Fig. 4
From: Natural killer cell therapy for hematologic malignancies: successes, challenges, and the future
IDO. The intracellular enzyme Indoleamine 2,3-dioxygenase (IDO) catalyzes tryptophan to kynurenine, a ligand for the aryl hydrocarbon receptor (AHR). Upon kynurenine binding, AHR crosses the nuclear membrane and associates with the AHR nuclear translocator protein (ARNT). The AHR-ARNT complex binds to DNA promotor regions leading to differential expression of genes associated with immune tolerance of malignancy. In NK cells, AHR-ARNT activates transcription of miR-29b and inhibits NK cell maturation and function