Desensitization of IP sub(3)-induced Ca super(2+) release by overexpression of a constitutively active Gq alpha 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: 01.08.2000
• Subjects: Xenopus
• ISSN: 0012-1592

The constitutively active Gq alpha mutant construct (Gq alpha Q-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 (IP sub(3))-Ca super(2+) signaling by overexpression of Gq alpha Q-L led to desensitization of IP sub(3)-induced Ca super(2+) 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 IP sub(3) receptor, as reported previously. These results strengthen the earlier finding that active IP sub(3)-Ca super(2+) signaling functions in ventral signaling during the early embryonic development of Xenopus. Furthermore, the nature of downregulation of the Xenopus IP sub(3) receptor through continuous stimulation of IP sub(3)-Ca super(2+) signaling might play a role in regulating endogenous IP sub(3)-Ca super(2+) signaling in Xenopus early development.