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Ma X, Xu S, Zhou Y, Zhang Q, Yang H, Wan B, Yang Y, Miao Z, Xu X. Targeting Nr2e3 to Modulate Tet2 Expression: Therapeutic Potential for Depression Treatment. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2400726. [PMID: 38881534 DOI: 10.1002/advs.202400726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 06/01/2024] [Indexed: 06/18/2024]
Abstract
Epigenetic mechanisms such as DNA methylation and hydroxymethylation play a significant role in depression. This research has shown that Ten-eleven translocation 2 (Tet2) deficiency prompts depression-like behaviors, but Tet2's transcriptional regulation remains unclear. In the study, bioinformatics is used to identify nuclear receptor subfamily 2 group E member 3 (Nr2e3) as a potential Tet2 regulator. Nr2e3 is found to enhance Tet2's transcriptional activity by binding to its promoter region. Nr2e3 knockdown in mouse hippocampus leads to reduced Tet2 expression, depression-like behaviors, decreased hydroxymethylation of synaptic genes, and downregulation of synaptic proteins like postsynaptic density 95 KDa (PSD95) and N-methy-d-aspartate receptor 1 (NMDAR1). Fewer dendritic spines are also observed. Nr2e3 thus appears to play an antidepressant role under stress. In search of potential treatments, small molecule compounds to increase Nr2e3 expression are screened. Azacyclonal (AZA) is found to enhance the Nr2e3/Tet2 pathway and exhibited antidepressant effects in stressed mice, increasing PSD95 and NMDAR1 expression and dendritic spine density. This study illuminates Tet2's upstream regulatory mechanism, providing a new target for identifying early depression biomarkers and developing treatments.
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Affiliation(s)
- Xiaohua Ma
- Department of Neurology, the First Affiliated Hospital of Soochow University, Suzhou, 215000, China
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Shiyao Xu
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Yaohui Zhou
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Qian Zhang
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Hao Yang
- Department of Fetology, the First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Bo Wan
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Yong Yang
- Department of Psychiatry, the Affiliated Guangji Hospital of Soochow University, Suzhou, Jiangsu, 215000, China
| | - Zhigang Miao
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Xingshun Xu
- Department of Neurology, the First Affiliated Hospital of Soochow University, Suzhou, 215000, China
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou, Jiangsu, 215123, China
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Aísa-Marín I, Rovira Q, Díaz N, Calvo-López L, Vaquerizas JM, Marfany G. Specific photoreceptor cell fate pathways are differentially altered in NR2E3-associated diseases. Neurobiol Dis 2024; 194:106463. [PMID: 38485095 DOI: 10.1016/j.nbd.2024.106463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 03/01/2024] [Accepted: 03/02/2024] [Indexed: 03/21/2024] Open
Abstract
Mutations in NR2E3, a gene encoding an orphan nuclear transcription factor, cause two retinal dystrophies with a distinct phenotype, but the precise role of NR2E3 in rod and cone transcriptional networks remains unclear. To dissect NR2E3 function, we performed scRNA-seq in the retinas of wildtype and two different Nr2e3 mouse models that show phenotypes similar to patients carrying NR2E3 mutations. Our results reveal that rod and cone populations are not homogeneous and can be separated into different sub-classes. We identify a previously unreported cone pathway that generates hybrid cones co-expressing both cone- and rod-related genes. In mutant retinas, this hybrid cone subpopulation is more abundant and includes a subpopulation of rods transitioning towards a cone cell fate. Hybrid photoreceptors with high misexpression of cone- and rod-related genes are prone to regulated necrosis. Overall, our results shed light on the role of NR2E3 in modulating photoreceptor differentiation towards cone and rod fates and explain how different mutations in NR2E3 lead to distinct visual disorders in humans.
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Affiliation(s)
- Izarbe Aísa-Marín
- Department de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona 08028, Spain; IBUB-IRSJD, Institut de Biomedicina de la Universitat de Barcelona-Institut de Recerca Sant Joan de Déu, Barcelona 08028, Spain; CIBERER, Instituto de Salud Carlos III, Barcelona 08028, Spain
| | - Quirze Rovira
- Max-Planck-Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Noelia Díaz
- Max-Planck-Institute for Molecular Biomedicine, Münster 48149, Germany
| | - Laura Calvo-López
- Department de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona 08028, Spain
| | - Juan M Vaquerizas
- Max-Planck-Institute for Molecular Biomedicine, Münster 48149, Germany; MRC London Institute of Medical Sciences, Institute of Clinical Sciences, Imperial College London, London W12 0NN, UK.; Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK.
| | - Gemma Marfany
- Department de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona 08028, Spain; IBUB-IRSJD, Institut de Biomedicina de la Universitat de Barcelona-Institut de Recerca Sant Joan de Déu, Barcelona 08028, Spain; CIBERER, Instituto de Salud Carlos III, Barcelona 08028, Spain; DBGen Ocular Genomics, Barcelona 08028, Spain.
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3
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Toms M, Ward N, Moosajee M. Nuclear Receptor Subfamily 2 Group E Member 3 (NR2E3): Role in Retinal Development and Disease. Genes (Basel) 2023; 14:1325. [PMID: 37510230 PMCID: PMC10379133 DOI: 10.3390/genes14071325] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/11/2023] [Accepted: 06/19/2023] [Indexed: 07/30/2023] Open
Abstract
NR2E3 is a nuclear hormone receptor gene required for the correct development of the retinal rod photoreceptors. Expression of NR2E3 protein in rod cell precursors suppresses cone-specific gene expression and, in concert with other transcription factors including NRL, activates the expression of rod-specific genes. Pathogenic variants involving NR2E3 cause a spectrum of retinopathies, including enhanced S-cone syndrome, Goldmann-Favre syndrome, retinitis pigmentosa, and clumped pigmentary retinal degeneration, with limited evidence of genotype-phenotype correlations. A common feature of NR2E3-related disease is an abnormally high number of cone photoreceptors that are sensitive to short wavelength light, the S-cones. This characteristic has been supported by mouse studies, which have also revealed that loss of Nr2e3 function causes photoreceptors to develop as cells that are intermediate between rods and cones. While there is currently no available cure for NR2E3-related retinopathies, there are a number of emerging therapeutic strategies under investigation, including the use of viral gene therapy and gene editing, that have shown promise for the future treatment of patients with NR2E3 variants and other inherited retinal diseases. This review provides a detailed overview of the current understanding of the role of NR2E3 in normal development and disease, and the associated clinical phenotypes, animal models, and therapeutic studies.
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Affiliation(s)
- Maria Toms
- Development, Ageing and Disease, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Ocular Genomics and Therapeutics, The Francis Crick Institute, London NW1 1AT, UK
| | - Natasha Ward
- Development, Ageing and Disease, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - Mariya Moosajee
- Development, Ageing and Disease, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Ocular Genomics and Therapeutics, The Francis Crick Institute, London NW1 1AT, UK
- Department of Genetics, Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Department of Ophthalmology, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
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da Palma MM, Marra M, Pennesi ME. A DOUBLE HYPERAUTOFLUORESCENT RING IN A 33-YEAR-OLD-FEMALE PATIENT. Retin Cases Brief Rep 2023; 17:S15-S18. [PMID: 36067420 PMCID: PMC10292570 DOI: 10.1097/icb.0000000000001337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
PURPOSE To describe the clinical phenotype and molecular diagnosis of a patient with atypical presentation of enhanced S-cone syndrome. METHODS This is a case report of a patient who underwent best-corrected visual acuity, slit-lamp exam, fundus examination, autofluorescence, optical coherence tomography, kinetic perimetry, and full-field electroretinography. Genetic testing was performed via next-generation sequencing. RESULTS A 33-year-old female patient presented with mild nyctalopia, but normal rod function measured by electroretinogram and foveoschisis on optical coherence tomography. She also presented a double hyperautofluorescent ring on autofluorescence. Genetic testing found a pathogenic variant c.925C>G (p.Arg309Gly) and a likely pathogenic variant c.299C>T (p.Arg77Trp) in NR2E3 gene. CONCLUSION Enhanced S-cone syndrome may present without the pathognomonic findings of decreased rod function on electroretinogram, suggesting the importance of genetic testing in retinal diseases for diagnosis.
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Affiliation(s)
- Mariana M. da Palma
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon; and
- Department of Ophthalmology and Visual Science, Federal University of São Paulo, São Paulo, Brazil
| | - Molly Marra
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon; and
| | - Mark E. Pennesi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon; and
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Sun C, Chen S. Disease-causing mutations in genes encoding transcription factors critical for photoreceptor development. Front Mol Neurosci 2023; 16:1134839. [PMID: 37181651 PMCID: PMC10172487 DOI: 10.3389/fnmol.2023.1134839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 04/04/2023] [Indexed: 05/16/2023] Open
Abstract
Photoreceptor development of the vertebrate visual system is controlled by a complex transcription regulatory network. OTX2 is expressed in the mitotic retinal progenitor cells (RPCs) and controls photoreceptor genesis. CRX that is activated by OTX2 is expressed in photoreceptor precursors after cell cycle exit. NEUROD1 is also present in photoreceptor precursors that are ready to specify into rod and cone photoreceptor subtypes. NRL is required for the rod fate and regulates downstream rod-specific genes including the orphan nuclear receptor NR2E3 which further activates rod-specific genes and simultaneously represses cone-specific genes. Cone subtype specification is also regulated by the interplay of several transcription factors such as THRB and RXRG. Mutations in these key transcription factors are responsible for ocular defects at birth such as microphthalmia and inherited photoreceptor diseases such as Leber congenital amaurosis (LCA), retinitis pigmentosa (RP) and allied dystrophies. In particular, many mutations are inherited in an autosomal dominant fashion, including the majority of missense mutations in CRX and NRL. In this review, we describe the spectrum of photoreceptor defects that are associated with mutations in the above-mentioned transcription factors, and summarize the current knowledge of molecular mechanisms underlying the pathogenic mutations. At last, we deliberate the outstanding gaps in our understanding of the genotype-phenotype correlations and outline avenues for future research of the treatment strategies.
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Affiliation(s)
- Chi Sun
- Department of Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO, United States
- *Correspondence: Chi Sun,
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, Washington University in St. Louis, St. Louis, MO, United States
- Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO, United States
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Connor B, Titialii-Torres K, Rockenhaus AE, Passamonte S, Morris AC, Lee YS. Biliverdin regulates NR2E3 and zebrafish retinal photoreceptor development. Sci Rep 2022; 12:7310. [PMID: 35508617 PMCID: PMC9068610 DOI: 10.1038/s41598-022-11502-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 04/25/2022] [Indexed: 11/30/2022] Open
Abstract
NR2E3 is an orphan nuclear receptor whose loss-of-function causes abnormal retinal photoreceptor development and degeneration. However, despite that many nuclear receptors are regulated by binding of small molecule ligands, biological small molecule ligands regulating NR2E3 have not been identified. Identification of an endogenous NR2E3 ligand might reveal a previously unrecognized component contributing to retinal development and maintenance. Here we report that biliverdin, a conserved green pigment from heme catabolism, regulates NR2E3 and is necessary for zebrafish retinal photoreceptor development. Biliverdin from retinal extracts specifically bound to NR2E3’s ligand-binding domain and induced NR2E3-dependent reporter gene expression. Inhibition of biliverdin synthesis decreased photoreceptor cell populations in zebrafish larvae, and this phenotype was alleviated by exogenously supplied biliverdin. Thus, biliverdin is an endogenous small molecule ligand for NR2E3 and a component necessary for the proper development of photoreceptor cells. This result suggests a possible role of heme metabolism in the regulation of retinal photoreceptor cell development.
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Affiliation(s)
- Blaine Connor
- Department of Biology, Johns Hopkins University, Baltimore, MD, 21218, USA
| | | | - Abigail E Rockenhaus
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Samuel Passamonte
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
| | - Ann C Morris
- Department of Biology, University of Kentucky, Lexington, KY, 40506, USA
| | - Young-Sam Lee
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY, 40536, USA.
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Structural overview and perspectives of the nuclear receptors, a major family as the direct targets for small-molecule drugs. Acta Biochim Biophys Sin (Shanghai) 2021; 54:12-24. [PMID: 35130630 PMCID: PMC9909358 DOI: 10.3724/abbs.2021001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The nuclear receptors (NRs) are an evolutionarily related family of transcription factors, which share certain common structural characteristics and regulate the expressions of various genes by recognizing different response elements. NRs play important roles in cell differentiation, proliferation, survival and apoptosis, rendering them indispensable in many physiological activities including growth and metabolism. As a result, dysfunctions of NRs are closely related to a variety of diseases, such as diabetes, obesity, infertility, inflammation, the Alzheimer's disease, cardiovascular diseases, prostate and breast cancers. Meanwhile, small-molecule drugs directly targeting NRs have been widely used in the treatment of above diseases. Here we summarize recent progress in the structural biology studies of NR family proteins. Compared with the dozens of structures of isolated DNA-binding domains (DBDs) and the striking more than a thousand of structures of isolated ligand-binding domains (LBDs) accumulated in the Protein Data Bank (PDB) over thirty years, by now there are only a small number of multi-domain NR complex structures, which reveal the integration of different NR domains capable of the allosteric signal transduction, or the detailed interactions between NR and various coregulator proteins. On the other hand, the structural information about several orphan NRs is still totally unavailable, hindering the further understanding of their functions. The fast development of new technologies in structural biology will certainly help us gain more comprehensive information of NR structures, inspiring the discovery of novel NR-targeting drugs with a new binding site beyond the classic LBD pockets and/or a new mechanism of action.
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8
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Nelson AT, Wang Y, Nelson ER. TLX, an Orphan Nuclear Receptor With Emerging Roles in Physiology and Disease. Endocrinology 2021; 162:6360449. [PMID: 34463725 PMCID: PMC8462384 DOI: 10.1210/endocr/bqab184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Indexed: 12/14/2022]
Abstract
TLX (NR2E1), an orphan member of the nuclear receptor superfamily, is a transcription factor that has been described to be generally repressive in nature. It has been implicated in several aspects of physiology and disease. TLX is best known for its ability to regulate the proliferation of neural stem cells and retinal progenitor cells. Dysregulation, overexpression, or loss of TLX expression has been characterized in numerous studies focused on a diverse range of pathological conditions, including abnormal brain development, psychiatric disorders, retinopathies, metabolic disease, and malignant neoplasm. Despite the lack of an identified endogenous ligand, several studies have described putative synthetic and natural TLX ligands, suggesting that this receptor may serve as a therapeutic target. Therefore, this article aims to briefly review what is known about TLX structure and function in normal physiology, and provide an overview of TLX in regard to pathological conditions. Particular emphasis is placed on TLX and cancer, and the potential utility of this receptor as a therapeutic target.
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Affiliation(s)
- Adam T Nelson
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Yu Wang
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Erik R Nelson
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
- Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
- Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
- University of Illinois Cancer Center, University of Illinois at Chicago, Chicago, Illinois 60612, USA
- Carl R. Woese Institute for Genomic Biology, Anticancer Discovery from Pets to People Theme, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
- Correspondence: Erik R. Nelson, PhD, Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, 407 S Goodwin Ave (MC-114), Urbana, IL 61801, USA.
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Willems S, Zaienne D, Merk D. Targeting Nuclear Receptors in Neurodegeneration and Neuroinflammation. J Med Chem 2021; 64:9592-9638. [PMID: 34251209 DOI: 10.1021/acs.jmedchem.1c00186] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nuclear receptors, also known as ligand-activated transcription factors, regulate gene expression upon ligand signals and present as attractive therapeutic targets especially in chronic diseases. Despite the therapeutic relevance of some nuclear receptors in various pathologies, their potential in neurodegeneration and neuroinflammation is insufficiently established. This perspective gathers preclinical and clinical data for a potential role of individual nuclear receptors as future targets in Alzheimer's disease, Parkinson's disease, and multiple sclerosis, and concomitantly evaluates the level of medicinal chemistry targeting these proteins. Considerable evidence suggests the high promise of ligand-activated transcription factors to counteract neurodegenerative diseases with a particularly high potential of several orphan nuclear receptors. However, potent tools are lacking for orphan receptors, and limited central nervous system exposure or insufficient selectivity also compromises the suitability of well-studied nuclear receptor ligands for functional studies. Medicinal chemistry efforts are needed to develop dedicated high-quality tool compounds for the therapeutic validation of nuclear receptors in neurodegenerative pathologies.
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Affiliation(s)
- Sabine Willems
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
| | - Daniel Zaienne
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
| | - Daniel Merk
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt, Germany
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A structural signature motif enlightens the origin and diversification of nuclear receptors. PLoS Genet 2021; 17:e1009492. [PMID: 33882063 PMCID: PMC8092661 DOI: 10.1371/journal.pgen.1009492] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 05/03/2021] [Accepted: 03/15/2021] [Indexed: 12/11/2022] Open
Abstract
Nuclear receptors are ligand-activated transcription factors that modulate gene regulatory networks from embryonic development to adult physiology and thus represent major targets for clinical interventions in many diseases. Most nuclear receptors function either as homodimers or as heterodimers. The dimerization is crucial for gene regulation by nuclear receptors, by extending the repertoire of binding sites in the promoters or the enhancers of target genes via combinatorial interactions. Here, we focused our attention on an unusual structural variation of the α-helix, called π-turn that is present in helix H7 of the ligand-binding domain of RXR and HNF4. By tracing back the complex evolutionary history of the π-turn, we demonstrate that it was present ancestrally and then independently lost in several nuclear receptor lineages. Importantly, the evolutionary history of the π-turn motif is parallel to the evolutionary diversification of the nuclear receptor dimerization ability from ancestral homodimers to derived heterodimers. We then carried out structural and biophysical analyses, in particular through point mutation studies of key RXR signature residues and showed that this motif plays a critical role in the network of interactions stabilizing homodimers. We further showed that the π-turn was instrumental in allowing a flexible heterodimeric interface of RXR in order to accommodate multiple interfaces with numerous partners and critical for the emergence of high affinity receptors. Altogether, our work allows to identify a functional role for the π-turn in oligomerization of nuclear receptors and reveals how this motif is linked to the emergence of a critical biological function. We conclude that the π-turn can be viewed as a structural exaptation that has contributed to enlarging the functional repertoire of nuclear receptors. The origin of novelties is a central topic in evolutionary biology. A fundamental question is how organisms constrained by natural selection can divert from existing schemes to set up novel structures or pathways. Among the most important strategies are exaptations, which represent pre-adaptation strategies. Many examples exist in biology, at both morphological and molecular levels, such as the one reported here that focuses on an unusual structural feature called the π-turn. It is found in the structure of the most ancestral nuclear receptors RXR and HNF4. The analyses trace back the complex evolutionary history of the π-turn to more than 500 million years ago, before the Cambrian explosion and show that this feature was essential for the heterodimerization capacity of RXR. Nuclear receptor lineages that emerged later in evolution lost the π-turn. We demonstrate here that this loss in nuclear receptors that heterodimerize with RXR was critical for the emergence of high affinity receptors, such as the vitamin D and the thyroid hormone receptors. On the other hand, the conserved π-turn in RXR allowed it to accommodate multiple heterodimer interfaces with numerous partners. This structural exaptation allowed for the remarkable diversification of nuclear receptors.
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Diakatou M, Dubois G, Erkilic N, Sanjurjo-Soriano C, Meunier I, Kalatzis V. Allele-Specific Knockout by CRISPR/Cas to Treat Autosomal Dominant Retinitis Pigmentosa Caused by the G56R Mutation in NR2E3. Int J Mol Sci 2021; 22:ijms22052607. [PMID: 33807610 PMCID: PMC7961898 DOI: 10.3390/ijms22052607] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 12/18/2022] Open
Abstract
Retinitis pigmentosa (RP) is an inherited retinal dystrophy that causes progressive vision loss. The G56R mutation in NR2E3 is the second most common mutation causing autosomal dominant (ad) RP, a transcription factor that is essential for photoreceptor development and maintenance. The G56R variant is exclusively responsible for all cases of NR2E3-associated adRP. Currently, there is no treatment for NR2E3-related or, other, adRP, but genome editing holds promise. A pertinent approach would be to specifically knockout the dominant mutant allele, so that the wild type allele can perform unhindered. In this study, we developed a CRISPR/Cas strategy to specifically knockout the mutant G56R allele of NR2E3 and performed a proof-of-concept study in induced pluripotent stem cells (iPSCs) of an adRP patient. We demonstrate allele-specific knockout of the mutant G56R allele in the absence of off-target events. Furthermore, we validated this knockout strategy in an exogenous overexpression system. Accordingly, the mutant G56R-CRISPR protein was truncated and mis-localized to the cytosol in contrast to the (peri)nuclear localizations of wild type or G56R NR2E3 proteins. Finally, we show, for the first time, that G56R iPSCs, as well as G56R-CRISPR iPSCs, can differentiate into NR2E3-expressing retinal organoids. Overall, we demonstrate that G56R allele-specific knockout by CRISPR/Cas could be a clinically relevant approach to treat NR2E3-associated adRP.
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Affiliation(s)
- Michalitsa Diakatou
- INM, University of Montpellier, Inserm, 34091 Montpellier, France; (M.D.); (G.D.); (N.E.); (C.S.-S.); (I.M.)
| | - Gregor Dubois
- INM, University of Montpellier, Inserm, 34091 Montpellier, France; (M.D.); (G.D.); (N.E.); (C.S.-S.); (I.M.)
| | - Nejla Erkilic
- INM, University of Montpellier, Inserm, 34091 Montpellier, France; (M.D.); (G.D.); (N.E.); (C.S.-S.); (I.M.)
- National Reference Centre for Inherited Sensory Diseases, University of Montpellier, CHU, 34295 Montpellier, France
| | - Carla Sanjurjo-Soriano
- INM, University of Montpellier, Inserm, 34091 Montpellier, France; (M.D.); (G.D.); (N.E.); (C.S.-S.); (I.M.)
| | - Isabelle Meunier
- INM, University of Montpellier, Inserm, 34091 Montpellier, France; (M.D.); (G.D.); (N.E.); (C.S.-S.); (I.M.)
- National Reference Centre for Inherited Sensory Diseases, University of Montpellier, CHU, 34295 Montpellier, France
| | - Vasiliki Kalatzis
- INM, University of Montpellier, Inserm, 34091 Montpellier, France; (M.D.); (G.D.); (N.E.); (C.S.-S.); (I.M.)
- Correspondence:
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de Carvalho ER, Robson AG, Arno G, Boon CJF, Webster AA, Michaelides M. Enhanced S-Cone Syndrome: Spectrum of Clinical, Imaging, Electrophysiologic, and Genetic Findings in a Retrospective Case Series of 56 Patients. Ophthalmol Retina 2021; 5:195-214. [PMID: 32679203 PMCID: PMC7861019 DOI: 10.1016/j.oret.2020.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/06/2020] [Accepted: 07/09/2020] [Indexed: 11/19/2022]
Abstract
PURPOSE To describe the detailed phenotype, long-term clinical course, clinical variability, and genotype of patients with enhanced S-cone syndrome (ESCS). DESIGN Retrospective case series. PARTICIPANTS Fifty-six patients with ESCS. METHODS Clinical history, examination, imaging, and electrophysiologic findings of 56 patients (age range, 1-75 years) diagnosed with ESCS were reviewed. Diagnosis was established by molecular confirmation of disease-causing variants in the NR2E3 gene (n = 38) or by diagnostic full-field electroretinography findings (n = 18). MAIN OUTCOME MEASURES Age at onset of visual symptoms, best-corrected visual acuity (BCVA), quantitative age-related electrophysiologic decline, and imaging findings. RESULTS Mean age at onset of visual symptoms was 4.0 years, and median age at presentation was 20.5 years, with mean follow-up interval being 6.1 years. Six patients were assessed once. Disease-causing variants in NR2E3 were identified in 38 patients. Mean BCVA of the better-seeing eye was 0.32 logarithm of the minimum angle of resolution (logMAR) at baseline and 0.39 logMAR at follow-up. In most eyes (76% [76/100]), BCVA remained stable, with a mean BCVA change of 0.07 logMAR during follow-up. Nyctalopia was the most common initial symptom, reported in 92.9% of patients (52/56). Clinical findings were highly variable and included foveomacular schisis (41.1% [26/56]), yellow-white dots (57.1% [32/56]), nummular pigmentation (85.7% [48/56]), torpedo-like lesions (10.7% [6/56]), and circumferential subretinal fibrosis (7.1% [4/56]). Macular and peripheral patterns of autofluorescence were classified as (1) minimal change, (2) hypoautofluorescent (mild diffuse, moderate speckled, moderate diffuse, or advanced), or (3) hyperautofluorescent flecks. One patient showed undetectable electroretinography findings; quantification of main electroretinography components in all other patients revealed amplitude and peak time variability but with pathognomonic electroretinography features. The main electroretinography components showed evidence of age-related worsening over 6.7 decades, at a rate indistinguishable from that seen in unaffected control participants. Eighteen sequence variants in NR2E3 were identified, including 4 novel missense changes. CONCLUSIONS Enhanced S-cone syndrome has a highly variable phenotype with relative clinical and imaging stability over time. Most electroretinography findings have pathognomonic features, but quantitative assessment reveals variability and a normal mean rate of age-related decline, consistent with largely nonprogressive peripheral retinal dysfunction.
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Affiliation(s)
- Emanuel R de Carvalho
- Moorfields Eye Hospital, London, United Kingdom; Department of Ophthalmology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Anthony G Robson
- Moorfields Eye Hospital, London, United Kingdom; Department of Ophthalmology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Gavin Arno
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Camiel J F Boon
- Department of Ophthalmology, Amsterdam University Medical Centers, Amsterdam, The Netherlands; Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew A Webster
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Michel Michaelides
- Moorfields Eye Hospital, London, United Kingdom; UCL Institute of Ophthalmology, University College London, London, United Kingdom.
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Griffett K, Bedia-Diaz G, Hegazy L, de Vera IMS, Wanninayake US, Billon C, Koelblen T, Wilhelm ML, Burris TP. The Orphan Nuclear Receptor TLX Is a Receptor for Synthetic and Natural Retinoids. Cell Chem Biol 2020; 27:1272-1284.e4. [DOI: 10.1016/j.chembiol.2020.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/08/2020] [Accepted: 07/17/2020] [Indexed: 12/13/2022]
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14
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Nr2e3 functional domain ablation by CRISPR-Cas9D10A identifies a new isoform and generates retinitis pigmentosa and enhanced S-cone syndrome models. Neurobiol Dis 2020; 146:105122. [PMID: 33007388 DOI: 10.1016/j.nbd.2020.105122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/23/2020] [Accepted: 09/25/2020] [Indexed: 12/18/2022] Open
Abstract
Mutations in NR2E3 cause retinitis pigmentosa (RP) and enhanced S-cone syndrome (ESCS) in humans. This gene produces a large isoform encoded in 8 exons and a previously unreported shorter isoform of 7 exons, whose function is unknown. We generated two mouse models by targeting exon 8 of Nr2e3 using CRISPR/Cas9-D10A nickase. Allele Δ27 is an in-frame deletion of 27 bp that ablates the dimerization domain H10, whereas allele ΔE8 (full deletion of exon 8) produces only the short isoform, which lacks the C-terminal part of the ligand binding domain (LBD) that encodes both H10 and the AF2 domain involved in the Nr2e3 repressor activity. The Δ27 mutant shows developmental alterations and a non-progressive electrophysiological dysfunction that resembles the ESCS phenotype. The ΔE8 mutant exhibits progressive retinal degeneration, as occurs in human RP patients. Our mutants suggest a role for Nr2e3 as a cone-patterning regulator and provide valuable models for studying mechanisms of NR2E3-associated retinal dystrophies and evaluating potential therapies.
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15
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Minnella AM, Pagliei V, Savastano MC, Federici M, Bertelli M, Maltese PE, Placidi G, Corbo G, Falsini B, Caporossi A. Swept source optical coherence tomography and optical coherence tomography angiography in pediatric enhanced S-cone syndrome: a case report. J Med Case Rep 2018; 12:287. [PMID: 30285900 PMCID: PMC6169104 DOI: 10.1186/s13256-018-1819-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 08/28/2018] [Indexed: 11/10/2022] Open
Abstract
Background Enhanced S-cone syndrome is an autosomal recessive retinal dystrophy related to a defect in a nuclear receptor gene (NR2E3) that leads to alteration in cells development from rod to S-cone. This retinal dystrophy may be associated with retinal schisis. The aim of this report is to describe structural optical coherence tomography and optical coherence tomography angiography features in a case of enhanced S-cone syndrome associated with macular schisis. Case presentation A Caucasian 13-year-old girl underwent measurement of best corrected visual acuity, ophthalmoscopic evaluation, and fundus autofluorescence examination. Photopic and scotopic electroretinography were carried out as well. Enhanced S-cone syndrome was suspected on the basis of clinical and electrophysiological findings. Structural optical coherence tomography and optical coherence tomography angiography allowed the further characterization of the associated macular schisis. Genetic analysis not only confirmed the diagnosis but increased the clinical novelty of this case report by showing two variations in the NR2E3 gene probably related to the phenotype: a missense variation c.1118T>C which leads to the substitution of leucine with proline in amino acid position 373, and c.349+5G>C, which involves a gene sequence near a splicing site. Conclusions Swept source structural optical coherence tomography (B scans and “en face” images) and optical coherence tomography angiography allowed the observation of retinal structural details and the involvement of each retinal layer and capillary plexus in enhanced S-cone syndrome. Of interest, neither of the two NR2E3 gene variants found in this case report have been linked to any form of retinopathy.
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Affiliation(s)
- Angelo Maria Minnella
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy.
| | - Valeria Pagliei
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Maria Cristina Savastano
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Matteo Federici
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | | | | | - Giorgio Placidi
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Giovanni Corbo
- Department of Ophthalmology, Università La Sapienza, Rome, Italy
| | - Benedetto Falsini
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
| | - Aldo Caporossi
- Institute of Ophthalmology, Università Cattolica del Sacro Cuore - Fondazione Policlinico Universitario A. Gemelli-IRCCS, Rome, Italy
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16
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Loss of NR2E3 represses AHR by LSD1 reprogramming, is associated with poor prognosis in liver cancer. Sci Rep 2017; 7:10662. [PMID: 28878246 PMCID: PMC5587550 DOI: 10.1038/s41598-017-11106-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 08/18/2017] [Indexed: 11/15/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) plays crucial roles in inflammation, metabolic disorder, and cancer. However, the molecular mechanisms regulating AHR expression remain unknown. Here, we found that an orphan nuclear NR2E3 maintains AHR expression, and forms an active transcriptional complex with transcription factor Sp1 and coactivator GRIP1 in MCF-7 human breast and HepG2 liver cancer cell lines. NR2E3 loss promotes the recruitment of LSD1, a histone demethylase of histone 3 lysine 4 di-methylation (H3K4me2), to the AHR gene promoter region, resulting in repression of AHR expression. AHR expression and responsiveness along with H3K4me2 were significantly reduced in the livers of Nr2e3rd7 (Rd7) mice that express low NR2E3 relative to the livers of wild-type mice. SP2509, an LSD1 inhibitor, fully restored AHR expression and H3K4me2 levels in Rd7 mice. Lastly, we demonstrated that both AHR and NR2E3 are significantly associated with good clinical outcomes in liver cancer. Together, our results reveal a novel link between NR2E3, AHR, and liver cancer via LSD1-mediated H3K4me2 histone modification in liver cancer development.
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17
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Nakamura PA, Tang S, Shimchuk AA, Ding S, Reh TA. Potential of Small Molecule-Mediated Reprogramming of Rod Photoreceptors to Treat Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2017; 57:6407-6415. [PMID: 27893103 PMCID: PMC5134355 DOI: 10.1167/iovs.16-20177] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Mutations in rod photoreceptor genes can cause retinitis pigmentosa (RP). Rod gene expression is regulated by the nuclear hormone receptor, Nr2e3. Genetic deletion of Nr2e3 reprograms rods into cells that resemble cone photoreceptors, and might therefore prevent their death from some forms of RP. There are no identified ligands for Nr2e3; however, reverse agonists might mimic the genetic rescue effect and may be therapeutically useful for the treatment of RP. Methods We screened for small molecule modulators of Nr2e3 using primary retinal cell cultures and characterized the most potent, which we have named photoregulin1 (PR1), in vitro and in vivo. We also tested the ability of PR1 to slow the progression of photoreceptor degeneration in two common mouse models of autosomal dominant RP, the RhoP23H and the Pde6brd1 mutations. Results In developing retina, PR1 causes a decrease in rod gene expression and an increase in S opsin+ cones. Photoregulin1 continues to inhibit rod gene expression in adult mice. When applied to two mouse models of RP, PR1 slows the degeneration of photoreceptors. Conclusions Chemical compounds identified as modulators of Nr2e3 activity may be useful for the treatment of RP through their effects on expression of disease-causing mutant genes.
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Affiliation(s)
- Paul A Nakamura
- Department of Biological Structure, University of Washington, School of Medicine, Seattle, Washington, United States
| | - Shibing Tang
- University of California-San Francisco, UCSF School of Pharmacy, Department of Pharmaceutical Chemistry, San Francisco California, United States
| | - Andy A Shimchuk
- Department of Biological Structure, University of Washington, School of Medicine, Seattle, Washington, United States
| | - Sheng Ding
- University of California-San Francisco, UCSF School of Pharmacy, Department of Pharmaceutical Chemistry, San Francisco California, United States
| | - Thomas A Reh
- Department of Biological Structure, University of Washington, School of Medicine, Seattle, Washington, United States
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18
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Fulton J, Mazumder B, Whitchurch JB, Monteiro CJ, Collins HM, Chan CM, Clemente MP, Hernandez-Quiles M, Stewart EA, Amoaku WM, Moran PM, Mongan NP, Persson JL, Ali S, Heery DM. Heterodimers of photoreceptor-specific nuclear receptor (PNR/NR2E3) and peroxisome proliferator-activated receptor-γ (PPARγ) are disrupted by retinal disease-associated mutations. Cell Death Dis 2017; 8:e2677. [PMID: 28300834 PMCID: PMC5386588 DOI: 10.1038/cddis.2017.98] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 01/19/2017] [Accepted: 01/23/2017] [Indexed: 12/30/2022]
Abstract
Photoreceptor-specific nuclear receptor (PNR/NR2E3) and Tailless homolog (TLX/NR2E1) are human orthologs of the NR2E group, a subgroup of phylogenetically related members of the nuclear receptor (NR) superfamily of transcription factors. We assessed the ability of these NRs to form heterodimers with other members of the human NRs representing all major subgroups. The TLX ligand-binding domain (LBD) did not appear to form homodimers or interact directly with any other NR tested. The PNR LBD was able to form homodimers, but also exhibited robust interactions with the LBDs of peroxisome proliferator-activated receptor-γ (PPARγ)/NR1C3 and thyroid hormone receptor b (TRb) TRβ/NR1A2. The binding of PNR to PPARγ was specific for this paralog, as no interaction was observed with the LBDs of PPARα/NR1C1 or PPARδ/NR1C2. In support of these findings, PPARγ and PNR were found to be co-expressed in human retinal tissue extracts and could be co-immunoprecipitated as a native complex. Selected sequence variants in the PNR LBD associated with human retinopathies, or a mutation in the dimerization region of PPARγ LBD associated with familial partial lipodystrophy type 3, were found to disrupt PNR/PPARγ complex formation. Wild-type PNR, but not a PNR309G mutant, was able to repress PPARγ-mediated transcription in reporter assays. In summary, our results reveal novel heterodimer interactions in the NR superfamily, suggesting previously unknown functional interactions of PNR with PPARγ and TRβ that have potential importance in retinal development and disease.
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Affiliation(s)
- Joel Fulton
- School of Pharmacy, University of Nottingham, Nottingham, UK
| | - Bismoy Mazumder
- School of Pharmacy, University of Nottingham, Nottingham, UK
| | | | | | | | - Chun M Chan
- School of Pharmacy, University of Nottingham, Nottingham, UK
| | | | | | - Elizabeth A Stewart
- Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK
| | - Winfried M Amoaku
- Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK
| | - Paula M Moran
- School of Psychology, University of Nottingham, Nottingham, UK
| | - Nigel P Mongan
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
- Department of Pharmacology, Weill Cornell Medicine, New York, NY, USA
| | - Jenny L Persson
- Division of Experimental Cancer Research, Department of Translational Medicine, Lund University, Clinical Research Centre, Malmö, Sweden
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Simak Ali
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - David M Heery
- School of Pharmacy, University of Nottingham, Nottingham, UK
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19
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Anami Y, Shimizu N, Ekimoto T, Egawa D, Itoh T, Ikeguchi M, Yamamoto K. Apo- and Antagonist-Binding Structures of Vitamin D Receptor Ligand-Binding Domain Revealed by Hybrid Approach Combining Small-Angle X-ray Scattering and Molecular Dynamics. J Med Chem 2016; 59:7888-900. [DOI: 10.1021/acs.jmedchem.6b00682] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yasuaki Anami
- Laboratory
of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Nobutaka Shimizu
- Photon
Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Toru Ekimoto
- Graduate
School of Medical Life Science, Yokohama City University, 1-7-29
Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Daichi Egawa
- Laboratory
of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Toshimasa Itoh
- Laboratory
of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Mitsunori Ikeguchi
- Graduate
School of Medical Life Science, Yokohama City University, 1-7-29
Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Keiko Yamamoto
- Laboratory
of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
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20
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Zhi X, Zhou XE, Melcher K, Xu HE. Structures and regulation of non-X orphan nuclear receptors: A retinoid hypothesis. J Steroid Biochem Mol Biol 2016; 157:27-40. [PMID: 26159912 DOI: 10.1016/j.jsbmb.2015.06.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 06/10/2015] [Accepted: 06/16/2015] [Indexed: 12/28/2022]
Abstract
Nuclear receptors are defined as a family of ligand regulated transcription factors [1-6]. While this definition reflects that ligand binding is a key property of nuclear receptors, it is still a heated subject of debate if all the nuclear receptors (48 human members) can bind ligands (ligands referred here to both physiological and synthetic ligands). Recent studies in nuclear receptor structure biology and pharmacology have undoubtedly increased our knowledge of nuclear receptor functions and their regulation. As a result, they point to new avenues for the discovery and development of nuclear receptor regulators, including nuclear receptor ligands. Here we review the recent literature on orphan nuclear receptor structural analysis and ligand identification, particularly on the orphan nuclear receptors that do not heterodimerize with retinoid X receptors, which we term as non-X orphan receptors. We also propose a speculative "retinoid hypothesis" for a subset of non-X orphan nuclear receptors, which we hope to help shed light on orphan nuclear receptor biology and drug discovery. This article is part of a Special Issue entitled 'Orphan Nuclear Receptors'.
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Affiliation(s)
- Xiaoyong Zhi
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave., N.E., Grand Rapids, MI 49503, USA; Autophagy Research Center, University of Texas Southwestern Medical Center, 6000Harry Hines Blvd., Dallas, TX 75390, USA.
| | - X Edward Zhou
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave., N.E., Grand Rapids, MI 49503, USA
| | - Karsten Melcher
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave., N.E., Grand Rapids, MI 49503, USA
| | - H Eric Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Ave., N.E., Grand Rapids, MI 49503, USA; VARI-SIMM Center, Key Laboratory of Receptor Research, Shanghai Institute of MateriaMedica, Chinese Academy of Sciences, Shanghai 201203, China.
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21
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Benod C, Villagomez R, Webb P. TLX: An elusive receptor. J Steroid Biochem Mol Biol 2016; 157:41-7. [PMID: 26554934 DOI: 10.1016/j.jsbmb.2015.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 06/30/2015] [Accepted: 11/04/2015] [Indexed: 12/11/2022]
Abstract
TLX (tailless receptor) is a member of the nuclear receptor superfamily and belongs to a class of nuclear receptors for which no endogenous or synthetic ligands have yet been identified. TLX is a promising therapeutic target in neurological disorders and brain tumors. Thus, regulatory ligands for TLX need to be identified to complete the validation of TLX as a useful target and would serve as chemical probes to pursue the study of this receptor in disease models. It has recently been proved that TLX is druggable. However, to identify potent and specific TLX ligands with desirable biological activity, a deeper understanding of where ligands bind, how they alter TLX conformation and of the mechanism by which TLX mediates the transcription of its target genes is needed. While TLX is in the process of escaping from orphanhood, future ligand design needs to progress in parallel with improved understanding of (i) the binding cavity or surfaces to target with small molecules on the TLX ligand binding domain and (ii) the nature of the TLX coregulators in particular cell and disease contexts. Both of these topics are discussed in this review.
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Affiliation(s)
- Cindy Benod
- Department of Genomic Medicine, Houston Methodist Research Institute (HMRI), 6670 Bertner Avenue, Houston, TX 77030, USA.
| | - Rosa Villagomez
- Department of Genomic Medicine, Houston Methodist Research Institute (HMRI), 6670 Bertner Avenue, Houston, TX 77030, USA
| | - Paul Webb
- Department of Genomic Medicine, Houston Methodist Research Institute (HMRI), 6670 Bertner Avenue, Houston, TX 77030, USA
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22
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Waugh DS. Crystal structures of MBP fusion proteins. Protein Sci 2016; 25:559-71. [PMID: 26682969 DOI: 10.1002/pro.2863] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 12/16/2015] [Indexed: 02/06/2023]
Abstract
Although chaperone-assisted protein crystallization remains a comparatively rare undertaking, the number of crystal structures of polypeptides fused to maltose-binding protein (MBP) that have been deposited in the Protein Data Bank (PDB) has grown dramatically during the past decade. Altogether, 102 fusion protein structures were detected by Basic Local Alignment Search Tool (BLAST) analysis. Collectively, these structures comprise a range of sizes, space groups, and resolutions that are typical of the PDB as a whole. While most of these MBP fusion proteins were equipped with short inter-domain linkers to increase their rigidity, fusion proteins with long linkers have also been crystallized. In some cases, surface entropy reduction mutations in MBP appear to have facilitated the formation of crystals. A comparison of the structures of fused and unfused proteins, where both are available, reveals that MBP-mediated structural distortions are very rare.
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Affiliation(s)
- David S Waugh
- Protein Engineering Section, Macromolecular Crystallography Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, Maryland, 21702-1201
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23
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Biophysical Characterization of a Vaccine Candidate against HIV-1: The Transmembrane and Membrane Proximal Domains of HIV-1 gp41 as a Maltose Binding Protein Fusion. PLoS One 2015; 10:e0136507. [PMID: 26295457 PMCID: PMC4546420 DOI: 10.1371/journal.pone.0136507] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 08/05/2015] [Indexed: 11/19/2022] Open
Abstract
The membrane proximal region (MPR, residues 649-683) and transmembrane domain (TMD, residues 684-705) of the gp41 subunit of HIV-1's envelope protein are highly conserved and are important in viral mucosal transmission, virus attachment and membrane fusion with target cells. Several structures of the trimeric membrane proximal external region (residues 662-683) of MPR have been reported at the atomic level; however, the atomic structure of the TMD still remains unknown. To elucidate the structure of both MPR and TMD, we expressed the region spanning both domains, MPR-TM (residues 649-705), in Escherichia coli as a fusion protein with maltose binding protein (MBP). MPR-TM was initially fused to the C-terminus of MBP via a 42 aa-long linker containing a TEV protease recognition site (MBP-linker-MPR-TM). Biophysical characterization indicated that the purified MBP-linker-MPR-TM protein was a monodisperse and stable candidate for crystallization. However, crystals of the MBP-linker-MPR-TM protein could not be obtained in extensive crystallization screens. It is possible that the 42 residue-long linker between MBP and MPR-TM was interfering with crystal formation. To test this hypothesis, the 42 residue-long linker was replaced with three alanine residues. The fusion protein, MBP-AAA-MPR-TM, was similarly purified and characterized. Significantly, both the MBP-linker-MPR-TM and MBP-AAA-MPR-TM proteins strongly interacted with broadly neutralizing monoclonal antibodies 2F5 and 4E10. With epitopes accessible to the broadly neutralizing antibodies, these MBP/MPR-TM recombinant proteins may be in immunologically relevant conformations that mimic a pre-hairpin intermediate of gp41.
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Khanal T, Kim D, Johnson A, Choubey D, Kim K. Deregulation of NR2E3, an orphan nuclear receptor, by benzo(a)pyrene-induced oxidative stress is associated with histone modification status change of the estrogen receptor gene promoter. Toxicol Lett 2015; 237:228-36. [PMID: 26149760 DOI: 10.1016/j.toxlet.2015.06.1708] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/05/2015] [Accepted: 06/22/2015] [Indexed: 10/23/2022]
Abstract
We previously reported that NR2E3, an orphan nuclear receptor, plays an important role in maintaining the basal expression of estrogen receptor α (ER) and that the NR2E3 level is highly correlated with the relapse-free survival of breast cancer patients. Here, we investigated the role of NR2E3 in benzo(a)pyrene (BaP)-mediated cell injury. BaP treatment reduced NR2E3 homo-dimer formation and expression and subsequently decreased ER expression. The chromatin immunoprecipitation assay results showed that the treatment of MCF-7 breast cancer cells and the mouse liver with BaP released NR2E3 from the ER promoter to transform the transcriptionally active histone modification status into a repressive state. NR2E3 depletion in MCF-7 cells also induced a similar inactive epigenetic status in the ER promoter region, indicating that NR2E3 is an essential epigenetic player that maintains basal ER expression. Interestingly, these negative effects of BaP on the expression levels of NR2E3 and ER were rescued by antioxidant treatment. Collectively, our study provides novel evidence to show that BaP-induced oxidative stress decreases ER expression, in part by regulating NR2E3 function, which modulates the epigenetic status of the ER promoter. NR2E3 is likely an essential epigenetic player that maintains basal ER expression to protect cells from BaP-induced oxidative injury.
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Affiliation(s)
- Tilak Khanal
- Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA
| | - Dasom Kim
- Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA
| | - Abby Johnson
- Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA
| | - Divaker Choubey
- Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA
| | - Kyounghyun Kim
- Department of Environmental Health, University of Cincinnati, College of Medicine, 160 Panzeca way, Cincinnati, OH 45267, USA.
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25
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Xu X, Xu X, Liu P, Zhu ZY, Chen J, Fu HA, Chen LL, Hu LH, Shen X. Structural Basis for Small Molecule NDB (N-Benzyl-N-(3-(tert-butyl)-4-hydroxyphenyl)-2,6-dichloro-4-(dimethylamino) Benzamide) as a Selective Antagonist of Farnesoid X Receptor α (FXRα) in Stabilizing the Homodimerization of the Receptor. J Biol Chem 2015; 290:19888-99. [PMID: 26100621 DOI: 10.1074/jbc.m114.630475] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Indexed: 01/27/2023] Open
Abstract
Farnesoid X receptor α (FXRα) as a bile acid sensor plays potent roles in multiple metabolic processes, and its antagonist has recently revealed special interests in the treatment of metabolic disorders, although the underlying mechanisms still remain unclear. Here, we identified that the small molecule N-benzyl-N-(3-(tert-butyl)-4-hydroxyphenyl)-2,6-dichloro-4-(dimethylamino) benzamide (NDB) functioned as a selective antagonist of human FXRα (hFXRα), and the crystal structure of hFXRα ligand binding domain (hFXRα-LBD) in complex with NDB was analyzed. It was unexpectedly discovered that NDB induced rearrangements of helix 11 (H11) and helix 12 (H12, AF-2) by forming a homodimer of hFXRα-LBD, totally different from the active conformation in monomer state, and the binding details were further supported by the mutation analysis. Moreover, functional studies demonstrated that NDB effectively antagonized the GW4064-stimulated FXR/RXR interaction and FXRα target gene expression in primary mouse hepatocytes, including the small heterodimer partner (SHP) and bile-salt export pump (BSEP); meanwhile, administration of NDB to db/db mice efficiently decreased the gene expressions of phosphoenolpyruvate carboxykinase (PEPCK), glucose 6-phosphatase (G6-pase), small heterodimer partner, and BSEP. It is expected that our first analyzed crystal structure of hFXRα-LBD·NDB will help expound the antagonistic mechanism of the receptor, and NDB may find its potential as a lead compound in anti-diabetes research.
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Affiliation(s)
- Xing Xu
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China, Shanghai Key Laboratory for Bone and Joint Diseases, Shanghai Institute of Traumatology and Orthopaedics, Shanghai Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China
| | - Xin Xu
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Peng Liu
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Zhi-yuan Zhu
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Jing Chen
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Hai-an Fu
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Li-li Chen
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China,
| | - Li-hong Hu
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China,
| | - Xu Shen
- From the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China,
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26
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von Alpen D, Tran HV, Guex N, Venturini G, Munier FL, Schorderet DF, Haider NB, Escher P. Differential dimerization of variants linked to enhanced S-cone sensitivity syndrome (ESCS) located in the NR2E3 ligand-binding domain. Hum Mutat 2015; 36:599-610. [PMID: 25703721 DOI: 10.1002/humu.22775] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 02/10/2015] [Indexed: 11/11/2022]
Abstract
NR2E3 encodes the photoreceptor-specific nuclear hormone receptor that acts as a repressor of cone-specific gene expression in rod photoreceptors, and as an activator of several rod-specific genes. Recessive variants located in the ligand-binding domain (LBD) of NR2E3 cause enhanced short wavelength sensitive- (S-) cone syndrome (ESCS), a retinal degeneration characterized by an excess of S-cones and non-functional rods. We analyzed the dimerization properties of NR2E3 and the effect of disease-causing LBD missense variants by bioluminescence resonance energy transfer (BRET(2) ) protein interaction assays. Homodimerization was not affected in presence of p.A256V, p.R039G, p.R311Q, and p.R334G variants, but abolished in presence of p.L263P, p.L336P, p.L353V, p.R385P, and p.M407K variants. Homology modeling predicted structural changes induced by NR2E3 LBD variants. NR2E3 LBD variants did not affect interaction with CRX, but with NRL and rev-erbα/NR1D1. CRX and NRL heterodimerized more efficiently together, than did either with NR2E3. NR2E3 did not heterodimerize with TLX/NR2E1 and RXRα/NR2C1. The identification of a new compound heterozygous patient with detectable rod function, who expressed solely the p.A256V variant protein, suggests a correlation between LBD variants able to form functional NR2E3 dimers and atypical mild forms of ESCS with residual rod function.
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Affiliation(s)
- Désirée von Alpen
- IRO-Institute for Research in Ophthalmology, Sion, Switzerland.,EPFL-Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Hoai Viet Tran
- Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Guex
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | | | - Francis L Munier
- Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
| | - Daniel F Schorderet
- IRO-Institute for Research in Ophthalmology, Sion, Switzerland.,EPFL-Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
| | - Neena B Haider
- Department of Ophthalmology, Harvard Medical School, Schepens Eye Research Institute, Boston, Massachusetts
| | - Pascal Escher
- IRO-Institute for Research in Ophthalmology, Sion, Switzerland.,Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
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27
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Zhi X, Zhou XE, He Y, Searose-Xu K, Zhang CL, Tsai CC, Melcher K, Xu HE. Structural basis for corepressor assembly by the orphan nuclear receptor TLX. Genes Dev 2015; 29:440-50. [PMID: 25691470 PMCID: PMC4335298 DOI: 10.1101/gad.254904.114] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The orphan nuclear receptor TLX regulates neural stem cell self-renewal in the adult brain and functions primarily as a transcription repressor through recruitment of Atrophin corepressors, which bind to TLX via a conserved peptide motif termed the Atro box. Zhi et al. report crystal structures of the human and insect TLX ligand-binding domain in complex with Atro box peptides. Mutations that weaken the TLX–Atrophin interaction compromise the repressive activity of TLX. In addition, mutations of corresponding residues in other members of this class of receptors diminish their repressor activities. The orphan nuclear receptor TLX regulates neural stem cell self-renewal in the adult brain and functions primarily as a transcription repressor through recruitment of Atrophin corepressors, which bind to TLX via a conserved peptide motif termed the Atro box. Here we report crystal structures of the human and insect TLX ligand-binding domain in complex with Atro box peptides. In these structures, TLX adopts an autorepressed conformation in which its helix H12 occupies the coactivator-binding groove. Unexpectedly, H12 in this autorepressed conformation forms a novel binding pocket with residues from helix H3 that accommodates a short helix formed by the conserved ALXXLXXY motif of the Atro box. Mutations that weaken the TLX–Atrophin interaction compromise the repressive activity of TLX, demonstrating that this interaction is required for Atrophin to confer repressor activity to TLX. Moreover, the autorepressed conformation is conserved in the repressor class of orphan nuclear receptors, and mutations of corresponding residues in other members of this class of receptors diminish their repressor activities. Together, our results establish the functional conservation of the autorepressed conformation and define a key sequence motif in the Atro box that is essential for TLX-mediated repression.
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Affiliation(s)
- Xiaoyong Zhi
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA; Autophagy Research Center,
| | - X Edward Zhou
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
| | - Yuanzheng He
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
| | - Kelvin Searose-Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
| | - Chun-Li Zhang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Texas 75390, USA
| | - Chih-Cheng Tsai
- Department of Cell Biology and Neuroscience, University of California at Riverside, Riverside, California 92521, USA
| | - Karsten Melcher
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
| | - H Eric Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA; Van Andel Research Institute-Shanghai Institute of Materia Medica (VARI/SIMM) Center, Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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28
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Gallastegui N, Mackinnon JAG, Fletterick RJ, Estébanez-Perpiñá E. Advances in our structural understanding of orphan nuclear receptors. Trends Biochem Sci 2014; 40:25-35. [PMID: 25499868 DOI: 10.1016/j.tibs.2014.11.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 10/31/2014] [Accepted: 11/03/2014] [Indexed: 12/24/2022]
Abstract
Nuclear receptors (NRs) are key players in the regulation of gene expression, coordinating protein assemblies upon their surfaces. NRs are regulated by ligand binding, which remodels the interaction surfaces and subsequently influences macromolecular complex formation. Structural biology has been instrumental in the discovery of some of these ligands, but there are still orphan NRs (ONRs) whose bona fide ligands have yet to be identified. Over the past decade, fundamental structural and functional breakthroughs have led to a deeper understanding of ONR actions and their multidomain organization. Here, we summarize the structural advances in ONRs with implications for the therapeutic treatment of diseases such as metabolic syndrome and cancer.
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Affiliation(s)
- Nerea Gallastegui
- The Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biology, University of Barcelona (UB), Baldiri Reixac 15-21, 08028 Barcelona, Spain
| | - Jonathan A G Mackinnon
- The Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biology, University of Barcelona (UB), Baldiri Reixac 15-21, 08028 Barcelona, Spain
| | - Robert J Fletterick
- The Department of Biochemistry and Biophysics, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Eva Estébanez-Perpiñá
- The Institute of Biomedicine of the University of Barcelona (IBUB), Department of Biochemistry and Molecular Biology, University of Barcelona (UB), Baldiri Reixac 15-21, 08028 Barcelona, Spain.
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29
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The human orphan nuclear receptor tailless (TLX, NR2E1) is druggable. PLoS One 2014; 9:e99440. [PMID: 24936658 PMCID: PMC4060991 DOI: 10.1371/journal.pone.0099440] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 05/14/2014] [Indexed: 12/31/2022] Open
Abstract
Nuclear receptors (NRs) are an important group of ligand-dependent transcriptional factors. Presently, no natural or synthetic ligand has been identified for a large group of orphan NRs. Small molecules to target these orphan NRs will provide unique resources for uncovering regulatory systems that impact human health and to modulate these pathways with drugs. The orphan NR tailless (TLX, NR2E1), a transcriptional repressor, is a major player in neurogenesis and Neural Stem Cell (NSC) derived brain tumors. No chemical probes that modulate TLX activity are available, and it is not clear whether TLX is druggable. To assess TLX ligand binding capacity, we created homology models of the TLX ligand binding domain (LBD). Results suggest that TLX belongs to an emerging class of NRs that lack LBD helices α1 and α2 and that it has potential to form a large open ligand binding pocket (LBP). Using a medium throughput screening strategy, we investigated direct binding of 20,000 compounds to purified human TLX protein and verified interactions with a secondary (orthogonal) assay. We then assessed effects of verified binders on TLX activity using luciferase assays. As a result, we report identification of three compounds (ccrp1, ccrp2 and ccrp3) that bind to recombinant TLX protein with affinities in the high nanomolar to low micromolar range and enhance TLX transcriptional repressive activity. We conclude that TLX is druggable and propose that our lead compounds could serve as scaffolds to derive more potent ligands. While our ligands potentiate TLX repressive activity, the question of whether it is possible to develop ligands to de-repress TLX activity remains open.
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30
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IL-13Rα2 mediates PNR-induced migration and metastasis in ERα-negative breast cancer. Oncogene 2014; 34:1596-607. [PMID: 24747967 DOI: 10.1038/onc.2014.53] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/30/2014] [Accepted: 02/11/2014] [Indexed: 12/21/2022]
Abstract
Emerging evidence has linked photoreceptor cell-specific nuclear receptor (PNR/NR2E3), an orphan nuclear hormone receptor, to human breast cancer. PNR was shown to be a transcriptional activator of estrogen receptor-α (ERα) in ERα-positive breast cancer cell lines and high-level expression of PNR correlates with favorable response of ERα-positive breast cancer patients to tamoxifen. Interestingly, gene expression microarray study shows that PNR regulates distinct genes from those regulated by ERα, suggesting that PNR could have ERα-independent functions. Herein, we investigated the function of PNR in ERα-negative breast cancer cells. Our results showed that PNR-induced cell migration and metastasis of ERα-negative breast cancer cells both in vitro and in vivo, and the effect was attributed to the upregulation of interleukin (IL)-13Rα2, a high-affinity receptor for IL-13 that regulates tumor growth, invasion and metastasis of various human cancers. Mechanistically, PNR activated transcription of IL-13Rα2 through direct recruitment to IL-13Rα2 promoter. Upon stimulation with IL-13, IL-13Rα2 increased the extracellular signal-regulated kinases 1 and 2 phosphorylation, which led to breast cancer migration and metastasis. The IL-13 triggered signal cascade was specific to IL-13Rα2, as the closely related IL-13Rα1 was not regulated by PNR. IL-13Rα2 is a novel tumor antigen that is overexpressed in a variety of solid tumor types. This study presents the first evidence that PNR could promote ERα-negative breast cancer metastasis through activation of IL-13Rα2-mediated signaling pathway.
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31
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Structural insights into gene repression by the orphan nuclear receptor SHP. Proc Natl Acad Sci U S A 2013; 111:839-44. [PMID: 24379397 DOI: 10.1073/pnas.1322827111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Small heterodimer partner (SHP) is an orphan nuclear receptor that functions as a transcriptional repressor to regulate bile acid and cholesterol homeostasis. Although the precise mechanism whereby SHP represses transcription is not known, E1A-like inhibitor of differentiation (EID1) was isolated as a SHP-interacting protein and implicated in SHP repression. Here we present the crystal structure of SHP in complex with EID1, which reveals an unexpected EID1-binding site on SHP. Unlike the classical cofactor-binding site near the C-terminal helix H12, the EID1-binding site is located at the N terminus of the receptor, where EID1 mimics helix H1 of the nuclear receptor ligand-binding domain. The residues composing the SHP-EID1 interface are highly conserved. Their mutation diminishes SHP-EID1 interactions and affects SHP repressor activity. Together, these results provide important structural insights into SHP cofactor recruitment and repressor function and reveal a conserved protein interface that is likely to have broad implications for transcriptional repression by orphan nuclear receptors.
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