Abstract: ObjectiveTo explore the molecular mechanism of DNA methylation alteration induced by hydroquinone (HQ). MethodsHQ was prepared by PBS buffer and bone marrow mesenchymal stem cells (BMMSCs) were treated with PBS served as the control. The genes and protein expression of PARP-1 and DNA methyltransferase ( DNMTs) , DNMT1, DNMT3a and DNMT3b in BMMSCs exposed to 2.5, 5.0, 10.0, and 20.0 μmol?L-1 HQ were tested by real-time fluorescence quantitive PCR and Western blotting.ResultsThe genes and protein expression of PARP-1 and DNMT1 were increased in a dose-dependent manner. The regression equations of genes were y ?=0.030 x+1.283 and y ?=0.075 x+1.088. The regression equations of protein were y ?=0.025 x+1.234 and y ?=0.043 x+1.097. But the gene and protein expressions of DNMT3a were decreased in a dose-dependent manner. The regression equations of gene and protein were y ?=-0.040 x+1.151 and y ?=-0.012 x+1.021, respectively.ConclusionThe change of global DNA methylation induced by HQ may be associated with the deregulated expressions of DNMTs, and PARP-1 may participate in global DNA hypomethylation induced by HQ.