Inhibiting expression of specific genes in mammalian cells with 5' end-mutated U1 small nuclear RNAs targeted to terminal exons of pre-mRNA.
Reducing or eliminating expression of a given gene is likely to require multiple methods to ensure coverage of all of the genes in a given mammalian cell. We and others [Furth, P. A., Choe, W. T., Rex, J. H., Byrne, J. C., and Baker, C. C. (1994) Mol. Cell. Biol. 14, 5278-5289] have previously shown that U1 small nuclear (sn) RNA, both natural or with 5' end mutations, can specifically inhibit reporter gene expression in mammalian cells. This inhibition occurs when the U1 snRNA 5' end base pairs near the polyadenylation signal of the reporter gene's pre-mRNA. This base pairing inhibits poly(A) tail addition, a key, nearly universal step in mRNA biosynthesis, resulting in degradation of the mRNA. Here we demonstrate that expression of endogenous mammalian genes can be efficiently inhibited by transiently or stably expressed 5' end-mutated U1 snRNA. Also, we determine the inhibitory mechanism and establish a set of rules to use this technique and to improve the efficiency of inhibition. Two U1 snRNAs base paired to a single pre-mRNA act synergistically, resulting in up to 700-fold inhibition of the expression of specific reporter genes and 25-fold inhibition of endogenous genes. Surprisingly, distance from the U1 snRNA binding site to the poly(A) signal is not critical for inhibition, instead the U1 snRNA must be targeted to the terminal exon of the pre-mRNA. This could reflect a disruption by the 5' end-mutated U1 snRNA of the definition of the terminal exon as described by the exon definition model.
Fortes
Puri
P
Department of Medicine, University of Navarra, Irunlarrea 1, Pamplona 31008, Spain. pfortes@unav.es
Cuevas
Yolanda
Y
Guan
Fei
F
Liu
Peng
P
Pentlicky
Sara
S
Jung
Stephen P
SP
Martínez-Chantar
Maria L
ML
Prieto
Jesús
J
Rowe
David
D
Gunderson
Samuel I
SI
D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D020029:Base Pairing; D001665:Binding Sites; D004357:Drug Synergism; D004742:Enhancer Elements, Genetic; D005347:Fibroblasts / Q000166:cytology; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics; D008156:Luciferases / Q000235:genetics; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012322:RNA Precursors / Q000037:antagonists & inhibitors* / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000235:genetics / Q000494:pharmacology*; D013539:Simian virus 40 / Q000235:genetics
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D012322:RNA Precursors; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA; D011061:Poly A; D008156:Luciferases