A novel vector-based RNAi method using mouse U6 promoter-driven shRNA expression in the filamentous fungus Blakeslea trispora.

PURPOSE: There are several studies on the use of RNA interference (RNAi) for gene function analysis in fungi. However, most studies on filamentous fungi are based on in vitro-transcribed or -synthesized small interfering RNA (siRNA), and only a few have reported the use of vector-based RNAi. Here we want to develop and evaluate a new vector-based RNAi method using the mouse U6 promoter to drive short hairpin RNA (shRNA) expression in the filamentous fungi. METHODS: Molecular techniques were employed to develop and evaluate a new vector-based RNAi method using the mouse U6 promoter to drive short hairpin RNA (shRNA) expression in the filamentous fungus Blakeslea trispora. RESULTS: We characterized the mouse U6 promoter and utilized it for the expression of shRNA in B. trispora. Using real-time polymerase chain reaction and western blotting analyses, we confirmed the decrease in the mRNA and protein expression of carRA, respectively, in cells transformed with the mouse U6 promoter-driven shRNA expression vector. This indicated that the shRNA was transcribed from the mouse U6 promoter and correctly processed into siRNA and that the mouse U6 promoter exhibited transcription ability in the filamentous fungi. CONCLUSIONS: The results suggest that the mouse U6 promoter that drives the expression of shRNA vectors may serve as a novel tool for RNAi induction in filamentous fungi.