2 ',5 '-oligoadenylate-peptide nucleic acids (2-5A-PNAs) activate RNase L

To potentiate the 2-5A (2',5'-oligoadenylate)-antisense and peptide nucleic acid (PNA) approaches to regulation of gene expression, composite molecule s were generated containing both 2-5A and PNA moieties. 2-5A-PNA adducts we re synthesized using solid-phase techniques. Highly cross-linked polystyren e beads were functionalized with glycine tethered through a p-hydroxymethyl benzoic acid linker and the PNA domain of the chimeric oligonucleotide anal ogue was added by sequential elongation of the amino terminus with the mono methoxytrityl protected N-(2-aminoethyl)-N-(adenin-1-ylacetyl)glycinate. Tr ansition to the 2-5A domain was accomplished by coupling of the PNA chain t o dimethoxytrityl protected N-(2-hydroxyethyl)-N-(adenin-1-ylacetyl)glycina te, Finally, (2-cyanoethyl)-N,N-diisopropyl-4-O-(4,4-dimethoxytrityl)butylp hosphoramidite and the corresponding (2-cyanoethyl)-N, N-diisopropylphospho ramidite of 5-O-(4,4'-dimethoxytrityl)-3-O-(tert-butyldimethylsilyl)-N-6-be nzoyladenosine were the synthons employed to add the 2 butanediol phosphate linkers and the four 2',5'-linked riboadenylates. The 5'-phosphate moiety was introduced with 2-[[2-(4,4'-dimethoxytrityloxy)ethyl]sulfonyl]ethyl-(2- cyanoethyl)-N,N-diisopropylphosphoramidite. Deprotection with methanolic NH 3 and tetraethylammonium fluoride afforded the desired products, 2-5A-pnaA( 4), 2-5A-pnaA(8) and 2-5A-pnaA(12). When evaluated for their ability to cau se the degradation of two different RNA substrates by the 2-5A-dependent RN ase L, these new 2-5A-PNA conjugates were found to be potent RNase L activa tors. The union of 2-5A and PNA presents fresh opportunities to explore the biological and therapeutic implications of these unique approaches to anti sense. (C) 1999 Elsevier Science Ltd. All rights reserved.