Genome-wide Identification and Quantitative Analysis of Cleaved tRNA Fragments Induced by Cellular Stress

Case Western Reserve University, United States
Journal of Biological Chemistry (Impact Factor: 4.57). 10/2012; 287(51). DOI: 10.1074/jbc.M112.371799
Source: PubMed


Certain stress conditions can induce cleavage of tRNAs around the anticodon loop via the use of the ribonuclease angiogenin. The cellular factors that regulate tRNA cleavage are not well known. In this study we used normal and eIF2α phosphorylation-deficient mouse embryonic fibroblasts (MEFs) and applied a microarray based methodology to identify and compare tRNA cleavage patterns in response to hypertonic stress, oxidative stress (arsenite) and treatment with recombinant angiogenin. In all three scenarios MEFs deficient in eIF2α phosphorylation showed a higher accumulation of tRNA fragments including those derived from initiator-tRNA(Met). We have shown that tRNA cleavage is regulated by the availability of angiogenin, its substrate (tRNA), the levels of the angiogenin inhibitor RNH1 and the rates of protein synthesis. These conclusions are supported by the following findings: (i) exogenous treatment with angiogenin or knockdown of RNH1 increased tRNA cleavage, (ii) tRNA fragment accumulation was higher during oxidative stress than hypertonic stress, in agreement with a dramatic decrease of RNH1 levels during oxidative stress and (iii) a positive correlation was observed between angiogenin-mediated tRNA cleavage and global protein synthesis rates. Identification of the stress-specific tRNA cleavage mechanisms and patterns will provide insights into the role of tRNA fragments in signaling pathways and stress related disorders.

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    • "They were later observed in unstressed human cells (Kawaji et al., 2008; Fu et al., 2009). However, their levels in resting cells are very low and often increase significantly only during stress conditions (Saikia et al., 2012). Our group and others detected tRNAderived small RNAs circulating in mouse and human bloodstream (Meiri et al., 2010; Dhahbi et al., 2013a,b, 2014; Dhahbi, 2014a). "
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    • "Angiogenin specifically stimulates the nuclear localization of TyrRS (Figure S1A available online), but not SerRS (seryl-tRNA synthetase) whose NLS was not found to be involved in tRNA binding (Xu et al., 2012). Consistent with previous reports (Fu et al., 2009; Hanada et al., 2013; Saikia et al., 2012), cellular tRNA Tyr appears to be intact during the angiogenin treatment (Figure S1B). However, angiogenin does have the capacity to cleave tRNA Tyr transcript in vitro (Figure S1C). "
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    • "Angiogenin - induced fragmentation of tRNAs to inhibit translation is a common response to various stress conditions ( Gold et al , 1963 ; Thompson et al , 2008 ; Fu et al , 2009 ; Yamasaki et al , 2009 ; Ivanov et al , 2011 ; Abbasi - Moheb et al , 2012 ; Saikia et al , 2012 ) . Although cellular factors regulating tRNA cleavage are largely unknown , "
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