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| 2. |
- Kohler, Verena, 1992-, et al.
(författare)
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TraN: A novel repressor of an Enterococcus conjugative type IV secretion system
- 2018
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Ingår i: Nucleic Acids Research. - : Oxford University Press. - 0305-1048 .- 1362-4962. ; 46:17, s. 9201-9219
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Tidskriftsartikel (refereegranskat)abstract
- The dissemination of multi-resistant bacteria represents an enormous burden on modern healthcare. Plasmid-borne conjugative transfer is the most prevalent mechanism, requiring a type IV secretion system that enables bacteria to spread beneficial traits, such as resistance to last-line antibiotics, among different genera. Inc18 plasmids, like the Gram-positive broad host-range plasmid pIP501, are substantially involved in propagation of vancomycin resistance from Enterococci to methicillin-resistant strains of Staphylococcus aureus. Here, we identified the small cytosolic protein TraN as a repressor of the pIP501-encoded conjugative transfer system, since deletion of traN resulted in upregulation of transfer factors, leading to highly enhanced conjugative transfer. Furthermore, we report the complex structure of TraN with DNA and define the exact sequence of its binding motif. Targeting this protein–DNA interaction might represent a novel therapeutic approach against the spreading of antibiotic resistances.
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| 3. |
- Zarb, Yvette, et al.
(författare)
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Ossified blood vessels in primary familial brain calcification elicit a neurotoxic astrocyte response
- 2019
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Ingår i: Brain. - : OXFORD UNIV PRESS. - 0006-8950 .- 1460-2156. ; 142:4, s. 885-902
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Tidskriftsartikel (refereegranskat)abstract
- Brain calcifications are commonly detected in aged individuals and accompany numerous brain diseases, but their functional importance is not understood. In cases of primary familial brain calcification, an autosomally inherited neuropsychiatric disorder, the presence of bilateral brain calcifications in the absence of secondary causes of brain calcification is a diagnostic criterion. To date, mutations in five genes including solute carrier 20 member 2 (SLC20A2), xenotropic and polytropic retrovirus receptor 1 (XPR1), myogenesis regulating glycosidase (MYORG), platelet-derived growth factor B (PDGFB) and platelet-derived growth factor receptor beta (PDGFRB), are considered causal. Previously, we have reported that mutations in PDGFB in humans are associated with primary familial brain calcification, and mice hypomorphic for PDGFB (Pdgfb(ret/ret)) present with brain vessel calcifications in the deep regions of the brain that increase with age, mimicking the pathology observed in human mutation carriers. In this study, we characterize the cellular environment surrounding calcifications in Pdgfb(ret/ret) animals and show that cells around vessel-associated calcifications express markers for osteoblasts, osteoclasts and osteocytes, and that bone matrix proteins are present in vessel-associated calcifications. Additionally, we also demonstrate the osteogenic environment around brain calcifications in genetically confirmed primary familial brain calcification cases. We show that calcifications cause oxidative stress in astrocytes and evoke expression of neurotoxic astrocyte markers. Similar to previously reported human primary familial brain calcification cases, we describe high interindividual variation in calcification load in Pdgfb(ret/ret) animals, as assessed by ex vivo and in vivo quantification of calcifications. We also report that serum of Pdgfb(ret/ret) animals does not differ in calcification propensity from control animals and that vessel calcification occurs only in the brains of Pdgfb(ret/ret) animals. Notably, ossification of vessels and astrocytic neurotoxic response is associated with specific behavioural and cognitive alterations, some of which are associated with primary familial brain calcification in a subset of patients.
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| 4. |
- Aufschnaiter, Andreas, et al.
(författare)
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The Coordinated Action of Calcineurin and Cathepsin D Protects Against alpha-Synuclein Toxicity
- 2017
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The degeneration of dopaminergic neurons during Parkinson's disease (PD) is intimately linked to malfunction of alpha-synuclein (alpha Syn), the main component of the proteinaceous intracellular inclusions characteristic for this pathology. The cytotoxicity of alpha Syn has been attributed to disturbances in several biological processes conserved from yeast to humans, including Ca2+ homeostasis, general lysosomal function and autophagy. However, the precise sequence of events that eventually results in cell death remains unclear. Here, we establish a connection between the major lysosomal protease cathepsin D (CatD) and the Ca2+/calmodulin-dependent phosphatase calcineurin. In a yeast model for PD, high levels of human alpha Syn triggered cytosolic acidification and reduced vacuolar hydrolytic capacity, finally leading to cell death. This could be counteracted by overexpression of yeast CatD (Pep4), which re-installed pH homeostasis and vacuolar proteolytic function, decreased alpha Syn oligomers and aggregates, and provided cytoprotection. Interestingly, these beneficial effects of Pep4 were independent of autophagy. Instead, they required functional calcineurin signaling, since deletion of calcineurin strongly reduced both the proteolytic activity of endogenous Pep4 and the cytoprotective capacity of overexpressed Pep4. Calcineurin contributed to proper endosomal targeting of Pep4 to the vacuole and the recycling of the Pep4 sorting receptor Pep1 from prevacuolar compartments back to the trans-Golgi network. Altogether, we demonstrate that stimulation of this novel calcineurin-Pep4 axis reduces alpha Syn cytotoxicity.
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| 5. |
- Ellinghaus, David, et al.
(författare)
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Association between variants of PRDM1 and NDP52 and Crohn's disease, based on exome sequencing and functional studies
- 2013
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Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085 .- 1528-0012. ; 145:2, s. 339-347
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Genome-wide association studies (GWAS) have identified 140 Crohn's disease (CD) susceptibility loci. For most loci, the variants that cause disease are not known and the genes affected by these variants have not been identified. We aimed to identify variants that cause CD through detailed sequencing, genetic association, expression, and functional studies.METHODS: We sequenced whole exomes of 42 unrelated subjects with CD and 5 healthy subjects (controls) and then filtered single nucleotide variants by incorporating association results from meta-analyses of CD GWAS and in silico mutation effect prediction algorithms. We then genotyped 9348 subjects with CD, 2868 subjects with ulcerative colitis, and 14,567 control subjects and associated variants analyzed in functional studies using materials from subjects and controls and in vitro model systems.RESULTS: We identified rare missense mutations in PR domain-containing 1 (PRDM1) and associated these with CD. These mutations increased proliferation of T cells and secretion of cytokines on activation and increased expression of the adhesion molecule L-selectin. A common CD risk allele, identified in GWAS, correlated with reduced expression of PRDM1 in ileal biopsy specimens and peripheral blood mononuclear cells (combined P = 1.6 x 10(-8)). We identified an association between CD and a common missense variant, Val248Ala, in nuclear domain 10 protein 52 (NDP52) (P = 4.83 x 10(-9)). We found that this variant impairs the regulatory functions of NDP52 to inhibit nuclear factor kappa B activation of genes that regulate inflammation and affect the stability of proteins in Toll-like receptor pathways.CONCLUSIONS: We have extended the results of GWAS and provide evidence that variants in PRDM1 and NDP52 determine susceptibility to CD. PRDM1 maps adjacent to a CD interval identified in GWAS and encodes a transcription factor expressed by T and B cells. NDP52 is an adaptor protein that functions in selective autophagy of intracellular bacteria and signaling molecules, supporting the role of autophagy in the pathogenesis of CD.
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| 6. |
- Haas, Jan, et al.
(författare)
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Atlas of the clinical genetics of human dilated cardiomyopathy
- 2015
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 36:18, s. 1123-U43
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Tidskriftsartikel (refereegranskat)abstract
- Aim: We were able to show that targeted Next-Generation Sequencing is well suited to be applied in clinical routine diagnostics, substantiating the ongoing paradigm shift from low- to high-throughput genomics in medicine. By means of our atlas of the genetics of human DCM, we aspire to soon be able to apply our findings to the individual patient with cardiomyopathy in daily clinical practice. Numerous genes are known to cause dilated cardiomyopathy (DCM). However, until now technological limitations have hindered elucidation of the contribution of all clinically relevant disease genes to DCM phenotypes in larger cohorts. We now utilized next-generation sequencing to overcome these limitations and screened all DCM disease genes in a large cohort. Methods and results: In this multi-centre, multi-national study, we have enrolled 639 patients with sporadic or familial DCM. To all samples, we applied a standardized protocol for ultra-high coverage next-generation sequencing of 84 genes, leading to 99.1% coverage of the target region with at least 50-fold and a mean read depth of 2415. In this well characterized cohort, we find the highest number of known cardiomyopathy mutations in plakophilin-2, myosin-binding protein C-3, and desmoplakin. When we include yet unknown but predicted disease variants, we find titin, plakophilin-2, myosin-binding protein-C 3, desmoplakin, ryanodine receptor 2, desmocollin-2, desmoglein-2, and SCN5A variants among the most commonly mutated genes. The overlap between DCM, hypertrophic cardiomyopathy (HCM), and channelopathy causing mutations is considerably high. Of note, we find that >38% of patients have compound or combined mutations and 12.8% have three or even more mutations. When comparing patients recruited in the eight participating European countries we find remarkably little differences in mutation frequencies and affected genes. Conclusion: This is to our knowledge, the first study that comprehensively investigated the genetics of DCM in a large-scale cohort and across a broad gene panel of the known DCM genes. Our results underline the high analytical quality and feasibility of Next-Generation Sequencing in clinical genetic diagnostics and provide a sound database of the genetic causes of DCM.
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| 7. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Kohler, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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Mitochondrial lipids in neurodegeneration
- 2016
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Ingår i: Cell and Tissue Research. - : Springer. - 0302-766X .- 1432-0878. ; 367:1, s. 125-140
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer’s or Parkinson’s disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.
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| 9. |
- Kohler, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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The enzymatic core of the Parkinson’s disease-associated protein LRRK2 impairs mitochondrial biogenesis in aging yeast
- 2018
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media S.A.. - 1662-5099. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial dysfunction is a prominent trait of cellular decline during aging and intimately linked to neuronal degeneration during Parkinson’s disease (PD). Various proteins associated with PD have been shown to differentially impact mitochondrial dynamics, quality control and function, including the leucine-rich repeat kinase 2 (LRRK2). Here, we demonstrate that high levels of the enzymatic core of human LRRK2, harboring GTPase as well as kinase activity, decreases mitochondrial mass via an impairment of mitochondrial biogenesis in aging yeast. We link mitochondrial depletion to a global downregulation of mitochondria-related gene transcripts and show that this catalytic core of LRRK2 localizes to mitochondria and selectively compromises respiratory chain complex IV formation. With progressing cellular age, this culminates in dissipation of mitochondrial transmembrane potential, decreased respiratory capacity, ATP depletion and generation of reactive oxygen species. Ultimately, the collapse of the mitochondrial network results in cell death. A point mutation in LRRK2 that increases the intrinsic GTPase activity diminishes mitochondrial impairment and consequently provides cytoprotection. In sum, we report that a downregulation of mitochondrial biogenesis rather than excessive degradation of mitochondria underlies the reduction of mitochondrial abundance induced by the enzymatic core of LRRK2 in aging yeast cells. Thus, our data provide a novel perspective for deciphering the causative mechanisms of LRRK2-associated PD pathology.
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| 10. |
- Kohler, Verena, 1992-, et al.
(författare)
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Conjugative type IV secretion in Gram-positive pathogens : TraG, a lytic transglycosylase and endopeptidase, interacts with translocation channel protein TraM
- 2017
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Ingår i: Plasmid. - : Elsevier BV. - 0147-619X .- 1095-9890. ; 91, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- Conjugative transfer plays a major role in the transmission of antibiotic resistance in bacteria. pIP501 is a Grampositive conjugative model plasmid with the broadest transfer host-range known so far and is frequently found in Enterococcus faecalis and Enterococcus faecium clinical isolates. The pIP501 type IV secretion system is encoded by 15 transfer genes. In this work, we focus on the VirB1-like protein TraG, a modular peptidoglycan metabolizing enzyme, and the VirB8-homolog TraM, a potential member of the translocation channel. By providing full-length traG in trans, but not with a truncated variant, we achieved full recovery of wild type transfer efficiency in the traG-knockout mutant E. faecalis pIP501AtraG. With peptidoglycan digestion experiments and tandem mass spectrometry we could assign lytic transglycosylase and endopeptidase activity to TraG, with the CHAP domain alone displaying endopeptidase activity. We identified a novel interaction between TraG and TraM in a bacterial 2-hybrid assay. In addition we found that both proteins localize in focal spots at the E. faecalis cell membrane using immunostaining and fluorescence microscopy. Extracellular protease digestion to evaluate protein cell surface exposure revealed that correct membrane localization of TraM requires the transmembrane helix of TraG. Thus, we suggest an essential role for TraG in the assembly of the pIP501 type IV secretion system.
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