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Article
Inhibition of PIK3 Signaling Pathway Members by the Ovotoxicant 4-Vinylcyclohexene Diepoxide in Rats
Biology of Reproduction
  • Aileen F. Keating, Iowa State University
  • Shannon M. Fernandez, University of Arizona
  • Connie J. Mark-Kappeler, University of Arizona
  • Nivedita Sen, University of Arizona
  • I. Glenn Sipes, Univeresity of Arizona
  • Patricia B. Hoyer, University of Arizona
Document Type
Article
Publication Version
Published Version
Publication Date
4-1-2011
DOI
10.1095/biolreprod.110.087650
Abstract

4-Vinylcyclohexene diepoxide (VCD), an occupational chemical that specifically destroys primordial and small primary follicles in the ovaries of rats and mice, is thought to target an oocyte-expressed tyrosine kinase receptor, Kit. This study compared the temporal effect of VCD on protein distribution of KIT and its downstream PIK3-activated proteins, AKT and FOXO3. Postnatal Day 4 Fischer 344 rat ovaries were cultured in control media ± VCD (30 μM) for 2–8 days (d2–d8). KIT, AKT, phosphorylated AKT, FOXO3, and pFOXO3 protein levels were assessed by Western blotting and/or immunofluorescence staining with confocal microscopy. Phosphorylated AKT was decreased (P < 0.05) in oocyte nuclei in primordial (39% decrease) and small primary (37% decrease) follicles within 2 days of VCD exposure. After d4, VCD reduced (P < 0.05) oocyte staining for KIT (primordial, 44% decrease; small primary, 39% decrease) and FOXO3 (primordial, 40% decrease; small primary, 36% decrease) protein. Total AKT and pFOXO3 were not affected by VCD at any time. Akt1 mRNA, as measured by quantitative RT-PCR, was reduced (P < 0.05) by 23% on d4 of VCD exposure, but returned to control levels on d6 and d8. VCD exposure reduced Foxo3amRNA by 26% on d6 (P < 0.05) and by 23% on d8 (P < 0.1). These results demonstrate that the earliest observed effect of VCD is an inhibition of phosphorylation and nuclear localization of AKT in the oocyte of primordial and small primary follicles. This event is followed by reductions in KIT and FOXO3 protein subcellular distribution prior to changes in mRNA. Thus, these findings further support that VCD induces ovotoxicity by directly targeting the oocyte through posttranslational inhibition of KIT-mediated signaling components.

Comments

This article is published as Keating, Aileen F., Shannon M. Fernandez, Connie J. Mark-Kappeler, Nivedita Sen, I. Glenn Sipes, and Patricia B. Hoyer. "Inhibition of PIK3 signaling pathway members by the ovotoxicant 4-vinylcyclohexene diepoxide in rats." Biology of reproduction 84, no. 4 (2011): 743-751. doi: 10.1095/biolreprod.110.087650.

Creative Commons License
Creative Commons Attribution-Noncommercial 3.0
Copyright Owner
Society for the Study of Reproduction, Inc.
Language
en
File Format
application/pdf
Citation Information
Aileen F. Keating, Shannon M. Fernandez, Connie J. Mark-Kappeler, Nivedita Sen, et al.. "Inhibition of PIK3 Signaling Pathway Members by the Ovotoxicant 4-Vinylcyclohexene Diepoxide in Rats" Biology of Reproduction Vol. 84 Iss. 4 (2011) p. 743 - 751
Available at: http://works.bepress.com/aileen-keating/31/