Exaptive origins of regulated mRNA decay in eukaryotes
Hamid, Fursham Muhammad
Makeyev, Eugene V.
Date of Issue2016
School of Biological Sciences
Eukaryotic gene expression is extensively controlled at the level of mRNA stability and the mechanisms underlying this regulation are markedly different from their archaeal and bacterial counterparts. We propose that two such mechanisms, nonsense-mediated decay (NMD) and motif-specific transcript destabilization by CCCH-type zinc finger RNA-binding proteins, originated as a part of cellular defense against RNA pathogens. These branches of the mRNA turnover pathway might have been used by primeval eukaryotes alongside RNA interference to distinguish their own messages from those of RNA viruses and retrotransposable elements. We further hypothesize that the subsequent advent of “professional” innate and adaptive immunity systems allowed NMD and the motif-triggered mechanisms to be efficiently repurposed for regulation of endogenous cellular transcripts. This scenario explains the rapid emergence of archetypical mRNA destabilization pathways in eukaryotes and argues that other aspects of post-transcriptional gene regulation in this lineage might have been derived through a similar exaptation route.
© 2016 The Authors (published by WILEY Periodicals, Inc.) This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.