Light induced targeting enables proteomics on endogenous condensates
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PROVIDER: PRJNA1128148 | ENA |
REPOSITORIES: ENA
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Project description:Endogenous condensates with transient constituents are notoriously difficult to study with common biological assays like mass-spectrometry and other proteomics profiling. Here we report a method for light-induced targeting of endogenous condensates (LiTEC) in living cells. LiTEC combines the identification of molecular zip codes that target the endogenous condensates with optogenetics to enable controlled and reversible partitioning of an arbitrary cargo, such as enzymes commonly used in proteomics, into the condensate in a blue light dependent manner. We demonstrate a proof of concept by combining LiTEC with proximity-based biotinylation (BioID) and uncover putative components of transcriptional condensates in mouse embryonic stem cells. Our approach opens the road to genome-wide functional studies of endogenous condensates.
2024-10-18 | GSE270770 | GEO
Project description:Endogenous condensates with transient constituents are notoriously difficult to study with common biological assays like mass-spectrometry and other proteomics profiling. Here we report a method for light-induced targeting of endogenous condensates (LiTEC) in living cells. LiTEC combines the identification of molecular zip codes that target the endogenous condensates with optogenetics to enable controlled and reversible partitioning of an arbitrary cargo, such as enzymes commonly used in proteomics, into the condensate in a blue light dependent manner. We demonstrate a proof of concept by combining LiTEC with proximity-based biotinylation (BioID) and uncover putative components of transcriptional condensates in mouse embryonic stem cells. Our approach opens the road to genome-wide functional studies of endogenous condensates.
2024-10-25 | PXD049054 | Pride
Project description:Hijacking of transcriptional condensates by endogenous retroviruses
| PRJNA669013 | ENA
Project description:Phase separation of biomolecules into condensates is a key mechanism in the spatiotemporal organization of biochemical processes in cells. We systematically engineered light-inducible transcription factor condensates with different material properties and analyzed their influence on transcription activation. When transcription factor condensates were transformed into solid-like gels, we observed a reduced activation of gene expression. We wanted to evaluate the impact that the condensate formation of the transcription factor RelA had on its endogenous promoters using expression data. To this aim, HEK-293T cells were transfected either with empty vector (1-3) or eGFP-RelA (4-6) or eGFP-RelA, Cry2olig-mCh-FUSN-NLS-NbGFP and Cry2olig-mCh-FUSN-NLS, along with an NF-κB-responsive SEAP reporter (7-9). In each of the three groups of transfected cells, 8 h after transfection, 3 samples were kept in the dark (D) and 3 under blue light illumination (BL, 5 μmol m-² s-1) for 24 h prior to RNA extraction. RNA-seq libraries from the 18 samples were sequenced by BGI on a DNBSEQ platform using paired-end chemistry with a read length of 100 base pairs each. Each strand was sequenced across two separate lanes (L03, L04), generating a total of 4 FASTQ files per sample.
2024-04-01 | E-MTAB-13905 | biostudies-arrayexpress
Project description:Heterochromatin plays essential roles in repressing retrotransposons, e.g. endogenous retroviruses (ERVs) during mammalian development, but the contribution of retrotransposition to lethality observed in embryonic cells deficient for heterochromatin-mediated ERV repression is poorly understood. Here we report that selective degradation of the TRIM28 heterochromatin adapter protein leads to reduced association of transcriptional condensates with loci encoding super-enhancer -driven pluripotency genes in embryonic stem cells, a collapse of the pluripotency transcriptional circuit, and a pre-lethal restriction of pluripotent lineages in mouse embryos. De-repressed ERVs recruit transcriptional condensates in the absence of TRIM28, and ERV RNA facilitates condensation of RNA Polymerase II in vitro. We propose that retrotransposons contribute to the genomic distribution of nuclear condensates, and that RNA species may facilitate “hijacking” of transcriptional condensates in various developmental and disease contexts.
2022-07-08 | PXD021895 | Pride
Project description:Phase separation inside mammalian cells regulates the formation of biomolecular condensates that are related to gene expression, signalling, development, and diseases. However, a large population of endogenous condensates and their candidate phase separating proteins have yet to be discovered in a quantitative and high-throughput manner. Here, we demonstrate that endogenously-expressed biomolecular condensates can be identified across a cell's proteome by sorting proteins across varying oligomeric states. We employ volumetric compression to modulate the concentrations of intracellular proteins and the degree of crowdedness, which are physical regulators of cellular biomolecular condensates. The changes in degree of the partition of proteins into condensates or phase separation lead to varying oligomeric states of the proteins, which can be detected by coupling density gradient ultracentrifugation and quantitative mass spectrometry. In total, we identified 1,518 endogenous-expression condensate proteins, of which 538 have not been reported before. Furthermore, we demonstrate that our strategy can identify condensate proteins that respond to specific biological processes.
2024-03-18 | PXD048218 | Pride
Project description:Most endogenous retroviruses (ERVs) in mammals are incapable of retrotransposition; therefore, why ERV de-repression is associated with lethality during early development has been a mystery. Here we report that rapid and selective degradation of the TRIM28 heterochromatin adapter protein triggers dissociation of transcriptional condensates from loci encoding super-enhancer -driven pluripotency genes, and their association with transcribed ERV loci in murine embryonic stem cells. Knockdown of ERV RNAs or forced expression of super-enhancer -enriched transcription factors rescued condensate localization at super-enhancers in TRIM28-degraded cells. In a biochemical reconstitution system, ERV RNA facilitated partitioning of RNA Polymerase II, and the Mediator co- activator into phase-separated droplets. In TRIM28 knockout mouse embryos, single-cell RNA-Seq analysis revealed specific depletion of pluripotent lineages. We propose that coding and non-coding nascent RNAs, including those produced by retrotransposons, may facilitate “hijacking” of transcriptional condensates in various developmental and disease contexts.
2022-03-30 | GSE159468 | GEO
Project description:PHF8 enables immune evasion by silencing endogenous retroelements
| PRJNA877236 | ENA
Project description:PHF8 enables immune evasion by silencing endogenous retroelements.
| PRJNA870723 | ENA
Project description:Compartmentalization is an essential feature of eukaryotic life and is achieved both via membrane-bound organelles, such as mitochondria, and membrane-less biomolecular condensates, such as the nucleolus. Known biomolecular condensates typically exhibit liquid-like properties and are visualized by microscopy on the scale of ~1µm. They have been studied mostly by microscopy, examining select individual proteins. So far, several dozen biomolecular condensates are known, serving a multitude of functions, for example, in the regulation of transcription, RNA processing or signalling and their malfunction can cause diseases. However, it remains unclear to what extent biomolecular condensates are utilized in cellular organization and at what length scale they typically form. Here we examine native cytoplasm from Xenopus egg extract on a global scale with quantitative proteomics, filtration, size exclusion and dilution experiments. These assays reveal that at least 18% of the proteome is organized into mesoscale biomolecular condensates at the scale of ~100nm and appear to be stabilized by RNA or gelation. We confirmed mesoscale sizes via imaging below the diffraction limit by investigating protein permeation into porous substrates with defined pore sizes. Our results show that eukaryotic cytoplasm organizes extensively via biomolecular condensates, but at surprisingly short length scales.
2023-11-02 | GSE232651 | GEO