Sequestration of eIF4A by Angiomotin: a novel mechanism to restrict global protein synthesis in trophoblast cells

alkiviadis.1961 shared this article with you from Inoreader Sequestration of eIF4A by Angiomotin: a novel mechanism to restrict global protein synthesis in trophoblast cells Via STEM CELLS Schematic representation of AMOT function during differentiation of TSCs. AMOT is expressed by ectoplacental cone on E7.5 during mouse development. EPC harbors TSC niche. Low levels of AMOT in TSCs ensure optimum protein synthesis. Differentiation dependent up regulation of AMOT lead to sequestration of eIF4A and subsequent decrease of eIF4A‐eIF4G interaction and decreased eIF4F complex formation at the m7‐GTP cap resulting in decreased protein synthesis. Abstract 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 238‐255 of AMOT. Co‐immunoprecipitation of AMOT with eIF4A re‐affirmed AMOT‐eIF4A association in trophoblast cells. Deletion of 238‐255 amino acids of AMOT resulted in abrogation of AMOT‐eIF4A interaction. In addition, 238‐255 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 m7‐GTP cap and hindered its interaction with eIF4G. Furthermore, enhanced AMOT expression in placenta was associated with intra‐uterine 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. © AlphaMed Press 2020 Significance Statement Trophoblast cells, the parenchymal cells of placenta, execute most placental functions, indispensible for successful pregnancy. They arise from the trophoblast stem cell (TSC) niche during development. TSCs are recognized as the developmental counterpart of ES cells in the context of placental development. Inadequate, trophoblast differentiation leads to adverse pregnancy outcome, which is a global health concern. Expanding the knowledge on the regulatory circuits of trophoblast development is therefore essential to improve the success of pregnancy. View on the web Inoreader. Take back control of your news feed. Follow us on Twitter and Facebook.