Laboratory of Reproductive Biology, School of Public Health, Chongqing Medical University, Chongqing, 400016, China.
Joint International Research Laboratory of Reproduction&Development, Chongqing, 400016, China.
J Mol Med (Berl). 2020 Apr;98(4):555-567. doi: 10.1007/s00109-019-01849-y. Epub 2020 Feb 18.
Embryo implantation is an essential and complex process in mammalian reproduction. However, little evidence has indicated the involvement of autophagy during embryo implantation. To determine the possible role of autophagy in uterine of pregnant mice during the peri-implantation stage, we first examined the expression of autophagy-related markers ATG5 and LC3 on day 4, 5, and 6 of pregnancy (D4, D5, and D6, respectively). Compared with expression on D4, downregulation of the autophagy-related markers was observed on D5 and D6, the days after the embryo attached to the receptivity endometrium. Further examination showed that autophagy-related markers ATG5, ATG12, LC3, cathepsin B, and P62 at the implantation site were significantly decreased when comparing with the inter-implantation site. Fewer number of autophagosomes at the implantation site were also observed by transmission electron microscopy. To confirm the functional role of autophagy during embryo implantation in mice, we administered the autophagy inhibitor 3-methyladenine and chloroquine to mice. After treated with 3-methyladenine, the expression of decidual markers HOXA10 and progesterone receptor were significantly reduced. Furthermore, a reduction in implantation sites and increase in the HOXA10 and PR protein levels were observed in response to chloroquine treatment. In addition, impaired uterine decidualization and dysregulation of the PR and HOXA10 protein levels was observed after autophagy inhibited by 3-methyladenine and chloroquine in in vivo artificial decidualization mouse model. In the last, LC3 and P62 were also observed in normal human proliferative, secretory, and decidua tissues. In conclusion, endometrial autophagy may be essential for embryo implantation, and it may be associated with endometrial decidualization during early pregnancy. KEY MESSAGE: • Autophagy-related markers were significantly decreased at implantation site. • Autophagy inhibition results in abnormal decidualization. • Autophagy is essential for embryo implantation.
胚胎着床是哺乳动物生殖过程中一个必不可少且复杂的过程。然而，很少有证据表明自噬在胚胎着床过程中发挥作用。为了确定自噬在妊娠小鼠着床期子宫中的可能作用，我们首先检测了自噬相关标志物 ATG5 和 LC3 在妊娠第 4、5 和 6 天（分别为 D4、D5 和 D6）的表达。与 D4 日相比，胚胎附着在接受性子宫内膜后的 D5 和 D6 日观察到自噬相关标志物表达下调。进一步的检查显示，与种植间隙部位相比，着床部位的自噬相关标志物 ATG5、ATG12、LC3、组织蛋白酶 B 和 P62 显著减少。透射电镜也观察到着床部位的自噬体数量减少。为了确认自噬在小鼠胚胎着床中的功能作用，我们用自噬抑制剂 3-甲基腺嘌呤和氯喹处理小鼠。用 3-甲基腺嘌呤处理后，蜕膜标志物 HOXA10 和孕激素受体的表达显著降低。此外，氯喹处理后，着床部位减少，HOXA10 和 PR 蛋白水平增加。此外，在体内人工蜕膜化小鼠模型中，用 3-甲基腺嘌呤和氯喹抑制自噬后，观察到子宫蜕膜化受损和 PR 和 HOXA10 蛋白水平失调。最后，还观察到正常人类增殖期、分泌期和蜕膜组织中的 LC3 和 P62。总之，子宫内膜自噬可能对胚胎着床至关重要，并且可能与早孕时的子宫内膜蜕膜化有关。
着床部位自噬相关标志物显著减少。
自噬抑制导致蜕膜化异常。
自噬对胚胎着床至关重要。
