Connexin 43 Regulates Multiple Aspects of Chick Cranial Neural Crest Cell Development

Abstract

Connexins are transmembrane proteins that cluster to form intercellular channels called gap junctions, which allow direct diffusion of small molecules and ions between adjacent cells. 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 perturbation experiments to alter the levels of Cx43 in both premigratory and migratory neural crest cells. Our fixed and live imaging results reveal that gap junction formation occurs within both the premigratory and migratory neural crest cell populations. Moreover, morpholino‐mediated reduction in Cx43 protein levels prevents neural crest cells from forming functional gap junctions, as assessed by live imaging of transfer of the gap junction‐specific dye Calcein in the embryo. Additionally, depletion of Cx43 from premigratory neural crest cells reduces the size of the premigratory neural crest cell domain and also delays the emergence of neural crest cells from the dorsal neural tube. This delayed neural tube exit phenotype can be rescued by introduction of full‐length rat Cx43 that is refractory to the morpholino. These data suggest that gap junctions, and Cx43 in particular, are involved in early neural crest cell specification and in the emergence of neural crest cells from the neural tube.Support or Funding InformationThe work was supported by an American Association for Anatomy Postdoctoral Fellowship to K.J. and grants to L.A.T. (NIH R01DE024217, American Cancer Society RSG‐15‐023‐01‐CSM).