Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/83268
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Type: | Journal article |
Title: | Hyperglycaemic conditions perturb mouse oocyte in vitro developmental competence via beta-O-linked glycosylation of Heat shock protein 90 |
Author: | Frank, L. Sutton-McDowall, M. Brown, H. Russell, D. Gilchrist, R. Thompson, J. |
Citation: | Human Reproduction, 2014; 29(6):1292-1303 |
Publisher: | Oxford University Press |
Issue Date: | 2014 |
ISSN: | 0268-1161 1460-2350 |
Organisation: | Robinson Institute |
Statement of Responsibility: | L.A. Frank, M.L. Sutton-McDowall, H.M. Brown, D.L. Russell, R.B. Gilchrist, and J.G. Thompson |
Abstract: | STUDY QUESTION What is the effect of beta-O-linked glycosylation (O-GlcNAcylation) on specific proteins in the cumulus-oocyte complex (COC) under hyperglycaemic conditions? SUMMARY ANSWER Heat shock protein 90 (HSP90) was identified and confirmed as being O-GlcNAcylated in mouse COCs under hyperglycaemic conditions (modelled using glucosamine), causing detrimental outcomes for embryo development. WHAT IS KNOWN ALREADY O-GlcNAcylation of proteins occurs as a result of increased activity of the hexosamine biosynthesis pathway, which provides substrates for cumulus matrix production during COC maturation, and also for O-GlcNAcylation. COCs matured under hyperglycaemic conditions have decreased developmental competence, mediated at least in part through the mechanism of increased O-GlcNAcylation. STUDY DESIGN, SIZE, DURATION This study was designed to examine the effect of hyperglycaemic conditions (using the hyperglycaemic mimetic, glucosamine) on O-GlcNAc levels in the mouse COC, and furthermore to identify potential candidate proteins which are targets of this modification, and their roles in oocyte maturation. PARTICIPANTS/MATERIALS, SETTING, METHODS COCs from 21-day-old superovulated CBA × C57BL6 F1 hybrid female mice were matured in vitro (IVM). Levels of O-GlcNAcylated proteins, HSP90 and O-GlcNAc transferase (OGT, the enzyme responsible for O-GlcNAcylation) in COCs were measured using western blot, and localization observed using immunocytochemistry. For glycosylated HSP90 levels, and to test OGT-HSP90 interaction, immunoprecipitation was performed prior to western blotting. Embryo development was assessed using in vitro fertilization and embryo culture post-maturation. MAIN RESULTS AND THE ROLE OF CHANCE Addition of the hyperglycaemic mimetic glucosamine to IVM medium for mouse COCs increased detectable O-GlcNAcylated protein levels (by western blot and immunocytochemistry), and this effect was reversed using an OGT inhibitor (P < 0.05). HSP90 was identified as a target of O-GlcNAcylation in the COC, and inhibition of HSP90 during IVM reversed glucosamine-induced decreases in oocyte developmental competence (P < 0.05). We also demonstrated the novel finding of an association between HSP90 and OGT in COCs, suggesting a possible client–chaperone relationship. LIMITATIONS, REASONS FOR CAUTION In vitro maturation of COCs was used so that treatment time could be limited to the 17 h of maturation prior to ovulation. Additionally, glucosamine, a hyperglycaemic mimetic, was used because it specifically activates the hexosamine pathway which provides the O-GlcNAc moieties. The results in this study should be confirmed using in vivo models of hyperglycaemia and different HSP90 inhibitors. WIDER IMPLICATIONS OF THE FINDINGS This study leads to a new understanding of how diabetes influences oocyte competence and provides insight into possible therapeutic interventions based on inhibiting HSP90 to improve oocyte quality. |
Keywords: | Hyperglycaemia oocyte developmental competence hexosamine pathway HSP90 O-GlcNAc |
Rights: | © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com |
DOI: | 10.1093/humrep/deu066 |
Grant ID: | http://purl.org/au-research/grants/nhmrc/453556 |
Published version: | http://dx.doi.org/10.1093/humrep/deu066 |
Appears in Collections: | Aurora harvest 4 Obstetrics and Gynaecology publications |
Files in This Item:
File | Description | Size | Format | |
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hdl_83268.pdf | Accepted version | 1.58 MB | Adobe PDF | View/Open |
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