Nuclear receptors in lipid metabolism and toxicity (Danio rerio)

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Right click for commentsDIETDIETXenobioticsGene expressionLOC791965vdrbCholesterolzgc:63920abcc21,25-Dihydroxy-Vitamins D3cyp3a65zgc:162197OxysterolCYP2B6cyp26a1ABCB1CYP4B1ABCC3cyp3a65CYP1A2nr1h3CYP2C9zgc:63920CYP2C9cyp3a65ppargIsoprenoidspparabABCB4Bile Acidsabca1atpteRARAabca1aabcg67-DehydroCholesterolppardbCYP27B1Acetyl CoAcyp24a1lCYP8B1Retinoic acidFatty AcidsrargbSteroidsNR1I3rargaCYP2E1abca1aLanosterolCYP2C9abcg5nr1h4ABCD2abcd3azgc:63920nr1i2CYP2B6ABCB11


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 55% conversion rate.

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History

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CompareRevisionActionTimeUserComment
107094view14:17, 17 September 2019MaintBotChEBI identifier normalization
106067view11:58, 16 August 2019MaintBotHMDB identifier normalization
96394view09:54, 12 March 2018EgonwReplaced a secondary ChEBI identifier with a primary identifier.
78352view09:34, 7 January 2015MaintBotadded missing graphIds
68630view04:42, 6 July 2013MaintBotUpdated to 2013 gpml schema
67537view11:22, 26 June 2013DdiglesOntology Term : 'lipid metabolic pathway' added !
47921view22:15, 18 April 2012KhanspersUpdating from human to fix xref duplication
40796view22:16, 1 March 2011MaintBotRemoved redundant pathway information and comments
35687view22:56, 12 February 2010KhanspersDescription
35685view22:55, 12 February 2010KhanspersModified description
34185view21:23, 9 December 2009MaintBotAutomatic update of empty xrefs
31917view12:51, 14 August 2009MaintBotFixed group labels
31036view01:16, 30 July 2009MaintBotNew pathway

External references

DataNodes

View all...
NameTypeDatabase referenceComment
1,25-Dihydroxy-Vitamins D3Metabolite
7-DehydroCholesterolMetabolite
ABCB1GeneProduct
ABCB11GeneProduct
ABCB4GeneProduct
ABCC3GeneProduct
ABCD2GeneProduct
Acetyl CoAMetabolite
Bile AcidsMetabolite3098 (ChEBI)
CYP1A2GeneProduct
CYP27B1GeneProduct
CYP2B6GeneProduct
CYP2C9GeneProduct
CYP2E1GeneProduct
CYP4B1GeneProduct
CYP8B1GeneProduct
CholesterolMetabolite
Fatty AcidsMetabolite35366 (ChEBI)
IsoprenoidsMetabolite24913 (ChEBI)
LOC791965GeneProduct791965 (Entrez Gene)
LanosterolMetabolite6374 (ChEBI)
NR1I3GeneProduct
OxysterolMetabolite
RARAGeneProduct
Retinoic acidMetaboliteHMDB01852 (HMDB)
SteroidsMetabolite
abca1aGeneProduct558924 (Entrez Gene)
abcc2GeneProduct393561 (Entrez Gene)
abcd3aGeneProduct406803 (Entrez Gene)
abcg5GeneProduct557317 (Entrez Gene)
abcg6GeneProduct
cyp24a1lGeneProduct100004700 (Entrez Gene)
cyp26a1GeneProduct30381 (Entrez Gene)
cyp3a65GeneProduct553969 (Entrez Gene)
nr1h3GeneProduct548341 (Entrez Gene)
nr1h4GeneProduct436847 (Entrez Gene) Farnesoid X-activated receptor
nr1i2GeneProduct565875 (Entrez Gene)
pparabGeneProduct557714 (Entrez Gene)
ppardbGeneProduct30754 (Entrez Gene)
ppargGeneProduct557037 (Entrez Gene)
rargaGeneProduct30606 (Entrez Gene)
rargbGeneProduct100034753 (Entrez Gene)
tpteGeneProduct327292 (Entrez Gene)
vdrbGeneProduct564511 (Entrez Gene)
zgc:162197GeneProduct556979 (Entrez Gene)
zgc:63920GeneProduct394148 (Entrez Gene)

Annotated Interactions

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