Gap Junctions and the Regulation of Cellular Functions of Stem Cells during Development and Differentiation

In multicellular organisms, the role of gap junction intercellular communication (GJIC) in the regulation of cell proliferation, cell differentiation, and apoptosis is becoming increasingly recognized as one of the major cellular functions from the start of the fertilized egg, through normal development of the embryo and fetus, to the sexual maturation of the adult and ultimately to the maintenance of health of the aging adult. Given that the function of this membrane-associated protein channel is to synchronize electrotonic or metabolic functions, differential regulation of function at the transcriptional, translational, and posttranslational levels of a family of highly evolutionarily conserved genes (connexins) needs to be considered. Both inherited mutations and environmental modulation of GJIC could, in principle, affect the function of gap junctions to control cell proliferation, cell differentiation, and apoptosis, thereby leading to a wide variety of pathologies. We review a few techniques used to characterize the ability of stem and progenitor cells to perform GJIC.