Abstract
Objectives: Expression of placental oestrogen-related receptor gamma (ESRRG) is reduced by hypoxia, and reduced ESRRG signaling may contribute to hypoxia-induced placental dysfunction observed in fetal growth restriction (FGR). The regulatory relationship between hypoxia, hypoxia-inducible factor 1-alpha (HIF1A), and ESRRG is not fully understood. We investigated whether hypoxia-mediated activation of HIF-1alpha regulates ESRRG signaling, and whether an ESRRG agonist, DY131, can rescue abnormal cell turnover induced by hypoxia.
Methods: Placental explants (n=7) from uncomplicated pregnancies were treated with DY131 (20μM, 50μM) and cultured for 4 days under 1% or 21% O2. qPCR, western blotting, and immunochemistry were used to assess mRNA and protein levels of HIF-1alpha, ESRRG, and ESRRG’s downstream genes, HSD17B1, HSD11B2, CYP191.1 and PLAC1. hCG and LDH release were assessed by ELISA, as measures of syncytiotrophoblast differentiation and necrosis, respectively. Immunohistochemical staining of Ki67 and M30 was used to measure the number of cells in cycle and apoptotic cells.
Results: HIF-1alpha immunostaining was rarely observed in explants cultured in 21%O2 but was present in cytotrophoblast and stromal cells in explants exposed to hypoxic conditions. Hypoxia decreased the protein expression of ESRRG and the mRNA expression of ESRRG’s downstream genes. The number of cells in cycle was also decreased, while LDH release and the number of apoptotic cells were increased. DY131 treatment restored the hypoxia-mediated reduction in ESRRG protein expression, and HSD11B2 and CYP191.1 mRNA expression, and rescued adverse effects of hypoxia on cell turnover (cells in cycle, apoptosis, and LDH release).
Conclusion: The hypoxia-induced reduction in ESRRG signaling is via HIF1-alpha. The ESRRG agonist DY131 rescued the abnormal cell turnover in hypoxic placental explants. Modulating the ESRRG signaling pathway may offer a novel therapeutic option for the treatment of FGR.
Methods: Placental explants (n=7) from uncomplicated pregnancies were treated with DY131 (20μM, 50μM) and cultured for 4 days under 1% or 21% O2. qPCR, western blotting, and immunochemistry were used to assess mRNA and protein levels of HIF-1alpha, ESRRG, and ESRRG’s downstream genes, HSD17B1, HSD11B2, CYP191.1 and PLAC1. hCG and LDH release were assessed by ELISA, as measures of syncytiotrophoblast differentiation and necrosis, respectively. Immunohistochemical staining of Ki67 and M30 was used to measure the number of cells in cycle and apoptotic cells.
Results: HIF-1alpha immunostaining was rarely observed in explants cultured in 21%O2 but was present in cytotrophoblast and stromal cells in explants exposed to hypoxic conditions. Hypoxia decreased the protein expression of ESRRG and the mRNA expression of ESRRG’s downstream genes. The number of cells in cycle was also decreased, while LDH release and the number of apoptotic cells were increased. DY131 treatment restored the hypoxia-mediated reduction in ESRRG protein expression, and HSD11B2 and CYP191.1 mRNA expression, and rescued adverse effects of hypoxia on cell turnover (cells in cycle, apoptosis, and LDH release).
Conclusion: The hypoxia-induced reduction in ESRRG signaling is via HIF1-alpha. The ESRRG agonist DY131 rescued the abnormal cell turnover in hypoxic placental explants. Modulating the ESRRG signaling pathway may offer a novel therapeutic option for the treatment of FGR.
| Original language | English |
|---|---|
| Article number | NI.24. |
| Pages (from-to) | 13-14 |
| Number of pages | 2 |
| Journal | Placenta |
| Volume | 122 |
| DOIs | |
| Publication status | Published - 30 May 2022 |