Oxidative modification of SOD1 as a mechanism of pathological aging
Date
2020-08-06
Authors
Shafiq, Kashfia
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Aging-associated stress induces post-translational oxidation at cysteine 111 residue in both mutant and wild type of SOD1, which is one of our primary antioxidant enzymes. Such oxidatively modified SOD1 influences the oxidation of other native proteins in its vicinity and becomes misfolded and forms aggregates that propagate in a prion-like manner from cell to cell in age-related diseases like ALS, AD- and PD. Assuming the cumulative consequence, we have hypothesized that oxidatively modified SOD1 is a mechanism of pathological aging. Both in vivo and in vitro, we have utilized the mutant human SOD1 (G93A) as a tool to prove this hypothesis as they are the most commonly studied model for ALS research and more vulnerable to oxidative stress than the wild varieties. Hence, pathological consequences are more conspicuous and understandable. Western blot analyses and immunofluorescence studies were performed in N2a cells, transiently transfected with G93A plasmid constructs, which revealed robust senescence compared with the cells transfected with wild type SOD1. In addition, MalPEG modification and subsequent WB analysis of the spinal cord tissues collected from the different age groups of G93A transgenic mice showed that oxidative modification of human SOD1 increased in an age-dependent manner that coincided with the rise of cellular senescence. Then, we selectively knocked down this modified human SOD1 by transfecting the N2a cells with CT4 plasmid construct that were initially transfected with G93A and by injecting CT4 fusion peptide intraperitoneally for one month to the G37R transgenic mice. The binding efficiency of CT4 peptide to modified human SOD1 was confirmed by GST pull-down assay. MalPEG modification and western blot analysis demonstrated a significant decrease of oxidatively modified human SOD1 and cellular senescence in both experimental models after implicating the peptide treatment. The findings are in agreement with our hypothesis; oxidized SOD1 is a mechanism of cellular aging in ALS pathogenesis. Besides, CT4 mediated knockdown of modified SOD1 could be an effective strategy to prevent cellular aging and early death.
Description
Keywords
Aging, SOD1, ALS, Senescence