[Show abstract][Hide abstract] ABSTRACT: The role of DNA methyl transferase I (DNMT1) in allergic inflammation was investigated. Antigen stimulation decreased expression of DNMT1 in rat basophilic leukemia cells (RBL2H3). The down regulation of DNMT1 induced expression of histone deacetylase 3 (HDAC3). HDAC3 was necessary for allergic skin inflammation, such as such as triphasic cutaneous reaction and passive cutaneous anaphylaxis. The down regulation of DNMT1 resulted from activation of PKC and rac1 which were necessary for proteasome-dependent ubiquitination of DNMT1 by antigen stimulation. N-acetyl-L-cysteine, an inhibitor of reactive oxygen species production, exerted negative effects on allergic skin inflammation. Antigen stimulation led to increased expression of Tip60, a histone acetyl transferase. Wild type, but not mutant form, Tip60 decreased expression of DNMT1 while increasing expression of HDAC3, suggesting role for acetylation in ubiquitin-dependent proteasomal degradation of DNMT1. In vivo down regulation of DNMT1 increased ear thickness, typical of allergic skin inflammation, induced vascular leakage and promoted angiogenesis in BALB/c mouse. The down regulation of DNMT1 enhanced angiogenic potential of rat aortic endothelial cells (RAEC) accompanied by activation of VEGR-2 and induced interaction between VEGR-2 and syk in RAEC. The enhanced angiogenic potential of RAEC was associated with the induction of VEGF by down regulation of DNMT1 in RBL2H3 cells. The down regulation of DNMT1 induced leukocytes-endothelial cell interaction and expression of various adhesion molecules. Aspirin exerted a negative effect on allergic skin inflammation by indirect regulation on DNMT1 via Tip60. Taken together, these results suggest novel role for DNMT1 in allergic skin inflammation.
[Show abstract][Hide abstract] ABSTRACT: We have shown the induction of histone deacetylase 3 (HDAC3) in antigen-stimulated rat basophilic leukemia cells via NF-κB. We investigated the role of HDAC3 in allergic skin inflammation. We used a BALB/c mouse model of triphasic cutaneous anaphylaxis (triphasic cutaneous reaction; TpCR) and passive cutaneous anaphylaxis (PCA) to examine the role of HDAC3 in allergic skin inflammation. Triphasic cutaneous reaction involved induction of HDAC3 and was mediated by HDAC3. HDAC3 showed an interaction with FcεRIβ. Trichostatin A (TSA), an inhibitor of HDAC(s), disrupted this interaction. Cytokine array analysis showed that the down-regulation of HDAC3 led to the decreased secretion of monocyte chemoattractant protein 1 (MCP1). FcεRI was necessary for induction of HDAC3 and MCP1. ChIP assays showed that HDAC3, in association with Sp1 and c-Jun, was responsible for induction of MCP1 expression. TSA exerted a negative effect on induction of MCP1. HDAC3 exerted a negative regulation on expression of HDAC2 via interaction with Rac1. The down-regulation of HDAC3 or inactivation of Rac1 induced binding of HDAC2 to MCP1 promoter sequences. TSA exerted a negative effect on HDAC3-mediated TpCR. The BALB/c mouse model of PCA involved induction of HDAC3 and MCP1. HDAC3 and MCP1 were necessary for PCA that involved ear swelling, enhanced vascular permeability, and angiogenesis. Recombinant MCP1 enhanced β-hexosaminidase activity and histamine release and also showed angiogenic potential. TSA exerted a negative effect on PCA. Our data show HDAC3 as a valuable target for the development of allergic skin inflammation therapeutics.