Reduced systemic glucose facilitates exocytosis of epinephrine from adrenal gland. The PHD2-HIF2α-EPO axis induces erythrocytosis and hypoglycemia. HIF2α and not HIF1α modulates PNMT during epinephrine synthesis in chromaffin cells. Our findings are also highly relevant to the testing of small molecule PHD inhibitors in phase III clinical trials for patients with renal anemia. Based on these results, we propose that the PHD2-HIF2α axis in the adrenal medulla regulates the synthesis of epinephrine, whereas in REPCs, it indirectly induces the release of this hormone. Simultaneous loss of PHD2 in renal erythropoietin (EPO)-producing cells (REPCs) stimulated HIF2α-driven EPO overproduction, excessive RBC formation (erythrocytosis), and systemic hypoglycemia, which is necessary and sufficient to enhance exocytosis of epinephrine from the adrenal medulla. Here, we reveal that deficiency of HIF (hypoxia inducible factors) prolyl hydroxylase domain protein-2 (PHD2) in the adrenal medulla of mice results in HIF2α-mediated reduction in phenylethanolamine N-methyltransferase (PNMT) expression, and consequent reduction in epinephrine synthesis. ![]() ![]() The adrenal gland and its hormones regulate numerous fundamental biological processes however, the impact of hypoxia signaling on adrenal function remains poorly understood.
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