Basak Trishita, Dey Amit Kumar, Banerjee Rachana, Paul Sandip, Maiti Tushar Kanti, Ain Rupasri
Division of Cell Biology and Physiology, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
Regional Centre for Biotechnology, Faridabad, India.
Stem Cells. 2021 Feb;39(2):210-226. doi: 10.1002/stem.3305. Epub 2020 Dec 4.
Enrichment of angiomotin (AMOT) in the ectoplacental cone of E7.5 murine placenta prompted our investigation on the role of AMOT in trophoblast differentiation. We show here that AMOT levels increased in mouse placenta during gestation and also upon induction of differentiation in trophoblast stem cell ex vivo. Proteomic data unravelling AMOT-interactome in trophoblast cells indicated a majority of AMOT interactors to be involved in protein translation. In-depth analysis of AMOT-interactome led to identification of eukaryotic translation initiation factor 4A (eIF4A) as the most plausible AMOT interactor. Loss of function of AMOT enhanced, whereas, gain in function resulted in decline of global protein synthesis in trophoblast cells. Bioinformatics analysis evaluating the potential energy of AMOT-eIF4A binding suggested a strong AMOT-eIF4A interaction using a distinct groove encompassing amino acid residue positions 238 to 255 of AMOT. Co-immunoprecipitation of AMOT with eIF4A reaffirmed AMOT-eIF4A association in trophoblast cells. Deletion of 238 to 255 amino acids of AMOT resulted in abrogation of AMOT-eIF4A interaction. In addition, 238 to 255 amino acid deletion of AMOT was ineffective in eliciting AMOT's function in reducing global protein synthesis. Interestingly, AMOT-dependent sequestration of eIF4A dampened its loading to the m -GTP cap and hindered its interaction with eIF4G. Furthermore, enhanced AMOT expression in placenta was associated with intrauterine growth restriction in both rats and humans. These results not only highlight a hitherto unknown novel function of AMOT in trophoblast cells but also have broad biological implications as AMOT might be an inbuilt switch to check protein synthesis in developmentally indispensable trophoblast cells.
血管动蛋白（AMOT）在E7.5小鼠胎盘的外胎盘锥中的富集促使我们研究AMOT在滋养层细胞分化中的作用。我们在此表明，在妊娠期间以及体外诱导滋养层干细胞分化时，小鼠胎盘中的AMOT水平会升高。蛋白质组学数据揭示了滋养层细胞中AMOT相互作用组，表明大多数AMOT相互作用蛋白都参与蛋白质翻译。对AMOT相互作用组的深入分析导致鉴定出真核翻译起始因子4A（eIF4A）是最有可能的AMOT相互作用蛋白。AMOT功能丧失会增强，而功能获得则导致滋养层细胞中整体蛋白质合成下降。评估AMOT-eIF4A结合势能的生物信息学分析表明，使用包含AMOT氨基酸残基位置238至255的独特凹槽，AMOT与eIF4A有强烈相互作用。AMOT与eIF4A的共免疫沉淀再次证实了滋养层细胞中AMOT-eIF4A的关联。删除AMOT的238至255个氨基酸会导致AMOT-eIF4A相互作用的消除。此外，AMOT的238至255个氨基酸缺失在引发AMOT降低整体蛋白质合成的功能方面无效。有趣的是，AMOT对eIF4A的依赖性隔离会抑制其加载到m -GTP帽上，并阻碍其与eIF4G的相互作用。此外，胎盘AMOT表达增强与大鼠和人类的宫内生长受限有关。这些结果不仅突出了AMOT在滋养层细胞中迄今未知的新功能，而且还具有广泛的生物学意义，因为AMOT可能是一个内在开关，用于检查发育中不可或缺的滋养层细胞中的蛋白质合成。
