scholarly journals Simulation of a sudden drop-off in distal dense core vesicle concentration in Drosophila type II motoneuron terminals

2021 ◽  
Author(s):  
Ivan A Kuznetsov ◽  
Andrey V Kuznetsov
Keyword(s):  
Molecular Motors ◽  
Synaptic Function ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Type Ii ◽  
Dense Core Vesicles ◽  
Sudden Drop

This paper aims to investigate whether the sudden drop in the content of dense core vesicles (DCVs) reported in [J. Tao, D. Bulgari, D.L. Deitcher, E.S. Levitan, Limited distal organelles and synaptic function in extensive monoaminergic innervation, J. Cell. Sci. 130 (2017) 2520-2529] can be explained without modifying the parameters characterizing the ability of distal en passant boutons to capture and accumulate DCVs. We hypothesize that the drop in DCV content in distal boutons is due to an insufficient supply of anterogradely moving DCVs coming from the soma. As anterogradely moving DCVs are captured (and eventually destroyed) in more proximal boutons on their way to the end of the terminal, the fluxes of anterogradely moving DCVs between the boutons become increasingly smaller, and the most distal boutons are left without DCVs. We tested this hypothesis by modifying the flux of DCVs entering the terminal and found that the number of most distal boutons left unfilled increases if the DCV flux entering the terminal is decreased. The number of anterogradely moving DCVs in the axon can be increased either by the release of a portion of captured DCVs into the anterograde component or by an increase of the anterograde DCV flux into the terminal. This increase could lead to having enough anterogradely moving DCVs such that they could reach the most distal bouton and then turn around by changing molecular motors that propel them. The model suggests that this could result in an increased concentration of resident DCVs in distal boutons beginning with bouton 2. This is because in distal boutons, DCVs have a larger chance to be captured from the transiting state as they pass the boutons moving anterogradely and then again as they pass the same boutons moving retrogradely.

scholarly journals MicroRNA exocytosis by large dense-core vesicle fusion

2016 ◽  
Author(s):  
Alican Gümürdü ◽  
Ramazan Yildiz ◽  
Erden Eren ◽  
Gökhan Karakülah ◽  
Turgay Ünver ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Vesicle Fusion ◽  
Dense Core ◽  
Snare Complex ◽  
Dense Core Vesicle ◽  
Next Generation ◽  
Dense Core Vesicles ◽  
Large Dense Core Vesicles ◽  
Extracellular Mirna ◽  
Generation Sequencing

AbstractNeurotransmitters and peptide hormones are secreted into outside the cell by a vesicle fusion process. Although non-coding RNA (ncRNA) that include microRNA (miRNA) regulates gene expression inside the cell where they are transcribed, extracellular miRNA has been recently discovered outside the cells, proposing that miRNA might be released to participate in cell-to-cell communication. Despite its importance of extracellular miRNA, the molecular mechanisms by which miRNA can be stored in vesicles and released by vesicle fusion remain enigmatic. Using next-generation sequencing, vesicle purification techniques, and synthetic neurotransmission, we observe that large dense-core vesicles (LDCVs) contain a variety of miRNAs including miR-375. Furthermore, miRNA exocytosis is mediated by the SNARE complex and accelerated by Ca2+. Our results suggest that miRNA can be a novel neuromodulator that can be stored in vesicles and released by vesicle fusion together with classical neurotransmitters.One Sentence SummaryUsing next-generation sequencing (NGS) for microRNA (miRNA) and synthetic neurotransmission, we observed that large dense-core vesicles (LDCVs) contain a variety of miRNA together with classical neurotransmitters, and that miRNA can be released by vesicle fusion mediated by SNARE.

scholarly journals Modelling transport and mean age of dense core vesicles in large axonal arbours

2019 ◽  
Vol 475 (2228) ◽  
pp. 20190284
Author(s):  
I. A. Kuznetsov ◽  
A. V. Kuznetsov
Keyword(s):  
Steady State ◽  
Dense Core ◽  
Type Ii ◽  
Dense Core Vesicles ◽  
Density Distributions ◽  
The Mean

A model simulating the transport of dense core vesicles (DCVs) in type II axonal terminals of Drosophila motoneurons has been developed. The morphology of type II terminals is characterized by the large number of en passant boutons. The lack of both scaled-up DCV transport and scaled-down DCV capture in boutons results in a less efficient supply of DCVs to distal boutons. Furthermore, the large number of boutons that DCVs pass as they move anterogradely until they reach the most distal bouton may lead to the capture of a majority of DCVs before they turn around in the most distal bouton to move in the retrograde direction. This may lead to a reduced retrograde flux of DCVs and a lack of DCV circulation in type II terminals. The developed model simulates DCV concentrations in boutons, DCV fluxes between the boutons, age density distributions of DCVs and the mean age of DCVs in various boutons. Unlike published experimental observations, our model predicts DCV circulation in type II terminals after these terminals are filled to saturation. This disagreement is likely because experimentally observed terminals were not at steady state, but rather were accumulating DCVs for later release. Our estimates show that the number of DCVs in the transiting state is much smaller than that in the resident state. DCVs travelling in the axon, rather than DCVs transiting in the terminal, may provide a reserve of DCVs for replenishing boutons after a release. The techniques for modelling transport of DCVs developed in our paper can be used to model the transport of other organelles in axons.

scholarly journals The Slp4-a Linker Domain Controls Exocytosis through Interaction with Munc18-1·Syntaxin-1a Complex

2006 ◽  
Vol 17 (5) ◽  
pp. 2101-2112 ◽  
Author(s):  
Takashi Tsuboi ◽  
Mitsunori Fukuda
Keyword(s):  
Plasma Membrane ◽  
Specific Interaction ◽  
Inhibitory Effect ◽  
Neuroendocrine Cells ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Dense Core Vesicles ◽  
Syntaxin 1A ◽  
Vesicle Exocytosis ◽  
Linker Domain

Synaptotagmin-like protein 4-a (Slp4-a)/granuphilin-a is specifically localized on dense-core vesicles in certain neuroendocrine cells and negatively controls dense-core vesicle exocytosis through specific interaction with Rab27A. However, the precise molecular mechanism of its inhibitory effect on exocytosis has never been elucidated and is still a matter of controversy. Here we show by deletion and chimeric analyses that the linker domain of Slp4-a interacts with the Munc18-1·syntaxin-1a complex by directly binding to Munc18-1 and that this interaction promotes docking of dense-core vesicles to the plasma membrane in PC12 cells. Despite increasing the number of plasma membrane docked vesicles, expression of Slp4-a strongly inhibited high-KCl–induced dense-core vesicle exocytosis. The inhibitory effect by Slp4-a is absolutely dependent on the linker domain of Slp4-a, because substitution of the linker domain of Slp4-a by that of Slp5 (the closest isoform of Slp4-a that cannot bind the Munc18-1·syntaxin-1a complex) completely abrogated the inhibitory effect. Our findings reveal a novel docking machinery for dense-core vesicle exocytosis: Slp4-a simultaneously interacts with Rab27A and Munc18-1 on the dense-core vesicle and with syntaxin-1a in the plasma membrane.

scholarly journals Rab2 drives axonal transport of dense core vesicles and lysosomal organelles

2020 ◽  
Author(s):  
Viktor K. Lund ◽  
Matthew D. Lycas ◽  
Anders Schack ◽  
Rita C. Andersen ◽  
Ulrik Gether ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Long Range ◽  
Molecular Motors ◽  
Critical Role ◽  
Model System ◽  
Small Gtpase ◽  
Dense Core ◽  
Fast Axonal Transport ◽  
Dense Core Vesicles ◽  
Motility Factor

SUMMARYLong range fast axonal transport of neuropeptide-containing dense core vesicles (DCVs), endolysosomal organelles and presynaptic components is critical for maintaining the functionality of neurons. How the transport of DCVs is orchestrated remains an important unresolved question. The small GTPase Rab2 has previously been shown to mediate DCV biogenesis and endosome-lysosome fusion. Here we use the Drosophila model system to demonstrate that Rab2 also plays a critical role in bidirectional axonal transport of DCVs, endosomes and lysosomal organelles, most likely by controlling molecular motors. We further show that the lysosomal motility factor Arl8 is required as well for axonal transport of DCVs, but unlike Rab2 is also critical for DCV exit from cell bodies into axons. Our results uncover the mechanisms responsible for axonal transport of DCVs and reveal surprising parallels between the regulation of DCVs and lysosomal motility.

scholarly journals Image-guided MALDI mass spectrometry for high-throughput single-organelle characterization

2021 ◽  
Vol 18 (10) ◽  
pp. 1233-1238 ◽  
Author(s):  
Daniel C. Castro ◽  
Yuxuan Richard Xie ◽  
Stanislav S. Rubakhin ◽  
Elena V. Romanova ◽  
Jonathan V. Sweedler
Keyword(s):  
Mass Spectrometry ◽  
High Throughput ◽  
Mass Range ◽  
Maldi Mass Spectrometry ◽  
Proteolytic Processing ◽  
Dense Core ◽  
Exocrine Function ◽  
Dense Core Vesicle ◽  
Dense Core Vesicles ◽  
Image Guided

AbstractPeptidergic dense-core vesicles are involved in packaging and releasing neuropeptides and peptide hormones—critical processes underlying brain, endocrine and exocrine function. Yet, the heterogeneity within these organelles, even for morphologically defined vesicle types, is not well characterized because of their small volumes. We present image-guided, high-throughput mass spectrometry-based protocols to chemically profile large populations of both dense-core vesicles and lucent vesicles for their lipid and peptide contents, allowing observation of the chemical heterogeneity within and between these two vesicle populations. The proteolytic processing products of four prohormones are observed within the dense-core vesicles, and the mass spectral features corresponding to the specific peptide products suggest three distinct dense-core vesicle populations. Notable differences in the lipid mass range are observed between the dense-core and lucent vesicles. These single-organelle mass spectrometry approaches are adaptable to characterize a range of subcellular structures.

scholarly journals Atg16L1, an essential factor for canonical autophagy, participates in hormone secretion from PC12 cells independently of autophagic activity

2012 ◽  
Vol 23 (16) ◽  
pp. 3193-3202 ◽  
Author(s):  
Koutaro Ishibashi ◽  
Takefumi Uemura ◽  
Satoshi Waguri ◽  
Mitsunori Fukuda
Keyword(s):  
Pc12 Cells ◽  
Secretory Pathway ◽  
Biological Activities ◽  
Hormone Secretion ◽  
Cell Types ◽  
Small Gtpase ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Dense Core Vesicles ◽  
Autophagic Activity

Autophagy is a bulk degradation system in all eukaryotic cells and regulates a variety of biological activities in higher eukaryotes. Recently involvement of autophagy in the regulation of the secretory pathway has also been reported, but the molecular mechanism linking autophagy with the secretory pathway remains largely unknown. Here we show that Atg16L1, an essential protein for canonical autophagy, is localized on hormone-containing dense-core vesicles in neuroendocrine PC12 cells and that knockdown of Atg16L1 causes a dramatic reduction in the level of hormone secretion independently of autophagic activity. We also find that Atg16L1 interacts with the small GTPase Rab33A and that this interaction is required for the dense-core vesicle localization of Atg16L1 in PC12 cells. Our findings indicate that Atg16L1 regulates not only autophagy in all cell types, but also secretion from dense-core vesicles, presumably by acting as a Rab33A effector, in particular cell types.

scholarly journals EIPR1 controls dense-core vesicle cargo retention and EARP complex localization in insulin-secreting cells

2020 ◽  
Vol 31 (1) ◽  
pp. 59-79 ◽  
Author(s):  
Irini Topalidou ◽  
Jérôme Cattin-Ortolá ◽  
Blake Hummer ◽  
Cedric S. Asensio ◽  
Michael Ailion
Keyword(s):  
Insulin Secretion ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Secretory Vesicles ◽  
Dense Core Vesicles ◽  
Interacting Protein ◽  
Insulin Secreting Cells

Dense-core vesicles (DCVs) are secretory vesicles that package and secrete cargoes like insulin, but how cargo is sorted to DCVs is poorly understood. Here, it is shown that the EARP complex-interacting protein EIPR1 controls insulin secretion and localization of DCV cargo in insulin-secreting cells.

scholarly journals How old are dense-core vesicles residing in en passant boutons: simulation of the mean age of dense-core vesicles in axonal arbours accounting for resident and transiting vesicle populations

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200454
Author(s):  
Ivan A. Kuznetsov ◽  
Andrey V. Kuznetsov
Keyword(s):  
Dopaminergic Neurons ◽  
Axon Terminal ◽  
Axonal Degeneration ◽  
Dense Core ◽  
Age Difference ◽  
Type Ii ◽  
Dense Core Vesicles ◽  
Axon Terminals ◽  
The Mean ◽  
Dying Back

In neurons, neuropeptides are synthesized in the soma and are then transported along the axon in dense-core vesicles (DCVs). DCVs are captured in varicosities located along the axon terminal called en passant boutons, which are active terminal sites that accumulate and release neurotransmitters. Recently developed experimental techniques allow for the estimation of the age of DCVs in various locations in the axon terminal. Accurate simulation of the mean age of DCVs in boutons requires the development of a model that would account for resident, transiting-anterograde and transiting-retrograde DCV populations. In this paper, such a model is developed. The model is applied to simulating DCV transport in Drosophila type II motoneurons. The model simulates DCV transport and capture in the axon terminals and makes it possible to predict the age density distribution of DCVs in en passant boutons as well as DCV mean age in boutons. The predicted prevalence of older organelles in distal boutons may explain the ‘dying back’ pattern of axonal degeneration observed in dopaminergic neurons in Parkinson's disease. The predicted difference of two hours between the age of older DCVs residing in distal boutons and the age of younger DCVs residing in proximal boutons is consistent with an approximate estimate of age difference deduced from experimental observations. The age density of resident DCVs is found to be bimodal, which is because DCVs are captured from two transiting states: the anterograde transiting state that contains younger DCVs and the retrograde transiting state that contains older DCVs.

scholarly journals Dense-core vesicle proteins IA-2 and IA-2β affect renin synthesis and secretion through the β-adrenergic pathway

2009 ◽  
Vol 296 (2) ◽  
pp. F382-F389 ◽  
Author(s):  
Soo Mi Kim ◽  
Franziska Theilig ◽  
Yan Qin ◽  
Tao Cai ◽  
Diane Mizel ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Salt Intake ◽  
Plasma Renin ◽  
Dense Core ◽  
Dense Core Vesicle ◽  
Mrna Levels ◽  
Wild Type ◽  
Dense Core Vesicles ◽  
Renin Synthesis ◽  
Renin Mrna

IA-2 and IA-2β, major autoantigens in type 1 diabetes, are transmembrane proteins in dense-core vesicles, and their expression influences the secretion of hormones and neurotransmitters. The present experiments were performed to examine whether IA-2 and IA-2β modulate the release of renin from dense-core vesicles of juxtaglomerular granular cells in the kidney. Plasma renin concentration (PRC; ng angiotensin I·ml−1·h−1) was significantly reduced in mice with null mutations in IA-2, IA-2β, or both IA-2 and IA-2β compared with wild-type mice (876 ± 113, 962 ± 130, and 596 ± 82 vs. 1,367 ± 93; P < 0.01, P < 0.02, and P < 0.001). Renin mRNA levels were reduced to 26.4 ± 5.1, 39 ± 5.4, and 35.3 ± 5.5% of wild-type in IA-2−/−, IA-2β−/−, and IA-2/IA-2β−/− mice. Plasma aldosterone levels were not significantly different among genotypes. The regulation of PRC by furosemide and salt intake, and of aldosterone by salt intake, was maintained in all genotypes. IA-2 and IA-2β expression did not colocalize with renin but showed overlapping immunoreactivity with tyrosine hydroxylase. While propranolol reduced PRC in wild-type mice, it had no effect on PRC in IA-2/ IA-2β−/− mice. Renal tyrosine hydroxylase mRNA and immunoreactivity were reduced in IA-2/IA-2β−/− mice as was the urinary excretion of catecholamines. We conclude that IA-2 and IA-2β are required to maintain normal levels of renin expression and renin release, most likely by permitting normal rates of catecholamine release from sympathetic nerve terminals.

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