Project description:Gene regulatory mechanisms that underlie tissue regeneration have been largely studied at the level of transcription. Here, proximity labeling methods identified enhanced presence of Processing body (P-body) marker, Ddx61, in zebrafish heart muscle cells induced to divide by injury or mitogenic stimulation. We found that Ddx61-containing condensates emerge and develop complex, transient structures in cardiomyocytes during cardiogenic settings in adult zebrafish, developing mice, and human stem cell-derived myocardium. Mutations in zebrafish ddx61 disrupted cardiomyocyte cycling and differentiation after cardiac injury or mitogen presence, and DDX61 knockdown in human cardiomyocytes inhibited similar parameters under maturation conditions in vitro. RNA affinity and proteomic profiling implicated mRNAs preferentially associating with Ddx61 during regeneration, and induced transgenic expression of one of these mRNAs, encoding the BMP signaling inhibitor, Chordin, disrupted indicators of heart regeneration after cardiac injury. Our experiments provide evidence that mRNA sorting by specialized context-dependent condensates can modulate gene expression and impact tissue regenerative capacity.
Project description:Here, we apply differential transcriptome analysis on microscopically isolated cell populations, to define five transcriptional programs that represent each transient embryonic zone and the progression between these zones. The five transcriptional programs contain largely uncharacterized genes in addition to transcripts necessary for stem cell maintenance, neurogenesis, migration, and differentiation. Additionally, we found intergenic transcriptionally active regions that possibly encode novel zone-specific transcripts. Finally, we present a high-resolution transcriptome map of transient zones in the embryonic mouse forebrain. mRNAseq performed after laser microdissection of cells from transient embryonic zones in the mouse cortex
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.
Project description:Here, we apply differential transcriptome analysis on microscopically isolated cell populations, to define five transcriptional programs that represent each transient embryonic zone and the progression between these zones. The five transcriptional programs contain largely uncharacterized genes in addition to transcripts necessary for stem cell maintenance, neurogenesis, migration, and differentiation. Additionally, we found intergenic transcriptionally active regions that possibly encode novel zone-specific transcripts. Finally, we present a high-resolution transcriptome map of transient zones in the embryonic mouse forebrain.
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.
Project description:Nine cigarette smoke condensates (CSCs) were produced under a standard ISO smoking machine regimen and one was produced by a more intense smoking machine regimen. These CSCs were used to treat primary normal human bronchial epithelial cells for 18 hours. Experiment Overall Design: Primary human bronchial/tracheal epithelial cells were grown in culture and treated with 10 different sources of cigarette smoke condensates.
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.
Project description:Like tobacco smoking, habitual marijuana smoking causes numerous adverse pulmonary effects. However, the mechanisms of action involved, especially as compared to tobacco smoke, are still unclear. To uncover putative modes of action, this study employed a toxicogenomics approach to compare the toxicological pathways perturbed following exposure to marijuana and tobacco smoke condensate in vitro. Condensates of mainstream smoke from hand-rolled tobacco and marijuana cigarettes were similarly prepared using identical smoking conditions. Murine lung epithelial cells were exposed to low, medium and high concentrations of the smoke condensates for 6 hr. RNA was extracted immediately or after a 4-hr recovery period and hybridized to mouse whole genome microarrays. Tobacco smoke condensate (TSC) exposure was associated with changes in xenobiotic metabolism, oxidative stress, inflammation, and DNA damage response. These same pathways were also significantly affected following marijuana smoke condensate (MSC) exposure. Although the effects of the condensates were largely similar, dose-response analysis indicates that the MSC is substantially more potent than TSC. In addition, steroid biosynthesis, apoptosis, and inflammation pathways were more significantly affected following MSC exposure, whereas m-phase cell cycle pathways were more significantly affected following TSC exposure. MSC exposure also appeared to elicit more severe oxidative stress than TSC exposure, which may account for the greater cytotoxicity of MSC. This study shows that in general, MSC impacts many of the same molecular processes as TSC. However, subtle pathway differences can provide insight into the differential toxicities of the two complex mixtures. Murine epithelial lung cells were exposed to tobacco smoke condensates (0, 25, 50, 90 μg/ml) or marijuana smoke condensates (0, 2.5, 5, 10 μg/ml) in serum-free medium for a six hour period. Following the six-hour exposure, cells were either harvested immediately or washed with phosphate-buffered saline and incubated in fresh serum-free medium for a four hour recovery period. Total RNA was extracted from the cells and hybridized against Universal Mouse Reference RNA (Agilent Technologies Canada, Inc.) to Agilent whole mouse genome microarray slides containing 44,000 transcripts. A LOWESS normalization was applied to expression results, and statistically significant genes were identified using the R library MAANOVA. Microarray results were validated by real time RT-PCR.
Project description:The gene expression programs that define each cell’s identity are controlled by master transcription factors (TFs) that bind cell-type specific enhancers, as well as signaling factors, which bring extracellular stimuli to these enhancers. Recent studies have revealed that master TFs form phase-separated condensates with the Mediator coactivator at super-enhancers. Here we present evidence that signaling factors for the WNT, TGF-β and JAK/STAT pathways employ their intrinsically disordered regions (IDRs) to enter and concentrate in Mediator condensates at super-enhancers. We show that the WNT coactivator β-catenin interacts both with components of condensates and DNA binding factors to selectively occupy super-enhancer associated genes. We propose that the cell-type specificity of the response to signaling is mediated, in part, by the IDRs of the signaling factors, which cause these factors to partition into condensates established by the master TFs and Mediator at genes with prominent roles in cell identity.