Restoration of microfilament bundle organization in v-raf-transformed NRK cells after transduction with tropomyosin 2 cDNA.

The syntheses of tropomyosin (TM) isoforms, especially those of TM1 and TM2, were suppressed in v-raf-transformed NRK cells. To test whether restoration of one of the suppressed TM expressions affects cellular phenotypes of v-raf-transformed NRK cells, the cells were transduced with mouse fibroblast TM2 cDNA by retrovirally mediated DNA transfer method. Clones expressing the inserted TM2 cDNA and accordingly higher amounts of TM2 than the parental and control clones displayed a flatter morphology which was accompanied by partial restoration of microfilament organization, indicating that restoration of one of the diminished TM isoforms results in reorganization of microfilament bundles. However, no significant decrease in cell growth rate and the ability to grow in soft agar was observed in the TM2 cDNA-transduced cells.