School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia.
Cells. 2023 Nov 16;12(22):2640. doi: 10.3390/cells12222640.
The culture of embryos in the non-essential amino acid L-proline (Pro) or its analogues pipecolic acid (PA) and L-4-thiazolidine carboxylic acid (L4T) improves embryo development, increasing the percentage that develop to the blastocyst stage and hatch. Staining of 2-cell and 4-cell embryos with tetramethylrhodamine methyl ester and 2',7'-dichlorofluorescein diacetate showed that the culture of embryos in the presence of Pro, or either of these analogues, reduced mitochondrial activity and reactive oxygen species (ROS), respectively, indicating potential mechanisms by which embryo development is improved. Inhibition of the Pro metabolism enzyme, proline oxidase, by tetrahydro-2-furoic-acid prevented these reductions and concomitantly prevented the improved development. The ways in which Pro, PA and L4T reduce mitochondrial activity and ROS appear to differ, despite their structural similarity. Specifically, the results are consistent with Pro reducing ROS by reducing mitochondrial activity while PA and L4T may be acting as ROS scavengers. All three may work to reduce ROS by contributing to the GSH pool. Overall, our results indicate that reduction in mitochondrial activity and oxidative stress are potential mechanisms by which Pro and its analogues act to improve pre-implantation embryo development.
胚胎在非必需氨基酸 L-脯氨酸（Pro）或其类似物哌啶酸（PA）和 L-4-噻唑啉羧酸（L4T）中的培养改善了胚胎的发育，增加了发育到囊胚阶段和孵化的比例。用四甲基罗丹明甲酯和 2'，7'-二氯荧光素二乙酸酯对 2 细胞和 4 细胞胚胎进行染色，表明在 Pro 或这些类似物存在的情况下培养胚胎分别降低了线粒体活性和活性氧（ROS），这表明胚胎发育得到改善的潜在机制。四氢-2-呋喃酸抑制脯氨酸氧化酶（Pro 代谢酶）可防止这些减少，并同时防止发育得到改善。脯氨酸、PA 和 L4T 降低线粒体活性和 ROS 的方式似乎不同，尽管它们的结构相似。具体而言，这些结果与 Pro 通过降低线粒体活性来降低 ROS 的结果一致，而 PA 和 L4T 可能作为 ROS 清除剂发挥作用。这三者都可能通过为 GSH 池做出贡献来减少 ROS。总的来说，我们的结果表明，线粒体活性和氧化应激的降低是 Pro 及其类似物改善胚胎前体发育的潜在机制。
