| 1. |
- Bednarska, Natalia G., et al.
(author)
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Protein aggregation as an antibiotic design strategy
- 2016
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In: Molecular Microbiology. - : WILEY-BLACKWELL. - 0950-382X .- 1365-2958. ; 99:5, s. 849-865
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Journal article (peer-reviewed)abstract
- Taking advantage of the xenobiotic nature of bacterial infections, we tested whether the cytotoxicity of protein aggregation can be targeted to bacterial pathogens without affecting their mammalian hosts. In particular, we examined if peptides encoding aggregation-prone sequence segments of bacterial proteins can display antimicrobial activity by initiating toxic protein aggregation in bacteria, but not in mammalian cells. Unbiased in vitro screening of aggregating peptide sequences from bacterial genomes lead to the identification of several peptides that are strongly bactericidal against methicillin-resistant Staphylococcus aureus. Upon parenteral administration in vivo, the peptides cured mice from bacterial sepsis without apparent toxic side effects as judged from histological and hematological evaluation. We found that the peptides enter and accumulate in the bacterial cytosol where they cause aggregation of bacterial polypeptides. Although the precise chain of events that leads to cell death remains to be elucidated, the ability to tap into aggregation-prone sequences of bacterial proteomes to elicit antimicrobial activity represents a rich and unexplored chemical space to be mined in search of novel therapeutic strategies to fight infectious diseases.
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| 2. |
- Bogaert, Annelies, et al.
(author)
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N-terminal proteoforms may engage in different protein complexes
- 2023
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In: Life Science Alliance. - : Life Science Alliance, LLC. - 2575-1077. ; 6:8
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Journal article (peer-reviewed)abstract
- Alternative translation initiation and alternative splicing may give rise to N-terminal proteoforms, proteins that differ at their N-terminus compared with their canonical counterparts. Such proteoforms can have altered localizations, stabilities, and functions. Although proteoforms generated from splice variants can be engaged in different protein complexes, it remained to be studied to what extent this applies to N-terminal proteoforms. To address this, we mapped the interactomes of several pairs of N-terminal proteoforms and their canonical counterparts. First, we generated a catalogue of N-terminal proteoforms found in the HEK293T cellular cytosol from which 22 pairs were selected for interactome profiling. In addition, we provide evidence for the expression of several N-terminal proteoforms, identified in our catalogue, across different human tissues, as well as tissue-specific expression, highlighting their biological relevance. Protein–protein interaction profiling revealed that the overlap of the interactomes for both proteoforms is generally high, showing their functional relation. We also showed that N-terminal proteoforms can be engaged in new interactions and/or lose several interactions compared with their canonical counterparts, thus further expanding the functional diversity of proteomes.
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| 3. |
- Dooley, James, et al.
(author)
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Genetic predisposition for beta cell fragility underlies type 1 and type 2 diabetes
- 2016
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 48, s. 519-527
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Journal article (peer-reviewed)abstract
- Type 1 (T1D) and type 2 (T2D) diabetes share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, whereas beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in Xrcc4 and Glis3 alters the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role of beta cell fragility in genetic predisposition to diabetes.
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| 4. |
- Escamez, Sacha, 1987-, et al.
(author)
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Extracellular peptide Kratos restricts cell death during vascular development and stress in Arabidopsis
- 2019
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In: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 70:7, s. 2199-2210
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Journal article (peer-reviewed)abstract
- During plant vascular development, xylem tracheary elements (TEs) form water-conducting, empty pipes by genetically regulated cell death. Cell death is prevented from spreading to non-TEs by unidentified intercellular mechanisms, downstream of METACASPASE9 (MC9)-mediated regulation of autophagy in TEs. Here, we identified differentially abundant extracellular peptides in vascular-differentiating wild-type and MC9-down-regulated Arabidopsis cell suspensions. A peptide named Kratos rescued the abnormally high ectopic non-TE death resulting from either MC9 knockout or TE-specific overexpression of the ATG5 autophagy protein during experimentally induced vascular differentiation in Arabidopsis cotyledons. Kratos also reduced cell death following mechanical damage and extracellular ROS production in Arabidopsis leaves. Stress-induced but not vascular non-TE cell death was enhanced by another identified peptide, named Bia. Bia is therefore reminiscent of several known plant cell death-inducing peptides acting as damage-associated molecular patterns. In contrast, Kratos plays a novel extracellular cell survival role in the context of development and during stress response.
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| 5. |
- Gallardo, Rodrigo, et al.
(author)
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De novo design of a biologically active amyloid
- 2016
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In: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 354:6313, s. 720-
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Journal article (peer-reviewed)abstract
- Most human proteins possess amyloidogenic segments, but only about 30 are associated with amyloid-associated pathologies, and it remains unclear what determines amyloid toxicity. We designed vascin, a synthetic amyloid peptide, based on an amyloidogenic fragment of vascular endothelial growth factor receptor 2 (VEGFR2), a protein that is not associated to amyloidosis. Vascin recapitulates key biophysical and biochemical characteristics of natural amyloids, penetrates cells, and seeds the aggregation of VEGFR2 through direct interaction. We found that amyloid toxicity is observed only in cells that both express VEGFR2 and are dependent on VEGFR2 activity for survival. Thus, amyloid toxicity here appears to be both protein-specific and conditional-determined by VEGFR2 loss of function in a biological context in which target protein function is essential.
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| 6. |
- Lâm, Xuân Tâm, 1986-, et al.
(author)
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Proteomic approaches to identify substrates of the three Deg/HtrA proteases of the cyanobacterium Synechocystis sp. PCC 6803
- 2015
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In: Biochemical Journal. - : Portland Press. - 0264-6021 .- 1470-8728. ; 468:3, s. 373-384
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Journal article (peer-reviewed)abstract
- The family of Deg/HtrA proteases plays an important role in quality control of cellular proteins in a wide range of organisms. In the genome of the cyanobacterium Synechocystis sp. PCC 6803, a model organism for photosynthetic research and renewable energy products, three Deg proteases are encoded, termed HhoA, HhoB and HtrA. In the present study, we compared wild-type (WT) Synechocystis cells with the single insertion mutants ΔhhoA, ΔhhoB and ΔhtrA. Protein expression of the remaining Deg/HtrA proteases was strongly affected in the single insertion mutants. Detailed proteomic studies using DIGE (difference gel electrophoresis) and N-terminal COFRADIC (N-terminal combined fractional diagonal chromatography) revealed that inactivation of a single Deg protease has similar impact on the proteomes of the three mutants; differences to WT were observed in enzymes involved in the major metabolic pathways. Changes in the amount of phosphate permease system Pst-1 were observed only in the insertion mutant ΔhhoB. N-terminal COFRADIC analyses on cell lysates of ΔhhoB confirmed changed amounts of many cell envelope proteins, including the phosphate permease systems, compared with WT. In vitro COFRADIC studies were performed to identify the specificity profiles of the recombinant proteases rHhoA, rHhoB or rHtrA added to the Synechocystis WT proteome. The combined in vivo and in vitro N-terminal COFRADIC datasets propose RbcS as a natural substrate for HhoA, PsbO for HhoB and HtrA and Pbp8 for HtrA. We therefore suggest that each Synechocystis Deg protease protects the cell through different, but connected mechanisms.
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| 7. |
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| 8. |
- Mestdagh, Pieter, et al.
(author)
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The miR-17-92 MicroRNA Cluster Regulates Multiple Components of the TGF-beta Pathway in Neuroblastoma
- 2010
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In: Molecular Cell. - : Elsevier BV. - 1097-4164 .- 1097-2765. ; 40:5, s. 762-773
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Journal article (peer-reviewed)abstract
- The miR-17-92 microRNA cluster is often activated in cancer cells, but the identity of its targets remains elusive. Using SILAC and quantitative mass spectrometry, we examined the effects of activation of the miR-17-92 cluster on global protein expression in neuroblastoma (NB) cells. Our results reveal cooperation between individual miR-17-92 miRNAs and implicate miR-17-92 in multiple hallmarks of cancer, including proliferation and cell adhesion. Most importantly, we show that miR-17-92 is a potent inhibitor of TGF-beta signaling. By functioning both upstream and downstream of pSMAD2, miR-17-92 activation triggers downregulation of multiple key effectors along the TGF-beta signaling cascade as well as direct inhibition of TGF-beta-responsive genes.
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| 9. |
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| 10. |
- Stael, Simon, et al.
(author)
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Structure-function study of a Ca2+-independent metacaspase involved in lateral root emergence
- 2023
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences (PNAS). - 0027-8424 .- 1091-6490. ; 120
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Journal article (peer-reviewed)abstract
- Metacaspases are part of an evolutionarily broad family of multifunctional cysteine proteases, involved in disease and normal development. As the structure-function relationship of metacaspases remains poorly understood, we solved the X-ray crystal structure of an Arabidopsis thaliana type II metacaspase (AtMCA-IIf) belonging to a particular subgroup not requiring calcium ions for activation. To study metacaspase activity in plants, we developed an in vitro chemical screen to identify small molecule metacaspase inhibitors and found several hits with a minimal thioxodihydropyrimidine-dione structure, of which some are specific AtMCA-IIf inhibitors. We provide mechanistic insight into the basis of inhibition by the TDP-containing compounds through molecular docking onto the AtMCA-IIf crystal structure. Finally, a TDP-containing compound (TDP6) effectively hampered lateral root emergence in vivo, probably through inhibition of metacaspases specifically expressed in the endodermal cells overlying developing lateral root primordia. In the future, the small compound inhibitors and crystal structure of AtMCA-IIf can be used to study metacaspases in other species, such as important human pathogens, including those causing neglected diseases.
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