scholarly journals Qa-SNARE Protein SYP22 Negatively Regulates Brassinosteroid Signaling in the Dark

2015 ◽  
Vol 57 (2) ◽  
pp. 79-88
Author(s):  
Ting Shan Yao ◽  
Xiao Feng Zhu ◽  
Jin Hee Jung ◽  
Yuan Hu Xuan
Keyword(s):  
Marker Gene ◽  
Adaptor Protein ◽  
Hypocotyl Growth ◽  
Protein Receptor ◽  
Brassinosteroid Signaling ◽  
Sensitive Factor ◽  
Shoot Gravitropism ◽  
Bri1 Mutant ◽  
Pleiotropic Function

Abstract Soluble N-ethyl-maleimide sensitive factor attachment adaptor protein receptor (SNARE) domain-containing proteins were mainly involved in vesicle-associated membrane fusion. Genetic screening has revealed the function of SNARE in different aspects of plant biology. Among them, Synthaxin-22 (SYP22) a Qa-SNARE has been reported to have a pleiotropic function in plant development including regulation of leaf waving, shoot gravitropism and flowering time. In this study, we identified a new role of SYP22 in regulation of brassinosteroid (BR) signaling, especially in the dark. SYP22 interacts with BR receptor, brassinosteroid insensitive 1 (BRI1), and overexpression of SYP22 enhanced a weak BRI1 mutant bri1-5 phenotype. syp22 mutant exhibits short hypocotyl and it is sensitive to exogenously treated BR while slightly insensitive to BR-biosynthesis inhibitor propiconazole (PCZ) in the dark. Expression levels of BR signaling maker genes ACS5, SAUR15 and IAA19 were slightly higher, while BR6OX2, a BR biosynthesis marker gene, was lower in syp22 compared to the wild-type. In addition, syp22 was sensitive to 2,4-D, a synthetic auxin, in the dark. In conclusion, SYP22 is involved in BR- and auxin-mediated hypocotyl growth inhibition in the dark, which might be via interaction with BR and auxin key regulators to alter their internalization in Arabidopsis.

scholarly journals SNAP-23 regulates phagosome formation and maturation in macrophages

2012 ◽  
Vol 23 (24) ◽  
pp. 4849-4863 ◽  
Author(s):  
Chiye Sakurai ◽  
Hitoshi Hashimoto ◽  
Hideki Nakanishi ◽  
Seisuke Arai ◽  
Yoh Wada ◽  
...  
Keyword(s):  
Critical Role ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Nadph Oxidase Complex ◽  
Uptake Activity ◽  
Fret Efficiency ◽  
Precise Role

Synaptosomal associated protein of 23 kDa (SNAP-23), a plasma membrane–localized soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE), has been implicated in phagocytosis by macrophages. For elucidation of its precise role in this process, a macrophage line overexpressing monomeric Venus–tagged SNAP-23 was established. These cells showed enhanced Fc receptor–mediated phagocytosis. Detailed analyses of each process of phagocytosis revealed a marked increase in the production of reactive oxygen species within phagosomes. Also, enhanced accumulation of a lysotropic dye, as well as augmented quenching of a pH-sensitive fluorophore were observed. Analyses of isolated phagosomes indicated the critical role of SNAP-23 in the functional recruitment of the NADPH oxidase complex and vacuolar-type H+-ATPase to phagosomes. The data from the overexpression experiments were confirmed by SNAP-23 knockdown, which demonstrated a significant delay in phagosome maturation and a reduction in uptake activity. Finally, for analyzing whether phagosomal SNAP-23 entails a structural change in the protein, an intramolecular Förster resonance energy transfer (FRET) probe was constructed, in which the distance within a TagGFP2-TagRFP was altered upon close approximation of the N-termini of its two SNARE motifs. FRET efficiency on phagosomes was markedly enhanced only when VAMP7, a lysosomal SNARE, was coexpressed. Taken together, our results strongly suggest the involvement of SNAP-23 in both phagosome formation and maturation in macrophages, presumably by mediating SNARE-based membrane traffic.

scholarly journals Munc18-1 domain-1 controls vesicle docking and secretion by interacting with syntaxin-1 and chaperoning it to the plasma membrane

2011 ◽  
Vol 22 (21) ◽  
pp. 4134-4149 ◽  
Author(s):  
Gayoung A. Han ◽  
Nancy T. Malintan ◽  
Ner Mu Nar Saw ◽  
Lijun Li ◽  
Liping Han ◽  
...  
Keyword(s):  
Molecular Chaperone ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Attachment Protein ◽  
Vesicle Docking ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Intracellular Expression ◽  
Factor Attachment Protein Receptor

Munc18-1 plays pleiotropic roles in neurosecretion by acting as 1) a molecular chaperone of syntaxin-1, 2) a mediator of dense-core vesicle docking, and 3) a priming factor for soluble N-ethylmaleimide–sensitive factor attachment protein receptor–mediated membrane fusion. However, how these functions are executed and whether they are correlated remains unclear. Here we analyzed the role of the domain-1 cleft of Munc18-1 by measuring the abilities of various mutants (D34N, D34N/M38V, K46E, E59K, K46E/E59K, K63E, and E66A) to bind and chaperone syntaxin-1 and to restore the docking and secretion of dense-core vesicles in Munc18-1/-2 double-knockdown cells. We identified striking correlations between the abilities of these mutants to bind and chaperone syntaxin-1 with their ability to restore vesicle docking and secretion. These results suggest that the domain-1 cleft of Munc18-1 is essential for binding to syntaxin-1 and thereby critical for its chaperoning, docking, and secretory functions. Our results demonstrate that the effect of the alleged priming mutants (E59K, D34N/M38V) on exocytosis can largely be explained by their reduced syntaxin-1–chaperoning functions. Finally, our data suggest that the intracellular expression and distribution of syntaxin-1 determines the level of dense-core vesicle docking.

scholarly journals Insulin and Hypertonicity Recruit GLUT4 to the Plasma Membrane of Muscle Cells by Using N-Ethylmaleimide-sensitive Factor-dependent SNARE Mechanisms but Different v-SNAREs: Role of TI-VAMP

2004 ◽  
Vol 15 (12) ◽  
pp. 5565-5573 ◽  
Author(s):  
Varinder K. Randhawa ◽  
Farah S.L. Thong ◽  
Dawn Y. Lim ◽  
Dailin Li ◽  
Rami R. Garg ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Muscle Cells ◽  
Dominant Negative ◽  
Attachment Protein ◽  
Insulin Effect ◽  
Tetanus Neurotoxin ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Interfering Rna

Insulin and hypertonicity each increase the content of GLUT4 glucose transporters at the surface of muscle cells. Insulin enhances GLUT4 exocytosis without diminishing its endocytosis. The insulin but not the hypertonicity response is reduced by tetanus neurotoxin, which cleaves vesicle-associated membrane protein (VAMP)2 and VAMP3, and is rescued upon introducing tetanus neurotoxin-resistant VAMP2. Here, we show that hypertonicity enhances GLUT4 recycling, compounding its previously shown ability to reduce GLUT4 endocytosis. To examine whether the canonical soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) mechanism is required for the plasma membrane fusion of the tetanus neurotoxin-insensitive GLUT4 vesicles, L6 myoblasts stably expressing myc-tagged GLUT4 (GLUT4myc) were transiently transfected with dominant negative N-ethylmaleimide-sensitive factor (NSF) (DN-NSF) or small-interfering RNA to tetanus neurotoxin-insensitive VAMP (TI-VAMP siRNA). Both strategies markedly reduced the basal level of surface GLUT4myc and the surface gain of GLUT4myc in response to hypertonicity. The insulin effect was abolished by DN-NSF, but only partly reduced by TI-VAMP siRNA. We propose that insulin and hypertonicity recruit GLUT4myc from partly overlapping, but distinct sources defined by VAMP2 and TI-VAMP, respectively.

Renin release: role of SNAREs

2014 ◽  
Vol 307 (5) ◽  
pp. R484-R486 ◽  
Author(s):  
Mariela Mendez
Keyword(s):  
Molecular Mechanism ◽  
Current Knowledge ◽  
Renin Release ◽  
Juxtaglomerular Cells ◽  
Attachment Protein ◽  
Granule Exocytosis ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Factor Attachment Protein Receptor

Little is known about the molecular mechanism mediating renin granule exocytosis and the identity of proteins involved. We previously showed that soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNAREs), a family of proteins required for exocytosis, mediate the stimulated release of renin from juxtaglomerular cells. This minireview focuses on the current knowledge of the proteins that facilitate renin-granule exocytosis. We discuss the identity of potential candidates that mediate the signaling and final steps of exocytosis of the renin granule.

scholarly journals Interaction Between Photoreceptors and BR Signaling in Arabidopsis

2015 ◽  
Vol 56 (2) ◽  
pp. 126-136 ◽  
Author(s):  
Zhong Xin Zhu ◽  
Xiao Feng Zhu ◽  
Yu Ting Zhu ◽  
Da Nian Yao ◽  
Yuan Hu Xuan
Keyword(s):  
Gene Regulation ◽  
Plant Growth ◽  
Plant Development ◽  
Marker Gene ◽  
Important Class ◽  
Hypocotyl Growth ◽  
Dominant Mutant ◽  
Quadruple Mutant ◽  
Growth Development

Abstract Extensive studies have been performed to elucidate the role of brassinosteroids (BRs), an important class of phy-tohormone in plant growth, development, and photomorphogenesis. Different wavelengths of light recognized by photoreceptors play a crucial role in plant development. The role of different photoreceptors in BR signaling has not been analyzed. Here we used photoreceptor single mutants, double mutants and even a quadruple mutant to analyze BR-dependent hypocotyl growth and gene regulation. All the photoreceptor mutants differed from the controls in their response to BR, and hypocotyl elongation as well as BR marker gene regulation were inhibited by application of propiconazole (PCZ), a BR biosynthesis inhibitor. In addition, altered Phytochrome and Cryptochrome expression in brassinosteroid insensitive 1 mutant bri1-5 and brassinazole-resistant 1 dominant mutant bzr1-D indicated that BR negatively regulates photoreceptors in transcriptional levels. This is the first study to investigate the connections between BR and photoreceptors in Arabidopsis.

scholarly journals Prefused lysosomes cluster on autophagosomes regulated by VAMP8

2021 ◽  
Vol 12 (10) ◽  
Author(s):  
Qixin Chen ◽  
Mingang Hao ◽  
Lei Wang ◽  
Linsen Li ◽  
Yang Chen ◽  
...  
Keyword(s):  
Potential Role ◽  
Autophagic Flux ◽  
Snare Protein ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Fusion Probability ◽  
Autophagosome Maturation ◽  
Factor Attachment Protein Receptor

AbstractLysosome–autophagosome fusion is critical to autophagosome maturation. Although several proteins that regulate this fusion process have been identified, the prefusion architecture and its regulation remain unclear. Herein, we show that upon stimulation, multiple lysosomes form clusters around individual autophagosomes, setting the stage for membrane fusion. The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein on lysosomes—vesicle-associated membrane protein 8 (VAMP8)—plays an important role in forming this prefusion state of lysosomal clusters. To study the potential role of phosphorylation on spontaneous fusion, we investigated the effect of phosphorylation of C-terminal residues of VAMP8. Using a phosphorylation mimic, we observed a decrease of fusion in an ensemble lipid mixing assay and an increase of unfused lysosomes associated with autophagosomes. These results suggest that phosphorylation not only reduces spontaneous fusion for minimizing autophagic flux under normal conditions, but also preassembles multiple lysosomes to increase the fusion probability for resuming autophagy upon stimulation. VAMP8 phosphorylation may thus play an important role in chemotherapy drug resistance by influencing autophagosome maturation.

scholarly journals The SNAP-25 Linker as an Adaptation Toward Fast Exocytosis

2008 ◽  
Vol 19 (9) ◽  
pp. 3769-3781 ◽  
Author(s):  
Gábor Nagy ◽  
Ira Milosevic ◽  
Ralf Mohrmann ◽  
Katrin Wiederhold ◽  
Alexander M. Walter ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Fusion Rate ◽  
High Rate ◽  
Fusion Pore ◽  
Chimeric Proteins ◽  
Null Mouse ◽  
Charged Amino Acids ◽  
Protein Receptor ◽  
Sensitive Factor

The assembly of four soluble N-ethylmaleimide-sensitive factor attachment protein receptor domains into a complex is essential for membrane fusion. In most cases, the four SNARE-domains are encoded by separate membrane-targeted proteins. However, in the exocytotic pathway, two SNARE-domains are present in one protein, connected by a flexible linker. The significance of this arrangement is unknown. We characterized the role of the linker in SNAP-25, a neuronal SNARE, by using overexpression techniques in synaptosomal-associated protein of 25 kDa (SNAP-25) null mouse chromaffin cells and fast electrophysiological techniques. We confirm that the palmitoylated linker-cysteines are important for membrane association. A SNAP-25 mutant without cysteines supported exocytosis, but the fusion rate was slowed down and the fusion pore duration prolonged. Using chimeric proteins between SNAP-25 and its ubiquitous homologue SNAP-23, we show that the cysteine-containing part of the linkers is interchangeable. However, a stretch of 10 hydrophobic and charged amino acids in the C-terminal half of the SNAP-25 linker is required for fast exocytosis and in its absence the calcium dependence of exocytosis is shifted toward higher concentrations. The SNAP-25 linker therefore might have evolved as an adaptation toward calcium triggering and a high rate of execution of the fusion process, those features that distinguish exocytosis from other membrane fusion pathways.

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