Research Article A Possible Role of HMGB1 in DNA Demethylation in CD4+ T

Copyright © 2013 Yaping Li et al.This is an open access article distributed under the Creative CommonsAttribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The aberrant activity of CD4+ T cells in patients with systemic lupus erythematosus (SLE) is associated with DNA hypomethylation of the regulatory regions in CD11a and CD70 genes. Our previous studies demonstrated that Gadd45a contributes to the development of SLE by promoting DNA demethylation in CD4+ T cells. In this study, we identified proteins that bind to Gadd45a in CD4+ T cells during SLE flare by using the method of co-immunoprecipitation andmass spectrometry, Highmobility group box protein 1 (HMGB1) is one of identified proteins. Furthermore, gene and protein expression of HMGB1 was significantly increased in SLE CD4+ T cells compared to controls, andHMGB1mRNAwas correlated with CD11a and CD70mRNA. A significant, positive correlation was found betweenHMGB1mRNA and SLEDAI for SLE patients. Our data demonstrate that HMGB1 binds to Gadd45a and may be involved in DNA demethylation in CD4+ T cells during lupus flare. 1