Project description:We discovered that the splicing factor Sex lethal (Sxl) also associates strongly with chromatin and that this association is not linked to its RNA-binidng capacity, nor its N- or C-terminal domains. We also found that Sxl is recruited to chromatin by the RNA polymerase III subunt Polr3E.
Project description:The RNA-binding protein sex-lethal (Sxl) is classically defined as a master regulator of sex determination and RNA splicing in Drosophila melanogaster. However, this role is not conserved in all species and functions beyond this canonical pathway remain largely unexplored. Here, we uncover a splicing-independent function for Sxl at the chromatin level in the Drosophila brain. Using Targeted DamID (TaDa) profiling in larval neurons, we identify widespread recruitment of Sxl to promoter regions, independent of sex and RNA binding activity. Notably, Sxl chromatin occupancy exhibits near-complete overlap with Polr3E (RPC37), an RNA Polymerase III subunit, with Sxl binding abolished upon Polr3E knockdown. Depletion of Sxl in mature male neurons equally induces widespread transcriptional changes, particularly in metabolic genes, and improves negative geotaxis during ageing, phenotypes that closely mirror Polr3E knockdown. Conversely, overexpression of SxlRAC isoform enhances tRNA synthesis and upregulates metabolic gene expression. Together, these findings reveal a previously unrecognised role for Sxl in regulating Pol III activity via Polr3E, promoting tRNA synthesis and supporting neuronal metabolism. Given the emerging tie between Pol III regulation and neuronal ageing, our study highlights Sxl as a novel modulator of neuronal homeostasis.
Project description:The RNA-binding protein sex-lethal (Sxl) is classically defined as a master regulator of sex determination and RNA splicing in Drosophila melanogaster. However, this role is not conserved in all species and functions beyond this canonical pathway remain largely unexplored. Here, we uncover a splicing-independent function for Sxl at the chromatin level in the Drosophila brain. Using Targeted DamID (TaDa) profiling in larval neurons, we identify widespread recruitment of Sxl to promoter regions, independent of sex and RNA binding activity. Notably, Sxl chromatin occupancy exhibits near-complete overlap with Polr3E (RPC37), an RNA Polymerase III subunit, with Sxl binding abolished upon Polr3E knockdown. Depletion of Sxl in mature male neurons equally induces widespread transcriptional changes, particularly in metabolic genes, and improves negative geotaxis during ageing, phenotypes that closely mirror Polr3E knockdown. Conversely, overexpression of SxlRAC isoform enhances tRNA synthesis and upregulates metabolic gene expression. Together, these findings reveal a previously unrecognised role for Sxl in regulating Pol III activity via Polr3E, promoting tRNA synthesis and supporting neuronal metabolism. Given the emerging tie between Pol III regulation and neuronal ageing, our study highlights Sxl as a novel modulator of neuronal homeostasis.
Project description:Sex-lethal is recruited to chromatin to promote neuronal tRNA synthesis in males through RNA Polymerase III regulation [small RNA-seq]
Project description:To adapt RNA polymerase DamID (RAPID) for FLP-mediated spatial control in Caenorhabditis elegans, we inserted a Dam::rpb-6 fusion gene downstream of a FRT-flanked mCh::his-58 cassette and under control of the hsp-16.41 promoter. We introduced a single copy of this construct into the C. elegans genome and crossed the resulting line with a dpy-7p::FLP driver to enable basal Dam::rpb-6 expression in the hypodermis. Nematodes were cultured at 20 degrees Celcius to ensure low levels of Dam::RPB-6 expression in the hypodermis and total genomic DNA was purified from L4 larvae. DNA from animals expressing GFP::Dam was used to control for unspecific methylation. The genome-wide association profile of Dam::RPB-6 was determined by deep sequencing, which revealed a list of 2331 protein coding genes with FDR < 0.05. Original RAPID reference: Gomez-Saldivar et al (2020) Tissue-Specific Transcription Footprinting Using RNA PoI DamID (RAPID) in Caenorhabditis elegans. Genetics 216, 931–945. doi:10.1534/genetics.120.303774
Project description:Many regulatory proteins and complexes have been identified which influence transcription by RNA polymerase (pol) II with a fine precision. In comparison, only a few regulatory proteins are known for pol III, which transcribes mostly house-keeping and non-coding RNAs. Yet, pol III transcription is precisely regulated under various stress conditions like starvation. We used proteomic approaches and pol III transcription complex components TFIIIC (Tfc6), pol III (Rpc128) and TFIIIB (Brf1) as baits to find identify the potential interactors through mass spectrometry-based proteomics. A large number of proteins were found in the interactome, which includes known chromatin modifiers, factors and regulators of transcription by pol I and pol II.