Desensitization of IP3‐induced Ca2+ release by overexpression of a constitutively active Gqα protein converts ventral to dorsal fate in Xenopus early embryos

• Published in: Development, growth & differentiation Vol. 42; no. 4; pp. 327 - 335
• Main Authors: Kume, Shoen, Saneyoshi, Takeo, Mikoshiba, Katsuhiko
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Science Pty 01.08.2000
• Subjects: 5‐trisphosphate receptor; Ca2; downregulation; inositol 1; Xenopus
• ISSN: 0012-1592; 1440-169X
• DOI: 10.1046/j.1440-169x.2000.00519.x

The constitutively active Gqα mutant construct (GqαQ‐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 GqαQ‐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.