title: Motor neuropathy-associated mutation impairs Seipin functions in neurotransmission.
abstract: 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.
authors.affiliation: Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore.
authors.forename: Shunhui
authors.initials: S
authors.lastname: Wei
authors.forename: Stephanie Li-Ying
authors.initials: SL
authors.lastname: Soh
authors.forename: Julia
authors.initials: J
authors.lastname: Xia
authors.forename: Wei-Yi
authors.initials: WY
authors.lastname: Ong
authors.forename: Zhiping P
authors.initials: ZP
authors.lastname: Pang
authors.forename: Weiping
authors.initials: W
authors.lastname: Han
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D044388:GTP-Binding Protein gamma Subunits; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D005822:Genetic Vectors; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D016086:Lentivirus / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D016472:Motor Neuron Disease / Q000235:genetics*; D020125:Mutation, Missense / Q000235:genetics* / Q000502:physiology*; D015419:Spastic Paraplegia, Hereditary / Q000235:genetics / Q000503:physiopathology; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000235:genetics* / Q000502:physiology*
chemical_list: C115783:Bscl2 protein, mouse; D044388:GTP-Binding Protein gamma Subunits; D020962:Heterotrimeric GTP-Binding Proteins
keywords: AMPA receptor; EPSC; GABA; IPSC; glutamate; neurotransmission