26 research outputs found
Activation of Crtc2/Creb1 in skeletal muscle enhances weight loss during intermittent fasting
The Creb-Regulated Transcriptional Coactivator (Crtc) family of transcriptional coregulators drive Creb1-mediated transcription effects on metabolism in many tissues, but the in vivo effects of Crtc2/Creb1 transcription on skeletal muscle metabolism are not known. Skeletal muscle-specific overexpression of Crtc2 (Crtc2 mice) induced greater mitochondrial activity, metabolic flux capacity for both carbohydrates and fats, improved glucose tolerance and insulin sensitivity, and increased oxidative capacity, supported by upregulation of key metabolic genes. Crtc2 overexpression led to greater weight loss during alternate day fasting (ADF), selective loss of fat rather than lean mass, maintenance of higher energy expenditure during the fast and reduced binge-eating during the feeding period. ADF downregulated most of the mitochondrial electron transport genes, and other regulators of mitochondrial function, that were substantially reversed by Crtc2-driven transcription. Glucocorticoids acted with AMPK to drive atrophy and mitophagy, which was reversed by Crtc2/Creb1 signaling. Crtc2/Creb1-mediated signaling coordinates metabolic adaptations in skeletal muscle that explain how Crtc2/Creb1 regulates metabolism and weight loss
The SARS-CoV-2 spike protein binds and modulates estrogen receptors
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein binds angiotensin-converting enzyme 2 as its primary infection mechanism. Interactions between S and endogenous proteins occur after infection but are not well understood. We profiled binding of S against >9000 human proteins and found an interaction between S and human estrogen receptor alpha (ER alpha). Using bioinformatics, supercomputing, and experimental assays, we identified a highly conserved and functional nuclear receptor coregulator (NRC) LXD-like motif on the S2 sub-unit. In cultured cells, S DNA transfection increased ER alpha cytoplasmic accumulation, and S treatment induced ER-dependent biological effects. Non-invasive imaging in SARS-CoV-2-infected hamsters localized lung pathology with increased ER alpha lung levels. Postmortem lung experiments from infected hamsters and humans confirmed an increase in cytoplasmic ER alpha and its colocalization with S in alveolar macrophages. These findings describe the discovery of a S-ER alpha interaction, imply a role for S as an NRC, and advance knowledge of SARS-CoV-2 biology and coronavirus disease 2019 pathology
Exploring the Structural Compliancy versus Specificity of the Estrogen Receptor Using Isomeric Three-Dimensional Ligands
The
estrogen receptors (ERs) bind with high affinity to many structurally
diverse ligands by significantly distorting the contours of their
ligand-binding pockets. This raises a question: To what degree is
ER able to distinguish between structurally related regioisomers and
enantiomers? We have explored the structural compliance and specificity
of ERα with a set of ligands having a 7-oxa-bicyclo[2.2.1]Âhept-5-ene
sulfonate core and basic side chains typical of selective ER modulators
(SERMs). These ligands have two regioisomers, each of which is a racemate
of enantiomers. Using orthogonal protecting groups and chiral HPLC,
we isolated all 4 isomers and assigned their absolute stereochemistry
by X-ray analysis. The 1S,2R,4S isomer has a 80â170-fold higher
affinity for ERα than the others, and it profiles as a partial
agonist/antagonist in cellular reporter gene assays and in suppressing
proliferation of MCF-7 breast cancer cells with subnanomolar potency,
far exceeding that of the other isomers. It is the only isomer found
bound to ERα by X-ray analysis after crystallization with four-isomer
mixtures of closely related analogs. Thus, despite the general compliance
of this receptor for binding a large variety of ligand structures,
ER demonstrates marked structural specificity and stereospecificity
by selecting a single component from a mixture of structurally related
isomers to drive ER-regulated cellular activity. Our findings lay
the necessary groundwork for seeking unique ER-mediated pharmacological
profiles by rational structural perturbations of two different types
of side chains in this unprecedented class of ER ligands, which may
prove useful in developing more effective endocrine therapies for
breast cancer
Systems Structural Biology Analysis of Ligand Effects on ERα Predicts Cellular Response to Environmental Estrogens and Anti-hormone Therapies
Environmental estrogens and anti-hormone therapies for breast cancer have diverse tissue- and signaling-pathway-selective outcomes, but how estrogen receptor alpha (ERα) mediates this phenotypic diversity is poorly understood. We implemented a statistical approach to allow unbiased, parallel analyses of multiple crystal structures, and identified subtle perturbations of ERα structure by different synthetic and environmental estrogens. Many of these perturbations were in the sub-Ă
range, within the noise of the individual structures, but contributed significantly to the activities of synthetic and environmental estrogens. Combining structural perturbation data from many structures with quantitative cellular activity profiles of the ligands enabled identification of structural rules for ligand-specific allosteric signalingâpredicting activity from structure. This approach provides a framework for understanding the diverse effects of environmental estrogens and for guiding iterative medicinal chemistry efforts to generate improved breast cancer therapies, an approach that can be applied to understanding other ligand-regulated allosteric signaling pathways
Predictive features of ligandâspecific signaling through the estrogen receptor
Some estrogen receptorâα (ERα)âtargeted breast cancer therapies such as tamoxifen have tissueâselective or cellâspecific activities, while others have similar activities in different cell types. To identify biophysical determinants of cellâspecific signaling and breast cancer cell proliferation, we synthesized 241 ERα ligands based on 19 chemical scaffolds, and compared ligand response using quantitative bioassays for canonical ERα activities and Xâray crystallography. Ligands that regulate the dynamics and stability of the coactivatorâbinding site in the Câterminal ligandâbinding domain, called activation functionâ2 (AFâ2), showed similar activity profiles in different cell types. Such ligands induced breast cancer cell proliferation in a manner that was predicted by the canonical recruitment of the coactivators NCOA1/2/3 and induction of the GREB1 proliferative gene. For some ligand series, a single interâatomic distance in the ligandâbinding domain predicted their proliferative effects. In contrast, the Nâterminal coactivatorâbinding site, activation functionâ1 (AFâ1), determined cellâspecific signaling induced by ligands that used alternate mechanisms to control cell proliferation. Thus, incorporating systems structural analyses with quantitative chemical biology reveals how ligands can achieve distinct allosteric signaling outcomes through ERα