Complexin II facilitates exocytotic release in mast cells by enhancing Ca2+ sensitivity of the fusion process

Tadokoro, Satoshı; Nakanishi, Mamoru; Hirashima, Naohide

doi:10.1242/jcs.02338

Cited by 61 publications

(68 citation statements)

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“…On the other hand, we reported that knock-down of complexin II decreases exocytotic release in mast cells. 10) Complexin I binds to SNARE complex in nerve terminal and make it stable, 23) therefore it is reasonable that SNARE complex become unstable in mast cells when complexin II is knocked down. We think that synaptotagmin 2 fails to bind to unstable SNARE complex, resulting in decrease of Ca 2+ sensitivity and exocytotic release.…”

Section: Discussionmentioning

confidence: 99%

“…10) Complexin II also interacts with SNARE complexes containing SNAP-23, syntaxin-3, and VAMP-2 or -8 in mast cells. 20) We examined whether these SNARE proteins induce membrane fusion between liposomes.…”

Section: Fusion Degree Between Mast Cell Snare-containingmentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9] SNARE-binding proteins also regulate exocytotic release in mast cells. 9,10) Syntaxin-3, -4 and synaptosomal-associated protein 23 kDa (SNAP-23) are SNARE proteins on the plasma membrane (t-SNARE) in mast cells. [2][3][4] Vesicle associated membrane protein (VAMP)-2, -7, and -8 are SNARE proteins on the secretory vesicles membrane (v-SNARE).…”

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confidence: 99%

“…15,16) Complexin II, but not complexin I, is expressed in mast cells, and exocytotic release after antigen stimulation is suppressed in mast cells where complexin II has been knocked down. 10) To elucidate the molecular mechanism of SNARE-dependent exocytosis in mast cells, we examined effects of complexin II on mast cell SNARE-dependent liposomal membrane fusion that is a simple assay system without other factors derived from cells. 11,[17][18][19] …”

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Effect of Complexin II on Membrane Fusion between Liposomes Containing Mast Cell SNARE Proteins

Tadokoro

Hirashima

Utsunomiya‐Tate

2016

Biological & Pharmaceutical Bulletin

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Mast cells are involved in allergic responses and undergo exocytotic release of inflammatory mediators in response to antigen stimulation. Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are involved in this membrane fusion process; some SNARE-binding proteins regulate SNARE-dependent liposome membrane fusion. SNARE-binding protein complexin II is expressed in mast cells, where it positively regulates exocytotic release after antigen stimulation. We found that complexin II suppressed SNARE-dependent membrane fusion between mast cell SNARE-containing liposomes. This inhibitory effect of complexin II was abolished when we used a structurally divergent mutant (R59H) complexin II, where Arg59 is substituted with histidine. These results suggest that complexin II negatively regulates SNARE-dependent exocytotic membrane fusion in mast cells, and this inhibitory effect is dependent upon Arg59.Key words mast cell; exocytosis; membrane fusion; soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE); degranulation Mast cells are involved in allergic reactions. Cross-linking of FcεRI, the high-affinity receptor for the Fc region of immunoglobulin E, by multivalent antigens increases intracellular Ca 2+ concentration, causing exocytotic inflammatory mediator release from mast cells. 1) Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are involved in this process. 2-9) SNARE-binding proteins also regulate exocytotic release in mast cells. 9,10) Syntaxin-3, -4 and synaptosomal-associated protein 23 kDa (SNAP-23) are SNARE proteins on the plasma membrane (t-SNARE) in mast cells. 2-4) Vesicle associated membrane protein (VAMP)-2, -7, and -8 are SNARE proteins on the secretory vesicles membrane (v-SNARE). 3,4) These t-SNARE and v-SNARE interact with each other and form SNARE complex which induce exocytotic release. [4][5][6] Final stage of exocytosis is membrane fusion process between secretory granule membrane and plasma membrane. SNAP-23/syntaxin-3 or SANP23/syntaxin-4 incorporated liposomes fuse with VAMP-8 but not VAMP-7 incorporated liposomes. 11)Complexins possess an α-helix in their central region that binds to and regulates SNAREs. 12) Complexins I and II are expressed in neuronal cells and may be involved in neurotransmitter release. 13,14) Complexin affects neuronal SNARE-mediated membrane fusion between liposomes. 15,16) Complexin II, but not complexin I, is expressed in mast cells, and exocytotic release after antigen stimulation is suppressed in mast cells where complexin II has been knocked down. 10) To elucidate the molecular mechanism of SNARE-dependent exocytosis in mast cells, we examined effects of complexin II on mast cell SNARE-dependent liposomal membrane fusion that is a simple assay system without other factors derived from cells. 11,[17][18][19] MATERIALS AND METHODS Protein Expression and PurificationFull-length rat syntaxin-3, SNAP-23, VAMP-2 or -8, and complexin II were expressed in Escherichia coli (E....

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Section: Discussionmentioning

confidence: 99%

Section: Fusion Degree Between Mast Cell Snare-containingmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of Complexin II on Membrane Fusion between Liposomes Containing Mast Cell SNARE Proteins

Tadokoro

Hirashima

Utsunomiya‐Tate

2016

Biological & Pharmaceutical Bulletin

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“…Upon elevation of intracellular Ca 2ϩ , complexin 1 was proposed to be displaced from the SNARE complex by synaptotagmin 1, in turn allowing the final stages of neurotransmitter release to commence (7). More recent studies have shown that in addition to this clamping activity, complexin 1 also directly facilitates the final stages of exocytosis (9,10).…”

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confidence: 99%

Complexin 2 Modulates Vesicle-associated Membrane Protein (VAMP) 2-regulated Zymogen Granule Exocytosis in Pancreatic Acini

Falkowski

Thomas

Groblewski

2010

Journal of Biological Chemistry

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Complexins are soluble proteins that regulate the activity of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes necessary for vesicle fusion. Neuronal specific complexin 1 has inhibitory and stimulatory effects on exocytosis by clamping trans-SNARE complexes in a prefusion state and promoting conformational changes to facilitate membrane fusion following cell stimulation. Complexins are unable to bind to monomeric SNARE proteins but bind with high affinity to ternary SNARE complexes and with lower affinity to target SNARE complexes. Far less is understood about complexin function outside the nervous system. Pancreatic acini express the complexin 2 isoform by RT-PCR and immunoblotting. Immunofluorescence microscopy revealed complexin 2 localized along the apical plasma membrane consistent with a role in secretion. Accordingly, complexin 2 was found to interact with vesicle-associated membrane protein (VAMP) 2, syntaxins 3 and 4, but not with VAMP 8 or syntaxin 2. Introduction of recombinant complexin 2 into permeabilized acini inhibited Ca 2؉ -stimulated secretion in a concentration-dependent manner with a maximal inhibition of nearly 50%. Mutations of the central ␣-helical domain reduced complexin 2 SNARE binding and concurrently abolished its inhibitory activity. Surprisingly, mutation of arginine 59 to histidine within the central ␣-helical domain did not alter SNARE binding and moreover, augmented Ca 2؉ -stimulated secretion by 130% of control. Consistent with biochemical studies, complexin 2 colocalized with VAMP 2 along the apical plasma membrane following cholecystokinin-8 stimulation. These data demonstrate a functional role for complexin 2 outside the nervous system and indicate that it participates in the Ca 2؉ -sensitive regulatory pathway for zymogen granule exocytosis.Complexin 1, originally identified as synaphin, is a small cytosolic protein that associates with soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes, which are essential to drive membrane fusion during neurotransmitter exocytosis (1, 2). Although complexin 1 is expressed exclusively in neurons, complexin 2 appears to be ubiquitously expressed and presumably functions in other secretory cell systems. Complexins 1 and 2 are highly homologous, each containing 134 amino acids that are 86% identical (3). Moreover, rat, mouse, and human complexin 2 proteins are 100% identical, although the nucleotide sequences of their mRNAs are considerably different (4). Recently, two other isoforms, complexins 3 and 4, were identified; however, evidence of their specific function is unclear. Complexin 3 is expressed strongly in retina and certain regions of the brain including the hippocampus and thalamus, whereas complexin 4 is only expressed in retina (5).In neurons, the SNARE complex is a four-helical bundle composed of vesicle associated membrane protein (VAMP) 2 2, and the target SNAREs (t-SNAREs), syntaxin 1 and SNAP 25, located on the plasma membrane (6). Complexin 1 was orig...

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Evolutionary origin of synapses and neurons – Bridging the gap

Burkhardt

Sprecher

2017

BioEssays

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The evolutionary origin of synapses and neurons is an enigmatic subject that inspires much debate. Non-bilaterian metazoans, both with and without neurons and their closest relatives already contain many components of the molecular toolkits for synapse functions. The origin of these components and their assembly into ancient synaptic signaling machineries are particularly important in light of recent findings on the phylogeny of non-bilaterian metazoans. The evolution of synapses and neurons are often discussed only from a metazoan perspective leaving a considerable gap in our understanding. By taking an integrative approach we highlight the need to consider different, but extremely relevant phyla and to include the closest unicellular relatives of metazoans, the ichthyosporeans, filastereans and choanoflagellates, to fully understand the evolutionary origin of synapses and neurons. This approach allows for a detailed understanding of when and how the first pre-and postsynaptic signaling machineries evolved. Keywords:.e volution; neuron; origin; protein-protein interactions; synapse Exciting times for the debate about the evolutionary origin of neurons "Ideas about invertebrate phylogeny are often presented as though they were widely agreedupon theories or, worse yet, as though alternative ideas did not even exist"Nervous systems within the metazoan kingdom are surprisingly diverse both in cell number and functional complexity. The nervous system of the nematode Caenorhabditis elegans consists of only 302 neurons while the brains of mammals, including humans, are comprised of multiple billions of neural cells. But also the diversity of neuron types within the nervous system is striking making "neuron" likely the most diverse cell type existing [2][3]. Distinct neuron types are defined for instance by the neurotransmitter or neuropeptide they use, their morphological and anatomical properties, whether they receive sensory input or control motor output but also by their physiological and membrane properties. However, defining what makes all neurons distinct from other cell types at a molecular basis remains challenging, since many features that are essential for a neuron to function can also be found in other somatic cells. One key characteristic that almost all neurons have in common is that they are able to communicate to each other (or to non-neuronal cells) via specialized synaptic connections [3][4]. Thus, the emergence of intercellular communication via pre-and postsynaptic molecular machineries may be considered a turning point in evolution allowing cells to transmit and integrate information.Yet, neurons are not absolutely essential for all metazoan life since entire lineages of non-bilaterian metazoans appear to completely lack neurons. Conversely, many molecular components of neurons, such as synaptic proteins, evolved before neurons were present [5]. This raises fundamental questions regarding the evolutionary origin of the nervous

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Complexin II facilitates exocytotic release in mast cells by enhancing Ca2+ sensitivity of the fusion process

Cited by 61 publications

References 45 publications

Effect of Complexin II on Membrane Fusion between Liposomes Containing Mast Cell SNARE Proteins

Effect of Complexin II on Membrane Fusion between Liposomes Containing Mast Cell SNARE Proteins

Complexin 2 Modulates Vesicle-associated Membrane Protein (VAMP) 2-regulated Zymogen Granule Exocytosis in Pancreatic Acini

Evolutionary origin of synapses and neurons – Bridging the gap

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