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Rahunen R, Tulppo M, Rinne V, Lepojärvi S, Perkiömäki JS, Huikuri HV, Ukkola O, Junttila J, Hukkanen J. Liver X Receptor Agonist 4β-Hydroxycholesterol as a Prognostic Factor in Coronary Artery Disease. J Am Heart Assoc 2024; 13:e031824. [PMID: 38390795 PMCID: PMC10944077 DOI: 10.1161/jaha.123.031824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 01/05/2024] [Indexed: 02/24/2024]
Abstract
BACKGROUND Regardless of progress in treatment of coronary artery disease (CAD), there is still a significant residual risk of death in patients with CAD, highlighting the need for additional risk stratification markers. Our previous study provided evidence for a novel blood pressure-regulating mechanism involving 4β-hydroxycholesterol (4βHC), an agonist for liver X receptors, as a hypotensive factor. The aim was to determine the role of 4βHC as a prognostic factor in CAD. METHODS AND RESULTS The ARTEMIS (Innovation to Reduce Cardiovascular Complications of Diabetes at the Intersection) cohort consists of 1946 patients with CAD. Men and women were analyzed separately in quartiles according to plasma 4βHC. Basic characteristics, medications, ECG, and echocardiography parameters as well as mortality rate were analyzed. At baseline, subjects with a beneficial cardiovascular profile, as assessed with traditional markers such as body mass index, exercise capacity, prevalence of diabetes, and use of antihypertensives, had the highest plasma 4βHC concentrations. However, in men, high plasma 4βHC was associated with all-cause death, cardiac death, and especially sudden cardiac death (SCD) in a median follow-up of 8.8 years. Univariate and comprehensively adjusted hazard ratios for SCD in the highest quartile were 3.76 (95% CI, 1.6-8.7; P=0.002) and 4.18 (95% CI, 1.5-11.4; P=0.005), respectively. In contrast, the association of cardiac death and SCD in women showed the lowest risk in the highest 4βHC quartile. CONCLUSIONS High plasma 4βHC concentration was associated with death and especially SCD in men, while an inverse association was detected in women. Our results suggest 4βHC as a novel sex-specific risk marker of cardiac death and especially SCD in chronic CAD. REGISTRATION INFORMATION clinicaltrials.gov. Identifier NCT01426685.
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Affiliation(s)
- Roosa Rahunen
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Biocenter OuluUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | - Mikko Tulppo
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | | | - Samuli Lepojärvi
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | - Juha S. Perkiömäki
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | - Heikki V. Huikuri
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | - Olavi Ukkola
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | - Juhani Junttila
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Biocenter OuluUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
| | - Janne Hukkanen
- Research Unit of Biomedicine and Internal MedicineUniversity of OuluOuluFinland
- Biocenter OuluUniversity of OuluOuluFinland
- Medical Research Center OuluOulu University Hospital and University of OuluOuluFinland
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Gustafsson JÅ, Li XC, Suh JH, Lou X. A structural perspective of liver X receptors. VITAMINS AND HORMONES 2023; 123:231-247. [PMID: 37717986 DOI: 10.1016/bs.vh.2023.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Liver X receptors α and β are members of the nuclear receptor family, which comprise a flexible N-terminal domain, a DNA binding domain, a hinge linker, and a ligand binding domain. Liver X receptors are important regulators of cholesterol and lipid homeostasis by controlling the transcription of numerous genes. Key to their transcriptional role is synergetic interaction among the domains. DNA binding domain binds on DNA; ligand binding domain is a crucial switch to control the transcription activity through conformational change caused by ligand binding. The Liver X receptors form heterodimers with retinoid X receptor and then the liganded heterodimer may recruit other necessary transcription components to form an active transcription complex.
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Affiliation(s)
- Jan-Åke Gustafsson
- Department of Cell Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States; Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.
| | - Xian Chang Li
- Immunobiology and Transplant Science Center and Department of Surgery, Houston Methodist Research Institute, Houston, TX, United States; Department of Surgery, Weill Cornell Medical College of Cornell University, New York, NY, United States
| | - Ji Ho Suh
- Department of Anesthesiology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Xiaohua Lou
- Immunobiology and Transplant Science Center and Department of Surgery, Houston Methodist Research Institute, Houston, TX, United States.
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Identification and characterization of alternative splicing variants of buffalo LXRα expressed in mammary gland. Sci Rep 2022; 12:10588. [PMID: 35732883 PMCID: PMC9218113 DOI: 10.1038/s41598-022-14771-0] [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: 02/01/2022] [Accepted: 06/13/2022] [Indexed: 11/09/2022] Open
Abstract
Liver X receptor α (LXRα) is a ligand-dependent transcription factor and plays an important role in the regulation of cholesterol homeostasis, fatty acid biosynthesis and glucose metabolism. In this study, transcripts of LXRα gene were cloned and characterized from buffalo mammary gland, and three alternative splicing transcripts of buffalo LXRα gene were identified, named LXRα1, LXRα2 and LXRα3. The structure of the LXRα transcripts of buffalo and cattle was highly similar. Bioinformatics analysis showed that LXRα1 contains two complete functional domains of LXRα, one is the DNA-binding domain (NR_DBD_LXR) and the other is the ligand-binding domain (NR_LBD_LXR). The reading frame of LXRα2 is altered due to the skipping of exon 9, which truncates its encoding protein prematurely at the 400th amino acid residue, making it contain a complete DNA-binding domain and part of a ligand-binding domain. Due to the deletion of exon 4, the protein encoded by LXRα3 lacks 89 amino acid residues and contains only a complete ligand-binding domain, which makes it lose its transcriptional regulation function. In addition, motifs and conserved domains of three LXRα variants of buffalo were highly consistent with those of corresponding transcripts from other mammal species. Subcellular localization analysis showed that LXRα1 plays a functional role in the nucleus of buffalo mammary epithelial cells, while LXRα2 and LXRα3 are distributed in the nucleus and cytoplasm. Compared with non-lactating period, the mRNA abundance of the three LXRα transcripts in the mammary gland tissue of buffalo increased during lactating period, revealing that they play a key role in the synthesis of buffalo milk fat. Among the three LXRα transcripts, LXRα1 has the highest expression in the mammary gland, indicating that it is the major transcript in the mammary gland and has important regulatory functions, while LXRα2 and LXRα3 may have regulatory effects on the function of LXRα1. This study highlights the key role of LXRα alternative splicing in the post-transcriptional regulation of buffalo lactation.
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Wang Y, Li GL, Qi YL, Li LY, Wang LF, Wang CR, Niu XR, Liu TX, Wang J, Yang GY, Zeng L, Chu BB. Pseudorabies Virus Inhibits Expression of Liver X Receptors to Assist Viral Infection. Viruses 2022; 14:v14030514. [PMID: 35336921 PMCID: PMC8954865 DOI: 10.3390/v14030514] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 12/16/2022] Open
Abstract
Pseudorabies virus (PRV) is a contagious herpesvirus that causes Aujeszky’s disease and economic losses worldwide. Liver X receptors (LXRs) belong to the nuclear receptor superfamily and are critical for the control of lipid homeostasis. However, the role of LXR in PRV infection has not been fully established. In this study, we found that PRV infection downregulated the mRNA and protein levels of LXRα and LXRβ in vitro and in vivo. Furthermore, we discovered that LXR activation suppressed PRV proliferation, while LXR inhibition promoted PRV proliferation. We demonstrated that LXR activation-mediated reduction of cellular cholesterol was critical for the dynamics of PRV entry-dependent clathrin-coated pits. Replenishment of cholesterol restored the dynamics of clathrin-coated pits and PRV entry under LXR activation conditions. Interestingly, T0901317, an LXR agonist, prevented PRV infection in mice. Our results support a model that PRV modulates LXR-regulated cholesterol metabolism to facilitate viral proliferation.
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Affiliation(s)
- Yi Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Guo-Li Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Yan-Li Qi
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Li-Yun Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Lu-Fang Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Cong-Rong Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Xin-Rui Niu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Tao-Xue Liu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Jiang Wang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
| | - Guo-Yu Yang
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
- International Joint Research Center of National Animal Immunology, Henan Agricultural University, Zhengzhou 450046, China
- College of Animal Science & Technology, Henan University of Animal Husbandry and Economy, Zhengzhou 450047, China
| | - Lei Zeng
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
- Correspondence: (L.Z.); (B.-B.C.)
| | - Bei-Bei Chu
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, China; (Y.W.); (G.-L.L.); (Y.-L.Q.); (L.-Y.L.); (L.-F.W.); (C.-R.W.); (X.-R.N.); (T.-X.L.); (J.W.)
- Key Laboratory of Animal Biochemistry and Nutrition, Ministry of Agriculture and Rural Affairs of the People’s Republic of China, Zhengzhou 450046, China;
- Key Laboratory of Animal Growth and Development, Zhengzhou 450046, China
- International Joint Research Center of National Animal Immunology, Henan Agricultural University, Zhengzhou 450046, China
- Correspondence: (L.Z.); (B.-B.C.)
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Collins JM, Lu R, Wang X, Zhu HJ, Wang D. Transcriptional Regulation of Carboxylesterase 1 in Human Liver: Role of the Nuclear Receptor Subfamily 1 Group H Member 3 and Its Splice Isoforms. Drug Metab Dispos 2022; 50:43-48. [PMID: 34697082 PMCID: PMC8969197 DOI: 10.1124/dmd.121.000649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/20/2021] [Indexed: 01/03/2023] Open
Abstract
Carboxylesterase 1 (CES1) is the predominant carboxylesterase in the human liver, involved in metabolism of both xenobiotics and endogenous substrates. Genetic or epigenetic factors that alter CES1 activity or expression are associated with changes in drug response, lipid, and glucose homeostasis. However, the transcriptional regulation of CES1 in the human liver remains uncertain. By applying both the random forest and Sobol's Sensitivity Indices (SSI) to analyze existing liver RNA expression microarray data (GSE9588), we identified nuclear receptor subfamily 1 group H member 3 (NR1H3) liver X receptor (LXR)α as a key factor regulating constitutive CES1 expression. This model prediction was validated using small interfering RNA (siRNA) knockdown and CRISPR-mediated transcriptional activation of NR1H3 in Huh7 and HepG2 cells. We found that NR1H3's activation of CES1 is splice isoform-specific, namely that increased expression of the NR1H3-211 isoform increased CES1 expression whereas NR1H3-201 did not. Also, in human liver samples, expression of NR1H3-211 and CES1 are correlated, whereas NR1H3-201 and CES1 are not. This trend also occurs during differentiation of induced pluripotent stem cells (iPSCs) to hepatocytes, where only expression of the NR1H3-211 isoform parallels expression of CES1 Moreover, we found that treatment with the NR1H3 agonist T0901317 in HepG2 cells had no effect on CES1 expression. Overall, our results demonstrate a key role of NR1H3 in maintaining the constitutive expression of CES1 in the human liver. Furthermore, our results support that the effect of NR1H3 is splice isoform-specific and appears to be ligand independent. SIGNIFICANCE STATEMENT: Despite the central role of carboxylesterase 1 (CES1) in metabolism of numerous medications, little is known about its transcriptional regulation. This study identifies nuclear receptor subfamily 1 group H member 3 as a key regulator of constitutive CES1 expression and therefore is a potential target for future studies to understand interperson variabilities in CES1 activity and drug metabolism.
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Affiliation(s)
- Joseph M Collins
- Department of Pharmacotherapy and Translational Research, Center for Pharmacogenomics, College of Pharmacy, University of Florida, Gainesville, Florida (J.M.C., D.W.); The Quantitative Sciences Unit, Division of Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, California (R.L.); Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, (X.W.); and Department of Clinical Pharmacy, University of Michigan, Ann Arbor, Michigan (H.-J.Z.)
| | - Rong Lu
- Department of Pharmacotherapy and Translational Research, Center for Pharmacogenomics, College of Pharmacy, University of Florida, Gainesville, Florida (J.M.C., D.W.); The Quantitative Sciences Unit, Division of Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, California (R.L.); Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, (X.W.); and Department of Clinical Pharmacy, University of Michigan, Ann Arbor, Michigan (H.-J.Z.)
| | - Xinwen Wang
- Department of Pharmacotherapy and Translational Research, Center for Pharmacogenomics, College of Pharmacy, University of Florida, Gainesville, Florida (J.M.C., D.W.); The Quantitative Sciences Unit, Division of Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, California (R.L.); Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, (X.W.); and Department of Clinical Pharmacy, University of Michigan, Ann Arbor, Michigan (H.-J.Z.)
| | - Hao-Jie Zhu
- Department of Pharmacotherapy and Translational Research, Center for Pharmacogenomics, College of Pharmacy, University of Florida, Gainesville, Florida (J.M.C., D.W.); The Quantitative Sciences Unit, Division of Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, California (R.L.); Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, (X.W.); and Department of Clinical Pharmacy, University of Michigan, Ann Arbor, Michigan (H.-J.Z.)
| | - Danxin Wang
- Department of Pharmacotherapy and Translational Research, Center for Pharmacogenomics, College of Pharmacy, University of Florida, Gainesville, Florida (J.M.C., D.W.); The Quantitative Sciences Unit, Division of Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, California (R.L.); Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, (X.W.); and Department of Clinical Pharmacy, University of Michigan, Ann Arbor, Michigan (H.-J.Z.)
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Thorne JL, Cioccoloni G. Nuclear Receptors and Lipid Sensing. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1390:83-105. [DOI: 10.1007/978-3-031-11836-4_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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7
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Lianto P, Hutchinson SA, Moore JB, Hughes TA, Thorne JL. Characterization and prognostic value of LXR splice variants in triple-negative breast cancer. iScience 2021; 24:103212. [PMID: 34755086 PMCID: PMC8560626 DOI: 10.1016/j.isci.2021.103212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/11/2021] [Accepted: 09/29/2021] [Indexed: 01/17/2023] Open
Abstract
Activity of liver x receptor (LXR), the homeostatic regulator of cholesterol metabolism, is elevated in triple-negative breast cancer (BCa) relative to other BCa subtypes, driving drug resistance and metastatic gene signatures. The loci encoding LXRα and LXRβ produce multiple alternatively spliced proteins, but the true range of variants and their relevance to cancer remain poorly defined. Here, we report seven LXR splice variants, three of which have not previously been reported and five that were prognostic for disease-free survival. Expression of full-length LXRα splice variants was associated with poor prognosis, consistent with a role as an oncogenic driver of triple-negative tumor pathophysiology. Contrary to this was the observation that high expression of truncated LXRα splice variants or any LXRβ splice variant was associated with longer survival. These findings indicate that LXR isoform abundance is an important aspect of understanding the link between dysregulated cholesterol metabolism and cancer pathophysiology.
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Affiliation(s)
- Priscilia Lianto
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
| | | | - J. Bernadette Moore
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
| | | | - James L. Thorne
- School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK
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Mukha A, Kalkhoven E, van Mil SWC. Splice variants of metabolic nuclear receptors: Relevance for metabolic disease and therapeutic targeting. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166183. [PMID: 34058349 DOI: 10.1016/j.bbadis.2021.166183] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 12/13/2022]
Abstract
Metabolic nuclear receptors are ligand-activated transcription factors which control a wide range of metabolic processes and signaling pathways in response to nutrients and xenobiotics. Targeting these NRs is at the forefront of our endeavours to generate novel treatment options for diabetes, metabolic syndrome and fatty liver disease. Numerous splice variants have been described for these metabolic receptors. Structural changes, as a result of alternative splicing, lead to functional differences among NR isoforms, resulting in the regulation of different metabolic pathways by these NR splice variants. In this review, we describe known splice variants of FXR, LXRs, PXR, RXR, LRH-1, CAR and PPARs. We discuss their structure and functions, and elaborate on the regulation of splice variant abundance by nutritional signals. We conclude that NR splice variants pose an intriguing new layer of complexity in metabolic signaling, which needs to be taken into account in the development of treatment strategies for metabolic diseases.
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Affiliation(s)
- Anna Mukha
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Eric Kalkhoven
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Saskia W C van Mil
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands.
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Shehata WA, Maraee A, Mehesin M, Tayel N, Azmy R. Genetic polymorphism of liver X receptor gene in vitiligo: Does it have an association? J Cosmet Dermatol 2020; 20:1906-1914. [PMID: 33031595 DOI: 10.1111/jocd.13772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/01/2022]
Abstract
BACKGROUND Vitiligo is an acquired depigmentation of the skin and the mucous membranes, exhibited as white macules and patches due to selective loss of melanocytes. Etiological theories of vitiligo include genetic, immunological, neurohormonal, cytotoxic, biochemical, oxidative stress, and newer theories of melanocytorrhagy and diminished melanocytes survival. It has been revealed that liver X receptor alpha gene is expressed in skin tissue such as sebaceous glands, hair follicle, keratinocytes, and fibroblasts and is linked to various skin disorders as acne vulgaris and psoriasis. AIM OF THE STUDY To evaluate the association between liver X receptor-α gene polymorphism (rs11039155 and rs2279238) and vitiligo and whether they are related to disease activity and severity or not. SUBJECTS AND METHODS 50 vitiligo patients and 20 age- and sex-matched apparently healthy controls were enrolled. All the included subjects were genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis technique for (-6G/A) and (+1257C/T) SNPs. RESULTS Significant statistical difference between cases and controls regarding genotype and allele frequencies for -6G/A polymorphism with predominance of AA genotype (OR: 5.1, 95% CI: 1.6-15.9) and A allele (OR: 5.3, 95% CI: 1.6-15.9) in cases and also for +1257C/T polymorphism with predominance of TT genotype OR: 9.2 (95% CI: 1.4-82.9) and T allele OR: 3.4 (95% CI: 1.4-8.1) in vitiligo cases. No significant relationship between -6G/A genotypes nor +1257C/T genotypes and disease activity and severity. CONCLUSION The study showed significant association between Liver X receptor gene polymorphisms (-6G/A, +1257 C/T) and development of vitiligo in Egyptian patients. However, it failed to show any relation with disease activity nor severity.
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Affiliation(s)
- Wafaa A Shehata
- Dermatology, Andrology and STDs Department, Menoufia University, Shebin El-Kom, Egypt
| | - Alaa Maraee
- Dermatology, Andrology and STDs Department, Menoufia University, Shebin El-Kom, Egypt
| | - Marwa Mehesin
- General Practitioner in Health Sector, Shebin El-Kom, Egypt
| | - Nermin Tayel
- Lecturer of Molecular Diagnostics & Therapeutics, Molecular Diagnostics & Therapeutics Department, Genetic Engineering and Biotechnology Research Institute, Sadat City University, Sadat, Egypt
| | - Rania Azmy
- Medical Biochemistry and Molecular Biology Department, Menoufia University, Shebin El-Kom, Egypt
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Ramón-Vázquez A, de la Rosa JV, Tabraue C, Lopez F, Díaz-Chico BN, Bosca L, Tontonoz P, Alemany S, Castrillo A. Common and Differential Transcriptional Actions of Nuclear Receptors Liver X Receptors α and β in Macrophages. Mol Cell Biol 2019; 39:e00376-18. [PMID: 30602495 PMCID: PMC6379585 DOI: 10.1128/mcb.00376-18] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 08/29/2018] [Accepted: 12/07/2018] [Indexed: 02/07/2023] Open
Abstract
The liver X receptors α and β (LXRα and LXRβ) are oxysterol-activated transcription factors that coordinately regulate gene expression that is important for cholesterol and fatty acid metabolism. In addition to their roles in lipid metabolism, LXRs participate in the transcriptional regulation of macrophage activation and are considered potent regulators of inflammation. LXRs are highly similar, and despite notable exceptions, most of their reported functions are substantially overlapping. However, their individual genomic distribution and transcriptional capacities have not been characterized. Here, we report a macrophage cellular model expressing equivalent levels of tagged LXRs. Analysis of data from chromatin immunoprecipitation coupled with deep sequencing revealed that LXRα and LXRβ occupy both overlapping and exclusive genomic regulatory sites of target genes and also control the transcription of a receptor-exclusive set of genes. Analysis of genomic H3K27 acetylation and mRNA transcriptional changes in response to synthetic agonist or antagonist treatments revealed a putative mode of pharmacologically independent regulation of transcription. Integration of microarray and sequencing data enabled the description of three possible mechanisms of LXR transcriptional activation. Together, these results contribute to our understanding of the common and differential genomic actions of LXRs and their impact on biological processes in macrophages.
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Affiliation(s)
- Ana Ramón-Vázquez
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid, Madrid, Spain
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Juan Vladimir de la Rosa
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid, Madrid, Spain
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Carlos Tabraue
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Felix Lopez
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Bonifacio Nicolas Díaz-Chico
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Lisardo Bosca
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid, Madrid, Spain
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Susana Alemany
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid, Madrid, Spain
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Antonio Castrillo
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid, Madrid, Spain
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Grupo de Investigación Medio Ambiente y Salud, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
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11
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Hu X, Zhang N, Fu Y. Role of Liver X Receptor in Mastitis Therapy and Regulation of Milk Fat Synthesis. J Mammary Gland Biol Neoplasia 2019; 24:73-83. [PMID: 30066175 DOI: 10.1007/s10911-018-9403-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 07/04/2018] [Indexed: 02/03/2023] Open
Abstract
Mastitis is important disease that causes huge economic losses in the dairy industry. In recent years, antibiotic therapy has become the primary treatment for mastitis, however, due to drug residue in milk and food safety factors, we lack safe and effective drugs for treating mastitis. Therefore, new targets and drugs are urgently needed to control mastitis. LXRα, one of the main members of the nuclear receptor superfamily, is reported to play important roles in metabolism, infection and immunity. Activation of LXRα could inhibit LPS-induced mastitis. Furthermore, LXRα is reported to enhance milk fat production, thus, LXRα may serve as a new target for mastitis therapy and regulation of milk fat synthesis. This review summarizes the effects of LXRα in regulating milk fat synthesis and treatment of mastitis and highlights the potential agonists involved in both issues.
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MESH Headings
- Animals
- Anti-Inflammatory Agents/pharmacology
- Anti-Inflammatory Agents/therapeutic use
- Cattle
- Dairying
- Escherichia coli/isolation & purification
- Escherichia coli/pathogenicity
- Female
- Global Burden of Disease
- Humans
- Immunity, Innate
- Lactation/metabolism
- Lipid Metabolism
- Liver X Receptors/agonists
- Liver X Receptors/metabolism
- Mammary Glands, Animal/cytology
- Mammary Glands, Animal/metabolism
- Mammary Glands, Animal/microbiology
- Mammary Glands, Animal/pathology
- Mammary Glands, Human/cytology
- Mammary Glands, Human/immunology
- Mammary Glands, Human/microbiology
- Mammary Glands, Human/pathology
- Mastitis/drug therapy
- Mastitis/immunology
- Mastitis/microbiology
- Mastitis, Bovine/drug therapy
- Mastitis, Bovine/epidemiology
- Mastitis, Bovine/immunology
- Mastitis, Bovine/microbiology
- Membrane Microdomains/metabolism
- Milk/metabolism
- Prevalence
- Receptors, Pattern Recognition/metabolism
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Affiliation(s)
- Xiaoyu Hu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province, 130062, People's Republic of China
| | - Naisheng Zhang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province, 130062, People's Republic of China.
| | - Yunhe Fu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province, 130062, People's Republic of China.
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12
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Saadane A, Mast N, Trichonas G, Chakraborty D, Hammer S, Busik JV, Grant MB, Pikuleva IA. Retinal Vascular Abnormalities and Microglia Activation in Mice with Deficiency in Cytochrome P450 46A1-Mediated Cholesterol Removal. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 189:405-425. [PMID: 30448403 DOI: 10.1016/j.ajpath.2018.10.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/27/2018] [Accepted: 10/15/2018] [Indexed: 12/11/2022]
Abstract
CYP46A1 is the cytochrome P450 enzyme that converts cholesterol to 24-hydroxycholesterol, a cholesterol elimination product and a potent liver X receptor (LXR) ligand. We conducted retinal characterizations of Cyp46a1-/- mice that had normal fasting blood glucose levels but up to a 1.8-fold increase in retinal cholesterol. The retina of Cyp46a1-/- mice exhibited venous beading and tortuosity, microglia/macrophage activation, and increased vascular permeability, features commonly associated with diabetic retinopathy. The expression of Lxrα and Lxrβ was increased in both the whole Cyp46a1-/- retina and retinal macroglia/macrophages. The LXR-target genes were affected as well, primarily in activated microglial cells and macrophages. In the latter, the LXR-transactivated genes (Abca1, Abcg1, Apod, Apoe, Mylip, and Arg2) were up-regulated; similarly, there was an up-regulation of the LXR-transrepressed genes (Ccl2, Ptgs2, Cxcl1, Il1b, Il6, Nos2, and Tnfa). For comparison, gene expression was investigated in bone marrow-derived macrophages from Cyp46a1-/- mice as well as retinal and bone marrow-derived macrophages from Cyp27a1-/- and Cyp27a1-/-Cyp46a1-/- mice. CYP46A1 expression was detected in retinal endothelial cells, and this expression was increased in the proinflammatory environment. Retinal Cyp46a1-/- phosphoproteome revealed altered phosphorylation of 30 different proteins, including tight junction protein zonula occludens 1 and aquaporin 4. Collectively, the data obtained establish metabolic and regulatory significance of CYP46A1 for the retina and suggest pharmacologic activation of CYP46A1 as a potential therapeutic approach to dyslipidemia-induced retinal damage.
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Affiliation(s)
- Aicha Saadane
- Department of Ophthalmology and Visual Sciences, the University Hospitals, Case Western Reserve University, Cleveland, Ohio
| | - Natalia Mast
- Department of Ophthalmology and Visual Sciences, the University Hospitals, Case Western Reserve University, Cleveland, Ohio
| | - George Trichonas
- Department of Ophthalmology and Visual Sciences, the University Hospitals, Case Western Reserve University, Cleveland, Ohio
| | | | - Sandra Hammer
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Julia V Busik
- Department of Physiology, Michigan State University, East Lansing, Michigan
| | - Maria B Grant
- Department of Ophthalmology, University of Alabama, Birmingham, Alabama
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Sciences, the University Hospitals, Case Western Reserve University, Cleveland, Ohio.
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13
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Zhang X, Carlisle SM, Doll MA, Martin RCG, States JC, Klinge CM, Hein DW. High N-Acetyltransferase 1 Expression Is Associated with Estrogen Receptor Expression in Breast Tumors, but Is not Under Direct Regulation by Estradiol, 5 α-androstane-3 β,17 β-Diol, or Dihydrotestosterone in Breast Cancer Cells. J Pharmacol Exp Ther 2018; 365:84-93. [PMID: 29339455 DOI: 10.1124/jpet.117.247031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/12/2018] [Indexed: 12/19/2022] Open
Abstract
N-acetyltransferase 1 (NAT1) is an enzyme that metabolizes carcinogens, which suggests a potential role in breast carcinogenesis. High NAT1 expression in breast tumors is associated with estrogen receptor α (ERα+) and the luminal subtype. We report that NAT1 mRNA transcript, protein, and enzyme activity were higher in human breast tumors with high expression of ERα/ESR1 compared with normal breast tissue. There was a strong correlation between NATb promoter and NAT1 protein expression/enzyme activity. High NAT1 expression in tumors was not the result of adipocytes, as evidenced by low perilipin (PLIN) expression. ESR1, NAT1, and XBP1 expression were associated in tumor biopsies. Direct regulation of NAT1 transcription by estradiol (E2) was investigated in ERα (+) MCF-7 and T47D breast cancer cells. E2 did not increase NAT1 transcript expression but increased progesterone receptor expression in a dose-dependent manner. Likewise, NAT1 transcript levels were not increased by dihydrotestosterone (DHT) or 5α-androstane-3β, (3β-adiol) 17β-diol. Dithiothreitol increased levels of the activated, spliced XBP1 in ERα (+) MCF-7 and T47D breast cancer cells but did not affect NAT1 or ESR1 expression. We conclude that NAT1 expression is not directly regulated by E2, DHT, 3β-adiol, or dithiothreitol despite high NAT1 and ESR1 expression in luminal A breast cancer cells, suggesting that ESR1, XBP1, and NAT1 expression may share a common transcriptional network arising from the luminal epithelium associated with better survival in breast cancer. Clusters of high-expression genes, including NAT1, in breast tumors might serve as potential targets for novel therapeutic drug development.
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Affiliation(s)
- Xiaoyan Zhang
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - Samantha M Carlisle
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - Mark A Doll
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - Robert C G Martin
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - J Christopher States
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - Carolyn M Klinge
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - David W Hein
- Departments of Pharmacology and Toxicology (X.Z., S.M.C., M.A.D., J.C.S., D.W.H.), Surgery (R.C.G.M.), Biochemistry and Molecular Genetics (C.M.K.), and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, Kentucky
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14
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Cannon MV, Silljé HHW, Sijbesma JWA, Vreeswijk-Baudoin I, Ciapaite J, van der Sluis B, van Deursen J, Silva GJJ, de Windt LJ, Gustafsson JÅ, van der Harst P, van Gilst WH, de Boer RA. Cardiac LXRα protects against pathological cardiac hypertrophy and dysfunction by enhancing glucose uptake and utilization. EMBO Mol Med 2016; 7:1229-43. [PMID: 26160456 PMCID: PMC4568954 DOI: 10.15252/emmm.201404669] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Pathological cardiac hypertrophy is characterized by a shift in metabolic substrate utilization from fatty acids to glucose, but the molecular events underlying the metabolic remodeling remain poorly understood. Here, we investigated the role of liver X receptors (LXRs), which are key regulators of glucose and lipid metabolism, in cardiac hypertrophic pathogenesis. Using a transgenic approach in mice, we show that overexpression of LXRα acts to protect the heart against hypertrophy, fibrosis, and dysfunction. Gene expression profiling studies revealed that genes regulating metabolic pathways were differentially expressed in hearts with elevated LXRα. Functionally, LXRα overexpression in isolated cardiomyocytes and murine hearts markedly enhanced the capacity for myocardial glucose uptake following hypertrophic stress. Conversely, this adaptive response was diminished in LXRα-deficient mice. Transcriptional changes induced by LXRα overexpression promoted energy-independent utilization of glucose via the hexosamine biosynthesis pathway, resulting in O-GlcNAc modification of GATA4 and Mef2c and the induction of cytoprotective natriuretic peptide expression. Our results identify LXRα as a key cardiac transcriptional regulator that helps orchestrate an adaptive metabolic response to chronic cardiac stress, and suggest that modulating LXRα may provide a unique opportunity for intervening in myocyte metabolism.
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Affiliation(s)
- Megan V Cannon
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Herman H W Silljé
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jürgen W A Sijbesma
- Department of Nuclear Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Inge Vreeswijk-Baudoin
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jolita Ciapaite
- Department Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Bart van der Sluis
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan van Deursen
- Department of Biochemistry & Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Gustavo J J Silva
- Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Leon J de Windt
- Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Jan-Åke Gustafsson
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA Department of Biosciences and Nutrition, Novum, Karolinska Institutet, Huddinge, Sweden
| | - Pim van der Harst
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Wiek H van Gilst
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Rudolf A de Boer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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15
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Papageorgiou AP, Heggermont W, Rienks M, Carai P, Langouche L, Verhesen W, De Boer RA, Heymans S. Liver X receptor activation enhances CVB3 viral replication during myocarditis by stimulating lipogenesis. Cardiovasc Res 2015; 107:78-88. [PMID: 25998987 DOI: 10.1093/cvr/cvv157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 05/13/2015] [Indexed: 12/16/2022] Open
Abstract
AIMS Viral myocarditis (VM) is severe cardiac inflammation that can result in sudden death or congestive heart failure in previously healthy adults, with no effective therapy. Liver X receptor (LXR) agonists have both anti-inflammatory and lipid-lowering properties. This study investigates whether LXR agonist T0901317 may modulate viral replication and cardiac inflammation during VM. METHODS AND RESULTS (i) Adult mice were administered T0901317 or vehicle with the onset of inflammation during CVB3 virus myocarditis or (ii) treated 2 days prior to CVB3 infection. Against what we expected, T0901317 treatment did not alter leucocyte infiltration after CVB3 infection; yet pre-administration with T0901317 resulted in increased mortality upon CVB3 infection, higher cardiac viral presence, and increased cardiomyocyte damage when compared with the vehicle. Furthermore, we show a correlation of fatty acid synthase (FAS) and sterol regulatory element-binding protein 1c (SREBP-1c) with CVB3 viral load in the heart and that T0901317 is able to enhance the cardiac expression of FAS and SREBP-1c. Finally, we show in vitro that T0901317 is able to exaggerate CVB3-mediated damage of Vero cells, whereas inhibitors of FAS and the SREBP-1c reduce the viral presence of CVB3 in neonatal cardiomyocytes. CONCLUSION LXR agonism does not modulate cardiac inflammation, but exacerbates virus-mediated myocardial damage during VM by stimulating lipid biosynthesis and enhancing CVB3 replication.
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Affiliation(s)
- Anna-Pia Papageorgiou
- Centre for Molecular and Vascular Biology (CMVB), Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium CArdiovascular Research Institute Maastricht (CARIM), Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Ward Heggermont
- Centre for Molecular and Vascular Biology (CMVB), Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium CArdiovascular Research Institute Maastricht (CARIM), Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Marieke Rienks
- CArdiovascular Research Institute Maastricht (CARIM), Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Paolo Carai
- Centre for Molecular and Vascular Biology (CMVB), Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium CArdiovascular Research Institute Maastricht (CARIM), Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Lies Langouche
- Laboratory of Intensive Care Medicine, KU Leuven, Leuven, Belgium
| | - Wouter Verhesen
- CArdiovascular Research Institute Maastricht (CARIM), Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Rudolf A De Boer
- University Medical Center, Groningen University, Groningen, The Netherlands
| | - Stephane Heymans
- Centre for Molecular and Vascular Biology (CMVB), Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium CArdiovascular Research Institute Maastricht (CARIM), Universiteitssingel 50, 6229 ER Maastricht, The Netherlands ICIN - Netherlands Heart Institute, Utrecht, The Netherlands
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16
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Cannon MV, Yu H, Candido WM, Dokter MM, Lindstedt EL, Silljé HHW, van Gilst WH, de Boer RA. The liver X receptor agonist AZ876 protects against pathological cardiac hypertrophy and fibrosis without lipogenic side effects. Eur J Heart Fail 2015; 17:273-82. [PMID: 25684370 DOI: 10.1002/ejhf.243] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 01/07/2015] [Accepted: 01/08/2015] [Indexed: 11/07/2022] Open
Abstract
AIMS Liver X receptors (LXRs) transcriptionally regulate inflammation, metabolism, and immunity. Synthetic LXR agonists have been evaluated for their efficacy in the cardiovascular system; however, they elicit prolipogenic side effects which substantially limit their therapeutic use. AZ876 is a novel high-affinity LXR agonist. Herein, we aimed to determine the cardioprotective potential of LXR activation with AZ876. METHODS AND RESULTS Cardiac hypertrophy was induced in C57Bl6/J mice via transverse aortic constriction (TAC) for 6 weeks. During this period, mice received chow supplemented or not with AZ876 (20 µmol/kg/day). In murine hearts, LXRα protein expression was up-regulated ∼7-fold in response to TAC. LXR activation with AZ876 attenuated this increase, and significantly reduced TAC-induced increases in heart weight, myocardial fibrosis, and cardiac dysfunction without affecting blood pressure. At the molecular level, AZ876 suppressed up-regulation of hypertrophy- and fibrosis-related genes, and further inhibited prohypertrophic and profibrotic transforming growth factor β (TGFβ)-Smad2/3 signalling. In isolated cardiac myocytes and fibroblasts, immunocytochemistry confirmed nuclear expression of LXRα in both these cell types. In cardiomyocytes, phenylephrine-stimulated cellular hypertrophy was significantly decreased in AZ876-treated cells. In cardiac fibroblasts, AZ876 prevented TGFβ- and angiotensin II-induced fibroblast collagen synthesis, and inhibited up-regulation of the myofibroblastic marker, α-smooth muscle actin. Plasma triglycerides and liver weight were unaltered following AZ876 treatment. CONCLUSION AZ876 activation of LXR protects from adverse cardiac remodelling in pathological pressure overload, independently of blood pressure. LXR may thus represent a putative molecular target for antihypertrophic and antifibrotic therapies in heart failure prevention.
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Affiliation(s)
- Megan V Cannon
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands
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17
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28-Homobrassinolide: a novel oxysterol transactivating LXR gene expression. Mol Biol Rep 2014; 41:7447-61. [PMID: 25091941 DOI: 10.1007/s11033-014-3632-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 07/21/2014] [Indexed: 12/22/2022]
Abstract
Cholesterol is the template for steroid hormone biosynthesis. Cholesterol homeostasis is regulated by Cyt-P450 oxygenated cholesterols acting as ligands on LXR-α and LXR-β transcription factors that are now emerging as drug targets. Heterodimerization of LXRs with retinoic acid receptor is considered a prerequisite for target gene activation. Dietary plant oxysterol 28-homobrassinolide (28-HB) is a proven antihyperglycemic and a pro-steroidogenic agent in the rat. Whether 28-HB has a role in LXR gene expression was therefore investigated using oral gavage (15 days) of 28-HB (333 µg/kg b w) to normal and diabetic rat. PCR amplified LXR-α and β mRNA transcripts from treated rat liver and testis exhibited quantitative differences in their expression. Conformational differences in 28-HB docking to LXR-α and β binding domains were also noted through in silico studies, LXR-β adopting lesser specificity. We report that 28-HB transactivates LXR genes in the rat tissues.
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18
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Rondanino C, Ouchchane L, Chauffour C, Marceau G, Déchelotte P, Sion B, Pons-Rejraji H, Janny L, Volle DH, Lobaccaro JMA, Brugnon F. Levels of liver X receptors in testicular biopsies of patients with azoospermia. Fertil Steril 2014; 102:361-371.e5. [PMID: 24842676 DOI: 10.1016/j.fertnstert.2014.04.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/12/2014] [Accepted: 04/18/2014] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine whether the transcription factors liver X receptors (LXRs) and their downstream genes, which are involved in the regulation of several testicular functions in mouse models, are differentially expressed in testes of men with nonobstructive azoospermia (NOA) or obstructive azoospermia (OA). DESIGN Prospective study. SETTING University hospital. PATIENT(S) Patients with various types of NOA (n=22) and with OA (n=5). INTERVENTION(S) Human testicular biopsies. MAIN OUTCOME MEASURE(S) Transcript levels were measured in testicular biopsies with the use of quantitative polymerase chain reaction. Correlations of LXR mRNA levels with the number of germ cells, the expression of proliferation and apoptosis markers, and the amount of intratesticular lipids and testosterone were evaluated. The localization of LXRα was analyzed by immunofluorescence. RESULT(S) LXR mRNA levels were decreased by 49%-98% in NOA specimens and positively correlated with germ cell number. Accumulations of IDOL and SREBP1c (LXR targets involved in lipid homeostasis) were 1.8-2.1 times lower in NOA samples and mRNA levels of the SREBP1c target gene ELOVL6 were increased 1.9-2.4-fold. Interestingly, the amount of triglycerides and free fatty acids were higher in NOA testes (3.4-12.2-fold). LXRα was present in Leydig cells. Accumulations of LXR downstream genes encoding the steroidogenic proteins StAR and 3βHSD2 were higher in NOA testes (5.9-12.8-fold). CONCLUSION(S) Knowledge of changes in the transcript levels of LXRs and some of their downstream genes during altered spermatogenesis may help us to better understand the physiopathology of testicular failure in azoospermic patients.
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Affiliation(s)
- Christine Rondanino
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; Centre de Recherche en Nutrition Humaine d'Auvergne, Clermont-Ferrand, France; AMP-CECOS, CHU Clermont-Ferrand, CHU Estaing, Clermont-Ferrand, France
| | - Lemlih Ouchchane
- Laboratoire ISIT, UMR 6284 Université d'Auvergne-CNRS, Clermont-Ferrand, France; Service de Biostatistiques, Clermont-Ferrand, France
| | - Candice Chauffour
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; Centre de Recherche en Nutrition Humaine d'Auvergne, Clermont-Ferrand, France; AMP-CECOS, CHU Clermont-Ferrand, CHU Estaing, Clermont-Ferrand, France
| | - Geoffroy Marceau
- Laboratoire de Biochimie, CHU Clermont-Ferrand, Clermont-Ferrand, France
| | - Pierre Déchelotte
- Service d'Anatomie Pathologique, CHU Clermont-Ferrand, CHU Estaing, Clermont-Ferrand, France
| | - Benoît Sion
- Laboratoire NEURO-DOL, INSERM U 1107, Clermont-Ferrand, France; Laboratoire de Pharmacologie Fondamentale et Clinique de la Douleur, Université d'Auvergne, Clermont-Ferrand, France
| | - Hanae Pons-Rejraji
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; AMP-CECOS, CHU Clermont-Ferrand, CHU Estaing, Clermont-Ferrand, France
| | - Laurent Janny
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; AMP-CECOS, CHU Clermont-Ferrand, CHU Estaing, Clermont-Ferrand, France
| | - David H Volle
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; Centre de Recherche en Nutrition Humaine d'Auvergne, Clermont-Ferrand, France
| | - Jean-Marc A Lobaccaro
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; Centre de Recherche en Nutrition Humaine d'Auvergne, Clermont-Ferrand, France
| | - Florence Brugnon
- Génétique Reproduction et Développement, Clermont Université, Clermont-Ferrand, France; CNRS, UMR 6293, GReD, Aubière, France; INSERM, UMR 1103, GReD, Aubière, France; AMP-CECOS, CHU Clermont-Ferrand, CHU Estaing, Clermont-Ferrand, France.
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19
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Kuipers I, Li J, Vreeswijk-Baudoin I, Koster J, van der Harst P, Silljé HH, Kuipers F, van Veldhuisen DJ, van Gilst WH, de Boer RA. Activation of liver X receptors with T0901317 attenuates cardiac hypertrophyin vivo. Eur J Heart Fail 2014; 12:1042-50. [DOI: 10.1093/eurjhf/hfq109] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Irma Kuipers
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Jiang Li
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Inge Vreeswijk-Baudoin
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Johan Koster
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Pim van der Harst
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Herman H.W. Silljé
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Folkert Kuipers
- Department of Experimental Pediatrics; University Medical Center Groningen; Groningen The Netherlands
| | - Dirk J. van Veldhuisen
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Wiek H. van Gilst
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
| | - Rudolf A. de Boer
- Department of Experimental Cardiology; University Medical Center Groningen; PO Box 30.001, 9700 RB Groningen The Netherlands
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20
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Maqdasy S, Baptissart M, Vega A, Baron S, Lobaccaro JMA, Volle DH. Cholesterol and male fertility: what about orphans and adopted? Mol Cell Endocrinol 2013; 368:30-46. [PMID: 22766106 DOI: 10.1016/j.mce.2012.06.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 06/20/2012] [Accepted: 06/21/2012] [Indexed: 12/24/2022]
Abstract
The link between cholesterol homeostasis and male fertility has been clearly suggested in patients who suffer from hyperlipidemia and metabolic syndrome. This has been confirmed by the generation of several transgenic mouse models or in animals fed with high cholesterol diet. Next to the alteration of the endocrine signaling pathways through steroid receptors (androgen and estrogen receptors); "orphan" and "adopted" nuclear receptors, such as the Liver X Receptors (LXRs), the Proliferating Peroxisomal Activated Receptors (PPARs) or the Liver Receptor Homolog-1 (LRH-1), have been involved in this cross-talk. These transcription factors show distinct expression patterns in the male genital tract, explaining the large panel of phenotypes observed in transgenic male mice and highlighting the importance of lipid homesostasis and the complexity of the molecular pathways involved. Increasing our knowledge of the roles of these nuclear receptors in male germ cell differentiation could help in proposing new approaches to either treat infertile men or define new strategies for contraception.
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21
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Hyter S, Indra AK. Nuclear hormone receptor functions in keratinocyte and melanocyte homeostasis, epidermal carcinogenesis and melanomagenesis. FEBS Lett 2013; 587:529-41. [PMID: 23395795 PMCID: PMC3670764 DOI: 10.1016/j.febslet.2013.01.041] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 12/12/2012] [Accepted: 01/18/2013] [Indexed: 12/19/2022]
Abstract
Skin homeostasis is maintained, in part, through regulation of gene expression orchestrated by type II nuclear hormone receptors in a cell and context specific manner. This group of transcriptional regulators is implicated in various cellular processes including epidermal proliferation, differentiation, permeability barrier formation, follicular cycling and inflammatory responses. Endogenous ligands for the receptors regulate actions during skin development and maintenance of tissue homeostasis. Type II nuclear receptor signaling is also important for cellular crosstalk between multiple cell types in the skin. Overall, these nuclear receptors are critical players in keratinocyte and melanocyte biology and present targets for cutaneous disease management.
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Affiliation(s)
- Stephen Hyter
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA
| | - Arup K Indra
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon, USA
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA
- Environmental Health Science Center, Oregon State University, Corvallis, Oregon, USA
- Department of Dermatology, Oregon Health and Science University, Portland, Oregon, USA
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22
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 504] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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23
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Abstract
Liver X receptors (LXRs) belong to the nuclear receptor superfamily of ligand-dependent transcription factors. LXRs are activated by oxysterols, metabolites of cholesterol, and therefore act as intracellular sensors of this lipid. There are two LXR genes (α and β) that display distinct tissue/cell expression profiles. LXRs interact with regulatory sequences in target genes as heterodimers with retinoid X receptor. Such direct targets of LXR actions include important genes implicated in the control of lipid homeostasis, particularly reverse cholesterol transport. In addition, LXRs attenuate the transcription of genes associated with the inflammatory response indirectly by transrepression. In this review, we describe recent evidence that both highlights the key roles of LXRs in atherosclerosis and inflammation and provides novel insights into the mechanisms underlying their actions. In addition, we discuss the major limitations of LXRs as therapeutic targets for the treatment of atherosclerosis and how these are being addressed.
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24
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Nagy L, Szanto A, Szatmari I, Széles L. Nuclear hormone receptors enable macrophages and dendritic cells to sense their lipid environment and shape their immune response. Physiol Rev 2012; 92:739-89. [PMID: 22535896 DOI: 10.1152/physrev.00004.2011] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A key issue in the immune system is to generate specific cell types, often with opposing activities. The mechanisms of differentiation and subtype specification of immune cells such as macrophages and dendritic cells are critical to understand the regulatory principles and logic of the immune system. In addition to cytokines and pathogens, it is increasingly appreciated that lipid signaling also has a key role in differentiation and subtype specification. In this review we explore how intracellular lipid signaling via a set of transcription factors regulates cellular differentiation, subtype specification, and immune as well as metabolic homeostasis. We introduce macrophages and dendritic cells and then we focus on a group of transcription factors, nuclear receptors, which regulate gene expression upon receiving lipid signals. The receptors we cover are the ones with a recognized physiological function in these cell types and ones which heterodimerize with the retinoid X receptor. These are as follows: the receptor for a metabolite of vitamin A, retinoic acid: retinoic acid receptor (RAR), the vitamin D receptor (VDR), the fatty acid receptor: peroxisome proliferator-activated receptor γ (PPARγ), the oxysterol receptor liver X receptor (LXR), and their obligate heterodimeric partner, the retinoid X receptor (RXR). We discuss how they can get activated and how ligand is generated and eliminated in these cell types. We also explore how activation of a particular target gene contributes to biological functions and how the regulation of individual target genes adds up to the coordination of gene networks. It appears that RXR heterodimeric nuclear receptors provide these cells with a coordinated and interrelated network of transcriptional regulators for interpreting the lipid milieu and the metabolic changes to bring about gene expression changes leading to subtype and functional specification. We also show that these networks are implicated in various immune diseases and are amenable to therapeutic exploitation.
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Affiliation(s)
- Laszlo Nagy
- Department of Biochemistry and Molecular Biology, University of Debrecen, Medical and Health Science Center, Egyetem tér 1, Debrecen, Hungary.
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25
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Endo-Umeda K, Uno S, Fujimori K, Naito Y, Saito K, Yamagishi K, Jeong Y, Miyachi H, Tokiwa H, Yamada S, Makishima M. Differential Expression and Function of Alternative Splicing Variants of Human Liver X Receptor α. Mol Pharmacol 2012; 81:800-10. [DOI: 10.1124/mol.111.077206] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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26
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Abstract
Liver X receptors (LXRs) are members of the nuclear receptor family and are present in two isoforms, α and β, encoded by two separate genes. Originally described in the liver, LXRs have in the last 15 years been implicated in central metabolic pathways, including bile acid synthesis, lipid and glucose homeostasis. Although the vast majority of studies have been performed in non-adipose cells/tissues, results in recent years suggest that LXRs may have important modulatory roles in adipose tissue and adipocytes. Although several authors have published reviews on LXR, there have been no attempts to summarize the effects reported specifically in adipose systems. This overview gives a brief introduction to LXR and describes the sometimes-contradictory results obtained in murine cell systems and in rodent adipose tissue. The so far very limited number of studies performed in human adipocytes and adipose tissue are also presented. It should be apparent that although LXR may impact on several different pathways in metabolism, the clinical role of LXR modulation in adipose tissue is still not clear.
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27
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Price ET, Pacanowski MA, Martin MA, Cooper-DeHoff RM, Pepine CJ, Zineh I, Johnson JA. Liver X receptor α gene polymorphisms and variable cardiovascular outcomes in patients treated with antihypertensive therapy: results from the INVEST-GENES study. Pharmacogenet Genomics 2011; 21:333-40. [PMID: 21562465 DOI: 10.1097/fpc.0b013e3283452fec] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND/AIMS Liver X receptor-α (LXRA) is a nuclear receptor that regulates genes important in cholesterol homeostasis and inflammation. Several single nucleotide polymorphisms (SNPs) in the LXRA gene (NR1H3) have been earlier associated with metabolic phenotypes (dyslipidemia and elevated body mass index). Metabolic dysregulation is a major contributor to coronary disease; therefore, we assessed LXRA in International Verapamil Sustained Release SR Trandolapril Study Genetic Substudy (INVEST-GENES), a genetic-substudy of a large clinical trial in patients with hypertension and coronary artery disease. METHODS Seven tag SNPs in the LXRA gene region (NR1H3) were selected for study: rs11039149, rs12221497, rs2279238, rs7120118, rs326213, rs11039159, and rs10501321. One thousand fifty-nine patients were genotyped from the INVEST-GENES case-control set (verapamil-sustained release-based or atenolol-based treatment strategies) that comprised of 297 cases frequency matched (approximately 2.5:1) with that of event-free controls by sex and race. The primary outcome was defined as first occurrence of all-cause death, nonfatal myocardial infarction, or nonfatal stroke. Adjusted odds ratios (ORs) were calculated using logistic regression. RESULTS Three of the seven SNPs were associated with significant effects on the primary outcome in nonBlacks. The variant G allele of rs11039149 and the variant A allele of rs12221497 were associated with reduced risk of experiencing the primary outcome [OR: 0.62, confidence interval (CI): 0.45-0.85, P=0.003 and OR: 0.60, CI: 0.39-0.91, P=0.016, respectively]. The rs2279238 genotype was associated with a significant increase in risk for the primary outcome (OR: 1.42, CI: 1.03-1.95, P=0.03). Furthermore, there was a significant genotype-treatment strategy interaction for carriers of the variant T allele of rs2279238 (OR for verapamil-sustained release strategy compared with atenolol strategy: 2.86, CI: 1.50-5.46, P=0.0015). Diplotype analyses showed that the SNPs are rarely coinherited and support the directionally opposite effects of the SNPs on the primary outcome. CONCLUSION LXRA genotypes were associated with variable risk for cardiovascular outcomes and pharmacogenetic effect in INVEST-GENES. These novel findings suggest that LXRA is a genetic/pharmacogenetic target that should be further explored.
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Affiliation(s)
- Elvin Tyrone Price
- Department of Pharmacotherapy and Translational Research and Center for Pharmacogenomics, University of Florida College of Medicine, Gainesville, FL, USA
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28
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El-Hajjaji FZ, Oumeddour A, Pommier AJC, Ouvrier A, Viennois E, Dufour J, Caira F, Drevet JR, Volle DH, Baron S, Saez F, Lobaccaro JMA. Liver X receptors, lipids and their reproductive secrets in the male. Biochim Biophys Acta Mol Basis Dis 2011; 1812:974-81. [PMID: 21334438 DOI: 10.1016/j.bbadis.2011.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 02/07/2011] [Accepted: 02/11/2011] [Indexed: 12/31/2022]
Abstract
Liver X receptor (LXR) α and LXRβ belong to the nuclear receptor superfamily. For many years, they have been called orphan receptors, as no natural ligand was identified. In the last decade, the LXR natural ligands have been shown to be oxysterols, molecules derived from cholesterol. While these nuclear receptors have been abundantly studied for their roles in the regulation of lipid metabolism, it appears that they also present crucial activities in reproductive organs such as testis and epididymis, as well as prostate. Phenotypic analyses of mice lacking LXRs (lxr-/-) pointed out their physiological activities in the various cells and organs regulating reproductive functions. This review summarizes the impact of LXR-deficiency in male reproduction, highlighting the novel information coming from the phenotypic analyses of lxrα-/-, lxrβ-/- and lxrα;β-/- mice. This article is part of a Special Issue entitled: Translating nuclear receptor from health to disease.
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Affiliation(s)
- Fatim-Zorah El-Hajjaji
- CNRS Unité Mixte de Recherche 6247 Génétique, Reproduction et Développement, F-63171 Aubière, France
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29
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Dave VP, Kaul D. Coronary heart disease: Significance of liver X receptor α genomics. World J Cardiol 2010; 2:140-9. [PMID: 21160732 PMCID: PMC2999051 DOI: 10.4330/wjc.v2.i6.140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 06/11/2010] [Accepted: 06/18/2010] [Indexed: 02/06/2023] Open
Abstract
Crosstalk between lipid peroxidation and inflammation is known to be a pathognomonic feature for the development of coronary heart disease (CHD). In this regard ligand activated liver X receptor (LXR)-α has emerged as a key molecular switch by its inherent ability to modulate an array of genes involved in these two fundamental cellular processes. In addition, LXR-α has also been found to play a role in hepatic lipogenesis and innate immunity. Although several lines of evidence in experimental model systems have established the atheroprotective nature of LXR-α, human subjects have been reported to possess a paradoxical situation in which increased blood cellular LXR-α gene expression is always accompanied by increased coronary occlusion. This apparent paradox was resolved recently by the finding that CHD patients possess a deregulated LXR-α transcriptome due to impaired ligand-receptor interaction. This blood cellular mutated LXR-α gene expression correlated specifically with the extent of coronary occlusion and hence need is felt to devise new synthetic ligands that could restore the function of this mutated LXR-α protein in order to modulate genes involved in reverse cholesterol transport and suppression of the inflammatory response leading to the effective treatment of CHD.
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Affiliation(s)
- Vivek Priy Dave
- Vivek Priy Dave, Deepak Kaul, Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Education and Research, Chandigarh 160012, India
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Interplay between cholesterol and drug metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:146-60. [PMID: 20570756 DOI: 10.1016/j.bbapap.2010.05.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/17/2010] [Accepted: 05/24/2010] [Indexed: 12/14/2022]
Abstract
Cholesterol biosynthetic and metabolic pathways contain several branching points towards physiologically active molecules, such as coenzyme Q, vitamin D, glucocorticoid and steroid hormones, oxysterols, or bile acids. Sophisticated regulatory mechanisms are involved in maintenance of the homeostasis of not only cholesterol but also other cholesterogenic molecules. In addition to endogenous cues, cholesterol homeostasis needs to accommodate also to exogenous cues that are imported into the body, such as chemicals and medications. Steroid and nuclear receptors together with sterol regulatory element-binding protein (SREBP) mediate the fine tuning of biosynthetic and metabolic routes as well as transports of cholesterol and its derivatives. Similarly, drug/xenobiotic metabolism is the subject to the feedback regulation of cytochrome P450 enzymes and transporters. The regulatory mechanisms that maintain the homeostasis of cholesterogenic molecules and are involved in drug metabolism share similarities. Cholesterol and cholesterogenic compounds (bile acids, glucocorticoids, vitamin D, etc.) regulate the xenosensor signaling in drug-mediated induction of the major drug-metabolizing cytochrome P450 enzymes. The key cellular receptors, pregnane X receptor (PXR), constitutive androstane receptor (CAR), vitamin D receptor (VDR), and glucocorticoid receptor (GR) provide a functional cross-talk between the pathways maintaining cholesterol homeostasis and controlling the expression of drug-metabolizing enzymes. These receptors serve as metabolic sensors, resulting in a coordinate regulation of cholesterogenic compounds metabolism and of the defense against xenobiotic and endobiotic toxicity. Herein we present a comprehensive review of functional interactions between cholesterol homeostasis and drug metabolism involving the main nuclear and steroid receptors.
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31
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Kuipers I, van der Harst P, Kuipers F, van Genne L, Goris M, Lehtonen JY, van Veldhuisen DJ, van Gilst WH, de Boer RA. Activation of liver X receptor-alpha reduces activation of the renal and cardiac renin-angiotensin-aldosterone system. J Transl Med 2010; 90:630-6. [PMID: 20125084 DOI: 10.1038/labinvest.2010.7] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Liver X receptor (LXR)-alpha is a pivotal player in reverse cholesterol metabolism. Recently, LXR-alpha was implicated as an immediate regulator of renin expression in a cAMP-responsive manner. To determine whether long-term LXR-alpha activation affects activation of the renal and cardiac renin-angiotensin-aldosterone system (RAAS), we treated mice with T0901317 (T09, a specific synthetic LXR agonist) in combination with the RAAS inducer isoproterenol (ISO). LXR-alpha-deficient (LXR-alpha(-/-)) and wild-type (WT) C57Bl/6J mice were treated with ISO, T09 or both for 7 days. Low-dose ISO treatment, not associated with an increase in blood pressure, caused an increase in renal renin mRNA, renin protein and ACE protein in WT mice. WT mice treated with both ISO and T09 had decreased renal renin, ACE and AT(1)R mRNA expression compared with mice treated with ISO only. Cardiac ACE mRNA expression was also reduced in the hearts of WT mice treated with ISO and T09 compared with those treated with ISO alone. The transcriptional changes of renin, ACE and AT(1)R were mostly absent in mice deficient for LXR-alpha, suggesting that these effects are importantly conferred through LXR-alpha. In conclusion, LXR-alpha activation blunts ISO-induced increases in mRNA expression of renin, AT(1)R and ACE in the heart and kidney. These findings suggest a role for LXR-alpha in RAAS regulation.
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Affiliation(s)
- Irma Kuipers
- Department of Experimental Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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32
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Liu JP. New functions of cholesterol binding proteins. Mol Cell Endocrinol 2009; 303:1-6. [PMID: 19428985 DOI: 10.1016/j.mce.2009.01.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 01/10/2009] [Accepted: 01/12/2009] [Indexed: 11/22/2022]
Abstract
Cholesterol is an essential component of eukaryotic cell membranes with an important role in signal transduction. Although cholesterol can operate to auto-regulate its own disposal via gene transcriptional mechanisms, glucose also binds to the same cholesterol-binding transcription factors to regulate gene expression. Different sterol binding proteins bind different lipids to regulate both lipid homeostasis and antigen presentation. This mini-review examines the recently reported new functions of cholesterol binding proteins in cholesterol homeostasis, function and trafficking, and explores the molecular mechanisms whereby sterol sensors respond to glucose and other ligands to regulate diverse cellular functions in metabolism. Several new models are proposed from studies on a range of sterol binding proteins including Insig, SCAP, LXR, HMG-CoAR, NPC1 and NPC2.
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Affiliation(s)
- Jun-Ping Liu
- Department of Immunology, Monash University Central Clinical School, Prahran, Victoria, Australia.
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33
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Cruz-Garcia L, Minghetti M, Navarro I, Tocher DR. Molecular cloning, tissue expression and regulation of liver X receptor (LXR) transcription factors of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Comp Biochem Physiol B Biochem Mol Biol 2009; 153:81-8. [PMID: 19416695 DOI: 10.1016/j.cbpb.2009.02.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 01/30/2009] [Accepted: 02/02/2009] [Indexed: 11/28/2022]
Abstract
Fish are important sources of high quality protein, essential minerals such as iodine and selenium, vitamins including A, D and E, and omega-3 fatty acids in the human diet. With declining fisheries worldwide, farmed fish constitute an ever-increasing proportion of fish in the food basket. Sustainable development of aquaculture dictates that diets will have to contain increasing levels of plant products that are devoid of cholesterol, but contain phytosterols that are known to have physiological effects in mammals. Liver X receptors (LXR) are transcription factors whose activity is modulated by sterols, with activation inducing cholesterol catabolism and de novo fatty acid biosynthesis in liver. Transcriptomic analysis has shown that substitution of fish meal and oil with plant products induces genes of cholesterol and fatty acid metabolism in salmonids. Here we report the cloning of LXR cDNAs from two species of salmonid fish that are important in aquaculture. The full-length cDNA (mRNA) of LXR obtained from salmon was shown to be 3766 bp, which included a 5'-untranslated region (UTR) of 412 bp and a 3'-UTR of 1960 bp and an open reading frame (ORF) of 1394 bp, which specified a protein of 462 amino acids. The trout LXR full-length cDNA was 2056 bp, including 5'- and 3'-UTRs of 219 and 547 bp, respectively, and an ORF of 1290 bp, which specified a protein of 427 amino acids. The protein sequences included characteristic features of mammalian LXRs, including the DNA binding (DBD), containing P-box, ligand binding (LBD) and activation function-2 (AF-2) domains, D-box, D (hinge) region, and eight cysteines that belong to the two zinc fingers. Phylogenetic analysis clustered the salmonid LXRs together, more closely with zebrafish and more distantly from medaka and stickleback. A pair-wise comparison among vertebrate LXR sequences showed the amino acid sequence predicted by the salmon LXR ORF showed greatest identity to that of trout 97%, and 97%, 87% and 81% identity to LXRs of zebrafish, frog and human (LXRalpha). The trout LXR ORF showed 96%, 92% and 82% identity to LXRs of zebrafish, frog and human (LXRalpha). Surprisingly, the expression of LXR was lowest in liver of all tissues examined and in salmon the greatest expression was observed in pyloric caeca with liver showing intermediate expression. It is likely that tissue expression was affected by the physiological status of the sampled animals. Certainly, nutritional, environmental and/or developmental regulation was evident in salmon, where the expression of LXR in liver was higher in fish in seawater than in freshwater, and higher in fish fed fish oil compared to fish fed vegetable oil in adult salmon.
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Affiliation(s)
- L Cruz-Garcia
- Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
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Miller A, Crumbley C, Prüfer K. The N-terminal nuclear localization sequences of liver X receptors alpha and beta bind to importin alpha and are essential for both nuclear import and transactivating functions. Int J Biochem Cell Biol 2008; 41:834-43. [PMID: 18773967 DOI: 10.1016/j.biocel.2008.08.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/05/2008] [Accepted: 08/12/2008] [Indexed: 01/27/2023]
Abstract
Liver X receptors (LXRs) alpha and beta are nuclear receptors, which form obligate heterodimers with the retinoid X receptor (RXR). The LXRs regulate both redundantly and non-redundantly the transcription of genes controlling cholesterol metabolism and transport as well as lipogenesis. Previously, we showed that mutations in putative N-terminal nuclear localization sequences (NLSs) within both LXRs inhibit nuclear import. Through in vitro studies, we show here that these NLSs bind importin alpha and are both necessary and sufficient for the nuclear import of LXRs. Imaging, transactivation, and electro-mobility shift experiments show that RXR rescues the nuclear import of the LXRalpha NLS mutant yet does not restore its transcriptional activity despite intact DNA binding. In contrast, RXR partially rescues the import of the LXRbeta NLS mutant, but has no effect on its transcriptional activity due to the loss of DNA binding. Experiments with NLS mutant RXR confirmed that RXR may dominate the nuclear import of the RXR/LXRalpha heterodimer, whereas LXRbeta dominates the nuclear import of the RXR/LXRbeta heterodimer. Intriguingly, our data indicate differences between LXRalpha and LXRbeta in their interaction with RXR and in the role their NLSs play in transactivating functions independent of nuclear import.
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Affiliation(s)
- Anna Miller
- Department of Biological Sciences, A243 Life Science Building, Louisiana State University, Baton Rouge, LA 70803, USA
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Russell LE, Harrison WJ, Bahta AW, Zouboulis CC, Burrin JM, Philpott MP. Characterization of liver X receptor expression and function in human skin and the pilosebaceous unit. Exp Dermatol 2007; 16:844-52. [PMID: 17845217 DOI: 10.1111/j.1600-0625.2007.00612.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The nuclear receptors liver X receptor alpha (LXRalpha) and liver X-receptor beta (LXRbeta) have a well documented role in cholesterol homeostasis and lipid metabolism within tissues and cells including the liver, small intestine and macrophages. In keratinocytes, LXRs have been shown to up-regulate differentiation in vitro via increased transcription of proteins of the AP1 complex and to down-regulate proliferation in vivo. In this study, we provide a detailed description of the location and possible role of LXRs within human skin and its associated glands and appendages. Using RT-PCR, Western blotting and immunohistochemistry, we have demonstrated expression of LXRalpha and LXRbeta mRNA and proteins in whole human skin as well as within a range of primary and immortalized human cell lines derived from human skin, hair follicle and sebaceous glands. Furthermore, we have shown that synthetic LXR specific agonists GW683965 and TO901317 significantly inhibit cell proliferation in primary epidermal keratinocytes, immortalized N/TERT keratinocytes and the immortalized SZ95 sebocyte line, and significantly increase lipogenesis in SZ95 sebocytes. In addition, we showed that the synthetic agonist TO901317 significantly reduced hair growth, in vitro.
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Affiliation(s)
- Louise E Russell
- Centre for Cutaneous Research and Centre for Endocrinology, Bart's and The London Queen Mary's School of Medicine and Dentistry, Queen Mary College, University of London, London, UK
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Iyer AK, Zhang YH, McCabe ER. LXXLL motifs and AF-2 domain mediate SHP (NR0B2) homodimerization and DAX1 (NR0B1)-DAX1A heterodimerization. Mol Genet Metab 2007; 92:151-9. [PMID: 17686645 PMCID: PMC2065763 DOI: 10.1016/j.ymgme.2007.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Accepted: 06/20/2007] [Indexed: 11/30/2022]
Abstract
Small heterodimer partner (SHP; NR0B2) is an unusual orphan member of the nuclear receptor superfamily that functions as a corepressor of other nuclear receptors through heterodimeric interactions. Mutations in SHP are associated with mild obesity and insulin resistance. The protein domain structure of SHP is similar to Dosage-sensitive sex reversal adrenal hypoplasia congenita (AHC) critical region on the X chromosome, gene 1 (DAX1; NR0B1). Mutations in DAX1 cause AHC with associated hypogonadotropic hypogonadism. DAX1A is an alternatively spliced isoform of DAX1 that lacks the last 80 amino acids of the DAX1 C-terminal repressor domain and is replaced by a novel 10-amino acid motif. We have previously shown homodimerization of SHP and DAX1 individually, heterodimerization of DAX1 with SHP, and heterodimerization of DAX1 with DAX1A. In these studies, we investigated the domains and residues of SHP involved in SHP homodimerization and DAX1-SHP heterodimerization and also further characterized DAX1-DAX1 homodimerization and DAX1-DAX1A heterodimerization. We showed involvement of the SHP LXXLL motifs and AF-2 domain in SHP homodimerization and DAX1-SHP heterodimerization. We demonstrated redundancy of the LXXLL motifs in DAX1 homodimerization. While DAX1A subcellular localization is mostly cytoplasmic, DAX1-DAX1A heterodimers existed in the nucleus, suggesting differential functions for DAX1A in each compartment. We showed that the AF-2 domain of DAX1 is involved in DAX1-DAX1A heterodimerization. These results indicate that NR0B family members use similar mechanisms for homodimerization as well as heterodimerization. These resemble coactivator-receptor interactions that may have potential functional consequences for molecular mechanisms of the NR0B family.
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Affiliation(s)
- Anita K. Iyer
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Corresponding author: E.R.B. McCabe, M.D., Ph.D., Department of Pediatrics, 22-412 MDCC, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA, 90095-1752, USA. Phone 310-825-5095, Fax 310-206-4584, Email
| | - Yao-Hua Zhang
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Edward R.B. McCabe
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Mattel Children's Hospital at UCLA
- UCLA Molecular Biology Institute, Los Angeles, CA, USA
- Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, UCLA, Los Angeles, CA, USA
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Dahlman I, Nilsson M, Jiao H, Hoffstedt J, Lindgren CM, Humphreys K, Kere J, Gustafsson JA, Arner P, Dahlman-Wright K. Liver X receptor gene polymorphisms and adipose tissue expression levels in obesity. Pharmacogenet Genomics 2007; 16:881-9. [PMID: 17108812 DOI: 10.1097/01.fpc.0000236334.49422.48] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE LXRA and LXRB genes regulate adiposity, energy dissipation, as well as glucose and lipid homeostasis in mice. We investigated the LXR genes in human obesity. METHODS LXRA and LXRB mRNAs were quantified in abdominal subcutaneous adipose tissue of obese and nonobese women. The LXRA and LXRB genes were screened for polymorphisms and common single nucleotide polymorphisms genotyped in obese and nonobese women. RESULTS Relative LXRA mRNA expression levels were higher in obese women (P=0.03). One LXRA single nucleotide polymorphism, rs2279238, and one common haplotype, CAAGCC, as well as two LXRB single nucleotide polymorphisms, LB44732G>A and rs2695121, were associated with obesity phenotypes (nominal P values of 0.0075, 0.0014, 0.008 and 0.02, respectively). Furthermore, there was evidence of interaction between LXRA and LXRB alleles in determining body mass index. CONCLUSION Our results support a role for LXRA in human adipose tissue. The nominal associations of LXRA and LXRB alleles with obesity are interesting and should be further investigated in independent data sets.
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Affiliation(s)
- Ingrid Dahlman
- Department of Medicine, Karolinska Institute, Huddinge, Stockholm, Sweden.
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Chen M, Bradley MN, Beaven SW, Tontonoz P. Phosphorylation of the liver X receptors. FEBS Lett 2006; 580:4835-41. [PMID: 16904112 DOI: 10.1016/j.febslet.2006.07.074] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Revised: 07/21/2006] [Accepted: 07/25/2006] [Indexed: 11/28/2022]
Abstract
The liver X receptors (LXRs) function as nutritional sensors for cholesterol and have important roles in lipid metabolism, glucose homeostasis, and inflammation. We provide the first evidence that LXRs are phosphorylated proteins. Mutational analysis and metabolic labeling indicate LXRalpha is phosphorylated on serine 198 in the hinge region. This is a consensus target for the MAPK family. A phosphorylation-deficient mutant, LXRalpha S198A, remains nuclear and responds to ligands like the wild-type protein. The biological significance of LXR phosphorylation remains to be elucidated but could provide a novel mechanism for the regulation of LXR signaling pathways and cellular metabolism.
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Affiliation(s)
- Mingyi Chen
- Department of Pathology and Laboratory Medicine, University of California-Los Angeles, CA 90095, USA
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Iyer AK, Zhang YH, McCabe ERB. Dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX1) (NR0B1) and small heterodimer partner (SHP) (NR0B2) form homodimers individually, as well as DAX1-SHP heterodimers. Mol Endocrinol 2006; 20:2326-42. [PMID: 16709599 DOI: 10.1210/me.2005-0383] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX1) (NR0B1), and small heterodimer partner (SHP) (NR0B2) are atypical nuclear receptor superfamily members that function primarily as corepressors through heterodimeric interactions with other nuclear receptors. Mutations in DAX1 cause adrenal hypoplasia congenita, and mutations in SHP lead to mild obesity and insulin resistance, but the mechanisms are unclear. We investigated the existence and subcellular localization of DAX1 and SHP homodimers and the dynamics of homodimerization. We demonstrated DAX1 homodimerization in the nucleus and cytoplasm, and dissociation of DAX1 homodimers upon heterodimerization with steroidogenic factor 1 (SF1) or ligand-activated estrogen receptor-alpha (ERalpha). DAX1 homodimerization involved an interaction between its amino and carboxy termini involving its LXXLL motifs and activation function (AF)-2 domain. We observed SHP homodimerization in the nucleus of mammalian cells and showed dissociation of SHP homodimers upon heterodimerization with ligand-activated ERalpha. We observed DAX1-SHP heterodimerization in the nucleus of mammalian cells and demonstrated the involvement of the LXXLL motifs and AF-2 domain of DAX1 in this interaction. We further demonstrate heterodimerization of DAX1 with its alternatively spliced isoform, DAX1A. This is the first evidence of homodimerization of individual members of the unusual NR0B nuclear receptor family and heterodimerization between its members. Our results suggest that DAX1 forms antiparallel homodimers through the LXXLL motifs and AF-2 domain. These homodimers may function as holding reservoirs in the absence of heterodimeric partners. The formation of DAX1 and SHP homodimers and DAX1-SHP and DAX1-DAX1A heterodimers suggests the possibility of novel functions independent of their coregulator roles, suggesting additional complexity in the molecular mechanisms of DAX1 and SHP action.
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Affiliation(s)
- Anita K Iyer
- Department of Human Genetics, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California 90095-1752, USA
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Steffensen KR, Gustafsson JÅ. Liver X receptors: new drug targets to treat Type 2 diabetes? ACTA ACUST UNITED AC 2006. [DOI: 10.2217/17460875.1.2.181] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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