scholarly journals The Connection of Azole Fungicides with Xeno-Sensing Nuclear Receptors, Drug Metabolism and Hepatotoxicity

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1192 ◽  
Author(s):  
Philip Marx-Stoelting ◽  
Constanze Knebel ◽  
Albert Braeuning
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Liver Tumors ◽  
Current Knowledge ◽  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Receptor Activation ◽  
Azole Fungicides

Azole fungicides, especially triazole compounds, are widely used in agriculture and as pharmaceuticals. For a considerable number of agricultural azole fungicides, the liver has been identified as the main target organ of toxicity. A number of previous studies points towards an important role of nuclear receptors such as the constitutive androstane receptor (CAR), the pregnane-X-receptor (PXR), or the aryl hydrocarbon receptor (AHR), within the molecular pathways leading to hepatotoxicity of these compounds. Nuclear receptor-mediated hepatic effects may comprise rather adaptive changes such as the induction of drug-metabolizing enzymes, to hepatocellular hypertrophy, histopathologically detectable fatty acid changes, proliferation of hepatocytes, and the promotion of liver tumors. Here, we present a comprehensive review of the current knowledge of the interaction of major agricultural azole-class fungicides with the three nuclear receptors CAR, PXR, and AHR in vivo and in vitro. Nuclear receptor activation profiles of the azoles are presented and related to histopathological findings from classic toxicity studies. Important issues such as species differences and multi-receptor agonism and the consequences for data interpretation and risk assessment are discussed.

scholarly journals Nuclear receptor phosphorylation in xenobiotic signal transduction

2020 ◽  
Vol 295 (45) ◽  
pp. 15210-15225 ◽  
Author(s):  
Masahiko Negishi ◽  
Kaoru Kobayashi ◽  
Tsutomu Sakuma ◽  
Tatsuya Sueyoshi
Keyword(s):  
Dna Binding ◽  
Cell Signaling ◽  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Pregnane X Receptor ◽  
Receptor Activation ◽  
Binding Domain ◽  
Activation Mechanism ◽  
Dna Binding Domain ◽  
Phosphorylation Motif

Nuclear pregnane X receptor (PXR, NR1I2) and constitutive active/androstane receptor (CAR, NR1I3) are nuclear receptors characterized in 1998 by their capability to respond to xenobiotics and activate cytochrome P450 (CYP) genes. An anti-epileptic drug, phenobarbital (PB), activates CAR and its target CYP2B genes, whereas PXR is activated by drugs such as rifampicin and statins for the CYP3A genes. Inevitably, both nuclear receptors have been investigated as ligand-activated nuclear receptors by identifying and characterizing xenobiotics and therapeutics that directly bind CAR and/or PXR to activate them. However, PB, which does not bind CAR directly, presented an alternative research avenue for an indirect ligand-mediated nuclear receptor activation mechanism: phosphorylation-mediated signal regulation. This review summarizes phosphorylation-based mechanisms utilized by xenobiotics to elicit cell signaling. First, the review presents how PB activates CAR (and other nuclear receptors) through a conserved phosphorylation motif located between two zinc fingers within its DNA-binding domain. PB-regulated phosphorylation at this motif enables nuclear receptors to form communication networks, integrating their functions. Next, the review discusses xenobiotic-induced PXR activation in the absence of the conserved DNA-binding domain phosphorylation motif. In this case, phosphorylation occurs at a motif located within the ligand-binding domain to transduce cell signaling that regulates hepatic energy metabolism. Finally, the review delves into the implications of xenobiotic-induced signaling through phosphorylation in disease development and progression.

scholarly journals The DRIP Complex and SRC-1/p160 Coactivators Share Similar Nuclear Receptor Binding Determinants but Constitute Functionally Distinct Complexes

2000 ◽  
Vol 20 (8) ◽  
pp. 2718-2726 ◽  
Author(s):  
Christophe Rachez ◽  
Matthew Gamble ◽  
Chao-Pei Betty Chang ◽  
G. Brandon Atkins ◽  
Mitchell A. Lazar ◽  
...  
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Receptor Binding ◽  
Transcriptional Activation ◽  
Thyroid Hormone Receptor ◽  
Nuclear Receptor Coactivators ◽  
Nuclear Extracts ◽  
Sequence Requirements

ABSTRACT Transcriptional activation requires both access to DNA assembled as chromatin and functional contact with components of the basal transcription machinery. Using the hormone-bound vitamin D3receptor (VDR) ligand binding domain (LBD) as an affinity matrix, we previously identified a novel multisubunit coactivator complex, DRIP (VDR-interacting proteins), required for transcriptional activation by nuclear receptors and several other transcription factors. In this report, we characterize the nuclear receptor binding features of DRIP205, a key subunit of the DRIP complex, that interacts directly with VDR and thyroid hormone receptor in response to ligand and anchors the other DRIP subunits to the nuclear receptor LBD. In common with other nuclear receptor coactivators, DRIP205 interaction occurs through one of two LXXLL motifs and requires the receptor's AF-2 subdomain. Although the second motif of DRIP205 is required only for VDR binding in vitro, both motifs are used in the context of an retinoid X receptor-VDR heterodimer on DNA and in transactivation in vivo. We demonstrate that both endogenous p160 coactivators and DRIP complexes bind to the VDR LBD from nuclear extracts through similar sequence requirements, but they do so as distinct complexes. Moreover, in contrast to the p160 family of coactivators, the DRIP complex is devoid of any histone acetyltransferase activity. The results demonstrate that different coactivator complexes with distinct functions bind to the same transactivation region of nuclear receptors, suggesting that they are both required for transcription activation by nuclear receptors.

Combining In Vivo and Organotypic In Vitro Approaches to Assess the Human Relevance of Basimglurant (RG7090), a Potential CAR Activator

2020 ◽  
Vol 176 (2) ◽  
pp. 329-342
Author(s):  
Ramona Nudischer ◽  
Kasper Renggli ◽  
Cristina Bertinetti-Lapatki ◽  
Jean-Christophe Hoflack ◽  
Nicholas Flint ◽  
...  
Keyword(s):  
Antisense Oligonucleotides ◽  
Human Liver ◽  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Mrna Induction ◽  
Primary Mouse ◽  
Downstream Processes ◽  
Foci Of Altered Hepatocytes

Abstract Basimglurant (RG7090), a small molecule under development to treat certain forms of depression, demonstrated foci of altered hepatocytes in a long-term rodent-toxicity study. Additional evidence pointed toward the activation of the constitutive androstane receptor (CAR), an established promoter of nongenotoxic and rodent-specific hepatic tumors. This mode of action and the potential human relevance was explored in vivo using rodent and cynomolgus monkey models and in vitro using murine and human liver spheroids. Wild type (WT) and CAR/pregnane X receptor (PXR) knockout mice (CAR/PXR KO) were exposed to RG7090 for 8 consecutive days. Analysis of liver lysates revealed induction of Cyp2b mRNA and enzyme activity, a known activation marker of CAR, in WT but not in CAR/PXR KO animals. A series of proliferative genes were upregulated in WT mice only, and immunohistochemistry data showed increased cell proliferation exclusively in WT mice. In addition, primary mouse liver spheroids were challenged with RG7090 in the presence or absence of modified antisense oligonucleotides inhibiting CAR and/or PXR mRNA, showing a concentration-dependent Cyp2b mRNA induction only if CAR was not repressed. On the contrary, neither human liver spheroids nor cynomolgus monkeys exposed to RG7090 triggered CYP2B mRNA upregulation. Our data suggested RG7090 to be a rodent-specific CAR activator, and that CAR activation and its downstream processes were involved in the foci of altered hepatocytes formation detected in vivo. Furthermore, we demonstrated the potential of a new in vitro approach using liver spheroids and antisense oligonucleotides for CAR knockdown experiments, which could eventually replace in vivo investigations using CAR/PXR KO mice.

scholarly journals Regulation of CAR and PXR Expression in Health and Disease

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2395
Author(s):  
Martine Daujat-Chavanieu ◽  
Sabine Gerbal-Chaloin
Keyword(s):  
Transcription Factors ◽  
Nuclear Receptor ◽  
Current Knowledge ◽  
Constitutive Androstane Receptor ◽  
Adult Life ◽  
Pregnane X Receptor ◽  
Regulatory Mechanisms ◽  
Nuclear Receptor Superfamily ◽  
Pathological Conditions ◽  
Health And Disease

Pregnane X receptor (PXR, NR1I2) and constitutive androstane receptor (CAR, NR1I3) are members of the nuclear receptor superfamily that mainly act as ligand-activated transcription factors. Their functions have long been associated with the regulation of drug metabolism and disposition, and it is now well established that they are implicated in physiological and pathological conditions. Considerable efforts have been made to understand the regulation of their activity by their cognate ligand; however, additional regulatory mechanisms, among which the regulation of their expression, modulate their pleiotropic effects. This review summarizes the current knowledge on CAR and PXR expression during development and adult life; tissue distribution; spatial, temporal, and metabolic regulations; as well as in pathological situations, including chronic diseases and cancers. The expression of CAR and PXR is modulated by complex regulatory mechanisms that involve the interplay of transcription factors and also post-transcriptional and epigenetic modifications. Moreover, many environmental stimuli affect CAR and PXR expression through mechanisms that have not been elucidated.

scholarly journals Use of Differential Scanning Fluorimetry as a High-Throughput Assay to Identify Nuclear Receptor Ligands

2012 ◽  
Vol 10 (1) ◽  
pp. nrs.10002 ◽  
Author(s):  
Kara DeSantis ◽  
Aaron Reed ◽  
Raneen Rahhal ◽  
Jeff Reinking
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
High Throughput ◽  
Initial Step ◽  
Estrogen Receptor Α ◽  
Chemical Library ◽  
Differential Scanning Fluorimetry ◽  
Nuclear Receptor Ligands

Identification of ligands that interact with nuclear receptors is both a major biological problem and an important initial step in drug discovery. Several in vitro and in vivo techniques are commonly used to screen ligand candidates against nuclear receptors; however, none of the current assays allow screening without modification of either the protein and/or the ligand in a high-throughput fashion. Differential scanning fluorimetry (DSF) allows unmodified potential ligands to be screened as 10μL reactions in 96-well format against partially purified protein, revealing specific interactors. As a proof of principle, we used a commercially-available nuclear receptor ligand candidate chemical library to identify interactors of the human estrogen receptor α ligand binding domain (ERα LBD). Compounds that interact specifically with ERα LBD stabilize the protein and result in an elevation of the thermal denaturation point, as monitored by the environmentally-sensitive dye SYPRO orange. We successfully identified all three compounds in the library that have previously been identified to interact with ERα, with no false positive results.

scholarly journals Modulation of Transcriptional Activation and Coactivator Interaction by a Splicing Variation in the F Domain of Nuclear Receptor Hepatocyte Nuclear Factor 4α1

1999 ◽  
Vol 19 (10) ◽  
pp. 6509-6522 ◽  
Author(s):  
Frances M. Sladek ◽  
Michael D. Ruse ◽  
Luviminda Nepomuceno ◽  
Shih-Ming Huang ◽  
Michael R. Stallcup
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Transcriptional Activation ◽  
Regulatory Region ◽  
Physical Contact ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Splicing Variants

ABSTRACT Transcription factors, such as nuclear receptors, often exist in various forms that are generated by highly conserved splicing events. Whereas the functional significance of these splicing variants is often not known, it is known that nuclear receptors activate transcription through interaction with coactivators. The parameters, other than ligands, that might modulate those interactions, however, are not well characterized, nor is the role of splicing variants. In this study, transient transfection, yeast two-hybrid, and GST pulldown assays are used to show not only that nuclear receptor hepatocyte nuclear factor 4 α1 (HNF4α1, NR2A1) interacts with GRIP1, and other coactivators, in the absence of ligand but also that the uncommonly large F domain in the C terminus of the receptor inhibits that interaction. In vitro, the F domain was found to obscure an AF-2-independent binding site for GRIP1 that did not map to nuclear receptor boxes II or III. The results also show that a natural splicing variant containing a 10-amino-acid insert in the middle of the F domain (HNF4α2) abrogates that inhibition in vivo and in vitro. A series of protease digestion assays indicates that there may be structural differences between HNF4α1 and HNF4α2 in the F domain as well as in the ligand binding domain (LBD). The data also suggest that there is a direct physical contact between the F domain and the LBD of HNF4α1 and -α2 and that that contact is different in the HNF4α1 and HNF4α2 isoforms. Finally, we propose a model in which the F domain of HNF4α1 acts as a negative regulatory region for transactivation and in which the α2 insert ameliorates the negative effect of the F domain. A conserved repressor sequence in the F domains of HNF4α1 and -α2 suggests that this model may be relevant to other nuclear receptors as well.

scholarly journals A novel approach to investigate the subcellular distribution of nuclear receptors in vivo

2009 ◽  
Vol 7 (1) ◽  
pp. nrs.07004 ◽  
Author(s):  
Marko Matic ◽  
Sarah Nakhel ◽  
Anne M. Lehnert ◽  
Patsie Polly ◽  
Stephen J. Clarke ◽  
...  
Keyword(s):  
Nuclear Receptors ◽  
Nuclear Receptor ◽  
Subcellular Distribution ◽  
Mammalian Cells ◽  
Pregnane X Receptor ◽  
Subcellular Localisation ◽  
Regulatory Processes ◽  
Cellular Expression ◽  
Novel Approach

Subcellular compartmentalisation and the intracellular movement of nuclear receptors are major regulatory steps in executing their transcriptional function. Though significant progress has been made in understanding these regulatory processes in cultured mammalian cells, such results have rarely been confirmed within cells of a living mammal. This article describes a simple, time-efficient approach to study the nuclear versus cytoplasmic accumulation of nuclear receptors and the regions of nuclear receptor proteins that govern subcellular trafficking within hepatocytes of live mice. Pregnane X receptor, a xenobiotic-activated member of the nuclear receptor family, was used to exemplify the approach. Using dual-labeled wild-type and mutant PXR expression constructs, we outline their in vivo delivery, simultaneous cellular expression, visualization and categorical classification within hepatocytes of live mice. Using this approach, we identified three mutants that had an altered subcellular distribution in the presence and absence of a PXR ligand. This novel in vivo method complements the current cell culture-based experimental systems in protein subcellular localisation studies.

scholarly journals In Vivo and In Vitro Characterization of a First-in-Class Novel Azole Analog That Targets Pregnane X Receptor Activation

2011 ◽  
Vol 80 (1) ◽  
pp. 124-135 ◽  
Author(s):  
Madhukumar Venkatesh ◽  
Hongwei Wang ◽  
Julie Cayer ◽  
Melissa Leroux ◽  
Dany Salvail ◽  
...  
Keyword(s):  
Pregnane X Receptor ◽  
Receptor Activation ◽  
In Vitro Characterization

Modulation of Matrix Metalloproteinases by Plant-Derived Products

2020 ◽  
Vol 20 ◽  
Author(s):  
Nur Najmi Mohamad Anuar ◽  
Nurul Iman Natasya Zulkafali ◽  
Azizah Ugusman
Keyword(s):  
Clinical Trials ◽  
Natural Products ◽  
Matrix Metalloproteinases ◽  
Animal Studies ◽  
Current Knowledge ◽  
In Vitro Models ◽  
In Vivo Studies ◽  
Extracellular Matrix Components

: Matrix metalloproteinases (MMPs) are a group of zinc-dependent metallo-endopeptidase that are responsible towards the degradation, repair and remodelling of extracellular matrix components. MMPs play an important role in maintaining a normal physiological function and preventing diseases such as cancer and cardiovascular diseases. Natural products derived from plants have been used as traditional medicine for centuries. Its active compounds, such as catechin, resveratrol and quercetin, are suggested to play an important role as MMPs inhibitors, thereby opening new insights into their applications in many fields, such as pharmaceutical, cosmetic and food industries. This review summarises the current knowledge on plant-derived natural products with MMP-modulating activities. Most of the reviewed plant-derived products exhibit an inhibitory activity on MMPs. Amongst MMPs, MMP-2 and MMP-9 are the most studied. The expression of MMPs is inhibited through respective signalling pathways, such as MAPK, NF-κB and PI3 kinase pathways, which contribute to the reduction in cancer cell behaviours, such as proliferation and migration. Most studies have employed in vitro models, but a limited number of animal studies and clinical trials have been conducted. Even though plant-derived products show promising results in modulating MMPs, more in vivo studies and clinical trials are needed to support their therapeutic applications in the future.

Bone Marrow Niches for Skeletal Progenitor Cells and their Inhabitants in Health and Disease

2019 ◽  
Vol 14 (4) ◽  
pp. 305-319 ◽  
Author(s):  
Marietta Herrmann ◽  
Franz Jakob
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Adult Stem Cells ◽  
Current Knowledge ◽  
Cell Populations ◽  
Surface Markers ◽  
Bone Marrow Niches

The bone marrow hosts skeletal progenitor cells which have most widely been referred to as Mesenchymal Stem or Stromal Cells (MSCs), a heterogeneous population of adult stem cells possessing the potential for self-renewal and multilineage differentiation. A consensus agreement on minimal criteria has been suggested to define MSCs in vitro, including adhesion to plastic, expression of typical surface markers and the ability to differentiate towards the adipogenic, osteogenic and chondrogenic lineages but they are critically discussed since the differentiation capability of cells could not always be confirmed by stringent assays in vivo. However, these in vitro characteristics have led to the notion that progenitor cell populations, similar to MSCs in bone marrow, reside in various tissues. MSCs are in the focus of numerous (pre)clinical studies on tissue regeneration and repair.Recent advances in terms of genetic animal models enabled a couple of studies targeting skeletal progenitor cells in vivo. Accordingly, different skeletal progenitor cell populations could be identified by the expression of surface markers including nestin and leptin receptor. While there are still issues with the identity of, and the overlap between different cell populations, these studies suggested that specific microenvironments, referred to as niches, host and maintain skeletal progenitor cells in the bone marrow. Dynamic mutual interactions through biological and physical cues between niche constituting cells and niche inhabitants control dormancy, symmetric and asymmetric cell division and lineage commitment. Niche constituting cells, inhabitant cells and their extracellular matrix are subject to influences of aging and disease e.g. via cellular modulators. Protective niches can be hijacked and abused by metastasizing tumor cells, and may even be adapted via mutual education. Here, we summarize the current knowledge on bone marrow skeletal progenitor cell niches in physiology and pathophysiology. We discuss the plasticity and dynamics of bone marrow niches as well as future perspectives of targeting niches for therapeutic strategies.

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