GSE108477
A nuclear export block triggers the decay of newly synthesized polyadenylated RNA
Genomes are promiscuously transcribed, necessitating mechanisms that facilitate the sorting of RNA for function or destruction. The polyA (pA) tail is one such distinguishing feature, which in the S. cerevisiae nucleus is bound by the Nab2p protein, yielding transcript protection. As Nab2p also contacts the main nuclear export factor Mex67p, we asked whether transport kinetics contributes to RNA sorting. Indeed, 3'end sequencing of newly transcribed pA+ RNAs demonstrates that nuclear depletion of Mex67p elicits their instant and global decay. A similar phenotype is evident upon inactivation of other export factors and proportional to the amount of nuclear pA+ RNA. Since RNA production is partially rescued by Nab2p over-expression, we propose that an export-block out-titrates Nab2p onto nuclear retained pA+ RNA, reducing the pool of Nab2p free to protect new transcripts. More generally, we suggest that nuclear RNA decay, negotiated by Nab2p availability, aids in balancing cellular transcript supply with demand. Overall design: pA+ RNA 3' end sequencing of total and 10min 4-thiouracil (4tU) labelled RNA from S. cerevisiae cells upon nuclear depletion of Mex67p or Nab2p using the anchor-away system for 15 minutes and undepleted control cells. RNA samples were collected in triplicate for each condition. Single replicates for negative controls not labeled with 4tU were processed in parallel.