Gunderson, S.I. (Samuel I.)
- Publications
- item.page.relationships.isContributorAdvisorOfPublication
- item.page.relationships.isContributorOfPublication
2 results
Search Results
Now showing 1 - 2 of 2
- Requirements for gene silencing mediated by U1 snRNA binding to a target sequence(Oxford University Press, 2008) Oswald, E. (Evelyn); Amin, V. (Vaibhav); Vera, M. (María); Gunderson, S.I. (Samuel I.); Abad, X. (Xabier); Fortes, P. (Puri); Jung, S.P. (Stephen P.); Romero, I. (Inés)U1 interference (U1i) is a novel method to block gene expression. U1i requires expression of a 5'-end-mutated U1 snRNA designed to base pair to the 3'-terminal exon of the target gene's pre-mRNA that leads to inhibition of polyadenylation. Here, we show U1i is robust (> or =95%) and a 10-nt target length is sufficient for good silencing. Surprisingly, longer U1 snRNAs, which could increase annealing to the target, fail to improve silencing. Extensive mutagenesis of the 10-bp U1 snRNA:target duplex shows that any single mismatch different from GU at positions 3-8, destroys silencing. However, mismatches within the other positions give partial silencing, suggesting that off-target inhibition could occur. The specificity of U1i may be enhanced, however, by the fact that silencing is impaired by RNA secondary structure or by splicing factors binding nearby, the latter mediated by Arginine-Serine (RS) domains. U1i inhibition can be reconstituted in vivo by tethering of RS domains of U1-70K and U2AF65. These results help to: (i) define good target sites for U1i; (ii) identify and understand natural cellular examples of U1i; (iii) clarify the contribution of hydrogen bonding to U1i and to U1 snRNP binding to 5' splice sites and (iv) understand the mechanism of U1i.
- Inhibiting expression of specific genes in mammalian cells with 5' end-mutated U1 small nuclear RNAs targeted to terminal exons of pre-mRNA(National Academy of Sciences, 2003) Guan, F. (Fei); Liu, P. (Peng); Cuevas, Y. (Yolanda); Prieto, J. (Jesús); Pentlicky, S. (Sara); Gunderson, S.I. (Samuel I.); Fortes, P. (Puri); Jung, S.P. (Stephen P.); Martinez-Chantar, M.L. (María Luz); Rowe, D. (David)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.