DXR DEPRESSES THE ALPHA-ACTININ-INDUCED FORMATION OF ACTIN BUNDLES

The filament-to-filament interactions in cardiac alpha-actinin/F-actin mixtures were investigated in the presence of doxorubicin. Stoichiome trical concentrations of the drug in the assembly medium inhibit the g rowth of alpha-actinin/F-actin three-dimensional structures, as shown by low speed centrifugation, light scattering, A320nm, electron micros copy and low shear viscosity tests. DXR-induced short actin bundle for mation could be related to the inhibition of the bundle elongation mec hanism, and furthermore, could account for some morphological evidence s in DXR-treated living cells. Our results support both the formation pathway of actin bundles as proposed by Stokes and DeRosier (1991), an d the observations of Molinari et al. (1990) on the human CG5 cell lin e.