Gap junctions and synchronization of polarization process during epithelial reorganization

The formation of intercellular communication during epithelial reorganization of LLC-PK1 cells was studied with a new, nondisruptive flow cytometric technique. The assembly of these junctions, as demonstrated by cell-to-cell transfer of the fluorescent dye carboxy dimethyl fluorescein, occurs very early during epithelial reorganization. Close cell-to-cell interaction is required for the assembly to occur. Low temperature, treatment with 10(-3) M ouabain, or treatment with the Ca2+ ionophore A23187 inhibits assembly of these junctions. Removal of Ca2+ from the incubation medium, on the other hand, has no effect. Cycloheximide (10(-6) M) is also without effect, suggesting that protein synthesis is not required during the assembly of the junctions and that either the trypsin used to disperse the cells does not affect the junctional components or the cells have a rather extensive reserve pool of junctional precursors. The concomitant delay in the development of intercellular communication and the reorganization of the epithelial membrane, as previously observed with cells in asynchronous growth [Am. J. Physiol. 251 (Renal Fluid Electrolyte Physiol. 20): F978-F987, 1986], is consistent with the theory that junctional intercellular communication coordinates cellular activity during epithelial reorganization.