Diminished transcriptional activity and splicing changes drive gene length-biased rewiring in the aging transcriptome (RNA-Seq)

Here, we use a multi-modal approach to comprehensively characterize age-dependent changes in RNAPII-mediated transcription in both mouse and human tissues. Short-read total RNA sequencing (RNA-seq) to profile nascent transcription reveals a global reduction in overall transcriptional activity/frequency in aged tissues, without apparent change in elongation rates.

Transcriptomic analysis reveals a shift toward preferential expression of short genes in aged tissues, with notable upregulation of short stress-response genes and downregulation of long neurodevelopmental genes in the aged mouse brain. These results are recapitulated by analysis of total RNA-seq data from human tissues. Leveraging long-read RNA-seq, we determine that the representation of aberrant mono-exonic and intron-retention splice isoforms is increased in the aged mouse brain.