Transcript isoform switching occurs in the murine synaptic transcriptome during aging

Preliminary Summary: In this study, we set to specifically analyze effects of aging on differential splicing in the local synaptic proteome. To this end, we analyzed the RNA extracted from synaptosomes obtained from cerebral cortices of C57BL/6 mice of 3 weeks, 5 months and 19 months of age. Synaptosomes are artificial, membranous sacs that contain synaptic components and are generated by subcellular fractionation of homogenized or ground-up nerve tissue. We employ RNA-seq using paired long-reads to obtain comprehensive sequence information on synaptic transcripts and two different bioinformatic methods (DIEGO and LeafCutter) to quantify differential splicing. Finally, the change in the usage of the selected junctions was validated through RT-qPCR and RT-PCR using an independent set of samples. rRNA-depleted RNA of cortex-derived synaptosomes of 3-weeks, 5-months and 19-months old mice (C57BL/6, 4 biological replicates for each age) were sequenced using Illumina HiSeq 2500 System (paired-end). Total Homogenate samples from 5-months old mice were used for reference.