Iron regulation of endothelial hemoglobin alpha - || project summary iron is a critical micronutrient for hemoprotein maturation and redox signaling

Iron deficiency anemia (IDA) is associated with heart failure, chronic kidney disease, and chronic inflammation. In all these disease states, intravenous iron delivery is often used to replenish iron stores and improve patient outcomes. The use of intravenous iron, however, can have harmful consequences causing patients to undergo periods of iron overload and iron deficiency during treatment. Furthermore, each of these diseases is mediated in part by endothelial dysfunction. Thus, deciphering the molecular mechanisms of iron homeostasis in the endothelium provides a previously undefined framework for potential translation to important cardiovascular diseases. The regulation of blood flow, a primary function of the endothelium, is reliant upon many hemoproteins, especially hemoglobin alpha (HBA) in the microvasculature. In homeostatic conditions, HBA is expressed uniquely in the resistance arteries and regulates the scavenging and production of nitric oxide. Hemoglobin is tightly regulated by systemic iron homeostasis in erythrocytes, but IT is not known how iron regulates HBA in endothelial cells. Our preliminary data suggest iron is an important regulator of endothelial HBA. The central hypothesis of the proposed studies is that the regulation of endothelial function by systemic iron homeostasis is dependent upon intracellular iron and heme availability which work in conjunction to regulate HBA. In order to test this hypothesis, we will use mouse models of iron overload and iron deficiency anemia. We will use endothelial specific knockout of transferrin receptor 1 (an iron import protein) and FLVCR1A (a heme export protein) to modulate endothelial iron and heme concentrations independent of systemic iron homeostasis. Changes in blood flow and no signaling will be assessed with laser speckle contrast imaging. To investigate the link between iron import and HBA expression, we will utilize a peptide developed by our lab which increases blood flow by disrupting the HBA/enos complex. Biochemical assays will be used to assess endothelial heme concentrations and HBA maturation. The long-term goal of this project is to provide novel insights into the mechanisms by which iron regulates endothelial function and allow US to better understand the vascular etiologies of chronic diseases.