The proteasome inhibitor MG132 extends FL-SMN and a-SMN protein half-life.

<p>Representative Western blots (<b>A)</b> and bar graphs (<b>B</b>: OD ratio vs actin) of FL-SMN and a-SMN protein expression levels after cycloheximide (CHX) treatment in the presence <b>(A</b>, left<b>)</b> or absence <b>(A</b>, right<b>)</b> of MG132. The “+” and “-”indications represent the presence or absence, respectively, of MG132 and CHX. NSC34 cells were first co-transfected with N-terminally tagged human FL-SMN and a-SMN, then treated with CHX for 0, 1, 3, 5 and 7 hrs with or without MG132. The MG132 treatment significantly increased the a-SMN half-life at all time-point considered (<b>B</b>, left), whereas the MG132 effect on FL-SMN was not statistically significant (<b>B</b>, right). Data in <b>B</b> are presented as mean ± SEM of three different experiments. For both FL-SMN and a-SMN, distinct statistical analysis was performed by Student’s t-test between groups w/o and with MG132 treatment at each time points considered (n.s. = not significant; *p<0.05; **p<0.01; #p<0.001).