Increased intron retention is a post-transcriptional signature associated with progressive ageing and Alzheimer’s disease

Intron retention (IR) may affect gene expression and protein functions during development and age-onset diseases. However, it remains unclear if IR undergoes spatial or temporal changes during different stages of ageing or neurodegenerative disorders like Alzheimer’s disease (AD). By profiling mRNA species across different ages of Drosophila heads, we observed significant increase in the level of IR of many conserved genes as animals aged. Interestingly, distinct sets of genes are affected at different stages of adult fly life with IR occurring at several AD-associated genes in old adult. This suggests that alteration of proper protein functions by IR during ageing may lead to AD pathogenesis. Consistent with this notion, analyses of healthy human ageing brains and different AD datasets revealed similar increased aberrant IR activities in many AD-curated genes. Taken together, our data suggest that increase IR during ageing may be the driver for late-onset sporadic AD.