Richani Dulama, Sutton-McDowall Melanie L, Frank Laura A, Gilchrist Robert B, Thompson Jeremy G
Research Centre for Reproductive Health, Discipline of Obstetrics and Gynaecology, The Robinson Institute, School of Paediatrics and Reproductive Health, The University of Adelaide, Adelaide, South Australia, Australia.
Biol Reprod. 2014 Mar 6;90(3):49. doi: 10.1095/biolreprod.113.115311. Print 2014 Mar.
Oocyte in vitro maturation (IVM) is an assisted reproductive technology that involves the maturation of cumulus-oocyte complexes (COCs) that are then capable of normal development. We have shown that epidermal growth factor (EGF)-like peptide signaling is perturbed in mouse COCs undergoing IVM when matured with follicle-stimulating hormone (FSH) and/or EGF, but supplementation of IVM with EGF-like peptides amphiregulin or epiregulin improves oocyte developmental competence. Here we aimed to determine whether EGF-like peptides regulate COC metabolism. Immature 129/Sv mouse COCs underwent IVM with FSH, EGF, amphiregulin, epiregulin, betacellulin, or no treatment (control). Epiregulin significantly increased intraoocyte flavin adenine dinucleotide (FAD) and REDOX (reduction and oxidation) ratio compared to FSH and control. Amphiregulin and epiregulin significantly increased the proportion of J aggregates (from JC-1) in oocyte mitochondria compared to control, FSH, or EGF, and this coupled with FAD and REDOX measures indicates greater mitochondrial activity. There were no differences in glucose consumption, lactate production, or glycolysis between COCs matured with FSH, EGF, and EGF-like peptides. COCs matured with EGF or EGF-like peptides exhibited significantly higher mRNA expression of the hexosamine biosynthesis pathway (HBP) rate-limiting enzyme gene Gfpt2, Has2 expression, and global beta-O-linked glycosylation of proteins, compared to control or FSH, suggesting greater HBP activity. Our findings suggest that 1) EGF-like peptides, particularly epiregulin, induce more oocyte mitochondrial activity than EGF or FSH and 2) EGF-like peptides and EGF induce greater HBP activity, enabling more hyaluronic acid synthesis and protein beta-O-linked glycosylation. These metabolic alterations may be a mechanism by which EGF-like peptides increase oocyte developmental competence.
卵母细胞体外成熟（IVM）是一种辅助生殖技术，该技术涉及卵丘-卵母细胞复合体（COC）的成熟，使其随后能够正常发育。我们已经表明，当用促卵泡激素（FSH）和/或表皮生长因子（EGF）使小鼠COC在IVM过程中成熟时，表皮生长因子（EGF）样肽信号受到干扰，但用EGF样肽双调蛋白或表皮调节素补充IVM可提高卵母细胞的发育能力。在这里，我们旨在确定EGF样肽是否调节COC代谢。未成熟的129/Sv小鼠COC用FSH、EGF、双调蛋白、表皮调节素、β细胞素处理或不处理（对照）进行IVM。与FSH和对照相比，表皮调节素显著增加了卵母细胞内黄素腺嘌呤二核苷酸（FAD）和氧化还原（还原和氧化）比率。与对照、FSH或EGF相比，双调蛋白和表皮调节素显著增加了卵母细胞线粒体中J聚集体（来自JC-1）的比例；这与FAD和氧化还原测量结果相结合表明线粒体活性更高。在用FSH、EGF和EGF样肽成熟的COC之间，葡萄糖消耗、乳酸产生或糖酵解没有差异。与对照或FSH相比，用EGF或EGF样肽成熟的COC表现出己糖胺生物合成途径（HBP）限速酶基因Gfpt2的mRNA表达、Has2表达以及蛋白质的整体β-O-连接糖基化显著更高，表明HBP活性更高。我们的研究结果表明：1）EGF样肽，特别是表皮调节素，比EGF或FSH诱导更多的卵母细胞线粒体活性；2）EGF样肽和EGF诱导更高的HBP活性，从而实现更多的透明质酸合成和蛋白质β-O-连接糖基化。这些代谢改变可能是EGF样肽提高卵母细胞发育能力的一种机制。
