Biology subjects

Novick, S.

Publications and source records attributed to Novick, S..

3 recordsLinked to original sources

bioRxiv2025

A ternary switch determines ERα LBD conformation

The transcription factor estrogen receptor (ER) is the primary driver of ER+ breast cancer progression and a target of multiple FDA-approved anticancer drugs. Ligand-dependent activity of ER is determined by the conformation of helix-12 (H12) within the ligand binding domain (LBD), but how H12 transitions from an unliganded (apo) state to active (estrogen-bound) or inactive (SERM/SERD-bound) states remains unresolved. Here, we present the first crystal structure of an apo ER LBD, revealing a third distinct H12 conformation that regulates receptor activity. Structural mass-spectrometry, small-angle X-ray scattering, functional analysis and molecular dynamics simulations reveal that the apo conformation of H12 is stable in the absence of ligand, but is destabilised by Y537S and D538G breast cancer mutations driving constitutive activation. We propose a model in which H12 functions as a ternary molecular switch to determine receptor activity. These findings provide critical insights into the ligand-dependent and -independent regulation of ER and have significant implications for therapeutic intervention.

biochemistry↗

bioRxiv2020

Dual-Mechanism Estrogen Receptor Inhibitors Reveal an Ensemble of Binding Modes for Robust Breast Cancer Antagonism

Efforts to improve estrogen receptor-a (ER)-targeted therapies in breast cancer have relied upon a single mechanism, with ligands having a single side chain on the ligand core that extends outward to determine antagonism of breast cancer growth. Here, we describe inhibitors with two ER-targeting moieties, one of which uses an alternate structural mechanism to generate full antagonism, freeing the side chain to independently determine other critical properties of the ligands. By combining two molecular targeting approaches into a single ER ligand, we have generated antiestrogens that function through new mechanisms and structural paradigms to achieve antagonism. These dual-mechanism ER inhibitors (DMERIs) cause alternate, non-canonical structural perturbations of the receptor ligand-binding domain (LBD) to drive antagonism of proliferation in ER-positive breast cancer cells and in allele-specific resistance models. Solution structural and coregulator peptide binding analyses with DMERIs highlight marked differences from current standard-of-care, single-mechanism antiestrogens. These findings uncover an enhanced flexibility of the ER LBD through which it can access non-consensus conformational modes in response to DMERI binding, broadly and effectively suppressing ER activity. Significance StatementTo address the unmet clinical need for effectively suppressing estrogen receptor (ER) activity with both de novo resistance and in advanced ER-positive breast cancers that are resistant to standard-of-care antiestrogens, we have developed dual-mechanism ER inhibitors (DMERIs) that employ two distinct ER targeting moieties. These DMERI elicited non-canonical structural perturbations of the receptor ligand-binding domain and stabilized multiple antagonist sub-states within the dimer to generate highly efficacious antagonism of proliferation in ER-positive breast cancer cells and in allele-specific resistance models. This work reveals new conformational modes by which the activity of ER can be effectively suppressed to block breast cancer proliferation.

cancer biology↗

bioRxiv2019

HDX-MS reveals structural determinants for RORγ hyperactivation by synthetic agonists

Members of the nuclear receptor (NR) superfamily regulate both physiological and pathophysiological processes ranging from development and metabolism1 to inflammation2 and cancer3. As ligand-gated transcription factors, synthetic small molecules targeting NRs are often deployed as therapeutics to correct aberrant NR signaling or as chemical probes to explore the role of the receptor in physiology4. However, nearly half of NRs do not have specific cognate ligands or its unclear if they possess ligand dependent activities and these receptors are called orphans. Here we demonstrate that ligand-dependent action of the orphan nuclear receptor ROR{gamma} can be defined by selectively disrupting putative endogenous--but not synthetic--ligand binding. Furthermore, the characterization of a library of ROR{gamma} modulators reveals that structural dynamics of the receptor assessed by HDX-MS correlate with activity in biochemical and cell-based assays. These findings are corroborated with X-ray co-crystallography and site-directed mutagenesis to collectively reveal the structural determinants of ROR{gamma} ligand-dependent activation, critical for designing full agonists for application in cancer immunotherapy. Combined these observations support a model of receptor activation to more accurately describe ROR{gamma} pharmacology. Likewise, this bump-and-hole inspired approach could be extended to other orphan NRs to explore the ligand-dependent activities that are important for defining pharmacology.

biophysics↗