RNAi triggered by symmetrically transcribed transgenes in Drosophila melanogaster.
Specific silencing of target genes can be induced in a variety of organisms by providing homologous double-stranded RNA molecules. In vivo, these molecules can be generated either by transcription of sequences having an inverted-repeat (IR) configuration or by simultaneous transcription of sense-antisense strands. Since IR constructs are difficult to prepare and can stimulate genomic rearrangements, we investigated the silencing potential of symmetrically transcribed sequences. We report that Drosophila transgenes whose sense-antisense transcription was driven by two convergent arrays of Gal4-dependent UAS sequences can induce specific, dominant, and heritable repression of target genes. This effect is not dependent on a mechanism based on homology-dependent DNA/DNA interactions, but is directly triggered by transcriptional activation and is accompanied by specific depletion of the endogenous target RNA. Tissue-specific induction of these transgenes restricts the target gene silencing to selected body domains, and spreading phenomena described in other cases of post-transcriptional gene silencing (PTGS) were not observed. In addition to providing an additional tool useful for Drosophila functional genomic analysis, these results add further strength to the view that events of sense-antisense transcription may readily account for some, if not all, PTGS-cosuppression phenomena and can potentially play a relevant role in gene regulation.
Giordano
Ennio
E
Dipartimento di Genetica, Biologia Generale e Molecolare, Università di Napoli, Napoli 80134, Italia. giordano@biol.dgbm.unina.it
Rendina
Rosaria
R
Peluso
Ivana
I
Furia
Maria
M
D000818:Animals; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006836:Hydro-Lyases; D019476:Insect Proteins / Q000502:physiology; D009687:Nuclear Proteins; D012330:RNA, Double-Stranded / Q000235:genetics; D016601:RNA-Binding Proteins; D014158:Transcription, Genetic; D019076:Transgenes
D029721:Drosophila Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; D012330:RNA, Double-Stranded; D016601:RNA-Binding Proteins; D006836:Hydro-Lyases; C119240:Nop60B protein, Drosophila