Migrating cells retain gap junction plaque structure and function

Cell migration is an essential process in organ development, differentiation, and wound healing, and it has been hypothesized that gap junctions play a pivotal role in these cell processes. However, the changes in gap junctions and the capacity for cell communication as cells migrate are unclear. To monitor gap junction plaques during cell migration, adrenocortical cells were transfected with cDNA encoding for the connexin 43-green fluorescent protein. Time-lapse imaging was used to analyze cell movements and concurrent gap junction plaque dynamics. Immunocytochemistry was used to analyze gap junction morphology and distribution. Migration was initiated by wounding the cell monolayer and diffusional coupling was demonstrated by monitoring Lucifer yellow dye transfer and fluorescence recovery after photobleaching (FRAP) in cells at the wound edge and in cells located some distance from the wound edge. Gap junction plaques were retained at sites of contact while cells migrated in a "sheet-like" formation, even when cells dramatically changed their spatial relationship to one another. Consistent with this finding, cells at the leading edge retained their capacity to communicate with contacting cells. When cells detached from one another, gap junction plaques were internalized just prior to cell process detachment. Although gap junction plaque internalization clearly was a method of gap junction removal during cell separation, cells retained gap junction plaques and continued to communicate dye while migrating.