Thompson Debrah M, Parker Roy
Department of Molecular and Cellular Biology, and Howard Hughes Medical Institute, University of Arizona, Tucson, AZ 85721, USA.
J Cell Biol. 2009 Apr 6;185(1):43-50. doi: 10.1083/jcb.200811119. Epub 2009 Mar 30.
The cellular response to stress conditions involves a decision between survival or cell death when damage is severe. A conserved stress response in eukaryotes involves endonucleolytic cleavage of transfer RNAs (tRNAs). The mechanism and significance of such tRNA cleavage is unknown. We show that in yeast, tRNAs are cleaved by the RNase T2 family member Rny1p, which is released from the vacuole into the cytosol during oxidative stress. Rny1p modulates yeast cell survival during oxidative stress independently of its catalytic ability. This suggests that upon release to the cytosol, Rny1p promotes cell death by direct interactions with downstream components. Thus, detection of Rny1p, and possibly its orthologues, in the cytosol may be a conserved mechanism for assessing cellular damage and determining cell survival, analogous to the role of cytochrome c as a marker for mitochondrial damage.
细胞对应激条件的反应涉及在损伤严重时在存活或细胞死亡之间做出抉择。真核生物中一种保守的应激反应涉及转移RNA（tRNA）的核酸内切酶切割。这种tRNA切割的机制和意义尚不清楚。我们发现，在酵母中，tRNA被核糖核酸酶T2家族成员Rny1p切割，在氧化应激期间，Rny1p从液泡释放到细胞质中。Rny1p在氧化应激期间调节酵母细胞存活，与其催化能力无关。这表明，释放到细胞质后，Rny1p通过与下游成分的直接相互作用促进细胞死亡。因此，在细胞质中检测到Rny1p及其可能的直系同源物可能是评估细胞损伤和确定细胞存活的一种保守机制，类似于细胞色素c作为线粒体损伤标志物的作用。
