title: Increased internal Ca2+ mediates neural induction in the amphibian embryo.
abstract: The molecular mechanism of neural induction is still unknown and the identity of the natural inducer remains elusive. It has been suggested that both the protein kinase C and cAMP signal transduction pathways may be involved in mediating its action. Here we provide evidence that Ca2+ is implicated in the process of transduction of the neuralizing signal. We find that an increase in intracellular Ca2+ concentration [Ca2+]i occurs during neural induction provoked in vitro by the lectin Con A in Pleurodeles waltl embryo. We demonstrate that specific L-type Ca2+ channel agonists also trigger neural induction. Conversely, noninducing lectins do not raise [Ca2+]i. Ryanodine and caffeine trigger neural induction. An increase in [Ca2+]i was also observed after treatment with the phorbol 12-myristate 13-acetate, which has been reported to be inductive. The [Ca2+]i increase triggered by phorbol ester and Con A was abolished by staurosporine and by L-type Ca2+ channel antagonists. Our findings demonstrate that the [Ca2+]i increase occurs via L-type Ca2+ channels. We suggest an amplification of this increase by a Ca(2+)-induced Ca2+ release mechanism which involves intracellular ryanodine-sensitive stores. We propose that Ca(2+)-dependent processes controlled by protein kinase C are implicated in the regulation of gene expression in response to neural induction.
authors: Centre de Biologie du Développement, Centre National de la Recherche Scientifique/Université Paul Sabatier, Toulouse, France.
authors: M
authors: M
authors: Moreau
authors: C
authors: C
authors: Leclerc
authors: L
authors: L
authors: Gualandris-Parisot
authors: A M
authors: AM
authors: Duprat
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004475:Ectoderm / Q000502:physiology; D004627:Embryonic Induction; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D017275:Isradipine / Q000494:pharmacology; D009420:Nervous System / Q000196:embryology*; D009553:Nimodipine / Q000494:pharmacology; D010999:Pleurodeles; D011493:Protein Kinase C / Q000502:physiology; D012433:Ryanodine / Q000494:pharmacology; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D015220:Calcium Channels; D003208:Concanavalin A; D012433:Ryanodine; D002110:Caffeine; D009553:Nimodipine; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D017275:Isradipine