부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jmb.2005.03.012 Byline: Marita Overhoff (a), Martina Alken (b), Rosel Kretschmer-Kazemi Far (a), Marc Lemaitre (c), Bernard Lebleu (b), Georg Sczakiel (a), Ian Robbins (b) Abstract: The efficiency with which small interfering RNAs (siRNAs) down-regulate specific gene expression in living cells is variable and a number of sequence-governed, biochemical parameters of the siRNA duplex have been proposed for the design of an efficient siRNA. Some of these parameters have been clearly identified to influence the assembly of the RNA-induced silencing complex (RISC), or to favour the sequence preferences of the RISC endonuclease. For other parameters, it is difficult to ascertain whether the influence is a determinant of the siRNA per se, or a determinant of the target RNA, especially its local structural characteristics. In order to gain an insight into the effects of local target structure on the biological activity of siRNA, we have used large sets of siRNAs directed against local targets of the mRNAs of ICAM-1 and survivin. Target structures were classified as accessible or inaccessible using an original, iterative computational approach and by experimental RNase H mapping. The effectiveness of siRNA was characterized by measuring the IC.sub.50 values in cell culture and the maximal extent of target suppression. Mean IC.sub.50 values were tenfold lower for accessible local target sites, with respect to inaccessible ones. Mean maximal target suppression was improved. These data illustrate that local target structure does, indeed, influence the activity of siRNA. We suggest that local target screening can significantly improve the hit rate in the design of biologically active siRNAs. Author Affiliation: (a) Universitat zu Lubeck, Institut fur Molekulare Medizin, Ratzeburger Allee 160, D-23538 Lubeck, Germany (b) UMR 5124 CNRS, Laboratoire des Defenses Antivirales et Antitumorales, Universite Montpellier II, 34095 Montpellier Cedex 5, France (c) EUROGENTEC S.A., Liege Science Park, B-4102 Seraing, Belgium Article Note: (miscellaneous) Edited by J. Karn