m6A甲基化介导linc-MP1的A-to-I编辑对猪肌细胞增殖调控及产肉性状的影响

Myoblast proliferation is the basis of skeletal muscle growth development, and directly affects the formation of pig meat production traits. m6A methylation and A-to-I RNA editing are the two most extensive post-transcriptional modifications in mammalian genome. m6A methylation can negatively regulate A-to-I editing, but their functions and mechanisms in myoblast proliferation are still clear. Based on the RNA-seq and MeRIP-seq data of skeletal muscle development, we found a new long intergenic noncoding RNA, linc-MP1, which was in the upstream of myogenic regulator MyoD and could regulate myoblast proliferation. Bioinformatics analysis showed that linc-MP1 had abundant m6A methylation and A-to-I RNA editing modifications, and the A-to-I editing of one site could influence the binding of linc-MP1 with miR-378. Based on above facts, we suppose that m6A methylation can inhibit the A-to-I editing of linc-MP1, influence its target binding with miR-378, eventually affect the porcine myoblast proliferation and the formation of meat production traits. This project will validate and elucidate the above scientific hypothesis at the molecular, cellular, individual and population levels. It is the first to reveal the regulation mechanism of porcine myoblast proliferation from the perspective of post-transcriptional modifications, this will provide a new perspective and new direction for the study of porcine meat production traits.

肌细胞增殖是骨骼肌生长发育的基础，直接影响猪产肉性状形成。m6A甲基化和A-to-I RNA编辑是动物基因组中最广泛的转录后修饰，m6A甲基化可负调控A-to-I编辑，但是其在肌细胞增殖中的功能和机制仍不清楚。申请者基于骨骼肌发育的RNA-seq和MeRIP-seq数据，在生肌决定因子MyoD上游新发现一个调控肌细胞增殖的长链非编码RNA—linc-MP1，分析表明linc-MP1存在丰富的m6A甲基化和A-to-I编辑修饰，其中一个位点的A-to-I编辑影响linc-MP1与miR-378靶向结合。基于此，推测m6A甲基化通过抑制linc-MP1的A-to-I编辑，调控其与miR-378的结合，影响猪肌细胞增殖和产肉性状形成。本项目将在分子、细胞、个体和群体水平验证并阐释本组提出的上述科学假说。率先从转录后修饰互作角度揭示猪肌细胞增殖的调控机制，为猪产肉性状研究提供新视角和新方向。

肌细胞增殖是骨骼肌生长发育的基础，直接影响猪产肉性状形成。m6A甲基化和A-to-I RNA编辑是动物基因组中最广泛的转录后修饰，m6A甲基化可负调控A-to-I编辑，但是其在肌细胞增殖中的功能和机制仍不清楚。申请者基于骨骼肌发育的RNA-seq和MeRIP-seq数据，在生肌决定因子MyoD上游新发现一个调控肌细胞增殖的长链非编码RNA—linc-MP1。本项目建立了基于转录组和重测序数据高效鉴定猪RNA编辑位点的方法和技术平台。分析了m6A甲基化对肌生成和骨骼肌发育的影响，发现敲低m6A阅读器IGF2BP3促进肌细胞增殖。机制分析表明敲低m6A甲基化转移酶METTL3可以显著降低长链非编码RNA-H19的m6A甲基化水平，并影响肌纤维类型转化。m6A甲基化水平的改变可以影响H19与IGF2BP3的结合能力，从而调控H19的稳定性和骨骼肌发育。linc-MP1在肌肉组织中特异高表达，并且随着骨骼肌的发育，表达水平逐渐降低。功能分析表明，敲低linc-MP1可以抑制骨骼肌细胞增殖、促进肌细胞分化。此外，本项目利用比较转录组鉴定到猪产肉量相关候选基因SATB2和XLOC_036765。本项目揭示了表观修饰调控对骨骼肌发育的重要调控作用，并为猪产肉性状遗传改良提供了候选基因。