DNA METHYLATION AND T CELL CYTOKINE GENE EXPRESSION

最近几个实验室的研究结果表明，T细胞中细胞因子基因的差异表达是通过细胞因子基因染色质结构和甲基化的差异而在表观遗传学上强制执行的。然而，DNA甲基化在体内这一过程中的作用尚未得到直接测试。我们有可用的小鼠，其中主要的DNA甲基转移酶基因（Dnmtl）在CD 4 + CD 8+（DP）阶段的T细胞发育期间被选择性和有效地消除（CD 4 Cre Dnmt 21 ox小鼠）。这些小鼠的T细胞发育基本正常。我们建议使用这些小鼠来确定DNA甲基化在细胞因子基因表达调控中的作用。具体而言，我们将解决以下假设：首先，缺乏Dnmt 1的初始CD 4和CD 8 T细胞在初级活化后比来自对照小鼠的初始T细胞更容易产生效应细胞因子（需要更少的细胞分裂）。其次，Dnmt-/- T细胞表达的细胞因子模式的差异将不如对照T细胞明显。第三，Dnmt的缺失将导致细胞因子基因位点周围的染色质结构更加开放。第四，来自CD 4 Cre Dnmt 21 ox小鼠的CD 4和CD 8 T细胞将不能发展和维持细胞因子基因表达的可遗传的、极化的1型对2型模式。最后，CD 4 Cre Dnmt 21 ox小鼠将有利于细胞因子基因的双等位基因表达而不是单等位基因表达。

Recent findings from several laboratories suggest that differential cytokine gene expression in T cells is epigenetically enforced through differences in cytokine gene chromatin structure and methylation. However, the role of DNA methylation in this process in vivo has not been tested directly. We have available mice in which the major DNA methyltransferase gene (Dnmtl) is selectively and efficiently ablated during T cell development at the CD4+CD8+ (DP) stage (CD4 Cre Dnmt 21ox mice). T cell development in these mice is essentially normal. We propose to use these mice to determine the role of DNA methylation in the regulation of cytokine gene expression. Specifically, we will address the following hypotheses: First, naive CD4 and CD8 T cells lacking Dnmt 1 will produce effector cytokines more readily (requiring fewer cell divisions) after primary activation than naive T cells from control mice. Second, differences in the pattern of cytokines expressed by Dnmt-/- T cells will be less evident than in control T cells. Third, the loss of Dnmt will result in a more open chromatin structure surrounding cytokine gene loci. Fourth, CD4 and CD8 T cells from CD4 Cre Dnmt 21ox mice will be unable to develop and maintain a heritable, polarized type 1 vs. type 2 pattern of cytokine gene expression. Lastly, CD4 Cre Dnmt 21ox mice will favor biallelic over monoallelic expression of cytokine genes.