Connexin 43 Function in the Cranial Neural Crest

Abstract

Connexins are transmembrane proteins that cluster to form intercellular channels called gap junctions, which function to allow direct diffusion of small molecules and ions between adjacent cells. Gap junctions are composed of two connexons (one on each cell which are docked head‐to‐head) consisting of either homomeric or heteromeric connexin proteins. Connexin 43 (Cx43) is one of the predominant components of gap junctions and is expressed in multiple organisms and their tissues. To date, however, very little is known about the role of gap junctions, and specifically Cx43, in the neural crest. Our prior immunohistochemical analyses revealed that Cx43 is expressed in premigratory cranial neural crest cells both prior to and during their epithelial‐to‐mesenchymal transition (EMT), and in migratory neural crest cells. Given the robust expression of Cx43 in premigratory neural crest cells, we sought to elucidate the role of Cx43, and gap junctions in particular, during neural crest cell EMT. To this end, we evaluated the presence of gap junctions in the neural crest and performed molecular and chemical perturbation experiments to alter Cx43 and general gap junction function. Our results reveal that gap junctions form between migratory neural crest cells, demonstrated in the embryo and in explants of premigratory neural crest tissue cultured ex vivo. Live‐imaging of embryos initially possessing Calcein‐AM (a dye that only traverses gap junctions) in a small number of premigratory neural crest cells demonstrates passage of dye to adjacent cells over time. Additionally, depletion of Cx43 from premigratory neural crest cells reveals changes in some neural crest cell molecular markers. In ex vivo explants, Cx43 knockdown in migratory neural crest cells precludes transfer of Calcein‐AM dye, and abrogation of gap junction function through chemical inhibition hinders neural crest cell EMT and/or migration. In future experiments, we will ascertain the effects of Cx43 knockdown and overexpression on neural crest cell EMT and migration in vivo by examining passage of Calcein‐AM dye to assess gap junction function and through immunohistochemistry to evaluate changes in neural crest cells. These data will provide insight into how neural crest cells interact and communicate during EMT and migration to allow for proper embryonic patterning throughout vertebrate development.Support or Funding InformationThe work was supported by grants to L.A.T. (NIH R01DE024217, American Cancer Society RSG‐15‐023‐01‐CSM).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.