Iron is an essential component of life. However, iron is also a potent biological toxin. Thus the bioavailability of iron must be stringently regulated. At the cellular level, if there is too little iron, a cell will lack the ability to meet its metabolic and biosynthetic requirements. If there is too much iron the cell become vulnerable to oxidative stress. Iron requiring metabolic reactions are found in both nuclei and cytoplasm and molecules in both compartments are vulnerable to oxidative stress. Indeed, iron-binding sites have been reported on DNA and iron induced DNA damage is well established. In the cytoplasm, ferritin regulates iron bioavailability. Recently, we and two other groups have provided evidence that ferritin is present in the nuclei of some cells. By virtue of its ability to take up and release iron, ferritin may be uniquely suited to both deliver iron to the nucleus as well as provide protection from iron induced oxidative stress. Our preliminary data show that nuclear ferritin is found in many cell types, not just in corneal epithelium and cell lines in culture as reported in the literature. In addition we provide evidence that nuclear ferritin is inducible in specific cell nuclei. The objective of this proposal is to characterize and elucidate the contribution of ferritin to nuclear functions and genomic stability. We propose to achieve this objective by use four specific aims to test four hypotheses: (i) test the hypothesis that cell stress results in recruitment of cytoplasmic ferritin to the nucleus, (ii) test the hypothesis that ferritin cytoplasm to nucleus translocation of ferritin is regulated and that H-rich ferritin is preferred to L-rich ferritin for translocations, (iii) test the hypothesis that ferritin binds DNA and determine if there is a preferred DNA sequence and ferritin subunit for binding (iv) test the hypothesis that ferritin protects DNA from iron-induced oxidative damage. At the conclusion of these studies, we expect to: 1) demonstrate that the translocation of ferritin to the nucleus is a dynamic process. 2) identify conditions that influence the translocation of ferritin to the nucleus 3) identify the mechanism by which ferritin is translocated to the nucleus and the preferred composition of nuclear ferritin, 4) determined if there is a preferred DNA sequence for ferritin binding and 5) identify mechanisms by which ferritin contributes to genomic stability. This work will lead to novel insights into the role of ferritin in cell biology and may have unparalled significance in the context of accessibility of metals to DNA. Because iron overload is associated with many forms of cancer, the outcome of the proposed studies could form the basis of therapeutic strategies for iron mediated diseases and may be useful in the development of an improved antitumor chemotherapy.
|Effective start/end date||8/15/01 → 7/31/02|
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