Synaptotagmin-2 is essential for survival and contributes to Ca 2+ triggering of neurotransmitter release in central and neuromuscular synapses

Zhiping P. Pang, Ernestina Melicoff, Daniel Padgett, Yun Liu, Andrew F. Teich, Burton F. Dickey, Weichun Lin, Roberto Adachi, Thomas C. Südhof

Research output: Contribution to journalArticle

124 Scopus citations

Abstract

Biochemical and genetic data suggest that synaptotagmin-2 functions as a Ca2+ sensor for fast neurotransmitter release in caudal brain regions, but animals and/or synapses lacking synaptotagmin-2 have not been examined. We have now generated mice in which the 5′ end of the synaptotagmin-2 gene was replaced by lacZ. Using β-galactosidase as a marker, we show that, consistent with previous studies, synaptotagmin-2 is widely expressed in spinal cord, brainstem, and cerebellum, but is additionally present in selected forebrain neurons, including most striatal neurons and some hypothalamic, cortical, and hippocampal neurons. Synaptotagmin-2-deficient mice were indistinguishable from wild-type littermates at birth, but subsequently developed severe motor dysfunction, and perished at ∼3 weeks of age. Electrophysiological studies in cultured striatal neurons revealed that the synaptotagmin-2 deletion slowed the kinetics of evoked neurotransmitter release without altering the total amount of release. In contrast, synaptotagmin-2- deficient neuromuscular junctions (NMJs) suffered from a large reduction in evoked release and changes in short-term synaptic plasticity. Furthermore, in mutant NMJs, the frequency of spontaneous miniature release events was increased both at rest and during stimulus trains. Viewed together, our results demonstrate that the synaptotagmin-2 deficiency causes a lethal impairment in synaptic transmission in selected synapses. This impairment, however, is less severe than that produced in forebrain neurons by deletion of synaptotagmin-1, presumably because at least in NMJs, synaptotagmin-1 is coexpressed with synaptotagmin-2, and both together mediate fast Ca2+-triggered release. Thus, synaptotagmin-2 is an essential synaptotagmin isoform that functions in concert with other synaptotagmins in the Ca2+ triggering of neurotransmitter release.

Original languageEnglish (US)
Pages (from-to)13493-13504
Number of pages12
JournalJournal of Neuroscience
Volume26
Issue number52
DOIs
StatePublished - Dec 27 2006
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Keywords

  • Asynchronous release
  • Endplate
  • Neuromuscular junction
  • Striatum
  • Synapse
  • Synaptotagmin

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