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Molecular and Cellular Biology, April 2001, p. 2815-2825, Vol. 21, No. 8
Department of Genetics and Developmental
Biology, University of Connecticut Health Center, Farmington,
Connecticut 06030,1 and Department of
Molecular Biology and Biochemistry, Rutgers University, Piscataway,
New Jersey 088542
Received 3 August 2000/Returned for modification 28 September
2000/Accepted 17 January 2000
Although the primary function of U1 snRNA is to define the 5'
donor site of an intron, it can also block the accumulation of a
specific RNA transcript when it binds to a donor sequence within its
terminal exon. This work was initiated to investigate if this property
of U1 snRNA could be exploited as an effective method for
inactivating any target gene. The initial 10-bp segment of U1
snRNA, which is complementary to the 5' donor sequence, was
modified to recognize various target mRNAs (chloramphenicol acetyltransferase [CAT],
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.8.2815-2825.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Reduction of Target Gene Expression by a Modified U1
snRNA
-galactosidase, or green fluorescent protein [GFP]). Transient cotransfection of reporter genes and appropriate U1 antitarget vectors resulted in >90% reduction of transgene expression. Numerous sites within the CAT transcript were
suitable for targeting. The inhibitory effect of the U1 antitarget vector is directly related to the hybrid formed between the U1 vector
and target transcripts and is dependent on an intact
70,000-molecular-weight binding domain within the U1 gene. The effect
is long lasting when the target (CAT or GFP) and U1 antitarget
construct are inserted into fibroblasts by stable transfection. Clonal
cell lines derived from stable transfection with a pOB4GFP target
construct and subsequently stably transfected with the U1 anti-GFP
construct were selected. The degree to which GFP fluorescence was
inhibited by U1 anti-GFP in the various clonal cell lines was assessed
by fluorescence-activated cell sorter analysis. RNA analysis
demonstrated reduction of the GFP mRNA in the nuclear and cytoplasmic
compartment and proper 3' cleavage of the GFP residual transcript.
An RNase protection strategy demonstrated that the transfected U1
antitarget RNA level varied between 1 to 8% of the endogenous U1
snRNA level. U1 antitarget vectors were demonstrated to have
potential as effective inhibitors of gene expression in intact cells.
*
Corresponding author. Mailing address: Department of
Genetics and Developmental Biology, Mail Code 1231, University of
Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030. Phone: (860) 679-2324. Fax: (860) 679-8345. E-mail:
drowe{at}nso1.uchc.edu.
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