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  • 1
    Language: English
    In: eLife, 2017-05-19, Vol.6
    Description: Intracellular membrane fusion mediates diverse processes including cell growth, division and communication. Fusion involves complex formation between SNARE proteins anchored to adjacent membranes. How and in what form interacting SNARE proteins reach their sites of action is virtually unknown. We have addressed this problem in the context of plant cell division in which a large number of TGN-derived membrane vesicles fuse with one another to form the partitioning membrane. Blocking vesicle formation at the TGN revealed -SNARE complexes. These inactive cytokinetic SNARE complexes were already assembled at the endoplasmic reticulum and, after passage through Golgi/TGN to the cell division plane, transformed into fusogenic SNARE complexes. This mode of trafficking might ensure delivery of large stoichiometric quantities of SNARE proteins required for forming the partitioning membrane in the narrow time frame of plant cytokinesis. Such long-distance trafficking of inactive SNARE complexes would also facilitate directional growth processes during cell differentiation.
    Subject(s): Endoplasmic Reticulum - metabolism ; Arabidopsis - physiology ; Cell Membrane - metabolism ; Cytokinesis ; SNARE Proteins - metabolism ; Protein Transport ; Physiological aspects ; Cell membranes ; Observations ; Arabidopsis ; Endoplasmic reticulum ; Proteins ; Membrane fusion ; Cell division ; Intracellular signalling ; Membrane vesicles ; SNAP receptors ; Mutation ; Molecular biology ; Cell interactions ; Golgi cells ; Plant Biology ; cytokinesis ; A. thaliana ; Short Report ; SNARE complex ; membrane traffic ; Cell Biology ; membrane fusion
    ISSN: 2050-084X
    E-ISSN: 2050-084X
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 2
    Language: English
    In: Pediatric nephrology (Berlin, West), 2020-05, Vol.35 (5), p.829-842
    Description: To date, there is insufficient knowledge about crescentic glomerulonephritis (cGN), the most frequent immunologic cause of acute kidney injury in children. Over a period of 16 years, we retrospectively analyzed kidney biopsy results, the clinical course, and laboratory data in 60 pediatric patients diagnosed with cGN. The underlying diseases were immune complex GN (n = 45/60, 75%), including IgA nephropathy (n = 19/45, 42%), lupus nephritis (n = 10/45, 22%), Henoch-Schoenlein purpura nephritis (n = 7/45, 16%) and post-infectious GN (n = 7/45, 16%), ANCA-associated pauci-immune GN (n = 10/60, 17%), and anti-glomerular basement-membrane GN (n = 1/60, 2%). Patient CKD stages at time of diagnosis and at a median of 362 days (range 237-425) were CKD I: n = 13/n = 29, CKD II: n = 15/n = 9, CKD III: n = 16/n = 7, CKD IV: n = 3/n = 3, CKD V: n = 13/n = 5. Course of cGN was different according to class of cGN, duration of disease from first clinical signs to diagnosis of cGN by biopsy, percentage of crescentic glomeruli, amount of tubular atrophy/interstitial fibrosis and necrosis on renal biopsy, gender, age, nephrotic syndrome, arterial hypertension, dialysis at presentation, and relapse. Forty-eight/60 children were treated with ≥ 5 (methyl-) prednisolone pulses and 53 patients received oral prednis(ol)one in combination with mycophenolate mofetil (n = 20), cyclosporine A (n = 20), and/or cyclophosphamide (n = 6), rituximab (n = 5), azathioprine (n = 2), tacrolimus (n = 1), and plasmapheresis/immunoadsorption (n = 5). The treatment success of cGN is dependent on early diagnosis and aggressive therapy, as well as on the percentage of crescentic glomeruli on renal biopsy and on the underlying type of cGN. CsA and MMF seem to be effective alternatives to cyclophosphamide.
    Subject(s): Glomerulonephritis - therapy ; Prednisolone - administration & dosage ; Prognosis ; Humans ; Child, Preschool ; Glomerulonephritis - diagnosis ; Male ; Antibodies, Antineutrophil Cytoplasmic - immunology ; Necrosis - immunology ; Glomerular Basement Membrane - pathology ; Female ; Retrospective Studies ; Acute Kidney Injury - immunology ; Necrosis - diagnosis ; Drug Therapy, Combination ; Child ; Immunosuppressive Agents - administration & dosage ; Severity of Illness Index ; Glomerular Filtration Rate ; Necrosis - complications ; Glomerulonephritis - immunology ; Treatment Outcome ; Combined Modality Therapy ; Glomerulonephritis - complications ; Pulse Therapy, Drug ; Plasmapheresis ; Acute Kidney Injury - mortality ; Biopsy ; Necrosis - therapy ; Acute Kidney Injury - diagnosis ; Adolescent ; Fibrosis ; Glomerular Basement Membrane - immunology ; Acute Kidney Injury - therapy ; Antibodies, Antineutrophil Cytoplasmic - blood ; Glomerulonephritis ; Care and treatment ; Diagnosis ; Pediatric research
    ISSN: 0931-041X
    E-ISSN: 1432-198X
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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  • 3
    Language: English
    In: eLife, 2014-04-08, Vol.3, p.e02131-e02131
    Description: Membrane trafficking is essential to fundamental processes in eukaryotic life, including cell growth and division. In plant cytokinesis, post-Golgi trafficking mediates a massive flow of vesicles that form the partitioning membrane but its regulation remains poorly understood. Here, we identify functionally redundant Arabidopsis ARF guanine-nucleotide exchange factors (ARF-GEFs) BIG1-BIG4 as regulators of post-Golgi trafficking, mediating late secretion from the trans-Golgi network but not recycling of endocytosed proteins to the plasma membrane, although the TGN also functions as an early endosome in plants. In contrast, BIG1-4 are absolutely required for trafficking of both endocytosed and newly synthesized proteins to the cell-division plane during cytokinesis, counteracting recycling to the plasma membrane. This change from recycling to secretory trafficking pathway mediated by ARF-GEFs confers specificity of cargo delivery to the division plane and might thus ensure that the partitioning membrane is completed on time in the absence of a cytokinesis-interphase checkpoint. DOI: http://dx.doi.org/10.7554/eLife.02131.001.
    Subject(s): Arabidopsis Proteins - metabolism ; Endocytosis ; Cell Division ; Golgi Apparatus - metabolism ; Arabidopsis Proteins - secretion ; Arabidopsis - metabolism ; Protein Transport ; Seeds ; Cytokinesis ; Guanine ; Golgi apparatus ; Proteins ; Microscopy ; Phylogenetics ; Membrane trafficking ; Physiology ; Software ; Flowers & plants ; Recycling ; Molecular biology ; Guanine nucleotide exchange factor ; Localization ; Plant Biology ; ARF-GEF ; secretion ; Arabidopsis ; cell division ; post-Golgi trafficking ; recycling ; gegulation of vesicle traffic ; Cell Biology
    ISSN: 2050-084X
    E-ISSN: 2050-084X
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 4
    Language: English
    In: Development (Cambridge), 2004-04-01, Vol.131 (7), p.1619-1628
    Description: Basement membranes are specialized extracellular matrices consisting of tissue-specific organizations of multiple matrix molecules and serve as structural barriers as well as substrates for cellular interactions. The network of collagen IV is thought to define the scaffold integrating other components such as, laminins, nidogens or perlecan, into highly organized supramolecular architectures. To analyze the functional roles of the major collagen IV isoform α1(IV) 2 α2(IV) for basement membrane assembly and embryonic development, we generated a null allele of the Col4a1/2 locus in mice, thereby ablating both α-chains. Unexpectedly, embryos developed up to E9.5 at the expected Mendelian ratio and showed a variable degree of growth retardation. Basement membrane proteins were deposited and assembled at expected sites in mutant embryos, indicating that this isoform is dispensable for matrix deposition and assembly during early development. However, lethality occurred between E10.5-E11.5, because of structural deficiencies in the basement membranes and finally by failure of the integrity of Reichert's membrane. These data demonstrate for the first time that collagen IV is fundamental for the maintenance of integrity and function of basement membranes under conditions of increasing mechanical demands, but dispensable for deposition and initial assembly of components. Taken together with other basement membrane protein knockouts, these data suggest that laminin is sufficient for basement membrane-like matrices during early development, but at later stages the specific composition of components including collagen IV defines integrity, stability and functionality.
    Subject(s): Collagen Type IV - metabolism ; Basement Membrane - ultrastructure ; Embryo, Mammalian - pathology ; Membrane Glycoproteins - metabolism ; Blood Vessels - metabolism ; Basement Membrane - metabolism ; Gestational Age ; Blood Vessels - cytology ; Mice, Knockout ; Placenta - metabolism ; Pregnancy ; Embryo, Mammalian - physiology ; Animals ; Protein Isoforms - metabolism ; Embryo, Mammalian - anatomy & histology ; Placenta - cytology ; Placenta - pathology ; Collagen Type IV - genetics ; Female ; Mice ; Laminin - metabolism ; Transgenes ; Protein Isoforms - genetics
    ISSN: 0950-1991
    E-ISSN: 1477-9129
    Source: HighWire Press (Free Journals)
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: The Plant cell, 2009-12-01, Vol.21 (12), p.3984-4001
    Description: Plastid-targeted proteins pass through the cytosol as unfolded precursors. If proteins accumulate in the cytosol, they can form nonspecific aggregates that cause severe cellular damage. Here, we demonstrate that high levels of plastid precursors are degraded through the ubiquitin-proteasome system (UPS) in Arabidopsis thaliana cells. The cytosolic heat shock protein cognate 70-4 (Hsc70-4) and E3 ligase carboxy terminus of HscTO-interacting protein (CHIP) were highly induced in plastid protein import2 plants, which had a T-DNA insertion at Toc159 and showed an albino phenotype and a severe defect in protein import into chloroplasts. Hsc70-4 and CHIP together mediated plastid precursor degradation when import-defective chloroplast-targeted reporter proteins were transiently expressed in protoplasts. Hsc70-4 recognized specific sequence motifs in transit peptides and thereby led to precursor degradation through the UPS. CHIP, which interacted with Hsc70-4, functioned as an E3 ligase in the Hsc70-4-mediated protein degradation. The physiological role of Hsc70-4 was confirmed by analyzing Hsc70-4 RNA interfernce plants in an hsc70-1 mutant background. Plants with lower Hsc70 levels exhibited abnormal embryogenesis, resulting in defective seedlings that displayed high levels of reactive oxygen species and monoubiquitinated Lhcb4 precursors. We propose that Hsc70-4 and CHIP mediate plastid-destined precursor degradation to prevent cytosolic precursor accumulation and thereby play a critical role in embryogenesis.
    Subject(s): Proteins ; Protein isoforms ; Chloroplasts ; Gels ; Reverse transcriptase polymerase chain reaction ; Protoplasts ; Antibodies ; Protein precursors ; Plastids ; Plant cells ; Oligonucleotide Array Sequence Analysis ; Plants, Genetically Modified - genetics ; HSC70 Heat-Shock Proteins - metabolism ; Ubiquitin - metabolism ; Ubiquitin-Protein Ligases - metabolism ; Phylogeny ; RNA, Plant - genetics ; Chloroplasts - metabolism ; Protein Folding ; Arabidopsis - metabolism ; Protein Precursors - metabolism ; Arabidopsis - genetics ; Arabidopsis Proteins - metabolism ; DNA, Bacterial - genetics ; Plants, Genetically Modified - metabolism ; Mutagenesis, Insertional ; Protein Processing, Post-Translational ; Proteasome Endopeptidase Complex - metabolism ; Arabidopsis thaliana ; Ubiquitin ; Heat shock proteins ; Physiological aspects ; Plant embryology ; Research ; Properties
    ISSN: 1040-4651
    E-ISSN: 1532-298X
    Source: American Society of Plant Biologists
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: PubMed Central
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  • 6
    Language: English
    In: The FEBS journal, 2007-06, Vol.274 (11), p.2897-2908
    Description: Basement membranes are sheets of extracellular matrix that separate epithelia from connective tissues and outline muscle fibers and the endothelial lining of blood vessels. A major function of basement membranes is to establish and maintain stable tissue borders, exemplified by frequent vascular breaks and a disrupted pial and retinal surface in mice with mutations or deletions of basement membrane proteins. To directly measure the biomechanical properties of basement membranes, chick and mouse inner limiting membranes were examined by atomic force microscopy. The inner limiting membrane is located at the retinal‐vitreal junction and its weakening due to basement membrane protein mutations leads to inner limiting membrane rupture and the invasion of retinal cells into the vitreous. Transmission electron microscopy and western blotting has shown that the inner limiting membrane has an ultrastructure and a protein composition typical for most other basement membranes and, thus, provides a suitable model for determining their biophysical properties. Atomic force microscopy measurements of native chick basement membranes revealed an increase in thickness from 137 nm at embryonic day 4 to 402 nm at embryonic day 9, several times thicker that previously determined by transmission electron microscopy. The change in basement membrane thickness was accompanied by a large increase in apparent Young's modulus from 0.95 MPa to 3.30 MPa. The apparent Young's modulus of the neonatal and adult mouse retinal basement membranes was in a similar range, with 3.81 MPa versus 4.07 MPa, respectively. These results revealed that native basement membranes are much thicker than previously determined. Their high mechanical strength explains why basement membranes are essential in stabilizing blood vessels, muscle fibers and the pial border of the central nervous system.
    Subject(s): eye development ; basement membrane ; atomic force microscopy ; basal lamina ; extracellular matrix ; Biomechanical Phenomena ; Animals ; Basement Membrane - embryology ; Mice, Mutant Strains ; Desiccation ; Bruch Membrane - physiology ; Elasticity ; Microscopy, Atomic Force ; Basement Membrane - physiology ; Bruch Membrane - ultrastructure ; Mice ; Chick Embryo
    ISSN: 1742-464X
    E-ISSN: 1742-4658
    Source: Hellenic Academic Libraries Link
    Source: Academic Search Ultimate
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  • 7
    Language: English
    In: The EMBO journal, 2021-03-15, Vol.40 (6), p.e105543-n/a
    Description: Influenza A virus (IAV) and SARS‐CoV‐2 (COVID‐19) cause pandemic infections where cytokine storm syndrome and lung inflammation lead to high mortality. Given the high social and economic cost of respiratory viruses, there is an urgent need to understand how the airways defend against virus infection. Here we use mice lacking the WD and linker domains of ATG16L1 to demonstrate that ATG16L1‐dependent targeting of LC3 to single‐membrane, non‐autophagosome compartments – referred to as non‐canonical autophagy – protects mice from lethal IAV infection. Mice with systemic loss of non‐canonical autophagy are exquisitely sensitive to low‐pathogenicity IAV where extensive viral replication throughout the lungs, coupled with cytokine amplification mediated by plasmacytoid dendritic cells, leads to fulminant pneumonia, lung inflammation and high mortality. IAV was controlled within epithelial barriers where non‐canonical autophagy reduced IAV fusion with endosomes and activation of interferon signalling. Conditional mouse models and ex vivo analysis showed that protection against IAV infection of lung was independent of phagocytes and other leucocytes. This establishes non‐canonical autophagy in airway epithelial cells as a novel innate defence that restricts IAV infection and lethal inflammation at respiratory surfaces. SYNOPSIS Non‐canonical functions of the autophagy protein ATG16L1 are mediated by its C‐terminal WD domain. Here, mice expressing WD domain‐lacking ATG16L1 are found to be highly sensitive to influenza virus infection, resulting in cytokine storm and lethal pneumonia. The WD domain of ATG16L1 prevents lethal infection by influenza A virus. Infection is controlled by epithelial cells and is independent of phagocytic cells. Non‐canonical ATG16L1 function reduces interferon signalling by slowing virus endocytosis and fusion with endosomal membranes. Deletion of WD domain mediating non‐canonical functions of ATG16L1 sensitizes mice to cytokine storm and lethal pneumonia upon influenza infection.
    Subject(s): influenza ; cytokine storm ; non‐canonical autophagy ; intrinsic defence ; ATG16L1 WD Domain ; Sequence Deletion ; Cytokines - metabolism ; Microtubule-Associated Proteins - metabolism ; Alveolar Epithelial Cells - virology ; Alveolar Epithelial Cells - metabolism ; Autophagy ; Chick Embryo ; Autophagy-Related Proteins - chemistry ; Orthomyxoviridae Infections - genetics ; Animals ; Orthomyxoviridae Infections - mortality ; Virus Replication ; Dogs ; Madin Darby Canine Kidney Cells ; Influenza A virus - pathogenicity ; Protein Domains ; Mice ; Autophagy-Related Proteins - genetics ; Autophagy-Related Proteins - metabolism ; Orthomyxoviridae Infections - immunology
    ISSN: 0261-4189
    E-ISSN: 1460-2075
    Source: Alma/SFX Local Collection
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  • 8
    Language: English
    In: Frontiers in microbiology, 2020, Vol.11, p.57-57
    Description: Gram-negative bacteria ubiquitously produce and release nano-size, non-replicative outer membrane vesicles (OMVs). In the gastrointestinal (GI-) tract, OMVs generated by members of the intestinal microbiota are believed to contribute to maintaining the intestinal microbial ecosystem and mediating bacteria-host interactions, including the delivery of bacterial effector molecules to host cells to modulate their physiology. Bacterial OMVs have also been found in the bloodstream although their origin and fate are unclear. Here we have investigated the interactions between OMVs produced by the major human gut commensal bacterium, (Bt), with cells of the GI-tract. Using a combination of culture systems including intestinal epithelial organoids and imaging we show that intestinal epithelial cells principally acquire Bt OMVs via dynamin-dependent endocytosis followed by intracellular trafficking to LAMP-1 expressing endo-lysosomal vesicles and co-localization with the perinuclear membrane. We observed that Bt OMVs can also transmigrate through epithelial cells via a paracellular route with imaging demonstrating that within hours of oral administration Bt OMVs can be detected in systemic tissues and in particular, the liver. Our findings raise the intriguing possibility that OMVs may act as a long-distance microbiota-host communication system.
    Subject(s): microvesicles ; outer membrane vesicles ; Bacteroides thetaiotaomicron ; GI-tract ; bacterial extracellular vesicles ; gut microbiota
    ISSN: 1664-302X
    E-ISSN: 1664-302X
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 9
    Language: English
    In: The Journal of cell biology, 2007-05-07, Vol.177 (3), p.527-538
    Description: Cell migration in wound healing and disease is critically dependent on integration with the extracellular matrix, but the receptors that couple matrix topography to migratory behavior remain obscure. Using nano-engineered fibronectin surfaces and cellderived matrices, we identify syndecan-4 as a key signaling receptor determining directional migration. In wild-type fibroblasts, syndecan-4 mediates the matrix-induced protein kinase Ca (PKCa)-dependent activation of Racl and localizes Racl activity and membrane protrusion to the leading edge of the cell, resulting in persistent migration. In contrast, syndecan-4-null fibroblasts migrate randomly as a result of high delocalized Racl activity, whereas cells expressing a syndecan-4 cytodomain mutant deficient in PKCa regulation fail to localize active Racl to points of matrix engagement and consequently fail to recognize and respond to topographical changes in the matrix.
    Subject(s): Receptors ; Cell lines ; Fibrosis ; Cell adhesion ; Fibroblasts ; Ligands ; Stripes ; Focal adhesions ; Physiological regulation ; Integrins ; Fibronectins ; Extracellular Matrix ; Protein Kinase C-alpha - metabolism ; Syndecan-4 - metabolism ; Syndecan-4 - genetics ; Cells, Cultured ; rac GTP-Binding Proteins - metabolism ; Neuropeptides - metabolism ; Protein Structure, Tertiary - genetics ; Cell Movement - genetics ; Mice, Knockout ; Animals ; rac GTP-Binding Proteins - genetics ; Fibroblasts - cytology ; Mice ; Mutation ; Neuropeptides - genetics ; rac1 GTP-Binding Protein ; Enzyme Activation - genetics ; Protein Kinase C-alpha - deficiency ; Fibroblasts - metabolism
    ISSN: 0021-9525
    E-ISSN: 1540-8140
    Source: HighWire Press (Free Journals)
    Source: Rockefeller University Press
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: PubMed Central
    Source: Alma/SFX Local Collection
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  • 10
    Language: English
    In: Development (Cambridge), 2006-08-15, Vol.133 (16), p.3245-3254
    Description: Radial glial cells have been shown to act as neuronal precursors in the developing cortex and to maintain their radial processes attached to the basement membrane (BM) during cell division. Here, we examined a potential role of direct signalling from the BM to radial glial cells in three mouse mutants where radial glia attachment to the BM is disrupted. This is the case if the nidogen-binding site of the laminin γ1 chain is mutated, in the absence of α6 integrin or of perlecan, an essential BM component. Surprisingly, cortical radial glial cells lacking contact to the BM were not affected in their proliferation, interkinetic nuclear migration, orientation of cell division and neurogenesis. Only a small subset of precursors was located ectopically within the cortical parenchyma. Notably, however, neuronal subtype composition was severely disturbed at late developmental stages (E18) in the cortex of the laminin γ1III4 -/- mice. Thus, although BM attachment seems dispensable for precursor cells, an intact BM is required for adequate neuronal composition of the cerebral cortex.
    Subject(s): Cell Division - genetics ; Cell Proliferation ; Membrane Glycoproteins - metabolism ; Integrin alpha6 - genetics ; Neurons - cytology ; Binding Sites - genetics ; Cerebral Cortex - cytology ; Cell Movement - genetics ; Laminin - genetics ; Cell Differentiation - genetics ; Neuroglia - cytology ; Animals ; Heparan Sulfate Proteoglycans - genetics ; Mice, Mutant Strains ; Cerebral Cortex - growth & development ; Basement Membrane - physiology ; Mice ; Mutation ; Active Transport, Cell Nucleus - genetics ; Integrin alpha6 ; Basement Membrane ; Neurons ; Neuroglia ; Biochemistry, Molecular Biology ; Cerebral Cortex ; Life Sciences ; Laminin ; Cell Division ; Heparan Sulfate Proteoglycans ; Cell Differentiation ; Active Transport, Cell Nucleus ; Membrane Glycoproteins ; Molecular biology ; Binding Sites ; Cell Movement
    ISSN: 0950-1991
    ISSN: 0951-1991
    E-ISSN: 1477-9129
    Source: HighWire Press (Free Journals)
    Source: Alma/SFX Local Collection
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