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Topoisomerase 3β Interacts with RNAi Machinery to Promote Heterochromatin Formation and Transcriptional Silencing in Drosophila [ChIP-Seq]

ABSTRACT: Topoisomerases solve topological problems during DNA metabolism, but whether they participate in RNA metabolism remains unclear. Top3b represents a 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 similarly defective in heterochromatin formation and transcriptional silencing by position-effect variegation assay. Moreover, both Top3b and AGO2 mutants exhibit reduced levels of heterochromatin protein HP1 in pericentric heterochromatin. Furthermore, expression of several genes and transposable elements 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 transposable elements. Our data suggest that Top3b may act as an RNA topoisomerase in siRNA-guided heterochromatin formation and transcriptional silencing.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE119777 | GEO | 2018/09/12

REPOSITORIES: GEO

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Topoisomerase 3β Interacts with RNAi Machinery to Promote Heterochromatin Formation and Transcriptional Silencing in Drosophila [RNA-Seq]

Project description:Topoisomerases solve topological problems during DNA metabolism, but whether they participate in RNA metabolism remains unclear. Top3b represents a 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 similarly defective in heterochromatin formation and transcriptional silencing by position-effect variegation assay. Moreover, both Top3b and AGO2 mutants exhibit reduced levels of heterochromatin protein HP1 in pericentric heterochromatin. Furthermore, expression of several genes and transposable elements 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 transposable elements. Our data suggest that Top3b may act as an RNA topoisomerase in siRNA-guided heterochromatin formation and transcriptional silencing.

2018-09-12 | GSE119626 | GEO

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

Project description: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

2018-08-29 | GSE119185 | GEO

HP1 controls genomic targeting of four novel heterochromatin proteins in Drosophila

Project description:Heterochromatin is important for the maintenance of genome stability and regulation of gene expression, yet our knowledge of heterochromatin structure and function is incomplete. We identified four novel Drosophila heterochromatin proteins. Three of these proteins (HP3, HP4, and HP5) interact directly with HP1, while HP6 in turn binds to each of these three proteins. Immunofluorescence microscopy and genome-wide mapping of in vivo binding sites shows that all four proteins are components of heterochromatin. Depletion of HP1 causes redistribution of all four proteins, indicating that HP1 is essential for their heterochromatic targeting. Finally, mutants of HP4 and HP5 are dominant suppressors of position effect variegation, demonstrating their importance in heterochromatic gene silencing. These results indicate that HP1 acts as a docking platform for several mediator proteins that contribute to heterochromatin function. Keywords: DamID knock-down

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A dual-activity topoisomerase complex promotes both transcriptional activation and repression in response to starvation

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Casein kinase 1 and 2 phosphorylate a conserved cluster of Argonaute to control microRNA functionCasein kinase 1 and 2 phosphorylate a conserved cluster of Argonaute to control microRNA function

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PARN mediates 3'-end trimming of Argonaute-cleaved precursor microRNAs

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