Alterations in protein synthesis induced by C2 toxin in 3T3 cells

We have studied the effect of actin skeleton depolymerisation induced by C2 toxin on protein synthesis in 3T3 cells. The toxin that was purified from culture medium of Clostridium botulinum type C was shown to specifically ADP-ribosylate actin in vitro and in vivo. Cells exposed to C2 toxin were rounded off, which was accompanied by disappearance of stress fibers. The rate of total protein synthesis decreased two-three times in the treated cells. This correlated with the reduction in amount of polyribosomes. The rates of specific protein synthesis were compared using 2D electrophoresis of pulse-labeled proteins. Dramatic changes were observed in the synthesis of a small group of cellular proteins. Our results indicate that actin filament depolymerization affects gene expression at the level of translation and/or through the control of mRNA concentrations.