‘Abnormal’ protein could be common link between all forms of motor neurone disease

Researchers have found a toxic protein that causes rare genetic forms of motor neurone disease may be involved in nerve cell death in all forms of the disorder.

Researchers have found an abnormal protein usually linked to a rare inherited form of motor neurone disease is present in all types of motor neurone disease, suggesting a common link between the different forms of the disease.

The study, published in the neuroscience journal Brain, is the first to confirm toxic changes to the protein in individuals with genetic or non-genetic forms of motor neurone disease.

Amyotrophic Lateral Sclerosis (ALS) is the most common form of motor neurone disease. Ten percent of ALS cases are hereditary, with remaining cases lacking an apparent genetic cause.

“The results suggest this abnormal protein contributes to cell death in many forms of motor neurone disease, not just rare genetic cases of motor neurone disease,” says senior author Professor Kay Double from the Brain and Mind Centre, Faculty of Medicine and Health.

“It is a big step in advancing our understanding of motor neurone disease. Our findings will direct further research and could ultimately lead to more effective treatments.”

This is a significant milestone in our understanding of ALS and motor neurone disease more broadly.

Lead author Dr Benjamin Trist

Abnormal SOD1 protein detected in human spinal cord tissue (dark spots) Trist et al. 2022.

Normally, the protein superoxide dismutase 1 (SOD1) protects cells, but a mutation in its gene is thought to make the protein ‘toxic’; this toxic protein form is associated with hereditary forms of ALS. Abnormal mutant SOD1 is only found in regions of the spinal cord where nerve cells die, implicating this abnormal protein in cell death.

Previous investigations into the role of toxic forms of SOD1 protein largely focussed on mutant forms of the protein and were primarily conducted using animal and cellular models of ALS.

The study, led by a team from the University of Sydney’s Brain and Mind Centre, advances our understanding of the causes of motor neurone disease by studying this abnormal protein in post-mortem tissues from patients with ALS.

“We have shown for the first time that mechanisms of disease long hypothesised to occur in animal and cellular models are present in patients with motor neurone disease,” says lead author Dr Benjamin Trist from the Brain and Mind Centre, Faculty of Medicine and Health.

“This is a significant milestone in our understanding of ALS and motor neurone disease more broadly.”

In related experiments, Professor Double and her team are also currently studying how abnormal SOD1 interacts with other disease-linked proteins in motor neurone disease. This work is in press and will be published in Acta Neuropathologica Communications.

Declaration: The researchers declare no conflict of interest. Samples were obtained from the MRC London Neurodegenerative Diseases Brain Bank, and the University of Maryland Brain and Tissue brain bank, a bio repository of the NIH NeuroBioBank. Ethics approval was obtained from the University of Sydney Human Research Ethics Committee.

Hero image credit: Ella Maru

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