College of Veterinary Medicine, Jilin University, Changchun, P. R. China.
Reproductive Medical Center, the Second Hospital of Jilin University, Changchun, P. R. China.
Biol Reprod. 2023 Sep 12;109(3):299-308. doi: 10.1093/biolre/ioad066.
Melatonin is important for oocyte maturation, fertilization, early embryonic development, and embryo implantation, but less knowledge is available regarding its role in decidualization. The present study found that melatonin did not alter the proliferation of human endometrial stromal cells (ESCs), as well as cell cycle progress, but suppressed stromal differentiation after binding to the melatonin receptor 1B (MTNR1B), which was visualized in decidualizing ESCs. Further analysis evidenced that application of melatonin resulted in the diminishment for NOTCH1 and RBPJ expression. Supplementation of recombinant NOTCH1 protein (rNOTCH1) counteracted the impairment of stromal differentiation conferred by melatonin, while the addition of the NOTCH signaling pathway inhibitor DAPT aggravated the differentiation progress. Meanwhile, melatonin might restrain the expression and transcriptional activity of nuclear factor erythroid 2-related factor 2 (NRF2), whose blockage accelerated the fault of stromal differentiation under the context of melatonin, but this restraint was subsequently ameliorated by rNOTCH1. Forkhead box O 1 (FOXO1) was identified as a downstream target of melatonin in decidualization. Repression of NRF2 antagonized the retrieval of rNOTCH1 due to aberrant FOXO1 expression elicited by melatonin. Moreover, melatonin brought about the occurrence of oxidative stress accompanied by an obvious accumulation of intracellular reactive oxygen species and a significant reduction in glutathione (GSH) content, as well as enzymatic activities of glutathione peroxidase and glutathione reductase, whereas supplementation of rNOTCH1 improved the above-mentioned effects. Nevertheless, this improvement was disrupted by the blockage of NRF2 and FOXO1. Furthermore, addition of GSH rescued the defect of stromal differentiation by melatonin. Collectively, melatonin might impair endometrial decidualization by restraining the differentiation of ESCs dependent on NOTCH1-NRF2-FOXO1-GSH pathway after binding to the MTNR1B receptor.
褪黑素对卵母细胞成熟、受精、早期胚胎发育和胚胎着床很重要，但关于其在蜕膜化中的作用知之甚少。本研究发现，褪黑素不会改变人子宫内膜基质细胞（ESCs）的增殖，也不会改变细胞周期进程，但会抑制与褪黑素受体 1B（MTNR1B）结合后的基质分化，这在蜕膜化的 ESCs 中可以观察到。进一步的分析表明，褪黑素的应用导致 NOTCH1 和 RBPJ 表达减少。补充重组 NOTCH1 蛋白（rNOTCH1）可以逆转褪黑素引起的基质分化损伤，而 NOTCH 信号通路抑制剂 DAPT 的添加则加剧了分化进程。同时，褪黑素可能会抑制核因子红细胞 2 相关因子 2（NRF2）的表达和转录活性，NRF2 的阻断在褪黑素作用下加速了基质分化的缺陷，但随后被 rNOTCH1 改善。叉头框 O1（FOXO1）被鉴定为褪黑素在蜕膜化中的下游靶标。NRF2 的抑制拮抗了由于褪黑素引起的异常 FOXO1 表达导致 rNOTCH1 的恢复。此外，褪黑素引起氧化应激的发生，伴随着细胞内活性氧的明显积累和谷胱甘肽（GSH）含量的显著减少，以及谷胱甘肽过氧化物酶和谷胱甘肽还原酶的酶活性降低，而 rNOTCH1 的补充改善了上述效应。然而，NRF2 和 FOXO1 的阻断破坏了这种改善。此外，GSH 的补充挽救了褪黑素引起的基质分化缺陷。总之，褪黑素可能通过与 MTNR1B 受体结合后抑制依赖于 NOTCH1-NRF2-FOXO1-GSH 途径的 ESCs 分化，从而损害子宫内膜蜕膜化。
