Translate the untranslated: excising as a novel post-splicing event

Maturing of a messenger RNA (mRNA) is a multi-way process producing mRNA variants through diverse splicing events, alternative polyadenylation, RNA editing, etc. Studying posttranscriptional processing of human cold-inducible RNA binding protein (CIRBP), we discovered yet another mechanism that could be added to this list. We named it excising, and it consists of low-accuracy post-splicing deletion of sequence regions of variable length. The main features of the excising process and putative members of corresponding multiprotein machinery were described with a series of cloning vectors and RNA-pulldown assay. Our results highlight a possible role of U-rich stretches and the proteins targeting such motifs in the discovered process. The discovered mechanism suggests the potential translation of 3-untranslated regions, which may be an adjuvant way of CIRBP activity inhibition or generation of structural and functional diversity.