New links between SOD1 and metabolic dysfunction from a yeast model of amyotrophic lateral sclerosis

Abstract

A number of genes have been linked to familial forms of the fatal motor neuron disease amyotrophic lateral sclerosis (ALS). Over 150 mutations within the gene encoding superoxide dismutase 1 (SOD1) have been implicated in ALS, but why such mutations lead to ALS-associated cellular dysfunction is unclear. In this study, we identify how ALS-linked SOD1 mutations lead to changes in the cellular health of the yeast Saccharomyces cerevisiae. We find that it is not the accumulation of aggregates but the loss of Sod1 protein stability that drives cellular dysfunction. The toxic effect of Sod1 instability does not correlate with a loss of mitochondrial function or increased production of reactive oxygen species, but instead prevents acidification of the vacuole, perturbs metabolic regulation and promotes senescence. Central to the toxic gain-of-function seen with the SOD1 mutants examined was an inability to regulate amino acid biosynthesis. We also report that leucine supplementation results in an improvement in motor function in a Caenorhabditis elegans model of ALS. Our data suggest that metabolic dysfunction plays an important role in Sod1-mediated toxicity in both the yeast and worm models of ALS.

A diacidic motif determines unconventional secretion of wild-type and ALS-linked mutant SOD1

“…2 A ). Next, and considering that ALS-equivalent mutations in SOD1 from different eukaryotic model organisms do not cause the same pathogenic alterations as the corresponding ALS-linked mutations in human SOD1 ( Bastow et al, 2016 ), we investigated whether the DE77/78 sequence is required for secretion of an ALS-linked mutant of human SOD1 expressed in yeast cells. Different forms of human SOD1 (wild-type, DE77/78AA, G93A, and DE77/78AA G93A) were integrated into the yeast genome, replacing the endogenous SOD1 ORF, and secretion of these human SOD1 versions was assessed using the cell wall extraction protocol followed by immunoblotting with an anti–human SOD1 antibody.…”

A quantitative model of human neurodegenerative diseases involving protein aggregation

“…Thus, the model suggests that ALS results from depletion of the large energy required for executing motor-neuron signaling (Dupuis et al, 2009). There is now support for this explanation (Bastow et al, 2016;Kitamura et al, 2014;Perera and Turner, 2016).…”

NMR metabolomics reveals effects of Cryptosporidium infections on host cell metabolome

“…The following protocol was adapted from published and well-established metabolic extraction methods used for NMR-based untargeted analysis of cell extracts [62][63][64][65]. Samples collected from the mouse experiments were retrieved from the contents of the ileum and surrounding intestinal structure.…”