5-ethynyluridine perturbs nuclear RNA metabolism to promote the nuclear accumulation of TDP-43 and other RNA binding proteins

We and others demonstrated that TDP-43 nuclear localization and function depend on the abundance of its nuclear pre-mRNA binding partners and its recruitment into large ribonucleoprotein complexes, which restricts TDP-43 nuclear efflux and maintains the critical nuclear pool of TDP-43.

To further investigate the interplay between TDP-43 and nascent RNAs, we set out to employ 5-ethynyluridine (5EU), a widely used uridine analog that enables ‘click chemistry’ labeling of nascent RNAs. Unexpectedly, 5EU induced the nuclear accumulation of TDP-43 and other nuclear RNA binding proteins (RBPs) and attenuated TDP-43 nuclear exit. RNA FISH demonstrated 5EU-induced nuclear accumulation of polyadenylated and GU-rich RNAs.