L-proline (proline) is a key regulator of embryogenesis, placental development, and fetal growth. However, the underlying mechanisms that support the beneficial effects of proline are largely unknown. This study used porcine trophectoderm cell line 2 (pTr2) to investigate the underlying mechanisms of proline in cell proliferation and redox homeostasis. Cells were cultured in the presence of 0, 0.25, 0.50, or 1.0 mmol/L proline for an indicated time. The results showed that 0.5 and 1.0 mmol/L proline enhanced cell viability. These effects of proline (0.5 mmol/L) were accompanied by the enhanced protein abundance of p-mTORC1, p-p70S6K, p-S6, and p-4E-BP1. Additionally, proline dose-dependently enhanced the mRNA expression of proline transporters [solute carrier family (SLC) 6A20, SLC36A1, SLC36A2, SLC38A1, and SLC38A2], elevated proline concentration, and protein abundance of proline dehydrogenase (PRODH). Furthermore, proline addition (0.25 or 0.5 mmol/L) resulted in lower abundance of p-AMPKα when compared with a control. Of note, proline resulted in lower reactive oxygen species (ROS) level, upregulated mRNA expression of the catalytic subunit of glutamate–cysteine ligase (GCLC) and glutathione synthetase (GSS), as well as enhanced total (T)-GSH and GSH concentration when compared with a control. These data indicated that proline activates themTORC1 signaling and modulates the intracellular redox environment via enhancing proline transport.

中文翻译：

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L-脯氨酸激活雷帕霉素复合物 1 的哺乳动物靶标并调节猪滋养外胚层细胞的氧化还原环境

L-脯氨酸（脯氨酸）是胚胎发生、胎盘发育和胎儿生长的关键调节剂。然而，支持脯氨酸有益作用的潜在机制在很大程度上是未知的。本研究使用猪滋养外胚层细胞系 2 (pTr2) 来研究脯氨酸在细胞增殖和氧化还原稳态中的潜在机制。细胞在 0、0.25、0.50 或 1.0 mmol/L 脯氨酸存在下培养指定时间。结果表明，0.5 和 1.0 mmol/L 脯氨酸提高了细胞活力。脯氨酸 (0.5 mmol/L) 的这些作用伴随着 p-mTORC1、p-p70S6K、p-S6 和 p-4E-BP1 蛋白质丰度的增加。此外，脯氨酸剂量依赖性地增强脯氨酸转运蛋白 [溶质载体家族 ( SLC ) 6A20的 mRNA 表达，SLC36A1、SLC36A2、SLC38A1和SLC38A2 ]、脯氨酸浓度升高和脯氨酸脱氢酶 (PRODH) 的蛋白质丰度。此外，与对照相比，添加脯氨酸（0.25 或 0.5 mmol/L）导致 p-AMPK α丰度较低。值得注意的是，脯氨酸导致活性氧 (ROS) 水平降低，谷氨酸 - 半胱氨酸连接酶 ( GCLC ) 和谷胱甘肽合成酶 ( GSS )催化亚基的 mRNA 表达上调，以及总 (T)-GSH 和 GSH 浓度增加与对照相比。这些数据表明脯氨酸激活它们的TORC1信号并通过增强脯氨酸转运调节细胞内氧化还原环境。