Nonerythroid alphaII spectrin is required for recruitment of FANCA and XPF to nuclear foci induced by DNA interstrand cross-links.
The events responsible for repair of DNA interstrand cross-links in mammalian cells, the proteins involved and their interactions with each other are poorly understood. The present study demonstrates that the structural protein nonerythroid alpha spectrin (alphaSpIISigma*), present in normal human cell nuclei, plays an important role in repair of DNA ... interstrand cross-links. These results show that alphaSpIISigma* relocalizes to nuclear foci after damage of normal human cells with the DNA interstrand cross-linking agent 8-methoxypsoralen plus ultraviolet A (UVA) light and that FANCA and the known DNA repair protein XPF localize to the same nuclear foci. That alphaSpIISigma* is essential for this re-localization is demonstrated by the finding that in cells from patients with Fanconi anemia complementation group A (FA-A), which have decreased ability to repair DNA interstrand cross-links and decreased levels of alphaSpIISigma*, there is a significant reduction in formation of damage-induced XPF as well as alphaSpIISigma* nuclear foci, even though levels of XPF are normal in these cells. In corrected FA-A cells, in which levels of alphaSpIISigma* are restored to normal, numbers of damage-induced nuclear foci are also returned to normal. Co-immunoprecipitation studies show that alphaSpIISigma*, FANCA and XPF co-immunoprecipitate with each other from normal human nuclear proteins. These results demonstrate that alphaSpIISigma*, FANCA and XPF interact with each other in the nucleus and indicate that there is a close functional relationship between these proteins. These studies suggest that an important role for alphaSpIISigma* in the nucleus is to act as a scaffold, aiding in recruitment and alignment of repair proteins at sites of damage.
Mesh Terms:
Blotting, Western, Cell Line, Cell Nucleus, Cross-Linking Reagents, DNA Adducts, DNA Damage, DNA Repair, DNA-Binding Proteins, Dose-Response Relationship, Radiation, Fanconi Anemia Complementation Group A Protein, Fluorescent Antibody Technique, Indirect, Humans, Methoxsalen, Nuclear Proteins, Precipitin Tests, Proteins, Spectrin, Time Factors, Ultraviolet Rays
Blotting, Western, Cell Line, Cell Nucleus, Cross-Linking Reagents, DNA Adducts, DNA Damage, DNA Repair, DNA-Binding Proteins, Dose-Response Relationship, Radiation, Fanconi Anemia Complementation Group A Protein, Fluorescent Antibody Technique, Indirect, Humans, Methoxsalen, Nuclear Proteins, Precipitin Tests, Proteins, Spectrin, Time Factors, Ultraviolet Rays
J. Cell. Sci.
Date: Mar. 01, 2003
PubMed ID: 12571280
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