IGF-1 receptors in Xenopus laevis ovarian follicle cells support the oocyte maturation response

Biology of Reproduction
S E SadlerMichelle Dsouza

Abstract

Insulin-like growth factor 1 (IGF-1)-stimulated amphibian oocyte maturation has been studied extensively by a number of laboratory groups, but in previous studies possible effects of IGF-1 on ovarian follicle cells had not been tested directly. In the study reported here, biochemical and immunofluorescent techniques were used to test Xenopus ovarian follicle cells for the presence of hormone-sensitive IGF-1 receptor. Anti-xIGF-1 receptor beta-subunit antibodies detected a 90- and 98-kDa protein doublet in manually dissected oocyte cortices (plasma membrane-vitelline envelope complexes) by protein immunoblotting both before and after removal of follicle cells from oocytes by sandpaper rolling. The 90-kDa IGF-1 receptor beta-subunit was also detected in follicle cell pellets. Tyrosine phosphorylation of the receptor beta-subunits was increased by treatment of cortices with 10 nM IGF-1 both in the presence and absence of associated follicle cells, was reduced by removal of follicle cells, and was detected in follicle cell pellets. Treatment of follicle cell pellets with nanomolar concentrations of IGF-1 stimulated receptor tyrosine phosphorylation in a dose-dependent fashion that correlated with dose-dependent stimulation of oocyt...Continue Reading

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Methods Mentioned

BETA
electrophoresis
light microscopy
glycosylation

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Slidebook
BLAST

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