Rapid recycling of glutamate transporters on the astroglial surface

eLife

Janosch Peter Heller¹  Dmitri A Rusakov²  Piotr Michaluk² 

[1] BRAINCITY, Laboratory of Neurobiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland;UCL Queen Square Institute of Neurology, University College London, London, United Kingdom;

关键词: glutamate uptake;    synaptic transmission;    GLT-1;    Super-Ecliptic pHluorin;    astrocytes;    membrane transport;   

DOI  :  10.7554/eLife.64714

来源: DOAJ

【 摘 要 】

Glutamate uptake by astroglial transporters confines excitatory transmission to the synaptic cleft. The efficiency of this mechanism depends on the transporter dynamics in the astrocyte membrane, which remains poorly understood. Here, we visualise the main glial glutamate transporter GLT1 by generating its pH-sensitive fluorescent analogue, GLT1-SEP. Fluorescence recovery after photobleaching-based imaging shows that 70–75% of GLT1-SEP dwell on the surface of rat brain astroglia, recycling with a lifetime of ~22 s. Genetic deletion of the C-terminus accelerates GLT1-SEP membrane turnover while disrupting its surface pattern, as revealed by single-molecule localisation microscopy. Excitatory activity boosts surface mobility of GLT1-SEP, involving its C-terminus, metabotropic glutamate receptors, intracellular Ca2+, and calcineurin-phosphatase activity, but not the broad-range kinase activity. The results suggest that membrane turnover, rather than lateral diffusion, is the main 'redeployment' route for the immobile fraction (20–30%) of surface-expressed GLT1. This finding reveals an important mechanism helping to control extrasynaptic escape of glutamate.

【 授权许可】

Unknown