Escaping nuclear decay: the significance of mRNA export for gene expression.

In this perspective, we discuss the regulatory impact of nuclear RNA export and decay on messenger RNA (mRNA) functionality. It is well established that control of protein-coding gene expression in eukaryotes employs the regulated production of mRNA, its intra-cellular transfer to cytoplasmic ribosomes and final transcript degradation. Despite a rich body of literature on these events, an involvement of nuclear RNA decay systems remains largely unexplored. Instead, nuclear RNA degradation is often considered a quality control precaution engaged primarily in ridding cells of aberrantly processed transcripts and spurious non-coding RNA. Recent research from human and budding yeast cells, however, demonstrates that even protein-coding transcripts fall prey to nuclear decay and that this is countered by their nuclear export. Here, we outline the potential of nuclear polyA-binding proteins in tuning levels of cellular mRNA to maintain transcript homeostasis.