The motor system is exceptionally vulnerable to absence of the ubiquitously expressed superoxide dismutase-1.
Julien H ParkUlrika NordströmKonstantinos TsiakasIsil KeskinChristiane ElpersManoj MannilRaoul HellerMelinda NolanSalam AlburaikyPer ZetterströmMaja HempelUlrike Schara-SchmidtSaskia BiskupPetra SteinackerMarkus OttoJochen WeishauptAndreas HahnRené SanterThorsten MarquardtStefan L MarklundPeter M AndersenPublished in: Brain communications (2023)
Superoxide dismutase-1 is a ubiquitously expressed antioxidant enzyme. Mutations in SOD1 can cause amyotrophic lateral sclerosis, probably via a toxic gain-of-function involving protein aggregation and prion-like mechanisms. Recently, homozygosity for loss-of-function mutations in SOD1 has been reported in patients presenting with infantile-onset motor neuron disease. We explored the bodily effects of superoxide dismutase-1 enzymatic deficiency in eight children homozygous for the p.C112Wfs*11 truncating mutation. In addition to physical and imaging examinations, we collected blood, urine and skin fibroblast samples. We used a comprehensive panel of clinically established analyses to assess organ function and analysed oxidative stress markers, antioxidant compounds, and the characteristics of the mutant Superoxide dismutase-1. From around 8 months of age, all patients exhibited progressive signs of both upper and lower motor neuron dysfunction, cerebellar, brain stem, and frontal lobe atrophy and elevated plasma neurofilament concentration indicating ongoing axonal damage. The disease progression seemed to slow down over the following years. The p.C112Wfs*11 gene product is unstable, rapidly degraded and no aggregates were found in fibroblast. Most laboratory tests indicated normal organ integrity and only a few modest deviations were found. The patients displayed anaemia with shortened survival of erythrocytes containing decreased levels of reduced glutathione. A variety of other antioxidants and oxidant damage markers were within normal range. In conclusion, non-neuronal organs in humans show a remarkable tolerance to absence of Superoxide dismutase-1 enzymatic activity. The study highlights the enigmatic specific vulnerability of the motor system to both gain-of-function mutations in SOD1 and loss of the enzyme as in the here depicted infantile superoxide dismutase-1 deficiency syndrome.
Keyphrases
- oxidative stress
- hydrogen peroxide
- amyotrophic lateral sclerosis
- end stage renal disease
- newly diagnosed
- ejection fraction
- chronic kidney disease
- dna damage
- multiple sclerosis
- spinal cord injury
- young adults
- anti inflammatory
- nitric oxide
- copy number
- high resolution
- climate change
- mass spectrometry
- gene expression
- ischemia reperfusion injury
- transcription factor
- induced apoptosis
- soft tissue
- diabetic rats
- patient reported
- replacement therapy
- optic nerve
- free survival