Project description:We have knocked out a putative N-acetyl transferase, Pf3D7_1437000, from the malaria parasite plasmodium falciparum. Pf3D7_1437000 resides in the ER. Proteins in the Plasmodium falciparum secretory pathway are known to be extensively N-terminally acetylated. We have isolated two such proteins, HRP2 and HRP3, from the WT and KO parasites compared there N terminal acetylation status.
Project description:In vitro studies identified various factors including P-TEFb, SEC, SPT6, PAF1, DSIF, and NELF functioning at different stages of transcription elongation driven by RNA polymerase II (RNA Pol II). What remains unclear is how these factors cooperatively regulate pause/release and productive elongation in the context of living cells. Using an acute 5 protein-depletion approach, prominent release and a subsequent increase in mature transcripts, whereas long genes fail to yield mature transcripts due to a loss of processivity. Mechanistically, loss of SPT6 results in loss of PAF1 complex (PAF1C) from RNA Pol II, leading to NELF-bound RNA Pol II release into the gene bodies. Furthermore, SPT6 and/or PAF1 depletion impairs heat shock-induced pausing, pointing to a role for SPT6 in regulating RNA Pol II pause/release through the recruitment of PAF1C during the early elongation.
Project description:Alzheimer’s disease is associated with disrupted circadian rhythms and clock gene expression. REV-ERBα (Nr1d1) is a circadian transcriptional repressor involved in the regulation of lipid metabolism and macrophage function. While global REV-ERBα deletion increases microglial activation and mitigates amyloid plaque formation, the cell-autonomous effects of microglial REV-ERBα deletion in healthy brain and in tauopathy are unexplored. Here, we show that microglial REV-ERBα deficient enhances inflammatory signaling, disrupts lipid metabolism, and causes lipid droplet (LD) accumulation specifically in male microglia. Inflammation and LD accumulation combine to inhibit microglial tau phagocytosis, which can be partially rescued by blockage of lipid droplet formation. Microglial REV-ERBα deletion exacerbates tau aggregation and neuroinflammation in P301S and AAV-P301L tauopathy models in male, but not female mice. These data demonstrate the importance of microglial lipid droplets in tau accumulation and reveal REV-ERBα as a therapeutically accessible, sex-dependent regulator of microglial inflammatory signaling, lipid metabolism, and tauopathy.
Project description:Dietary unsaturated fatty acids beneficially affect human health, in part by modulating the immune system, but the mechanism is not completely understood. Given that unsaturated fatty acids have been shown to be covalently incorporated into a small subset of proteins, we designed three alkyne-tagged chemical reporters of unsaturated fatty acids, alk-16:1, alk-17:1 and alk-18:1, to explore the generality and diversity of this protein modification. Following cell lysis, proteins labelled with the reporters could be captured by azido-functionalized reagents via CuAAC for fluorescence detection or enrichment for proteomics analysis. These reporters label many proteins in mammalian cells and can be incorporated site-specifically, notably on Cys residues. Quantitative proteomics analysis (n= 4 biological replicates) of LPS/IFN-gamma stimulated RAW264.7 labelled with oleic acid (control), alk-16 (palmitic acid chemical reporter), alk-16:1, alk-17:1 and alk-18:1, revealed that unsaturated fatty acids modify similar protein targets to saturated fatty acids, including several immune proteins. Interestingly, some proteins can be differentially labeled with unsaturated and saturated fatty acid.
Project description:We provide evidence that a member of the human Schlafen (SLFN) family of proteins, SLFN5, is overexpressed in human pancreatic ductal adenocarcinoma (PDAC). Targeted deletion of SLFN5 results in decreased PDAC cell proliferation and suppresses PDAC tumorigenesis in in vivo PDAC models. Importantly, high expression levels of SLFN5 correlate with worse outcomes in PDAC patients, implicating SLFN5 in the pathophysiology of PDAC that leads to poor outcomes. Our studies establish novel regulatory effects of SLFN5 on cell cycle progression through binding/blocking of the transcriptional repressor E2F7, promoting transcription of key genes that stimulate S phase progression. Together, our studies suggest an essential role for SLFN5 in PDAC and support the potential for developing new therapeutic approaches for the treatment of pancreatic cancer through SLFN5 targeting.
Project description:A proteome-wide analysis was performed in Escherichia coli to identify the impact on protein N-termini of the antibiotic actinonin specifically inhibiting peptide deformylase (PDF). A new strategy and tool suite (SILProNaQ) was employed to provide large scale N-terminus acetylation yield quantitation. In control conditions, more than 1000 N-termini could be identified with 56 % Met removal, and additional modifications involving partial or complete N-acetylation (10%) and formyl retention (5%). Among the proteins undergoing these N-terminal modifications, some translocated membrane proteins were highlighted. The early time-course impact of actinonin was followed after the addition of bacteriostatic concentrations of the drug immediately slowing down the growth rate. Under these conditions, 25% of all proteins remain formylated after 10 min, a value reaching more than 60% of all characterized proteins after 40 min of treatment. The N-formylation rate on individual proteins increased with the same trend. Upon PDF inhibition, we finally show that two major categories of proteins retain their formyl group: a large number of inner membrane proteins and proteins involved in protein synthesis including many factors assisting the nascent chains in co-translational events.
Project description:The microtubule network is formed from polymerised tubulin subunits and associating proteins, which govern microtubule dynamics and a diverse array of functions. To identify novel microtubule binding proteins, we have developed an unbiased biochemical assay which relies on the selective extraction of cytosolic proteins from cells, whilst leaving behind the microtubule network. Candidate proteins are linked to microtubules by their sensitivities to the depolymerising drug nocodazole or the microtubule stabilising drug, taxol, which are then quantitated in a triplex experiment. Our approach is first benchmarked by co-segregation of tubulin and previously established microtubule-binding proteins. We then identify several novel candidate microtubule binding proteins. Amongst these, we have selected the ubiquitin E3 ligase TRIM3 (Tripartite motif-containing protein 3) for further characterisation. TRIM3 binding to microtubules is mapped to its C-terminal NHL-repeat region. We show that TRIM3 is required for the rapid accumulation of acetylated tubulin, following treatment with the microtubule stabilising drug taxol. Furthermore, loss of TRIM3, partially recapitulates the reduction in nocodozole resistant microtubules characteristic of Alpha Tubulin Acetyltransferase 1 (ATAT1) depletion. These results can be explained by a decrease in ATAT1 that follows depletion of TRIM3 that is independent of transcription.
Project description:Extracellular vesicles (EV) as drug delivery nanocarriers are under intense investigation. Although clinical-grade EVs have been produced on a large-scale, low yield and high production costs of natural EVs (nEV) limit the relevant industrial translation. Recent studies show that mechanical extrusion of cells can generate nEV-like engineered EVs (eEV) which can also be used as drug nanocarriers. Moreover, in comparison with nEVs, eEVs have similar physicochemical properties. Nevertheless, a comprehensive comparison of cargo between nEVs and eEVs has not been investigated yet. Therefore, the aim of this study is to profile and compare eEVs to nEVs. Our results show that no significant difference was found in size, morphology, and classical markers between nEVs and eEVs derived from MDA-MB-231 cells. Protein sequencing data reveals the similarity of membrane proteins between the two groups was ~71%, while it was ~21% when pertaining to total protein cargo. Notably, a high similarity of membrane proteins was also found between nEVs and eEVs derived from eight additional cancer cell lines. Moreover, analysis of the top 1000 small RNA with RNA sequencing showed a ~65% similarity between the two groups. Altogether, we infer from the high similarity of membrane proteins and small RNA cargo that eEVs can be a good substitute for nEVs. In brief, our findings support previous studies which discovered eEVs own comparable performance of nEVs and could pave the way for clinical implementation of eEV-based therapeutics in the future.
Project description:This project aims to understand better the stress response mechanisms of components of the well known High Osmolarity Glycerol two-component regulatory system in the model organism Magnaporthe oryzae. Currently, two putative isoforms of the transfer protein YPD1 (MGG_07173) are described as theoretical proteins in the UniProt database (G4MTL0 and G4MTK9). For better understanding of signal transduction and response triggering we aimed to identify alternative isoforms that might explain the variety of triggered responses throughout the YPD1 signal transfer hub.