Lessons from non-canonical splicing

Advances in transcriptomics and analysis have identified thousands of previously unknown non-canonical splicing events. In this Review, the authors discuss the mechanisms and functions of these events and their roles in a variety of diseases. They explain how non-canonical splicing mechanisms can be targeted or exploited for therapeutic strategies. Recent improvements in experimental and computational techniques that are used to study the transcriptome have enabled an unprecedented view of RNA processing, revealing many previously unknown non-canonical splicing events. This includes cryptic events located far from the currently annotated exons and unconventional splicing mechanisms that have important roles in regulating gene expression. These non-canonical splicing events are a major source of newly emerging transcripts during evolution, especially when they involve sequences derived from transposable elements. They are therefore under precise regulation and quality control, which minimizes their potential to disrupt gene expression. We explain how non-canonical splicing can lead to aberrant transcripts that cause many diseases, and also how it can be exploited for new therapeutic strategies.