Differential roles of human Dicer-binding proteins TRBP and PACT in small RNA processing

摘要: During RNA interference and related gene regulatory pathways, the endonuclease Dicer cleaves precursor molecules to produce microRNAs (miRNAs) short interfering RNAs (siRNAs). Human cells encode a single enzyme that can associate with two different double-stranded (dsRNA)-binding proteins, protein activator of PKR (PACT) trans-activation response RNA-binding (TRBP). However, functional redundancy or differentiation PACT TRBP in miRNA siRNA biogenesis is not well understood. Using reconstituted system, we show here have distinct effects on Dicer-mediated dsRNA processing. In particular, found complex inhibits processing pre-siRNA substrates when compared Dicer-TRBP complex. addition, non-redundant production different-sized miRNAs (isomiRs), which turn alter target-binding specificities. Experiments using chimeric versions suggest N-terminal domains each confer observed differences substrate recognition behavior Dicer-dsRNA-binding complexes. These results support conclusion humans, Dicer-associated dsRNA-binding proteins are important factors contribute both cleavage specificity during production.