TET proteins regulate lineage specification and TCR-mediated expansion of iNKT cells (RNA-Seq)

TET proteins oxidize 5-methylcytosine to 5-hydroxymethylcytosine and further oxidation products in DNA. Here we report that simultaneous deletion of Tet2 and Tet3 in mouse double-positive thymocytes resulted in dysregulated development and proliferation of invariant natural killer T (iNKT) cells. Tet2-Tet3-double-deficient (DKO) iNKT cells displayed pronounced skewing towards the NKT17 lineage, with increased DNA methylation and impaired expression of genes encoding the key lineage-specifying factors T-bet and ThPOK. Transfer of purified Tet2-Tet3 DKO iNKT cells into immunocompetent recipient mice resulted in uncontrolled expansion dependent on the nonclassical MHC protein CD1d, which presents lipid antigens to iNKT cells. Our data indicate that TET proteins regulate iNKT cell fate by ensuring proper development and maturation and suppressing aberrant T cell antigen receptor (TCR)-mediated proliferation. DKO vs. wild typeTET蛋白（TET proteins）可将DNA中的5-甲基胞嘧啶（5-methylcytosine）氧化为5-羟甲基胞嘧啶（5-hydroxymethylcytosine）及其他后续氧化产物。本研究报道，在小鼠双阳性胸腺细胞（mouse double-positive thymocytes）中同时敲除Tet2与Tet3，会导致恒定自然杀伤T（invariant natural killer T, iNKT）细胞的发育与增殖失调。Tet2与Tet3双缺陷（DKO）iNKT细胞呈现出显著的向NKT17细胞谱系偏倚特征，伴随DNA甲基化（DNA methylation）水平升高，以及编码关键谱系特异性转录因子T-bet与ThPOK的基因表达受损。将纯化的Tet2-Tet3 DKO iNKT细胞移植至免疫健全受体小鼠（immunocompetent recipient mice）体内后，会引发失控性增殖，该过程依赖于可向iNKT细胞呈递脂质抗原（lipid antigens）的非经典MHC蛋白CD1d（nonclassical MHC protein CD1d）。本研究数据表明，TET蛋白可通过保障iNKT细胞的正常发育与成熟，并抑制异常的T细胞抗原受体（T cell antigen receptor, TCR）介导的增殖，来调控iNKT细胞的细胞命运。DKO组与野生型组