MOLECULAR-CLONING AND CHARACTERIZATION OF XENOPUS INSULIN-LIKE GROWTH-FACTOR-I RECEPTOR - ITS ROLE IN MEDIATING INSULIN-INDUCED XENOPUS OOCYTE MATURATION AND EXPRESSION DURING EMBRYOGENESIS
L. Zhu et al., MOLECULAR-CLONING AND CHARACTERIZATION OF XENOPUS INSULIN-LIKE GROWTH-FACTOR-I RECEPTOR - ITS ROLE IN MEDIATING INSULIN-INDUCED XENOPUS OOCYTE MATURATION AND EXPRESSION DURING EMBRYOGENESIS, Endocrinology, 139(3), 1998, pp. 949-954
We have cloned a complementary DNA encoding the putative Xenopus insul
in-like growth factor-1 (xIGF-1) receptor. Injection of messenger RNA
derived from the cloned complementary DNA into Xenopus oocytes resulte
d in the expression and correct processing of the receptor's alpha- an
d beta-subunits. Using antibodies generated against protein expressed
against the cloned sequence, we demonstrated that the endogenous xIGF-
1 receptor in Xenopus oocytes was activated by nanomolar concentration
s of mammalian IGF-1 and by insulin approximately 100-fold higher in c
oncentration. This receptor activation profile correlated with hormone
-induced Xenopus oocyte maturation. Furthermore, injection of a neutra
lizing antiinsulin receptor antibody into Xenopus oocytes inhibited ho
rmone-induced xIGF-1 receptor activation. These results provide molecu
lar and biochemical evidence supporting a role for xIGF-1 receptor in
mediating insulin/IGF-1-induced Xenopus oocyte maturation. We also rep
ort here that embryonic transcription of xIGF-1 receptor is activated
during the formation of the central nervous system in early Xenopus em
bryos.