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Here, we demonstrate that a single biochemical assay is able to predict the tissue-selective pharmacology of an array of selective estrogen receptor modulators (SERMs). We describe an approach to classify estrogen receptor (ER) modulators based on dynamics of the receptor-ligand complex as probed with hydrogen/deuterium exchange (HDX) mass spectrometry. Differential HDX mapping coupled with cluster and discriminate analysis effectively predicted tissue-selective function in most, but not all, cases tested. We demonstrate that analysis of dynamics of the receptor-ligand complex facilitates binning of ER modulators into distinct groups based on structural dynamics. Importantly, we were able to differentiate small structural changes within ER ligands of the same chemotype. In addition, HDX revealed differentially stabilized regions within the ligand-binding pocket that may contribute to the different pharmacology phenotypes of the compounds independent of helix 12 positioning. In summary, HDX provides a sensitive and rapid approach to classify modulators of the estrogen receptor that correlates with their pharmacological profile. discriminate analysis ͉ hydrogen/deuterium exchange ͉ mass spectrometry T he estrogen receptors (ER␣ and ER␤) are important transcriptional regulators that mediate a number of fundamental processes including regulation of the reproductive system and the maintenance of skeletal and cardiovascular tone. As such, these receptors are the molecular targets of drugs used to treat diseases such as breast cancer and osteoporosis. Both beneficial and detrimental effects of ER ligands have been demonstrated in target tissues, thus tissue-selective ER ligands have been developed and are termed selective estrogen receptor modulators (SERMs). Traditional drug discovery programs for ER modulators most often involve the use of a receptor-binding assay as a primary screen to identify high-affinity ligands, followed by the use of in vitro cellbased assays to determine the functional activity of a given ligand (1). Compounds with the desired intrinsic properties for affinity and selective functional response are then evaluated for in vivo efficacy in animal models of the targeted disease. Although this drugdiscovery paradigm has been used successfully to identify most of the clinically-relevant SERMs discovered to date, the ability of in vitro biochemical and cell-based functional assays to translate to in vivo tissue selectivity has been limited. Cofactor recruitment assays have proven to be a useful tool to detect ligand-induced conformational changes for many nuclear receptors but can be less effective for profiling SERMs because the key coactivator interaction surface (AF-2) has been blocked by the ligand-induced repositioning of helix 12.Classical approaches for structural analysis of receptor-ligand interaction involve the use of x-ray crystallography or NMR spectroscopy. The importance of studying changes to protein dynamics during ER modulation has been demonstrated by Tamrazi et al. (2). In a serie...

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Familial expansile osteolysis is a rare bone dysplasia which is transmitted as an autosomal dominant trait in a large kindred in Northern Ireland. The gene which causes the disease shows tight linkage with several polymorphic markers on chromosome 18q with a maximum lod score of 11.53 at a recombination fraction of 0.00 with D18S64. The gene is flanked by D18S35 and D18S61 and is located at chromosome 18q21.1-q22. Mapping a new locus for a gene involved in regulation of bone metabolism may also have implications in the study of Paget's disease of bone which is a common related bone dysplasia.

Benzopyran selective estrogen receptor beta agonist-1 (SERBA-1) shows potent, selective binding and agonist function in estrogen receptor beta (ERbeta) in vitro assays. X-ray crystal structures of SERBA-1 in ERalpha and beta help explain observed beta-selectivity of this ligand. SERBA-1 in vivo demonstrates involution of the ventral prostate in CD-1 mice (ERbeta effect), while having no effect on gonadal hormone levels (ERalpha effect) at 10x the efficacious dose, consistent with in vitro properties of this molecule.