MicroRNA‐301b reduces PPARγ expression in transgenic sickle mice and in hemin‐treated human pulmonary artery endothelial cells (1089.22)

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Sickle cell disease (SCD) is characterized by chronic intravascular hemolysis resulting in the release of hemin into the blood. Our preliminary microarray data indicate that PPARγ expression is significantly reduced in hemin‐treated human pulmonary artery endothelial cells (HPAECs). To examine post‐transcriptional mechanisms of PPARγ regulation in pulmonary hypertension in SCD (SCD‐PH), Townes knockin SCD mice aged 12‐weeks were gavaged daily with vehicle or rosiglitazone (RSG, 10 mg/kg/day) for 10 d. PPARγ was decreased and ET‐1 expression was increased in sickle mice (SS) compared to littermate control mice (AA). Using an in vitro model that mimics acute extracellular hemin release, HPAECs were treated with DMSO or hemin (5 μM) for 72 h ± RSG (10 μM) for the final 24 h. Similarly, hemin reduced PPARγ and increased ET‐1 expression in HPAECs. MicroRNA (miR‐301b), which negatively regulates PPARγ, was increased in SCD mice and in hemin‐treated HPAECs. In contrast, PPARγ activation attenuates increases in miR‐301b levels in SS mice and in hemin‐induced HPAECs. These findings suggest that hemolysis in SCD increases miR‐301b to reduce PPARγ and increase ET‐1 levels. These results suggest novel pathways for SCD‐PH pathogenesis and therapy.Grant Funding Source: Supported by AHA‐SDG 13SDG14150004,CEB F16788‐00, Atlanta VA 1I01BX001910, NIH HL074518, DK102167