TET2 Regulates Mast Cell Differentiation and Proliferation through Catalytic and Non-catalytic Activities.

Dioxygenases of the TET family impact genome functions by converting 5-methylcytosine in DNA to 5-hydroxymethylcytosine, but the individual contribution of the three family members to differentiation and function of myeloid cells is still incompletely understood. Using cells with a deletion in the Tet2 gene, we show that TET2 contributes to the regulation of mast cell differentiation, proliferation and effector functions. The differentiation defect observed in absence of TET2 could be however completely rescued or further exacerbated by modulating TET3 activity, and it was primarily linked to dysregulated expression of the C/EBP family of transcription factors. In contrast, hyper-proliferation induced by the lack of TET2 could not be modified by TET3. Together, our data indicate the existence of both overlapping and unique roles of individual TET proteins in regulating myeloid cell gene expression, proliferation and function. Total mRNA of FACS-sorted Kit+ FcεRIα+ populations of primary bone marrow-derived mast cells (BMMCs) from Tet2-/- and Tet2+/+ animals was extracted and subjected to multiparallel sequencing.

TET家族双加氧酶（TET family dioxygenases）可通过将DNA中的5-甲基胞嘧啶（5-methylcytosine）转化为5-羟甲基胞嘧啶（5-hydroxymethylcytosine）影响基因组功能，但该家族三个成员各自对髓系细胞（myeloid cells）分化与功能的贡献仍未完全阐明。本研究利用Tet2基因敲除细胞开展实验，结果显示TET2参与调控肥大细胞（mast cell）的分化、增殖及效应功能。然而，TET2缺失时观察到的分化缺陷，既可通过调控TET3活性完全挽救，也可进一步加剧；该缺陷主要与C/EBP家族转录因子（C/EBP family of transcription factors）的表达失调密切相关。与之相反，TET2缺失诱导的细胞过度增殖，并不能通过调控TET3活性得到改变。综上，本研究数据表明，单个TET蛋白在调控髓系细胞基因表达、增殖及功能的过程中，既存在功能重叠，也具备独特作用。本研究提取了来自Tet2敲除（Tet2-/-）与野生型（Tet2+/+）动物的原代骨髓源性肥大细胞（primary bone marrow-derived mast cells, BMMCs）中经FACS分选的Kit+ FcεRIα+ 细胞群体的总mRNA，并对其进行了多平行测序（multiparallel sequencing）。