title: The aryl hydrocarbon receptor in barrier organ physiology, immunology, and toxicology.
abstract: The aryl hydrocarbon receptor (AhR) is an evolutionarily old transcription factor belonging to the Per-ARNT-Sim-basic helix-loop-helix protein family. AhR translocates into the nucleus upon binding of various small molecules into the pocket of its single-ligand binding domain. AhR binding to both xenobiotic and endogenous ligands results in highly cell-specific transcriptome changes and in changes in cellular functions. We discuss here the role of AhR for immune cells of the barrier organs: skin, gut, and lung. Both adaptive and innate immune cells require AhR signaling at critical checkpoints. We also discuss the current two prevailing views-namely, 1) AhR as a promiscuous sensor for small chemicals and 2) a role for AhR as a balancing factor for cell differentiation and function, which is controlled by levels of endogenous high-affinity ligands. AhR signaling is considered a promising drug and preventive target, particularly for cancer, inflammatory, and autoimmune diseases. Therefore, understanding its biology is of great importance.
authors: Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany (C.E.); and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (A.R.) chesser@uni-duesseldorf.de.
authors: Charlotte
authors: C
authors: Esser
authors: Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany (C.E.); and Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (A.R.).
authors: Agneta
authors: A
authors: Rannug
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000276:immunology / Q000382:microbiology / Q000502:physiology*; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects; D008024:Ligands; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D008954:Models, Biological; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D012867:Skin / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D012879:Skin Physiological Phenomena / Q000187:drug effects; D015262:Xenobiotics / Q000633:toxicity
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D008024:Ligands; D018336:Receptors, Aryl Hydrocarbon; D015262:Xenobiotics; C111235:AHR protein, human