Project description:Cardiac fibrosis occurs following insults to the myocardium and is characterized by the abnormal accumulation of non-compliant extracellular matrix (ECM), which compromises cardiomyocyte (CMs) contractile activity and eventually leads to heart failure. This phenomenon is driven by the differentiation of cardiac fibroblasts (cFbs) into myofibroblasts and results in changes in ECM biochemical and structural properties. The lack of predictive in vitro models of heart fibrosis has so far hampered the search for innovative treatments. Here, we adopted a protocol to generate cFbs from human induced pluripotent stem cells (iPSCs) and activate them to a myofibroblast phenotype by tuning basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-β) signalling. We next confirmed that TGF-β stimulation prompted iPSC-derived cells to acquire key features of myofibroblasts, like SMAD2/3 nuclear shuttling, the formation of aligned alpha-smooth muscle actin (α-SMA)-rich stress fibres and increased focal adhesions (FAs) assembly. Additionally, we devised a single-step decellularization protocol to obtain and thoroughly characterize the biochemical and mechanical properties of the ECM secreted by activated cFbs. After revealing that iPSC-derived myofibroblasts secrete an abundant, collagen-rich and stiff ECM characterized by distinct viscoelastic properties, we demonstrated that this pro-fibrotic ECM activates mechanosensitive pathways in iPSC-derived CMs (iPSC-CMs), impacting their shape, sarcomere length, phenotype and calcium handling properties. We thus propose these human bio-inspired matrices as animal-free, isogenic CM culture substrates recapitulating key pathophysiological changes occurring at the cellular level during cardiac fibrosis.
Project description:Prader-Willi syndrome (PWS) is a multisystem disorder caused by loss of expression of a cluster of paternally-expressed, imprinted genes. Neonatal failure to thrive is followed by childhood-onset hyperphagia, obesity, neurobehavioral abnormalities, and hormonal deficits. Prior evidence from a mouse model with a deletion of the orthologous PWS-domain identified abnormal pancreatic islet development with deficient insulin secretion, hypoglucagonemia, and postnatal onset of progressive, lethal hypoglycemia. To investigate PWS-genes in β-cell secretory function, we used CRISPR/Cas9 genome-editing to generate isogenic, clonal INS-1 insulinoma lines with 3.16 Mb deletions of the silent, maternal (control) or active, paternal (PWS) alleles. A significant reduction in basal and glucose-stimulated insulin secretion signifies a cell autonomous insulin secretion deficit in PWS β-cells. Parallel proteome and transcriptome studies revealed reduced levels of secreted peptides and for eleven endoplasmic reticulum (ER) chaperones, including HSPA5 and HSP90B1. In contrast to dosage compensation previously seen for ER chaperones in Hspa5 or Hsp90b1 gene knockouts, compensation is precluded by the widespread deficiency of ER chaperones in PWS cells. Remarkably, but consistent with reduced ER chaperone levels, PWS β-cells are more sensitive to ER stress activation of all three regulatory pathways (XBP1, eIF2α-P, ATF6-N). Therefore, a coordinated, chronic deficit of ER chaperones in PWS β-cells is hypothesized to lead to a delay in ER transit and/or folding of insulin and other cargo along the secretory pathway. These findings provide insight into the pathophysiological basis of hormone deficits in PWS and indicate key roles for PWS-imprinted genes in β-cell secretory function.
Project description:We utilized the well-characterized murine T cell transfer model of colitis to find specific alterations in the intestinal luminal proteome associated with inflammation. Mass spectrometry proteomic analysis of colonic samples permitted the identification of ~10,000-12,000 unique peptides that corresponded to 5610 protein clusters identified across three groups, including the colitic Rag1 -/- T cell recipients, isogenic Rag1 -/- controls, as well as wild-type mice. Bioinformatic analyses on host and microbial proteins found specific proteins and GO term functionalities unique to each group, as well as GO terms shared across the three cohorts. We further demonstrated that the colitic mice exhibited a significant increase in Proteobacteria and Verrucomicrobia that was substantiated with 16S rDNA sequencing.
Project description:Trypanosome histone N-terminal sequences are very divergent from the other eukaryotes, although they are still decorated by post-translational modifications (PTMs). Here, we used a highly robust workflow to analyze histone PTMs in the parasite Trypanosoma cruzi using mass spectrometry-based data-independent acquisition (DIA). We adapted the workflow for the analysis of the parasite’s histone sequences by modifying the software EpiProfile 2.0, improving peptide and PTM quantification accuracy. This workflow could now be applied to the study of 141 T. cruzi modified histone peptides, which we used to investigate the dynamics of histone PTMs along the metacyclogenesis and the life cycle of T. cruzi.
Project description:Drak2¬-deficient (Drak2-/-) mice are resistant to multiple models of autoimmunity, yet effectively eliminate pathogens and tumors. Thus, DRAK2 is an ideal target to treat autoimmune diseases. However, the mechanisms by which DRAK2 contributes to autoimmunity, particularly type 1 diabetes (T1D), remain unresolved. Our data indicate that DRAK2 contributes to autoimmunity in multiple ways by regulating thymic Treg development and by impacting the sensitivity of conventional T cells to Treg-mediated suppression.
Project description:Decellularized extracellular matrix (dECM) is used to make regenerative biomaterials. As the ECM markups vary across organs, derived dECM products may possess different molecular and biological profiles as well. This study aims to compare the proteomic profiles of dECM biomaterials derived from small intestinal submucosa (SIS) and vocal fold (VF) tissue using mass spectrometry-based proteomics.
Project description:A wide range of protein acyl modifications has been identified on enzymes across various metabolic processes; however, the impact of these modifications remains poorly understood. Protein glutarylation is a recently identified modification that can be non-enzymatically driven by glutaryl-CoA. In mammalian systems, this unique metabolite is only produced in the lysine and tryptophan oxidative pathways. To better understand the biology of protein glutarylation, we studied the relationship between enzymes within the lysine/tryptophan catabolic pathways, protein glutarylation, and regulation by the deglutarylating enzyme Sirtuin 5 (SIRT5). Here, we identify glutarylation of the lysine oxidation pathway enzyme glutaryl-CoA dehydrogenase (GCDH). We show increased GCDH glutarylation when glutaryl-CoA production is stimulated by lysine catabolism. Our data reveal glutarylation of GCDH impacts its function, ultimately decreasing lysine oxidation. We then demonstrate the ability of SIRT5 to deglutarylate GCDH, restoring its enzymatic activity. Finally, metabolomic and bioinformatic data indicate a novel role for SIRT5 in regulation of amino acid metabolism. Together, these data suggest a model whereby a feedback loop exists within the lysine/tryptophan oxidation pathway, in which glutaryl-CoA is produced, in turn inhibiting GCDH function. This inhibition is relieved by SIRT5 deacylation activity.
Project description:Recently, we elucidated T. urticae’s repertoire of secreted salivary proteins, revealing several members of expanded protein families with unknown functions [PMID: 27703040]. In this study, mite salivary secretions were additionally examined using a peptidomics approach.
Project description:Candida albicans is an opportunist pathogen responsible for a large spectrum of infections, from superficial mycosis to the systemic disease candidiasis. Its ability to adopt various morphological forms, such as unicellular yeasts, filamentous pseudohyphae and hyphae, contributes to its ability to survive within the host. It has been suggested that the antioxidant glutathione is involved in the filamentation process. We investigated S-glutathionylation, the reversible binding of glutathione to proteins, and the functional consequences on C. albicans metabolic remodeling during the yeast-to-hyphae transition. Our work provided evidence for the specific glutathionylation of mitochondrial proteins involved in bioenergetics pathways in filamentous forms and a regulation of the main enzyme of the glyoxylate cycle, isocitrate lyase, by glutathionylation. Our proteomic data demonstrate that the binding of one glutathione molecule to isocitrate lyase in the hyphal forms leads to enzyme inactivation which was reversed by glutaredoxin treatment. We also assessed the effect of alternative carbon sources on glutathione levels and isocitrate lyase activity. Changes in nutrient availability led to morphological flexibility and was related to perturbations in glutathione levels and isocitrate lyase activity, confirming the key role of the maintenance of intracellular redox status in the adaptive metabolic strategy of the pathogen.
Project description:BACKGROUND: Cervical carcinoma develops as a result of multiple genetic alterations. Different studies investigated genomic alterations in cervical cancer mainly by means of metaphase comparative genomic hybridization (mCGH) and microsatellite marker analysis for the detection of loss of heterozygosity (LOH). Currently, high throughput methods such as array comparative genomic hybridization (array CGH), single nucleotide polymorphism array (SNP array) and gene expression arrays are available to study genome-wide alterations. Integration of these 3 platforms allows detection of genomic alterations at high resolution and investigation of an association between copy number changes and expression. RESULTS: Genome-wide copy number and genotype analysis of 10 cervical cancer cell lines by array CGH and SNP array showed highly complex large-scale alterations. A comparison between array CGH and SNP array revealed that the overall concordance in detection of the same areas with copy number alterations (CNA) was above 90%. The use of SNP arrays demonstrated that about 75% of LOH events would not have been found by methods which screen for copy number changes, such as array CGH, since these were LOH events without CNA. Regions frequently targeted by CNA, as determined by array CGH, such as amplification of 5p and 20q, and loss of 8p were confirmed by fluorescent in situ hybridization (FISH). Genome-wide, we did not find a correlation between copy-number and gene expression. At chromosome arm 5p however, 22% of the genes were significantly upregulated in cell lines with amplifications as compared to cell lines without amplifications, as measured by gene expression arrays. For 3 genes, SKP2, ANKH and TRIO, expression differences were confirmed by quantitative real-time PCR (qRT-PCR). CONCLUSION: This study showed that copy number data retrieved from either array CGH or SNP array are comparable and that the integration of genome-wide LOH, copy number and gene expression is useful for the identification of gene specific targets that could be relevant for the development and progression in cervical cancer. Keywords: DNA copynumber RNA expression correlation Cervival cancer cell lines were hybridized to Affymetrix Focus arrays in duplicate. Correlations were made with copynumber profiles from arrayCGH and SNP arrays.