Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China.
State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, China.
Nat Commun. 2022 Aug 11;13(1):4709. doi: 10.1038/s41467-022-32138-x.
The Ten-eleven translocation (TET) family of dioxygenases mediate cytosine demethylation by catalyzing the oxidation of 5-methylcytosine (5mC). TET-mediated DNA demethylation controls the proper differentiation of embryonic stem cells and TET members display functional redundancy during early gastrulation. However, it is unclear if TET proteins have functional significance in mammalian skeletal development. Here, we report that Tet genes deficiency in mesoderm mesenchymal stem cells results in severe defects of bone development. The existence of any single Tet gene allele can support early bone formation, suggesting a functional redundancy of TET proteins. Integrative analyses of RNA-seq, Whole Genome Bisulfite Sequencing (WGBS), 5hmC-Seal and Assay for Transposase-Accessible Chromatin (ATAC-seq) demonstrate that TET-mediated demethylation increases the chromatin accessibility of target genes by RUNX2 and facilities RUNX2-regulated transcription. In addition, TET proteins interact with RUNX2 through their catalytic domain to regulate cytosine methylation around RUNX2 binding region. The catalytic domain is indispensable for TET enzymes to regulate RUNX2 transcription activity on its target genes and to regulate bone development. These results demonstrate that TET enzymes function to regulate RUNX2 activity and maintain skeletal homeostasis.
十-十一易位（TET）家族的双加氧酶通过催化 5-甲基胞嘧啶（5mC）的氧化来介导胞嘧啶去甲基化。TET 介导的 DNA 去甲基化控制胚胎干细胞的适当分化，并且在早期原肠胚形成过程中 TET 成员显示功能冗余。然而，TET 蛋白在哺乳动物骨骼发育中是否具有功能意义尚不清楚。在这里，我们报告说，中胚层间充质干细胞中 Tet 基因的缺失导致骨发育的严重缺陷。任何单个 Tet 基因等位基因的存在都可以支持早期骨形成，这表明 TET 蛋白具有功能冗余性。RNA-seq、全基因组亚硫酸氢盐测序（WGBS）、5hmC-封阻和转座酶可及染色质（ATAC-seq）的综合分析表明，TET 介导的去甲基化通过 RUNX2 增加靶基因的染色质可及性，并促进 RUNX2 调节的转录。此外，TET 蛋白通过其催化结构域与 RUNX2 相互作用，以调节 RUNX2 结合区域周围的胞嘧啶甲基化。催化结构域对于 TET 酶调节 RUNX2 对其靶基因的转录活性和调节骨骼发育是不可或缺的。这些结果表明，TET 酶的功能是调节 RUNX2 活性并维持骨骼内稳态。
