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Summary Heterozygous mutations in proline-rich transmembrane protein 2 (PRRT2) underlie a group of paroxysmal disorders, including epilepsy, kinesigenic dyskinesia, and migraine. Most of the mutations lead to impaired PRRT2 expression, suggesting that loss of PRRT2 function may contribute to pathogenesis. We show that PRRT2 is enriched in presynaptic terminals and that its silencing decreases the number of synapses and increases the number of docked synaptic vesicles at rest. PRRT2-silenced neurons exhibit a severe impairment of synchronous release, attributable to a sharp decrease in release probability and Ca 2+ sensitivity and associated with a marked increase of the asynchronous/synchronous release ratio. PRRT2 interacts with the synaptic proteins SNAP-25 and synaptotagmin 1/2. The results indicate that PRRT2 is intimately connected with the Ca 2+ -sensing machinery and that it plays an important role in the final steps of neurotransmitter release. [ABSTRACT FROM AUTHOR]

Loss-of-function mutations in proline-rich transmembrane protein-2 (PRRT2) cause paroxysmal disorders associated with defective Ca 2+ dependence of glutamatergic transmission. We find that either acute or constitutive PRRT2 deletion induces a significant decrease in the amplitude of evoked excitatory postsynaptic currents (eEPSCs) that is insensitive to extracellular Ca 2+ and associated with a reduced contribution of P/Q-type Ca 2+ channels to the EPSC amplitude. This synaptic phenotype parallels a decrease in somatic P/Q-type Ca 2+ currents due to a decreased membrane targeting of the channel with unchanged total expression levels. Co-immunoprecipitation, pull-down assays, and proteomics reveal a specific and direct interaction of PRRT2 with P/Q-type Ca 2+ channels. At presynaptic terminals lacking PRRT2, P/Q-type Ca 2+ channels reduce their clustering at the active zone, with a corresponding decrease in the P/Q-dependent presynaptic Ca 2+ signal. The data highlight the central role of PRRT2 in ensuring the physiological Ca 2+ sensitivity of the release machinery at glutamatergic synapses., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)