The methyltransferase activity of Setd2 is essential for mouse embryonic development: establishment of a mouse model harboring a patient-derived Setd2 mutation

The histone methyltransferase SETD2 is responsible for the transcription-coupled trimethylation of histone H3 lysine 36 (H3K36me3) on all protein-coding genes through its direct interaction with the elongating form of RNA polymerase II. In mice, Setd2 is required for embryonic development, as the Setd2-null mice are embryonic lethal due to impaired vascular remodeling. In human, SETD2 is frequently mutated in various types of cancer, thus representing one of the major chromatin-modification defects that drive tumorigenesis. Notably, recent studies suggest that, despite the central roles of their catalytic activities, many chromatin modifiers contain important non-catalytic (so-called "moonlighting") functions, which are largely substantiated by their roles in protein-protein interactions. This notion is somewhat consistent with the observation that the cancer-associated SETD2 mutations are seemingly localized throughout the whole protein, thus raising a question whether the major function(s) of SETD2 is solely dependent on its methyltransferase activity. As an answer to this question, in this short report, we have established a site-specific Setd2 knock-in mouse model harboring a patient-derived, catalytic dead Setd2 and have provided clear evidence supporting that the requirement of Setd2 in mouse embryonic development is definitely dependent on its methyltransferase activity. However, it is also notable that, in comparison with the Setd2-null mice, the Setd2 catalytic dead mice showed slightly mild defects in embryonic development and gene expression changes, suggesting potential non-catalytic functions of Setd2, which could be studied in the future by using these different Setd2 mouse models. Mouse embryos and yolk sacs mRNA profiles of Setd2-null (wild type-WT, heterozygous-HE, homozygous-HO) and Setd2 catalytic dead (wild type-WT, heterozygous-HE, homozygous-HO) at embryonic day 9.5 (E9.5).Two replicates in each group.组蛋白甲基转移酶SETD2（histone methyltransferase SETD2）可通过与RNA聚合酶II（RNA polymerase II）的延伸形式直接相互作用，介导所有蛋白编码基因上组蛋白H3赖氨酸36的转录偶联三甲基化修饰（H3K36me3）。在小鼠中，Setd2是胚胎发育所必需的，Setd2敲除小鼠会因血管重塑受损而出现胚胎致死表型。在人类中，SETD2在多种癌症类型中频繁发生突变，因此是驱动肿瘤发生的主要染色质修饰缺陷因子之一。值得注意的是，近期研究表明，尽管染色质修饰因子的催化活性发挥核心功能，但众多此类因子还具备重要的非催化功能，即所谓的“兼职（moonlighting）”功能，这一结论在其参与蛋白质-蛋白质相互作用的过程中得到了大量验证。这一观点与癌症相关SETD2突变似乎遍布整个蛋白序列的观测结果基本一致，由此引出一个核心问题：SETD2的主要功能是否完全依赖于其甲基转移酶活性。为解答该问题，本研究在这份简短报告中构建了携带患者来源催化失活型Setd2的位点特异性敲入小鼠模型，并提供了明确证据，证实小鼠胚胎发育对Setd2的需求完全依赖于其甲基转移酶活性。但同样值得关注的是，与Setd2敲除小鼠相比，Setd2催化失活小鼠在胚胎发育及基因表达变化层面仅表现出轻微缺陷，这提示Setd2可能存在潜在的非催化功能，未来可借助这两类不同的Setd2小鼠模型对其展开深入研究。本数据集包含胚胎发育第9.5天（embryonic day 9.5, E9.5）的Setd2敲除（野生型（wild type, WT）、杂合型（heterozygous, HE）、纯合型（homozygous, HO））及Setd2催化失活（野生型、杂合型、纯合型）小鼠胚胎与卵黄囊的mRNA转录组谱，每组设置两个生物学重复。