Project description:Asterix/Gtsf1 has been previously been shown to be involved in the silencing of retrotransposons in animal germ cells through the piRNA pathway. Using eCLIP and a custom informatic pipeline, we found that Asterix/Gtsf1 binds directly to RNAs and preferentially interacts with tRNAs as a class. Given the role of tRNAs as primers for Long Terminal Repeat (LTR) transposons, this work implicates Asterix/Gtsf1 as exploiting tRNA dependence to identify transposon transcripts and promote piRNA silencing.
Project description:Asterix/Gtsf1 has been previously been shown to be involved in the silencing of retrotransposons in animal germ cells through the piRNA pathway. Using eCLIP and a custom informatic pipeline, we found that Asterix/Gtsf1 binds directly to RNAs and preferentially interacts with tRNAs as a class. Given the role of tRNAs as primers for Long Terminal Repeat (LTR) transposons, this work implicates Asterix/Gtsf1 as exploiting tRNA dependence to identify transposon transcripts and promote piRNA silencing.
Project description:Asterix/Gtsf1 has been previously been shown to be involved in the silencing of retrotransposons in animal germ cells through the piRNA pathway. Using eCLIP and a custom informatic pipeline, we found that Asterix/Gtsf1 binds directly to RNAs and preferentially interacts with tRNAs as a class. Given the role of tRNAs as primers for Long Terminal Repeat (LTR) transposons, this work implicates Asterix/Gtsf1 as exploiting tRNA dependence to identify transposon transcripts and promote piRNA silencing.
Project description:Asterix/Gtsf1 has been previously been shown to be involved in the silencing of retrotransposons in animal germ cells through the piRNA pathway. During early stages of purification of mouse Gtsf1 protein in Sf9 cells for structural studies, we found that the protein was co-purifying with endogenous nucleic acids. We first characterized those RNAs by next-generation sequencing (this dataset) and then later investigated its RNA-binding in more relevant cell culture systems. In each case, we found Asterix/Gtsf1 was binding tRNAs. Given the role of tRNAs as primers for Long Terminal Repeat (LTR) transposons, this work implicates Asterix/Gtsf1 as exploiting tRNA dependence to identify transposon transcripts and promote piRNA silencing.
Project description:The PIWI interacting RNA pathway is a small RNA silencing system that keeps selfish genetic elements such as transposons under control in animal gonads. Several lines of evidence indicate that nuclear PIWI family proteins guide transcriptional silencing of their targets, yet the composition of the underlying silencing complex is unknown. Here we demonstrate that the double CHHC zinc finger protein Gtsf1 is an essential factor for Piwi mediated transcriptional repression in Drosophila. Cells lacking Gtsf1 contain nuclear Piwi loaded with piRNAs, yet Piwi's silencing capacity is ablated. Gtsf1 interacts stably with a sub-population of nuclear Piwi and loss of Gtsf1 phenocopies loss of Piwi in terms of deregulation of transposons, loss of H3K9me3 marks at euchromatic transposon insertions and deregulation of genes in proximity to repressed transposons. We propose that only a small fraction of nuclear Piwi interacts productively with a target RNA, resulting in assembly of a silencing complex with Gtsf1 as one core component. impact of loss of DmGtsf1 on transcription and H3K9m3 in ovarian somatic cells (OSC)