| First Author | Arao Y | Year | 2013 |
| Journal | J Biol Chem | Volume | 288 |
| Issue | 29 | Pages | 21105-16 |
| PubMed ID | 23733188 | Mgi Jnum | J:201788 |
| Mgi Id | MGI:5515700 | Doi | 10.1074/jbc.M113.463455 |
| Citation | Arao Y, et al. (2013) Estrogen receptor alpha L543A,L544A mutation changes antagonists to agonists, correlating with the ligand binding domain dimerization associated with DNA binding activity. J Biol Chem 288(29):21105-16 |
| abstractText | A ligand-dependent nuclear transcription factor, ERalpha has two transactivating functional domains (AF), AF-1 and AF-2. AF-1 is localized in the N-terminal region, and AF-2 is distributed in the C-terminal ligand-binding domain (LBD) of the ERalpha protein. Helix 12 (H12) in the LBD is a component of the AF-2, and the configuration of H12 is ligand-inducible to an active or inactive form. We demonstrated previously that the ERalpha mutant (AF2ER) possessing L543A,L544A mutations in H12 disrupts AF-2 function and reverses antagonists such as fulvestrant/ICI182780 (ICI) or 4-hydoxytamoxifen (OHT) into agonists in the AF2ER knock-in mouse. Our previous in vitro studies suggested that the mode of AF2ER activation is similar to the partial agonist activity of OHT for WT-ERalpha. However, it is still unclear how antagonists activate ERalpha. To understand the molecular mechanism of antagonist reversal activity, we analyzed the correlation between the ICI-dependent estrogen-responsive element-mediated transcription activity of AF2ER and AF2ER-LBD dimerization activity. We report here that ICI-dependent AF2ER activation correlated with the activity of AF2ER-LBD homodimerization. Prevention of dimerization impaired the ICI-dependent ERE binding and transcription activity of AF2ER. The dislocation of H12 caused ICI-dependent LBD homodimerization involving the F-domain, the adjoining region of H12. Furthermore, F-domain truncation also strongly depressed the dimerization of WT-ERalpha-LBD with antagonists but not with E2. AF2ER activation levels with ICI, OHT, and raloxifene were parallel with the degree of AF2ER-LBD homodimerization, supporting a mechanism that antagonist-dependent LBD homodimerization involving the F-domain results in antagonist reversal activity of H12-mutated ERalpha. |
