CELLULAR RAS PARTLY MEDIATES GAP JUNCTION CLOSURE BY THE POLYOMA-VIRUS MIDDLE TUMOR-ANTIGEN

Endogenous, cellular Ras proteins (c-Ras) mediate the transforming act ion of the polyoma virus middle Tumor antigen (mT), which is accompani ed by elimination of gap junctional, intercellular communication (GJIC ). In this report we show that reducing the c-Ras content of murine C3 H10T1/2 fibroblasts (10T1/2) through the expression of an anti-sense r as gene, increased GJIC by 60-80%. mT totally eliminated GJIC in norma l 10T1/2 cells but it reduced GJIC no more than 50% in the c-Ras defic ient lines. These results indicate that endogenous c-Ras is at least p artly responsible for the mT-induced gap junction closure.