AHR: a nuclear receptor for aryl hydrocarbons involved in xenobiotic metabolism, cell cycle regulation, and development in response to both endogenous and environmental signals. AhR was initially identified as a receptor for dioxins, which are environmental pollutants generated by waste incineration and other industrial processes . AhR ligands include polycyclic aromatic hydrocarbons, including the carcinogen benzo(a)pyrene and other components of cigarette smoke. Naturally occurring AhR ligands include flavonoids, which are aromatic plant secondary compounds commonly found in vegetables and fruits. Cytoplasmic aryl hydrocarbon receptors are found in protein complexes with heat shock proteins. Upon ligand binding, AhR dissociates from heat shock proteins and translocate to the nucleus where it dimerizes with AhR nuclear translocator (ARNT, HIF-1b). The AhR/ARNT heterodimer binds to nuclear xenobiotic response elements to control the expression of genes associated with xenobiotic metabolism, including several cytochrome P450 genes. AhR is ubiquitously expressed and is thought to play a role in regulation of cell proliferation and differentiation, cytokine expression, and xenobiotic metabolism. Research studies link AhR activity with the control of regulatory T-cell and T-helper 17 cell differentiation, regulation of the inflammatory response, and the onset of lung cancer.
Protein type: DNA-binding; Transcription factor; Nuclear receptor
Chromosomal Location of Human Ortholog: 7p15
Cellular Component: nucleoplasm; transcription factor complex; cytoplasm; nucleus
Molecular Function: RNA polymerase II transcription factor activity, enhancer binding; protein dimerization activity; signal transducer activity; protein binding; ligand-dependent nuclear receptor activity; DNA binding; sequence-specific DNA binding; protein heterodimerization activity; Hsp90 protein binding; transcription factor activity; transcription factor binding
Biological Process: transcription from RNA polymerase II promoter; prostate gland development; blood vessel development; intracellular receptor-mediated signaling pathway; apoptosis; response to toxin; positive regulation of transcription, DNA-dependent; negative regulation of transcription from RNA polymerase II promoter; cell cycle; regulation of transcription from RNA polymerase II promoter; response to xenobiotic stimulus; regulation of transcription, DNA-dependent; regulation of gene expression; xenobiotic metabolic process; positive regulation of transcription from RNA polymerase II promoter; regulation of B cell proliferation; circadian regulation of gene expression; positive regulation of transcriptional preinitiation complex assembly; negative regulation of transcription, DNA-dependent
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