Molecular cloning and characterization of Xenopus insulin-like growth factor-1 receptor: its role in mediating insulin-induced Xenopus oocyte maturation and expression during embryogenesis.
We have cloned a complementary DNA encoding the putative Xenopus insulin-like growth factor-1 (xIGF-1) receptor. Injection of messenger RNA derived from the cloned complementary DNA into Xenopus oocytes resulted in the expression and correct processing of the receptor's alpha- and 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 concentrations of mammalian IGF-1 and by insulin approximately 100-fold higher in concentration. This receptor activation profile correlated with hormone-induced Xenopus oocyte maturation. Furthermore, injection of a neutralizing antiinsulin receptor antibody into Xenopus oocytes inhibited hormone-induced xIGF-1 receptor activation. These results provide molecular and biochemical evidence supporting a role for xIGF-1 receptor in mediating insulin/IGF-1-induced Xenopus oocyte maturation. We also report here that embryonic transcription of xIGF-1 receptor is activated during the formation of the central nervous system in early Xenopus embryos.
Zhu
L
L
Ottawa Civic Hospital Loeb Research Institute, Canada.
Ohan
N
N
Agazie
Y
Y
Cummings
C
C
Farah
S
S
Liu
X J
XJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D007328:Insulin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology; D017526:Receptor, IGF Type 1 / Q000235:genetics* / Q000502:physiology; D014981:Xenopus / Q000196:embryology*
D007328:Insulin; D017526:Receptor, IGF Type 1