REGULATION OF JUNCTIONAL COMMUNICATION IN CULTURED-CELLS TRANSFECTED WITH THE CONNEXIN CX32 GENE

HeLa cells are widely used as recipients in transfection and stable ex pression of exogenous genes of connexins (Cx), proteins forming gap ju nction channels. We assessed the electric conduction of the junctions and the efficacy of cell diffusion coupling in HeLa cells transfected with the murine connexin Cx32 gene. Immunocytochemistry and freeze-fra cture electron microscopy demonstrated that these cells formed distinc t gap junctions. Although HeLa-Cx32 was a clonal cell line, the juncti onal conductance distribution pattern testified to the presence of sev eral cell subpopulations differing in the extent of cell coupling; thi s heterogeneity could be associated with the cell morphological types. The relative amount of cell with low and high junction conductance va ried with culture age and cell density. The average conductance was ma ximal after two days of culturing and declined by the fourth. In paral lel assays of the efficacy of intercell diffusion with the dye Lucifer Yellow, similar changes were found in the number of contacts with low and high permeability. These data could be considered as evidence for physiological regulation of the gap junction coupling in transfected cells.