The Birth of an Alternatively Spliced Exon: 3' Splice-Site Selection in Alu Exons

Abstract

Alu repetitive elements can be inserted into mature messenger RNAs via a splicing-mediated process termed exonization. To understand the molecular basis and the regulation of the process of turning intronic Alu s into new exons, we compiled and analyzed a data set of human exonized Alu s. We revealed a mechanism that governs 3′ splice-site selection in these exons during alternative splicing. On the basis of these findings, we identified mutations that activated the exonization of a silent intronic Alu .