Effect of retained introns on the coding potential of RNA molecules in human leukemia cells

Intron retention is a mode of alternative splicing in which at least one intron is retained in mature RNA molecules. The inclusion of an intron sequence within the coding region of the mRNA can change the structure, properties and, in some cases, the functions of the corresponding protein. Furthermore, some of these altered proteins can be immunogenic and are considered as potential targets for the treatment of a number of diseases. In general, however, the effect of intron retention on the coding potential of RNA molecules remains poorly studied. This paper presents the results of a combined transcriptomic-proteomic study of 3540 intron sequences retained in mature RNA molecules of genes that are active in human leukemia cells. The introns were classified according to their coding potential and seven possible ways in which intron retention can influence the subsequent translation of the corresponding transcripts were described. A total of 56 translation-capable intronic sequences were identified, and 3 of them produce previously unknown polypeptides.