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Topoisomerase 3B Interacts with RNAi Machinery to Promote Heterochromatin Formation and Transcriptional Silencing

ABSTRACT: Topoisomerases solve topological problems during DNA metabolism, but whether they participate in RNA metabolism remains unclear. Top3b represents a new family of topoisomerases carrying activities for both DNA and RNA. Here we show that in Drosophila, Top3b interacts biochemically and genetically with the RNAi-induced silencing complex (RISC) containing AGO2, p68 RNA helicase, and FMRP. Top3b and RISC mutants are defective in heterochromatin formation and transcriptional silencing by position-effect variegation assay; and this defect is suppressed in their double mutants. Moreover, both Top3b and AGO2 single mutants exhibit reduced heterochromatin protein HP1 in pericentric heterochromatin; and this reduction is also suppressed in their double mutant. Furthermore, expression of several genes and transposable elements (TEs) in heterochromatin is increased in the Top3b mutant. Notably, Top3b mutants defective in either RNA binding or catalytic activity are deficient in promoting HP1 recruitment and silencing of TEs. Our data suggest that Top3b acts as an RNA topoisomerase in siRNA-guided heterochromatin formation and transcriptional silencing. Grant title: An RNA topoisomerase complex interacts with Fragile X syndrome protein to promote neurodevelopment and maintain normal life-span. Grant ID: AG000689-08. Source: NIA/NIH

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE119185 | GEO | 2018/08/29

REPOSITORIES: GEO

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