Estrogen receptor α L429 and A430 regulate 17β-estradiol-induced cell proliferation via CREB1

17 beta-Estradiol (E2)-dependent cell proliferation requires both estrogen receptor alpha (ER alpha)-based integrated control of gene transcription and kinase pathways activation. Such coordination of intracellular E2:ER alpha-dependent signaling mechanisms is finely tuned by receptor association with specific partner proteins. Recently, we identified the leucine (L) 429 and alanine (A) 430 within the ER alpha ligand binding domain as important residues for receptor non-covalent interaction to ubiquitinated species [i.e., ER alpha ubiquitin-binding surface (ER alpha UBS)1 and for E2-induced ER alpha activation. To date, if these two ER alpha amino acids are involved in the control of E2-dependent pathways required for cell proliferation is unknown. Here, by using stably expressing ER alpha mutated in L429 and A430 (i.e., L429A,A430G LAAG) cell lines, we show that L429 and A430 are critical for E2-induced cell proliferation, PI3K/AKT pathway activation, and ER alpha-mediated transcriptional changes. Moreover, we demonstrate that these two receptor structural determinants direct the E2-induced PI3K/AKT/CREB1 pathway activation and CREB1-mediated transcriptional activity that in turn control the hormone-induced cell proliferation. As a whole, our data demonstrate for the first time that the ER alpha UBS contributes to the modulation of E2-induced ER alpha-mediated cell proliferation and provide a novel connection between the receptor structure and the functional molecular mechanisms by which E2:ER alpha complex can regulate cell processes. (C) 2015 Elsevier Inc All rights reserved.