scholarly journals Dietary Polyphenols Increase Paraoxonase 1 Gene Expression by an Aryl Hydrocarbon Receptor-Dependent Mechanism

2004 ◽  
Vol 24 (12) ◽  
pp. 5209-5222 ◽  
Author(s):  
Cédric Gouédard ◽  
Robert Barouki ◽  
Yannick Morel
Keyword(s):  
Gene Expression ◽  
Aryl Hydrocarbon Receptor ◽  
Hepatoma Cell ◽  
Paraoxonase 1 ◽  
Hepatoma Cell Line ◽  
Target Sequence ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Dietary Polyphenols ◽  
Aryl Hydrocarbon

ABSTRACT Human paraoxonase 1 (PON-1) is a serum high-density lipoprotein-associated enzyme mainly secreted by the liver. It has endogenous and exogenous substrates and displays protective properties with respect to cardiovascular disease and organophosphate intoxication. In the HuH7 human hepatoma cell line, PON-1 activity and mRNA levels were increased by dietary polyphenolic compounds such as quercetin but also by toxic ligands of the aryl hydrocarbon receptor (AhR) such as 3-methylcholanthrene (3-MC). However, the 2,3,7,8-tetrachlorobenzo(p)dioxin (TCDD) was a poor inducer. Transient and stable transfection assays indicated that these compounds increased the PON-1 gene promoter activity in an AhR-dependent manner, since their effect was inhibited by 7-keto-cholesterol and AhR-directed short interfering RNA. Deletions and mutations studies showed that a xenobiotic responsive element (XRE)-like sequence within the PON-1 promoter mediated the effect of 3-MC and quercetin. In contrast with consensus XREs from the cytochrome P450 1A1 gene, the PON-1 XRE-like element mediated preferentially the effect of quercetin compared to the results seen with TCDD. Furthermore, AhR binding to this element was preferentially activated by quercetin. These observations provide a molecular mechanism for the regulation of the cardioprotective enzyme PON-1 by polyphenols. They suggest also that AhR ligands may differentially regulate gene expression depending on the DNA target sequence.

scholarly journals Aryl Hydrocarbon Receptor Activation by TCDD Modulates Expression of Extracellular Matrix Remodeling Genes during Experimental Liver Fibrosis

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Cheri L. Lamb ◽  
Giovan N. Cholico ◽  
Daniel E. Perkins ◽  
Michael T. Fewkes ◽  
Julia Thom Oxford ◽  
...  
Keyword(s):  
Gene Expression ◽  
Extracellular Matrix ◽  
Liver Injury ◽  
Aryl Hydrocarbon Receptor ◽  
Receptor Activation ◽  
Matrix Remodeling ◽  
Mrna Levels ◽  
Gelatinase Activity ◽  
Ecm Remodeling ◽  
Aryl Hydrocarbon

The aryl hydrocarbon receptor (AhR) is a soluble, ligand-activated transcription factor that mediates the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Increasing evidence implicates the AhR in regulating extracellular matrix (ECM) homeostasis. We recently reported that TCDD increased necroinflammation and myofibroblast activation during liver injury elicited by carbon tetrachloride (CCl4). However, TCDD did not increase collagen deposition or exacerbate fibrosis in CCl4-treated mice, which raises the possibility that TCDD may enhance ECM turnover. The goal of this study was to determine how TCDD impacts ECM remodeling gene expression in the liver. Male C57BL/6 mice were treated for 8 weeks with 0.5 mL/kg CCl4, and TCDD (20 μg/kg) was administered during the last two weeks. Results indicate that TCDD increased mRNA levels of procollagen types I, III, IV, and VI and the collagen processing molecules HSP47 and lysyl oxidase. TCDD also increased gelatinase activity and mRNA levels of matrix metalloproteinase- (MMP-) 3, MMP-8, MMP-9, and MMP-13. Furthermore, TCDD modulated expression of genes in the plasminogen activator/plasmin system, which regulates MMP activation, and it also increased TIMP1 gene expression. These findings support the notion that AhR activation by TCDD dysregulates ECM remodeling gene expression and may facilitate ECM metabolism despite increased liver injury.

Sensing Iron: Reciprocal Regulation of Hepcidin mRNA by Soluble and Cell-Associated Hemojuvelin.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 512-512
Author(s):  
Lan Lin ◽  
Y. Paul Goldberg ◽  
Tomas Ganz
Keyword(s):  
Iron Homeostasis ◽  
Genomic Sequence ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Human Hepatoma Cell ◽  
Hepcidin Expression ◽  
Juvenile Hemochromatosis ◽  
Hepcidin Mrna

Abstract Human genetic studies identified HJV (also called HFE2) as the major cause for juvenile hemochromatosis (JH). Patients with HJV hemochromatosis have low urinary levels of hepcidin, the principal iron-regulatory hormone secreted by the liver. We attempted to establish the specific roles of HJV in iron metabolism, especially its relationship with hepcidin. Translation of the genomic sequence indicated a C-terminal GPI anchor for the protein product of HJV, hemojuvelin. This suggested that hemojuvelin may have either a soluble or a cell-associated form. In human hepatoma cell line Hep3B, knockdown of cellular HJV by siRNA decreased hepcidin expression, independently of the IL-6 pathway. Intriguingly, the addition of recombinant soluble hemojuvelin (rs-hemojuvelin) also suppressed hepcidin expression in primary human hepatocytes, in a log-linear dose-dependent manner, suggesting competition between soluble and cell-associated forms of hemojuvelin. Soluble hemojuvelin was found in human sera at concentrations similar to those required to suppress hepcidin mRNA in vitro. In cells engineered to express hemojuvelin, soluble hemojuvelin release was progressively inhibited by increasing iron or holotransferrin concentrations. Our study suggests that soluble and cell-associated hemojuvelin reciprocally regulate hepcidin mRNA levels, and that hemojuvelin may serve as a molecular messenger for iron homeostasis. Even in hepatocytes stimulated with IL-6, we observed strong suppression of hepcidin mRNA by rs-hemojuvelin. If rs-hemojuvelin or its active fragments also suppress hepcidin production in vivo, they could be used to alleviate anemia of inflammation.

scholarly journals Analysis of gene expression in Lassa virus-infected HuH-7 cells

2007 ◽  
Vol 88 (5) ◽  
pp. 1568-1575 ◽  
Author(s):  
Stefanie Müller ◽  
Robert Geffers ◽  
Stephan Günther
Keyword(s):  
Gene Expression ◽  
Virus Infection ◽  
Real Time ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Lassa Virus ◽  
Mrna Levels ◽  
Rt Pcr ◽  
Array Data ◽  
U133a Array

The pathogenesis of Lassa fever is poorly understood. As the liver is a major target organ of Lassa virus, gene expression in Lassa virus-infected HuH-7 cells, a differentiated human hepatoma cell line, was studied. Cellular mRNA levels were measured at the late phase of acute infection, when virtually all cells expressed large amounts of nucleoprotein, and virus RNA concentration had reached >108 copies (ml supernatant)−1. Two types of transcription array were used: cDNA-based macroarrays with a set of 3500 genes (Atlas Human 1.2 arrays; Clontech) and oligonucleotide-based microarrays covering 18 400 transcripts (Human Genome U133A array; Affymetrix). Data analysis was based on statistical frameworks controlling the false-discovery rate. Atlas array data were considered relevant if they could be verified by U133A array or real-time RT-PCR. According to these criteria, there was no evidence for true changes in gene expression. Considering the precision of the U133A array and the number of replicates tested, potential expression changes due to Lassa virus infection are probably smaller than twofold. To substantiate the array data, beta interferon (IFN-β) gene expression was studied longitudinally in Lassa virus-infected HuH-7 and FRhK-4 cells by using real-time RT-PCR. IFN-β mRNA levels increased only twofold upon Lassa virus infection, although there was no evidence that the virus inhibited poly(I : C)-induced IFN-β gene expression. In conclusion, Lassa virus interferes only minimally with gene expression in HuH-7 cells and poorly induces IFN-β gene transcription.

Hypoxia-inducible erythropoietin gene expression in human neuroblastoma cells

Blood ◽  
2002 ◽  
Vol 100 (7) ◽  
pp. 2623-2628 ◽  
Author(s):  
Ineke Stolze ◽  
Utta Berchner-Pfannschmidt ◽  
Patricia Freitag ◽  
Christoph Wotzlaw ◽  
Jochen Rössler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Western Blot ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Dependent Manner ◽  
Independent Manner ◽  
Human Neuroblastoma ◽  
Α Subunit

Two human neuroblastoma (NB) cell lines, SH-SY5Y and Kelly, were found to express the gene for erythropoietin (EPO) in an oxygen (O2)-dependent manner. However, NB cells had maximal production of EPO with lower partial pressure of O2 values than the well-characterized hepatoma cell line HepG2. This maximal EPO expression was preceded by accumulation of the O2-sensitive α subunit of the heterodimeric transcription-factor complex hypoxia-inducible factor 1 (HIF-1). Western blot analysis revealed that the amount of the β subunit of HIF-1, identical to aryl hydrocarbon receptor nuclear translocator 1 (ARNT1), and the homolog ARNT2 increased in nuclear extracts from SH-SY5Y cells exposed to anoxia. In neuronal cells, ARNT1 and ARNT2 can form a heterodimer with HIF-1α, generating a functional HIF-1 complex. Using the hypoxia response element of the human EPO enhancer, we conducted electrophoretic mobility shift assays that showed accumulation and binding of HIF-1 complexes containing both ARNT1 and ARNT2 in NB cells. In addition to the HIF-1 complex, hepatocyte nuclear factor 4α (HNF4α) was found to be indispensable for hypoxia-induced EPO gene expression in hepatoma cells. Western blot analysis and polymerase chain reaction assessment showed that NB cells express neither HNF4α nor the splicing variant HNF4α7 and thus express EPO in an HNF4α-independent manner. Together, SH-SY5Y and Kelly cells may provide a new in vitro model for studying the mechanism of tissue-specific, hypoxia-inducible EPO gene expression.

scholarly journals Ultrasensitivity dynamics of diverse aryl hydrocarbon receptor modulators in a hepatoma cell line

2018 ◽  
Vol 93 (3) ◽  
pp. 635-647 ◽  
Author(s):  
Timothy E. Hoffman ◽  
Evan R. Acerbo ◽  
Kasimir F. Carranza ◽  
Vincenzo S. Gilberto ◽  
Lyle E. Wallis ◽  
...  
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Cell Line ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Aryl Hydrocarbon ◽  
Receptor Modulators

scholarly journals Transcriptional activation of heat shock protein 27 gene expression by 17beta-estradiol and modulation by antiestrogens and aryl hydrocarbon receptor agonists

2001 ◽  
Vol 26 (1) ◽  
pp. 31-42 ◽  
Author(s):  
W Porter ◽  
F Wang ◽  
R Duan ◽  
C Qin ◽  
E Castro-Rivera ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Aryl Hydrocarbon Receptor ◽  
Transcriptional Activation ◽  
Heat Shock Protein 27 ◽  
Mrna Levels ◽  
Aryl Hydrocarbon ◽  
Hsp 27 ◽  
Mcf 7

Heat shock protein 27 (Hsp 27) is expressed in mammary tumors and may play a role in tumor growth and response to anti-neoplastic drug therapy. 17beta-Estradiol (E2) induces Hsp 27 mRNA levels in MCF-7 human breast cancer cells, and we have investigated the comparative inhibitory mechanisms using the aryl hydrocarbon receptor (AhR) agonist, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the direct-acting antiestrogen ICI 164,384. TCDD inhibited E2-induced Hsp 27 gene expression and analysis of the Hsp 27 gene promoter showed that the inhibitory response was associated with AhR interactions with a pentanucleotide motif at -3 to +2 in the promoter that corresponded to the core sequence of a dioxin responsive element. In contrast, ICI 164,384 induced Hsp 27 gene expression and reporter gene activity in MCF-7 cells and this represents one of the few examples of the estrogen receptor-alpha (ERalpha) agonist activity of the 'pure' antiestrogen ICI 164,384.

Identifying target genes of the aryl hydrocarbon receptor nuclear translocator (Arnt) using DNA microarray analysis

2006 ◽  
Vol 387 (9) ◽  
pp. 1215-1218 ◽  
Author(s):  
Feng Wang ◽  
Shengli Shi ◽  
Ruixue Zhang ◽  
Oliver Hankinson
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Microarray Analysis ◽  
Dna Microarray ◽  
Target Genes ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Cysteine Proteinase Inhibitor ◽  
Dna Microarray Analysis ◽  
Aryl Hydrocarbon ◽  
Upregulated Genes

Abstract The aryl hydrocarbon receptor nuclear translocator (Arnt) is a basic helix-loop-helix (bHLH) protein that also contains a Per-Arnt-Sim (PAS) domain. In addition to forming heterodimers with many other bHLH-PAS proteins, including the aryl hydrocarbon receptor (AhR) and hypoxia-inducible factors 1α, 2α and 3α, Arnt can also form homodimers when expressed from its cDNA in vitro or in vivo. However, target genes of the Arnt/Arnt homodimer remain to be identified. In this study, we have elucidated the profile of genes responsive to the reintroduction of Arnt expression in an Arnt-deficient mouse hepatoma cell line (c4), using DNA microarray analysis. The expression of 27 genes was upregulated by 1.5-fold or more in c4 cells infected with a retroviral vector expressing mouse Arnt, while no genes were found to be downregulated. Among the upregulated genes, BCL2/adenovirus E1B 19 kDa-interacting protein 1 (NIP3), serine (or cysteine) proteinase inhibitor, clade E, member 1 (PAI1), and N-myc downstream regulated-like (NDR1), were confirmed to be induced by Arnt using real-time PCR. We also found that the 5′ promoter region of 15 out of 20 upregulated genes contain the type 2 E-box 5′-CACGTG-3′ Arnt/Arnt binding sequence, consistent with the notion that they represent target genes for Arnt.

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