Nonsense-mediated mRNA Decay in Saccharomyces cerevisiae: A Quality Control Mechanism That Degrades Transcripts Harboring Premature Termination Codons

Messenger RNA (mRNA) turnover is a process thatplays a major role in the control of gene expression. Although transcription serves as the initial regulatory event,it is clear that mRNA degradation can also influence cellular growth and differentiation. In eukaryotic cells,mRNA decay rates vary extensively. In S. cerevisiae, forexample, some mRNAs have half-lives of about 60 minutes, and very unstable messages exhibit half-lives asshort as 1 minute (Peltz and Jacobson 1993). Severalstudies have demonstrated that the decay rates of certainmRNAs can be modulated in response to environmentalsignals (Ross 1995; Gonzalez and Martin 1996; Scheffleret al. 1998). Furthermore, the expression of many highlyregulated transcripts involved in cellular proliferation anddifferentiation is controlled by mRNA stability. Alteredcontrol of their mRNA degradation rates can lead to aberrant gene expression and disease (Raymond et al. 1989;Taylor et al. 1996). Therefore, the importance of mRNAturnover to the regulation of gene expression has gainedmuch interest in recent years, and the structures andmechanisms that control mRNA decay rates are currentlyunder investigation (for review, see McCarthy 1999; Jacobson and Peltz 2000)...