Effects of gamma irradiation on the DNA-protein complex between the estrogen response element and the estrogen receptor

Abstract : Signaling by estrogens, risk factors in breast cancer, is mediated through their binding to the estrogen receptor protein (ER), followed by the formation of a complex between ER and a DNA sequence, called estrogen response element (ERE). Anti-estrogens act as competitive inhibitors by blocking the signal transduction. We have studied in vitro the radiosensitivity of the complex between ER alpha, a subtype of this receptor, and a DNA fragment bearing ERE, as well as the influence of an estrogen (estradiol) or an anti-estrogen (tamoxifen) on this radiosensitivity. We observe that the complex is destabilized upon irradiation with gamma rays in aerated aqueous solution. The analysis of the decrease of binding abilities of the two partners shows that destabilization is mainly due to the damage to the protein. The destabilization is reduced when irradiating in presence of tamoxifen and is increased in presence of estradiol. These effects are due to opposite influences of the ligands on the loss of binding ability of ER. The mechanism that can account for our results is: binding of estradiol or tamoxifen induces distinct structural changes of the ER ligand-binding domain that can trigger (by allostery) distinct structural changes of the ER DNA-binding domains and thus, can differently affect ER-ERE interaction.
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Submitted on : Monday, October 25, 2010 - 4:22:48 PM
Last modification on : Friday, April 26, 2019 - 10:48:02 AM

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Viktorie Stisova, Stéphane Goffinont, Mélanie Spotheim-Maurizot, Marie Davidkova. Effects of gamma irradiation on the DNA-protein complex between the estrogen response element and the estrogen receptor. Radiation Physics and Chemistry, Elsevier, 2010, 79 (8), pp.880-889. ⟨10.1016/j.radphyschem.2010.03.009⟩. ⟨hal-00529465⟩

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