Postsynaptic Neuroligin-1 Mediates Presynaptic Endocytosis During Neuronal Activity

Fast, high-fidelity neurotransmission and synaptic efficacy requires tightly regulated coordination of pre- and postsynaptic compartments and alignment of presynaptic release sites with postsynaptic receptor nanodomains. Neuroligin-1 (Nlgn1) is a postsynaptic cell-adhesion protein exclusively localised to excitatory synapses that is crucial for coordinating the transsynaptic alignment of presynaptic release sites with postsynaptic AMPA receptors as well as postsynaptic transmission and plasticity. However, little is understood about whether the postsynaptic machinery can mediate the molecular architecture and activity of the presynaptic nerve terminal, and thus it remains unclear whether there are presynaptic contributions to Nlgn1-dependent control of signalling and plasticity. Here, we employed a presynaptic reporter of neurotransmitter release and synaptic vesicle dynamics, synaptophysin-pHluorin (sypHy), to directly assess the presynaptic impact of loss of Nlgn1. We show that lack of Nlgn1 had no effect on the size of the readily releasable or entire recycling pool of synaptic vesicles, nor did it impact exocytosis. However, we observed significant changes in the retrieval of synaptic vesicles by compensatory endocytosis, specifically during activity. Our data extends growing evidence that synaptic adhesion molecules critical for forming transsynaptic scaffolds are also important for regulating activity-induced endocytosis at the presynapse.

Download Full-text

Postsynaptic neuroligin-1 mediates presynaptic endocytosis during neuronal activity

10.1101/2021.07.20.453031 ◽

2021 ◽

Author(s):

Jiaqi Keith Luo ◽

Holly Melland ◽

Jess Nithianantharajah ◽

Sarah L Gordon

Keyword(s):

Ampa Receptors ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

High Fidelity ◽

Excitatory Synapses ◽

Synaptic Efficacy ◽

Molecular Architecture ◽

Adhesion Protein ◽

Presynaptic Nerve Terminal ◽

Presynaptic Release

Fast, high-fidelity neurotransmission and synaptic efficacy requires tightly regulated coordination of pre- and postsynaptic compartments and alignment of presynaptic release sites with postsynaptic receptor nanodomains. Neuroligin-1 (Nlgn-1) is a postsynaptic cell-adhesion protein exclusively localised to excitatory synapses that is crucial for coordinating the transsynaptic alignment of presynaptic release sites with postsynaptic AMPA receptors as well as postsynaptic transmission and plasticity. However, little is understood about whether the postsynaptic machinery can mediate the molecular architecture and activity of the presynaptic nerve terminal, and thus it remains unclear whether there are presynaptic contributions to Nlgn1-dependent control of signalling and plasticity. Here, we employed a presynaptic reporter of neurotransmitter release and synaptic vesicle dynamics, synaptophysin-pHluorin (sypHy), to directly assess the presynaptic impact of loss of Nlgn1. We show that lack of Nlgn1 had no effect on the size of the readily releasable or entire recycling pool of synaptic vesicles, nor did it impact exocytosis. However, we observed significant changes in the retrieval of synaptic vesicles by compensatory endocytosis, specifically during activity. Our data extends growing evidence that synaptic adhesion molecules critical for forming transsynaptic scaffolds are also important for regulating activity-induced endocytosis at the presynapse.

Download Full-text

Calcium dependence of neurotransmitter release at a high fidelity synapse

eLife ◽

10.7554/elife.70408 ◽

2021 ◽

Vol 10 ◽

Author(s):

Abdelmoneim Eshra ◽

Hartmut Schmidt ◽

Jens Eilers ◽

Stefan Hallermann

Keyword(s):

High Frequency ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

Mossy Fiber ◽

High Fidelity ◽

Technical Challenge ◽

Fundamental Parameters ◽

High Affinity ◽

Vesicle Pools ◽

Intracellular Ca

The Ca2+-dependence of the priming, fusion, and replenishment of synaptic vesicles are fundamental parameters controlling neurotransmitter release and synaptic plasticity. Despite intense efforts, these important steps in the synaptic vesicles’ cycle remain poorly understood due to the technical challenge in disentangling vesicle priming, fusion, and replenishment. Here, we investigated the Ca2+-sensitivity of these steps at mossy fiber synapses in the rodent cerebellum, which are characterized by fast vesicle replenishment mediating high-frequency signaling. We found that the basal free Ca2+ concentration (<200 nM) critically controls action potential-evoked release, indicating a high-affinity Ca2+ sensor for vesicle priming. Ca2+ uncaging experiments revealed a surprisingly shallow and non-saturating relationship between release rate and intracellular Ca2+ concentration up to 50 μM. The rate of vesicle replenishment during sustained elevated intracellular Ca2+ concentration exhibited little Ca2+-dependence. Finally, quantitative mechanistic release schemes with five Ca2+ binding steps incorporating rapid vesicle replenishment via parallel or sequential vesicle pools could explain our data. We thus show that co-existing high- and low-affinity Ca2+ sensors mediate priming, fusion, and replenishment of synaptic vesicles at a high-fidelity synapse.

Download Full-text

Neurotransmitter Secretion along Growing Nerve Processes: Comparison with Synaptic Vesicle Exocytosis

The Journal of Cell Biology ◽

10.1083/jcb.144.3.507 ◽

1999 ◽

Vol 144 (3) ◽

pp. 507-518 ◽

Cited By ~ 67

Author(s):

Stanislav Zakharenko ◽

Sunghoe Chang ◽

Michael O'Donoghue ◽

Sergey V. Popov

Keyword(s):

Nerve Terminal ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

High Frequency Stimulation ◽

Spinal Cord Neurons ◽

Presynaptic Nerve Terminal ◽

Neurotransmitter Secretion ◽

Synaptic Vesicle Exocytosis ◽

Vesicle Exocytosis ◽

Membrane Components

In mature neurons, synaptic vesicles continuously recycle within the presynaptic nerve terminal. In developing axons which are free of contact with a postsynaptic target, constitutive membrane recycling is not localized to the nerve terminal; instead, plasma membrane components undergo cycles of exoendocytosis throughout the whole axonal surface (Matteoli et al., 1992; Kraszewski et al., 1995). Moreover, in growing Xenopus spinal cord neurons in culture, acetylcholine (ACh) is spontaneously secreted in the quantal fashion along the axonal shaft (Evers et al., 1989; Antonov et al., 1998). Here we demonstrate that in Xenopus neurons ACh secretion is mediated by vesicles which recycle locally within the axon. Similar to neurotransmitter release at the presynaptic nerve terminal, ACh secretion along the axon could be elicited by the action potential or by hypertonic solutions. We found that the parameters of neurotransmitter secretion at the nerve terminal and at the middle axon were strikingly similar. These results lead us to conclude that, as in the case of the presynaptic nerve terminal, synaptic vesicles involved in neurotransmitter release along the axon contain a complement of proteins for vesicle docking and Ca2+-dependent fusion. Taken together, our results support the idea that, in developing axons, the rudimentary machinery for quantal neurotransmitter secretion is distributed throughout the whole axonal surface. Maturation of this machinery in the process of synaptic development would improve the fidelity of synaptic transmission during high-frequency stimulation of the presynaptic cell.

Download Full-text

Stimulation of Ca2+-dependent neurotransmitter release and presynaptic nerve terminal protein phosphorylation by calmodulin and a calmodulin-like protein isolated from synaptic vesicles

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.76.4.1838 ◽

1979 ◽

Vol 76 (4) ◽

pp. 1838-1842 ◽

Cited By ~ 219

Author(s):

R. J. Delorenzo ◽

S. D. Freedman ◽

W. B. Yohe ◽

S. C. Maurer

Keyword(s):

Protein Phosphorylation ◽

Nerve Terminal ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

Terminal Protein ◽

Presynaptic Nerve Terminal ◽

Stimulation Of

Download Full-text

Calcium dependence of neurotransmitter release at a high fidelity synapse

10.1101/2021.05.15.444285 ◽

2021 ◽

Author(s):

Abdelmoneim Eshra ◽

Hartmut Schmidt ◽

Jens Eilers ◽

Stefan Hallermann

Keyword(s):

Synaptic Plasticity ◽

Release Rate ◽

High Frequency ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

Mossy Fiber ◽

High Fidelity ◽

Fundamental Parameters ◽

High Affinity ◽

Vesicle Pools

The Ca2+-dependence of the recruitment, priming, and fusion of synaptic vesicles are fundamental parameters controlling neurotransmitter release and synaptic plasticity. Despite intense efforts, these important steps in the synaptic vesicles cycle remain poorly understood because disentangling recruitment, priming, and fusion of vesicles is technically challenging. Here, we investigated the Ca2+-sensitivity of these steps at cerebellar mossy fiber synapses, which are characterized by fast vesicle recruitment mediating high-frequency signaling. We found that the basal free Ca2+ concentration (<200 nM) critically controls action potential-evoked release, indicating a high-affinity Ca2+ sensor for vesicle priming. Ca2+ uncaging experiments revealed a surprisingly shallow and non-saturating relationship between release rate and intracellular Ca2+ concentration up to 50 μM. Sustained vesicle recruitment was Ca2+-independent. Finally, quantitative mechanistic release schemes with five Ca2+ binding steps incorporating rapid vesicle recruitment via parallel or sequential vesicle pools could explain our data. We thus show that co-existing high and low-affinity Ca2+ sensors mediate recruitment, priming, and fusion of synaptic vesicles at a high-fidelity synapse.

Download Full-text

Rapid homeostatic modulation of transsynaptic nanocolumn rings

10.1101/2021.06.15.448550 ◽

2021 ◽

Author(s):

Paola Muttathukunnel ◽

Patrick Frei ◽

Sarah Perry ◽

Dion Dickman ◽

Martin Mueller

Keyword(s):

Glutamate Receptor ◽

Neurotransmitter Release ◽

Information Transfer ◽

Stimulated Emission ◽

Homeostatic Plasticity ◽

Synaptic Efficacy ◽

Molecular Architecture ◽

Neural Information ◽

Active Zones ◽

Chemical Synapses

Robust neural information transfer relies on a delicate molecular nano-architecture of chemical synapses. Neurotransmitter release is controlled by a specific arrangement of proteins within presynaptic active zones. How the specific presynaptic molecular architecture relates to postsynaptic organization, and how synaptic nano-architecture is transsynaptically regulated to achieve stable synaptic transmission remains enigmatic. Using time-gated stimulated emission depletion (gSTED) microscopy at the Drosophila neuromuscular junction, we here find that presynaptic nano-rings formed by the active-zone scaffold Bruchpilot (Brp) precisely align with postsynaptic glutamate receptor (GluR) rings. Individual rings harbor ~5 transsynaptically-aligned Brp-GluR nanocolumns. Intriguingly, acute GluR impairment rapidly triggers the formation of new transsynaptic nanocolumns on the minute time scale during homeostatic plasticity. We reveal distinct phases of structural transsynaptic homeostatic plasticity, with postsynaptic reorganization preceding presynaptic modulation. Finally, the auxiliary GluR subunit Neto-B; promotes structural and functional homeostatic plasticity. Thus, transsynaptic nanocolumns arrange in stereotypic rings that are rapidly modulated during homeostatic plasticity to stabilize synaptic efficacy.

Download Full-text

Faculty Opinions recommendation of Astrocyte glypicans 4 and 6 promote formation of excitatory synapses via GluA1 AMPA receptors.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717952321.793457751 ◽

2012 ◽

Author(s):

Stuart Cull-Candy ◽

Cecile Bats

Keyword(s):

Ampa Receptors ◽

Excitatory Synapses

Download Full-text

PKC-phosphorylation of Liprin-α3 triggers phase separation and controls presynaptic active zone structure

Nature Communications ◽

10.1038/s41467-021-23116-w ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Javier Emperador-Melero ◽

Man Yan Wong ◽

Shan Shan H. Wang ◽

Giovanni de Nola ◽

Hajnalka Nyitrai ◽

...

Keyword(s):

Phase Separation ◽

Active Zone ◽

Neurotransmitter Release ◽

Hippocampal Neurons ◽

Phosphorylation Site ◽

Double Knockout ◽

Zone Structure ◽

Presynaptic Nerve Terminal ◽

Condensate Formation ◽

And Function

AbstractThe active zone of a presynaptic nerve terminal defines sites for neurotransmitter release. Its protein machinery may be organized through liquid–liquid phase separation, a mechanism for the formation of membrane-less subcellular compartments. Here, we show that the active zone protein Liprin-α3 rapidly and reversibly undergoes phase separation in transfected HEK293T cells. Condensate formation is triggered by Liprin-α3 PKC-phosphorylation at serine-760, and RIM and Munc13 are co-recruited into membrane-attached condensates. Phospho-specific antibodies establish phosphorylation of Liprin-α3 serine-760 in transfected cells and mouse brain tissue. In primary hippocampal neurons of newly generated Liprin-α2/α3 double knockout mice, synaptic levels of RIM and Munc13 are reduced and the pool of releasable vesicles is decreased. Re-expression of Liprin-α3 restored these presynaptic defects, while mutating the Liprin-α3 phosphorylation site to abolish phase condensation prevented this rescue. Finally, PKC activation in these neurons acutely increased RIM, Munc13 and neurotransmitter release, which depended on the presence of phosphorylatable Liprin-α3. Our findings indicate that PKC-mediated phosphorylation of Liprin-α3 triggers its phase separation and modulates active zone structure and function.

Download Full-text