Chemically synthesized short interfering RNAs (siRNAs) are able to induce an RNAi gene silencing pathway in cellular systems. Since their discovery, siRNA molecules have been considered convenient tools in functional genomics and potential therapeutics. Although numerous academic and commercial institutions conduct intensive research in the field of RNAi, there are still substantial limitations in application of this new, promising technology in medicine. Three major factors restricting therapeutic use of siRNAs are related to a limited cell membrane permeability, low nucleolytic cleavage resistance and off-target activity. Various chemical modifications have been introduced into siRNA duplexes to overcome obstacles mentioned above.

In the present studies we have evaluated thermodynamic and gene silencing activities of several chemically modified siRNAs. Modifications were introduced at functionally important domains including the 3’- and 5’-termini as well as the central part of a duplex. The gene silencing activity was screened in a dual fluorescence assay in HeLa cells (adopted from Chiu and Rana (1). Interesting functional properties were observed for duplexes conjugated (at the 3’-terminus in respect to the sense strand) with sugar residue designed to facilitate the cross-membrane transport. Furthermore, introduction of the non-cleavable internucleotide bond between the two 3’-terminal thymidine residues resulted in siRNA duplexes with improved exonucleolytic stability and maintained silencing activity. Finally, moderate silencing activity of siRNA has been improved by inducing “thermodynamic asymmetry” of the modified duplexes (2). This effect was achieved by introduction of a single modifications in terminal positions. Detailed thermodynamic characterization and gene silencing activity of these modified siRNA duplexes (containing 2‑thiouridine, pseudouridine, 2,6-diaminopurine-2’-deoxyribonucleotide or 2,6-diaminopurine-LNA nucleotide) will be presented.

Financial support from the State Committee for Scientific Research in Poland and ICGEB grant CRP/POL04-01 is highly appreciated.

1. Chiu, Y.L., Rana, T.M. RNAi in Human Cells: Basic structural and functional features of small interfering RNA. Mol. Cell 2002, 10: 549-561.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/10925 must be provided.

1. Lysophospholipids - mechanisms of action and perspectives of the use in therapy
2. Therapeutic applications of RNAi
3. Utrata ekspresji genu białka FHIT u osób z rodzinnym występowanie raka żołądka i infekcją Helicobacter pylori