scholarly journals Contribution of syndecans to cellular uptake and fibrillation of α-synuclein and tau

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Anett Hudák ◽  
Erzsébet Kusz ◽  
Ildikó Domonkos ◽  
Katalin Jósvay ◽  
Alpha Tom Kodamullil ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cellular Uptake ◽  
Scientific Evidence ◽  
Heparan Sulfate Proteoglycans ◽  
The Other ◽  
Misfolded Protein ◽  
Tau Pathology ◽  
Cellular Models ◽  
Molecular Events ◽  
Protein Fibrils

Abstract Scientific evidence suggests that α-synuclein and tau have prion-like properties and that prion-like spreading and seeding of misfolded protein aggregates constitutes a central mechanism for neurodegeneration. Heparan sulfate proteoglycans (HSPGs) in the plasma membrane support this process by attaching misfolded protein fibrils. Despite of intense studies, contribution of specific HSPGs to seeding and spreading of α-synuclein and tau has not been explored yet. Here we report that members of the syndecan family of HSPGs mediate cellular uptake of α-synuclein and tau fibrils via a lipid-raft dependent and clathrin-independent endocytic route. Among syndecans, the neuron predominant syndecan-3 exhibits the highest affinity for both α-synuclein and tau. Syndecan-mediated internalization of α-synuclein and tau depends heavily on conformation as uptake via syndecans start to dominate once fibrils are formed. Overexpression of syndecans, on the other hand, reduces cellular uptake of monomeric α-synuclein and tau, yet exerts a fibril forming effect on both proteins. Data obtained from syndecan overexpressing cellular models presents syndecans, especially the neuron predominant syndecan-3, as important mediators of seeding and spreading of α-synuclein and tau and reveal how syndecans contribute to fundamental molecular events of α-synuclein and tau pathology.

Die Anämie bei malignen Tumorerkrankungen

1989 ◽  
Vol 28 (05) ◽  
pp. 193-200 ◽  
Author(s):  
E. Aulbert
Keyword(s):  
Cellular Uptake ◽  
Tumor Tissue ◽  
Malignant Tumors ◽  
The Other ◽  
Novikoff Hepatoma ◽  
Cellular Accumulation ◽  
Tumor Mass ◽  
Proliferation Activity ◽  
Morris Hepatoma ◽  
Cellular Incorporation

Cellular uptake of 67Ga-labelled transferrin by the tumor tissue was studied in rats with tumors of different malignancy and different tumor mass using the slowly growing Morris hepatoma 5123C, the moderately growing Novikoff hepatoma and the very fast and aggressive Yoshida hepatoma AH130. The cellular accumulation of 67Ga-transferrin was found to correlate with the proliferation activity of the tumor. The 67Ga-transferrin concentration in the very fast growing Yoshida hepatoma was 4.8 times higher than the concentration in the slowly growing Morris hepatoma. The uptake of 67Ga-transferrin by the tumors resulted in a faster disappearance of circulating 67Ga-transferrin from the blood. The rate of disappearance correlated with the proliferation activity and the spread of the tumors. Using tumors of identical size the elimination of 67Ga-transferrin from the blood was much faster in the rats with Yoshida hepatoma than in those with the slowly growing Morris hepatoma. On the other hand, using tumors of different tumor size it could be demonstrated that the rate of disappearance of 67Ga-transferrin from the blood correlated directly with tumor mass. It is concluded that cellular incorporation of transferrin within the tumor cells results in a loss of circulating transferrin, which correlates with tumor mass and proliferation of tumor. This mechanism is supposed to be the cause for the hypotransferrinemia seen in patients with malignant tumors.

Do we form or deform? Qualitative Investigation in Public Hospitals of Madrid

2019 ◽  
Author(s):  
María Jesús Gómez Camuñas ◽  
Purificación González Villanueva
Keyword(s):  
Participant Observation ◽  
Scientific Evidence ◽  
Theory And Practice ◽  
Public Hospitals ◽  
The Other ◽  
The Novel ◽  
Business Growth ◽  
Small Hospital ◽  
Student Learn ◽  
Depth Interviews

<div><i>Background</i>: the creative capacities and the knowledge of the employees are components of the intellectual capital of the company; hence, their training is a key activity to achieve the objectives and business growth. <i>Objective</i>: To understand the meaning of learning in the hospital from the experiences of its participants through the inquiry of meanings. <i>Method</i>: Qualitative design with an ethnographic approach, which forms part of a wider research, on organizational culture; carried out mainly in 2 public hospitals of the Community of Madrid. The data has been collected for thirteen months. A total of 23 in-depth interviews and 69 field sessions have been conducted through the participant observation technique. <i>Results</i>: the worker and the student learn from what they see and hear. The great hospital offers an unregulated education, dependent on the professional, emphasizing that they learn everything. Some transmit the best and others, even the humiliating ones, use them for dirty jobs, focusing on the task and nullifying the possibility of thinking. They show a reluctant attitude to teach the newcomer, even if they do, they do not have to oppose their practice. In short, a learning in the variability, which produces a rupture between theory and practice; staying with what most convinces them, including negligence, which affects the patient's safety. In the small hospital, it is a teaching based on a practice based on scientific evidence and personalized attention, on knowing the other. Clearly taught from the reception, to treat with caring patience and co-responsibility in the care. The protagonists of both scenarios agree that teaching and helping new people establish lasting and important personal relationships to feel happy and want to be in that service or hospital. <i>Conclusion</i>: There are substantial differences related to the size of the center, as to what and how the student and the novel professional are formed. At the same time that the meaning of value that these health organizations transmit to their workers is inferred through the training, one orienting to the task and the other to the person, either patient, professional or pupil and therefore seeking the common benefit.</div>

Conflicting Health-Related Scientific Evidence in News Reports: Effects of Hedging and Presentation Format on Perceived Issue Uncertainty and Scientists’ and Journalists’ Credibility

2019 ◽  
Author(s):  
Hui Zhang
Keyword(s):  
Health Communication ◽  
Scientific Evidence ◽  
The Other ◽  
Presentation Format ◽  
News Article ◽  
Online Experiment ◽  
News Reports ◽  
Conflicting Evidence ◽  
Health Related

Introduction: This study examined effects of two journalistic practices in reporting conflicting scientific evidence, hedging and presentation format, on scientists’ and journalists’ credibility and issue uncertainty. Methods: An online experiment was conducted using students from a western U.S. university. Hedging was manipulated as reporting methodological limitations versus not reporting the limitations in news articles covering the conflict. Presentation format was manipulated as using a single news article to report both sides of the conflict versus using double articles with one side of the conflict in one article and the other side in the other article. Results: The study found that perceived issue uncertainty was higher in hedged news articles than that in non-hedged articles; presentation format did not affect people’s perceived issue uncertainty. For scientists’ credibility (both competence and trustworthiness), this study found that it was lower in the single-article format than that in the double-article format; for journalists’ credibility, this study found that journalists’ trustworthiness in the two formats did not vary, but their competence was lower in the double-article format than that in the single-article format. Conclusion: This study contributes to the field of science and health communication by examining effects of presentation format used in communicating conflicting health-related scientific evidence and by examining effects of communicating scientific limitations in a context where conflicting evidence exists. Keywords: conflicting scientific evidence, hedging, presentation format, scientists’ credibility, journalists’ credibility

scholarly journals Chromatin Manipulation and Editing: Challenges, New Technologies and Their Use in Plants

2021 ◽  
Vol 22 (2) ◽  
pp. 512
Author(s):  
Kateryna Fal ◽  
Denisa Tomkova ◽  
Gilles Vachon ◽  
Marie-Edith Chabouté ◽  
Alexandre Berr ◽  
...  
Keyword(s):  
Cell Fate ◽  
Dna Sequence ◽  
Zinc Finger ◽  
Chromatin Structure ◽  
New Technologies ◽  
Dna Interaction ◽  
The Other ◽  
Proof Of Concept ◽  
Epigenetic Marks ◽  
Molecular Events

An ongoing challenge in functional epigenomics is to develop tools for precise manipulation of epigenetic marks. These tools would allow moving from correlation-based to causal-based findings, a necessary step to reach conclusions on mechanistic principles. In this review, we describe and discuss the advantages and limits of tools and technologies developed to impact epigenetic marks, and which could be employed to study their direct effect on nuclear and chromatin structure, on transcription, and their further genuine role in plant cell fate and development. On one hand, epigenome-wide approaches include drug inhibitors for chromatin modifiers or readers, nanobodies against histone marks or lines expressing modified histones or mutant chromatin effectors. On the other hand, locus-specific approaches consist in targeting precise regions on the chromatin, with engineered proteins able to modify epigenetic marks. Early systems use effectors in fusion with protein domains that recognize a specific DNA sequence (Zinc Finger or TALEs), while the more recent dCas9 approach operates through RNA-DNA interaction, thereby providing more flexibility and modularity for tool designs. Current developments of “second generation”, chimeric dCas9 systems, aiming at better targeting efficiency and modifier capacity have recently been tested in plants and provided promising results. Finally, recent proof-of-concept studies forecast even finer tools, such as inducible/switchable systems, that will allow temporal analyses of the molecular events that follow a change in a specific chromatin mark.

scholarly journals Calmodulin-microtubule association in cultured mammalian cells.

1984 ◽  
Vol 98 (3) ◽  
pp. 904-910 ◽  
Author(s):  
W J Deery ◽  
A R Means ◽  
B R Brinkley
Keyword(s):  
Plasma Membrane ◽  
Mammalian Cells ◽  
Cell System ◽  
The Other ◽  
Microtubule Assembly ◽  
Cytoplasmic Microtubule ◽  
Hypotonic Treatment ◽  
Cytoplasmic Microtubules ◽  
Triton X ◽  
Ca Sensitivity

A Triton X-100-lysed cell system has been used to identify calmodulin on the cytoskeleton of 3T3 and transformed SV3T3 cells. By indirect immunofluorescence, calmodulin was found to be associated with both the cytoplasmic microtubule complex and the centrosomes. A number of cytoplasmic microtubules more resistant to disassembly upon either cold (0-4 degrees C) or hypotonic treatment, as well as following dilution have been identified. Most of the stable microtubules appeared to be associated with the centrosome at one end and with the plasma membrane at the other end. These microtubules could be induced to depolymerize, however, by micromolar Ca++ concentrations. These data suggest that, by interacting directly with the microtubule, calmodulin may influence microtubule assembly and ensure the Ca++-sensitivity of both mitotic and cytoplasmic microtubules.

scholarly journals Effects of cytoplasmic acidification on clathrin lattice morphology.

1989 ◽  
Vol 108 (2) ◽  
pp. 401-411 ◽  
Author(s):  
J Heuser
Keyword(s):  
Plasma Membrane ◽  
Cultured Cells ◽  
Membrane Receptors ◽  
The Other ◽  
Culture Dish ◽  
Initial Curvature ◽  
Internal Ph ◽  
Cytoplasmic Acidification

Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.

scholarly journals Role of the Endocytic Machinery in the Sorting of Lysosome-associated Membrane Proteins

2005 ◽  
Vol 16 (9) ◽  
pp. 4231-4242 ◽  
Author(s):  
Katy Janvier ◽  
Juan S. Bonifacino
Keyword(s):  
Plasma Membrane ◽  
Coat Protein ◽  
Membrane Proteins ◽  
Adaptor Protein ◽  
The Other ◽  
Sorting Signals ◽  
Efficient Delivery ◽  
Endocytic Machinery

The limiting membrane of the lysosome contains a group of transmembrane glycoproteins named lysosome-associated membrane proteins (Lamps). These proteins are targeted to lysosomes by virtue of tyrosine-based sorting signals in their cytosolic tails. Four adaptor protein (AP) complexes, AP-1, AP-2, AP-3, and AP-4, interact with such signals and are therefore candidates for mediating sorting of the Lamps to lysosomes. However, the role of these complexes and of the coat protein, clathrin, in sorting of the Lamps in vivo has either not been addressed or remains controversial. We have used RNA interference to show that AP-2 and clathrin—and to a lesser extent the other AP complexes—are required for efficient delivery of the Lamps to lysosomes. Because AP-2 is exclusively associated with plasma membrane clathrin coats, our observations imply that a significant population of Lamps traffic via the plasma membrane en route to lysosomes.

scholarly journals Distinct glycosaminoglycan chain length and sulfation patterns required for cellular uptake of Tau, Aβ, and α-Synuclein

2017 ◽  
Author(s):  
Barbara E. Stopschinski ◽  
Brandon B. Holmes ◽  
Gregory M. Miller ◽  
Jaime Vaquer-Alicea ◽  
Linda C. Hsieh-Wilson ◽  
...  
Keyword(s):  
Cell Surface ◽  
Neurodegenerative Diseases ◽  
Heparan Sulfate ◽  
Chain Length ◽  
Cellular Uptake ◽  
Genetic Manipulation ◽  
Heparan Sulfate Proteoglycans ◽  
Cell Uptake ◽  
Major Genes

AbstractTranscellular propagation of aggregate “seeds” has been proposed to mediate progression of neurodegenerative diseases in tauopathies and α-synucleinopathies. We have previously determined that tau and α-synuclein aggregates bind heparan sulfate proteoglycans (HSPGs) on the cell surface. This mediates uptake and intracellular seeding. The specificity and mode of binding to HSPGs has been unknown. We used modified heparins to determine the size and sulfation requirements of glycosaminoglycan (GAGs) binding to aggregates in biochemical and cell uptake and seeding assays. Aggregates of tau require a precise GAG architecture with defined sulfate moieties in the N- and 6-O-positions, whereas α-synuclein and Aβ rely slightly more on overall charge on the GAGs. To determine the genetic requirements for aggregate uptake, we individually knocked out the major genes of the HSPG synthesis pathway using CRISPR/Cas9 in HEK293T cells. Knockout of EXT1, EXT2 and EXTL3, N-sulfotransferase (NDST1), and 6-O-sulfotransferase (HS6ST2) significantly reduced tau uptake. α-Synuclein was not sensitive to HS6ST2 knockout. Good correlation between pharmacologic and genetic manipulation of GAG binding by tau and α-synuclein indicates specificity that may help elucidate a path to mechanism-based inhibition of transcellular propagation of pathology.

scholarly journals Morphological Alterations of CAD Cells Overexpressing AKT1

2020 ◽  
Vol 26 (S2) ◽  
pp. 1354-1358
Author(s):  
James Wachira
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Cell Survival ◽  
Fluorescent Protein ◽  
Morphological Changes ◽  
Protein Localization ◽  
Signal Transduction Pathways ◽  
Morphological Alterations ◽  
Cellular Models ◽  
Cad Cells

AbstractCAD cells are neuronal cells used in studies of cell differentiation and in cellular models of neuropathology. When cultured in differentiation medium, CAD cells exhibit characteristics of mature neurons including the generation of action potential. In addition to being a central signaling kinase in cell survival, AKT1 plays important roles in the nervous system including neuroplasticity and this study examined the localization of exogenous AKT1 in CAD cells. Neuropeptides modulate many signal transduction pathways and melacortins are implicated in regulating growth factor signal transduction pathways, including the PI3K/AKT pathway. AKT1-DsReD was transfected into CAD cells that were stably expressing melanocortin 3-receptor-GFP (MC3R-GFP), a G-protein coupled receptor. The cells were imaged with confocal microscopy to determine the fluorescent protein localization patterns. AKT1-DsRed was predominantly localized in the cytoplasm and the nucleus. Further, expression of exogenous AKT1 in these cell lines led to morphological changes reminiscent of apoptosis. As expected, MC3R-GFP localized to the plasma membrane but it internalized upon cell stimulation with the cognate ligand. In limited areas of the plasma membrane, AKT1-DsRed and MC3R-GFP were colocalized. In conclusion, quantitative studies to understand the role of relative levels of AKT1 in determining cell survival are needed.

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