Date of Award
Master of Science
Iron homeostasis is essential in preventing iron toxicity and deficiency. Several nutrients have been shown to have interactions with iron, specifically vitamin A.A few recently discovered proteins play crucial roles in maintaining iron homeostasis. One central group of governing proteins is known as the iron regulatory proteins (IRPs). Understanding how IRPs respond to altered cellular concentrations of other nutrients may be vital for the treatment or prevention of iron toxicity and deficiency. These studies were conducted to determine if IRPs play a role the perturbation of iron homeostasis in vitamin A deficiency and supplementation. In human hepatoma (HepG2) cells we found that IRP-RNA binding activity was induced when cells were treated with an iron chelator and slightly repressed when administered retinoic acid (RA). Hence, we used a rat model to determine the role of IRPs in iron deficiency, vitamin A deficiency and a combination of these deficiencies. Acute iron deficiency in rats significantly induced hepatic IRP-RNA binding activity and reduced hepatic ferritin to undetectable amounts. Furthermore, we found RA supplementation inhibited the increase in IRP-RNA binding activity to a level not significantly different from the control. This inhibition of IRP-RNA binding activity by RA supplementation was correlated with a 34% reduction in transferrin receptor (TfR) abundance and a partial restoration of hepatic ferritin abundance. Our additional studies utilizing HepG2 cells provided evidence that RA mediates ferritin in a dose-dependant manner. These findings suggest that IRPs play a role in vitamin A mediated alterations of iron homeostasis; providing insight into prevention and treatment of iron deficiency and rationale for cautioning retinoid users of the potential for hepatic iron accumulation.
Stacy Eileen Schroeder
Schroeder, Stacy Eileen, "Vitamin A modulation of iron homeostasis : the role of iron regulatory proteins" (2006). Retrospective Theses and Dissertations. 19096.