RT Journal Article
SR Electronic
T1 Light-Activated ROS Production Induces Synaptic Autophagy
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 2163
OP 2183
DO 10.1523/JNEUROSCI.1317-18.2019
VO 39
IS 12
A1 Sheila Hoffmann
A1 Marta Orlando
A1 Ewa Andrzejak
A1 Christine Bruns
A1 Thorsten Trimbuch
A1 Christian Rosenmund
A1 Craig C. Garner
A1 Frauke Ackermann
YR 2019
UL http://www.jneurosci.org/content/39/12/2163.abstract
AB The regulated turnover of synaptic vesicle (SV) proteins is thought to involve the ubiquitin-dependent tagging and degradation through endo-lysosomal and autophagy pathways. Yet, it remains unclear which of these pathways are used, when they become activated, and whether SVs are cleared en masse together with SV proteins or whether both are degraded selectively. Equally puzzling is how quickly these systems can be activated and whether they function in real-time to support synaptic health. To address these questions, we have developed an imaging-based system that simultaneously tags presynaptic proteins while monitoring autophagy. Moreover, by tagging SV proteins with a light-activated ROS generator, Supernova, it was possible to temporally control the damage to specific SV proteins and assess their consequence to autophagy-mediated clearance mechanisms and synaptic function. Our results show that, in mouse hippocampal neurons of either sex, presynaptic autophagy can be induced in as little as 5–10 min and eliminates primarily the damaged protein rather than the SV en masse. Importantly, we also find that autophagy is essential for synaptic function, as light-activated damage to, for example, Synaptophysin only compromises synaptic function when autophagy is simultaneously blocked. These data support the concept that presynaptic boutons have a robust highly regulated clearance system to maintain not only synapse integrity, but also synaptic function.SIGNIFICANCE STATEMENT The real-time surveillance and clearance of synaptic proteins are thought to be vital to the health, functionality, and integrity of vertebrate synapses and are compromised in neurodegenerative disorders, yet the fundamental mechanisms regulating these systems remain enigmatic. Our analysis reveals that presynaptic autophagy is a critical part of a real-time clearance system at synapses capable of responding to local damage of synaptic vesicle proteins within minutes and to be critical for the ongoing functionality of these synapses. These data indicate that synapse autophagy is not only locally regulated but also crucial for the health and functionality of vertebrate presynaptic boutons.