HIF‐1 alpha Mediates Sex‐specific miR‐30a Expression in Neonatal Hyperoxic Lung Injury: Implications for Bronchopulmonary Dysplasia

Abstract

BackgroundBronchopulmonary Dysplasia (BPD) is characterized by an arrest in lung development with severe impairment of alveolar septation and vascular development. Premature male neonates are at a greater risk of developing bronchopulmonary dysplasia (BPD). The reasons underlying sexually dimorphic outcomes in premature neonates are not known. Neonatal female mice have improved alveolarization and pulmonary vascular development compared to male littermates in a murine model of BPD. Analysis of the pulmonary transcriptome suggests that miR‐30a, may modulate these sex‐specific differences in gene expression. HIF‐1α plays an important role in post‐natal lung development, especially in recovery from hyperoxic injury and acute lung injury. We hypothesized that differential sex‐specific expression of miR‐30a is mediated through HIF‐1α.MethodsMale and female neonatal WT (C57BL6) mice were exposed to hyperoxia (P1–P5; saccular stage of lung development) and euthanized on P7 or P21 after recovery in normoxia. Human pulmonary microvascular endothelial cells (HPMECs; from 18–24 weeks gestation donors; 3 male and 3 female) were obtained from ScienCell (Carlsbad, California). They were cultured in endothelial cell media per protocol. Cells from passage from 3 to 6 were used for experiments. For hyperoxic exposure, cells were incubated in 95% O2 and 5% CO2 at 37 °C for upto 72 hours. Cells in normoxia were maintained in air and 5% CO2. miR‐30a and Dll4 (miR‐30a target) expression was measured. Hif‐1α binding to its targets genes (by ChIP‐qPCR) and expression was measured in vivo. To further establish potential regulation of miR‐30a by Hif‐1α, miR‐30a expression after Hif‐1α inhibition was measured in neonatal HPMECs.ResultsExpression of miR‐30a was increased and Dll4 decreased on PND21 in hyperoxia‐exposed neonatal female mice compared to males. On PND21, hyperoxia‐ exposed female mice showed a significant increase in Hif‐1α binding to target genes compared to room air controls and hyperoxia‐exposed male mice. In contrast to male mice, females did not show a decrease in Hif‐1α expression at PND21 after early hyperoxia exposure and this was accompanied by a significant decrease in Phd2 expression in female mice, which metabolizes Hif‐1α. Motif analysis revealed a hypoxia response element (HRE) [AG]CGTG site 428 base pairs upstream of miR‐30a. siRNA mediated loss of Hif‐1α expression in human pulmonary microvascular endothelial cells decreased miR‐30a and increased Dll4 mRNA and protein expression.ConclusionsHif‐1α mediated differential sex‐specific miR‐30a expression may contribute to protection from hyperoxic lung injury in female neonatal mice and contribute to the sex‐specific differences seen in BPD.Support or Funding InformationK08 HL‐127103R03 HL‐141572This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.