The steroid hormone receptors are characterized by binding to relatively rigid, inflexible endogenous steroid ligands. Other members of the nuclear receptor superfamily bind to conformationally flexible lipids and show a corresponding degree of elasticity in the ligand-binding pocket. Here, we report the X-ray crystal structure of the oestrogen receptor a (ERa) bound to an oestradiol derivative with a prosthetic group, ortho-trifluoromethlyphenylvinyl, which binds in a novel extended pocket in the ligand-binding domain. Unlike ER antagonists with bulky side groups, this derivative is enclosed in the ligand-binding pocket, and acts as a potent agonist. This work shows that steroid hormone receptors can interact with a wider array of pharmacophores than previously thought through structural plasticity in the ligand-binding pocket.

The estrogen receptor (ER) subtypes, ERα and ERβ, modulate numerous signaling cascades in the brain to result in a variety of cell fates including neuronal differentiation. We report here that 17β-estradiol (E2) rapidly stimulates the autophosphorylation of α-Ca 2+ /calmodulin-dependent kinase II (αCaMKII) in immortalized NLT GnRH neurons, primary hippocampal neurons, and Cos7 cells cotransfected with ERα and αCaMKII. The E2-induced αCaMKII autophosphorylation is ERα-and Ca 2+ /calmodulin (CaM)-dependent. Interestingly, the hormone-dependent association of ERα with αCaMKII attenuates the positive effect of E2 on αCaMKII autophosphorylation, suggesting that ERα plays a complex role in modulating αCaMKII activity and may function to fine-tune αCaMKII-triggered signaling events. However, it appears as though the activating signal of E2 dominates the negative effect of ER since there is a clear, positive downstream response to E2-activated αCaMKII; pharmacological inhibitors and RNAi technology show that targets of ERα-mediated αCaMKII signaling include extracellular signal-regulated kinase 1/2 (ERK1/2), cAMP response elementbinding protein (CREB), and microtubule associated protein 2 (MAP2). These findings suggest a novel model for the modulation of αCaMKII signaling by ERα, which provides a molecular link as to how E2 might influence brain function.

No abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. (From -To) REPORT DATE (DD-MM-YYYY) March 2006 REPORT TYPE Annual Summary DATES COVERED AUTHOR(S)Erin O'Neill, B.S. 5d. PROJECT NUMBER Geoffrey Greene5e. TASK NUMBER E-mail: eionson@uchicago.edu 5f. WORK UNIT NUMBER PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBERUniversity of Chicago Chicago, Illinois 60637 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) U.S. Army Medical Research and Materiel CommandFort Detrick, Maryland 21702-5012 SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited SUPPLEMENTARY NOTES ABSTRACTRecent evidence has made it clear that ER-mediated extranuclear signaling is involved in the growth and survival of ER-expressing cells and tissues, including the mammary gland. Specifically, we are interested in examining the ability of ER action to modulate MAPK signaling as well as other key signaling molecules, and our main goals with this research are to: 1) better define the mechanism responsible for the observed cross-talk, 2) investigate the observed signaling in an animal model, 3) determine and compare the target genes that are regulated by ER rapid signaling versus classical ER transactivation, and 4) examine the subsequent cellular and biological responses to rapid 17β-estradiol (E2) action. Previously, we confirmed that E2 and other ER-specific ligands can rapidly phosphorylate and activate Erk-1 and -2 in the breast cancer cell line, MCF-7, an effect that is blocked by the potent ER antagonist, ICI 182, 780. We have also provided preliminary evidence that demonstrated that E2 administration to ovariectomized immature rats can induce Erk-1 and -2 phosphorylation in the uterine horn. We show here our continued investigation of ER-mediated Erk-1 and -2 activation in vivo, and that E2 administration can, in fact, result in a significant increase of Erk-1 and -2 phosphorylation over saline control in both the uterine horn and brain. In each case, E2-induced Erk-1 and -2 activation is at least partially decreased by the co-administration of ral...