Dynamic control of synaptic vesicle replenishment and short-term plasticity by Ca(2+)-calmodulin-Munc13-1 signaling.


Lipstein N, Sakaba T, Cooper BH, Lin KH, Strenzke N, Ashery U, Rhee JS, Taschenberger H, Neher E, Brose N.

Neuron. 2013 Jul 10;79(1):82-96. doi: 10.1016/j.neuron.2013.05.011. Epub 2013 Jun 13.

Short-term synaptic plasticity, the dynamic alteration of synaptic strength during high-frequency activity, is a fundamental characteristic of all synapses. At the calyx of Held, repetitive activity eventually results in short-term synaptic depression, which is in part due to the gradual exhaustion of releasable synaptic vesicles. This is counterbalanced by Ca(2+)-dependent vesicle replenishment, but the molecular mechanisms of this replenishment are largely unknown. We studied calyces of Held in knockin mice that express a Ca(2+)-Calmodulin insensitive Munc13-1(W464R) variant of the synaptic vesicle priming protein Munc13-1. Calyces of these mice exhibit a slower rate of synaptic vesicle replenishment, aberrant short-term depression and reduced recovery from synaptic depression after high-frequency stimulation. Our data establish Munc13-1 as a major presynaptic target of Ca(2+)-Calmodulin signaling and show that the Ca(2+)-Calmodulin-Munc13-1 complex is a pivotal component of the molecular machinery that determines short-term synaptic plasticity characteristics.

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