Poison Exon
Poison exons (PEs); also called premature termination codon (PTC) exons or nonsense-mediated decay (NMD) exons] are a class of Alternative splicing#Modes, cassette exons that contain PTCs. Inclusion of a PE in a transcript targets the transcript for degradation via NMD. PEs are generally highly conserved elements of the genome and are thought to have important regulatory roles in biology. Targeting PE inclusion or exclusion in certain transcripts is being evaluated as a therapeutic strategy. Discovery In 2002, a model termed regulated unproductive splicing and translation (RUST) was proposed based on the finding that many (~one-third) alternatively spliced transcripts contain PEs. In this model, coupling alternative splicing to NMD (AS-NMD) is thought to tune transcript levels to regulate protein expression. Alternative splicing may also lead to NMD via other pathways besides PE inclusion, e.g., intron retention. PEs were initially characterized in RNA-binding proteins from ...
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