Iron is an essential element for virtually all-living organisms. It is required as a cofactor for a multitude of proteins of diverse biological function. Iron plays a central role in the formation of hemoglobin and myoglobin and in many vital biochemical pathways and enzyme systems including energy metabolism, neurotransmitter production, collagen formation and immune system function. As a transition metal, iron also has useful ligand-binding and redox properties. At the same time, iron poses enormous problems because of the easy inter-conversion of Fe(II) and Fe(III), the very property that makes it attractive for biological redox processes (1). The reduced iron, Fe(II) can produce highly reactive hydroxyl and lipid radicals, which can damage lipid membranes, nucleic acids and proteins. In the million years of evolution, nature has not developed a pathway for excretion of iron in humans, so the body concentration of iron can only be regulated by absorption to match losses of iron.Under normal circumstances 1-2 mg of iron enters and leaves the body each day. In the body, iron is distributed in three pools -functional, storage and transport iron. The absorbed iron circulates in the plasma bound to transferrin (Tf) (transport iron) and the excess iron gets stored in the parenchymal cells of the liver and reticuloendothelial macrophages as ferritin (storage iron). About 0.1% of total body iron is circulating bound to Tf. Nearly 80% of iron is utilized for hemoglobin synthesis in the bone marrow. Approximately 10-15% is present in muscle fibers (myoglobin) and in other tissues as enzymes and cytochromes (functional iron).Homeostatic mechanisms regulating the absorption, transport, storage and mobilization of cellular iron are therefore of critical importance in iron metabolism, and a rich biology and chemistry underlie all of these mechanisms. The last decade has seen a rapid advancement of knowledge in iron metabolism. Modern techniques in molecular biology and biochemistry are giving new insights through the identification and characterization of proteins involved in iron homeostasis. This review focuses on the current developments in the understanding of iron homeostasis and the delicate mechanisms involved in the regulation of iron in the body.
AbstractAlthough iron is a relatively abundant element in the universe, it is estimated that more than 2 billion people worldwide suffer from iron deficiency anemia. Iron deficiency results in impaired production of ironcontaining proteins, the most prominent of which is hemoglobin. Cellular iron deficiency inhibits cell growth and subsequently leads to cell death. Hemochromatosis, an inherited disorder results in disproportionate absorption of iron and the extra iron builds up in tissues resulting in organ damage. As both iron deficiency and iron overload have adverse effects, cellular and systemic iron homeostasis is critically important. Recent advances in the field of iron metabolism have led to newer understanding of the pathways involved in iron homeostasis and the ...