title: Noggin upregulates Fos expression by a calcium-mediated pathway in amphibian embryos.
abstract: In amphibia, noggin, one of the neural inducers expressed in the Spemann organizer, acts by neutralizing the effects of bone morphogenetic protein-4 (BMP-4). It is shown that noggin is able to activate L-type calcium channels. The fos proto-oncogene is known to be induced within minutes by calcium signaling. Here it is reported that in animal cap explants of the amphibian Pleurodeles waltl, noggin can induce upregulation of a FOS-related protein in a calcium-dependent manner. Specific inhibition of the dihydropyridine sensitive L-type calcium channels blocked both calcium influx and the induction of FOS-related protein. When animal cap explants were treated with caffeine in order to release calcium from an internal store or with a specific agonist of the L-type calcium channels, FOS-related protein could be detected in cell nuclei by 5 or 15 min, respectively. Additionally, the calcium calmodulin kinase inhibitor. KN62, could block the upregulation of FOS-related protein induced by agents that increased intracellular calcium ([Ca2+]i). The present results suggest that transcription factors from the FOS family are downstream targets of neural inducer noggin.
authors.affiliation: Centre de Biologie du Développement, UMR 5547, Université Paul Sabatier, Toulouse, France.
authors.forename: C
authors.initials: C
authors.lastname: Leclerc
authors.forename: A M
authors.initials: AM
authors.lastname: Duprat
authors.forename: M
authors.initials: M
authors.lastname: Moreau
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D015220:Calcium Channels / Q000494:pharmacology; D020746:Calcium Channels, L-Type; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins; D003208:Concanavalin A / Q000494:pharmacology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004789:Enzyme Activation; D018613:Microscopy, Confocal; D010999:Pleurodeles / Q000196:embryology*; D011506:Proteins / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology*; D000099176:Noggin Protein
chemical_list: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002118:Calcium; D002120:Calcium Channel Agonists; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins; D003208:Concanavalin A; D011506:Proteins; D016760:Proto-Oncogene Proteins c-fos; D000099176:Noggin Protein