Expression of SOD1 G93A or wild-type SOD1 in primary cultures of astrocytes down-regulates the glutamate transporter GLT-1: lack of involvement of oxidative stress

Massimo Tortarolo, Andrew J Crossthwaite, Laura Conforti, Jeremy P Spencer, Robert J Williams, Caterina Bendotti, Marcus Rattray

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Glutamate excitotoxicity is implicated in the aetiology of amyotrophic lateral sclerosis (ALS) with impairment of glutamate transport into astrocytes a possible cause of glutamate-induced injury to motor neurons. It is possible that mutations of Cu/Zn superoxide dismutase (SOD1), responsible for about 20% of familial ALS, down-regulates glutamate transporters via oxidative stress. We transfected primary mouse astrocytes to investigate the effect of the FALS-linked mutant hSOD1(G93A) and wild-type SOD1 (hSOD1wt) on the glutamate uptake system. Using western blotting, immunocytochemistry and RT-PCR it was shown that expression of either hSOD1(G93A) or hSOD1wt in astrocytes produced down-regulation of the levels of a glutamate transporter GLT-1, without alterations in its mRNA level. hSOD1(G93A) or hSOD1wt expression caused a decrease of the monomeric form of GLT-1 without increasing oxidative multimers of GLT-1. The effects were selective to GLT-1, since another glutamate transporter GLAST protein and mRNA levels were not altered. Reflecting the decrease in GLT-1 protein, [3H]d-aspartate uptake was reduced in cultures expressing hSOD1(G93A) or hSOD1wt. The hSOD1-induced decline in GLT-1 protein and [3H]d-aspartate uptake was not blocked by the antioxidant Trolox nor potentiated by antioxidant depletion using catalase and glutathione peroxidase inhibitors. Measurement of 2',7'-dichlorofluorescein (DCF)-induced fluorescence revealed that expression of hSOD1(G93A) or hSOD1wt in astrocytes does not lead to detectable increase of intracellular reactive oxygen species. This study suggests that levels of GLT-1 protein in astrocytes are reduced rapidly by overexpression of hSOD1, and is due to a property shared between the wild-type and G93A mutant form, but does not involve the production of intracellular oxidative stress.
Original languageEnglish
Pages (from-to)481-93
Number of pages13
JournalJournal of Neurochemistry
Volume88
Issue number2
DOIs
Publication statusPublished - 2004

Fingerprint Dive into the research topics of 'Expression of SOD1 G93A or wild-type SOD1 in primary cultures of astrocytes down-regulates the glutamate transporter GLT-1: lack of involvement of oxidative stress'. Together they form a unique fingerprint.

Cite this