The Experts below are selected from a list of 10653 Experts worldwide ranked by ideXlab platform
Pamela L Tuma - One of the best experts on this subject based on the ideXlab platform.
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the gtp bound and sumoylated form of the rab17 small molecular weight gtpase selectively binds Syntaxin 2 in polarized hepatic wif b cells
Journal of Biological Chemistry, 2016Co-Authors: Anneliese C Striz, Pamela L TumaAbstract:Abstract A major focus for our laboratory is identifying the molecules and mechanisms that regulate polarized apical protein sorting in hepatocytes, the major epithelial cells of the liver. These trafficking pathways are regulated, in part, by small molecular weight rab GTPases. We chose to investigate rab17, whose expression is restricted to polarized epithelial cells, is enriched in liver and has been implicated in regulating basolateral to apical transcytosis. To initiate our studies, we generated three recombinant adenoviruses expressing wild type, constitutively active (GTP bound) or dominant negative (GDP bound) rab17. Immunoblotting revealed rab17 immunoreactive species at 25 kDa (the predicted rab17 molecular weight) and 40 kDa. We determined that mono-sumoylation of the 25 kDa rab17 is responsible for the shift in molecular weight, and that rab17 prenylation is required for sumoylation. We further determined that sumoylation selectively promotes interactions with Syntaxin 2 (but not Syntaxins 3 or 4) and that these interactions are nucleotide dependent. Furthermore, a K68R mutated rab17 led to the redistribution of Syntaxin 2 and 5&primenucleotidase (5&primeNT) from the apical membrane to sub-apical puncta whereas multidrug resistance protein 2 (MRP2) distributions were not changed. Together these data are consistent with rab17&primes proposed role in vesicle fusion with the apical plasma membrane and further implicate sumoylation as an important mediator of protein-protein interactions. The selectivity in Syntaxin binding and apical protein redistribution further suggests that rab17 and Syntaxin 2 mediate fusion of transcytotic vesicles at the apical surface.
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the gtp bound and sumoylated form of the rab17 small molecular weight gtpase selectively binds Syntaxin 2 in polarized hepatic wif b cells
Journal of Biological Chemistry, 2016Co-Authors: Anneliese C Striz, Pamela L TumaAbstract:A major focus for our laboratory is identifying the molecules and mechanisms that regulate polarized apical protein sorting in hepatocytes, the major epithelial cells of the liver. These trafficking pathways are regulated, in part, by small molecular weight rab GTPases. We chose to investigate rab17, whose expression is restricted to polarized epithelial cells, is enriched in liver, and has been implicated in regulating basolateral to apical transcytosis. To initiate our studies, we generated three recombinant adenoviruses expressing wild type, constitutively active (GTP bound), or dominant-negative (GDP bound) rab17. Immunoblotting revealed rab17 immunoreactive species at 25 kDa (the predicted rab17 molecular mass) and 40 kDa. We determined that mono-sumoylation of the 25-kDa rab17 is responsible for the shift in molecular mass, and that rab17 prenylation is required for sumoylation. We further determined that sumoylation selectively promotes interactions with Syntaxin 2 (but not Syntaxins 3 or 4) and that these interactions are nucleotide dependent. Furthermore, a K68R-mutated rab17 led to the redistribution of Syntaxin 2 and 5′ nucleotidase from the apical membrane to subapical puncta, whereas multidrug resistance protein 2 distributions were not changed. Together these data are consistent with the proposed role of rab17 in vesicle fusion with the apical plasma membrane and further implicate sumoylation as an important mediator of protein-protein interactions. The selectivity in Syntaxin binding and apical protein redistribution further suggests that rab17 and Syntaxin 2 mediate fusion of transcytotic vesicles at the apical surface.
Derek C Radisky - One of the best experts on this subject based on the ideXlab platform.
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homology with vesicle fusion mediator Syntaxin 1a predicts determinants of epimorphin Syntaxin 2 function in mammary epithelial morphogenesis
Journal of Biological Chemistry, 2009Co-Authors: Connie S Chen, Celeste M Nelson, Davitte Khauv, Simone Bennett, Evette S Radisky, Yohei Hirai, Mina J Bissell, Derek C RadiskyAbstract:We have shown that branching morphogenesis of mammary ductal structures requires the action of the morphogen epimorphin/Syntaxin-2. Epimorphin, originally identified as an extracellular molecule, is identical to Syntaxin-2, an intracellular molecule that is a member of the extensively investigated Syntaxin family of proteins that mediate vesicle trafficking. We show here that, although epimorphin/Syntaxin-2 is highly homologous to Syntaxin-1a, only epimorphin/Syntaxin-2 can stimulate mammary branching morphogenesis. We construct a homology model of epimorphin/Syntaxin-2 based on the published structure of Syntaxin-1a, and we use this model to identify the structural motif responsible for the morphogenic activity. We identify four residues located within the cleft between helices B and C that differ between Syntaxin-1a and epimorphin/Syntaxin-2; through site-directed mutagenesis of these four amino acids, we confer the properties of epimorphin for cell adhesion, gene activation, and branching morphogenesis onto the inactive Syntaxin-1a template. These results provide a dramatic demonstration of the use of structural information about one molecule to define a functional motif of a second molecule that is related at the sequence level but highly divergent functionally.
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extracellular localization of epimorphin Syntaxin 2
Blood, 2007Co-Authors: Yohei Hirai, Mina J Bissell, Derek C RadiskyAbstract:To the editor: In a recent article, Flaumenhaft et al[1][1] showed that Syntaxin-2 is found on the extracellular cell surface on activated platelets. While they conclude that theirs is the first demonstration of extracellular presentation of a Syntaxin molecule, it should be noted that the Syntaxin
Michael J Edwardson - One of the best experts on this subject based on the ideXlab platform.
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identification of snares that mediate zymogen granule exocytosis
Biochemical and Biophysical Research Communications, 2007Co-Authors: James A Pickett, Manuel Campostoimil, Paul Thomas, Michael J EdwardsonAbstract:A secretagogue-stimulated pancreatic acinar cell releases digestive enzymes from its apical pole. We attempted to identify the SNAREs involved in zymogen granule exocytosis. Antibodies against Syntaxins 2 and 3, SNAP-23 and VAMP 8, and the corresponding recombinant SNAREs, inhibited amylase secretion from streptolysin O-permeabilised acini; other anti-SNARE antibodies and SNAREs had no effect. Botulinum neurotoxin C, which cleaved Syntaxin 2 and (to a lesser extent) Syntaxin 3, but not Syntaxins 4, 7 or 8, also inhibited exocytosis. We propose that Syntaxin 2, SNAP-23 and VAMP 8 mediate primary granule-plasma membrane fusion. Syntaxin 3 may be involved in secondary granule-granule fusion.
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the plasma membrane q snare Syntaxin 2 enters the zymogen granule membrane during exocytosis in the pancreatic acinar cell
Journal of Biological Chemistry, 2005Co-Authors: James A Pickett, Peter Thorn, Michael J EdwardsonAbstract:Abstract During exocytosis in the pancreatic acinar cell, zymogen granules fuse directly with the apical plasma membrane and also with granules that have themselves fused with the plasma membrane. Together, these primary and secondary fusion events constitute the process of compound exocytosis. It has been suggested that the sequential nature of primary and secondary fusion is a consequence of the requirement for plasma membrane soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors, such as Syntaxin 2, to enter the membrane of the primary fused granule. We have tested this possibility by determining the location of Syntaxin 2 in unstimulated and stimulated pancreatic acini. Syntaxin 2 was imaged by confocal immunofluorescence microscopy. Fused granules were detected both through their filling with the aqueous dye lysine-fixable Texas Red-dextran and through the decoration of their cytoplasmic surfaces with filamentous actin. In unstimulated cells, Syntaxin 2 was exclusively present on the apical plasma membrane. In contrast, after stimulation, Syntaxin 2 had moved into the membranes of fused granules, as judged by its location around dye-filled structures of 1-μm diameter that were coated with filamentous actin. At long times of stimulation (5 min), the majority (85%) of dye-filled granules were also positive for Syntaxin 2. In contrast, at shorter times (1 min), more dye-filled granules (29%) were Syntaxin 2-negative. We conclude that Syntaxin 2 enters the membrane of a fused zymogen granule after the opening of the fusion pore, and we suggest that this movement might permit the onset of secondary fusion.
Ruben Bierings - One of the best experts on this subject based on the ideXlab platform.
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interaction networks of weibel palade body regulators Syntaxin 3 and Syntaxin binding protein 5 in endothelial cells
Journal of Proteomics, 2019Co-Authors: Maaike Schillemans, Ruben Bierings, Ellie Karampini, Floris P. J. Van Alphen, Maartje Van Den Biggelaar, Jan Voorberg, Arie J Hoogendijk, Maryam WahediAbstract:The endothelium stores the hemostatic protein Von Willebrand factor (VWF) in endothelial storage organelles called Weibel-Palade bodies (WPBs). During maturation, WPBs recruit a complex of Rab GTPases and effectors that associate with components of the SNARE machinery that control WPB exocytosis. Recent genome wide association studies have found links between genetic variations in the SNAREs Syntaxin-2 (STX2) and Syntaxin binding protein 5 (STXBP5) and VWF plasma levels, suggesting a role for SNARE proteins in regulating VWF release. Moreover, we have previously identified the SNARE proteins Syntaxin-3 and STXBP1 as regulators of WPB release. In this study we used an unbiased iterative interactomic approach to identify new components of the WPB exocytotic machinery. An interactome screen of Syntaxin-3 identifies a number of SNAREs and SNARE associated proteins (STXBP2, STXBP5, SNAP23, NAPA and NSF). We show that the VAMP-like domain (VLD) of STXBP5 is indispensable for the interaction with SNARE proteins and this capacity of the VLD could be exploited to identify an extended set of novel endothelial SNARE interactors of STXBP5. In addition, an STXBP5 variant with an N436S substitution, which is linked to lower VWF plasma levels, does not show a difference in interactome when compared with WT STXBP5. Significance: The hemostatic protein Von Willebrand factor plays a pivotal role in vascular health: quantitative or qualitative deficiencies of VWF can lead to bleeding, while elevated levels of VWF are associated with increased risk of thrombosis. Tight regulation of VWF secretion from WPBs is therefore essential to maintain vascular homeostasis. We used an unbiased proteomic screen to identify new components of the regulatory machinery that controls WPB exocytosis. Our data expand the endothelial SNARE protein network and provide a set of novel candidate WPB regulators that may contribute to regulation of VWF plasma levels and vascular health.
Anneliese C Striz - One of the best experts on this subject based on the ideXlab platform.
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the gtp bound and sumoylated form of the rab17 small molecular weight gtpase selectively binds Syntaxin 2 in polarized hepatic wif b cells
Journal of Biological Chemistry, 2016Co-Authors: Anneliese C Striz, Pamela L TumaAbstract:Abstract A major focus for our laboratory is identifying the molecules and mechanisms that regulate polarized apical protein sorting in hepatocytes, the major epithelial cells of the liver. These trafficking pathways are regulated, in part, by small molecular weight rab GTPases. We chose to investigate rab17, whose expression is restricted to polarized epithelial cells, is enriched in liver and has been implicated in regulating basolateral to apical transcytosis. To initiate our studies, we generated three recombinant adenoviruses expressing wild type, constitutively active (GTP bound) or dominant negative (GDP bound) rab17. Immunoblotting revealed rab17 immunoreactive species at 25 kDa (the predicted rab17 molecular weight) and 40 kDa. We determined that mono-sumoylation of the 25 kDa rab17 is responsible for the shift in molecular weight, and that rab17 prenylation is required for sumoylation. We further determined that sumoylation selectively promotes interactions with Syntaxin 2 (but not Syntaxins 3 or 4) and that these interactions are nucleotide dependent. Furthermore, a K68R mutated rab17 led to the redistribution of Syntaxin 2 and 5&primenucleotidase (5&primeNT) from the apical membrane to sub-apical puncta whereas multidrug resistance protein 2 (MRP2) distributions were not changed. Together these data are consistent with rab17&primes proposed role in vesicle fusion with the apical plasma membrane and further implicate sumoylation as an important mediator of protein-protein interactions. The selectivity in Syntaxin binding and apical protein redistribution further suggests that rab17 and Syntaxin 2 mediate fusion of transcytotic vesicles at the apical surface.
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the gtp bound and sumoylated form of the rab17 small molecular weight gtpase selectively binds Syntaxin 2 in polarized hepatic wif b cells
Journal of Biological Chemistry, 2016Co-Authors: Anneliese C Striz, Pamela L TumaAbstract:A major focus for our laboratory is identifying the molecules and mechanisms that regulate polarized apical protein sorting in hepatocytes, the major epithelial cells of the liver. These trafficking pathways are regulated, in part, by small molecular weight rab GTPases. We chose to investigate rab17, whose expression is restricted to polarized epithelial cells, is enriched in liver, and has been implicated in regulating basolateral to apical transcytosis. To initiate our studies, we generated three recombinant adenoviruses expressing wild type, constitutively active (GTP bound), or dominant-negative (GDP bound) rab17. Immunoblotting revealed rab17 immunoreactive species at 25 kDa (the predicted rab17 molecular mass) and 40 kDa. We determined that mono-sumoylation of the 25-kDa rab17 is responsible for the shift in molecular mass, and that rab17 prenylation is required for sumoylation. We further determined that sumoylation selectively promotes interactions with Syntaxin 2 (but not Syntaxins 3 or 4) and that these interactions are nucleotide dependent. Furthermore, a K68R-mutated rab17 led to the redistribution of Syntaxin 2 and 5′ nucleotidase from the apical membrane to subapical puncta, whereas multidrug resistance protein 2 distributions were not changed. Together these data are consistent with the proposed role of rab17 in vesicle fusion with the apical plasma membrane and further implicate sumoylation as an important mediator of protein-protein interactions. The selectivity in Syntaxin binding and apical protein redistribution further suggests that rab17 and Syntaxin 2 mediate fusion of transcytotic vesicles at the apical surface.
