A familial ALS-linked SOD1 mutant is stabilized by SUMO3 modification.

<p>NSC34 cells were cotransfected with plasmids expressing FLAG-tagged G93R-SOD1, HA-tagged SUMO1, SUMO3, or the empty vector (vec), and myc-tagged Ubc9. After 16 h of transfection, the cells were treated with 50 µg/ml cycloheximide for 3 or 6 h or left untreated (time 0). The cell lysates were subjected to an immunoblot analysis with anti-FLAG antibody (<b>A</b> upper panel) and anti-β-actin antibody (<b>A</b> lower panel). <b>A.</b> A representative immunoblot result is shown. <b>B.</b> Quantitative analysis of the immunoblot. The intensity of each band was quantified using ImageJ and normalized to the arbitrary units of β-actin, and the means and SD (n = 4) were calculated. # indicates a statistically significant difference (p<0.01) among the three transfection conditions (vec, SUMO1, SUMO3) at time 0. Statistically significant differences (p<0.05) between time 0 of each condition are indicated by *. N.S. indicates not significant. <b>C.</b> Quantitative analysis of the immunoblot. The data in B are expressed relative to the 0 h value ( = 1).