title: Spontaneous calcium transients are required for neuronal differentiation of murine neural crest.
abstract: We have shown that cultured mouse neural crest (NC) cells exhibit transient increases in intracellular calcium. Up to 50% of the cultured NC-derived cells exhibited calcium transients during the period of neuronal differentiation. As neurogenic activity declined, so did the percentage of active NC-derived cells and their calcium spiking frequency. The decrease in calcium transient activity correlated with a decreased sensitivity to thimerosal, which sensitizes inositol 1,4,5-triphosphate receptors. Thimerosal increased the frequency of oscillations in active NC-derived cells and induced them in a subpopulation of quiescent cells. As neurogenesis ended, NC-derived cells became nonresponsive to thimerosal. Using the expression of time-dependent neuronal traits, we determined that neurons exhibited spontaneous calcium transients as early as a neuronal phenotype could be detected and continued through the acquisition of caffeine sensitivity, soon after which calcium transient activity stopped. A subpopulation of nonneuronal NC-derived cells exhibited calcium transient activity within the same time frame as neurogenesis in culture. Exposing NC-derived cells to 20 mM Mg(2+) blocked calcium transient activity and reduced neuronal number without affecting the survival of differentiated neurons. Using lineage-tracing analysis, we found that 50% of active NC-derived cells gave rise to clones containing neurons, while inactive cells did not. We hypothesize that calcium transient activity establishes a neuronal competence for undifferentiated NC cells.
authors.affiliation: Department of Biological Structure and Function, Oregon Health Sciences University, Portland, Oregon 97201, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Carey
authors.forename: S G
authors.initials: SG
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D009432:Neural Crest / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011247:Pregnancy; D013849:Thimerosal / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D013849:Thimerosal; D008274:Magnesium; D002118:Calcium