VOLTAGE-DEPENDENT-L-TYPE CA2+ CHANNELS PARTICIPATE IN REGULATING NEURAL CREST MIGRATION AND DIFFERENTIATION

General models of cell activation implicate Ca2+ conductance as pivotal in conveying transmembrane signals. During embryonic development, both cell migration and differentiation are influenced by changes in Ca2+; and, as a consequence, the modulation of Ca2+ is important in the control of many morphogenetic processes. Because Ca2+ conductance may be regulated at voltage-dependent Ca2+ channels (VDCCs), we investigated whether neural crest cells develop VDCCs and, if so, whether they function in regulating migration and establishing cytomorphology. Autoradiography indicates that neural crest cells in vitro develop -L-type Ca2+ channels during migration and differentiation. Blockage of these channels by verapamil, both in vivo and in vitro, leads to a dramatic and reversible inhibition of neural crest migration. Alterations are manifest in vitro in cell-to-cell and cell-to-substratum contact and in the organization of the actin cytoskeleton. In whole embryos, verapamil or nifedipine inhibits pigment pattern formation. Moreover, blockage of the -L-type Ca2+ channels in whole embryos or cultures, after cells have already migrated and differentiated, results in a significant change in individual cell shape and in the overall pigment cell pattern, suggesting further that maintenance of the differentiated state also requires regulation at the -L-type Ca2+ channel. Since certain aspects of neural crest adhesion and cytoskeletal function are dependent on Ca2+, it is suggested that interactions that regulate the availability of Ca2+ through the VDCC may provide coordinate control of motile and adhesive interactions at the cell-substratum interface.