Nuclear receptors in lipid metabolism and toxicity (Bos taurus)

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DIETXenobioticsRight click for commentsGene expressionDIETRARACYP27B1Bile AcidsABCB11LanosterolCYP4B1ABCB1Acetyl CoACYP2E1CYP3A4ABCB4CYP8B1SteroidsLOC615374CYP1A2CYP2C9ABCG5CYP2BRARBRARGLOC510507CholesterolLOC510507ABCA1Fatty AcidsABCD2ABCA1NR1I2PPARDABCC3CYP3A4CYP4A11LOC540080LOC510507CYP2C9CYP2Babcg6IsoprenoidsOxysterolNR1I31,25-Dihydroxy-Vitamins D3NR1H3VDRCYP3A4ABCD3Retinoic acid7-DehydroCholesterolCYP26A1ABCC2ABCG1PPARAPPARGNR1H4CYP2C9ABCA1


Description

Nuclear receptors are transcription factors that are activated upon binding to its ligands. Initially, they had been classified as classic endocrine nuclear hormone receptors and orphan receptors. However, further studies have led to the identification of lipid ligands for some of these ‘adopted’ orphan receptors, which are responsible for lipid metabolism, storage or elimination. One of the characteristics of these receptors is that they act by forming heterodimers with retinoid X receptor (RXR). The receptors include peroxisome proliferators-Activated receptors (PPARs) for fatty acids, liver X receptor (LCR) for oxysterols, Farnesoid X receptors (FXR) for bile acids and steroid xenobiotic receptor/X receptor (SXR/PXR or Nsil2) for xenobiotics. Other orphan receptors also require RXR for its functions are vitamin D receptor (VDR) for vitamin D and retinoic acid receptor (RAR) for retinoid acids, although these receptors are not involved in lipid metabolism. Upon binding to various ligands, three classes of proteins are synthesized including lipid binding proteins, the ATP-binding cassette (ABC) transporters and cytochrome P450 member proteins which catalyzes lipid anabolism, metabolism and elimination. In addition to lipid metabolism, some members of the cytochrome P450 family genes are responsible for activation of procarcinogens, detoxification of environmental toxins and metabolism of drugs and xenobiotics. In particular, CAR, Nsil2 and recently identified VDR are important in up-regulation of these cytochromes. Of all the human cytochrome P450 genes, only a few CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4 account for most toxicity effects, specifically CYP3A is responsible for clearing approximately half of the clinically prescribed drugs. For instance, acetaminophen, one of the most commonly used drug, is toxic in high doses due to the activation of CAR and the drug’s subsequentconversion to acetyl-p-benzoquinone imine (NAPQI) by CYP1A2, CYP2E1 and CYP3A.

Comments

GenMAPP notes 
Nuclear receptors are transcription factors that are activated upon binding to its ligands. Initially, they had been classified as classic endocrine nuclear hormone receptors and orphan receptors. However, further studies have led to the identification of lipid ligands for some of these ‘adopted’ orphan receptors, which are responsible for lipid metabolism, storage or elimination. One of the characteristics of these receptors is that they act by forming heterodimers with retinoid X receptor (RXR). The receptors include peroxisome proliferators-Activated receptors (PPARs) for fatty acids, liver X receptor (LCR) for oxysterols, Farnesoid X receptors (FXR) for bile acids and steroid xenobiotic receptor/X receptor (SXR/PXR or Nsil2) for xenobiotics. Other orphan receptors also require RXR for its functions are vitamin D receptor (VDR) for vitamin D and retinoic acid receptor (RAR) for retinoid acids, although these receptors are not involved in lipid metabolism. Upon binding to various ligands, three classes of proteins are synthesized including lipid binding proteins, the ATP-binding cassette (ABC) transporters and cytochrome P450 member proteins which catalyzes lipid anabolism, metabolism and elimination.


In addition to lipid metabolism, some members of the cytochrome P450 family genes are responsible for activation of procarcinogens, detoxification of environmental toxins and metabolism of drugs and xenobiotics. In particular, CAR, Nsil2 and recently identified VDR are important in up-regulation of these cytochromes. Of all the human cytochrome P450 genes, only a few CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4 account for most toxicity effects, specifically CYP3A is responsible for clearing approximately half of the clinically prescribed drugs. For instance, acetaminophen, one of the most commonly used drug, is toxic in high doses due to the activation of CAR and the drug’s subsequentconversion to acetyl-p-benzoquinone imine (NAPQI) by CYP1A2, CYP2E1 and CYP3A.

GenMAPP remarks 
Converted to human by GenMAPP.org
HomologyConvert 
This pathway was inferred from Homo sapiens pathway WP299(r21309) with a 68% conversion rate.

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History

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CompareRevisionActionTimeUserComment
117571view11:22, 21 May 2021EweitzModified title
107077view14:16, 17 September 2019MaintBotChEBI identifier normalization
105942view11:47, 16 August 2019MaintBotHMDB identifier normalization
96300view18:03, 7 March 2018EgonwReplaced a secondary ChEBI identifier with a primary identifier.
80762view15:25, 30 June 2015Mkutmonhomology conversion
78597view14:51, 7 January 2015MaintBotadded missing graphIds
70173view00:42, 13 July 2013AlexanderPicoModified title
67542view11:23, 26 June 2013DdiglesOntology Term : 'lipid metabolic pathway' added !
63398view00:04, 10 May 2013MaintBotUpdated to 2013 gpml schema
48130view05:49, 9 May 2012MaintBotUpdating from human to fix xref duplication
40571view19:32, 1 March 2011MaintBotRemoved redundant pathway information and comments
35680view22:50, 12 February 2010KhanspersDescription
35678view22:49, 12 February 2010KhanspersModified description
33809view00:20, 9 December 2009MaintBotAutomatic update of empty xrefs
33625view10:03, 1 December 2009MaintBotRemoved group label
30550view21:59, 29 July 2009MaintBotNew pathway

External references

DataNodes

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NameTypeDatabase referenceComment
1,25-Dihydroxy-Vitamins D3Metabolite
7-DehydroCholesterolMetabolite
ABCA1GeneProduct535379 (Entrez Gene)
ABCB11GeneProduct531150 (Entrez Gene)
ABCB1GeneProduct281585 (Entrez Gene)
ABCB4GeneProduct783154 (Entrez Gene)
ABCC2GeneProduct520925 (Entrez Gene)
ABCC3GeneProduct533151 (Entrez Gene)
ABCD2GeneProduct526436 (Entrez Gene)
ABCD3GeneProduct526059 (Entrez Gene)
ABCG1GeneProduct510745 (Entrez Gene)
ABCG5GeneProduct515536 (Entrez Gene)
Acetyl CoAMetabolite
Bile AcidsMetabolite3098 (ChEBI)
CYP1A2GeneProduct503552 (Entrez Gene)
CYP26A1GeneProduct539047 (Entrez Gene)
CYP27B1GeneProduct539630 (Entrez Gene)
CYP2BGeneProduct504769 (Entrez Gene)
CYP2C9GeneProduct
CYP2E1GeneProduct282213 (Entrez Gene)
CYP3A4GeneProduct507988 (Entrez Gene)
CYP4A11GeneProduct511890 (Entrez Gene)
CYP4B1GeneProduct540149 (Entrez Gene)
CYP8B1GeneProduct538964 (Entrez Gene)
CholesterolMetabolite
Fatty AcidsMetabolite35366 (ChEBI)
IsoprenoidsMetabolite24913 (ChEBI)
LOC510507GeneProduct510507 (Entrez Gene)
LOC540080GeneProduct540080 (Entrez Gene)
LOC615374GeneProduct615374 (Entrez Gene)
LanosterolMetabolite6374 (ChEBI)
NR1H3GeneProduct507176 (Entrez Gene)
NR1H4GeneProduct540528 (Entrez Gene) Farnesoid X-activated receptor
NR1I2GeneProduct493713 (Entrez Gene)
NR1I3GeneProduct493711 (Entrez Gene)
OxysterolMetabolite
PPARAGeneProduct281992 (Entrez Gene)
PPARDGeneProduct353106 (Entrez Gene)
PPARGGeneProduct281993 (Entrez Gene)
RARAGeneProduct534280 (Entrez Gene)
RARBGeneProduct
RARGGeneProduct540425 (Entrez Gene)
Retinoic acidMetaboliteHMDB01852 (HMDB)
SteroidsMetabolite
VDRGeneProduct533656 (Entrez Gene)
abcg6GeneProduct

Annotated Interactions

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