AtXRN4 degrades mRNA in Arabidopsis and its substrates include selected miRNA targets.
Messenger RNA degradation is an essential step in gene expression that can be regulated by siRNAs or miRNAs. However, most of our knowledge of in vivo eukaryotic mRNA degradation mechanisms derives from Saccharomyces cerevisiae, which lacks miRNAs and RNAi capability. Using reverse genetic and microarray analyses, we have identified multiple substrates of AtXRN4, the Arabidopsis homolog of the major yeast mRNA degrading exoribonuclease, Xrn1p. Insertional mutation of AtXRN4 leads to accumulation of the 3' end of several mRNAs, in a manner that correlates with increased stability of the 3' end, and is reversed following complementation with AtXRN4. Moreover, 3' products of miRNA-mediated cleavage of SCARECROW-LIKE transcripts and several other miRNA target transcripts are among those that accumulate in xrn4 mutants. The demonstration that an Xrn1p homolog degrades mRNA in a multicellular eukaryote and contributes to the miRNA-mediated decay pathway of selected targets has implications for XRNs in other organisms.
Souret
Frédéric F
FF
Delaware Biotechnology Institute, University of Delaware, Newark 19711, USA.
Kastenmayer
James P
JP
Green
Pamela J
PJ
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000502:physiology; D005095:Exoribonucleases / Q000502:physiology*; D020869:Gene Expression Profiling; D020868:Gene Silencing; D016350:Leucine Zippers; D035683:MicroRNAs / Q000502:physiology*; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000502:physiology*; D030821:Plants, Genetically Modified; D020871:RNA Stability / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D035683:MicroRNAs; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; C100978:SCR protein, Arabidopsis; C418137:Xrn1 protein, plant; D005095:Exoribonucleases