m6A controls neurogenesis and sex determination in Drosophila via its nuclear reader protein YT521-B [RNA-Seq, S2R+ cells]. Drosophila melanogaster

N6-methyladenosine RNA (m6A) is the most abundant internal mRNA modification in mammals. While its role in the regulation of posttranscriptional gene expression is beginning to be unveiled, its function during development of complex organisms is poorly understood. Here, we identify Spenito as a novel member of the methyltransferase complex and show that m6A in Drosophila is necessary for proper synaptic growth, and in regulation of early steps of pre-mRNA splicing. Splicing of Sex-lethal and of its downstream targets are defective in animals lacking m6A, revealing also important roles in sex determination and dosage compensation. Finally, we implicate the nuclear m6A reader protein, YT521-B, as a crucial effector of m6A modifications in vivo. Altogether, our work provides important novel insights into m6A biology through identification and characterization of both m6A-writing and -reading proteins in Drosophila and their effects on splicing, neurogenesis and sex-determination within the context of the whole animal. Overall design: RNA-Seq in S2R+ cells (7 conditions, triplicates)

N6-甲基腺嘌呤核糖核酸（m6A）是哺乳动物体内丰度最高的mRNA内部修饰。尽管其在转录后基因表达调控中的作用正逐步被揭示，但它在复杂生物体发育过程中的功能仍鲜为人知。本研究中，我们鉴定出Spenito为甲基转移酶复合物的全新成员，并证实果蝇（Drosophila）体内的m6A对于正常突触生长以及前体mRNA（pre-mRNA）剪接的早期调控是必需的。在缺失m6A的果蝇个体中，性别致死（Sex-lethal）及其下游靶基因的剪接存在缺陷，这也揭示了m6A在性别决定与剂量补偿过程中的重要功能。最后，我们证实核内m6A识别蛋白YT521-B是体内m6A修饰发挥功能的关键效应因子。综上，本研究通过鉴定并表征果蝇体内的m6A写入与读取蛋白，阐明了二者在整体动物水平对剪接、神经发生及性别决定的调控作用，为m6A生物学研究提供了重要的全新见解。整体实验设计：对S2R+细胞开展RNA测序（RNA-Seq）实验，共设置7种处理条件，每组设置3次重复。