Delivery of steric block morpholino oligomers by (R-X-R)4 peptides: structure-activity studies.

TitleDelivery of steric block morpholino oligomers by (R-X-R)4 peptides: structure-activity studies.
Publication TypeJournal Article
Year of Publication2008
AuthorsAbes R, Moulton HM, Clair P, Yang S-T, Abes S, Melikov K, Prevot P, Youngblood DS, Iversen PL, Chernomordik LV, Lebleu B
JournalNucleic acids research
Volume36
Issue20
Pagination6343-54
Date Published2008 Nov
ISSN1362-4962
Keywords6-Aminocaproic Acid, Amides, Arginine, Biological Transport, Endosomes, Hela Cells, Heparin, Humans, Hydrogen-Ion Concentration, Hydrophobic and Hydrophilic Interactions, Liposomes, Morpholines, Oligonucleotides, Peptides, Phosphoric Acids, Stereoisomerism, Structure-Activity Relationship
Abstract

Redirecting the splicing machinery through the hybridization of high affinity, RNase H- incompetent oligonucleotide analogs such as phosphoramidate morpholino oligonucleotides (PMO) might lead to important clinical applications. Chemical conjugation of PMO to arginine-rich cell penetrating peptides (CPP) such as (R-Ahx-R)(4) (with Ahx standing for 6-aminohexanoic acid) leads to sequence-specific splicing correction in the absence of endosomolytic agents in cell culture at variance with most conventional CPPs. Importantly, (R-Ahx-R)(4)-PMO conjugates are effective in mouse models of various viral infections and Duchenne muscular dystrophy. Unfortunately, active doses in some applications might be close to cytotoxic ones thus presenting challenge for systemic administration of the conjugates in those clinical settings. Structure-activity relationship studies have thus been undertaken to unravel CPP structural features important for the efficient nuclear delivery of the conjugated PMO and limiting steps in their internalization pathway. Affinity for heparin (taken as a model heparan sulfate), hydrophobicity, cellular uptake, intracellular distribution and splicing correction have been monitored. Spacing between the charges, hydrophobicity of the linker between the Arg-groups and Arg-stereochemistry influence splicing correction efficiency. A significant correlation between splicing correction efficiency, affinity for heparin and ability to destabilize model synthetic vesicles has been observed but no correlation with cellular uptake has been found. Efforts will have to focus on endosomal escape since it appears to remain the limiting factor for the delivery of these splice-redirecting ON analogs.

DOI10.1093/nar/gkn541
Alternate JournalNucleic Acids Res.