A link between mRNA turnover and RNA interference in Arabidopsis.
In RNA interference (RNAi), double-stranded RNA (dsRNA) triggers degradation of homologous messenger RNA. In many organisms, RNA-dependent RNA polymerase (RdRp) is required to initiate or amplify RNAi, but the substrate for dsRNA synthesis in vivo is not known. Here, we show that RdRp-dependent transgene silencing in Arabidopsis was caused by mutation of XRN4, which is a ribonuclease (RNase) implicated in mRNA turnover by means of decapping and 5'-3' exonucleolysis. When both XRN4 and the RdRp were mutated, the plants accumulated decapped transgene mRNA. We propose that mRNAs lacking a cap structure become exposed to RdRp to initiate or maintain RNAi.
Gazzani
S
S
Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.
Lawrenson
T
T
Woodward
C
C
Headon
D
D
Sablowski
R
R
D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics; D005095:Exoribonucleases / Q000235:genetics; D020868:Gene Silencing; D018398:Homeodomain Proteins / Q000235:genetics; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D012315:RNA Caps; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism*; D018749:RNA, Plant / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics
D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D010940:Plant Proteins; D012315:RNA Caps; D012333:RNA, Messenger; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; C097496:STM protein, Arabidopsis; C418137:Xrn1 protein, plant; D012324:RNA-Dependent RNA Polymerase; D005095:Exoribonucleases