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Item does not contain fulltext, Endosomal Sorting Complex Required for Transport (ESCRT) proteins can be transiently recruited to the plasma membrane for membrane repair and formation of extracellular vesicles. Here, we discovered micrometer-sized worm-shaped ESCRT structures that stably persist for multiple hours at the plasma membrane of macrophages, dendritic cells, and fibroblasts. These structures surround clusters of integrins and known cargoes of extracellular vesicles. The ESCRT structures are tightly connected to the cellular support and are left behind by the cells together with surrounding patches of membrane. The phospholipid composition is altered at the position of the ESCRT structures, and the actin cytoskeleton is locally degraded, which are hallmarks of membrane damage and extracellular vesicle formation. Disruption of actin polymerization increased the formation of the ESCRT structures and cell adhesion. The ESCRT structures were also present at plasma membrane contact sites with membrane-disrupting silica crystals. We propose that the ESCRT proteins are recruited to adhesion-induced membrane tears to induce extracellular shedding of the damaged membrane.

Item does not contain fulltext

Item does not contain fulltext, Catestatin (CST) is a bioactive cleavage product of the neuroendocrine prohormone chromogranin A (CgA). Recent findings show that CST can exert anti-inflammatory and antiadrenergic effects by suppressing the inflammatory actions of mammalian macrophages. However, recent findings also suggest that macrophages themselves are major CST producers. Here, we hypothesize that macrophages produce CST in an inflammation-dependent manner and thereby might self-regulate inflammation in an autocrine fashion. CST is associated with pathological conditions hallmarked by chronic inflammation, including autoimmune, cardiovascular, and metabolic disorders. Since intraperitoneal injection of CST in mouse models of diabetes and inflammatory bowel disease has been reported to be beneficial for mitigating disease, we posit that CST should be further investigated as a candidate target for treating certain inflammatory diseases.

Contains fulltext : 247928.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 252559.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 247928.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 252559.pdf (Publisher’s version ) (Open Access)

Item does not contain fulltext, Catestatin (CST) is a bioactive cleavage product of the neuroendocrine prohormone chromogranin A (CgA). Recent findings show that CST can exert anti-inflammatory and antiadrenergic effects by suppressing the inflammatory actions of mammalian macrophages. However, recent findings also suggest that macrophages themselves are major CST producers. Here, we hypothesize that macrophages produce CST in an inflammation-dependent manner and thereby might self-regulate inflammation in an autocrine fashion. CST is associated with pathological conditions hallmarked by chronic inflammation, including autoimmune, cardiovascular, and metabolic disorders. Since intraperitoneal injection of CST in mouse models of diabetes and inflammatory bowel disease has been reported to be beneficial for mitigating disease, we posit that CST should be further investigated as a candidate target for treating certain inflammatory diseases.

Contains fulltext : 244568.pdf (Publisher’s version ) (Closed access), AIM: A 'leaky' gut barrier has been implicated in the initiation and progression of a multitude of diseases, e.g., inflammatory bowel disease (IBD), irritable bowel syndrome, and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier. METHODS: Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analyzed by immunohistochemistry, Western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients. RESULTS: Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (i) elongated tight, adherens junctions and desmosomes similar to IBD patients, (ii) elevated expression of Claudin 2, and (iii) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-knockout mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-knockout mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-knockout mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability. CONCLUSION: The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

Contains fulltext : 239969.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 234167.pdf (Publisher’s version ) (Open Access)

Radboud University, 01 oktober 2021, Promotores : Bogaart, G. van den, Lefeber, D.J. Co-promotor : Beest, M.B.A. ter, Contains fulltext : 236659.pdf (Publisher’s version ) (Open Access)

Item does not contain fulltext

Radboud University, 11 oktober 2021, Promotores : Figdor, C.G., Bogaart, G. van den Co-promotores : Christoffersson, G., Mahata, S., Contains fulltext : 236684.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 230383.pdf (publisher's version ) (Open Access)

Contains fulltext : 234167.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 244568.pdf (Publisher’s version ) (Closed access), AIM: A 'leaky' gut barrier has been implicated in the initiation and progression of a multitude of diseases, e.g., inflammatory bowel disease (IBD), irritable bowel syndrome, and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier. METHODS: Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analyzed by immunohistochemistry, Western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients. RESULTS: Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (i) elongated tight, adherens junctions and desmosomes similar to IBD patients, (ii) elevated expression of Claudin 2, and (iii) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-knockout mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-knockout mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-knockout mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability. CONCLUSION: The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

Radboud University, 01 oktober 2021, Promotores : Bogaart, G. van den, Lefeber, D.J. Co-promotor : Beest, M.B.A. ter, Contains fulltext : 236659.pdf (Publisher’s version ) (Open Access)

Radboud University, 11 oktober 2021, Promotores : Figdor, C.G., Bogaart, G. van den Co-promotores : Christoffersson, G., Mahata, S., Contains fulltext : 236684.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 233551.pdf (Publisher’s version ) (Closed access)

Contains fulltext : 239969.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 230383.pdf (publisher's version ) (Open Access)

Contains fulltext : 230383.pdf (publisher's version ) (Open Access)

Radboud University, 01 oktober 2021, Promotores : Bogaart, G. van den, Lefeber, D.J. Co-promotor : Beest, M.B.A. ter, Contains fulltext : 236659.pdf (Publisher’s version ) (Open Access)

Radboud University, 11 oktober 2021, Promotores : Figdor, C.G., Bogaart, G. van den Co-promotores : Christoffersson, G., Mahata, S., Contains fulltext : 236684.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 234167.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 244568.pdf (Publisher’s version ) (Closed access), AIM: A 'leaky' gut barrier has been implicated in the initiation and progression of a multitude of diseases, e.g., inflammatory bowel disease (IBD), irritable bowel syndrome, and celiac disease. Here we show how pro-hormone Chromogranin A (CgA), produced by the enteroendocrine cells, and Catestatin (CST: hCgA352-372 ), the most abundant CgA-derived proteolytic peptide, affect the gut barrier. METHODS: Colon tissues from region-specific CST-knockout (CST-KO) mice, CgA-knockout (CgA-KO) and WT mice were analyzed by immunohistochemistry, Western blot, ultrastructural and flowcytometry studies. FITC-dextran assays were used to measure intestinal barrier function. Mice were supplemented with CST or CgA fragment pancreastatin (PST: CgA250-301 ). The microbial composition of cecum was determined. CgA and CST levels were measured in blood of IBD patients. RESULTS: Plasma levels of CST were elevated in IBD patients. CST-KO mice displayed (i) elongated tight, adherens junctions and desmosomes similar to IBD patients, (ii) elevated expression of Claudin 2, and (iii) gut inflammation. Plasma FITC-dextran measurements showed increased intestinal paracellular permeability in the CST-knockout mice. This correlated with a higher ratio of Firmicutes to Bacteroidetes, a dysbiotic pattern commonly encountered in various diseases. Supplementation of CST-knockout mice with recombinant CST restored paracellular permeability and reversed inflammation, whereas CgA-knockout mice supplementation with CST and/or PST in CgA-KO mice showed that intestinal paracellular permeability is regulated by the antagonistic roles of these two peptides: CST reduces and PST increases permeability. CONCLUSION: The pro-hormone CgA regulates the intestinal paracellular permeability. CST is both necessary and sufficient to reduce permeability and primarily acts by antagonizing PST.

Contains fulltext : 229312.pdf (publisher's version ) (Open Access), Major histocompatibility complex (MHC) molecules are well-known for their role in antigen (cross-) presentation, thereby functioning as key players in the communication between immune cells, for example dendritic cells (DCs) and T cells, or immune cells and their targets, such as T cells and virus-infected or tumor cells. However, much less appreciated is the fact that MHC molecules can also act as signaling receptors. In this process, here referred to as reverse MHC class I (MHC-I) signaling, ligation of MHC molecules can lead to signal-transduction and cell regulatory effects in the antigen presenting cell. In the case of MHC-I, reverse signaling can have several outcomes, including apoptosis, migration, induced or reduced proliferation and cytotoxicity towards target cells. Here, we provide an overview of studies showing the signaling pathways and cell outcomes upon MHC-I stimulation in various immune and non-immune cells. Signaling molecules like RAC-alpha serine/threonine-protein kinase (Akt1), extracellular signal-regulated kinases 1/2 (ERK1/2), and nuclear factor-kappaB (NF-kappaB) were common signaling molecules activated upon MHC-I ligation in multiple cell types. For endothelial and smooth muscle cells, the in vivo relevance of reverse MHC-I signaling has been established, namely in the context of adverse effects after tissue transplantation. For other cell types, the role of reverse MHC-I signaling is less clear, since aspects like the in vivo relevance, natural MHC-I ligands and the extended downstream pathways are not fully known.The existing evidence, however, suggests that reverse MHC-I signaling is involved in the regulation of the defense against bacterial and viral infections and against malignancies. Thereby, reverse MHC-I signaling is a potential target for therapies against viral and bacterial infections, cancer immunotherapies and management of organ transplantation outcomes.

Contains fulltext : 229361.pdf (publisher's version ) (Open Access), The contribution of dendritic cell (DC) antigen cross-presentation to the activation of CD8(+) T lymphocytes for immune defense against tumors, viruses, and intracellular pathogens has been recognized widely. Although originally thought to be an exclusive characteristic of DCs, recently also other immune cells, particularly macrophages, have been shown capable of cross-presentation. Here we provide an overview of in vitro and in vivo evidence on cross-presentation by macrophages. As we discuss, it is now firmly established that various types of tissue-resident macrophages are able to cross-present via similar cellular pathways as DCs. This is based on a wide range of antigens in macrophages from many different tissue origins such as blood, tumors, and lymphoid tissue. However, the physiological relevance of macrophage cross-presentation with potential contributions to activation of CD8(+) T lymphocytes is still mostly unknown. While cross-presentation by various types of proinflammatory macrophages might be involved in cross-priming of naive CD8(+) T lymphocytes, it might also be involved in local reactivation of memory and/or effector CD8(+) T lymphocytes. Moreover, cross-presentation by anti-inflammatory macrophages could be related to immune tolerance. Because cross-presentation promotes the initiation and potentiation of antigen-specific CD8(+) T lymphocyte responses, stimulating macrophages to cross-present antigen might be a promising strategy for antitumor or antiviral therapies.

Contains fulltext : 225799.pdf (publisher's version ) (Open Access), Glycosylation is an important post-translational modification for both intracellular and secreted proteins. For glycosylation to occur, cargo must be transported after synthesis through the different compartments of the Golgi apparatus where distinct monosaccharides are sequentially bound and trimmed, resulting in increasingly complex branched glycan structures. Of utmost importance for this process is the intraorganellar environment of the Golgi. Each Golgi compartment has a distinct pH, which is maintained by the vacuolar H(+)-ATPase (V-ATPase). Moreover, tethering factors such as Golgins and the conserved oligomeric Golgi (COG) complex, in concert with coatomer (COPI) and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion, efficiently deliver glycosylation enzymes to the right Golgi compartment. Together, these factors maintain intra-Golgi trafficking of proteins involved in glycosylation and thereby enable proper glycosylation. However, pathogenic mutations in these factors can cause defective glycosylation and lead to diseases with a wide variety of symptoms such as liver dysfunction and skin and bone disorders. Collectively, this group of disorders is known as congenital disorders of glycosylation (CDG). Recent technological advances have enabled the robust identification of novel CDGs related to membrane trafficking components. In this review, we highlight differences and similarities between membrane trafficking-related CDGs.

Contains fulltext : 229312.pdf (publisher's version ) (Open Access), Major histocompatibility complex (MHC) molecules are well-known for their role in antigen (cross-) presentation, thereby functioning as key players in the communication between immune cells, for example dendritic cells (DCs) and T cells, or immune cells and their targets, such as T cells and virus-infected or tumor cells. However, much less appreciated is the fact that MHC molecules can also act as signaling receptors. In this process, here referred to as reverse MHC class I (MHC-I) signaling, ligation of MHC molecules can lead to signal-transduction and cell regulatory effects in the antigen presenting cell. In the case of MHC-I, reverse signaling can have several outcomes, including apoptosis, migration, induced or reduced proliferation and cytotoxicity towards target cells. Here, we provide an overview of studies showing the signaling pathways and cell outcomes upon MHC-I stimulation in various immune and non-immune cells. Signaling molecules like RAC-alpha serine/threonine-protein kinase (Akt1), extracellular signal-regulated kinases 1/2 (ERK1/2), and nuclear factor-kappaB (NF-kappaB) were common signaling molecules activated upon MHC-I ligation in multiple cell types. For endothelial and smooth muscle cells, the in vivo relevance of reverse MHC-I signaling has been established, namely in the context of adverse effects after tissue transplantation. For other cell types, the role of reverse MHC-I signaling is less clear, since aspects like the in vivo relevance, natural MHC-I ligands and the extended downstream pathways are not fully known.The existing evidence, however, suggests that reverse MHC-I signaling is involved in the regulation of the defense against bacterial and viral infections and against malignancies. Thereby, reverse MHC-I signaling is a potential target for therapies against viral and bacterial infections, cancer immunotherapies and management of organ transplantation outcomes.

Contains fulltext : 229361.pdf (publisher's version ) (Open Access), The contribution of dendritic cell (DC) antigen cross-presentation to the activation of CD8(+) T lymphocytes for immune defense against tumors, viruses, and intracellular pathogens has been recognized widely. Although originally thought to be an exclusive characteristic of DCs, recently also other immune cells, particularly macrophages, have been shown capable of cross-presentation. Here we provide an overview of in vitro and in vivo evidence on cross-presentation by macrophages. As we discuss, it is now firmly established that various types of tissue-resident macrophages are able to cross-present via similar cellular pathways as DCs. This is based on a wide range of antigens in macrophages from many different tissue origins such as blood, tumors, and lymphoid tissue. However, the physiological relevance of macrophage cross-presentation with potential contributions to activation of CD8(+) T lymphocytes is still mostly unknown. While cross-presentation by various types of proinflammatory macrophages might be involved in cross-priming of naive CD8(+) T lymphocytes, it might also be involved in local reactivation of memory and/or effector CD8(+) T lymphocytes. Moreover, cross-presentation by anti-inflammatory macrophages could be related to immune tolerance. Because cross-presentation promotes the initiation and potentiation of antigen-specific CD8(+) T lymphocyte responses, stimulating macrophages to cross-present antigen might be a promising strategy for antitumor or antiviral therapies.

Contains fulltext : 225799.pdf (publisher's version ) (Open Access), Glycosylation is an important post-translational modification for both intracellular and secreted proteins. For glycosylation to occur, cargo must be transported after synthesis through the different compartments of the Golgi apparatus where distinct monosaccharides are sequentially bound and trimmed, resulting in increasingly complex branched glycan structures. Of utmost importance for this process is the intraorganellar environment of the Golgi. Each Golgi compartment has a distinct pH, which is maintained by the vacuolar H(+)-ATPase (V-ATPase). Moreover, tethering factors such as Golgins and the conserved oligomeric Golgi (COG) complex, in concert with coatomer (COPI) and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion, efficiently deliver glycosylation enzymes to the right Golgi compartment. Together, these factors maintain intra-Golgi trafficking of proteins involved in glycosylation and thereby enable proper glycosylation. However, pathogenic mutations in these factors can cause defective glycosylation and lead to diseases with a wide variety of symptoms such as liver dysfunction and skin and bone disorders. Collectively, this group of disorders is known as congenital disorders of glycosylation (CDG). Recent technological advances have enabled the robust identification of novel CDGs related to membrane trafficking components. In this review, we highlight differences and similarities between membrane trafficking-related CDGs.

Contains fulltext : 229361.pdf (publisher's version ) (Open Access), The contribution of dendritic cell (DC) antigen cross-presentation to the activation of CD8(+) T lymphocytes for immune defense against tumors, viruses, and intracellular pathogens has been recognized widely. Although originally thought to be an exclusive characteristic of DCs, recently also other immune cells, particularly macrophages, have been shown capable of cross-presentation. Here we provide an overview of in vitro and in vivo evidence on cross-presentation by macrophages. As we discuss, it is now firmly established that various types of tissue-resident macrophages are able to cross-present via similar cellular pathways as DCs. This is based on a wide range of antigens in macrophages from many different tissue origins such as blood, tumors, and lymphoid tissue. However, the physiological relevance of macrophage cross-presentation with potential contributions to activation of CD8(+) T lymphocytes is still mostly unknown. While cross-presentation by various types of proinflammatory macrophages might be involved in cross-priming of naive CD8(+) T lymphocytes, it might also be involved in local reactivation of memory and/or effector CD8(+) T lymphocytes. Moreover, cross-presentation by anti-inflammatory macrophages could be related to immune tolerance. Because cross-presentation promotes the initiation and potentiation of antigen-specific CD8(+) T lymphocyte responses, stimulating macrophages to cross-present antigen might be a promising strategy for antitumor or antiviral therapies.

Contains fulltext : 206959.pdf (publisher's version ) (Closed access), We have previously shown that the chromogranin A (CgA)-derived peptide catestatin (CST: hCgA352-372) inhibits nicotine-induced secretion of catecholamines from the adrenal medulla and chromaffin cells. In the present study, we seek to determine whether CST regulates dense core (DC) vesicle (DCV) quanta (catecholamine and chromogranin/secretogranin proteins) during acute (0.5-h treatment) or chronic (24-h treatment) cholinergic (nicotine) or peptidergic (PACAP, pituitary adenylyl cyclase activating polypeptide) stimulation of PC12 cells. In acute experiments, we found that both nicotine (60 muM) and PACAP (0.1 muM) decreased intracellular norepinephrine (NE) content and increased (3)H-NE secretion, with both effects markedly inhibited by co-treatment with CST (2 muM). In chronic experiments, we found that nicotine and PACAP both reduced DCV and DC diameters and that this effect was likewise prevented by CST. Nicotine or CST alone increased expression of CgA protein and together elicited an additional increase in CgA protein, implying that nicotine and CST utilize separate signaling pathways to activate CgA expression. In contrast, PACAP increased expression of CgB and SgII proteins, with a further potentiation by CST. CST augmented the expression of tyrosine hydroxylase (TH) but did not increase intracellular NE levels, presumably due to its inability to cause post-translational activation of TH through serine phosphorylation. Co-treatment of CST with nicotine or PACAP increased quantal size, plausibly due to increased synthesis of CgA, CgB and SgII by CST. We conclude that CST regulates DCV quanta by acutely inhibiting catecholamine secretion and chronically increasing expression of CgA after nicotinic stimulation and CgB and SgII after PACAPergic stimulation.

Contains fulltext : 206946.pdf (publisher's version ) (Open Access), The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) syntaxin 5 (Stx5) in mammals and its ortholog Sed5p in Saccharomyces cerevisiae mediate anterograde and retrograde endoplasmic reticulum (ER)-Golgi trafficking. Stx5 and Sed5p are structurally highly conserved and are both regulated by interactions with other ER-Golgi SNARE proteins, the Sec1/Munc18-like protein Scfd1/Sly1p and the membrane tethering complexes COG, p115, and GM130. Despite these similarities, yeast Sed5p and mammalian Stx5 are differently recruited to COPII-coated vesicles, and Stx5 interacts with the microtubular cytoskeleton, whereas Sed5p does not. In this review, we argue that these different Stx5 interactions contribute to structural differences in ER-Golgi transport between mammalian and yeast cells. Insight into the function of Stx5 is important given its essential role in the secretory pathway of eukaryotic cells and its involvement in infections and neurodegenerative diseases.

Contains fulltext : 202589.pdf (publisher's version ) (Open Access)

Radboud University, 10 oktober 2019, Promotores : Figdor, C.G., Radstake, T.R.D.J., Bogaart, G. van den Co-promotor : Marut, W., Contains fulltext : 207618.pdf (publisher's version ) (Open Access)

Contains fulltext : 204223.pdf (publisher's version ) (Open Access)

Contains fulltext : 209354.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, Immune-cell activation by inflammatory stimuli triggers the transcription and translation of large amounts of cytokines. The transport of newly synthesized cytokines to the plasma membrane by vesicular trafficking can be rate-limiting for the production of these cytokines, and immune cells upregulate their exocytic machinery concomitantly with increased cytokine expression in order to cope with the increasing demand for trafficking. Whereas it is logical that trafficking is rate-limiting for regulated secretion where an intracellular pool of molecules is waiting to be released, the reason for this is not obvious for constitutively secreted cytokines, such as interleukin-6 (IL-6), interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF-alpha). These constitutively secreted cytokines are primarily regulated at the transcriptional and/or translational level but mounting evidence presented here shows that cells might also increase or decrease the rate of post-Golgi cytokine trafficking to modulate their production. Therefore, in this Hypothesis, we ask the question: why is there a need to limit the trafficking of constitutively secreted cytokines? We propose a model where cells monitor and adjust their production rate of cytokines by sensing the intracellular level of cytokines while they are in transit to the plasma membrane. This self-regulation of cytokine production could prevent an overshooting response of acute-phase cytokines, such as IL-6, IL-12 and TNF-alpha, upon acute infection.

Radboud University, 4 september 2019, Promotores : Figdor, C.G., Bogaart, G. van den, Contains fulltext : 206197.pdf (publisher's version ) (Open Access)

Contains fulltext : 201259.pdf (publisher's version ) (Open Access)

Contains fulltext : 206940.pdf (publisher's version ) (Open Access), Solid tumors grow at a high speed leading to insufficient blood supply to tumor cells. This makes the tumor hypoxic, resulting in the Warburg effect and an increased generation of reactive oxygen species (ROS). Hypoxia and ROS affect immune cells in the tumor micro-environment, thereby affecting their immune function. Here, we review the known effects of hypoxia and ROS on the function and physiology of dendritic cells (DCs). DCs can (cross-)present tumor antigen to activate naive T cells, which play a pivotal role in anti-tumor immunity. ROS might enter DCs via aquaporins in the plasma membrane, diffusion across the plasma membrane or via extracellular vesicles (EVs) released by tumor cells. Hypoxia and ROS exert complex effects on DCs, and can both inhibit and activate maturation of immature DCs. Furthermore, ROS transferred by EVs and/or produced by the DC can both promote antigen (cross-)presentation through phagosomal alkalinization, which preserves antigens by inhibiting proteases, and by direct oxidative modification of proteases. Hypoxia leads to a more migratory and inflammatory DC phenotype. Lastly, hypoxia alters DCs to shift the T- cell response towards a tumor suppressive Th17 phenotype. From numerous studies, the concept is emerging that hypoxia and ROS are mutually dependent effectors on DC function in the tumor micro-environment. Understanding their precise roles and interplay is important given that an adaptive immune response is required to clear tumor cells.

Contains fulltext : 206946.pdf (publisher's version ) (Open Access), The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) syntaxin 5 (Stx5) in mammals and its ortholog Sed5p in Saccharomyces cerevisiae mediate anterograde and retrograde endoplasmic reticulum (ER)-Golgi trafficking. Stx5 and Sed5p are structurally highly conserved and are both regulated by interactions with other ER-Golgi SNARE proteins, the Sec1/Munc18-like protein Scfd1/Sly1p and the membrane tethering complexes COG, p115, and GM130. Despite these similarities, yeast Sed5p and mammalian Stx5 are differently recruited to COPII-coated vesicles, and Stx5 interacts with the microtubular cytoskeleton, whereas Sed5p does not. In this review, we argue that these different Stx5 interactions contribute to structural differences in ER-Golgi transport between mammalian and yeast cells. Insight into the function of Stx5 is important given its essential role in the secretory pathway of eukaryotic cells and its involvement in infections and neurodegenerative diseases.

Contains fulltext : 202589.pdf (publisher's version ) (Open Access)

Radboud University, 10 oktober 2019, Promotores : Figdor, C.G., Radstake, T.R.D.J., Bogaart, G. van den Co-promotor : Marut, W., Contains fulltext : 207618.pdf (publisher's version ) (Open Access)

Contains fulltext : 204223.pdf (publisher's version ) (Open Access)

Contains fulltext : 209354.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, Immune-cell activation by inflammatory stimuli triggers the transcription and translation of large amounts of cytokines. The transport of newly synthesized cytokines to the plasma membrane by vesicular trafficking can be rate-limiting for the production of these cytokines, and immune cells upregulate their exocytic machinery concomitantly with increased cytokine expression in order to cope with the increasing demand for trafficking. Whereas it is logical that trafficking is rate-limiting for regulated secretion where an intracellular pool of molecules is waiting to be released, the reason for this is not obvious for constitutively secreted cytokines, such as interleukin-6 (IL-6), interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF-alpha). These constitutively secreted cytokines are primarily regulated at the transcriptional and/or translational level but mounting evidence presented here shows that cells might also increase or decrease the rate of post-Golgi cytokine trafficking to modulate their production. Therefore, in this Hypothesis, we ask the question: why is there a need to limit the trafficking of constitutively secreted cytokines? We propose a model where cells monitor and adjust their production rate of cytokines by sensing the intracellular level of cytokines while they are in transit to the plasma membrane. This self-regulation of cytokine production could prevent an overshooting response of acute-phase cytokines, such as IL-6, IL-12 and TNF-alpha, upon acute infection.