Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA.
Department of Developmental Biology, Sloan Kettering Institute, New York, NY 10065, USA; Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
Mol Cell. 2020 Oct 1;80(1):140-155.e6. doi: 10.1016/j.molcel.2020.09.007.
The tissue-specific deployment of highly extended neural 3' UTR isoforms, generated by alternative polyadenylation (APA), is a broad and conserved feature of metazoan genomes. However, the factors and mechanisms that control neural APA isoforms are not well understood. Here, we show that three ELAV/Hu RNA binding proteins (Elav, Rbp9, and Fne) have similar capacities to induce a lengthened 3' UTR landscape in an ectopic setting. These factors promote accumulation of chromatin-associated, 3' UTR-extended, nascent transcripts, through inhibition of proximal polyadenylation site (PAS) usage. Notably, Elav represses an unannotated splice isoform of fne, switching the normally cytoplasmic Fne toward the nucleus in elav mutants. We use genomic profiling to reveal strong and broad loss of neural APA in elav/fne double mutant CNS, the first genetic background to largely abrogate this distinct APA signature. Overall, we demonstrate how regulatory interplay and functionally overlapping activities of neural ELAV/Hu RBPs drives the neural APA landscape.
高度延伸的神经 3' UTR 异构体的组织特异性表达,是由可变多聚腺苷酸化(APA)产生的,这是后生动物基因组的一个广泛而保守的特征。然而,控制神经 APA 异构体的因素和机制还不是很清楚。在这里,我们表明,三种 ELAV/Hu RNA 结合蛋白(Elav、Rbp9 和 Fne)在异位环境中具有相似的诱导延长 3' UTR 景观的能力。这些因子通过抑制近端多聚腺苷酸化位点(PAS)的使用,促进染色质相关、3' UTR 延伸的新生转录本的积累。值得注意的是,Elav 抑制了 fne 的一个未注释的剪接异构体,使正常位于细胞质中的 Fne 在 elav 突变体中转向细胞核。我们利用基因组分析揭示了 elav/fne 双突变体中枢神经系统中强烈而广泛的神经 APA 缺失,这是第一个在很大程度上消除这种独特的 APA 特征的遗传背景。总的来说,我们展示了神经 ELAV/Hu RBPs 的调控相互作用和功能重叠活动如何驱动神经 APA 景观。