Amino abasic building blocks tune siRNA potency, off-target profile and stability
- Four pyrrolidine- and aminocyclopentane-based abasic phosphoramidites were made and placed at various siRNA positions.
- Sense-strand placement loosened the duplex and boosted silencing; one aminocyclopentane isomer was most potent, and a seed-region stereoisomer curbed miRNA-like off-targets.
- In mice, the potent variant improved liver knockdown and the seed variant cut off-target transcripts; a 3′-terminal unit added nuclease resistance and served as a conjugation handle.
💡 Points Based on the abstract
Destabilizing the duplex with an abasic unit is a known way to favor guide-strand loading, so the potency gain is expected; the interesting part is that seed off-target behavior flips with stereochemistry. Missing: a head-to-head against GNA or 2′-5′-linked seed modifications, and a test of whether the amino charge, not geometry, drives the effect. Worth trying next: the 3′ amine as a GalNAc attachment point in vivo.