Pregnane X receptor

From Wikipedia, the free encyclopedia


Nuclear receptor subfamily 1, group I, member 2
PDB rendering based on 1ilg.
Available structures: 1ilg, 1ilh, 1m13, 1nrl, 1skx, 2o9i
Identifiers
Symbol(s) NR1I2; SAR; PAR1; PAR2; PRR; BXR; ONR1; PAR; PARq; PXR; SXR
External IDs OMIM: 603065 MGI: 1337040 HomoloGene: 40757
RNA expression pattern

More reference expression data
Orthologs
Human Mouse
Entrez 8856 18171
Ensembl ENSG00000144852 ENSMUSG00000022809
Uniprot O75469 Q0P525
Refseq NM_003889 (mRNA)
NP_003880 (protein)		 NM_010936 (mRNA)
NP_035066 (protein)
Location Chr 3: 120.98 - 121.02 Mb Chr 16: 38.17 - 38.21 Mb
Pubmed search [1] [2]

In the field of molecular biology, the pregnane X receptor (PXR), also known as NR1I2 (nuclear receptor subfamily 1, group I, member 2), is a nuclear receptor whose primary function is to sense the presence of foreign toxic substances and in response up regulate the expression of proteins involved in the detoxification and clearance of these substance from the body.[1]

PXR is encoded by the NR1I2 gene. The product of this gene belongs to the nuclear receptor superfamily, members of which are transcription factors characterized by a ligand-binding domain and a DNA-binding domain. The encoded protein is a transcriptional regulator of the cytochrome P450 gene CYP3A4, binding to the response element of the CYP3A4 promoter as a heterodimer with the 9-cis retinoic acid receptor RXR. It is activated by a range of compounds that induce CYP3A4, including dexamethasone and rifampicin. Several alternatively spliced transcripts encoding different isoforms, some of which use non-AUG (CUG) translation initiation codon, have been described for this gene. Additional transcript variants exist, however, they have not been fully characterized.[2]

Contents

[edit] Activation

PXR is activated by a large number of endogenous and exogenous chemicals including steroids, antibiotics, antimycotics, bile acids, and hyperforin, a constituent of the herbal antidepressant St. John's Wort.

[edit] Function

Like other type II nuclear receptors, when activated, it forms a heterodimer with the retinoid X receptor, and binds to hormone response elements on DNA which elicits expression of gene products.

One of the primary targets of PXR activation is the induction of CYP3A4, an important phase I oxidative enzyme that is responsible for the metabolism of many drugs.

In addition, PXR up regulates the expression of phase II conjugating enzymes such as glutathione S-transferase and phase III transport uptake and efflux proteins such as OATP2 (SLCO2A1 ) and MDR1 (ABCB1).

[edit] References

  1. ^ Kliewer S, Goodwin B, Willson T (2002). "The nuclear pregnane X receptor: a key regulator of xenobiotic metabolism". Endocr. Rev. 23 (5): 687–702. doi:10.1210/er.2001-0038. PMID 12372848. 
  2. ^ Entrez Gene: NR1I2 nuclear receptor subfamily 1, group I, member 2.

[edit] Further reading

  • Watkins RE, Noble SM, Redinbo MR (2002). "Structural insights into the promiscuity and function of the human pregnane X receptor.". Current opinion in drug discovery & development 5 (1): 150–8. PMID 11865669. 
  • Maruyama K, Sugano S (1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides.". Gene 138 (1-2): 171–4. PMID 8125298. 
  • Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, et al. (1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library.". Gene 200 (1-2): 149–56. PMID 9373149. 
  • Kliewer SA, Moore JT, Wade L, et al. (1998). "An orphan nuclear receptor activated by pregnanes defines a novel steroid signaling pathway.". Cell 92 (1): 73–82. PMID 9489701. 
  • Lehmann JM, McKee DD, Watson MA, et al. (1998). "The human orphan nuclear receptor PXR is activated by compounds that regulate CYP3A4 gene expression and cause drug interactions.". J. Clin. Invest. 102 (5): 1016–23. PMID 9727070. 
  • Bertilsson G, Heidrich J, Svensson K, et al. (1998). "Identification of a human nuclear receptor defines a new signaling pathway for CYP3A induction.". Proc. Natl. Acad. Sci. U.S.A. 95 (21): 12208–13. PMID 9770465. 
  • Blumberg B, Sabbagh W, Juguilon H, et al. (1998). "SXR, a novel steroid and xenobiotic-sensing nuclear receptor.". Genes Dev. 12 (20): 3195–205. PMID 9784494. 
  • Dotzlaw H, Leygue E, Watson P, Murphy LC (1999). "The human orphan receptor PXR messenger RNA is expressed in both normal and neoplastic breast tissue.". Clin. Cancer Res. 5 (8): 2103–7. PMID 10473093. 
  • Geick A, Eichelbaum M, Burk O (2001). "Nuclear receptor response elements mediate induction of intestinal MDR1 by rifampin.". J. Biol. Chem. 276 (18): 14581–7. doi:10.1074/jbc.M010173200. PMID 11297522. 
  • Watkins RE, Wisely GB, Moore LB, et al. (2001). "The human nuclear xenobiotic receptor PXR: structural determinants of directed promiscuity.". Science 292 (5525): 2329–33. doi:10.1126/science.1060762. PMID 11408620. 
  • Zhang J, Kuehl P, Green ED, et al. (2001). "The human pregnane X receptor: genomic structure and identification and functional characterization of natural allelic variants.". Pharmacogenetics 11 (7): 555–72. PMID 11668216. 
  • Gonzalez MM, Carlberg C (2002). "Cross-repression, a functional consequence of the physical interaction of non-liganded nuclear receptors and POU domain transcription factors.". J. Biol. Chem. 277 (21): 18501–9. doi:10.1074/jbc.M200205200. PMID 11891224. 
  • Takeshita A, Taguchi M, Koibuchi N, Ozawa Y (2002). "Putative role of the orphan nuclear receptor SXR (steroid and xenobiotic receptor) in the mechanism of CYP3A4 inhibition by xenobiotics.". J. Biol. Chem. 277 (36): 32453–8. doi:10.1074/jbc.M111245200. PMID 12072427. 
  • Frungieri MB, Weidinger S, Meineke V, et al. (2003). "Proliferative action of mast-cell tryptase is mediated by PAR2, COX2, prostaglandins, and PPARgamma : Possible relevance to human fibrotic disorders.". Proc. Natl. Acad. Sci. U.S.A. 99 (23): 15072–7. doi:10.1073/pnas.232422999. PMID 12397176. 
  • Fukuen S, Fukuda T, Matsuda H, et al. (2002). "Identification of the novel splicing variants for the hPXR in human livers.". Biochem. Biophys. Res. Commun. 298 (3): 433–8. PMID 12413960. 
  • Strausberg RL, Feingold EA, Grouse LH, et al. (2003). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. doi:10.1073/pnas.242603899. PMID 12477932. 
  • Chang TK, Bandiera SM, Chen J (2003). "Constitutive androstane receptor and pregnane X receptor gene expression in human liver: interindividual variability and correlation with CYP2B6 mRNA levels.". Drug Metab. Dispos. 31 (1): 7–10. PMID 12485946. 
  • Dussault I, Yoo HD, Lin M, et al. (2003). "Identification of an endogenous ligand that activates pregnane X receptor-mediated sterol clearance.". Proc. Natl. Acad. Sci. U.S.A. 100 (3): 833–8. doi:10.1073/pnas.0336235100. PMID 12569201. 
  • Kawana K, Ikuta T, Kobayashi Y, et al. (2003). "Molecular mechanism of nuclear translocation of an orphan nuclear receptor, SXR.". Mol. Pharmacol. 63 (3): 524–31. PMID 12606758. 

[edit] External links

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

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v • d • e
Transcription factors and intracellular receptors
(1) Basic domains
(1.1) Basic leucine zipper (bZIP)
Activating transcription factor (AATF, 1, 2, 3, 4, 5, 6, 7) • AP-1 (c-Fos, FOSB, FOSL1, FOSL2, c-Jun, JUNB, JUND) • BACH (1, 2) • BATF • BLZF1 • C/EBP (α, β, γ, δ, ε, ζ) • CREB (1, 3, L1) • CREM • DBP • DDIT3 • GABPA • HLF • MAF (B, F, G, K) • NFE (2, L1, L2) • NRL • NRF1 • XBP1
(1.2) Basic helix-loop-helix (bHLH)
ATOH1 • AhR • AHRR • ARNT • ASCL1 • BHLHB2 • BMAL (ARNTL, ARNTL2) • CLOCK • EPAS1 • HAND (1, 2) • HES (5, 6) • HEY (1, 2, L) • HES1 • HIF (1A, 3A) • ID (1, 2, 3, 4) • LYL1 • MXD4 • MYCL1 • MYCN • Myogenic regulatory factors (MyoD, Myogenin, MYF5, MYF6) • Neurogenins • NeuroD (1, 2) • NPAS (1, 2, 3) • OLIG (1, 2) • Scleraxis • TAL1 • Twist • USF1
(1.3) bHLH-ZIP
MAX • MITF • MNT • MLX • MXI1 • Myc • SREBP (1, 2)
(1.6) Basic helix-span-helix (bHSH)
(2) Zinc finger
DNA-binding domains
(2.1) Nuclear receptor (Cys4)
subfamily 1 (Thyroid hormone (α, β), CAR, FXR, LXR (α, β), PPAR (α, β/δ, γ), PXR, RAR (α, β, γ), ROR (α, β, γ), Rev-ErbA (α, β), VDR) • subfamily 2 (COUP-TF (I, II), Ear-2, HNF4 (α, γ), PNR, RXR (α, β, γ), Testicular receptor (2, 4), TLX) • subfamily 3 (Steroid hormone (Estrogen (α, β), Estrogen related (α, β, γ), Androgen, Glucocorticoid, Mineralocorticoid, Progesterone)) • subfamily 4 NUR (NGFIB, NOR1, NURR1) • subfamily 5 (LRH-1, SF1) • subfamily 6 (GCNF) • subfamily 0 (DAX1, SHP)
(2.2) Other Cys4
GATA (1, 2, 3, 4, 5, 6) • MTA (1, 2, 3)
(2.3) Cys2His2
ATBF1 • BCL(6, 11A, 11B) • CTCF • E4F1 • EGR (2, 3) • ERV3 • General transcription factors (TFIIA, TFIIB, TFIID, TFIIE, TFIIF: 1, 2, TFIIH: 1, 2, 4, 2I, 3A, 3C1, 3C2) • GFI1 • GLI-Krüppel family (1, 2, 3, YY1) • HIC (1, 2) • HIVEP (1, 2, 3) • IKZF (1, 2, 3) • ILF (2, 3) • KLF (2, 4, 5, 6, 9, 10, 11, 12, 13) • MTF1 • MYT1 • OSR1 • Sp1 • zinc finger ((3, 7, 9, 10, 19, 22, 24, 33B, 34, 35, 41, 43, 44, 51, 74, 143, 146, 148, 165, 202, 217, 219, 238, 239, 259, 267, 268, 281, 295, 318, 330, 346, 350, 365, 366, 384, 451, 452, 471, 593, 638, 649, 655) • Zbtb7 (7A) • ZBT (16, 17, 33)
(2.4) Cys6
(2.5) Alternating composition
AIRE • DIDO1 • GRLF1 • ING (1, 2, 4) • JARID (1A, 1B, 1C, 1D, 2) • JMJD1B
(3) Helix-turn-helix
domains
ARX • CDX (1, 2) • CRX • CUTL1 • DLX (3, 4, 5) • EMX2 • EN (1, 2) • FHL (1, 2, 3) • HESX1 • HHEX • HLX • Homeobox (A1, A3, A4, A5, A7, A9, A10, A11, A13, B1, B2, B3, B4, B5, B6, B7, B8, B9, B13, C4, C5, C6, C8, C9, C10, C11, C13, D1, D3, D4, D8, D9, D10, D11, D12, D13) • HOPX • MEIS (1, 2) • MEOX2 • MNX1 • MSX (1, 2) • NANOG • NKX (2-1, 2-5, 3-1) • PHF (3, 6, 10, 17) • POU domain (PIT-1, BRN-3: 1, 2, Octamer transcription factor: 1, 2, 3/4, 6, 7) • OTX (1, 2) • PDX1
(3.2) Paired box
PAX (1, 2, 3, 4, 5, 6, 7, 8, 9)
E2F (1, 2, 3, 4, 5) • FOX proteins (C1, C2, E1, G1, H1, K2, L2, M1, N3, O1A, , O3A, O4, P1, P2, P3)
HSF (1, 2, 4)
(3.5) Tryptophan clusters
ELF (4, 5) • EGF • ELK (1, 3, 4) • ERF • ERG • ETS (1, 2) • ETV (1, 4, 5, 6) • FLI1 • Interferon regulatory factors (1, 2, 3, 4, 5, 6, 7, 8) • MYB • MYBL2
(3.6) TEA domain
transcriptional enhancer factor 1, 2
(4) β-Scaffold factors with
minor groove contacts
(4.1) Rel homology region
NF-κB (NFKB1, NFKB2, REL, RELA, RELB) • NFAT (C1, C2, C3, C4, 5)
(4.2) STAT
STAT (1, 2, 3, 4, 5, 6)
(4.3) p53
(4.4) MADS box
Mef2 (A, B, C, D) • SRF
HNF (1A, 1B) • LEF1 • SOX (2, 3, 4, 5, 6, 8, 9, 10, 11, 13, 15, 18) • SRY • SSRP1
(4.10) Cold-shock domain
(4.11) Runt
(0) Other
transcription factors
(0.2) HMGI(Y)
HMGA (1, 2) • HBP1
Rb • RBL1 • RBL2
(0.5) AP-2/EREBP-related factors
Apetala 2 • EREBP • B3
(0.6) Miscellaneous
ARID (1A, 1B, 2, 3A, 3B, 4A) • CAP • IFI (16, 35) • MLL (2, 3, T1) • MNDA • NFI (A, B, C, X) • NFY (A, B, C) • Rho/Sigma • R-SMAD
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