The Peptide Near the C Terminus Regulates Receptor CAR Nuclear Translocation Induced by Xenochemicals in Mouse Liver

Zelko, Igor N.; Sueyoshi, Tatsuya; Kawamoto, Takeshi; Moore, Rick; Negishi, Masahiko

doi:10.1128/mcb.21.8.2838-2846.2001

Cited by 145 publications

(128 citation statements)

References 26 publications

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“…PB, TCPOBOP, and ITS liquid media supplement were obtained from Sigma (St. Louis, MO); HGF was obtained from Chemicon (Temecula, CA); U0126 was obtained from Promega (Madison, WI); EGF and U0124 were obtained from Calbiochem (San Diego, CA); anti-rabbit IgG was obtained from Santa Cruz biotechnology (Santa Cruz, CA); anti-ERK1/2 and anti-phospho-ERK1/2 were obtained from Cell Signaling Technology (Danvers, MA); androstenol was obtained from Steraloids (Newport, RI). All plasmids used were previously constructed; pcDNA 3 mCAR, PBREM-tk-luciferase reporter, and Ϫ1.8-kb CYP2B6 promoter in pGL3, phRL-tk Zelko et al, 2001;Kobayashi et al, 2003;Swales et al, 2005).…”

Section: Methodsmentioning

confidence: 99%

Extracellular Signal-Regulated Kinase Is an Endogenous Signal Retaining the Nuclear Constitutive Active/Androstane Receptor (CAR) in the Cytoplasm of Mouse Primary Hepatocytes

Koike¹,

Moore²,

Negishi³

2007

Mol Pharmacol

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The nuclear receptor constitutive active/androstane receptor (CAR) is sequestered in the cytoplasm of liver cells before its activation by therapeutic drugs and xenobiotics such as phenobarbital (PB) and 1,4-Bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) in mouse liver, the regulatory mechanism of which remains poorly understood. Given the finding that epidermal growth factor repressed PB activation of CAR-mediated transcription (Mol Pharmacol 65:172-180, 2004), here we investigated the regulatory role of hepatocyte growth factor (HGF)-mediated signal in sequestering CAR in the cytoplasm of mouse primary hepatocytes. HGF treatment effectively repressed the induction of endogenous CYP2b10 gene by PB and TCPOBOP in mouse primary hepatocytes. On the other hand, inhibition by 1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene (U0126) of an HGF downstream kinase mitogenactivated protein kinase kinase (MEK) induced the Cyp2b10 gene and up-regulated the CAR-regulated promoter activity in the absence of TCPOBOP. HGF treatment increased phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in the cytosol, thus decreasing the TCPOBOP-induced nuclear accumulation of CAR. In contrast, U0126 dephosphorylated ERK1/2 and increased nuclear CAR accumulation in the absence of TCPOBOP. These results are consistent with the conclusion that the HGF-dependent phosphorylation of ERK1/2 is the endogenous signal that sequesters CAR in the cytoplasm of mouse primary hepatocytes.The nuclear constitutive active/androstane receptor CAR is a xeno-sensing transcription factor that regulates numerous hepatic genes in response to a large group of chemicals and therapeutic drugs. Phenobarbital (PB) represents this group of xenobiotics; it not only induces drug metabolism and secretion but also elicits pleiotropic effects on liver functions. These effects include metabolism and secretion of endobiotics (such as bilirubin), and changes in energy metabolism, cell growth, cell-cell communication, and tumor promotion (Honkakoski and Negishi, 1998a). Activation of CAR by drugs such as PB is paramount to elicit these effects by up-or down-regulating the genes that encode the key proteins and enzymes for these liver functions (Kodama and Negishi, 2006). As the function of CAR has expanded, deciphering the molecular mechanism of its activation by drugs is an urgent subject of current investigations.Mouse hepatocytes retain CAR in the cytoplasm, thus making the nuclear translocation an initial step of its acti-

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Section: Methodsmentioning

confidence: 99%

Extracellular Signal-Regulated Kinase Is an Endogenous Signal Retaining the Nuclear Constitutive Active/Androstane Receptor (CAR) in the Cytoplasm of Mouse Primary Hepatocytes

Koike¹,

Moore²,

Negishi³

2007

Mol Pharmacol

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“…When the epidermal growth factor receptor (EGFR) signal is activated, dephosphorylation of CAR at threonine 38 is repressed. Upon activation, EGFR signaling phosphorylates extracellular signal-regulated kinase ERK1/2, enabling phospho-ERK1/2 to bind a previously characterized peptide motif called the xenochemical response signal of CAR (Zelko et al, 2001), preventing threonine 38 from being dephosphorylated. In addition, EGFR signaling also phosphorylates RACK1 at tyrosine 52, preventing RACK1 from interacting with CAR and activating PP2Ac to dephosphorylate threonine 38 (Mutoh et al, 2013).…”

Section: Phenobarbital Induction Mechanismmentioning

confidence: 99%

Phenobarbital Meets Phosphorylation of Nuclear Receptors

Negishi

2017

Drug Metab Dispos

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Phenobarbital was the first therapeutic drug to be characterized for its induction of hepatic drug metabolism. Essentially at the same time, cytochrome P450, an enzyme that metabolizes drugs, was discovered. After nearly 50 years of investigation, the molecular target of phenobarbital induction has now been delineated to phosphorylation at threonine 38 of the constitutive androstane receptor (NR1I3), a member of the nuclear receptor superfamily. Determining this mechanism has provided us with the molecular basis to understand drug induction of drug metabolism and disposition. Threonine 38 is conserved as a phosphorylation motif in the majority of both mouse and human nuclear receptors, providing us with an opportunity to integrate diverse functions of nuclear receptors. Here, I review the works and accomplishments of my laboratory at the National Institutes of Health National Institute of Environmental Health Sciences and the future research directions of where our study of the constitutive androstane receptor might take us.

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“…Details of the CYP2B6 (NR1) 2 luciferase plasmid are included in a previous report (Faucette et al, 2006). pCR3-hCAR expression plasmid and fluorescently labeled hCAR (EYFP-hCAR) expression plasmid were constructed as described previously Zelko et al, 2001). The pRL-TK and pRL-SV40 Renilla luciferase plasmids used to normalize firefly luciferase activities were from Promega.…”

Section: Chemicalsmentioning

confidence: 99%

Relative Activation of Human Pregnane X Receptor versus Constitutive Androstane Receptor Defines Distinct Classes of CYP2B6 and CYP3A4 Inducers

Faucette¹,

Zhang²,

Moore³

et al. 2006

J Pharmacol Exp Ther

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262

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Both the human pregnane X receptor (hPXR) and constitutive androstane receptor (hCAR) are capable of regulating CYP3A4 and CYP2B6 gene expression. However, the majority of currently identified CYP3A4 and CYP2B6 inducers are confirmed activators of hPXR but not hCAR. To compare these receptors with respect to their chemical selectivities, 16 drugs known to induce CYP3A4 and/or CYP2B expression were evaluated for relative activation of hPXR versus hCAR. Because of the high basal but low chemical-induced activation of hCAR in immortalized cells, alternative methods were used to evaluate hCAR activation potential. Thirteen of the 16 compounds were classified as moderate to strong hPXR activators. In contrast, carbamazepine (CMZ), efavirenz (EFV), and nevirapine (NVP) were classified as negligible or weak hPXR activators at concentrations associated with efficacious CYP2B6 reporter or endogenous gene induction in primary human hepatocytes, suggesting potential activation of hCAR. Subsequent experiments demonstrated that these three drugs efficiently induced nuclear accumulation of in vivo-transfected enhanced yellow fluorescent protein-hCAR and significantly increased expression of a CYP2B6 reporter gene when hCAR was expressed in CAR Ϫ/Ϫ mice. In addition, using a recently identified, chemically responsive splice variant of hCAR (hCAR3), the hCAR activation profiles of the 16 compounds were evaluated. By combining results from the hPXR-and hCAR3-based reporter gene assays, these inducers were classified as hPXR, hCAR, or hPXR/hCAR dual activators. Our results demonstrate that CMZ, EFV, and NVP induce CYP2B6 and CYP3A4 preferentially through hCAR and that hCAR3 represents a sensitive tool for in vitro prediction of chemical-mediated human CAR activation.CYP3A4 and CYP2B6 are induced at the mRNA, protein, and activity levels by the same compounds, including rifampin, phenobarbital, clotrimazole, cyclophosphamide, calcium channel antagonists, HMG-CoA reductase inhibitors, and thiazolidinediones (Drocourt et al., 2001;Kocarek et al., 2002;Lindley et al., 2002;Sahi et al., 2003;Faucette et al., 2004). Coinduction of these enzymes is mediated through transcriptional activation of the corresponding genes by the nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR), which are capable of binding to the same response elements in the promoter regions of the CYP3A4 and CYP2B6 genes (Goodwin et al

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The Peptide Near the C Terminus Regulates Receptor CAR Nuclear Translocation Induced by Xenochemicals in Mouse Liver

Cited by 145 publications

References 26 publications

Extracellular Signal-Regulated Kinase Is an Endogenous Signal Retaining the Nuclear Constitutive Active/Androstane Receptor (CAR) in the Cytoplasm of Mouse Primary Hepatocytes

Extracellular Signal-Regulated Kinase Is an Endogenous Signal Retaining the Nuclear Constitutive Active/Androstane Receptor (CAR) in the Cytoplasm of Mouse Primary Hepatocytes

Phenobarbital Meets Phosphorylation of Nuclear Receptors

Relative Activation of Human Pregnane X Receptor versus Constitutive Androstane Receptor Defines Distinct Classes of CYP2B6 and CYP3A4 Inducers

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