TPA induces simultaneous alterations in the synthesis and organization of vimentin

We have found an increased rate of vimentin synthesis in TPA-treated chicken embryonic fibroblasts, as shown by two-dimensional electrophoretic separation of newly synthesized polypeptides. The capacity of TPA to elicit this effect correlated with its activity as a tumor promoter. Treatment with TPA also altered the organization of the vimentin-containing intermediate filaments, as revealed by immunofluorescence. Treatments which inhibited the TPA-induced rearrangements of vimentin filaments did not prevent the increase in the rate of vimentin synthesis, indicating that gross alterations in cytoskeletal organization were not the immediate cause of the altered vimentin synthesis. On the other hand, alterations in the rate of vimentin synthesis may be a necessary, but not sufficient condition for alterations in vimentin filament organization. TPA as a positive modulator of vimentin synthesis may serve as a useful probe for an eventual understanding of the dynamics of the mechanisms that control the assembly and organization of vimentin filaments.