Tet2调节骨髓间充质干细胞功能

Tet2 regulates the function of mesenchymal stem cells

摘要:

Tet2 (Tet家族成员2) 在DNA去甲基化修饰、表观遗传调控及骨髓造血中起着重要作用。笔者课题组前期研究发现，随着年龄增长，Tet2敲除小鼠逐步发展为淋系白血病和髓系白血病。但Tet2在骨髓微环境中的作用仍不清楚。进一步研究发现，Tet2敲除的骨髓间充质干细胞 (Mesenchymal stem cells，MSC)更多处于G2/M分裂期，其细胞分裂时间缩短，生长速度加快。长周期培养-起始细胞实验表明，Tet2敲除的MSC支持造血干细胞扩增和髓系分化的能力增强。通过点杂交实验发现，Tet2敲除后，骨髓细胞DNA总甲基化水平升高。对Tet2缺失的骨髓细胞进行甲基化测序，结果表明：基因组转录调控区域等多个功能性结构域的甲基化水平明显升高。同时，敲除Tet2的MSC分泌IL-8、IL-18等炎性细胞因子的能力下降；敲除Tet2的MSC更多分泌促进造血干细胞髓系分化的GM-CSF和CCL-3等细胞因子。Tet2可以影响间充质干细胞造血支持作用，进而调节造血。

Abstract:

Tet2 (member 2 of the Tet family) plays an important role in DNA demethylation modification, epigenetic regulation, and hematopoiesis. In our previous study, we found that Tet2 knockout mice progressively developed lymphocytic leukemia and myeloid leukemia with aging. However，the role of Tet2 in bone marrow microenvironment is unclear. Here in this study, we found that more Tet2-/- mesenchymal stem cells (MSCs) from bone marrow were in the G2/M cell cycle stages. The division time of Tet2-/- MSCs was shorter than that of the control cells. The growth rate of Tet2-/- MSCs was accelerated. The cobblestone area-forming cells assay (CAFC) showed that Tet2 knockout MSCs supported the expansion of hematopoietic stem cells (HSCs) and the differentiation of HSCs was skewed towards myeloid cells. Through the dot blotting experiment, we found that the total methylation level was increased in Tet2-/- bone marrow cells (BM). We used the methylation-chip to analyze the methylation level of Tet2-/- bone marrow cells and found that the level of methylation was increased in the transcriptional starting area (TSS), exons (EXONS) and 3? untranslated region (3? UTR). Moreover, we found that the cytokines secreted by Tet2-/- MSCs, such as IL-8 and IL-18, were decreased. While the expressions of GM-CSF and CCL-3, which supported hematopoietic stem cells to differentiate to myeloid cells, were increased in Tet2-/- MSCs. Our results demonstrated that Tet2 regulates MSCs to support hematopoiesis.