Study On Histone Modification Patterns In CD4+T Lymphocytes From Patients With Type 1 Diabetes

Objective:To study histone modification patterns in CD4+T lymphocytes from type 1 diabetic patients, including histone 3 lysine 4 (H3K4) methylation, histone 3 lysine 9 (H3K9) methylation, histone 3 (H3) acetylation and histone 4 (H4) acetylation, and investigate associated histone modification enzymes'gene expression. Intended to provide novel epigenetic insights into the pathogenesis of type 1 diabetes.Methods:We enrolled 32 volunteers into two groups, the first with 16 patients having a diagnosis of type 1 diabetes (9 male,7 female, median 33.1 years, range 15.0-63.0 years)and the second with 16 healthy volunteers (9 male,7 female, median 33.6 years, range 20.0-60.0 years). Peripheral blood mononuclear cells (PBMC) were isolated by the Ficoll method. The CD4+T cells were positively selected by magnetic beads according to the manufacturer's protocol. Histone extraction and detection of global H3K4/H3K9 methylation and histone H3/H4 aetylation were performed following the protocol of Epigentek assay kit. Furthermore, the mRNA levels of selected histone methyltransferases (SET1, SUV39H1 and SUV39H2), histone acetyltransferases (P300 and CREBBP), histone demethylase (LSD1) and histone deacetylases (HDAC1, HDAC2, HDAC5, HDAC7, SIRT1) were determined by using one step real-time quantitative PCR (TaqMan). Results:Reduced global H3K9 methylation(P<0.05) and H3 acetylation(P<0.01) was observed in CD4+T cells of type 1 diabetes patients relative to healthy controls. There was a trend showing reduced H3K4 methylation, but with no statistical significance. However, H4 acetylation lever showed no difference between patients and controls. Type 1 diabetes CD4+T cells H3K4 methylation, H3K9 methylation and H3 acetylation were not related with fasting blood glucose (FBS), postprandial blood glucose (PBS), glycosylated hemoglobin (HbA1c), fasting C-peptide (FCP) and postprandial C-peptide (PCP). A part of selected histone modification enzymes mRNA expression were significantly downregulated in CD4+T cells of type 1 diabetes patients relative to healthy controls, the difference in SET1, SUV39H1, SUV39H2, P300, CREBBP, LSD1, HDAC1, HDAC2, HDAC5, HDAC7 and SIRT1 gene expression in patients compared with healthy controls was-4.8-fold,-7.6-fold,-7.2-fold,-1.9-fold,-4.4-fold,-1.6-fold,-2.5-fold,-2.0-fold,-1.1 fold,-3.4fold,-1.1-fold.Conclusion:Abnormal histone modification patterns including reduced H3K9 methylation and H3 acetylation were observed in CD4+T cells from type 1 diabetes; SET1, SUV39H1, SUV39H2, CREBBP, HDAC1, HDAC2 and HDAC7 gene expression were significantly downregulated in CD4+T cells from type 1 diabetes patients.