Tandem alternative polyadenylation events of genes in non-eosinophilic nasal polyp tissue identified by high-throughput sequencing analysis

Nasal polyps (NP) is highly associated with the disorder of immune cells. Alternative polyadenylation (APA) produces mRNA isoforms with different length of 3'-untranslated region (UTR) and regulates gene expression. It has been proven that this APA-mediated regulation of 3'UTR length is an immune-associated phenomenon. The aim of this study was to investigate the genome-wide alternative tandem 3'UTR length switching events in non-eosinophilic nasal polyp tissue. Thirteen patients diagnosed as having non-eosinophilic nasal polyps were included in this study. Nasal polyp tissue and control mucosa were collected during surgery. The 3' end library of cDNA was constructed. The recovered libraries were sequenced with second sequencing technology, and the sequencing data were analyzed by an in-house bioinformatics pipeline. Tandem 3'UTR length switching between samples was detected by a test of linear trend alternative to independence. We found a significant alteration in the tandem 3'UTR length in 1,920 genes in nasal polyp samples. Functional annotation results showed that several gene ontology (GO) terms were enriched in the list of genes with switched APA sites, including regulation of transcription, macromolecule catabolic localization and mRNA processing. The results suggested that APA-mediated alternative 3'UTR regulation plays an important role in the post-transcriptional regulation of gene expression in non-eosinophilic nasal polyps.