Schmid M, Olszewski P, Pelechano V, Gupta I, Steinmetz LM, Jensen TH
Cell Reports 12 (1) 128-139 [2015-07-00; online 2015-07-00]
Polyadenylation of mRNA is a key step in eukaryotic gene expression. However, despite the major impact of poly(A) tails on mRNA metabolism, the precise roles of poly(A)-binding proteins (PABPs) in nuclear mRNA biogenesis remain elusive. Here, we demonstrate that rapid nuclear depletion of the S. cerevisiae PABP Nab2p leads to a global loss of cellular mRNA, but not of RNA lacking poly(A) tails. Disappearance of mRNA is a nuclear event, but not due to decreased transcription. Instead, the absence of Nab2p results in robust nuclear mRNA decay by the ribonucleolytic RNA exosome in a polyadenylation-dependent process. We conclude that Nab2p is required to protect early mRNA and therefore constitutes a crucial nuclear mRNA biogenesis factor.