Nuclear RNA Regulation by XRN2 and XTBD Family Proteins

Abstract

XRN2 is a 5'-to-3' exoribonuclease that is predominantly localized in the nucleus. By degrading or trimming various classes of RNA, XRN2 contributes to essential processes in gene expression such as transcription termination and ribosome biogenesis. Despite limited substrate specificity in vitro, XRN2 targets a specific subset of RNA by interacting with other proteins in cells. Here we review the functions of proteins that have an evolutionarily conserved XRN2-binding domain, XTBD. These proteins modulate activity of XRN2 by stabilizing it, controlling its subcellular localization or recruiting it to specific RNA targets, and thereby impact on various cellular processes. XRN2 and XTBDRibonucleases control cellular RNA levels by degrading mature RNA or by processing RNA precursors for maturation, thereby supporting gene regulation. They also contribute to the maintenance of cells' health by eliminating useless or potentially harmful RNA such as aberrant RNA species and the remnants of RNA biogenesis (Wolin and Maquat, 2019).XRN2 is an evolutionarily conserved 5'-to-3' exoribonuclease that is distributed in two compartments of the nucleus: the nucleoplasm and the nucleolus. Since original identification as ribonucleic acid trafficking protein 1 (Rat1) in Saccharomyces cerevisiae