Colocalization of different neurotransmitter transporters on synaptic vesicles is sparse except for VGLUT1 and ZnT3

Neha Upmanyu,Jialin Jin,Henrik Von Der Emde,Marcelo Ganzella,Leon Bösche,Viveka Nand Malviya,Evi Zhuleku,Antonio Zaccaria Politi,Momchil Ninov,Ivan Silbern,Marcel Leutenegger,Henning Urlaub,Dietmar Riedel,Julia Preobraschenski,Ira Milosevic,Stefan W Hell,Reinhard Jahn,Sivakumar Sambandan

doi:10.1016/j.neuron.2022.02.008

Abstract

Vesicular transporters (VTs) define the type of neurotransmitter that synaptic vesicles (SVs) store and release. While certain mammalian neurons release multiple transmitters, it is not clear whether the release occurs from the same or distinct vesicle pools at the synapse. Using quantitative single-vesicle imaging, we show that a vast majority of SVs in the rodent brain contain only one type of VT, indicating specificity for a single neurotransmitter. Interestingly, SVs containing dual transporters are highly diverse (27 types) but small in proportion (2% of all SVs), excluding the largest pool that carries VGLUT1 and ZnT3 (34%). Using VGLUT1-ZnT3 SVs, we demonstrate that the transporter colocalization influences the SV content and synaptic quantal size. Thus, the presence of diverse transporters on the same vesicle is bona fide, and depending on the VT types, this may act to regulate neurotransmitter type, content, and release in space and time.

Highlights

Synaptic vesicles (SVs) are the trafficking organelles responsible for storage and release of various neurotransmitters at the synapse, with the type and content of the transmitters determined by the presence of specific vesicular transporters (VTs)
DyMIN STED allows high-throughput super-resolved imaging of single SVs in association with an enhanced fluorescence signal Dynamic minimum stimulated emission depletion (DyMIN STED) nanoscopy, a recently developed super-resolution microscopy technique that provides super resolution with efficient fluorescence detection, was used to image single SVs derived from rat brain
The average size of individual SVs labeled for Synaptobrevin2 (Syb2), measured in terms of the standard deviation (SD) of an integrated Gaussian fit (s) on each puncta in DyMIN STED, was $33 nm, as expected for the size of labeled SVs (Takamori et al, 2006) versus $126 nm with confocal microscopy

Summary

SUMMARY

Vesicular transporters (VTs) define the type of neurotransmitter that synaptic vesicles (SVs) store and release. While certain mammalian neurons release multiple transmitters, it is not clear whether the release occurs from the same or distinct vesicle pools at the synapse. Using quantitative single-vesicle imaging, we show that a vast majority of SVs in the rodent brain contain only one type of VT, indicating specificity for a single neurotransmitter. SVs containing dual transporters are highly diverse (27 types) but small in proportion (2% of all SVs), excluding the largest pool that carries VGLUT1 and ZnT3 (34%). Using VGLUT1-ZnT3 SVs, we demonstrate that the transporter colocalization influences the SV content and synaptic quantal size. The presence of diverse transporters on the same vesicle is bona fide, and depending on the VT types, this may act to regulate neurotransmitter type, content, and release in space and time

INTRODUCTION

RESULTS

DISCUSSION

METHOD DETAILS