Department of Biology, University of Nevada, Reno, Reno, NV, USA.
Department of Biology, University of Nevada, Reno, Reno, NV, USA.
Cell Rep. 2019 Jun 25;27(13):3808-3817.e7. doi: 10.1016/j.celrep.2019.05.083.
Many metazoan genes express alternative long 3' UTR isoforms in the nervous system, but their functions remain largely unclear. In Drosophila melanogaster, the Dscam1 gene generates short and long (Dscam1-L) 3' UTR isoforms because of alternative polyadenylation (APA). Here, we found that the RNA-binding protein Embryonic Lethal Abnormal Visual System (Elav) impacts Dscam1 biogenesis at two levels, including regulation of long 3' UTR biogenesis and skipping of an upstream exon (exon 19). MinION long-read sequencing confirmed the connectivity of this alternative splicing event to the long 3' UTR. Knockdown or CRISPR deletion of Dscam1-L impaired axon outgrowth in Drosophila. The Dscam1 long 3' UTR was found to be required for correct Elav-mediated skipping of exon 19. Elav thus co-regulates APA and alternative splicing to generate specific Dscam1 transcripts that are essential for neural development. This coupling of APA to alternative splicing might represent a new class of regulated RNA processing.
许多后生动物基因在神经系统中表达选择性的长 3' UTR 异构体，但它们的功能仍很大程度上不清楚。在黑腹果蝇中，Dscam1 基因由于选择性多聚腺苷酸化（APA）而产生短和长（Dscam1-L）3' UTR 异构体。在这里，我们发现 RNA 结合蛋白 Embryonic Lethal Abnormal Visual System (Elav) 在两个水平上影响 Dscam1 的生物发生，包括长 3' UTR 生物发生的调节和上游外显子（外显子 19）的跳过。MinION 长读测序证实了这种选择性剪接事件与长 3' UTR 的连接。Dscam1-L 的敲低或 CRISPR 缺失损害了果蝇的轴突生长。发现 Dscam1 长 3' UTR 对于正确的 Elav 介导的外显子 19 跳过是必需的。因此，Elav 共同调节 APA 和选择性剪接，以产生对神经发育至关重要的特定 Dscam1 转录本。这种 APA 与选择性剪接的偶联可能代表一类新的受调控的 RNA 加工。
