Cleavage of the vesicular glutamate transporters under excitotoxic conditions

Research output: Contribution to journalArticle

Abstract

Glutamate is loaded into synaptic vesicles by vesicular glutamate transporters (VGLUTs), and alterations in the transporters expression directly regulate neurotransmitter release. We investigated changes in VGLUT1 and VGLUT2 protein levels after ischemic and excitotoxic insults. The results show that VGLUT2 is cleaved by calpains after excitotoxic stimulation of hippocampal neurons with glutamate, whereas VGLUT1 is downregulated to a lower extent VGLUT2 was also cleaved by calpains after oxygen/glucose deprivation (OGD), and downregulated after middle cerebral artery occlusion (MCAO) and intrahippocampal injection of kainate. In contrast, VGLUT1 was not affected after OGD. Incubation of isolated synaptic vesicles with recombinant calpain also induced VGLUT2 cleavage, with a little effect observed for VGLUT1. N-terminal sequencing analysis showed that calpain cleaves VGLUT2 in the C-terminus, at Asn(534) and Lys(542). The truncated GFP-VGWT2 forms were found to a great extent in non-synaptic regions along neurites, when compared to GFP-VGLUT2. These findings show that excitotoxic and ischemic insults downregulate VGLUT2, which is likely to affect glutamatergic transmission and cell death, especially in the neonatal period when the transporter is expressed at higher levels. (C) 2011 Elsevier Inc. All rights reserved.

Details

Authors
  • Andrea C. Lobo
  • Joao R. Gomes
  • Tatiana Catarino
  • Miranda Mele
  • Pedro Fernandez
  • Ana Inacio
  • Ben A. Bahr
  • Armanda E. Santos
  • Tadeusz Wieloch
  • Ana Luisa Carvalho
  • Carlos B. Duarte
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurosciences

Keywords

  • Brain ischemia, Calpains, Excitotoxicity, Oxygen and glucose, deprivation, Vesicular glutamate transporters
Original languageEnglish
Pages (from-to)292-303
JournalNeurobiology of Disease
Volume44
Issue number3
Publication statusPublished - 2011
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Laboratory for Experimental Brain Research (013041000)