scholarly journals Local regulation of extracellular vesicle traffic by the synaptic endocytic machinery

2021 ◽  
Author(s):  
Cassandra R Blanchette ◽  
Amy L Scalera ◽  
Kathryn P Harris ◽  
Zechuan Zhao ◽  
Kate Koles ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Extracellular Vesicle ◽  
Retrograde Axonal Transport ◽  
Intercellular Signaling ◽  
Synaptic Growth ◽  
Local Regulation ◽  
Vesicle Traffic ◽  
Vesicle Recycling ◽  
Retromer Complex ◽  
Endocytic Machinery

Neuronal extracellular vesicles (EVs) carry cargoes that are important in intercellular signaling and disease, but how and where cargoes are sorted into EVs remains unclear. Here, we identified a new role for canonical clathrin-mediated endocytic machinery in controlling EV cargo traffic in Drosophila neurons. Endocytic mutants, including nervous wreck (nwk), Shibire/Dynamin, and AP-2, exhibit local depletion of multiple cargoes in presynaptic EV donor terminals as well as in EVs. Accordingly, nwk mutants phenocopy synaptic plasticity defects associated with loss of the EV cargo Synaptotagmin-4, and suppress lethality upon overexpression of the EV cargo Amyloid Precursor Protein. These EV defects are genetically separable from canonical functions of endocytic proteins in synaptic vesicle recycling and synaptic growth. Nwk opposes the endosomal retromer complex to regulate EV cargo levels, and acts upstream of dynactin-mediated retrograde axonal transport. Our data suggest a novel molecular mechanism that protects EV cargoes from local depletion at synapses.

scholarly journals Opposing functions for retromer and Rab11 in extracellular vesicle traffic at presynaptic terminals

2021 ◽  
Vol 220 (8) ◽  
Author(s):  
Rylie B. Walsh ◽  
Erica C. Dresselhaus ◽  
Agata N. Becalska ◽  
Matthew J. Zunitch ◽  
Cassandra R. Blanchette ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Intercellular Communication ◽  
Neurological Disease ◽  
Extracellular Vesicle ◽  
Membrane Recycling ◽  
Presynaptic Terminals ◽  
Vesicle Traffic ◽  
Retromer Complex ◽  
Shed Light ◽  
Competing Pathways

Neuronal extracellular vesicles (EVs) play important roles in intercellular communication and pathogenic protein propagation in neurological disease. However, it remains unclear how cargoes are selectively packaged into neuronal EVs. Here, we show that loss of the endosomal retromer complex leads to accumulation of EV cargoes including amyloid precursor protein (APP), synaptotagmin-4 (Syt4), and neuroglian (Nrg) at Drosophila motor neuron presynaptic terminals, resulting in increased release of these cargoes in EVs. By systematically exploring known retromer-dependent trafficking mechanisms, we show that EV regulation is separable from several previously identified roles of neuronal retromer. Conversely, mutations in rab11 and rab4, regulators of endosome-plasma membrane recycling, cause reduced EV cargo levels, and rab11 suppresses cargo accumulation in retromer mutants. Thus, EV traffic reflects a balance between Rab4/Rab11 recycling and retromer-dependent removal from EV precursor compartments. Our data shed light on previous studies implicating Rab11 and retromer in competing pathways in Alzheimer’s disease, and suggest that misregulated EV traffic may be an underlying defect.

scholarly journals Nervous Wreck Interacts with Thickveins and the Endocytic Machinery to Attenuate Retrograde BMP Signaling during Synaptic Growth

Neuron ◽  
2008 ◽  
Vol 58 (4) ◽  
pp. 507-518 ◽  
Author(s):  
Kate M. O'Connor-Giles ◽  
Ling Ling Ho ◽  
Barry Ganetzky
Keyword(s):  
Bmp Signaling ◽  
Synaptic Growth ◽  
Endocytic Machinery

scholarly journals Postsynaptic regulation of synaptic plasticity by synaptotagmin 4 requires both C2 domains

2009 ◽  
Vol 187 (2) ◽  
pp. 295-310 ◽  
Author(s):  
Cynthia F. Barber ◽  
Ramon A. Jorquera ◽  
Jan E. Melom ◽  
J. Troy Littleton
Keyword(s):  
Synaptic Plasticity ◽  
Messenger Rna ◽  
Molecular Mechanisms ◽  
Neuromuscular Junctions ◽  
Vesicle Fusion ◽  
Synaptic Growth ◽  
Synaptotagmin 1 ◽  
Presynaptic Vesicle ◽  
Activity Dependent

Ca2+ influx into synaptic compartments during activity is a key mediator of neuronal plasticity. Although the role of presynaptic Ca2+ in triggering vesicle fusion though the Ca2+ sensor synaptotagmin 1 (Syt 1) is established, molecular mechanisms that underlie responses to postsynaptic Ca2+ influx remain unclear. In this study, we demonstrate that fusion-competent Syt 4 vesicles localize postsynaptically at both neuromuscular junctions (NMJs) and central nervous system synapses in Drosophila melanogaster. Syt 4 messenger RNA and protein expression are strongly regulated by neuronal activity, whereas altered levels of postsynaptic Syt 4 modify synaptic growth and presynaptic release properties. Syt 4 is required for known forms of activity-dependent structural plasticity at NMJs. Synaptic proliferation and retrograde signaling mediated by Syt 4 requires functional C2A and C2B Ca2+–binding sites, as well as serine 284, an evolutionarily conserved substitution for a key Ca2+-binding aspartic acid found in other synaptotagmins. These data suggest that Syt 4 regulates activity-dependent release of postsynaptic retrograde signals that promote synaptic plasticity, similar to the role of Syt 1 as a Ca2+ sensor for presynaptic vesicle fusion.

scholarly journals Opposing functions for retromer and Rab11 in extracellular vesicle cargo traffic at presynaptic terminals

2019 ◽  
Author(s):  
Rylie B. Walsh ◽  
Agata N. Becalska ◽  
Matthew J. Zunitch ◽  
Tania Lemos ◽  
Erica C. Dresselhaus ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Motor Neuron ◽  
Intercellular Communication ◽  
Neurological Disease ◽  
Extracellular Vesicle ◽  
Presynaptic Terminals ◽  
Recycling Endosome ◽  
Retromer Complex ◽  
Shed Light ◽  
Competing Pathways

ABSTRACTNeuronal extracellular vesicles (EVs) play important roles in intercellular communication and pathogenic protein propagation in neurological disease. However, it remains unclear how cargoes are selectively packaged into neuronal EVs. Here, we show that loss of the endosomal retromer complex leads to accumulation of EV cargoes Amyloid Precursor Protein (APP) and Synaptotagmin-4 (Syt4) at Drosophila motor neuron presynaptic terminals, resulting in increased release of these cargoes in EVs. By systematically exploring known retromer-dependent trafficking mechanisms, we show that EV regulation is separable from several previously identified roles of neuronal retromer, and depends on the ESCPE-1 complex. Conversely, loss of the recycling endosome regulator rab11 leads to reduced EV cargo levels, and suppresses cargo accumulation in retromer mutants. Thus, EV traffic reflects a balance between Rab11-mediated loading and retromer-dependent removal from EV precursor compartments. Our data shed light on previous studies implicating Rab11 and retromer in competing pathways in Alzheimer’s Disease, and suggest that misregulated EV traffic may be an underlying defect.

scholarly journals RAB-6.2 and the retromer regulate glutamate receptor recycling through a retrograde pathway

2012 ◽  
Vol 196 (1) ◽  
pp. 85-101 ◽  
Author(s):  
Donglei Zhang ◽  
Nora R. Isack ◽  
Doreen R. Glodowski ◽  
Jie Liu ◽  
Carlos Chih-Hsiung Chen ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Membrane Trafficking ◽  
Retrograde Transport ◽  
Receptor Recycling ◽  
Transport Pathway ◽  
Retromer Complex ◽  
Domain Protein ◽  
Phosphotyrosine Binding Domain

Regulated membrane trafficking of AMPA-type glutamate receptors (AMPARs) is a key mechanism underlying synaptic plasticity, yet the pathways used by AMPARs are not well understood. In this paper, we show that the AMPAR subunit GLR-1 in Caenorhabditis elegans utilizes the retrograde transport pathway to regulate AMPAR synaptic abundance. Mutants for rab-6.2, the retromer genes vps-35 and snx-1, and rme-8 failed to recycle GLR-1 receptors, resulting in GLR-1 turnover and behavioral defects indicative of diminished GLR-1 function. In contrast, expression of constitutively active RAB-6.2 drove the retrograde transport of GLR-1 from dendrites back to cell body Golgi. We also find that activated RAB-6.2 bound to and colocalized with the PDZ/phosphotyrosine binding domain protein LIN-10. RAB-6.2 recruited LIN-10. Moreover, the regulation of GLR-1 transport by RAB-6.2 required LIN-10 activity. Our results demonstrate a novel role for RAB-6.2, its effector LIN-10, and the retromer complex in maintaining synaptic strength by recycling AMPARs along the retrograde transport pathway.

An Analysis of Synaptic Normalization in a General Class of Hebbian Models

2003 ◽  
Vol 15 (4) ◽  
pp. 937-963 ◽  
Author(s):  
Terry Elliott
Keyword(s):  
Fixed Point ◽  
Synaptic Plasticity ◽  
Electrical Activity ◽  
General Class ◽  
Competitive Dynamics ◽  
Synaptic Growth ◽  
Activity Dependent ◽  
Multiplicative Normalization

In standard Hebbian models of developmental synaptic plasticity, synaptic normalization must be introduced in order to constrain synaptic growth and ensure the presence of activity-dependent, competitive dynamics. In such models, multiplicative normalization cannot segregate afferents whose patterns of electrical activity are positively correlated, while subtractive normalization can. It is now widely believed that multiplicative normalization cannot segregate positively correlated afferents in any Hebbian model. However, we recently provided a counterexample to this belief by demonstrating that our own neurotrophic model of synaptic plasticity, which can segregate positively correlated afferents, can be reformulated as a nonlinear Hebbian model with competition implemented through multiplicative normalization. We now perform an analysis of a general class of Hebbian models under general forms of synaptic normalization. In particular, we extract conditions on the forms of these rules that guarantee that such models possess a fixed-point structure permitting the segregation of all but perfectly correlated afferents. We find that the failure of multiplicative normalization to segregate positively correlated afferents in a standard Hebbian model is quite atypical.

scholarly journals The postsynaptic t-SNARE Syntaxin 4 controls traffic of Neuroligin 1 and Synaptotagmin 4 to regulate retrograde signaling

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Kathryn P Harris ◽  
Yao V Zhang ◽  
Zachary D Piccioli ◽  
Norbert Perrimon ◽  
J Troy Littleton
Keyword(s):  
Synaptic Plasticity ◽  
Neuromuscular Junctions ◽  
Genetic Interaction ◽  
Retrograde Signaling ◽  
Synaptic Development ◽  
Synaptic Growth ◽  
Adhesion Protein ◽  
Neuronal Stimulation ◽  
Syntaxin 4 ◽  
Activity Dependent

Postsynaptic cells can induce synaptic plasticity through the release of activity-dependent retrograde signals. We previously described a Ca2+-dependent retrograde signaling pathway mediated by postsynaptic Synaptotagmin 4 (Syt4). To identify proteins involved in postsynaptic exocytosis, we conducted a screen for candidates that disrupted trafficking of a pHluorin-tagged Syt4 at Drosophila neuromuscular junctions (NMJs). Here we characterize one candidate, the postsynaptic t-SNARE Syntaxin 4 (Syx4). Analysis of Syx4 mutants reveals that Syx4 mediates retrograde signaling, modulating the membrane levels of Syt4 and the transsynaptic adhesion protein Neuroligin 1 (Nlg1). Syx4-dependent trafficking regulates synaptic development, including controlling synaptic bouton number and the ability to bud new varicosities in response to acute neuronal stimulation. Genetic interaction experiments demonstrate Syx4, Syt4, and Nlg1 regulate synaptic growth and plasticity through both shared and parallel signaling pathways. Our findings suggest a conserved postsynaptic SNARE machinery controls multiple aspects of retrograde signaling and cargo trafficking within the postsynaptic compartment.

scholarly journals Antisense oligonucleotide activity in tumour cells is influenced by intracellular LBPA distribution and extracellular vesicle recycling

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alexander N. Kapustin ◽  
Paul Davey ◽  
David Longmire ◽  
Carl Matthews ◽  
Emily Linnane ◽  
...  
Keyword(s):  
Cell Lines ◽  
Antisense Oligonucleotide ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Extracellular Vesicle ◽  
Tumour Cells ◽  
Intracellular Traffic ◽  
Therapeutic Modalities ◽  
Vesicle Recycling ◽  
Lysobisphosphatidic Acid

AbstractNext generation modified antisense oligonucleotides (ASOs) are commercially approved new therapeutic modalities, yet poor productive uptake and endosomal entrapment in tumour cells limit their broad application. Here we compare intracellular traffic of anti KRAS antisense oligonucleotide (AZD4785) in tumour cell lines PC9 and LK2, with good and poor productive uptake, respectively. We find that the majority of AZD4785 is rapidly delivered to CD63+late endosomes (LE) in both cell lines. Importantly, lysobisphosphatidic acid (LBPA) that triggers ASO LE escape is presented in CD63+LE in PC9 but not in LK2 cells. Moreover, both cell lines recycle AZD4785 in extracellular vesicles (EVs); however, AZD4785 quantification by advanced mass spectrometry and proteomic analysis reveals that LK2 recycles more AZD4785 and RNA-binding proteins. Finally, stimulating LBPA intracellular production or blocking EV recycling enhances AZD4785 activity in LK2 but not in PC9 cells thus offering a possible strategy to enhance ASO potency in tumour cells with poor productive uptake of ASOs.

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