RNA m6A修饰调控脂代谢的机制研究

The homeostasis of lipid metabolism is important for organisms to cope with the changing internal and external environment. The imbalance of lipid metabolism leads to obesity and many major human diseases. Therefore, it is urgent to find conserved new mechanisms that can control lipid metabolism in a systematic manner. N6-methyladenosine (m6A) is the most abundant internal modification of eukaryotic mRNA, which affects every step of the mRNA life cycle and plays important roles in cell differentiation, development and cancer. However, the function of m6A The homeostasis of lipid metabolism is important for organisms to cope with the changing internal and external environment. The imbalance of lipid metabolism leads to obesity and many major human diseases. Therefore, it is urgent to find conserved new mechanisms that can control lipid metabolism in a systematic manner. N6-methyladenosine (m6A) is the most abundant internal modification of eukaryotic mRNA, which affects every step of the mRNA life cycle and plays important roles in cell differentiation, development and cancer. However, the function of m6A modification in lipid metabolism is unclear. We first identified and characterized two core components of the m6A methyltransferase complex in Drosophila. Preliminary experiments indicate that the m6A modification affects the expression of metabolic genes, and the m6A factor mutants exhibit a lipid mobilization phenotype between the fat body and the oenocytes (similar to the mammalian adipose-liver axis). In this proposal, we will further use a variety of metabolic assays and metabolomics to comprehensively resolve the roles of all members of the m6A pathway in lipid metabolism. Combined with deep sequencing technology and genetic interaction experiments, we will pinpoint key genes and sites that are modified by m6A in lipid metabolism regulation. We will also use human cell lines and fungal system to verify that the regulation of m6A modification on lipid metabolism is evolutionarily conserved.

脂代谢的稳态平衡是生物体应对内外环境变化的重要保障，脂代谢失衡会导致肥胖和多种人类重大疾病，因此急需找到在进化中保守的，能在系统水平上对脂代谢进行调控的新机制。N6-甲基腺嘌呤(m6A)是真核生物mRNA上含量最丰富的内部修饰，它影响了mRNA生命周期的每个步骤，并且在细胞分化、个体发育和癌症中发挥重要作用，然而，m6A修饰在脂代谢中的功能却不清楚。申请人前期首次发现和鉴定了果蝇m6A甲基转移酶复合物两个核心因子，预实验表明m6A修饰影响代谢基因的表达，m6A因子突变体出现脂肪体与绛色细胞(类似于哺乳动物的脂肪-肝脏)之间的脂质动员表型。本项目将进一步采用多种检测手段和代谢组学，全面解析m6A通路所有成员在脂代谢中的重要作用。结合深度测序和遗传互作实验，找出在脂代谢调控中受到m6A修饰的关键基因和位点。还将使用人类细胞系和真菌体系验证m6A修饰对脂代谢的调控机制是在进化中保守的。

RNA上的化学修饰代表了新一层表观遗传学的调控机制，并成为最近国内外的研究热点之一。目前已有超过150种RNA修饰被发现，其中N6-甲基腺嘌呤 (N6-methyladenosine, m6A) 是mRNA上含量最丰富的化学修饰。m6A修饰作为一条新的通路，它如何在系统水平上对糖脂代谢进行调控仍不清楚。本项目使用果蝇作为模式动物，采用脂质代谢、m6A测序、分子生物学、遗传学、细胞生物学、和气相色谱-质谱相结合的手段，确定了RNA m6A这一层新的表观遗传修饰在脂代谢调控过程中的功能。通过m6A-Seq首次构建了高质量的果蝇成体m6A修饰图谱，发现受m6A修饰调控最显著的就是代谢和免疫通路，从中找出一批受到m6A修饰的关键基因和修饰位点，并正在验证和完善其具体分子机理。部分研究成果于2021年在Nature Communications杂志（第二标注资助基金）发表，并被该杂志选为特别重要的Editors’ Highlights论文。总之，本项目的研究计划得到了较好的执行，项目的研究目标得到了较好的完成，在RNA表观修饰和糖脂代谢这两个方向做出了一定贡献。