Given the fact that both backbone systems do not mediate RNaseH activity, they seem particularly well suited for nuclear antisense applications. In order to compare the nuclear antisense properties of the two backbone systems we set out to study their performance side by side in a cyclophilin A CyPA splice assay. CyPA is a proline cis—trans isomerase that was initially discovered as the cellular ligand of the immunosuppressive drug cyclosporin A CsA Virions lacking CyPA show normal morphologies, package normal levels of viral proteins and RNAs, and exhibit normal reverse transcriptase activity 31 , However, the viral replication is blocked at some step after viral entry but before the reverse transcription starts The oligomers tc1 and tc2 were synthesized on universal solid support GlenResearch.

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Translational research Key Points All RNA-targeted therapeutic technologies exploit oligonucleotides that bind to target RNA, but they differ in their mechanism of action and produce different effects. Small interfering RNAs, antisense oligonucleotides and external guide sequences lead to enzyme-dependent degradation of targeted mRNA. Drugs involving these approaches are designed to reduce the level of harmful gene products such as viral or bacterial proteins or disease-promoting cellular proteins.

They could be useful against cancer as well as viral and bacterial infections, or used to prevent the accumulation of high levels of cholesterol in the bloodstream.

Splice-switching oligonucleotides are discussed in detail in this Review; these oligonucleotides redirect alternative splicing, repair defective RNA or restore the production of proteins that are missing because of genetic defects.

Compared to classical small-molecule drugs, it is much more difficult to achieve intracellular delivery with oligonucleotides; this is still a major issue for this class of drugs. The advantage of oligonucleotides is their high specificity, which results from sequence-specific base pairing to target RNA. Oligonucleotide-based drugs are now in advanced clinical trials for the treatment of cancer and Duchenne muscular dystrophy as well as for lowering high cholesterol levels.

Abstract Here, we discuss three RNA-based therapeutic technologies exploiting various oligonucleotides that bind to RNA by base pairing in a sequence-specific manner yet have different mechanisms of action and effects. RNA interference and antisense oligonucleotides downregulate gene expression by inducing enzyme-dependent degradation of targeted mRNA.

Through this mechanism, steric-blocking oligonucleotides can redirect alternative splicing, repair defective RNA, restore protein production or downregulate gene expression. Moreover, they can be extensively chemically modified to acquire more drug-like properties. The ability of RNA-blocking oligonucleotides to restore gene function makes them best suited for the treatment of genetic disorders. Positive results from clinical trials for the treatment of Duchenne muscular dystrophy show that this technology is close to achieving its clinical potential.


Nuclear antisense effects of neutral, anionic and cationic oligonucleotide analogs

O -MOE, morpholino and PNA oligomers To elucidate the influence of the backbone modification on the cellular uptake and antisense properties of different oligonucleotide analogs, the latter were tested in the EGFP assay. Results are reported as the FI. The index takes into account the percentage of fluorescent cells in the sample and the intensity of their fluorescence see Materials and Methods. Non-linear regression analysis of the dose response data revealed a theoretical limit of the FI specific for each backbone and delivery method. The results are summarized in Table 2.


RNA therapeutics: beyond RNA interference and antisense oligonucleotides

Kekinos The effects of the PNA oligomers were observed to be dependent on the number of l -lysine Lys residues at the C-terminus. Because the regulatory mechanism of asRNAs are found to be species specific, asRNAs can also be classified by species. Free Uptake of Oligonucleotides In scrape-loaded cells the transfer of oligonucleotides through the cellular and endosomal lipid bilayers is most likely bypassed. Cellular and molecular life sciences: In eukaryotic cells, DNA is tightly packed by histones.

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