Maternal erythrocyte ENT1–mediated AMPK activation counteracts placental hypoxia and supports fetal growth
Seisuke Sayama, Anren Song, Benjamin C. Brown, Jacob Couturier, Xiaoli Cai, Ping Xu, Changhan Chen, Yangxi Zheng, Takayuki Iriyama, Baha Sibai, Monica Longo, Rodney E. Kellems, Angelo D’Alessandro, Yang Xia
Seisuke Sayama, Anren Song, Benjamin C. Brown, Jacob Couturier, Xiaoli Cai, Ping Xu, Changhan Chen, Yangxi Zheng, Takayuki Iriyama, Baha Sibai, Monica Longo, Rodney E. Kellems, Angelo D’Alessandro, Yang Xia
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Research Article Development Hematology

Maternal erythrocyte ENT1–mediated AMPK activation counteracts placental hypoxia and supports fetal growth

Abstract

Insufficient O2 supply is frequently associated with fetal growth restriction (FGR), a leading cause of perinatal mortality and morbidity. Although the erythrocyte is the most abundant and only cell type to deliver O2 in our body, its function and regulatory mechanism in FGR remain unknown. Here, we report that genetic ablation of mouse erythrocyte equilibrative nucleoside transporter 1 (eENT1) in dams, but not placentas or fetuses, results in FGR. Unbiased high-throughput metabolic profiling coupled with in vitro and in vivo flux analyses with isotopically labeled tracers led us to discover that maternal eENT1–dependent adenosine uptake is critical in activating AMPK by controlling the AMP/ATP ratio and its downstream target, bisphosphoglycerate mutase (BPGM); in turn, BPGM mediates 2,3-BPG production, which enhances O2 delivery to maintain placental oxygenation. Mechanistically and functionally, we revealed that genetic ablation of maternal eENT1 increases placental HIF-1α; preferentially reduces placental large neutral aa transporter 1 (LAT1) expression, activity, and aa supply; and induces FGR. Translationally, we revealed that elevated HIF-1α directly reduces LAT1 gene expression in cultured human trophoblasts. We demonstrate the importance and molecular insight of maternal eENT1 in fetal growth and open up potentially new diagnostic and therapeutic possibilities for FGR.

Authors

Seisuke Sayama, Anren Song, Benjamin C. Brown, Jacob Couturier, Xiaoli Cai, Ping Xu, Changhan Chen, Yangxi Zheng, Takayuki Iriyama, Baha Sibai, Monica Longo, Rodney E. Kellems, Angelo D’Alessandro, Yang Xia

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Figure 4

Metabolomic screening result from EPO and E1FE erythrocytes and 13C-labeled adenosine flux experiment with erythrocyte enzyme activity.

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Metabolomic screening result from EPO and E1FE erythrocytes and 13C-labe...
(A) Description of metabolomic screening of the erythrocytes. (B) Metabolomics detected the changes of purine related metabolites in erythrocytes isolated from pregnant mice (n = 3). (C) AMP/ATP ratio was calculated from the metabolomic screening result (n = 3). (D) Description of 13C-labeled adenosine flux experiment. Result from flux experiment comparing erythrocytes from WT and ENT1-KO mice. AMP derived from the uptake of adenosine in the supernatant was reduced in erythrocytes from ENT1-KO mice (n = 3). (E–H) p-AMPK levels, BPGM activity, 2,3-BPG, and p50 levels were all decreased in erythrocytes from E1FE dams compared with control (n = 5-8). (I and J) Decreased GSH/GSSG ratio and accumulation of ROS in erythrocytes from E1FE dams compared with control. Values represent the mean ± SEM. *P < 0.05, ***P < 0.005 (n = 4–5). Two-tailed Student’s t test was used for statistical analysis.