celltype-specificdeliveryofsirnaswithaptamer-sirnachimeras.doc

Cell type-specific delivery of siRNAs with aptamer-siRNA chimeras Sullenger, B. A. et al Duke Center for Translational Research, Duke University Nature Biotechnology, 2006, 24, 1005 Julia Vargas November 25th, 2006 Julia Vargas @ Wipf Group 1 11/25/2006Discovery of RNAi ( 2006 Nobel Prize in Physiology or Medicine “for their discovery of RNA interference – gene silencing by double-stranded RNA” Andrew Z. Fire Stanford University Craig C. Mello University of Massachusetts Nobel Prize: physiology or medicine, reverse side. [Photograph]. Retrieved November 12, 2006, from Encyclopedia Britannica Online: /eb/art-18048 Julia Vargas @ Wipf Group 2 11/25/2006Discovery of RNAi (Regulation of gene expression in C. Elegans ? dsRNA induces highly specific gene silencing ? Silencing triggers: - exogenously induced dsRNA, RNA viruses, transposons, endogenous short dsRNAs ? Posttranscriptional cytoplasmic mechanism ? Systemic Silencing ? Effects first generation progeny /nobel_prizes/medicine/laureates/2006/adv.html Julia Vargas @ Wipf Group 3 11/25/2006RNA interference ? dsRNA when injected into cell is cleaved by Dicer - A Class 3 RNase III endonuclease Structural Features: ? 21-25 nt sequence, composed of duplex (19-23 bp) ? 3’ overhang, 2-nt segment ? 5’-phosphate and 3’-hydroxyl termini Nat. Struct. Biol. 3, 214 (2004). Julia Vargas @ Wipf Group 4 11/25/2006Mechanistic Model ? dsRNA recognized by Dicer ? Endonucleolytic cleavage ? siRNA-RISC complex targets homologous mRNAs Nature. 418, 244 (2002) Julia Vargas @ Wipf Group 5 11/25/2006RNAi Therapeutics Advantages: ? Target-gene specificity ? Low immunogenicity ? Simplicity of design/testing - easily synthesized, large scale - low cost ? Amenable to chemical modifications ? Size: aptamer vs antibody 15 kDa 150 kDa CEN. 2006, 84(46), 16-23 Julia Vargas @ Wipf Group 6 11/25/2006Cell type-specific delivery of siRNAs ? RNA-based approach for specific delivery of siRNA ? Exploit structural potential of RNA to