severely limited by the low bioavailability of BA. Therefore, a novel liver-targeted BA liposome was constructed to promote the bioavailability and antiviral ability of BA. The results showed that apolipoprotein A1 (ApoA1)–modified liposomes (BAA1) significantly enhanced BA’s cellular uptake and specific distribution in the liver. Furthermore, the substantial inhibitory effects of BAA1 on HBsAg, HBeAg, HBV RNA, and HBV DNA were assessed in HB-infected cells and mice. Western blotting, co-immunoprecipitation, and transcriptomics analysis further revealed that the enhanced anti-HBV efficacy of BAA1 was attributed to the interaction between hepatocyte nuclear factors (HNFs) and estrogen receptors (ERs). Based on the findings, we propose that the ApoA1-modified liposomes aid BA in inhibiting HBV transcription and replication by augmenting its bioavailability and the HNFs–ERs axis. Full article

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor known for mediating the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. Although the canonical mechanism of AhR activation involves heterodimerization with the aryl hydrocarbon receptor nuclear translocator, other transcriptional regulators that interact with AhR have been identified. Enrichment analysis of motifs in AhR-bound genomic regions implicated co-operation with COUP transcription factor (COUP-TF) and hepatocyte nuclear factor 4 (HNF4). The present study investigated AhR, HNF4α and COUP-TFII genomic binding and effects on gene expression associated with liver-specific function and cell differentiation in response to TCDD. Hepatic ChIPseq data from male C57BL/6 mice at 2 h after oral gavage with 30 µg/kg TCDD were integrated with bulk RNA-sequencing (RNAseq) time-course (2–72 h) and dose–response (0.01–30 µg/kg) datasets to assess putative AhR, HNF4α and COUP-TFII interactions associated with differential gene expression. Functional enrichment analysis of differentially expressed genes (DEGs) identified differential binding enrichment for AhR, COUP-TFII, and HNF4α to regions within liver-specific genes, suggesting intersections associated with the loss of liver-specific functions and hepatocyte differentiation. Analysis found that the repression of liver-specific, HNF4α target and hepatocyte differentiation genes, involved increased AhR and HNF4α binding with decreased COUP-TFII binding. Collectively, these results suggested TCDD-elicited loss of liver-specific functions and markers of hepatocyte differentiation involved interactions between AhR, COUP-TFII and HNF4α. Full article

MOMAST^® is a patented phenolic complex derived from the olive oil vegetation water, a by-product of the olive oil supply chain, in which hydroxytyrosol (OH-Tyr) and tyrosol (Tyr) and verbascoside are the main compounds. This study was aimed at investigating its hypocholesterolemic effect by assessing the ability to modulate the low-density lipoprotein (LDL) receptor (LDLR)/sterol regulatory element-binding protein 2 (SREBP-2), and proprotein convertase subtilisin/kexin type 9 (PCSK9) pathways. MOMAST^® inhibits the in vitro activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGC_OAR) with a dose-response trend. After the treatment of HepG2 cells, MOMAST^® increases the SREBP-2, LDLR, and HMGCoAR protein levels leading, from a functional point of view to an improved ability of hepatic cells to up-take LDL from the extracellular environment with a final cholesterol-lowering effect. Furthermore, MOMAST^® decreased the PCSK9 protein levels and its secretion in the extracellular environment, presumably via the reduction of the hepatic nuclear factor 1-α (HNF1-α). The experiments were performed in parallel, using pravastatin as a reference compound. Results demonstrated that MOMAST^® may be exploited as a new ingredient for the development of functional foods and/or nutraceuticals for cardiovascular disease prevention. Full article

High-fat diets induced abnormal lipid accumulation in the liver of cultured fish that caused body damage and diseases. The purpose of this research was to investigate the role and mechanism of farnesoid X receptor (FXR) in regulating lipid metabolism and to determine how high-fat diets affect FXR expression in large yellow croakers. The results showed that ligand-meditated FXR-activation could prevent abnormal lipid accumulation in the liver and hepatocytes of large yellow croakers. FXR activation increased the expression of lipid catabolism-related genes while decreasing the expression of lipogenesis-related genes. Further investigation found that the promoter activity of proliferator-activated receptor α (PPARα) could be increased by croaker FXR. Through the influence of SHP on LXR, FXR indirectly decreased the promoter activity of sterol regulatory element binding protein 1 (SREBP1) in large yellow croakers. Furthermore, the findings revealed that endoplasmic reticulum (ER)-stress-induced-activation of JNK and P38 MAPK participated in the reduction of FXR induced by high-fat diets. Then, hepatocyte nuclear factor 1α (HNF1α) was confirmed to be an FXR regulator in large yellow croaker, and it was reduced by high-fat diets and ER stress. In addition, co-expression of c-Jun with HNF1α inhibited the effect of HNF1α on FXR promoter, and suppression of P38 MAPK could relieve the HNF1α expression reduction caused by ER stress activation. In summary, the present study showed that FXR mediated lipid metabolism can prevent abnormal lipid accumulation through regulating PPARα and SREBP1 in large yellow croakers, while high-fat diets can suppress FXR expression by ER stress mediated-activation of JNK and P38 MAPK pathways. This research could benefit the study of FXR functions in vertebrate evolution and the development of therapy or preventative methods for nutrition-related disorders. Full article