Infertility Clinic, Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Biol Reprod. 2011 Sep;85(3):465-72. doi: 10.1095/biolreprod.111.091314. Epub 2011 May 18.
Autophagy is associated with luteal cells death during regression of the corpus luteum (CL) in some species. However, the involvement of autophagy or the association between autophagy and apoptosis in CL regression are largely unknown. Therefore, we investigated the role of autophagy in CL regression and its association with apoptosis. Ovaries were obtained from pseudopregnant rats at Days 2 (early), 7 (mid-), and 14 and 20 (late-luteal stage) of the pseudopregnancy; autophagy-associated protein (microtuble-associated protein light chain 3 [LC3]) was immunolocalized and its expression level was measured. Luteal cell apoptosis was evaluated by measuring cleaved caspase 3 expression. LC3 expression increased slightly from early to mid-luteal stage, with maximal levels detected at the late-luteal stage in steroidogenic luteal cells. The expression level of the membrane form of LC3 (LC3-II) also increased during luteal stage progression, and reached a maximum at the end point of late-luteal stage (Day 20). This pattern coincided with cleaved caspase 3 expression. Furthermore, LC3-II expression increased, as did levels of cleaved caspase 3 in luteal cells cultured with prostaglandin F(2alpha) known to induce CL regression. These findings suggest that luteal cell autophagy is directly involved in CL regression, and is correlated with increased apoptosis. In addition, autophagic processes were inhibited using 3-methyladenine or bafilomycin A1 to evaluate the role of autophagy in apoptosis induction. Inhibition of autophagosome degradation by fusion with lysosomes (bafilomycin A1) increased apoptosis and cell death. Furthermore, inhibition of autophagosome formation (3-methyladenine) decreased apoptosis and cell death, suggesting that the accumulation of autophagosomes induces luteal cell apoptosis. In conclusion, these results indicate that autophagy is involved in rat luteal cell death through apoptosis, and is most prominent during CL regression.
自噬与黄体细胞死亡有关，在一些物种的黄体退化期间。然而，自噬的参与或自噬与黄体退化中的细胞凋亡之间的关联在很大程度上尚不清楚。因此，我们研究了自噬在黄体退化中的作用及其与细胞凋亡的关系。从假孕大鼠的卵巢中获得在假孕第 2 天（早期）、第 7 天（中期）、第 14 天和第 20 天（黄体晚期）获得；用免疫组织化学方法定位自噬相关蛋白（微管相关蛋白轻链 3 [LC3]）并测量其表达水平。通过测量裂解的半胱氨酸蛋白酶 3 的表达来评估黄体细胞凋亡。LC3 的表达从早期到中期黄体阶段略有增加，在甾体生成黄体细胞中晚期黄体阶段达到最高水平。LC3 的膜形式（LC3-II）的表达水平在黄体阶段进展过程中也增加，并在晚期黄体阶段的终点（第 20 天）达到最大值。这种模式与裂解的半胱氨酸蛋白酶 3 的表达一致。此外，在已知诱导黄体退化的前列腺素 F(2alpha)培养的黄体细胞中，LC3-II 的表达增加，同时裂解的半胱氨酸蛋白酶 3 的水平也增加。这些发现表明黄体细胞自噬直接参与黄体退化，并与凋亡增加有关。此外，使用 3-甲基腺嘌呤或巴弗洛霉素 A1 抑制自噬体降解来评估自噬在诱导细胞凋亡中的作用。通过与溶酶体融合抑制自噬体降解（巴弗洛霉素 A1）增加了凋亡和细胞死亡。此外，抑制自噬体形成（3-甲基腺嘌呤）减少了凋亡和细胞死亡，表明自噬体的积累诱导黄体细胞凋亡。总之，这些结果表明，自噬通过细胞凋亡参与大鼠黄体细胞死亡，在黄体退化期间最为明显。
