The involvement of inositol phosphoglycan mediators in the modulation of steroidogenesis by insulin and insulin-like growth factor-I

Endocrinology
G RomeroJ D Veldhuis

Abstract

We have investigated the mechanisms by which insulin and insulin-like growth factor-I (IGF-I) regulate the synthesis of progesterone by swine ovary granulosa cells. Analysis of the cell density dependence of the effects of insulin and IGF-I showed that the induction of progesterone synthesis by these growth factors is consistent with an autocrine or paracrine model of action, which involves the insulin- and IGF-I-stimulated release of a soluble factor(s) into the culture medium. We have tested the hypothesis that this soluble factor(s) may be structurally related to inositol phosphoglycans, a class of putative second messengers of the action of insulin. Consistent with this hypothesis, we isolated an activator of pyruvate dehydrogenase (PDH) phosphatase from culture medium obtained from cells treated with insulin or IGF-I. Further analysis showed that specific antibodies raised against the inositol phosphoglycan anchor of the variant surface glycoprotein of Trypanosoma brucei blocked the activation of PDH phosphatase by the material isolated from the culture medium, suggesting a close structural relationship between this putative PDH phosphatase activator and inositol phosphaglycans. Pertussis toxin treatment, shown to inhibit ...Continue Reading

Citations

Dec 31, 2005·Journal of Reproductive Immunology·M A PaineT W Rademacher
May 10, 2015·Molecular and Cellular Endocrinology·Katsumi TodaToshiji Saibara
Jun 15, 2013·Biochimie·Marine L Croze, Christophe O Soulage
Feb 10, 2004·Biology of Reproduction·Gongqiao Zhang, Johannes D Veldhuis
Aug 23, 2020·Biomedicines·Antonio J López-GamberoFernando Rodríguez de Fonseca
Apr 17, 1997·Biochemical and Biophysical Research Communications·D R JonesI Varela-Nieto

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