GSBS Student Publications


Dissecting RNA-interference pathway with small molecules

GSBS Program

Biochemistry & Molecular Pharmacology

Publication Date


UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Biochemistry and Molecular Pharmacology

Document Type



Life Sciences | Medicine and Health Sciences


RNA interference (RNAi) is a process whereby short-interfering RNAs (siRNA) silence gene expression in a sequence-specific manner. We have screened a chemical library of substituted dihydropteridinones and identified a nontoxic, cell permeable, and reversible inhibitor of the RNAi pathway in human cells. Biochemical and fluorescence resonance-energy transfer experiments demonstrated that one of the compounds, named ATPA-18, inhibited siRNA unwinding that occurred within 6 hr of siRNA transfection. Extracts prepared from ATPA-18-treated cells also exhibited a decrease in target RNA cleavage by activated RNA-induced silencing complex (RISC*). Interestingly, when activated RISC*, which harbors unwound antisense siRNA, was treated with ATPA-18 in vitro, target RNA cleavage was not affected, indicating that this compound inhibited siRNA unwinding or steps upstream of unwinding in the RNAi pathway. Our results also establish the timing of siRNA unwinding and show that siRNA helicase activity is required for RNAi. ATPA-18 analogs will therefore provide a new class of small molecules for studying RNAi mechanisms in a variety of model organisms and deciphering in vivo genetic functions through reverse genetics.

DOI of Published Version



Chem Biol. 2005 Jun;12(6):643-8. Link to article on publisher's site

Journal/Book/Conference Title

Chemistry and biology

Related Resources

Link to article in PubMed

PubMed ID