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Accumulation of Helicobacter pylori products, NOD1, ubiquitinated proteins and proteasome in a novel cytoplasmic structure of human gastric epithelial cells in vivo.
No full textEvidence for transepithelial dendritic cells in human H. pylori active gastritis.
No full textBackground: Despite extensive experimental investigation stressing the importance of bacterial interaction with dendritic cells (DCs), evidence regarding direct interaction of H. pylori or its virulence products with DCs in the human gastric mucosa is lacking.
Methods: Human gastric mucosa biopsies, with or without H. pylori infection and active inflammation, were investigated at light and electron microscopy level with immunocytochemical tests for bacterial products (VacA, urease, outer membrane proteins) and DC markers (DC-SIGN, CD11c, CD83) or with the DC-labeling ZnI2-OsO4 technique. Parallel tests with cultured DCs were carried out.
Results: Cells reproducing ultrastructural and cytochemical patterns of DCs were detected in the lamina propria and epithelium of heavily infected and inflamed (but not of normal or moderately inflamed) mucosa, where DC luminal endings directly contact H. pylori and take up their virulence products. Cytotoxic changes (mitochondrial swelling, cytoplasmic vacuolation, autophagy) were observed in intraepithelial DCs and reproduced in cultured DCs incubated with H. pylori broth culture filtrates to obtain intracellular accumulation of VacA and urease. Granulocytes were also seen to contact and heavily phagocytose luminal H. pylori, while macrophages remained confined to basal epithelium, though taking up bacteria and bacterial products.
Conclusion: Human DCs can enter H. pylori-infected gastric epithelium, in association with other innate immunity cells, to take up bacteria and their virulence products. This process is likely to be important for bacterial sensing and pertinent immune response, however it may also generate DC cytotoxic changes potentially hampering their function
Proteasome-Rich PaCS as an Oncofetal UPS Structure Handling Cytosolic Polyubiquitinated Proteins. In Vivo Occurrence, in Vitro Induction, and Biological Role
No full textIn this article, we outline and discuss available information on the cellular site and mechanism of proteasome interaction with cytosolic polyubiquitinated proteins and heat-shock molecules. The particulate cytoplasmic structure (PaCS) formed by barrel-like particles, closely reproducing in vivo the high-resolution structure of 26S proteasome as isolated in vitro, has been detected in a variety of fetal and neoplastic cells, from living tissue or cultured cell lines. Specific trophic factors and interleukins were found to induce PaCS during in vitro differentiation of dendritic, natural killer (NK), or megakaryoblastic cells, apparently through activation of the MAPK-ERK pathway. Direct interaction of CagA bacterial oncoprotein with proteasome was shown inside the PaCSs of a Helicobacter pylori-infected gastric epithelium, a finding suggesting a role for PaCS in CagA-mediated gastric carcinogenesis. PaCS dissolution and autophagy were seen after withdrawal of inducing factors. PaCS-filled cell blebs and ectosomes were found in some cells and may represent a potential intercellular discharge and transport system of polyubiquitinated antigenic proteins. PaCS differs substantially from the inclusion bodies, sequestosomes, and aggresomes reported in proteinopathies like Huntington or Parkinson diseases, which usually lack PaCS. The latter seems more linked to conditions of increased cell proliferation/differentiation, implying an increased functional demand to the ubiquitin−proteasome system
In vivo accumulation of Helicobacter pylori products, NOD1, ubiquitinated proteins and proteasome in a novel cytoplasmic structure.
No full textCell internalization and intracellular fate of H. pylori products/virulence factors in vivo by human gastric epithelium, the main target of H. pylori-induced pathologies (i.e., peptic ulcer and cancer), are still largely unknown. Investigating gastric endoscopic biopsies from dyspeptic patients by means of ultrastructural immunocytochemistry, here we show that, in human superficial-foveolar epithelium and its metaplastic or dysplastic foci, H. pylori virulence factors accumulated in a discrete cytoplasmic structure characterized by 13-nm-thick cylindrical particles of regular punctate-linear substructure resembling the proteasome complex in size and structure. Inside this particle-rich cytoplasmic structure (PaCS) we observed colocalization of VacA, CagA, urease and outer membrane proteins with NOD1 receptor, ubiquitin-activating enzyme E1, polyubiquitinated proteins, proteasome components and potentially oncogenic proteins like SHP2 and ERKs in human gastric epithelium. By means of electron and confocal microscopy, we demonstrate that the in vivo findings were reproduced in vitro by incubating human epithelial cell lines with H. pylori products/virulence factors. PaCSs differed from VacA-induced vacuoles, phagosomes, aggresomes or related bodies. Our data suggest that PaCS is a novel, proteasome-enriched structure arising in ribosome-rich cytoplasm at sites of H. pylori products accumulation. As a site of selective concentration of bacterial virulence factors, the ubiquitin-proteasome system and interactive proteins, PaCS is likely to modulate immune-inflammatory and proliferative responses of the gastric epithelium of potential pathologic relevance
Dysplastic histogenesis of cartilage growth plate by alteration of sulphation pathway. A transgenic model.
No full textMutations in the diastrophic dysplasia sulphate transporter
(dtdst) gene causes different forms of chondrodysplasia in the
human. The generation of a knock-in mouse strain with a mutation
in dtdst gene provides the basis to study developmental dynamics in
the epiphyseal growth plate and long bone growth after impairment
of the sulphate pathway. Our microscopical and histochemical
data demonstrate that dtdst gene impairment deeply affects tissue
organization, matrix structure, and cell differentiation in the
epiphyseal growth plate. In mutant animals, the height of the
growth plate was significantly reduced, according to a concomitant
decrease in cell density and proliferation. Although the pathway
of chondrocyte differentiation seemed complete, alteration in cell
morphology compared to normal counterparts was detected. In
the extracellular matrix, it we observed a dramatic decrease in
sulphated proteoglycans, alterations in the organization of type II
and type X collagen fibers, and premature onset of mineralization.
These data confirm the crucial role of sulphate pathway in
proteoglycan biochemistry and suggest that a disarrangement of
the extracellular matrix may be responsible for the development of
dtdts cartilage dysplasia. Moreover, we corroborated the concept
that proteoglycans not only are structural components of the
cartilage architecture, but also play a dynamic role in the regulation
of chondrocyte growth and differentiation
Chaperone molecules concentrate together with the ubiquitin–proteasome system inside particulate cytoplasmic structures: possible role in metabolism of misfolded proteins
No full textUbiquitin-proteasome system (UPS) proteins and proteolytic activity are localized in a recently identified cytoplasmic structure characterized by accumulation of barrel-like particles, which is known as the particulate cytoplasmic structure (PaCS). PaCSs have been detected in neoplastic, preneoplastic, chronically infected, and fetal cells, which produce high amounts of misfolded proteins to be degraded by the UPS. Chaperone molecules are crucial in the early stages of handling misfolded proteins; therefore, we searched for these molecules in PaCSs. Heat shock proteins (Hsp), Hsp90, Hsp70, Hsp40, and Bcl-2-associated athanogene (Bag)3 chaperones, although not Bag6, were selectively concentrated into PaCSs of several cell lines and ex vivo fetal or neoplastic cells. Present findings point to PaCSs as an integrated, active UPS center well equipped for metabolism of misfolded proteins, especially in cells under physiological (fetal development) or pathological (neoplasia or inflammation) stress
Seeing is believing: evidence of a novel cytoplasmic structure containing functional proteasome and inducible by cytokines/trophic factors.
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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