Human cytosolic tRNase ZL can downregulate gene expression through miRNA

A long form of tRNase Z (tRNase Z(L)) can cleave any target RNA at any desired site under the direction of artificial small guide RNA including similar to 25-nucleotide hook-shaped RNA. Here we show that human miR-103 can form a hook structure to guide target RNA cleavage by human cytosolic tRNase Z(L) in vitro. In vivo analyses using luciferase mRNAs modified to contain miR-103 target sequences in their 3' untranslated regions indicated that miR-103 downregulates gene expression through directing mRNA cleavage by tRNase Z(L). The present data suggest the possibility that human cytosolic tRNase ZL modulates gene expression through a subset of microRNAs in the cells. (C) 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.