Nonsense-mediated decay: paving the road for genome diversification.
The expression of protein-encoding genes is a complex process culminating in the production of mature mRNA and its translation by the ribosomes. The production of a mature mRNA involves an intricate series of processing steps. The majority of eukaryotic protein-encoding genes contain intron sequences that disrupt the protein-encoding frame, and hence have to be removed from immature mRNA prior to translation into protein. The mechanism involved in the selection of correct splice sites is incompletely understood. A considerable body of evidence suggests that the splicing machinery has suboptimal efficiency and fidelity leading to substantial processing inaccuracy. Here we discuss a recently published article that extends observations that cells rely on nonsense-mediated mRNA decay (NMD) to compensate for such suboptimal processing accuracy. Intriguingly these authors provide evidence for a strong selective pressure in favour of premature termination of mRNA translation in the event of intron retention. The analysis presented implies a positive role of NMD in transcript diversification through alternative splicing and suggest that this ancient surveillance mechanism may have co-evolved with intron acquisition born from the need for quality control of splicing patterns.
Sánchez-Sánchez
Francisco
F
Area de Genética, Facultad de Medicina/Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Albacete, Spain. francisco.ssanchez@uclm.es
Mittnacht
Sibylle
S
D018389:Codon, Nonsense; D019143:Evolution, Molecular; D016678:Genome; D007438:Introns / Q000235:genetics; D014176:Protein Biosynthesis / Q000235:genetics; D012326:RNA Splicing; D020871:RNA Stability / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012641:Selection, Genetic
D018389:Codon, Nonsense; D012333:RNA, Messenger