Dynamin is primed at endocytic sites for ultrafast endocytosis

Imoto, Yuuta; Raychaudhuri, Sumana; Fenske, Pascal; Sandoval, Eduardo; Itoh, Kie; Blumrich, Eva-Maria; Mamer, Lauren; Zarebidaki, Fereshteh; Söhl-Kielczynski, Berit; Trimbuch, Thorsten; Nayak, Shraddha; Iwasa, Janet; Jørgensen, Erik M.; Cousin, Michael A.; Rosenmund, Christian; Watanabe, Shigeki

doi:10.1101/2021.02.15.431332

Cited by 12 publications

(34 citation statements)

References 102 publications

(160 reference statements)

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“…The phosphomimetic form of Dyn1xA cannot form liquid-like droplets and is diffuse throughout the cytoplasm similar to Syndapin 1 knock down phenotype which slows down ultrafast endocytosis in previous study (Imoto et al, 2021). Together, these results suggest that the liquid-like properties of Dyn1xA and Syndapin 1 are important for ultrafast endocytosis.…”

Section: Introductionsupporting

confidence: 72%

“…To examine the requirement for dephosphorylation, we localized wild-type, phosphomimetic (S774/778D), and phospho-deficient (S774/778A) forms of Dyn1xA in neurons. We visualized Dyn1xA-GFP along with an active zone protein, Bassoon, using Stimulated Emission Depletion (STED) microscopy (Figure 2K (Imoto et al, 2021), most Dyn1xA signals were found within 100 nm from the active zone edge where ultrafast endocytosis takes place (Watanabe et al, 2013a). Likewise, phosphodeficient Dyn1xA accumulated within 100 nm from the active zone edge.…”

Section: Phase Separation Of Dyn1xa At Synapses Requires Dephosphoryl...mentioning

confidence: 99%

“…Like the exocytic machinery, endocytic proteins that control the recycling of synaptic vesicles also possess the molecular characteristics necessary for phase separation and colocalize at synapses. A splice variant of Dynamin 1, Dyn1xA, is localized at the presynaptic endocytic zone by its interaction with the Fer-CIP4 homology-BAR (F-BAR) containing protein Syndapin 1 (Imoto et al, 2021). The C-terminus of Dyn1xA contains a 20 amino acid extension with extra binding motifs for SH3-containing proteins (Huang et al, 2004), providing multivalency.…”

Section: Introductionmentioning

confidence: 99%

“…The C-terminus of Dyn1xA contains a 20 amino acid extension with extra binding motifs for SH3-containing proteins (Huang et al, 2004), providing multivalency. This region is essential for ultrafast endocytosis – another splice variant, Dyn1xB, which lacks this extension, cannot support ultrafast endocytosis (Imoto et al, 2021). Like other proteins that phase separate (Banani et al, 2017; Li et al, 2012; Milovanovic et al, 2018; Pechstein et al, 2020), this interaction is mediated by low-complexity motifs: the proline-rich motif (PRM) of Dyn1xA and the Src-Homology 3 (SH3) domain of Syndapin 1.…”

Section: Introductionmentioning

confidence: 99%

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Dynamin forms liquid-like condensates at synapses to support ultrafast endocytosis

Imoto

Itoh

et al. 2022

Preprint

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Endocytosis at synapses is accelerated by the pre-accumulation of Dynamin 1xA at the endocytic zone by Syndapin 1. However, it is unclear how these proteins support the ultrafast kinetics of endocytosis. Here we report that these proteins phase separate at the presynaptic endocytic zone where ultrafast endocytosis takes place. Specifically, the proline-rich motif of Dynamin 1xA interacts with the Src-Homology 3 domain of Syndapin 1 and forms liquid-like condensates. Single-particle tracking of Dynamin 1xA molecules at synapses shows that their diffusion slows down substantially when they are in the condensates, indicating the presence of molecular crowding and intermolecular interaction. When Dynamin 1xA is mutated to disrupt its interaction with Syndapin 1 the condensates do not form. Thus, the liquid-like assembly of these endocytic proteins provides a catalytic platform for ultrafast endocytosis.

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Section: Introductionsupporting

confidence: 72%

Section: Phase Separation Of Dyn1xa At Synapses Requires Dephosphoryl...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dynamin forms liquid-like condensates at synapses to support ultrafast endocytosis

Imoto

Itoh

et al. 2022

Preprint

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“…We first examined SDPN-1/syndapin 1, a protein known to play important roles in early stages of membrane invagination during both activity-dependent bulk endocytosis (ADBE) 89,90 and ultrafast endocytosis 91 . We reasoned that if ATG-9…”

Section: Ap-1 Adaptor Complexmentioning

confidence: 99%

The active zone protein Clarinet regulates ATG-9 trafficking at synapses and presynaptic autophagy

Zhao

Yang

Hill

et al. 2021

Preprint

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In neurons, autophagy is temporally and spatially regulated to occur near presynaptic sites. How trafficking of autophagy proteins is regulated to support synaptic autophagy is not well understood. From forward genetic screens, we identify a role for the long isoform of the active zone protein Clarinet (CLA-1L) in regulating trafficking of autophagy protein ATG-9 at synapses, and presynaptic autophagy. ATG-9 is a transmembrane protein that undergoes activity-dependent exo-endocytosis at synapses, and mutations in CLA-1L result in abnormal accumulation of ATG-9 into clathrin-rich endocytic intermediates. CLA-1L extends from the active zone to the periactive zone, and genetically interacts with periactive zone proteins required for clathrin-dependent endocytosis. We find that CLA-1L is specifically required for sorting of ATG-9 at synapses, likely via endosome-mediated endocytosis, and for activity-dependent presynaptic autophagy. Our findings provide mechanistic insights into how active zone proteins regulate key steps of ATG-9 exo-endocytosis, a process that could couple the activity state of the neuron and autophagy.

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Membrane compression by synaptic vesicle exocytosis triggers ultrafast endocytosis

et al. 2023

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Compensatory endocytosis keeps the membrane surface area of secretory cells constant following exocytosis. At chemical synapses, clathrin-independent ultrafast endocytosis maintains such homeostasis. This endocytic pathway is temporally and spatially coupled to exocytosis; it initiates within 50 ms at the region immediately next to the active zone where vesicles fuse. However, the coupling mechanism is unknown. Here, we demonstrate that filamentous actin is organized as a ring, surrounding the active zone at mouse hippocampal synapses. Assuming the membrane area conservation is due to this actin ring, our theoretical model suggests that flattening of fused vesicles exerts lateral compression in the plasma membrane, resulting in rapid formation of endocytic pits at the border between the active zone and the surrounding actin-enriched region. Consistent with model predictions, our data show that ultrafast endocytosis requires sufficient compression by exocytosis of multiple vesicles and does not initiate when actin organization is disrupted, either pharmacologically or by ablation of the actin-binding protein Epsin1. Our work suggests that membrane mechanics underlie the rapid coupling of exocytosis to endocytosis at synapses.

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Dynamin is primed at endocytic sites for ultrafast endocytosis

Cited by 12 publications

References 102 publications

Dynamin forms liquid-like condensates at synapses to support ultrafast endocytosis

Dynamin forms liquid-like condensates at synapses to support ultrafast endocytosis

The active zone protein Clarinet regulates ATG-9 trafficking at synapses and presynaptic autophagy

Membrane compression by synaptic vesicle exocytosis triggers ultrafast endocytosis

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