基于斑马鱼模型研究m6A甲基转移酶Mettl3调控鱼类生长发育的分子机制

Growth is one of the valuable economic traits in genetic improvement of aquaculture animals, and further study into the function of growth-related genes and regulatory networks will make great contribution to genetic breeding in aquaculture. As a new field of RNA epigenetics, m6A modification has been paid more attention for the regulation of various biological processes. However, the functions of m6A methyltransferase Mettl3 in fish growth and development remain unclear. Our previous study shows that loss of Mettl3 in zebrafish led to slower growth rate，smaller size and lower feeding activity levels, but the underlying mechanism of Mettl3-induced impairment of growth and development is still unclear. In this study, based on Mettl3 knockout and overexpressing transgenic zebrafish lines, we aim to investigate the role of Mettl3 in fish growth and development based on the studies of food intake and energy metabolism. Furthermore, we will use bioinformatic prediction, MeRIP-qPCR, LC-MS/MS and other biological technologies to further explore the regulation mechanism of m6A methylation on growth-related genes. It is possible that our studies will not only demonstrate the regulation mechanism of RNA epigenetics on fish growth, but also provide the guidance to breed more excellent aquaculture species.

生长是水产养殖动物遗传改良最有价值的经济性状，深入研究控制生长性状相关基因的功能和调控关系具有重要的遗传育种意义。作为表观遗传学的新兴研究领域，m6A甲基化修饰参与调控生物学过程的重要性已日渐凸显，但关于m6A甲基转移酶Mettl3对鱼类生长发育的调控尚未见报道。申请人前期研究发现，Mettl3基因突变的斑马鱼生长发育缓慢，体型较小，且摄食量减少，但其如何影响斑马鱼生长发育的分子机制尚不清楚。本研究拟以Mettl3基因敲除和过表达转基因斑马鱼为模型，从摄食和能量代谢方面分析Mettl3对斑马鱼生长发育的影响，并利用生物信息学预测、MeRIP-qPCR和LC-MS/MS等方法深入探索m6A甲基化修饰对生长相关靶基因的调控机制。本研究不仅对阐明RNA表观遗传学对鱼类生长的调控机制具有重要的理论意义，而且对鱼类优良养殖品种的培育具有指导作用。

鱼类生长是水产育种研究关注的重要性状之一，深入研究鱼类生长性状相关基因的功能具有重要的遗传育种意义。Mettl3作为催化m6A甲基化形成的甲基转移酶，目前对鱼类生长发育的调控作用及其分子机制尚未见报道。本项目以斑马鱼为研究对象，通过构建Mettl3基因敲除及过表达转基因家系，发现Mettl3是调控鱼类生长发育的新因子。Mettl3敲除后斑马鱼出现存活率低，生长缓慢，摄食量减少和摄食行为减弱，并在孵化后12天大量死亡。然而，我们在Mettl3过表达转基因家系并未观察到明显的生长发育缺陷和摄食能力下降。此外，Mettl3缺失并不影响斑马鱼骨骼和肠道等组织发育，且其在饱食状态下运动行为正常，说明突变体的生长缓慢不是由于骨骼或消化系统发育异常导致。进一步研究发现，Mettl3可通过参与调控鱼类食欲相关通路而影响摄食行为，进而使得斑马鱼外源营养摄取不足而最终导致生长发育受阻，而过表达转基因斑马鱼可一定程度恢复这些基因的mRNA表达量。此外，代谢组的数据显示，Mettl3还参与调控斑马鱼的营养物质代谢，特别是甘油三酯的代谢。本项目首次发现Mettl3具有促进斑马鱼生长和摄食的功能，并揭示了其作用机制是通过介导鱼类食欲相关通路基因的表达而实现。该研究结果对于理解Mettl3及其催化的m6A甲基化修饰调控生长发育的过程具有重要意义，为以后培育出具有快速生长性状的经济鱼类奠定一定的研究基础。