Epileptogenic Q555X SYN1 mutant triggers imbalances in release dynamics and short-term plasticity

Gabriele Lignani, Andrea Raimondi, Enrico Ferrea, Anna Rocchi, Francesco Paonessa, Fabrizia Cesca, Marta Orlando, Tatiana Tkatch, Flavia Valtorta, Patrick Cossette, Pietro Baldelli, Fabio Benfenati*

*Corresponding author for this work

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

Synapsin I (SynI) is a synaptic vesicle (SV) phosphoprotein playing multiple roles in synaptic transmission and plasticity by differentially affecting crucial steps of SV trafficking in excitatory and inhibitory synapses. SynI knockout (KO) mice are epileptic, and nonsense and missense mutations in the human SYN1 gene have a causal role in idiopathic epilepsy and autism. To get insights into the mechanisms of epileptogenesis linked to SYN1 mutations, we analyzed the effects of the recently identified Q555X mutation on neurotransmitter release dynamics and short-term plasticity (STP) in excitatory and inhibitory synapses. We used patch-clamp electrophysiology coupled to electron microscopy and multi-electrode arrays to dissect synaptic transmission of primary SynI KO hippocampal neurons in which the human wild-type and mutant SynI were expressed by lentiviral transduction. A parallel decrease in the SV readily releasable pool in inhibitory synapses and in the release probability in excitatory synapses caused a marked reduction in the evoked synchronous release. This effect was accompanied by an increase in asynchronous release that was much more intense in excitatory synapses and associated with an increased total charge transfer. Q555X-hSynI induced larger facilitation and post-tetanic potentiation in excitatory synapses and stronger depression after long trains in inhibitory synapses. These changes were associated with higher network excitability and firing/bursting activity. Our data indicate that imbalances in STP and release dynamics of inhibitory and excitatory synapses trigger network hyperexcitability potentially leading to epilepsy/autism manifestations.

Original languageEnglish (US)
Pages (from-to)2186-2199
Number of pages14
JournalHuman molecular genetics
Volume22
Issue number11
DOIs
StatePublished - Jun 1 2013

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ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Genetics(clinical)

Cite this

Lignani, G., Raimondi, A., Ferrea, E., Rocchi, A., Paonessa, F., Cesca, F., Orlando, M., Tkatch, T., Valtorta, F., Cossette, P., Baldelli, P., & Benfenati, F. (2013). Epileptogenic Q555X SYN1 mutant triggers imbalances in release dynamics and short-term plasticity. Human molecular genetics, 22(11), 2186-2199. https://doi.org/10.1093/hmg/ddt071