Regulation of dimethylarginine dimethylaminohydrolase 2 expression by NF-κB acetylation

Nitric oxide (NO) serves a crucial role in the kidney and is synthesized by NO synthase (NOS). Asymmetrical dimethylarginine is an endogenous inhibitor of NOS that is metabolized by dimethylarginine dimethylaminohydrolase (DDAH). To investigate the role of acetylation in DDAH2 expression, 293 cells were treated with trichostatin A (TSA), a deacetylase inhibitor and the mRNA and protein levels were assessed using quantitative PCR and western blotting respectively. Its promoter activity was detected using a luciferase assay. The effect of TSA on NF-κB acetylation was tested after immunoprecipitation. The binding of NF-κB to the DDAH2 promoter was analyzed using an electrophoretic mobility shift assay and chromatin immunoprecipitation. TSA upregulated DDAH2 expression and transcriptional activity of the DDAH2 promoter through a NF-κB responsive element, which is located at the -1582 to -1573 position of the DDAH2 promoter. Furthermore, TSA treatment promoted NF-κB acetylation, resulting in enhanced NF-κB binding affinity to its binding site both in vitro and in vivo. Taken together, the present study demonstrated that NF-κB acetylation upregulated DDAH2 expression by enhancing the binding ability of NF-κB to the DDAH2 promoter, resulting in increased promoter activity. The results provided a possible mechanism underlying the regulation of NO production in renal cells and a potential target for treating certain NO-associated renal disorders.