Interaction of the IP(3)-Ca(2+) and the FGF-MAPK signaling pathways in the Xenopus laevis embryo: a qualitative approach to the mesodermal induction problem.
In this work we propose that the animal-vegetal gradient spatial distribution of the IP(3) receptors observed in the Xenopus embryo can effect a uniform FGF inducting input signal, allowing for different modes of transcription of the Xbra gene, producing the differentiation of the cells of the marginal zone. We analyze this hypothesis with a model for the interaction of the calcium signaling system with the MAPK cascade during the FGF mesodermal induction process, consisting of five non-linear coupled differential equations. A numerical treatment of a one- and two-cell system shows that the calcium flux between cells enhances the Raf activity levels, leading to oscillatory behavior. This qualitative result may be of consequence for the expression of the ventralizing characteristics of the FGF inducting signal.
Díaz
José
J
Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos, Mexico C.P. 62210. jdiaz@fis.unam.mx
Baier
Gerold
G
Martínez-Mekler
Gustavo
G
Pastor
Nina
N
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction / Q000235:genetics / Q000502:physiology*; D004789:Enzyme Activation; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D053496:Inositol 1,4,5-Trisphosphate Receptors; D020935:MAP Kinase Signaling System; D008648:Mesoderm / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D017468:Receptors, Fibroblast Growth Factor; D005346:Fibroblast Growth Factors; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium