Characterisation of Superoxide Dismutase 1 Protein in canine degenerative myelopathy

Qi, Yao (2016) Characterisation of Superoxide Dismutase 1 Protein in canine degenerative myelopathy. MSc(R) thesis, University of Glasgow.

Abstract

Canine degenerative myelopathy (DM), is an adult-onset and fatal disease that was initially described in German Shepherd dogs (GSD) although it has also been found in other breeds. It is characterised by bilateral ataxia affecting the pelvic limbs with progression over time to quadriplegia. A point mutation 118G>A (E40K) in the canine Sod1 gene was recently reported in the majority of DM-affected dogs. This has raised the possibility that DM may be orthologous to familial amyotrophic lateral sclerosis (fALS) which is also associated with a variety of mutations of the SOD1 gene. It has been proposed that SOD1 mutations in fALS result in misfolded SOD1 proteins inducing a toxic action of the protein. However, the impact of the Sod1 mutations in DM on the properties and consequent function of SOD1 protein are currently unknown in both the homozygous and heterozygous situations. Furthermore, the influence of the canine Sod1 mutation on the wild type (WT) gene, which occurs in the heterozygote genotype, is unknown.
This study investigated the impact of the DM Sod1 mutation on the biochemical properties and cellular distribution of the WT SOD1 protein. A dual strategy approach was employed using tissue derived from control and DM cases and by an in vitro cell transfection approach using WT and mutant Sod1 cDNA constructs tagged with fluorescent proteins. This study found that expression of the mutated Sod1 cDNA constructs in transfected cells leads to aggregate-like accumulation of SOD1. Additionally, SOD1 aggregates also occurred in cells co-transfected with both mutant and WT plasmids suggesting some form of co-localization. A biochemical investigation of tissue from control and DM dogs found that the level of SOD1 was reduced in DM total homogenates and membrane-enriched fraction although the soluble cytoplasmic levels were unaltered. SOD1 in both the cytoplasmic and membrane fractions, had similar NP40 solubility characteristics in DM and control tissue. This study demonstrated that the Sod1 mutation induces selective alterations in the properties of SOD1 and may provide clues as to the nature of this late onset progressive disorder. Understanding the impact of the Sod1 mutation in DM may extend our understanding of the pathomechanism of the disease and provide further evidence that DM is a useful model of fALS.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: canine degenerative myelopathy, SOD1 protein, Sod1 mutation
• Subjects: Q Science > QH Natural history > QH301 Biology; Q Science > QH Natural history > QH345 Biochemistry; R Medicine > R Medicine (General)
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Supervisor's Name: McLaughlin, Dr. Mark, Anderson, Dr. Thomas and Montague, Dr. Paul
• Date of Award: 2016
• Embargo Date: 16 January 2020
• Depositing User: Mrs Yao Qi
• Unique ID: glathesis:2016-7065
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 04 Feb 2016 08:25
• Last Modified: 13 Aug 2019 12:41
• URI: https://theses.gla.ac.uk/id/eprint/7065