title: Desensitization of IP3-induced Ca2+ release by overexpression of a constitutively active Gqalpha protein converts ventral to dorsal fate in Xenopus early embryos.
abstract: The constitutively active Gqalpha mutant construct (GqalphaQ-L) in Xenopus early embryos was overexpressed and the effects on dorsoventral patterning examined. It was found that prolonged stimulation of inositol 1,4,5-trisphosphate (IP3)-Ca2+ signaling by overexpression of GqalphaQ-L led to desensitization of IP3-induced Ca2+ release (IICR). Desensitization of IICR on the ventral side specifically induced an ectopic dorsal axis due to the conversion of ventral marginal mesoderm to adopt a dorsal fate. This effect of desensitization resembles that of inhibitory antibodies against the IP3 receptor, as reported previously. These results strengthen the earlier finding that active IP3-Ca2+ signaling functions in ventral signaling during the early embryonic development of Xenopus. Furthermore, the nature of downregulation of the Xenopus IP3 receptor through continuous stimulation of IP3-Ca2+ signaling might play a role in regulating endogenous IP3-Ca2+ signaling in Xenopus early development.
authors.affiliation: Mikoshiba Calciosignal Net Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Corporation, Tokyo. skume@ims.u-tokyo.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Kume
authors.forename: T
authors.initials: T
authors.lastname: Saneyoshi
authors.forename: K
authors.initials: K
authors.lastname: Mikoshiba
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019521:Body Patterning / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002352:Carrier Proteins; D017931:DNA Primers / Q000737:chemistry; D015536:Down-Regulation; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D038681:Follistatin; D016257:Fura-2 / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D006023:Glycoproteins / Q000378:metabolism; D006168:Guinea Pigs; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D036341:Intercellular Signaling Peptides and Proteins; D009865:Oocytes / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D012313:RNA / Q000032:analysis; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology*; D000099176:Noggin Protein
chemical_list: D002118:Calcium; D015220:Calcium Channels; D002352:Carrier Proteins; D017931:DNA Primers; D038681:Follistatin; D016257:Fura-2; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D006023:Glycoproteins; D020962:Heterotrimeric GTP-Binding Proteins; D018398:Homeodomain Proteins; D015544:Inositol 1,4,5-Trisphosphate; D053496:Inositol 1,4,5-Trisphosphate Receptors; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D012313:RNA; D018160:Receptors, Cytoplasmic and Nuclear; D029867:Xenopus Proteins; D000099176:Noggin Protein; C112507:ventx1.2 protein, Xenopus; C054234:chordin