Scripties UMCG - Rijksuniversiteit Groningen
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The effect of mutant SOD1 on cell viability

(2016) Boertien, L.M.

Mutations in the gene encoding for superoxide dismutase 1 (mSOD1) lead to protein aggregation and
are associated with 20% of familial amyotrophic lateral sclerosis (ALS) cases. Multiple molecular
chaperones are known to influence mSOD1 aggregation and cytotoxicity. Still, the relation between
protein aggregation and cytotoxicity remains elusive.
In the current project, human osteosarcoma cell lines stably expressing SOD1-WT or SOD1-A4V
(U2OS-WT, U2OS-A4V) were exposed to endoplasmatic reticular stress, proteasomal inhibition and
autophagy inhibition. Phenotypes of SOD1-A4V cytotoxicity were then correlated to levels of mSOD1
expression and aggregation. Additionally, overexpression of the molecular chaperones HSPA1A and
HSPA1L was investigated for their potential to rescue the mSOD1 associated phenotype.
Endoplasmatic reticular (ER) stress induced by Tunicamycin treatment was the only stressor that
produced a reproducible phenotype characterised by a decrease in U2OS-A4V cell viability compared
to U2OS-WT. No correlation with mSOD1 aggregation could be established. HSPA1A and HSPA1L
overexpression both resulted in a marginal relative rescue of cell viability specific to U2OS-A4V under
Tunicamycin treatment.
Interpretation of the results was hampered by the marginal differences in cell viability, the low
expression levels of SOD1-A4V and the expression of endogenous SOD1. An experimental
endogenous SOD1 knockout model, with expression levels of the proteins of interest close to
endogenous expression of SOD1, is proposed to substantiate the findings of this study. Further
investigation of the relationship between ER stress and mSOD1 cytotoxicity can be centred around
the in literature described interaction between mSOD1 and Derlin-1, through which mSOD1 is
proposed to mediate its cytotoxicity.

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