Aberrant methylation of tRNAs links cellular stress to neuro‐developmental disorders

作者：Sandra Blanco, Sabine Dietmann, Joana V. Flores, Shobbir Hussain, Claudia Kutter, Peter Humphreys, Margus Lukk, Patrick Lombard, Lucas Treps, Martyna Popis, Stefanie Kellner, Sabine M. Hölter, Lillian Garrett, Wolfgang Wurst, Lore Becker, Thomas Klopstock, Helmut Fuchs, Valérie Gailus‐Durner, Martin Hrabě de Angelis, Ragnhildur Thóra Káradóttir, Mark Helm, Jernej Ule, Joseph G. Gleeson, Duncan T. Odom, Michaela Frye · 发表于：The EMBO Journal · 年份：2014 · DOI：10.15252/embj.201489282 · 被引用次数：645 · 研究领域：RNA modifications and cancer、Epigenetics and DNA Methylation、Cancer-related molecular mechanisms research

Mutations in the cytosine-5 RNA methyltransferase NSun2 cause microcephaly and other neurological abnormalities in mice and human. How post-transcriptional methylation contributes to the human disease is currently unknown. By comparing gene expression data with global cytosine-5 RNA methylomes in patient fibroblasts and NSun2-deficient mice, we find that loss of cytosine-5 RNA methylation increases the angiogenin-mediated endonucleolytic cleavage of transfer RNAs (tRNA) leading to an accumulation of 5' tRNA-derived small RNA fragments. Accumulation of 5' tRNA fragments in the absence of NSun2 reduces protein translation rates and activates stress pathways leading to reduced cell size and increased apoptosis of cortical, hippocampal and striatal neurons. Mechanistically, we demonstrate that angiogenin binds with higher affinity to tRNAs lacking site-specific NSun2-mediated methylation and that the presence of 5' tRNA fragments is sufficient and required to trigger cellular stress responses. Furthermore, the enhanced sensitivity of NSun2-deficient brains to oxidative stress can be rescued through inhibition of angiogenin during embryogenesis. In conclusion, failure in NSun2-mediated tRNA methylation contributes to human diseases via stress-induced RNA cleavage.