Early migratory rat neural crest cells express functional gap junctions: Evidence that neural crest cell survival requires gap junction function

Gap junctions mediate crucial intercellular interactions during development . This study provides evidence that early migrating rat neural crest cells assemble functional gap junctions, as demonstrated by dye transfer followin g microinjection of single cells, which were phenotypically identified as n eural crest cells by their expression of the low- affinity nerve growth fac tor receptor. An immunohistochemical analysis using connexin- specific anti bodies revealed that migrating rat neural crest cells express the gap junct ion constituents connexins 43 (Cx 43) and Ox 46, We tested the hypothesis t hat gap junctions play an important role during early neural crest cell dev elopment by perturbing their function in migrating neural crest cells. Our data show that markedly decreasing gap junction communication between these neural crest cells in vitro with either 18 alpha-glycyrrhetinic acid or an andamide decreases their survival, whereas oleamide, a less effective block er of connexon function, had quantitatively less effect on neural crest cel l death. This cell death was associated with the occurrence of DNA nicking as detected by the terminal deoxynucleotidyl transferase (TdT)-mediated dUT P-biotin nick end-labelling (TUNEL) procedure, suggesting cell death via ap optosis, The effect of 18 alpha-glycyrrhetinic acid and anandamide on neura l crest cell survival was reversible and was not mimicked by the structural ly related compounds glycyrrhizic acid and palmitoylethanolamide, respectiv ely, which do not uncouple cells. These results indicate that gap junctions are necessary for the survival of spinal neural crest cells. (C) 2000 Wile y-Liss, Inc.