Ligand-binding domains of nuclear receptors facilitate tight control of split CRISPR activity

Nuclear receptors function as ligand-regulated transcription factors and modulate the expression of sets of genes in response to varying concentrations of ligands. The ligand modulators can be endogenous metabolites that function as hormones, or they can be exogenous substances, such as pharmaceutical agents or environmental substances of natural or man-made origin, which in some cases can cause endocrine disruption. Ligands modulate nuclear receptor activity by binding to their ligand-binding domains and stabilizing conformations that lead either to transcriptional activation or repression. The ligand-binding pocket is somewhat flexible, and binding affinities can be measured over a 10-million-fold range (i.e., with equilibrium dissociation constant values ranging from ca. 0.01 nM to 100 μM). Thus, it is not surprising that by binding a large variety of structures, some nuclear receptors can appear to be promiscuous; however, when affinity is considered, the binding patterns are more restricted. The spectrum of ligands that bind to the estrogen receptor has been most thoroughly investigated. Those from natural sources include natural products in food, such as soy isoflavones and whole grain lignans, as well as microbial products and components from wood. Aside from pharmaceuticals, man-made estrogen ligands can be found in industrial products, such as alkyl phenols from nonionic detergents, bisphenols from plastics, indicator dye impurities, polymer chemicals, and chlorinated aromatics and pesticides. Exogenous ligands are also known for the androgen and progesterone receptors. While it is possible that endocrine disruption can result from exogenous chemicals acting directly as ligands for the nuclear receptors, endocrine disruption needs to be considered in the broader context; thus, compounds also need to be assessed for their effects at other levels, such as on endogenous hormone production, transport, metabolism, and clearance, and at points in signal transduction cascades that are beyond the ligand-receptor interaction.

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Paired opposing leukocyte receptors recognizing rapidly evolving ligands are subject to homogenization of their ligand binding domains

Immunogenetics ◽

10.1007/s00251-011-0553-5 ◽

2011 ◽

Vol 63 (12) ◽

pp. 809-820 ◽

Cited By ~ 7

Author(s):

Sigbjørn Fossum ◽

Per Christian Saether ◽

John Torgils Vaage ◽

Michael Rory Daws ◽

Erik Dissen

Keyword(s):

Ligand Binding ◽

Binding Domains ◽

Leukocyte Receptors

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Biochemical and NMR Mapping of the Interface between CREB-binding Protein and Ligand Binding Domains of Nuclear Receptor

Journal of Biological Chemistry ◽

10.1074/jbc.m411697200 ◽

2004 ◽

Vol 280 (7) ◽

pp. 5682-5692 ◽

Cited By ~ 12

Author(s):

Fabrice A. C. Klein ◽

R. Andrew Atkinson ◽

Noelle Potier ◽

Dino Moras ◽

Jean Cavarelli

Keyword(s):

Ligand Binding ◽

Nuclear Receptor ◽

Binding Protein ◽

Creb Binding Protein ◽

Binding Domains

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Expression of SMRTβ promotes ligand-induced activation of mutated and wild-type retinoid receptors

Blood ◽

10.1182/blood-2003-10-3583 ◽

2004 ◽

Vol 104 (13) ◽

pp. 4226-4235 ◽

Cited By ~ 7

Author(s):

Sylvie Côté ◽

Suzan McNamara ◽

Daria Brambilla ◽

Andrea Bianchini ◽

Giovanni Rizzo ◽

...

Keyword(s):

Ligand Binding ◽

Nuclear Receptors ◽

Transcriptional Activation ◽

Leukemic Cell ◽

Wild Type ◽

Specific Expression ◽

Retinoid Receptors ◽

Leukemic Cell Lines ◽

All Trans Retinoic Acid ◽

New Evidence

Abstract Nuclear receptors are ligand-modulated transcription factors regulated by interactions with corepressors and coactivators, whose functions are not fully understood. Acute promyelocytic leukemia (APL) is characterized by a translocation, t(15;17), that produces a PML/RARα fusion oncoprotein, whose abnormal transcriptional function is successfully targeted by pharmacologic levels of all-trans-retinoic acid (ATRA). Mutations in the ligand-binding domain of PML/RARα that confer resistance to ATRA have been studied by expression in nonhematopoietic cells, such as Cos-1. Here, we show that ATRA binding and transcriptional activation by the same PML/RARα mutant differ markedly between nonhematopoietic and leukemic cell lines. Differential expression of the corepressor isoform silencing mediator for retinoid and thyroid receptors β (SMRTβ) correlates with increased ligand binding and transcription by the mutant PML/RARα. Transient and stable overexpression of SMRTβ in hematopoietic cells that only express SMRTα increased ATRA binding, ligand-induced transcription, and ATRA-induced cell differentiation. This effect may not be limited to abnormal nuclear receptors, because overexpression of SMRTβ increased ATRA-induced binding and transcriptional activation of wild-type receptors PML/RARα and RARα. Our results suggest a novel role for the SMRTβ isoform whereby its cell-specific expression may influence the binding and transcriptional capacities of nuclear receptors, thus providing new evidence of distinct functions of corepressor isoforms and adding complexity to transcriptional regulation.

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Ligand modulates the conversion of DNA-bound vitamin D3 receptor (VDR) homodimers into VDR-retinoid X receptor heterodimers

Molecular and Cellular Biology ◽

10.1128/mcb.14.5.3329-3338.1994 ◽

1994 ◽

Vol 14 (5) ◽

pp. 3329-3338

Author(s):

B Cheskis ◽

L P Freedman

Keyword(s):

Ligand Binding ◽

Vitamin D3 ◽

Hormone Receptors ◽

Steroid Receptors ◽

Dependent Manner ◽

D3 Receptor ◽

Vitamin D3 Receptor ◽

Binding Domains

Protein dimerization facilitates cooperative, high-affinity interactions with DNA. Nuclear hormone receptors, for example, bind either as homodimers or as heterodimers with retinoid X receptors (RXR) to half-site repeats that are stabilized by protein-protein interactions mediated by residues within both the DNA- and ligand-binding domains. In vivo, ligand binding among the subfamily of steroid receptors unmasks the nuclear localization and DNA-binding domains from a complex with auxiliary factors such as the heat shock proteins. However, the role of ligand is less clear among nuclear receptors, since they are constitutively localized to the nucleus and are presumably associated with DNA in the absence of ligand. In this study, we have begun to explore the role of the ligand in vitamin D3 receptor (VDR) function by examining its effect on receptor homodimer and heterodimer formation. Our results demonstrate that VDR is a monomer in solution; VDR binding to a specific DNA element leads to the formation of a homodimeric complex through a monomeric intermediate. We find that 1,25-dihydroxyvitamin D3, the ligand for VDR, decreases the amount of the DNA-bound VDR homodimer complex. It does so by significantly decreasing the rate of conversion of DNA-bound monomer to homodimer and at the same time enhancing the dissociation of the dimeric complex. This effectively stabilizes the bound monomeric species, which in turn serves to favor the formation of a VDR-RXR heterodimer. The ligand for RXR, 9-cis retinoic acid, has the opposite effect of destabilizing the heterodimeric-DNA complex. These results may explain how a nuclear receptor can bind DNA constitutively but still act to regulate transcription in a fully hormone-dependent manner.

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A large-scale expression strategy for multimeric extracellular protein complexes using Drosophila S2 cells and its application to the recombinant expression of heterodimeric ligand-binding domains of taste receptor

Protein Science ◽

10.1002/pro.3271 ◽

2017 ◽

Vol 26 (11) ◽

pp. 2291-2301 ◽

Cited By ~ 3

Author(s):

Atsuko Yamashita ◽

Eriko Nango ◽

Yuji Ashikawa

Keyword(s):

Ligand Binding ◽

Large Scale ◽

Protein Complexes ◽

Recombinant Expression ◽

Taste Receptor ◽

Extracellular Protein ◽

S2 Cells ◽

Binding Domains ◽

Drosophila S2 Cells

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Rapid Estrogen-Induced Phosphorylation of the SRC-3 Coactivator Occurs in an Extranuclear Complex Containing Estrogen Receptor

Molecular and Cellular Biology ◽

10.1128/mcb.25.18.8273-8284.2005 ◽

2005 ◽

Vol 25 (18) ◽

pp. 8273-8284 ◽

Cited By ~ 54

Author(s):

Fuzhong F. Zheng ◽

Ray-Chang Wu ◽

Carolyn L. Smith ◽

Bert W. O'Malley

Keyword(s):

Estrogen Receptor ◽

Ligand Binding ◽

Direct Interaction ◽

Activation Function ◽

Estrogen Receptor Α ◽

Binding Domain ◽

Phosphorylation Sites ◽

Binding Domains ◽

Nongenomic Action ◽

Binding Groove

ABSTRACT SRC-3/AIB1/ACTR/pCIP/RAC3/TRAM1 is a primary transcriptional coregulator for estrogen receptor (ER). Six SRC-3 phosphorylation sites have been identified, and these can be induced by steroids, cytokines, and growth factors, involving multiple kinase signaling pathways. Using phosphospecific antibodies for six phosphorylation sites, we investigated the mechanisms involved in estradiol (E2)-induced SRC-3 phosphorylation and found that this occurs only when either activated estrogen receptor α (ERα) or activated ERβ is present. Both the activation function 1 and the ligand binding domains of ERα are required for maximal induction. Mutations in the coactivator binding groove of the ERα ligand binding domain inhibit E2-stimulated SRC-3 phosphorylation, as do mutations in the nuclear receptor-interacting domain of SRC-3, suggesting that ERα must directly contact SRC-3 for this posttranslational modification to take place. A transcriptionally inactive ERα mutant which localizes to the cytoplasm supports E2-induced SRC-3 phosphorylation. Mutations of the ERα DNA binding domain did not block this rapid E2-dependent SRC-3 phosphorylation. Together these data demonstrate that E2-induced SRC-3 phosphorylation is dependent on a direct interaction between SRC-3 and ERα and can occur outside of the nucleus. Our results provide evidence for an early nongenomic action of ER on SRC-3 that supports the well-established downstream genomic roles of estrogen and coactivators.

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