Ryan K E, Casey S M, Canty M J, Crowe M A, Martin F, Evans A C O
School of Agriculture, Food Science and Veterinary Medicine, College of Life Science, Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
Reproduction. 2007 Mar;133(3):617-26. doi: 10.1530/REP-06-0130.
Dominant follicles are those that continue to develop and have the potential to ovulate while subordinate follicles regress. Characteristics of dominant follicles include a larger diameter, higher intrafollicular estradiol, and lower IGF-binding protein (IGFBP)-4 concentrations compared with other cohort follicles. Follicle development is regulated by endocrine hormones that act via intracellular signaling pathways. Here, we show the differences in Akt, Erk, c-Jun N-terminal protein kinase, and p-38 signaling pathways between dominant and subordinate follicles at the dominance stage of the follicle wave. However, earlier in the follicle wave (dominant follicle selection), there were only differences in the levels of Akt and Erk signal transduction proteins among dominant and subordinate follicles. Using this profile of Akt and Erk protein expression in granulosa and theca cells of selected dominant follicles compared with subordinate follicles, we suggest a predictive model to identify future dominant and subordinate follicles from the pool of otherwise similar cohort follicles at the time of follicle wave emergence. We conclude that the Erk and Akt signal transduction pathways are important for dominant follicle selection and development and, furthermore, that the observed differences in these pathways mark the future dominant follicle from subordinate follicles before differences in follicular diameter, follicular fluid estradiol, and IGFBP-4 concentrations are apparent.
优势卵泡是指那些持续发育并具有排卵潜力的卵泡，而从属卵泡则会退化。与其他同期卵泡相比，优势卵泡的特征包括直径更大、卵泡内雌二醇水平更高以及胰岛素样生长因子结合蛋白（IGFBP）-4浓度更低。卵泡发育受通过细胞内信号通路起作用的内分泌激素调节。在此，我们展示了在卵泡波优势期优势卵泡和从属卵泡之间Akt、Erk、c-Jun氨基末端蛋白激酶和p-38信号通路的差异。然而，在卵泡波更早阶段（优势卵泡选择期），优势卵泡和从属卵泡之间仅在Akt和Erk信号转导蛋白水平上存在差异。通过比较所选优势卵泡与从属卵泡的颗粒细胞和卵泡膜细胞中Akt和Erk蛋白表达情况，我们提出了一个预测模型，用于在卵泡波出现时从其他相似的同期卵泡池中识别未来的优势卵泡和从属卵泡。我们得出结论，Erk和Akt信号转导通路对优势卵泡的选择和发育很重要，此外，在卵泡直径、卵泡液雌二醇和IGFBP-4浓度出现明显差异之前，这些通路中观察到的差异就已将未来的优势卵泡与从属卵泡区分开来。
