Motor neuropathy-associated mutation impairs Seipin functions in neurotransmission
Version of Record online: 8 JAN 2014
© 2013 International Society for Neurochemistry
Journal of Neurochemistry
Volume 129, Issue 2, pages 328–338, April 2014
How to Cite
J. Neurochem. (2014) 129, 328–338.
- Issue online: 4 APR 2014
- Version of Record online: 8 JAN 2014
- Accepted manuscript online: 18 DEC 2013 02:49AM EST
- Manuscript Accepted: 12 DEC 2013
- Manuscript Revised: 18 NOV 2013
- Manuscript Received: 16 SEP 2013
- Agency for Science, Technology and Research
- Biomedical Research Council
- Robert Wood Johnson Foundation
- AMPA receptor;
- EPSC ;
- GABA ;
- IPSC ;
Gain-of-toxic-function mutations in Seipin (Asparagine 88 to Serine (N88S) and Serine 90 to Leucine (S90L) mutations, both of which disrupt the N-glycosylation) cause autosomal dominant motor neuron diseases. However, the mechanism of how these missense mutations lead to motor neuropathy is unclear. Here, we analyze the impact of disruption of N-glycosylation of Seipin on synaptic transmission by over-expressing mutant Seipin in cultured cortical neurons via lentiviral infection. Immunostaining shows that over-expressed Seipin is partly colocalized with synaptic vesicle marker synaptophysin. Electrophysiological recordings reveal that the Seipin mutation significantly decreases the frequency, but not the amplitudes of miniature excitatory post-synaptic currents and miniature inhibitory post-synaptic currents. The amplitude of both evoked excitatory post-synaptic currents and inhibitory post-synaptic current is also compromised by mutant Seipin over-expression. The readily releasable pool and vesicular release probability of synaptic vesicles are both altered in neurons over-expressing Seipin-N88S, whereas neither γ-amino butyric acid (GABA) nor α-Amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) induced whole cell currents are affected. Moreover, electron microscopy analysis reveals decreased number of morphologically docked synaptic vesicles in Seipin-N88S-expressing neurons. These data demonstrate that Seipin-N88S mutation impairs synaptic neurotransmission, possibly by regulating the priming and docking of synaptic vesicles at the synapse.
Motoneuropathy-associated endoplasmic reticulum (ER) protein Seipin-N88S mutation disrupts N-glycosylation and decreased the frequency of miniature excitatory and inhibitory post-synaptic currents (PSCs), and the amplitude of evoked excitatory and inhibitory PSCs. The readily releasable pool and synaptic vesicle (SV) release probability were reduced in neurons over-expressing Seipin-N88S, along with decreased number of docked vesicles. We propose that Seipin-N88S mutation impairs synaptic neurotransmission by regulating the docking of synaptic vesicles.