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Glutamine synthetase activity and expression are not affected by the development of motor neuronopathy in the G93A SOD-1/ALS mouse

Lookup NU author(s): Dr Anne Fray, Susan Dempster, Dr Rebecca Williams, Dr Mark Cookson, Professor Pamela Shaw

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Abstract

The expression and activity of the enzyme glutamine synthetase (GS) were examined in the G93A/SOD-1 transgenic mouse model of progressive motor neuronopathy to investigate the mechanisms underlying degeneration of the motor neurones. Clinical signs appeared in G93A/SOD-1 mice at around 90 days, with severe spasticity and loss of self-righting reflex from 120 to 150 days of age. GS expression was examined using western blotting in primary astrocyte cultures derived from newborn (P1-2) G93A/SOD-1 mice and their non-transgenic littermates and in lower spinal cord from animals at 30, 60 and 90 days of age and disease end-stage (120-150 days). There were no differences in the levels of GS expression in the transgenic mice compared to the unaffected littermates at any of the disease stages examined. GS activity was measured spectrophotometrically in spinal cord extracts at these disease stages. There was a decrease in Vmax at 60 days compared to 30 days in both groups of mice (3.48±0.58 cf. 6.43±1.83 mmol/h/mg protein; non-transgenic littermates), with GS activity highest at end-stage (9.38±0.71 mmol/h/mg protein cf. 7.64±0.42 mmol/h/mg protein in littermates). Conversely, Km was transiently increased at 60 days (2.53±0.26 mM cf. 1.32±0.20 in littermates), remaining within the range of 30 day measurements from 90 days onwards. There were no differences in Vmax or Km values between the G93A/SOD-1 mice and their unaffected non-transgenic littermates at any of the disease stages examined. We conclude that there is no evidence that a change in glutamine synthetase activity or expression contributes to the progressive neurodegeneration observed in the G93A/SOD-1 mice. © 2001 Elsevier Science B.V. All rights reserved.

Publication metadata

Author(s): Fray AE, Dempster S, Williams RE, Cookson MR, Shaw PJ

Publication type: Article

Publication status: Published

Journal: Molecular Brain Research

Year: 2001

Volume: 94

Issue: 1-2

Pages: 131-136

ISSN (print): 0169-328X

ISSN (electronic): 1872-6941

Publisher: Elsevier B.V.

URL: http://dx.doi.org/10.1016/S0169-328X(01)00228-5

DOI: 10.1016/S0169-328X(01)00228-5

PubMed id: 11597773

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