Importance of translation and nonnucleolytic ago proteins for on-target RNA interference.
In animals, both siRNAs and miRNAs are thought to diminish protein synthesis from transcripts that are perfectly complementary by directing endonucleolytic cleavage where they anneal, thereby triggering rapid degradation of the entire message [1-4]. By contrast, partially complementary messages are downregulated by a combination of translational repression and accelerated decay caused by rapid poly(A) tail removal [3, 5-12]. Here we present evidence that translational repression can also make a substantial contribution to the downregulation of fully complementary messages by RNA interference. Unlike mRNA destabilization, this inhibitory effect on translation is greater for perfectly complementary elements located in the 3' untranslated region rather than in the protein-coding region. In addition to known disparities in their endonucleolytic activity [13, 14], the four Ago proteins with which siRNAs associate in humans differ significantly in their capacity to direct translational repression. As a result, the relative effect of siRNA on targets that are fully versus partially complementary is influenced by the comparative abundance of the three nonnucleolytic Ago proteins, causing this on-target/off-target ratio to vary in a cell-type-dependent manner because of the dissimilar tissue distribution of these proteins. These findings have important implications for the efficacy and specificity of RNA interference.
Wu
Ligang
L
Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, New York 10016, USA.
Fan
Jihua
J
Belasco
Joel G
JG
D060565:Argonaute Proteins; D002460:Cell Line; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D039642:Eukaryotic Initiation Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis; D006801:Humans; D014176:Protein Biosynthesis; D034622:RNA Interference / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000032:analysis
C115848:AGO1 protein, human; C466422:AGO2 protein, human; C517143:AGO3 protein, human; C517144:AGO4 protein, human; D060565:Argonaute Proteins; D015852:Eukaryotic Initiation Factor-2; D039642:Eukaryotic Initiation Factors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins
Nature. 2005 Feb 17;433(7027):769-73
15685193
Methods Mol Biol. 2004;257:135-54
14770003
Genes Dev. 2003 Feb 15;17(4):438-42
12600936
Cell. 2007 Mar 23;128(6):1105-18
17382880
Nat Biotechnol. 2003 Jun;21(6):635-7
12754523
RNA. 2004 Oct;10(10):1518-25
15337849
Cell. 1993 Dec 3;75(5):843-54
8252621
Cell. 1993 Dec 3;75(5):855-62
8252622
Mol Cell. 2007 Jun 8;26(5):611-23
17560368
Genes Dev. 2004 Jul 15;18(14):1655-66
15231716
Cell. 2007 Jun 15;129(6):1141-51
17524464
Cell. 2000 Mar 31;101(1):25-33
10778853
Science. 2006 Apr 7;312(5770):75-9
16484454
Mol Cell Biol. 2005 Nov;25(21):9198-208
16227573
Cell. 2005 Aug 26;122(4):553-63
16122423
Science. 2002 Sep 20;297(5589):2056-60
12154197
Mol Cell. 2004 Jul 23;15(2):185-97
15260970
Cell. 2007 Jul 27;130(2):287-97
17662943
Proc Natl Acad Sci U S A. 2003 Aug 19;100(17):9779-84
12902540
Nat Cell Biol. 2005 Dec;7(12):1261-6
16284623
Proc Natl Acad Sci U S A. 2004 Apr 20;101(16):6062-7
15075390
Science. 2004 Apr 23;304(5670):594-6
15105502
Science. 2004 Sep 3;305(5689):1437-41
15284456
Proc Natl Acad Sci U S A. 2006 Mar 14;103(11):4034-9
16495412