Kong Xiangfeng, Wang Xiaoqiu, Yin Yulong, Li Xilong, Gao Haijun, Bazer Fuller W, Wu Guoyao
Department of Animal Science, Texas A&M University, College Station, Texas Hunan Provincial Engineering Research Center of Healthy Livestock and Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.
Department of Animal Science, Texas A&M University, College Station, Texas.
Biol Reprod. 2014 Nov;91(5):106. doi: 10.1095/biolreprod.113.113977. Epub 2014 Sep 24.
Insufficient placental growth is a major factor contributing to intrauterine growth retardation in mammals. There is growing evidence that putrescine produced from arginine (Arg) and proline via ornithine decarboxylase is a key regulator of angiogenesis, embryogenesis, as well as placental and fetal growth. However, the underlying mechanisms are largely unknown. The present study tested the hypothesis that putrescine stimulates protein synthesis by activating the mechanistic target of rapamycin (mTOR) signaling pathway in porcine trophectoderm cell line 2 cells. The cells were cultured for 2 to 4 days in customized Arg-free Dulbecco modified Eagle Ham medium containing 0, 10, 25, or 50 μM putrescine or 100 μM Arg. Cell proliferation, protein synthesis, and degradation, as well as the abundance of total and phosphorylated mTOR, ribosomal protein S6 kinase 1, and eukaryotic initiation factor 4E-binding protein-1 (4EBP1), were determined. Our results indicate that putrescine promotes cell proliferation and protein synthesis in a dose- and time-dependent manner, which was inhibited by difluoro-methylornithine (an inhibitor of ornithine decarboxylase). Moreover, supplementation of culture medium with putrescine increased the abundance of phosphorylated mTOR and its downstream targets, 4EBP1 and p70 S6K1 proteins. Collectively, these findings reveal a novel and important role for putrescine in regulating the mTOR signaling pathway in porcine placental cells. We suggest that dietary supplementation with or intravenous administration of putrescine may provide a new and effective strategy to improve survival and growth of embryos/fetuses in mammals.
胎盘生长不足是导致哺乳动物宫内生长受限的主要因素。越来越多的证据表明，由精氨酸（Arg）和脯氨酸通过鸟氨酸脱羧酶产生的腐胺是血管生成、胚胎发育以及胎盘和胎儿生长的关键调节因子。然而，其潜在机制在很大程度上尚不清楚。本研究检验了以下假设：腐胺通过激活猪滋养外胚层细胞系2细胞中的雷帕霉素作用靶点（mTOR）信号通路来刺激蛋白质合成。将细胞在定制的不含Arg的杜氏改良 Eagle Ham培养基中培养2至4天，该培养基含有0、10、25或50 μM腐胺或100 μM Arg。测定细胞增殖、蛋白质合成与降解，以及总mTOR和磷酸化mTOR、核糖体蛋白S6激酶1和真核起始因子4E结合蛋白1（4EBP1）的丰度。我们的结果表明，腐胺以剂量和时间依赖性方式促进细胞增殖和蛋白质合成，这被二氟甲基鸟氨酸（鸟氨酸脱羧酶抑制剂）所抑制。此外，在培养基中添加腐胺会增加磷酸化mTOR及其下游靶点4EBP1和p70 S6K1蛋白的丰度。总体而言，这些发现揭示了腐胺在调节猪胎盘细胞mTOR信号通路中的新的重要作用。我们建议，通过饮食补充或静脉注射腐胺可能为提高哺乳动物胚胎/胎儿的存活率和生长提供一种新的有效策略。
