ERRγ1 and Aromatase Expression in Human Placental Tissues from Term Deliveries of Large for Gestational Age Newborns

Abstract

Introduction: Being born either large (LGA) or small for gestational age (SGA) has been associated with an increased risk of developing metabolic syndrome in adulthood. However, the mechanism underlying this early programming remained unclear. Estrogen-related receptor gamma (ERRγ) is an orphan nuclear receptor with a high expression in human placenta, particularly ERRγ1. ERRγ has been proposed to play a central role in controlling genes involved in energy metabolism. In placenta, ERRγ1 acts as an oxygen-responsive transcription factor regulating aromatase (Aro) expression during trophoblast differentiation. Aromatase is an enzyme that catalyzes the synthesis of estrogens from androgens and is located in the syncytiotrophoblast. An adequate estrogen-androgen balance is required for normal pregnancy progression. Our aim was to analyze ERRγ1 and Aro mRNA in human placenta from term LGA newborns. We propose that ERRγ1 and CYP19A1 expressions in human placenta from LGA newborns are impaired, which would modify fetal programming of LGA newborns, since an imbalance in intrauterine estrogen-androgen ratio would be occurred Methods: Total RNA was obtained from placental tissues of LGA (GA: 39-41 weeks, n=8) and adequate for gestational age (AGA; 39-40 weeks, n=10) newborns. ERRγ1 and Aro mRNA variants were analyzed by RT2-PCR. Primers for Aro analysis were specific for Total aromatase (TotalAro) binding in exons 2-3 and for Active aromatase (ActAro) in exons 9-10. Aro protein was analyzed by Western-blot. Results: ERRγ1 mRNA was significantly higher in LGA compare to AGA. TotalAro mRNA was significantly lower in LGA in comparison with AGA control. Similar results with Aro protein. In contrast ActAro/TotalAro ratio was higher in LGA compared to the AGA control. Conclusions: High expression of ERRγ1 as well as ActAro/TotalAro ratio in LGA suggests that ERRγ1 is involved in ActAro variant expression and hence disrupted estrogen-androgen balance in the intrauterine environment. We propose that dysregulation of ERRγ1 in placenta might modify the estrogen-androgen balance in the intrauterine environment in LGA newborns, possibly representing one of the key factors in the regulation of fetal programming.