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Zeitschriftenartikel zum Thema "Autophagic bodies"
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Stefaniak, Szymon, Łukasz Wojtyla, Małgorzata Pietrowska-Borek und Sławomir Borek. „Completing Autophagy: Formation and Degradation of the Autophagic Body and Metabolite Salvage in Plants“. International Journal of Molecular Sciences 21, Nr. 6 (23.03.2020): 2205. http://dx.doi.org/10.3390/ijms21062205.
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Autophagy is an evolutionarily conserved process that occurs in yeast, plants, and animals. Despite many years of research, some aspects of autophagy are still not fully explained. This mostly concerns the final stages of autophagy, which have not received as much interest from the scientific community as the initial stages of this process. The final stages of autophagy that we take into consideration in this review include the formation and degradation of the autophagic bodies as well as the efflux of metabolites from the vacuole to the cytoplasm. The autophagic bodies are formed through the fusion of an autophagosome and vacuole during macroautophagy and by vacuolar membrane invagination or protrusion during microautophagy. Then they are rapidly degraded by vacuolar lytic enzymes, and products of the degradation are reused. In this paper, we summarize the available information on the trafficking of the autophagosome towards the vacuole, the fusion of the autophagosome with the vacuole, the formation and decomposition of autophagic bodies inside the vacuole, and the efflux of metabolites to the cytoplasm. Special attention is given to the formation and degradation of autophagic bodies and metabolite salvage in plant cells.
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Hariri, Mehrdad, Ghania Millane, Marie-Pierre Guimond, Ginette Guay, James W. Dennis und Ivan R. Nabi. „Biogenesis of Multilamellar Bodies via Autophagy“. Molecular Biology of the Cell 11, Nr. 1 (Januar 2000): 255–68. http://dx.doi.org/10.1091/mbc.11.1.255.
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Transfection of Mv1Lu mink lung type II alveolar cells with β1–6-N-acetylglucosaminyl transferase V is associated with the expression of large lysosomal vacuoles, which are immunofluorescently labeled for the lysosomal glycoprotein lysosomal-associated membrane protein-2 and the β1–6-branchedN-glycan-specific lectin phaseolis vulgaris leucoagglutinin. By electron microscopy, the vacuoles present the morphology of multilamellar bodies (MLBs). Treatment of the cells with the lysosomal protease inhibitor leupeptin results in the progressive transformation of the MLBs into electron-dense autophagic vacuoles and eventual disappearance of MLBs after 4 d of treatment. Heterologous structures containing both membrane lamellae and peripheral electron-dense regions appear 15 h after leupeptin addition and are indicative of ongoing lysosome–MLB fusion. Leupeptin washout is associated with the formation after 24 and 48 h of single or multiple foci of lamellae within the autophagic vacuoles, which give rise to MLBs after 72 h. Treatment with 3-methyladenine, an inhibitor of autophagic sequestration, results in the significantly reduced expression of multilamellar bodies and the accumulation of inclusion bodies resembling nascent or immature autophagic vacuoles. Scrape-loaded cytoplasmic FITC-dextran is incorporated into lysosomal-associated membrane protein-2–positive MLBs, and this process is inhibited by 3-methyladenine, demonstrating that active autophagy is involved in MLB formation. Our results indicate that selective resistance to lysosomal degradation within the autophagic vacuole results in the formation of a microenvironment propicious for the formation of membrane lamella.
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Bjørkøy, Geir, Trond Lamark, Andreas Brech, Heidi Outzen, Maria Perander, Aud Øvervatn, Harald Stenmark und Terje Johansen. „p62/SQSTM1 forms protein aggregates degraded by autophagy and has a protective effect on huntingtin-induced cell death“. Journal of Cell Biology 171, Nr. 4 (14.11.2005): 603–14. http://dx.doi.org/10.1083/jcb.200507002.
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Autophagic degradation of ubiquitinated protein aggregates is important for cell survival, but it is not known how the autophagic machinery recognizes such aggregates. In this study, we report that polymerization of the polyubiquitin-binding protein p62/SQSTM1 yields protein bodies that either reside free in the cytosol and nucleus or occur within autophagosomes and lysosomal structures. Inhibition of autophagy led to an increase in the size and number of p62 bodies and p62 protein levels. The autophagic marker light chain 3 (LC3) colocalized with p62 bodies and coimmunoprecipitated with p62, suggesting that these two proteins participate in the same complexes. The depletion of p62 inhibited recruitment of LC3 to autophagosomes under starvation conditions. Strikingly, p62 and LC3 formed a shell surrounding aggregates of mutant huntingtin. Reduction of p62 protein levels or interference with p62 function significantly increased cell death that was induced by the expression of mutant huntingtin. We suggest that p62 may, via LC3, be involved in linking polyubiquitinated protein aggregates to the autophagy machinery.
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Wleklik, Karolina, Szymon Stefaniak, Katarzyna Nuc, Małgorzata Pietrowska-Borek und Sławomir Borek. „Identification and Potential Participation of Lipases in Autophagic Body Degradation in Embryonic Axes of Lupin (Lupinus spp.) Germinating Seeds“. International Journal of Molecular Sciences 25, Nr. 1 (20.12.2023): 90. http://dx.doi.org/10.3390/ijms25010090.
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Autophagy is a fundamental process for plants that plays a crucial role in maintaining cellular homeostasis and promoting survival in response to various environmental stresses. One of the lesser-known stages of plant autophagy is the degradation of autophagic bodies in vacuoles. To this day, no plant vacuolar enzyme has been confirmed to be involved in this process. On the other hand, several enzymes have been described in yeast (Saccharomyces cerevisiae), including Atg15, that possess lipolytic activity. In this preliminary study, which was conducted on isolated embryonic axes of the white lupin (Lupinus albus L.) and Andean lupin (Lupinus mutabilis Sweet), the potential involvement of plant vacuolar lipases in the degradation of autophagic bodies was investigated. We identified in transcriptomes (using next-generation sequencing (NGS)) of white and Andean lupin embryonic axes 38 lipases with predicted vacuolar localization, and for three of them, similarities in amino acid sequences with yeast Atg15 were found. A comparative transcriptome analysis of lupin isolated embryonic axes cultured in vitro under different sucrose and asparagine nutrition, evaluating the relations in the levels of the transcripts of lipase genes, was also carried out. A clear decrease in lipase gene transcript levels caused by asparagine, a key amino acid in lupin seed metabolism which retards the degradation of autophagic bodies during sugar-starvation-induced autophagy in lupin embryonic axes, was detected. Although the question of whether lipases are involved in the degradation of autophagic bodies during plant autophagy is still open, our findings strongly support such a hypothesis.
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Takeshige, K., M. Baba, S. Tsuboi, T. Noda und Y. Ohsumi. „Autophagy in yeast demonstrated with proteinase-deficient mutants and conditions for its induction.“ Journal of Cell Biology 119, Nr. 2 (15.10.1992): 301–11. http://dx.doi.org/10.1083/jcb.119.2.301.
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For determination of the physiological role and mechanism of vacuolar proteolysis in the yeast Saccharomyces cerevisiae, mutant cells lacking proteinase A, B, and carboxypeptidase Y were transferred from a nutrient medium to a synthetic medium devoid of various nutrients and morphological changes of their vacuoles were investigated. After incubation for 1 h in nutrient-deficient media, a few spherical bodies appeared in the vacuoles and moved actively by Brownian movement. These bodies gradually increased in number and after 3 h they filled the vacuoles almost completely. During their accumulation, the volume of the vacuolar compartment also increased. Electron microscopic examination showed that these bodies were surrounded by a unit membrane which appeared thinner than any other intracellular membrane. The contents of the bodies were morphologically indistinguishable from the cytosol; these bodies contained cytoplasmic ribosomes, RER, mitochondria, lipid granules and glycogen granules, and the density of the cytoplasmic ribosomes in the bodies was almost the same as that of ribosomes in the cytosol. The diameter of the bodies ranged from 400 to 900 nm. Vacuoles that had accumulated these bodies were prepared by a modification of the method of Ohsumi and Anraku (Ohsumi, Y., and Y. Anraku. 1981. J. Biol. Chem. 256:2079-2082). The isolated vacuoles contained ribosomes and showed latent activity of the cytosolic enzyme glucose-6-phosphate dehydrogenase. These results suggest that these bodies sequestered the cytosol in the vacuoles. We named these spherical bodies "autophagic bodies." Accumulation of autophagic bodies in the vacuoles was induced not only by nitrogen starvation, but also by depletion of nutrients such as carbon and single amino acids that caused cessation of the cell cycle. Genetic analysis revealed that the accumulation of autophagic bodies in the vacuoles was the result of lack of the PRB1 product proteinase B, and disruption of the PRB1 gene confirmed this result. In the presence of PMSF, wild-type cells accumulated autophagic bodies in the vacuoles under nutrient-deficient conditions in the same manner as did multiple protease-deficient mutants or cells with a disrupted PRB1 gene. As the autophagic bodies disappeared rapidly after removal of PMSF from cultures of normal cells, they must be an intermediate in the normal autophagic process. This is the first report that nutrient-deficient conditions induce extensive autophagic degradation of cytosolic components in the vacuoles of yeast cells.
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Yang, Zhifen, Ju Huang, Jiefei Geng, Usha Nair und Daniel J. Klionsky. „Atg22 Recycles Amino Acids to Link the Degradative and Recycling Functions of Autophagy“. Molecular Biology of the Cell 17, Nr. 12 (Dezember 2006): 5094–104. http://dx.doi.org/10.1091/mbc.e06-06-0479.
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In response to stress conditions (such as nutrient limitation or accumulation of damaged organelles) and certain pathological situations, eukaryotic cells use autophagy as a survival mechanism. During nutrient stress the main purpose of autophagy is to degrade cytoplasmic materials within the lysosome/vacuole lumen and generate an internal nutrient pool that is recycled back to the cytosol. This study elucidates a molecular mechanism for linking the degradative and recycling roles of autophagy. We show that in contrast to published studies, Atg22 is not directly required for the breakdown of autophagic bodies within the lysosome/vacuole. Instead, we demonstrate that Atg22, Avt3, and Avt4 are partially redundant vacuolar effluxers, which mediate the efflux of leucine and other amino acids resulting from autophagic degradation. The release of autophagic amino acids allows the maintenance of protein synthesis and viability during nitrogen starvation. We propose a “recycling” model that includes the efflux of macromolecules from the lysosome/vacuole as the final step of autophagy.
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Baba, M., K. Takeshige, N. Baba und Y. Ohsumi. „Ultrastructural analysis of the autophagic process in yeast: detection of autophagosomes and their characterization“. Journal of Cell Biology 124, Nr. 6 (15.03.1994): 903–13. http://dx.doi.org/10.1083/jcb.124.6.903.
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Under nutrient-deficient conditions, the yeast S. cerevisiae sequesters its own cytoplasmic components into vacuoles in the form of "autophagic bodies" (Takeshige, K., M. Baba, S. Tsuboi, T. Noda, and Y. Ohsumi. 1992. J. Cell Biol. 119:301-311). Immunoelectron microscopy showed that two cytosolic marker enzymes, alcohol dehydrogenase and phosphoglycerate kinase, are present in the autophagic bodies at the same densities as in the cytosol, but are not present in vacuolar sap, suggesting that cytosolic enzymes are also taken up into the autophagic bodies. To understand this process, we performed morphological analyses by transmission and immunological electron microscopies using a freeze-substitution fixation method. Spherical structures completely enclosed in a double membrane were found near the vacuoles of protease-deficient mutant cells when the cells were shifted to nutrient-starvation media. Their size, membrane thickness, and contents of double membrane-structures corresponded well with those of autophagic bodies. Sometimes these double membrane structures were found to be in contact with the vacuolar membrane. Furthermore their outer membrane was occasionally seen to be continuous with the vacuolar membrane. Histochemical staining of carbohydrate strongly suggested that the structures with double membranes fused with the vacuoles. These results indicated that these structures are precursors of autophagic bodies, "autophagosomes" in yeast. All the data obtained suggested that the autophagic process in yeast is essentially similar to that of the lysosomal system in mammalian cells.
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Epple, Ulrike D., Ivet Suriapranata, Eeva-Liisa Eskelinen und Michael Thumm. „Aut5/Cvt17p, a Putative Lipase Essential for Disintegration of Autophagic Bodies inside the Vacuole“. Journal of Bacteriology 183, Nr. 20 (15.10.2001): 5942–55. http://dx.doi.org/10.1128/jb.183.20.5942-5955.2001.
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ABSTRACT Selective disintegration of membrane-enclosed autophagic bodies is a feature of eukaryotic cells not studied in detail. Using aSaccharomyces cerevisiae mutant defective in autophagic-body breakdown, we identified and characterized Aut5p, a glycosylated integral membrane protein. Site-directed mutagenesis demonstrated the relevance of its putative lipase active-site motif for autophagic-body breakdown. aut5Δ cells show reduced protein turnover during starvation and are defective in maturation of proaminopeptidase I. Most recently, by means of the latter phenotype, Aut5p was independently identified as Cvt17p. In this study we additionally checked for effects on vacuolar acidification and detected mature vacuolar proteases, both of which are prerequisites for autophagic-body lysis. Furthermore, biologically active hemagglutinin-tagged Aut5p (Aut5-Ha) localizes to the endoplasmic reticulum (nuclear envelope) and is targeted to the vacuolar lumen independent of autophagy. In pep4Δ cells immunogold electron microscopy located Aut5-Ha at ∼50-nm-diameter intravacuolar vesicles. Characteristic missorting in vps class E and fab1Δ cells, which affects the multivesicular body (MVB) pathway, suggests vacuolar targeting of Aut5-Ha similar to that of the MVB pathway. In agreement with localization of Aut5-Ha at intravacuolar vesicles inpep4Δ cells and the lack of vacuolar Aut5-Ha in wild-type cells, our pulse-chase experiments clearly indicated that Aut5-Ha degradation with 50 to 70 min of half-life is dependent on vacuolar proteinase A.
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Li, Qingrong, Xiaojuan Deng, Wanying Yang, Zhijun Huang, Gianluca Tettamanti, Yang Cao und Qili Feng. „Autophagy, apoptosis, and ecdysis-related gene expression in the silk gland of the silkworm (Bombyx mori) during metamorphosis“. Canadian Journal of Zoology 88, Nr. 12 (Dezember 2010): 1169–78. http://dx.doi.org/10.1139/z10-083.
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Degeneration of larval-specific tissues during insect metamorphosis has been suggested to be the result of apoptosis and autophagy and is triggered by ecdysteroids. However, the relationship between autophagy and apoptosis pathways and the mechanism of regulation by ecdysteroids remain to be elucidated. This study examined the events of autophagy, apoptosis, and the expression of ecdysis-related genes in the silk gland of the silkworm ( Bombyx mori L., 1758) during the larval to pupal transformation. The results indicated that autophagic features appeared in the silk gland at the wandering and spinning stages of the larvae, whereas the apoptotic features such as apoptotic bodies and DNA fragmentation occurred at the prepupal or early-pupal stages. The autophagic granules fused with each other to form large vacuoles where the cytoplasmic material was degraded. Autophagosomes, autolysosomes, and apoptotic bodies were found later in the degenerating silk-gland cells. Expression of the ecdysone receptor gene BmEcR and the transcription factor genes BmE74A and BmBR-C preceded the onset of autophagy and apoptosis, indicating that they may be responsible for triggering these programmed cell death pathways in the silk gland. The results suggest that both autophagy and apoptosis occur in the silk-gland cells during degeneration, but autophagy precedes apoptosis.
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Dernovics, Áron, György Seprényi, Zsolt Rázga, Ferhan Ayaydin, Zoltán Veréb und Klára Megyeri. „Phenol-Soluble Modulin α3 Stimulates Autophagy in HaCaT Keratinocytes“. Biomedicines 11, Nr. 11 (10.11.2023): 3018. http://dx.doi.org/10.3390/biomedicines11113018.
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Background: Phenol-soluble modulins (PSMs) are pore-forming toxins (PFTs) produced by staphylococci. PSMs exert diverse cellular effects, including lytic, pro-apoptotic, pro-inflammatory and antimicrobial actions. Since the effects of PSMs on autophagy have not yet been reported, we evaluated the autophagic activity in HaCaT keratinocytes treated with recombinant PSMα3. Methods: The autophagic flux and levels of autophagic marker proteins were determined using Western blot analysis. Subcellular localization of LC3B and Beclin-1 was investigated using an indirect immunofluorescence assay. The ultrastructural features of control and PSMα3-treated cells were evaluated via transmission electron microscopy. Cytoplasmic acidification was measured via acridine orange staining. Phosphorylation levels of protein kinases, implicated in autophagy regulation, were studied using a phospho-kinase array and Western blot analysis. Results: PSMα3 facilitated the intracellular redistribution of LC3B, increased the average number of autophagosomes per cell, promoted the development of acidic vesicular organelles, elevated the levels of LC3B-II, stimulated autophagic flux and triggered a significant decrease in the net autophagic turnover rate. PSMα3 induced the accumulation of autophagosomes/autolysosomes, amphisomes and multilamellar bodies at the 0.5, 6 and 24 h time points, respectively. The phospho-Akt1/2/3 (T308 and S473), and phospho-mTOR (S2448) levels were decreased, whereas the phospho-Erk1/2 (T202/Y204 and T185/Y187) level was increased in PSMα3-treated cells. Conclusions: In HaCaT keratinocytes, PSMα3 stimulates autophagy. The increased autophagic activity elicited by sub-lytic PSM concentrations might be an integral part of the cellular defense mechanisms protecting skin homeostasis.
Dissertationen zum Thema "Autophagic bodies"
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Castets, Julie. „Caractérisation fonctionnelle d’une protéine à L’intersection entre le métabolisme des lipides et L’autophagie chez arabidopsis“. Electronic Thesis or Diss., Bordeaux, 2024. https://theses.hal.science/tel-05000653.
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L'autophagie est un processus de dégradation intracellulaire universellement conservé chezl’ensemble des eucaryotes et essentiel au développement et à la physiologie des plantes. L'autophagie repose sur la formation de vésicules membranaires spécialisées, les autophagosomes, qui séquestrent et acheminent le cargo autophagique jusqu'à la vacuole lytique. Après la fusion avec le tonoplaste, les corps autophagiques sont libérés dans le lumen vacuolaire et rapidement hydrolysés pour garantir la dégradation de leur cargo. Comment les vacuoles gèrent l’influx de corps autophagiques lors de l'induction de l'autophagie et la manière dont la membrane du corps autophagique est spécifiquement hydrolysée restent totalement inconnues. En amont de ce projet, l'immuno-isolation de compartiments autophagiques a permis d'identifier une phospholipase atypique, LCAT4, comme composant putatif de la machinerie d'autophagie. L'étude de la localisation subcellulaire de LCAT4 a révélé son association avec les compartiments précoces, et tardifs, de l'autophagie, y compris les corps autophagiques. En condition de carence en nutriment, LCAT4 est massivement relocalisée à l'intérieur du lumen vacuolaire et ce transport est médié par la voie de l'autophagie ce qui suggère que cette enzyme, active à pH acide, pourrait être impliquée dans la dégradation de la membrane autophagique et/ou du cargo dans la vacuole. La génération et la caractérisation de plantes knock-out ou knockdown pour LCAT4 montre que l’absence de ce gène ne provoque pas de défauts d’un point de vue physiologique ou au niveau du flux autophagique, ce qui suggère que l'activité de LCAT4 pourrait être compensée par d'autres phospholipases. Nos résultats ont montré qu’en effet, LCAT3, l'homologue le plus proche de LCAT4, colocalise également avec les corps autophagiques en l’absence de nutriments. Alors que les mutants knock-out pour LCAT3 ne présentent pas de phénotype différent des plantes sauvages, nos analyses par microscopie à fluorescence et microscopie électronique du double mutant knock-out lcat4 lcat3 suggère une accumulation de corps autophagiques en condition de carence, qui est corrélée à un ralentissement significatif du flux autophagique. En conclusion, nos travaux permettent de caractériser de nouveaux acteurs de la machinerie d'autophagie et de mettre en lumière l'avant-dernière étape de ce processus critique pour la tolérance des plantes aux stress environnementauxAutophagy is an intracellular degradation process conserved across eukaryotes and critical for plant development and physiology. Autophagy relies on the formation of specialized membrane vesicles, called autophagosome, that encapsulate and traffic cargo to the lytic vacuole. Upon fusion with the tonoplast, autophagic bodies are released inside the vacuolar lumen and rapidly hydrolyzed to guarantee cargo degradation. How plant vacuoles deal with the large influx of autophagic bodies upon autophagy induction and how the membrane of the autophagic body is specifically hydrolyzed remain completely unknown. Upstream of this project, immuno-isolation of autophagy compartments identified an atypical phospholipase, LCAT4, as a putative component of the autophagy machinery. Studying the subcellular localization of LCAT4 revealed its associatation with early and late autophagy compartments, including autophagic bodies. Upon starvation, LCAT4 massively relocates inside the vacuole lumen using autophagy as a transport system, suggesting that LCAT4 could be involved in the disruption of autophagic membrane and/or cargo in the vacuole. Seedlings knocked-out for LCAT4 do not show defects in physiology or autophagic flux, suggesting that the activity of LCAT4 could be compensated by additional phospholipases. Indeed, LCAT3, the closest homolog of LCAT4 co-localizes with autophagic bodies under starvation. Fluorescent and electronic microscopy analyses demonstrate an accumulation of autophagic bodies inside the vacuole in the double lcat3 lcat4 knock out mutant and this is correlated with a significant slowdown in the autophagic flux. Together, this work characterizes novel actors of the autophagy machinery thus shading light on the penultimate step of this critical process for plant tolerance to environmental stresses
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Shah, Khyati H. „REGULATION, COMPOSITION AND FUNCTIONS OF RNP GRANULES IN QUIESCENT CELLS OF SACCHAROMYCES CEREVISIAE“. The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417541239.
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Lajoie, Patrick. „Regulation of receptor signaling and membrane trafficking by beta1,6-branched n-glycans and caveolin-1/cholesterol membrane domain organization“. Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/336.
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Modification by glycosylation gives proteins a range of diverse functions reflecting their structural variability. N-glycans regulate many biological outcomes in mammalian cells under both normal and pathological conditions. They play a major role in various pathologies such as cancer and lysosomal storage diseases. Interplay between N-glycans and other regulators, such as membrane lipid domains, in the control of signaling pathways remains poorly understood. My thesis therefore focuses on how N-glycans and membrane lipid domains oppose and/or work together at different cellular levels to regulate various processes such as receptor signaling and diffusion, endocytosis and lysosomal organelle biogenesis.
Mgat5 encodes for ß1,6-N-acetylglucosaminyltransferase V that produces N-glycans, the preferred ligand for galectins. In tumor cells, galectins bind glycosylated receptors at the cell surface forming a lattice, that restricts receptor endocytosis and enhances its residency at the plasma membrane. In the first part of my thesis, I report that Galectin/receptor crosslinking opposes receptor sequestration by oligomerized caveolin-1 (Cav1) domains overriding its negative regulation of epidermal growth factor receptor (EGFR) signaling, cell surface diffusion and tumor growth. These results identify Cav1 as a conditional tumor suppressor.
I also demonstrate that Cav1 is a negative regulator of lipid raft-mediated endocytosis. Cav1 indirectly regulates the internalization of cholera toxin b subunit to the Golgi apparatus independently of caveolae formation. That identifies a new role for caveolin-1 outside caveolae in the regulation of raft-dependent endocytosis
Finally, Mgat5 overexpression in pneumocytes is associated with the expression of a lysosomal organelle, the multilamellar body (MLB), via autophagy. MLB expression is also a characteristic of various lysosomal storage diseases. I demonstrate that cholesterol accumulation can override the need for Mgat5 overexpression in MLB formation indicating that they may form via multiple mechanisms. However, I also demonstrate that a contribution of the autophagic pathway is a common determinant of biogenesis of MLB of various lipid compositions.
In conclusion, Mgat5-dependent protein glycosylation and Cav1/raft domains therefore both function as regulators of plasma membrane interactions, endocytosis and lysosomal organelle biogenesis. Understanding of this interplay is crucial for the understanding of the mechanisms involve in various pathologies such as cancer and lysosomal storage diseases.
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Vanderperre, Solène. „Analyse d'interactions Hox/Cofacteur à l'échelle super-résolutive et contrôle transcriptionnel de l'autophagie chez la drosophile“. Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEN048.
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La régulation transcriptionnelle est le sujet principal de nombreuses recherches et est un mécanisme indispensable pour assurer les fonctions cellulaires de tout organisme. Les avancées technologiques dans le monde de la microscopie ouvrent de nouvelles opportunités pour visualiser différentes étapes de ce mécanisme. Notamment les dynamiques et la localisation d’un FT a l’échelle super-résolutive. Cependant, un unique FT n’est pas suffisant pour réguler finement l’activation ou la répression de la transcription d’un gène. En effet, différents complexes de FT coopèrent pour atteindre une telle précision de régulation. La visualisation de la fixation d’un complexe (binaire) sur sa séquence régulatrice cible serait donc un atout pour mieux déchiffrer la régulation transcription elle.La première partie de mon travail de Thèse a consisté à mettre en place des outils permettant de visualiser en microscopie confocale et super-résolution, la fixation de complexes Hox-cofacteur sur des séquences ADN cibles spécifiques. Ces outils ont été appliques pour quantifier l’enrichissement de différents complexes Hox/Exd au niveau d’un enhancer connu (appelé fkh250) du gène cible forkhead (fkh) dans les glandes salivaires de la larve de drosophile. J’ai combine la méthode de BiFC (confocale) ou BiFC-PALM (super-résolution) et le système ParB/INT pour visualiser simultanément les complexes Hox/Exd et l’enhancer fkh250, respectivement.Mes analyses confirment un enrichissement spécifique des complexes Hox/Exd sur les différents types d’enhancer fkh250. Surtout, des résultats préliminaires indiquent la possibilité de quantifier le nombre exact de complexes Hox/Exd fixes sur l’enhancer fkh250 a l’échelle super-résolutive.La deuxième partie de mon travail de thèse concerne l’analyse d’une nouvelle interaction entre les protéines Hox avec la Lamine C (LamC) pour une répression transcriptionnelle active des gènes lies a l’autophagie (atg) dans le corps gras de la larve de drosophile. Ce travail a permis de révéler un profil de co-expression typique des protéines Hox et de la LamC, au sein du noyau par imagerie confocale ≪ Lightning ≫ et l’importance de contrôler le positionnement des loci génomiques pour une régulation fine de la transcriptionTranscriptional regulation is essential for all cellular functions and is the subject of a number of studies. Technological advances in the field of microscopy open new opportunities to visualize different steps of this mechanism. In particular, it allows visualizing individual TFs at the super resolution scale in vivo.However, an isolated TF is not sufficient to tightly regulate the activation or repression of a target gene. Indeed, different complexes need to cooperate to achieve this level of accurate control. The observation of binary protein-protein interactions bound on a specific DNA sequence would be an asset to decipher the complex mechanism of transcription.The first part of my thesis project consisted to establish the tools allowing the visualization of different Hox-cofactor complexes on a specific target sequence, at confocal resolution and super-resolution. These tools were applied to quantify a specific enrichment of Hox/Exd complexes on a well characterized enhancer called fkh250. This enhancer is regulating the expression of a Drosophila salivary gland gene named forkhead (fkh). I combined Bimolecular Fluorescent Complementation (BiFC) (confocal resolution) or BiFC-PALM (super-resolution) with the ParB/INT system to simultaneously detect Hox/Exd complexes bound to the fkh250 enhancer,respectively.My results confirm a specific enrichment of Hox/Exd complexes on several fkh250 enhancers. Moreover, my preliminary results show the possibility to perform bi-colour PALM for revealing in the same nucleus the Hox/Exd complexes and its target DNA sequences.The second part of my project revealed a new interaction between Hox proteins and a nuclear matrix component, the Lamin C (LamC), in the context of transcriptional repression of autophagy related genes (atg) in Drosophila larval fat body. This work revealed a typical profile of co-expression of Hox and LamC in Drosophila fat body nuclei. This profile was imaged through confocal Lightning microscopy. These results also revealed the importance of genomic loci positionning for the fine control of transcription
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Su, Yu-Cheng, und 蘇育正. „Eburicoic acid, an active triterpenoid from the fruiting bodies of basswood cultivated Antrodia cinnamomea, induces ER stress-mediated autophagy in human hepatoma cells“. Thesis, 2012. http://ndltd.ncl.edu.tw/handle/85067814339771723291.
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碩士國立臺灣大學
食品科技研究所
100
Liver cancer is the second leading cause of cancer deaths in Taiwan as per the 2011 statistics, and ranks the fourth in cancer related mortality in the world. Hence to maintain a healthy liver is a big issue in Taiwan. Recent researches have shown that Antrodia cinnamomea, a Taiwan-specific medicinal mushroom, can manipulate biological activities, including hepatoprotection, anti-inflammation, anti-HBV activity, anticancer activity, etc. The active constituents include polysaccharides, benzenoids, triterpenoids, steroids, etc., and among them triterpenoids are the most prominent because of their potent anticancer effects. In this study, the anti-liver cancer activity and molecular mechanisms of eburicoic acid, the second most abundant triterpenoid from the fruiting bodies of basswood cultivated Antrodia cinnamomea was investigated using the human hepatoma Hep 3B cells. The results show that eburicoic acid effectively reduced Hep 3B cell viability within 24 hours, and the IC50 was 18.4 μM, which was equivalent to 8.7 μg/mL. Besides, eburicoic acid induced conversion of LC3-Ⅰto LC3-Ⅱ and a large number of autophagosomes/autophagolysosomes formation, but increasing of hypodiploid proportion or cell lysis obviously in Hep 3B cells. So the principal mode of Hep 3B cell death induced by eburicoic acid was autophagy, rather than apoptosis or necrosis. In depth investigation for the molecular mechanisms, revealed that eburicoic acid firstly promoted ROS generation and ATP depletion, leading to ER stress, followed by elevated cytosolic calcium ion concentration and BiP expression, downregulated phosphorylation of DAPK, upregulated phosphorylation of Beclin-1, JNK, and Bcl-2, and finally induced autophagy in Hep 3B cells. These results indicate that eburicoic acid has significant anti-liver cancer effects and more distinctive mechanisms. Coupled with these findings and the high content of eburicoic acid in the fruiting bodies of basswood cultivated Antrodia cinnamomea, eburicoic acid has the potential for mass production and to assist cancer therapy.
Bücher zum Thema "Autophagic bodies"
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Pilon, Rachel, und Naomi William. Secrets of Autophagy: The Powerful Healing of Autophagy Uses Your Bodies Natural Intelligence to Promote Anti Ageing . Learn How to Initiate It Through Extended Water, Intermittent Fasting and More. Independently Published, 2018.
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1
Waguri, Satoshi, und Masaaki Komatsu. „Chapter 9 Biochemical and Morphological Detection of Inclusion Bodies in Autophagy‐Deficient Mice“. In Autophagy in Disease and Clinical Applications, Part C, 181–96. Elsevier, 2009. http://dx.doi.org/10.1016/s0076-6879(08)04009-3.
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2
Ahmad Joyia, Faiz, Ghulam Mustafa und Muhammad Sarwar Khan. „Chloroplast Recycling and Plant Stress Tolerance“. In Physiology. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.114852.
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Plastids have emerged as pivotal regulators of plant’s response to biotic and abiotic stresses. Chloroplasts have the ability to synthesize a variety of pigments, secondary metabolites, and phytohormones which help plant cells to withstand adverse conditions. Further, plastids communicate with the nucleus and other cellular organelles for the acquisition of essential molecules to survive under unfavorable conditions. They act as environmental sensors which not only synthesize molecules for stress tolerance but also induce nucleus-encoded genes for stress resilience. Senescence is a key developmental process in this context and plays an important role in the release of essential nutrients. Chloroplast proteolytic machinery plays a crucial role in the degradation or remodeling of plastid proteins resulting in the generation of numerous endogenous peptides which are present in the plant secretome. Plastid chaperone system is also activated for the repair/refold of damaged proteins resulting in improved tolerance to stresses. Autophagy is a conserved process that involves large-scale breakdown of chloroplast through piecemeal degradation and chlorophagy. The piecemeal degradation occurs through Rubisco-containing bodies (RCBs) and senescence-associated vacuoles (SAVs), whereas chlorophagy targets chloroplasts as a whole. Though information about chloroplast recycling is limited, the present work provides a comprehensive review on chloroplast recycling and its role in stress mitigation and adaptation in climate change scenarios.