Polyaromatic hydrocarbon receptors (PAH receptors), also known as aryl hydrocarbon receptors (AHR), are a group of intracellular receptor proteins found in many organisms, including humans. They are primarily known for their role in mediating the toxic effects of polyaromatic hydrocarbons (PAHs), a class of pollutants that are generated from the incomplete burning of organic matter.
PAH receptors are present in various cell types, such as liver, lung, and skin cells, and are typically localized in the cytoplasm. They function as ligand-activated transcription factors, meaning they can bind to specific chemicals and regulate the expression of target genes involved in detoxification and defense mechanisms.
When PAH compounds enter an organism, they can bind to PAH receptors and form a complex that translocates to the nucleus. In the nucleus, this complex binds to specific DNA sequences known as xenobiotic response elements (XREs) within the promoters of target genes. This binding initiates or suppresses the transcription of these genes, leading to the production of proteins involved in xenobiotic metabolism and cellular detoxification.
PAH receptors play a crucial role in protecting organisms from the harmful effects of environmental pollutants, as they are responsible for the induction of enzymes and other proteins that help metabolize and eliminate these toxic compounds. However, chronic activation of PAH receptors can also lead to adverse effects, including immune system modulation, disruption of endocrine function, and promotion of carcinogenesis.
Overall, PAH receptors are essential molecular sensors that play a critical role in the cellular response to environmental pollutants, particularly polyaromatic hydrocarbons.
