Local regulation of extracellular vesicle traffic by the synaptic endocytic machinery

Abstract

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.

Quantitative mapping of synaptic periactive zone architecture and organization

“…Does stronger Dyn accumulation in the PAZ core reflect its roles in modes of endocytosis that occur proximal to release sites, including ultrafast endocytosis (Kidokoro, 2006; Koenig and Ikeda, 1996; Kosaka and Ikeda, 1983; Kuromi et al, 2010; Teng and Wilkinson, 2000; Watanabe et al, 2013a)? Are more peripheral PAZ proteins held in a ‘poised’ or inactive state, or are they engaged in more diverse synaptic functions beyond synaptic vesicle endocytosis (Blanchette et al, 2022; Gimber et al, 2015; Jäpel et al, 2020; O’Connor-Giles et al, 2008; Rodal et al, 2011, 2008)? Alternatively, this heterogeneity could also reflect different temporal stages of a single biological process (such as stages of endocytosis).…”

“…They are especially interesting to consider as PAZ constituents because they regulate endocytosis and synaptic vesicle trafficking (Dagar et al, 2021; Leshchyns’ka et al, 2006; Luo et al, 2021; Shetty et al, 2013; van Stegen et al, 2017), and are themselves endocytic cargoes. Indeed, presynaptic endocytosis and trafficking pathways regulate the levels and function of adhesion molecules (Bailey et al, 1992; Blanchette et al, 2022; Fu and Huang, 2010; Kurshan et al, 2018; Nahm et al, 2016; Yamada et al, 2007). Therefore, in addition to being important components of the PAZ, adhesion molecules are crucial regulators and effectors of the endocytic machinery at the synapse.…”

Role of Bin‐Amphiphysin‐Rvs (BAR) domain proteins in mediating neuronal signaling and disease

“…Additionally, the role of the nervous wreck (Nwk) has been studied at the presynaptic terminal controlling neuronal extracellular vehicles (EVs) cargos in neurons (Blanchette et al., 2021). Further shreds of evidence have shown that it interacts with thickveins to regulate BMP signaling during synaptic growth (O'Connor‐Giles et al., 2008).…”