DNA methylation in the regulation of T cell LFA-1 expression.
Inducing T cell LFA-1 overexpression by transfection, or by treatment with DNA methylation inhibitors including 5-azacytidine, procainamide and hydralazine, causes MHC-specific T cell autoreactivity in vitro and autoimmunity in vivo. How DNA methylation inhibitors increase LFA-1 expression is unknown. In this report we identify a mechanism by which DNA methylation affects LFA-1 expression. Nuclear run-on assays demonstrated that inhibiting DNA methylation increased transcription of CD11a but not CD18 or beta-actin mRNA. CD11a mRNA stability was not affected. Transfection of hypomethylated cells with reporter constructs containing the CD11a promoter showed no role for overexpression of transcription factors. However, the CD11a promoter demethylated following treatment with DNA methyltransferase inhibitors, and in vitro methylation of the construct suppressed its expression. Together, these results indicate that DNA methylation inhibitors can cause LFA-1 overexpression directly by demethylating the CD11a promoter. This mechanism could contribute to T cell autoreactivity, and potentially to autoimmunity.
Kaplan
M J
MJ
Department of Internal Medicine,  University of Michigan, Ann Arbor 48109, USA.
Deng
C
C
Yang
J
J
Richardson
B C
BC
D001374:Azacitidine / Q000494:pharmacology; D002461:Cell Line, Transformed; D019175:DNA Methylation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D019169:Jurkat Cells; D016169:Lymphocyte Function-Associated Antigen-1 / Q000235:genetics*; D011342:Procainamide / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D014158:Transcription, Genetic / Q000187:drug effects
D004791:Enzyme Inhibitors; D016169:Lymphocyte Function-Associated Antigen-1; D011342:Procainamide; D001374:Azacitidine