Mast cells possess distinct secretory granule subsets whose exocytosis is regulated by different SNARE isoforms

Puri, Niti; Roche, Paul A.

doi:10.1073/pnas.0707854105

Cited by 191 publications

(205 citation statements)

References 20 publications

(34 reference statements)

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“…We first confirmed the role of VAMP8 in secretion by showing that knockdown of VAMP8 reduced secretion, similar to previous mast cell studies (Lippert et al , 2007; Puri & Roche, 2008; Tiwari et al , 2008), and that this effect could be rescued with wild‐type VAMP8 (Figs 4A and EV5D and E). Of note, the sequence homolog VAMP3, VAMP4, and VAMP7 did not rescue the secretion defect in cells with siRNA knockdown of endogenous VAMP8 (Fig EV5F).…”

Section: Resultssupporting

confidence: 89%

“…Markedly, this pruned list contained 2 phosphopeptides from a 100 amino acid long SNARE protein (Figs 1F and EV2C), vesicular‐associated membrane protein 8 (VAMP8), that is known to be critical for the fusion of vesicles with the plasma membrane during mast cell secretion (Lippert et al , 2007; Puri & Roche, 2008; Tiwari et al , 2008) but was not previously known to be regulated by phosphorylation. Using antibody staining, we confirmed that VAMP8 localizes to secretory granules before stimulation and translocates to the plasma membrane after antigen stimulation (Fig 1G).…”

Section: Resultsmentioning

confidence: 99%

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Phosphorylation of residues inside the SNARE complex suppresses secretory vesicle fusion

et al. 2016

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Membrane fusion is essential for eukaryotic life, requiring SNARE proteins to zipper up in an α‐helical bundle to pull two membranes together. Here, we show that vesicle fusion can be suppressed by phosphorylation of core conserved residues inside the SNARE domain. We took a proteomics approach using a PKCB knockout mast cell model and found that the key mast cell secretory protein VAMP8 becomes phosphorylated by PKC at multiple residues in the SNARE domain. Our data suggest that VAMP8 phosphorylation reduces vesicle fusion in vitro and suppresses secretion in living cells, allowing vesicles to dock but preventing fusion with the plasma membrane. Markedly, we show that the phosphorylation motif is absent in all eukaryotic neuronal VAMPs, but present in all other VAMPs. Thus, phosphorylation of SNARE domains is a general mechanism to restrict how much cells secrete, opening the door for new therapeutic strategies for suppression of secretion.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Phosphorylation of residues inside the SNARE complex suppresses secretory vesicle fusion

et al. 2016

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“…Hence, caspase-3 appears to be present in secretory vesicles distinct from those that are released by IgE-mediated mechanisms. Clearly, this may be in line with recent studies that have identified granule subtypes of distinct contents in mast cells (31).…”

Section: Discussionsupporting

confidence: 77%

Active Caspase-3 Is Stored within Secretory Compartments of Viable Mast Cells

Garcia-Faroldi

Melo

Rönnberg

et al. 2013

The Journal of Immunology

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Caspase-3 is a main executioner of apoptotic cell death. The general notion is that, in viable cells, caspase-3 is found as a cytosolic inactive proenzyme and that caspase-3 activation is largely confined to processes associated with cell death. In this study, we challenge this notion by showing that enzymatically active caspase-3 is stored in viable mast cells. The enzymatically active caspase-3 was undetectable in the cytosol of viable cells, but was recovered in subcellular fractions containing secretory granule-localized proteases. Moreover, active caspase-3 was rapidly released into the cytosolic compartment after permeabilization of the secretory granules. Using a cell-permeable substrate for caspase-3, the presence of active caspase-3–like activity in granule-like compartments close to the plasma membrane was demonstrated. Moreover, it was shown that mast cell activation caused release of the caspase-3 to the cell exterior. During the course of mast cell differentiation from bone marrow cells, procaspase-3 was present in cells of all stages of maturation. In contrast, active caspase-3 was undetectable in bone marrow precursor cells, but increased progressively during the process of mast cell maturation, its accumulation coinciding with that of a mast cell–specific secretory granule marker, mouse mast cell protease 6. Together, the current study suggests that active caspase-3 can be stored within secretory compartments of viable mast cells.

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“…The exact localization of STX11 in mast cells is still unclear. It has been recognized that mast cells have different secretory granule subsets characterized by different SNARE proteins able to selectively lead their release [30]. Interestingly, neutrophils, a cell type with a dominant exocytosis activity and heterogeneous granules, show a diminished degranulation capacity in absence of STX11.…”

Section: Discussionmentioning

confidence: 99%

Syntaxin 11 is required for NK and CD8⁺ T‐cell cytotoxicity and neutrophil degranulation

et al. 2012

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Syntaxin 11 (STX11) controls vesicular trafficking and is a key player in exocytosis. SinceStx11 mutations are causally associated with a familial hemophagocytic lymphohistiocytosis, we wanted to clarify whether STX11 is functionally important for key immune cell populations. This was studied in primary cells obtained from newly generated Stx11 −/− mice. Our data revealed that STX11 is not only widely expressed in different immune cells, but also induced upon LPS or IFN-γ treatment. However, Stx11 deficiency does not affect macrophage phagocytic function and cytokine secretion, mast cell activation, or antigen presentation by DCs. Instead, STX11 selectively controls lymphocyte cytotoxicity in NK and activated CD8 + T cells and degranulation in neutrophils. Stx11 −/− NK cells and CTLs show impaired degranulation, despite a comparable activation, maturation and expression of the complex-forming partners MUNC18-2 and VTI1B. In addition, Stx11 −/− CTLs and NK cells produce abnormal levels of IFN-γ. Since functional reconstitution rescues the defective phenotype of Stx11 −/− CTLs, we suggest a direct, specific and key role of STX11 in controlling lymphocyte cytotoxicity, cytokine production and secretion. Finally, we show that these mice are a very useful tool for dissecting the role of STX11 in vesicular trafficking and secretion. Keywords: CTL r Cytokines r Exocytosis r N-ethylmaleimide-sensitive factor attachment protein receptorSee accompanying Commentary by Lopez and Voskoboinik.Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionSyntaxin 11 (STX11) belongs to the family of N-ethylmaleimidesensitive factor attachment protein receptor (SNARE) proteins Correspondence: Prof. Silvia Bulfone-Paus e-mail: sbulfone@fz-borstel.de and is involved in intracellular membrane trafficking events by interacting with other family members or by associating with membranes by palmitoylation of cysteine residues [1][2][3]. STX11 is expressed in a wide variety of cells including human monocytes/macrophages, neutrophils, B cells, NK cells and CD8 + T cells [2][3][4][5][6][7][8][9]. STX11 is enriched in immune tissues such as thymus, spleen C 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2013. 43: 194-208 Immunomodulation 195 Values represent the mean ± SEM percentage of cell subsets in the spleen (n = 8) and lymph nodes (WT n = 7; Stx11 −/− n = 6) and are the summary of three experiments performed.and lymph nodes, but lower levels of protein are detectable also in heart, kidney and liver [2]. STX11 localizes mainly in the vesicular tubular clusters, an organelle complex between the endoplasmic reticulum and the Golgi, and displays, in addition, a spotted staining pattern throughout the cell periphery [2,9]. While STX11 has been recognized to act as a negative regulator of both phagocytosis and intracellular trafficking between endosomes, lysosomes and the outer membrane in macrophages [6,9], in human NK cells and CTLs, ST...

show abstract

Mast cells possess distinct secretory granule subsets whose exocytosis is regulated by different SNARE isoforms

Cited by 191 publications

References 20 publications

Phosphorylation of residues inside the SNARE complex suppresses secretory vesicle fusion

Phosphorylation of residues inside the SNARE complex suppresses secretory vesicle fusion

Active Caspase-3 Is Stored within Secretory Compartments of Viable Mast Cells

Syntaxin 11 is required for NK and CD8⁺ T‐cell cytotoxicity and neutrophil degranulation

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Mast cells possess distinct secretory granule subsets whose exocytosis is regulated by different SNARE isoforms

Cited by 191 publications

References 20 publications

Phosphorylation of residues inside the SNARE complex suppresses secretory vesicle fusion

Phosphorylation of residues inside the SNARE complex suppresses secretory vesicle fusion

Active Caspase-3 Is Stored within Secretory Compartments of Viable Mast Cells

Syntaxin 11 is required for NK and CD8+ T‐cell cytotoxicity and neutrophil degranulation

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Syntaxin 11 is required for NK and CD8⁺ T‐cell cytotoxicity and neutrophil degranulation