Peters Alexandra E, Caban Shandelle J, McLaughlin Eileen A, Roman Shaun D, Bromfield Elizabeth G, Nixon Brett, Sutherland Jessie M
Priority Research Centre for Reproductive Science, Schools of Biomedical Science & Pharmacy and Environmental & Life Sciences, University of Newcastle, Callaghan, NSW, Australia.
Pregnancy and Reproduction Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.
Front Cell Dev Biol. 2021 Jun 29;9:691826. doi: 10.3389/fcell.2021.691826. eCollection 2021.
Accompanying the precipitous age-related decline in human female fertility is an increase in the proportion of poor-quality oocytes within the ovary. The macroautophagy pathway, an essential protein degradation mechanism responsible for maintaining cell health, has not yet been thoroughly investigated in this phenomenon. The aim of this study was to characterize the macroautophagy pathway in an established mouse model of oocyte aging using in-depth image analysis-based methods and to determine mechanisms that account for the observed changes. Three autophagy pathway markers were selected for assessment of gene and protein expression in this model: Beclin 1; an initiator of autophagosome formation, Microtubule-associated protein 1 light chain 3B; a constituent of the autophagosome membrane, and lysosomal-associated membrane protein 1; a constituent of the lysosome membrane. Through quantitative image analysis of immunolabeled oocytes, this study revealed impairment of the macroautophagy pathway in the aged oocyte with an attenuation of both autophagosome and lysosome number. Additionally, an accumulation of amphisomes greater than 10 μm in area were observed in aging oocytes, and this accumulation was mimicked in oocytes treated with lysosomal inhibitor chloroquine. Overall, these findings implicate lysosomal dysfunction as a prominent mechanism by which these age-related changes may occur and highlight the importance of macroautophagy in maintaining mouse pre-ovulatory oocyte quality. This provides a basis for further investigation of dysfunctional autophagy in poor oocyte quality and for the development of therapeutic or preventative strategies to aid in the maintenance of pre-ovulatory oocyte health.
随着人类女性生育能力与年龄相关的急剧下降,卵巢内低质量卵母细胞的比例增加。巨自噬途径是一种负责维持细胞健康的重要蛋白质降解机制,在这一现象中尚未得到充分研究。本研究的目的是使用基于深入图像分析的方法,在已建立的卵母细胞衰老小鼠模型中表征巨自噬途径,并确定解释观察到的变化的机制。选择了三种自噬途径标志物来评估该模型中的基因和蛋白质表达:Beclin 1,自噬体形成的启动子;微管相关蛋白1轻链3B,自噬体膜的组成成分;溶酶体相关膜蛋白1,溶酶体膜的组成成分。通过对免疫标记卵母细胞的定量图像分析,本研究揭示了衰老卵母细胞中巨自噬途径的损伤,自噬体和溶酶体数量均减少。此外,在衰老卵母细胞中观察到面积大于10μm的两性体积累,在用溶酶体抑制剂氯喹处理的卵母细胞中也出现了这种积累。总体而言,这些发现表明溶酶体功能障碍是这些与年龄相关变化可能发生的一个突出机制,并突出了巨自噬在维持小鼠排卵前卵母细胞质量中的重要性。这为进一步研究卵母细胞质量差时自噬功能障碍以及开发有助于维持排卵前卵母细胞健康的治疗或预防策略提供了基础。