Chemical synthesis of site-specifically 2'-azido-modified RNA and potential applications for bioconjugation and RNA interference.

Michaela Aigner,Jessica Steger,Katja Fauster,Ronald Micura,Klaus Bister,Markus Hartl

doi:10.1002/cbic.201000646

Abstract

One of the most important scientific discoveries in the recent past concerns RNA interference (RNAi), which is a post-transcriptional gene-silencing mechanism induced by small interfering RNA (siRNA) and micro-RNA (miRNA).[1] RNAi has opened up new avenues in the development of siRNA and miRNA as therapeutic agents for various diseases.[2] The reason for the large number of reports about chemically modified siRNA is their potential to enhance nuclease resistance, to prevent immune activation, to decrease off-target effects, and to improve pharmacokinetic and pharmacodynamic properties, all of which are important for the application of siRNA as therapeutic agents.[3] Another substantial challenge is siRNA delivery, because these reagents cannot easily traverse cell membranes because of their size and negative charge.[4] To date, the most promising therapeutic approach based on RNAi involves chemically modified siRNA that can resolve some of the issues mentioned above.

Highlights

One of the most important scientific discoveries in the recent past concerns RNA interference (RNAi), which is a post-transcriptional gene-silencing mechanism induced by small interfering RNA and micro-RNA.[1]
Chemical small interfering RNA (siRNA) modifications belong to four classes—backbone, ribose, nucleobase, and terminal modifications—with ribose modifications being the most common.[2b]. Structurally simple alterations, such as 2’-OCH3 and 2’-F, lead to significantly enhanced performance of siRNA with diverse target genes, provided that they are positioned in a site-specific manner.[3]
The guide strand is incorporated into the crucial functional particle, the RNA-induced silencing complex (RISC); RNA recognition and discrimination from non-native counterparts is very stringent.[6]

Summary

Introduction

One of the most important scientific discoveries in the recent past concerns RNA interference (RNAi), which is a post-transcriptional gene-silencing mechanism induced by small interfering RNA (siRNA) and micro-RNA (miRNA).[1]. It is even more surprising that, to the best of our knowledge, the solid-phase chemical synthesis of 2’-azido-modified RNA has not yet been described.[8] The prospect of potential siRNA applications, and of promising applications in modern bioconjugation chemistry (such as Staudinger ligation and click chemistry)[9] prompted us to take up the challenge of synthesizing these RNA derivatives (Scheme 1).

Results

Conclusion