The transcription factors GATA2 and microphthalmia-associated transcription factor regulate Hdc gene expression in mast cells and are required for IgE/mast cell–mediated anaphylaxis

摘要

BackgroundHistamine is a critical mediator of IgE/mast cell–mediated anaphylaxis. Histamine is synthesized by decarboxylating the amino acid histidine, a reaction catalyzed by the histidine decarboxylase(Hdc)gene–encoded enzyme HDC. However, regulation of theHdcgene in mast cells is poorly understood. ObjectiveWe sought to investigate thein?vivoregulation of IgE/mast cell–mediated anaphylaxis by the transcription factors GATA2 and microphthalmia-associated transcription factor (MITF) and the mechanisms by which GATA2 and MITF regulateHdcgene expression in mouse and human mast cells. MethodsMice deficient in the transcription factorsGata2, aryl hydrocarbon receptor (Ahr), aryl hydrocarbon receptor repressor (Ahrr), or basic helix-loop-helix family member E40 (Bhlhe40) were assessed for anaphylactic reactions. Chromatin immunoprecipitation sequencing analysis identified putativeHdcenhancers. Luciferase reporter transcription assay confirmed enhancer activities of putative enhancers in theHdcgene. The short hairpin RNA knockdown approach was used to determine the role of MITF in regulating mouse and humanHDCgene expression. ResultsConnective tissue mast cell–specificGata2-deficient mice did not have IgE/mast cell-mediated anaphylaxis. GATA2 induced the expression ofMitf,Ahr,Ahrr, andBhlhe40in mast cells. MITF, but not AHR, AHRR, or BHLHE40, was required for anaphylaxis. MITF bound to an enhancer located 8.8 kb upstream of the transcription start site of theHdcgene and directed enhancer activity. MITF overexpression largely restoredHdcgene expression in theGata2-deficient mast cells. In the human mast cell line LAD2, MITF was required for theHDCgene expression and histamine synthesis. ConclusionThe transcription factors GATA2 and MITF regulateHdcgene expression in mast cells and are required for IgE/mast cell–mediated anaphylaxis.