AHR
Description
The AHR (aryl hydrocarbon receptor) is a protein-coding gene located on chromosome 7.
The aryl hydrocarbon receptor (also known as AhR, AHR, ahr, ahR, AH receptor, or as the dioxin receptor) is a protein that in humans is encoded by the AHR gene. The aryl hydrocarbon receptor is a transcription factor that regulates gene expression. It was originally thought to function primarily as a sensor of xenobiotic chemicals and also as the regulator of enzymes such as cytochrome P450s that metabolize these chemicals. The most notable of these xenobiotic chemicals are aromatic (aryl) hydrocarbons from which the receptor derives its name. More recently, it has been discovered that AhR is activated (or deactivated) by a number of endogenous indole derivatives such as kynurenine. In addition to regulating metabolism enzymes, the AhR has roles in regulating immune cells, stem cell maintenance, and cellular differentiation. The aryl hydrocarbon receptor is a member of the family of basic helix-loop-helix transcription factors. AhR binds several exogenous ligands such as natural plant flavonoids, polyphenols and indoles, as well as synthetic polycyclic aromatic hydrocarbons and dioxin-like compounds. AhR is a cytosolic transcription factor that is normally inactive, bound to several co-chaperones. Upon ligand binding to chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the chaperones dissociate resulting in AhR translocating into the nucleus and dimerizing with ARNT (AhR nuclear translocator), leading to changes in gene transcription.
Ligand-activated transcription factor that enables cells to adapt to changing conditions by sensing compounds from the environment, diet, microbiome and cellular metabolism, and which plays important roles in development, immunity and cancer (PubMed:30373764, PubMed:23275542, PubMed:7961644, PubMed:32818467). Upon ligand binding, translocates into the nucleus, where it heterodimerizes with ARNT and induces transcription by binding to xenobiotic response elements (XRE) (PubMed:30373764, PubMed:23275542, PubMed:7961644). Regulates a variety of biological processes, including angiogenesis, hematopoiesis, drug and lipid metabolism, cell motility and immune modulation (PubMed:12213388). Xenobiotics can act as ligands: upon xenobiotic- binding, activates the expression of multiple phase I and II xenobiotic chemical metabolizing enzyme genes (such as the CYP1A1 gene) (PubMed:7961644). Mediates biochemical and toxic effects of halogenated aromatic hydrocarbons (PubMed:7961644, PubMed:34521881). Next to xenobiotics, natural ligands derived from plants, microbiota, and endogenous metabolism are potent AHR agonists (PubMed:18076143). Tryptophan (Trp) derivatives constitute an important class of endogenous AHR ligands (PubMed:32866000, PubMed:32818467). Acts as a negative regulator of anti-tumor immunity: indoles and kynurenic acid generated by Trp catabolism act as ligand and activate AHR, thereby promoting AHR-driven cancer cell motility and suppressing adaptive immunity (PubMed:32818467). Regulates the circadian clock by inhibiting the basal and circadian expression of the core circadian component PER1 (PubMed:28602820). Inhibits PER1 by repressing the CLOCK-BMAL1 heterodimer mediated transcriptional activation of PER1 (PubMed:28602820). The heterodimer ARNT:AHR binds to core DNA sequence 5'-TGCGTG-3' within the dioxin response element (DRE) of target gene promoters and activates their transcription (PubMed:28602820). {ECO:0000269|PubMed:23275542, ECO:0000269|PubMed:28602820, ECO:0000269|PubMed:30373764, ECO:0000269|PubMed:32818467, ECO:0000269|PubMed:32866000, ECO:0000269|PubMed:34521881, ECO:0000269|PubMed:7961644, ECO:0000303|PubMed:12213388, ECO:0000303|PubMed:18076143}
AHR is also known as RP85, bHLHe76.
