MicroRNA: Molecular Micromanagers of Iron Metabolism and Oxygen Sensing
Abstract
Iron deficiency (ID) is estimated to affect one-third of the world's population. As an essential micronutrient, iron is required for DNA synthesis, cellular proliferation, and oxygen transport. Iron is potentially toxic through its ability to promote the generation of ROS, thus cellular iron is tightly controlled. Although a family of cytosolic RNA binding proteins plays a central role in maintaining cellular iron homeostasis, evidence suggests that iron levels may be coordinated by microRNA (miRNA). miRNA are noncoding RNA that recognize and bind to partially complementary sites of target mRNA and regulate gene expression via translational repression and mRNA degradation. With the previous identification of ~10 differentially expressed miRNA in ID rat livers, we chose to study two of the identified miRNA, miR-181d and miR-210. The central hypothesis was miRNA regulated by dietary iron deficiency play a role in the modulation of target mRNA, and function as key elements in regulating iron homeostasis. Using the bioinformatics programs miRWalk and TargetScan, we identified mitoferrin 1 and isocitrate dehydrogenase 1 were conserved predicted targets of miR-181d and cytoglobin was a conserved predicted target of miR-210. Next, reporter assays confirmed the direct interaction of the miRNA and their respective mRNA targets. Finally, in vitro experiments were conducted to demonstrate iron chelation and miRNA overexpression influenced mRNA abundance and translational repression of target mRNA. Our results confirm that miR-181d contributes to the regulation of isocitrate dehydrogenase 1. Additionally, although miR-210 was significantly upregulated in response to ID in rat livers and in vitro iron chelation, cytoglobin expression was upregulated in both conditions. Therefore, the results demonstrate dietary iron deficiency and chelation upregulate (1) miR-181d expression that influences isocitrate dehydrogenase 1 gene expression and translation and (2) cytoglobin gene expression and translation.
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- OSU Dissertations [11222]