GSE169023
RNA Sequencing analyses of control and HuD KO (Elavl4 null) mouse cortical transcriptomes
Purpose: The goal of this study was to analyse RNA-seq data to determine the effect of deletion of the RNA-binding protein HuD in transcriptiome-wide alternative splicing and polyadenylation in the neocortex of adult HuD KO vs. wild type littermates (controls) Methods: Cortical mRNA profiles of adult HuD KO (Elavl4 -/-) mice and Control mice were generated by RNA sequencing, in triplicate, using Illumina NovaSeq 6000 platform. The quality of raw RNA-sequencing reads was evaluated using FastQC software (version 0.11.5) and adapters were removed using the Cutadapt (version 1.15) and Trimmomatic (version 0.38) software. Alternative splicing was evaluated using rMATS software (version 4.0.2)  and BAM files were converted to BedGraph before examining alternative polyadenylation using DaPars software (version 0.9.1) Methods (cont.): RNA-seq data was aligned to the M musculus genome (UCSC browser, mm10) using STAR (version 2.7.3a), and MultiQC (version 1.8) was used to perform a final quality check on STAR alignment files. If alignments were found to be the same read length and have >80% reads mapped to a unique location, the data was considered good quality and alternative splicing and polyadenylation analyses were performed. Sequence reads per sample were aligned to the mouse genome (build mm10). Results: HuD KO affected alternative splicing of 310 genes, including 17 validated HuD targets such as Cbx3, Cspp1, Snap25 and Gria2.  In addition, deletion of HuD affected polyadenylation of 53 genes, with the majority of significantly altered mRNAs shifting towards usage of the proximal polyadenylation signal (PAS), resulting in shorter 3' untranslated regions (3' UTRs). Conclusions: HuD KO had a greater effect on alternative splicing than polyadenylation, with many of the affected genes implicated in several neuronal functions and neuropsychiatric disorders. Overall design: We used three biological replicates per genotype: 3 Elavll4-/- ( HuD KO) and 3 wild type (controls)