Off-target cellular messenger RNAs with seed-region complementarity

Off-target cellular messenger RNAs (mRNAs) with seed-region complementarity represent a major class of unintended targets for RNA interference (RNAi) therapeutics, such as small interfering RNAs (siRNAs) and short hairpin RNAs (shRNAs). This phenomenon occurs when the 'seed region' of the siRNA guide strand—typically nucleotides 2 through 8—binds to complementary sequences in the 3' untranslated regions (UTRs) of non-target mRNAs (Jackson et al., 2003, Nature Biotechnology). This interaction mimics the natural mechanism of microRNAs (miRNAs), leading to the degradation or translational repression of these unintended transcripts (Birmingham et al., 2006, Nature Methods). Because a single 7-nucleotide seed sequence can be present in hundreds of different cellular mRNAs, a single siRNA can potentially perturb the expression of many genes simultaneously. Such off-target effects are a primary concern in drug safety, as they can lead to cellular toxicity, altered metabolic pathways, or hepatotoxicity in clinical settings (Janas et al., 2018, Nature Communications). To mitigate these risks, researchers employ chemical modifications, such as 2'-O-methyl substitutions at position 2 of the guide strand, to reduce the binding affinity of the seed region while maintaining on-target potency. Understanding and predicting these interactions through bioinformatics and transcriptomic profiling is essential for the design of safe and specific RNA-based medicines.

Other names

Seed-mediated off-target effectsmiRNA-like off-target effectssiRNA off-target effectsUnintended mRNA silencing

Seed-mediated RNA interference (RNAi) leading to mRNA degradation or translational repression