Rosario Fredrick J, Urschitz Johann, Razavy Haide, Elston Marlee, Theresa Powell L, Jansson Thomas
Obstetrics and Gynecology, University of Colorado, Aurora, Colorado, United States, 80045.
Institute for Biogenesis Research,, University of Hawaii Cancer Consortium, Hawaii, Hawaii, United States.
Clin Sci (Lond). 2025 Jun 18. doi: 10.1042/CS20243293.
Abnormal fetal growth is associated with perinatal complications and adult disease. The placental mechanistic target of rapamycin (mTOR) signaling activity is positively correlated to placental nutrient transport and fetal growth. However, if this association represents a mechanistic link, it remains unknown. We hypothesized that trophoblast-specific Mtor knockdown in late pregnant mice decreases trophoblast nutrient transport and inhibits fetal growth. PiggyBac Transposase-Enhanced Pronuclear Injection was performed to generate transgenic mice containing a trophoblast-specific Cyp19I.1 promoter-driven, doxycycline-inducible luciferase reporter transgene with a Mtor shRNAmir sequence in its 3' untranslated region (UTR). We induced Mtor knockdown by administration of doxycycline starting at E14.5. Dams were euthanized at E 17.5, and trophoblast-specific gene targeting was confirmed. Placental mTOR protein expression was reduced in these animals, which was associated with a marked inhibition of mTORC1 and mTORC2 signaling activity. Moreover, we observed a decreased expression of System A amino acid transporter isoform SNAT2 and the System L amino acid transporter isoform LAT1 in isolated trophoblast plasma membranes and lower fetal, placental weight and fetal: placental weight ratio. We also silence the MTOR in cultured primary human trophoblast cells, which inhibited the mTORC1 and C2 signaling, System A and System L amino acid transport activity, and markedly decreased the trafficking of LAT1 and SNAT2 to the plasma membrane. Inhibition of trophoblast mTOR signaling in late pregnancy is mechanistically linked to decreased placental nutrient transport and reduced fetal growth. Modulating trophoblast mTOR signaling may represent a novel intervention in pregnancies with abnormal fetal growth.
胎儿生长异常与围产期并发症及成人疾病相关。胎盘雷帕霉素机制性靶标（mTOR）信号活性与胎盘营养物质转运及胎儿生长呈正相关。然而，这种关联是否代表一种机制性联系尚不清楚。我们假设，在妊娠晚期小鼠中，滋养层特异性敲低Mtor会降低滋养层营养物质转运并抑制胎儿生长。采用猪尾巴转座酶增强原核注射法制备转基因小鼠，该小鼠含有由滋养层特异性Cyp19I.1启动子驱动的、强力霉素诱导型荧光素酶报告基因转基因，其3'非翻译区（UTR）含有Mtor shRNAmir序列。从胚胎第14.5天开始给予强力霉素以诱导Mtor敲低。在胚胎第17.5天对母鼠实施安乐死，并确认滋养层特异性基因靶向。这些动物的胎盘mTOR蛋白表达降低，这与mTORC1和mTORC2信号活性受到显著抑制有关。此外，我们观察到在分离的滋养层质膜中，A系统氨基酸转运体亚型SNAT2和L系统氨基酸转运体亚型LAT1的表达降低，同时胎儿、胎盘重量及胎儿:胎盘重量比也降低。我们还在培养的原代人滋养层细胞中沉默MTOR，这抑制了mTORC1和C2信号、A系统和L系统氨基酸转运活性，并显著减少了LAT1和SNAT2向质膜的转运。妊娠晚期抑制滋养层mTOR信号在机制上与胎盘营养物质转运减少及胎儿生长受限有关。调节滋养层mTOR信号可能代表对胎儿生长异常妊娠的一种新干预措施。
