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: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:The expanded hexanucleotide GGGGCC repeat mutation in the C9orf72 gene is the main genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Under one disease mechanism, sense and antisense transcripts of the repeat are predicted to bind various RNA-binding proteins, compromise their function and cause cytotoxicity. Focusing on cytoplasmic interaction of the CCCCGG antisense repeat RNA this study identifies phenylalanine-tRNA synthetase (FARS) subunit alpha (FARSA) as the main interactor. The aminoacylation of tRNAPhe by FARS is inhibited by antisense RNA, leading to decreased levels of charged tRNAPhe. Remarkably, this is associated with global reduction of phenylalanine incorporation in the proteome and significant decrease in expression of phenylalanine-rich proteins in cellular models and patient tissues. In conclusion, this research reveals functional inhibition of FARSA in the presence of antisense RNA repeats. Compromised aminoacylation of tRNA could lead to impairments in protein synthesis and further contribute to C9orf72 mutation-associated pathology.
Project description:The cytokine interleukin-33 (IL-33) is an epithelial alarmin with critical roles in allergic inflammation and type 2 immunity. The project aims at the characterization of the direct cleavage of IL-33 by allergen proteases, resulting in its activation, and in the subsequent induction of type 2 cytokine production in group 2 innate lymphoid cells. The present dataset contains mass spectrometry analyses to map the cleavage sites for 9 distinct allergens proteases in the human IL-33 sequence.
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:Recombinant expression of proteins, propelled by therapeutic antibodies, has evolved into a multi-billion-dollar industry. Essential here is quality control assessment of critical attributes such as sequence fidelity, proper folding, and post-translational modifications (PTMs). Errors can lead to diminished bioactivity and, in the context of therapeutic proteins, an elevated risk for immunogenicity. Over the years, many techniques were developed and applied to validate proteins in a standardized and high-throughput fashion. One parameter has, however, so far been challenging to assess. Disulfide bridges, covalent bonds linking two Cysteine residues, assist in the correct folding and stability of proteins and thus have a major influence on their efficacy. Mass spectrometry promises to be an optimal technique to uncover them in a fast and accurate fashion. In this work, we present a unique combination of sample preparation, data acquisition and analysis facilitating the rapid and accurate assessment of disulfide bridges in purified proteins. Through microwave-assisted acid hydrolysis (MAAH), the proteins are digested rapidly and artifact-free into peptides, with a substantial degree of overlap over the sequence. The nonspecific nature of this procedure, however, introduces chemical background which is efficiently removed by integrating ion mobility preceding the mass spectrometric measurement. The nonspecific nature of the digestion step additionally necessitates new developments in data analysis, for which we extended the XlinkX node in Proteome Discoverer (XlinkX/PD) to efficiently process the data and ensure correctness through effective false discovery rate correction. The entire workflow can be completed within one hour, allowing for high-throughput, high-accuracy disulfide mapping
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.