A NOVEL TECHNIQUE FOR THE STUDY OF INTERCELLULAR, JUNCTIONAL COMMUNICATION - ELECTROPORATION OF ADHERENT CELLS ON A PARTLY CONDUCTIVE SLIDE

One of the effects of neoplastic transformation by a variety of factor s is a decrease in gap junctional, intercellular communication (GJIC). The investigation of junctional permeability is usually conducted thr ough the microinjection of the fluorescent dye, Lucifer yellow, follow ed by observation of its migration into neighboring cells. This is a t ime-consuming approach, requiring expensive equipment. To overcome the se problems, a novel technique was devised which takes advantage of th e ability of short electric pulses to create transient ''pores'' on th e cell membrane through which Lucifer yellow can enter, simultaneously and into large numbers of cells, with minimal disturbance to cellular metabolism. Cells were grown on a glass slide, half of which was coat ed with electrically conductive, optically transparent, indium-tin oxi de. An electric pulse was applied in the presence of Lucifer yellow, c ausing its penetration into the cells growing on the conductive half o f the slide, and the migration of the dye to the nonelectroporated cel ls growing on the nonconductive area was microscopically observed unde r fluorescence illumination. Using this technique, we investigated the relationship between expression of the middle turner antigen of polyo ma virus (mT) and GJIC in two representative cell systems with differe nt responses to mT. The results show that low mT expression levels, al though unable to transform rat F111 cells fully, are able to interrupt GJIC. Although parts of this mechanism might be mediated through prot ein kinase C (PKC), mT appears to have additional functions. PKC, howe ver, had the opposite effect upon junctional permeability in a clone o f mouse NIH-3T3 fibroblasts; intercellular communication in these cell s appears to require PKC activity.