Project description:mRNAs associated with microtubules during interphase, metaphase and the midbody stage of cytokinesis were sequenced. Selective midbody-localized RNAs were identified and their translational characteristics were studied.
Project description:Initiation of bacterial DNA replication takes place at the origin of replication (oriC), a region characterized by the presence of multiple DnaA boxes that serve as the binding sites for the master initiator protein DnaA. The absence or failure of DNA replication can result in bacterial cell growth arrest or death. Here, we aimed to uncover the physiological and molecular consequences of stopping replication in the model bacterium Bacillus subtilis. For this purpose, DNA replication was blocked using a CRISPRi approach specifically targeting DnaA boxes 6 and 7, which are essential for replication initiation. We characterized the phenotype of these cells and analyzed the overall changes in the proteome using quantitative mass spectrometry. Cells with arrested replication were elongating and not dividing but showed no evidence of DNA damage response (DDR). Moreover, these cells did not cease translation over time. This study sets the ground for future research on non-replicating but translationally active B. subtilis, which might be valuable for biotechnological applications.
Project description:The regulation of translation is crucial for cells to rapidly adapt to changing conditions. Although the transcriptional changes under inflammatory conditions are intensely studied, not much is known about translational changes. Therefore, this study aimed at identifying translationally deregulated targets in inflammatory settings.
Project description:The compartmentalisation of distinct organelles within eukaryotic cells is essential for their diverse functions, however, how their structures and functions depend on each other has not been systematically explored. We combined a fluorescent reporter of mitochondrial stress with genome-wide CRISPR knockout screening and identified networks of genes involved in the biogenesis and metabolism of diverse organelles. Targeted organelle gene knockouts identified that defects in peroxisomes, Golgi, and ER cause mitochondrial fragmentation and dysfunction. Correlative light and electron microscopy analysed using artificial intelligence-directed voxel extraction revealed in unprecedented detail how impaired mitochondrial interactions with diverse organelles caused cell-wide defects in their morphology and biogenesis. Multi-omics analyses identified a unified proteome stress response and global shifts in lipid and glycoprotein homeostasis that are elicited when organelle biogenesis is compromised. Our comprehensive resource has defined metabolic and morphological interactions between organelles that can be mined to understand how changes in organelle components drive diverse cellular pathologies.
Project description:Eukaryotic cells contain several membrane-separated organelles to compartmentalize distinct metabolic reactions. However, it has remained unclear how these organelle systems are coordinated, when cells adapt metabolic pathways to support their development, survival or effector functions. Here we present OrgaPlexing, a multispectral organelle imaging approach for the comprehensive mapping of six key metabolic organelles and their interactions. We use this analysis on macrophages, immune cells that undergo rapid metabolic switches upon sensing bacterial and inflammatory stimuli. Our results identify lipid droplets (LDs) as primary inflammatory responder organelle, which forms three- and four-way interactions with other organelles. While clusters with endoplasmic reticulum (ER) and mitochondria (M-ER-LD unit) help supply fatty acids for LD growth, the additional recruitment of peroxisomes (M-ER-P-LD unit) supports fatty acid efflux from LDs. Interference with individual components of these units has direct functional consequences for inflammatory lipid synthesis. Together, we show that macrophages form functional multi-organellar units (MOUs) to support metabolic adaptation, and provide an experimental strategy to identify organelle-metabolic signaling hubs.
Project description:The regulation of translation is crucial for cells to rapidly adapt to changing conditions. Although the transcriptional changes under inflammatory conditions are intensely studied, not much is known about translational changes. Therefore, this study aimed at identifying translationally deregulated targets in inflammatory settings. MCF-7 cells were treated for 4h with the supernatants of U937 monocytes or TPA-activated U937 monocyte-derived macrophages and subjected to polysomal fractionation using sucrose gradients. Total RNA was collected simultaneously.