内质网应激对牛胚胎发育能力和抗冷冻能力的作用。
Role of endoplasmic reticulum stress on developmental competency and cryo-tolerance in bovine embryos.
机构信息
Faculty of Agriculture, Saga University, Saga, Japan; Faculty of Animal Husbandry, Bangladesh Agricultural University, Mymensingh, Bangladesh; The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.
Faculty of Agriculture, Saga University, Saga, Japan.
出版信息
Theriogenology. 2020 Jan 15;142:131-137. doi: 10.1016/j.theriogenology.2019.09.042. Epub 2019 Sep 28.
Endoplasmic reticulum (ER) stress, a dysfunction in protein folding capacity of the ER, is involved in many physiological responses including mammalian reproductive systems. Studies have shown that ER stress interferes with the developmental process of in vitro oocyte maturation and embryo development; however, little is known about its effects on bovine preimplantation embryonic development. In this study, we examined the effects of ER stress during IVC on developmental competency and cryo-tolerance in bovine embryos. IVF-derived zygotes were cultured in CR1aa medium supplemented with tauroursodeoxycholic acid (TUDCA) and/or tunicamycin (TM), which are ER stress-inhibitory and stress-inducing agents, respectively, for 8 days. TM treatment decreased the blastocyst developmental rate and increased the percentage of apoptotic cells compared to that in the control group (10.2 ± 2.3% vs. 39.75 ± 1.3% and 17.8 ± 1.2% vs. 3.6 ± 1.1%, respectively; P < 0.01). However, the blastocyst developmental rate was increased and the percentage of apoptotic cells was decreased by addition of TUDCA in IVC medium compared to that in the control group (50.9 ± 0.9% vs. 39.75 ± 1.3% and 1.13 ± 1.0% vs. 3.6 ± 1.1%, respectively; P < 0.01). Importantly, in the group treated with TM plus TUDCA, the developmental rate and the percentage of apoptotic cells in blastocysts were similar to that in the control group, indicating that TUDCA ameliorates the adverse effects of TM alone on embryo development. In addition, TUDCA treatment significantly reduced the reactive oxygen species, expression of ER stress (GRP78, ATF4, ATF6, IER1, and sXBP1) and pro-apoptotic (CHOP and BAX) genes, while it increased anti-apoptotic BCL2 gene expression and glutathione levels. Moreover, TUDCA improved blastocyst cryo-tolerance as marked by a significantly increased hatching rate and decreased the number of apoptotic cells recorded at 48 h after a post-warming. Therefore, in concordance with a previous report in mice or pig, we showed that TUDCA supplementation during IVC increases the developmental competency of bovine in vitro-derived embryos. Additionally, we found that the presence of TUDCA in IVC medium improves the cryo-tolerance of bovine embryos. These results suggest that modulation of ER stress during IVC contributes to the production of high-quality bovine embryos in terms of cryo-tolerance.
内质网（ER）应激是 ER 蛋白折叠能力障碍的一种，参与许多生理反应，包括哺乳动物生殖系统。研究表明，ER 应激会干扰体外卵母细胞成熟和胚胎发育的过程；然而，其对牛囊胚前胚胎发育的影响知之甚少。在这项研究中，我们研究了 ER 应激在 IVC 过程中对牛胚胎发育能力和抗冷冻能力的影响。体外受精获得的胚胎在添加牛磺熊脱氧胆酸（TUDCA）和/或衣霉素（TM）的 CR1aa 培养基中培养 8 天，TM 和 TUDCA 分别为 ER 应激抑制和诱导剂。与对照组相比，TM 处理降低了囊胚的发育率，增加了凋亡细胞的百分比（分别为 10.2 ± 2.3% vs. 39.75 ± 1.3%和 17.8 ± 1.2% vs. 3.6 ± 1.1%；P < 0.01）。然而，与对照组相比，在 IVC 培养基中添加 TUDCA 可增加囊胚的发育率并降低凋亡细胞的百分比（分别为 50.9 ± 0.9% vs. 39.75 ± 1.3%和 1.13 ± 1.0% vs. 3.6 ± 1.1%；P < 0.01）。重要的是，在 TM 加 TUDCA 处理组中，囊胚的发育率和凋亡细胞百分比与对照组相似，表明 TUDCA 改善了 TM 单独处理对胚胎发育的不良影响。此外，TUDCA 处理显著降低了活性氧、内质网应激（GRP78、ATF4、ATF6、IER1 和 sXBP1）和促凋亡（CHOP 和 BAX）基因的表达，同时增加了抗凋亡 BCL2 基因的表达和谷胱甘肽水平。此外，TUDCA 提高了囊胚的抗冷冻能力，表现为解冻后 48 小时孵化率显著提高，凋亡细胞数量减少。因此，与之前在小鼠或猪中的报道一致，我们表明 TUDCA 在 IVC 期间的补充增加了牛体外胚胎的发育能力。此外，我们发现 IVC 培养基中 TUDCA 的存在提高了牛胚胎的抗冷冻能力。这些结果表明，IVC 过程中 ER 应激的调节有助于提高牛胚胎的冷冻耐受性和胚胎质量。
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