1
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Zhou E, Ge X, Nakashima H, Li R, van der Zande HJP, Liu C, Li Z, Müller C, Bracher F, Mohammed Y, de Boer JF, Kuipers F, Guigas B, Glass CK, Rensen PCN, Giera M, Wang Y. Inhibition of DHCR24 activates LXRα to ameliorate hepatic steatosis and inflammation. EMBO Mol Med 2023; 15:e16845. [PMID: 37357756 PMCID: PMC10405065 DOI: 10.15252/emmm.202216845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/27/2023] Open
Abstract
Liver X receptor (LXR) agonism has theoretical potential for treating NAFLD/NASH, but synthetic agonists induce hyperlipidemia in preclinical models. Desmosterol, which is converted by Δ24-dehydrocholesterol reductase (DHCR24) into cholesterol, is a potent endogenous LXR agonist with anti-inflammatory properties. We aimed to investigate the effects of DHCR24 inhibition on NAFLD/NASH development. Here, by using APOE*3-Leiden. CETP mice, a well-established translational model that develops diet-induced human-like NAFLD/NASH characteristics, we report that SH42, a published DHCR24 inhibitor, markedly increases desmosterol levels in liver and plasma, reduces hepatic lipid content and the steatosis score, and decreases plasma fatty acid and cholesteryl ester concentrations. Flow cytometry showed that SH42 decreases liver inflammation by preventing Kupffer cell activation and monocyte infiltration. LXRα deficiency completely abolishes these beneficial effects of SH42. Together, the inhibition of DHCR24 by SH42 prevents diet-induced hepatic steatosis and inflammation in a strictly LXRα-dependent manner without causing hyperlipidemia. Finally, we also showed that SH42 treatment decreased liver collagen content and plasma alanine transaminase levels in an established NAFLD model. In conclusion, we anticipate that pharmacological DHCR24 inhibition may represent a novel therapeutic strategy for treatment of NAFLD/NASH.
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Affiliation(s)
- Enchen Zhou
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
- Department of Cellular and Molecular Medicine and Department of MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Xiaoke Ge
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
| | - Hiroyuki Nakashima
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
| | - Rumei Li
- Department of PediatricsUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | | | - Cong Liu
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
| | - Zhuang Li
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
| | - Christoph Müller
- Department of Pharmacy, Center for Drug ResearchLudwig Maximilians UniversityMunichGermany
| | - Franz Bracher
- Department of Pharmacy, Center for Drug ResearchLudwig Maximilians UniversityMunichGermany
| | - Yassene Mohammed
- The Center for Proteomics and MetabolomicsLeiden University Medical CenterLeidenThe Netherlands
| | - Jan Freark de Boer
- Department of PediatricsUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
- Department of Laboratory MedicineUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | - Folkert Kuipers
- Department of PediatricsUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
- Department of Laboratory MedicineUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | - Bruno Guigas
- Department of ParasitologyLeiden University Medical CenterLeidenThe Netherlands
| | - Christopher K Glass
- Department of Cellular and Molecular Medicine and Department of MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Patrick C N Rensen
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
- Med‐X Institute, Center for Immunological and Metabolic Diseases, and Department of EndocrinologyFirst Affiliated Hospital of Xi'an Jiaotong University, Xi'an Jiaotong UniversityXi'anChina
| | - Martin Giera
- The Center for Proteomics and MetabolomicsLeiden University Medical CenterLeidenThe Netherlands
| | - Yanan Wang
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular MedicineLeiden University Medical CenterLeidenThe Netherlands
- Med‐X Institute, Center for Immunological and Metabolic Diseases, and Department of EndocrinologyFirst Affiliated Hospital of Xi'an Jiaotong University, Xi'an Jiaotong UniversityXi'anChina
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2
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Kobayashi S, Sata F, Ikeda-Araki A, Miyashita C, Goudarzi H, Iwasaki Y, Nakajima T, Kishi R. Relationships between maternal perfluoroalkyl substance levels, polymorphisms of receptor genes, and adverse birth outcomes in the Hokkaido birth cohort study, Japan. Reprod Toxicol 2021; 107:112-122. [PMID: 34896592 DOI: 10.1016/j.reprotox.2021.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/05/2021] [Accepted: 12/08/2021] [Indexed: 12/12/2022]
Abstract
We assessed the associations between perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) levels in third trimester maternal serum, the maternal genotypes of genes encoding nuclear receptors, and birth outcomes. We studied a prospective birth cohort of healthy pregnant Japanese women (n = 372) recruited in Sapporo between July 2002 and October 2005. We analyzed PFOS and PFOA levels using liquid chromatography-tandem mass spectrometry and analyzed 13 single nucleotide polymorphisms (SNPs) of proliferator-activated receptor alpha, gamma, gamma coactivator 1A, delta, constitutive androstane receptor, liver X receptor alpha, and beta (LXRB) using real-time polymerase reaction (PCR). We employed multiple linear regression models to establish the influences of log10-transformed PFOS and PFOA levels and maternal genotypes on birth size. In female infants, we identified interactions between PFOS levels, the maternal genotype of LXRB (rs1405655), and birth weight. The estimated mean changes in birth weight in response to PFOS levels, the maternal genotype LXRB (rs1405655)-TC/CC (compared to TT), and their interactions were -502.9 g (95 % confidence interval [CI] = -247.3, -758.5 g), -526.3 g (95 % CI = -200.7, -852.0 g), and 662.1 g (95 % CI = 221.0, 1,103.2 g; pint = 0.003), respectively. Interactions between PFOS levels and the maternal genotype of LXRB (rs1405655) also significantly affected birth chest circumference and the Ponderal index (pint = 0.037 and 0.005, respectively). Thus, interactions between PFOS levels and the maternal genotype of LXRB (rs1405655) affects birth sizes in female infants. We found that certain SNPs modify the effects of PFOS levels on birth size.
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Affiliation(s)
- Sumitaka Kobayashi
- Center for Environmental and Health Sciences, Hokkaido University, North-12, West-7, Kita-ku, Sapporo, 060-0812, Japan
| | - Fumihiro Sata
- Center for Environmental and Health Sciences, Hokkaido University, North-12, West-7, Kita-ku, Sapporo, 060-0812, Japan; Health Center, Chuo University, 42-8, Ichigaya-Hommura-cho, Shinjuku-ku, Tokyo, 162-8473, Japan
| | - Atsuko Ikeda-Araki
- Center for Environmental and Health Sciences, Hokkaido University, North-12, West-7, Kita-ku, Sapporo, 060-0812, Japan; Faculty of Health Sciences, Hokkaido University, North-12, West-5, Kita-ku, Sapporo, 060-0812, Japan
| | - Chihiro Miyashita
- Center for Environmental and Health Sciences, Hokkaido University, North-12, West-7, Kita-ku, Sapporo, 060-0812, Japan
| | - Houman Goudarzi
- Center for Environmental and Health Sciences, Hokkaido University, North-12, West-7, Kita-ku, Sapporo, 060-0812, Japan; Department of Respiratory Medicine, Faculty of Medicine, Hokkaido University, North-15, West-7, Kita-ku, Sapporo, 060-8638, Japan
| | - Yusuke Iwasaki
- Department of Biopharmaceutics and Analytical Science, Hoshi University, 2-4-41, Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Tamie Nakajima
- College of Life and Health Sciences, Chubu University, 1200, Matsumoto-cho, Kasugai, 487-8501, Japan
| | - Reiko Kishi
- Center for Environmental and Health Sciences, Hokkaido University, North-12, West-7, Kita-ku, Sapporo, 060-0812, Japan.
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3
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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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4
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Smooth muscle 22 alpha protein inhibits VSMC foam cell formation by supporting normal LXRα signaling, ameliorating atherosclerosis. Cell Death Dis 2021; 12:982. [PMID: 34686657 PMCID: PMC8536684 DOI: 10.1038/s41419-021-04239-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/11/2021] [Accepted: 09/29/2021] [Indexed: 12/31/2022]
Abstract
Vascular smooth muscle cells (VSMCs) are indispensable components in foam cell formation in atherosclerosis. However, the mechanism behind foam cell formation of VSMCs has not been addressed. We found a potential association between deletion of smooth muscle (SM) 22α and deregulated nuclear receptors liver X receptors (LXRs)/retinoid X receptor (RXR) signaling in mice. Here, we investigated the roles of SM22α in LXRα-modulated cholesterol homeostasis, and explore possible mechanisms underlying this process. We identified that the depletion of SM22α was a primary event driving VSMC cholesterol accumulation and the development of atherosclerosis in mice. Proteomic and lipidomic analysis validated that downregulation of SM22α was correlated with reduced expression of LXRα and ATP-binding cassette transporter (ABCA) 1 and increased cholesteryl ester in phenotypically modulated VSMCs induced by platelets-derived growth factor (PDGF)-BB. Notably, LXRα was mainly distributed in the cytoplasm rather than the nucleus in the neointimal and Sm22α-/- VSMCs. Loss of SM22α inhibited the nuclear import of LXRα and reduced ABCA1-mediated cholesterol efflux via promoting depolymerization of actin stress fibers. Affinity purification and mass spectrometry (AP-MS) analysis, co-immunoprecipitation and GST pull-down assays, confocal microscopy, and stochastic optical reconstruction microscopy (STORM) revealed that globular-actin (G-actin), monomeric actin, interacted with and retained LXRα in the cytoplasm in PDGF-BB-treated and Sm22α-/- VSMCs. This interaction blocked LXRα binding to Importin α, a karyopherin that mediates the trafficking of macromolecules across the nuclear envelope, and the resulting reduction of LXRα transcriptional activity. Increasing SM22α expression restored nuclear localization of LXRα and removed cholesterol accumulation via inducing actin polymerization, ameliorating atherosclerosis. Our findings highlight that LXRα is a mechanosensitive nuclear receptor and that the nuclear import of LXRα maintained by the SM22α-actin axis is a potential target for blockade of VSMC foam cell formation and development of anti-atherosclerosis.
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5
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Miranda-Bautista J, Rodríguez-Feo JA, Puerto M, López-Cauce B, Lara JM, González-Novo R, Martín-Hernández D, Ferreiro-Iglesias R, Bañares R, Menchén L. Liver X Receptor Exerts Anti-Inflammatory Effects in Colonic Epithelial Cells via ABCA1 and Its Expression Is Decreased in Human and Experimental Inflammatory Bowel Disease. Inflamm Bowel Dis 2021; 27:1661-1673. [PMID: 33609028 DOI: 10.1093/ibd/izab034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Liver X receptor (LXR) exerts anti-inflammatory effects in macrophages. The aim of this study was to explore the expression and function of LXR in the colonic epithelium under inflammatory conditions. METHODS The expression of LXR was explored by Western blot and immunohistochemistry in colonic biopsies from patients diagnosed with inflammatory bowel disease (IBD) and control patients. In addition, LXR and its target gene expression were analyzed in the colon from interleukin (IL)-10-deficient (IL-10-/-) and wild-type mice. Caco-2 cells were pretreated with the synthetic LXR agonist GW3965 and further challenged with IL-1β, the expression of IL-8 and chemokine (C-C motif) ligand (CCL)-28 chemokines, the activation of mitogen-activated protein (MAP) kinases, and the nuclear translocation of the p65 subunit of nuclear factor kappa B was evaluated. Glibenclamide was used as an ABCA1 antagonist. RESULTS We found that LXR expression was downregulated in colonic samples from patients with IBD and IL-10-/- mice. The nuclear positivity of LXR inversely correlated with ulcerative colitis histologic activity. Colonic IL-1β mRNA levels negatively correlated with both LXRα and LXRβ in the colon of IL-10-/- mice, where a decreased mRNA expression of the LXR target genes ABCA1 and FAS was shown. In addition, IL-1β decreased the expression of the LXR target gene ABCA1 in cultured intestinal epithelial cells. The synthetic LXR agonist GW3965 led to a decreased nuclear positivity of the p65 subunit of nuclear factor kappa B, a phosphorylation ratio of the p44-42 MAP kinase, and the expression of CCL-28 and IL-8 in IL-1β-stimulated Caco-2 cells. The pharmacological inhibition of ABCA1 increased the phosphorylation of p44-42 after GW3965 treatment and IL-1β stimulation. CONCLUSIONS The LXR-ABCA1 pathway exerts anti-inflammatory effects in intestinal epithelial cells and is impaired in the colonic mucosa of patients with IBD and IL-10-/- mice.
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Affiliation(s)
- José Miranda-Bautista
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Juan A Rodríguez-Feo
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Marta Puerto
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.,Centro de Investigación en Red de Enfermedades Hepáticas y Digestivas, Madrid, Spain
| | - Beatriz López-Cauce
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - José M Lara
- Servicio de Anatomía Patológica, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Raquel González-Novo
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - David Martín-Hernández
- Servicio de Psiquiatría del Niño y del Adolescente, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.,Centro de Investigación Biomédica en Red de Salud Mental, Instituto de Salud Carlos III, Madrid, Spain
| | | | - Rafael Bañares
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.,Centro de Investigación en Red de Enfermedades Hepáticas y Digestivas, Madrid, Spain.,Departamento de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Luis Menchén
- Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón-Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.,Centro de Investigación en Red de Enfermedades Hepáticas y Digestivas, Madrid, Spain.,Departamento de Medicina, Universidad Complutense de Madrid, Madrid, Spain
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6
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Cytoplasmic LXR expression is an independent marker of poor prognosis for patients with early stage primary breast cancer. J Cancer Res Clin Oncol 2021; 147:2535-2544. [PMID: 34085098 PMCID: PMC8310839 DOI: 10.1007/s00432-021-03670-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/20/2021] [Indexed: 02/06/2023]
Abstract
Purpose The aim of this study was to investigate the expression of liver X receptors α/β (LXR) in primary breast cancer (BC) tissues and to analyze its correlations with clinicopathological parameters including patient survival. Methods In a well-characterized cohort of 305 primary BC, subcellular distribution of LXR was evaluated by immunohistochemistry. Correlations with clinicopathological characteristics as well as with patient outcome were analyzed. Results LXR was frequently localized in both nuclei and cytoplasms of BC cells, with stronger staining in nuclei. Total and nuclear LXR expression was positively correlated with ER and PR status. Overall survival analysis demonstrated that cytoplasmic LXR was significantly correlated with poor survival and appeared as an independent marker of poor prognosis, in stage I but not in stage II–III tumors Conclusion Altogether, these data suggest that cytoplasmic LXR could be defined as a prognostic marker in early stage primary BC. Supplementary Information The online version contains supplementary material available at 10.1007/s00432-021-03670-y.
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7
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Mackay-Sim A. Hereditary Spastic Paraplegia: From Genes, Cells and Networks to Novel Pathways for Drug Discovery. Brain Sci 2021; 11:brainsci11030403. [PMID: 33810178 PMCID: PMC8004882 DOI: 10.3390/brainsci11030403] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/14/2021] [Accepted: 03/18/2021] [Indexed: 12/13/2022] Open
Abstract
Hereditary spastic paraplegia (HSP) is a diverse group of Mendelian genetic disorders affecting the upper motor neurons, specifically degeneration of their distal axons in the corticospinal tract. Currently, there are 80 genes or genomic loci (genomic regions for which the causative gene has not been identified) associated with HSP diagnosis. HSP is therefore genetically very heterogeneous. Finding treatments for the HSPs is a daunting task: a rare disease made rarer by so many causative genes and many potential mutations in those genes in individual patients. Personalized medicine through genetic correction may be possible, but impractical as a generalized treatment strategy. The ideal treatments would be small molecules that are effective for people with different causative mutations. This requires identification of disease-associated cell dysfunctions shared across genotypes despite the large number of HSP genes that suggest a wide diversity of molecular and cellular mechanisms. This review highlights the shared dysfunctional phenotypes in patient-derived cells from patients with different causative mutations and uses bioinformatic analyses of the HSP genes to identify novel cell functions as potential targets for future drug treatments for multiple genotypes.
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Affiliation(s)
- Alan Mackay-Sim
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD 4111, Australia
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8
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Wang P, Mu X, Zhao H, Li Y, Wang L, Wolfe V, Cui SN, Wang X, Peng T, Zingarelli B, Wang C, Fan GC. Administration of GDF3 Into Septic Mice Improves Survival via Enhancing LXRα-Mediated Macrophage Phagocytosis. Front Immunol 2021; 12:647070. [PMID: 33679812 PMCID: PMC7925632 DOI: 10.3389/fimmu.2021.647070] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 01/26/2021] [Indexed: 12/26/2022] Open
Abstract
The defective eradication of invading pathogens is a major cause of death in sepsis. As professional phagocytic cells, macrophages actively engulf/kill microorganisms and play essential roles in innate immune response against pathogens. Growth differentiation factor 3 (GDF3) was previously implicated as an important modulator of inflammatory response upon acute sterile injury. In this study, administration of recombinant GDF3 protein (rGDF3) either before or after CLP surgery remarkably improved mouse survival, along with significant reductions in bacterial load, plasma pro-inflammatory cytokine levels, and organ damage. Notably, our in vitro experiments revealed that rGDF3 treatment substantially promoted macrophage phagocytosis and intracellular killing of bacteria in a dose-dependent manner. Mechanistically, RNA-seq analysis results showed that CD5L, known to be regulated by liver X receptor α (LXRα), was the most significantly upregulated gene in rGDF3-treated macrophages. Furthermore, we observed that rGDF3 could promote LXRα nuclear translocation and thereby, augmented phagocytosis activity in macrophages, which was similar as LXRα agonist GW3965 did. By contrast, pre-treating macrophages with LXRα antagonist GSK2033 abolished beneficial effects of rGDF3 in macrophages. In addition, rGDF3 treatment failed to enhance bacteria uptake and killing in LXRα-knockout (KO) macrophages. Taken together, these results uncover that GDF3 may represent a novel mediator for controlling bacterial infection.
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Affiliation(s)
- Peng Wang
- Department of Critical Care Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China.,Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Xingjiang Mu
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Hongyan Zhao
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States.,Department of Critical Care Medicine, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yutian Li
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Lu Wang
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States.,Department of Critical Care Medicine, Renmin Hospital of Wuhan University, Wuhan, China
| | - Vivian Wolfe
- Division of Critical Care Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Shu-Nan Cui
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States.,Department of Anesthesiology, Beijing Cancer Hospital, Peking University School of Oncology, Beijing, China
| | - Xiaohong Wang
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Tianqing Peng
- The Centre for Critical Illness Research, Lawson Health Research Institute, London, ON, Canada
| | - Basilia Zingarelli
- Division of Critical Care Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Chunting Wang
- Department of Critical Care Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Guo-Chang Fan
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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9
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Voisin M, Gage MC, Becares N, Shrestha E, Fisher EA, Pineda-Torra I, Garabedian MJ. LXRα Phosphorylation in Cardiometabolic Disease: Insight From Mouse Models. Endocrinology 2020; 161:bqaa089. [PMID: 32496563 PMCID: PMC7324054 DOI: 10.1210/endocr/bqaa089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/29/2020] [Indexed: 01/12/2023]
Abstract
Posttranslational modifications, such as phosphorylation, are a powerful means by which the activity and function of nuclear receptors such as LXRα can be altered. However, despite the established importance of nuclear receptors in maintaining metabolic homeostasis, our understanding of how phosphorylation affects metabolic diseases is limited. The physiological consequences of LXRα phosphorylation have, until recently, been studied only in vitro or nonspecifically in animal models by pharmacologically or genetically altering the enzymes enhancing or inhibiting these modifications. Here we review recent reports on the physiological consequences of modifying LXRα phosphorylation at serine 196 (S196) in cardiometabolic disease, including nonalcoholic fatty liver disease, atherosclerosis, and obesity. A unifying theme from these studies is that LXRα S196 phosphorylation rewires the LXR-modulated transcriptome, which in turn alters physiological response to environmental signals, and that this is largely distinct from the LXR-ligand-dependent action.
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Affiliation(s)
- Maud Voisin
- Department of Microbiology, New York University School of Medicine, New York, New York, US
| | - Matthew C Gage
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Natalia Becares
- Centre of Clinical Pharmacology, Division of Medicine, University College of London, London, UK
| | - Elina Shrestha
- Department of Microbiology, New York University School of Medicine, New York, New York, US
| | - Edward A Fisher
- Department of Microbiology, New York University School of Medicine, New York, New York, US
- Department of Medicine, New York University School of Medicine, New York, New York, US
| | - Ines Pineda-Torra
- Centre of Cardiometabolic and Vascular Science, Division of Medicine, University College of London, London, UK
| | - Michael J Garabedian
- Department of Microbiology, New York University School of Medicine, New York, New York, US
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10
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Multiparametric rapid screening of neuronal process pathology for drug target identification in HSP patient-specific neurons. Sci Rep 2019; 9:9615. [PMID: 31270336 PMCID: PMC6610147 DOI: 10.1038/s41598-019-45246-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 05/29/2019] [Indexed: 11/14/2022] Open
Abstract
Axonal degeneration is a key pathology of neurodegenerative diseases, including hereditary spastic paraplegia (HSP), a disorder characterized by spasticity in the lower limbs. Treatments for HSP and other neurodegenerative diseases are mainly symptomatic. While iPSC-derived neurons are valuable for drug discovery and target identification, these applications require robust differentiation paradigms and rapid phenotypic read-outs ranging between hours and a few days. Using spastic paraplegia type 4 (SPG4, the most frequent HSP subtype) as an exemplar, we here present three rapid phenotypic assays for uncovering neuronal process pathologies in iPSC-derived glutamatergic cortical neurons. Specifically, these assays detected a 51% reduction in neurite outgrowth and a 60% increase in growth cone area already 24 hours after plating; axonal swellings, a hallmark of HSP pathology, was discernible after only 5 days. Remarkably, the identified phenotypes were neuron subtype-specific and not detectable in SPG4-derived GABAergic forebrain neurons. We transferred all three phenotypic assays to a 96-well setup, applied small molecules and found that a liver X receptor (LXR) agonist rescued all three phenotypes in HSP neurons, providing a potential drug target for HSP treatment. We expect this multiparametric and rapid phenotyping approach to accelerate development of therapeutic compounds for HSP and other neurodegenerative diseases.
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11
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Petrov AM, Pikuleva IA. Cholesterol 24-Hydroxylation by CYP46A1: Benefits of Modulation for Brain Diseases. Neurotherapeutics 2019; 16:635-648. [PMID: 31001737 PMCID: PMC6694357 DOI: 10.1007/s13311-019-00731-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cholesterol 24-hydroxylation is the major mechanism for cholesterol removal from the brain and the reaction catalyzed by cytochrome P450 46A1 (CYP46A1), a CNS-specific enzyme. This review describes CYP46A1 in the context of cholesterol homeostasis in the brain and summarizes available experimental data on CYP46A1 association with different neurologic diseases, including the mechanisms by which changes in the CYP46A1 activity in the brain could be beneficial for these diseases. The modulation of CYP46A1 activity by genetic and pharmacologic means is also presented along with a brief synopsis of the two clinical trials that evaluate CYP46A1 as a therapeutic target for Alzheimer's disease as well as Dravet and Lennox-Gastaut syndromes.
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Affiliation(s)
- Alexey M Petrov
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, 2085 Adelbert Rd., Room 303, Cleveland, OH, 44106, USA
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, 2085 Adelbert Rd., Room 303, Cleveland, OH, 44106, USA.
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12
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Myat AB, Ogawa T, Kadota-Watanabe C, Moriyama K. Nuclear import of transcriptional corepressor BCOR occurs through interaction with karyopherin α expressed in human periodontal ligament. Biochem Biophys Res Commun 2018; 507:67-73. [PMID: 30396568 DOI: 10.1016/j.bbrc.2018.10.158] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 10/25/2018] [Indexed: 10/27/2022]
Abstract
Mutations in the gene encoding BCL-6 corepressor (BCOR) are responsible for oculofaciocardiodental (OFCD) syndrome, which is a rare X-linked dominant disorder characterized by radiculomegaly of permanent teeth as the most typical symptom. To function as a transcriptional corepressor, BCOR needs to enter the nucleus; however, the molecular pathway for its nuclear translocation during dental root formation remains unclear. The purpose of this study was to determine the mechanism underlying BCOR transport into the nucleus. Our results showed that human periodontal ligament (PDL) cells expressed karyopherin α (KPNA)2, KPNA4, and KPNA6 belonging to a family of nuclear import proteins, which interacted with BCOR in the immunoprecipitation assay. Site-directed mutagenesis targeting the two nuclear localization signals (NLSs) within BCOR reduced its nuclear translocation; however, co-expression of KPNA2, KPNA4, or KPNA6 with BCOR carrying a previously described mutation which eliminated one of the two NLSs significantly increased nuclear accumulation of the mutant BCOR, indicating participation of KPNA in BCOR nuclear translocation. Comparative expression profiling of PDL cells isolated from normal and OFCD patients revealed significant downregulation of SMAD4, GLI1, and nuclear factor 1-C (NFIC) mRNA expression, suggesting that BCOR mutations cause hyperactive root formation in OFCD syndrome by inhibiting SMAD4-Hedgehog-NFIC signaling implicated in dental root development. Our study contributes to understanding of the mechanisms providing nuclear import of BCOR during root formation.
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Affiliation(s)
- Aung Bhone Myat
- Department of Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
| | - Takuya Ogawa
- Department of Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
| | - Chiho Kadota-Watanabe
- Department of Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
| | - Keiji Moriyama
- Department of Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
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13
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Wang Q, Feng F, Wang J, Ren M, Shi Z, Mao X, Zhang H, Ju X. Liver X receptor activation reduces gastric cancer cell proliferation by suppressing Wnt signalling via LXRβ relocalization. J Cell Mol Med 2018; 23:789-797. [PMID: 30338932 PMCID: PMC6349166 DOI: 10.1111/jcmm.13974] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 09/28/2018] [Indexed: 12/12/2022] Open
Abstract
Liver X receptors (LXRs) are involved in various diseases associated with lipid disorders, and in regulating cancer cell proliferation. However, the underlying molecular mechanisms, especially those in gastric cancer (GC) remain to be clarified. In this study, immunohistochemistry analysis revealed that LXRβ was mainly expressed in GC tissue, with less expression in adjacent normal tissues. The LXRβ agonist T0901317 efficiently suppressed the proliferation and colony formation of various GC cell lines. We further showed that LXRβ translocated from the cytoplasm to the nucleus when activated by T0901317. LXRβ nuclear localization suppressed the activation of Wnt signalling and decreased the expression of target genes such as MYC, BMP4, and MMP7 through binding to their promoters. Moreover, we demonstrated that the LXR agonist efficiently suppressed GC tumour growth in a nude mouse xenograft model. Taken together, these results revealed that LXRβ agonist inhibited GC cells proliferation by suppressing Wnt signalling via LXRβ relocalization. The results strongly suggest that LXRβ could be a promising target in GC therapy.
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Affiliation(s)
- Qiang Wang
- Institute of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Fan Feng
- The Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Jiayou Wang
- Institute of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Meijia Ren
- Institute of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Zhonggang Shi
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Xiang Mao
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Heng Zhang
- Department of General Surgery, Nanjing Lishui District People's Hospital, Zhongda Hospital Lishui Branch, Southeast University, Nanjing, China
| | - Xiaoli Ju
- School of Medicine, Jiangsu University, Zhenjiang, China
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14
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Mathew SP, Thakur K, Kumar S, Yende AS, Singh SK, Dash AK, Tyagi RK. A Comprehensive Analysis and Prediction of Sub-Cellular Localization of Human Nuclear Receptors. NUCLEAR RECEPTOR RESEARCH 2018. [DOI: 10.11131/2018/101324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Lin HC, Lii CK, Chen HC, Lin AH, Yang YC, Chen HW. Andrographolide Inhibits Oxidized LDL-Induced Cholesterol Accumulation and Foam Cell Formation in Macrophages. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2018; 46:87-106. [PMID: 29298513 DOI: 10.1142/s0192415x18500052] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
oxLDL is involved in the pathogenesis of atherosclerotic lesions through cholesterol accumulation in macrophage foam cells. Andrographolide, the bioactive component of Andrographis paniculata, possesses several biological activities such as anti-inflammatory, anti-oxidant, and anticancer functions. Scavenger receptors (SRs), including class A SR (SR-A) and CD36, are responsible for the internalization of oxLDL. In contrast, receptors for reverse cholesterol transport, including ABCA1 and ABCG1, mediate the efflux of cholesterol from macrophage foam cells. Transcription factor liver X receptor [Formula: see text] (LXR[Formula: see text] plays a key role in lipid metabolism and inflammation as well as in the regulation of ABCA1 and ABCG1 expression. Because of the contribution of inflammation to macrophage foam cell formation and the potent anti-inflammatory activity of andrographolide, we hypothesized that andrographolide might inhibit oxLDL-induced macrophage foam cell formation. The results showed that andrographolide reduced oxLDL-induced lipid accumulation in macrophage foam cells. Andrographolide decreased the mRNA and protein expression of CD36 by inducing the degradation of CD36 mRNA; however, andrographolide had no effect on SR-A expression. In contrast, andrographolide increased the mRNA and protein expression of ABCA1 and ABCG1, which were dependent on LXR[Formula: see text]. Andrographolide enhanced LXR[Formula: see text] nuclear translocation and DNA binding activity. Treatment with the LXR[Formula: see text] antagonist GGPP and transfection with LXR[Formula: see text] siRNA reversed the ability of andrographolide to stimulate ABCA1 and ABCG1 protein expression. In conclusion, inhibition of CD36-mediated oxLDL uptake and induction of ABCA1- and ABCG1-dependent cholesterol efflux are two working mechanisms by which andrographolide inhibits macrophage foam cell formation, which suggests that andrographolide could be a potential candidate to prevent atherosclerosis.
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Affiliation(s)
- Hung-Chih Lin
- Division of Neonatology, College of Medicine and Department of Pediatrics, Children’s Hospital of China Medical, University and China Medical University Hospital, Taichung, Taiwan
| | - Chong-Kuei Lii
- Department of Nutrition, China Medical University, Taichung, Taiwan
- Department of Food Nutrition and Health Biotechnology, Asia University, Taichung, Taiwan
| | - Hui-Chun Chen
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - Ai-Hsuan Lin
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - Ya-Chen Yang
- Department of Food Nutrition and Health Biotechnology, Asia University, Taichung, Taiwan
| | - Haw-Wen Chen
- Department of Nutrition, China Medical University, Taichung, Taiwan
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16
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Dash AK, Yende AS, Jaiswal B, Tyagi RK. Heterodimerization of Retinoid X Receptor with Xenobiotic Receptor partners occurs in the cytoplasmic compartment: Mechanistic insights of events in living cells. Exp Cell Res 2017; 360:337-346. [DOI: 10.1016/j.yexcr.2017.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/12/2017] [Accepted: 09/15/2017] [Indexed: 01/30/2023]
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17
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Pillaiyar T, Manickam M, Jung SH. Recent development of signaling pathways inhibitors of melanogenesis. Cell Signal 2017; 40:99-115. [PMID: 28911859 DOI: 10.1016/j.cellsig.2017.09.004] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 09/10/2017] [Accepted: 09/10/2017] [Indexed: 02/08/2023]
Abstract
Human skin, eye and hair color rely on the production of melanin, depending on its quantity, quality, and distribution, Melanin plays a monumental role in protecting the skin against the harmful effect of ultraviolet radiation and oxidative stress from various environmental pollutants. However, an excessive production of melanin causes serious dermatological problems such as freckles, solar lentigo (age spots), melasma, as well as cancer. Hence, the regulation of melanin production is important for controlling the hyper-pigmentation. Melanogenesis, a biosynthetic pathway to produce melanin pigment in melanocyte, involves a series of intricate enzymatic and chemical catalyzed reactions. Several extrinsic factors include ultraviolet radiation and chemical drugs, and intrinsic factors include molecules secreted by surrounding keratinocytes or melanocytes, and fibroblasts, all of which regulate melanogenesis. This article reviews recent advances in the development of melanogenesis inhibitors that directly/indirectly target melanogenesis-related signaling pathways. Efforts have been made to provide a description of the mechanism of action of inhibitors on various melanogenesis signaling pathways.
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Affiliation(s)
- Thanigaimalai Pillaiyar
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany.
| | - Manoj Manickam
- College of Pharmacy and Institute of Drug Research and Development, Chungnam National, University, Daejeon 34134, Republic of Korea
| | - Sang-Hun Jung
- College of Pharmacy and Institute of Drug Research and Development, Chungnam National, University, Daejeon 34134, Republic of Korea
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18
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Lee HJ, Ryu JM, Jung YH, Lee SJ, Kim JY, Lee SH, Hwang IK, Seong JK, Han HJ. High glucose upregulates BACE1-mediated Aβ production through ROS-dependent HIF-1α and LXRα/ABCA1-regulated lipid raft reorganization in SK-N-MC cells. Sci Rep 2016; 6:36746. [PMID: 27829662 PMCID: PMC5103190 DOI: 10.1038/srep36746] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 10/20/2016] [Indexed: 01/07/2023] Open
Abstract
There is an accumulation of evidence indicating that the risk of Alzheimer’s disease is associated with diabetes mellitus, an indicator of high glucose concentrations in blood plasma. This study investigated the effect of high glucose on BACE1 expression and amyloidogenesis in vivo, and we present details of the mechanism associated with those effects. Our results, using ZLC and ZDF rat models, showed that ZDF rats have high levels of amyloid-beta (Aβ), phosphorylated tau, BACE1, and APP-C99. In vitro result with mouse hippocampal neuron and SK-N-MC, high glucose stimulated Aβ secretion and apoptosis in a dose-dependent manner. In addition, high glucose increased BACE1 and APP-C99 expressions, which were reversed by a reactive oxygen species (ROS) scavenger. Indeed, high glucose increased intracellular ROS levels and HIF-1α expression, associated with regulation of BACE1 and Liver X Receptor α (LXRα). In addition, high glucose induced ATP-binding cassette transporter A1 (ABCA1) down-regulation, was associated with LXR-induced lipid raft reorganization and BACE1 localization on the lipid raft. Furthermore, silencing of BACE1 expression was shown to regulate Aβ secretion and apoptosis of SK-N-MC. In conclusion, high glucose upregulates BACE1 expression and activity through HIF-1α and LXRα/ABCA1-regulated lipid raft reorganization, leading to Aβ production and apoptosis of SK-N-MC.
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Affiliation(s)
- Hyun Jik Lee
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science and BK21 PLUS Program for Creative Veterinary Science Research Center, Seoul National University, Seoul 08826, Korea
| | - Jung Min Ryu
- Department of Veterinary Physiology, College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
| | - Young Hyun Jung
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science and BK21 PLUS Program for Creative Veterinary Science Research Center, Seoul National University, Seoul 08826, Korea
| | - Sei-Jung Lee
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science and BK21 PLUS Program for Creative Veterinary Science Research Center, Seoul National University, Seoul 08826, Korea
| | - Jeong Yeon Kim
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science and BK21 PLUS Program for Creative Veterinary Science Research Center, Seoul National University, Seoul 08826, Korea
| | - Sang Hun Lee
- Medical Science Research Institute, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea.,Department of Biochemistry, Soonchunhyang University College of Medicine, Cheonan, 330-930, Republic of Korea
| | - In Koo Hwang
- BK21 PLUS Program for Creative Veterinary Science Research, and Research Institute for Veterinary Science; Seoul National University and Korea Mouse Phenotyping Center (KMPC), Seoul, Korea.,Department of Anatomy and Cell Biology; Korea Mouse Phenotyping Center (KMPC); College of Veterinary Medicine; Seoul National University, Seoul, Korea
| | - Je Kyung Seong
- BK21 PLUS Program for Creative Veterinary Science Research, and Research Institute for Veterinary Science; Seoul National University and Korea Mouse Phenotyping Center (KMPC), Seoul, Korea.,Department of Anatomy and Cell Biology; Korea Mouse Phenotyping Center (KMPC); College of Veterinary Medicine; Seoul National University, Seoul, Korea
| | - Ho Jae Han
- Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Science and BK21 PLUS Program for Creative Veterinary Science Research Center, Seoul National University, Seoul 08826, Korea
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19
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Liver X receptor ligand cytotoxicity in colon cancer cells and not in normal colon epithelial cells depends on LXRβ subcellular localization. Oncotarget 2016; 6:26651-62. [PMID: 26450852 PMCID: PMC4694942 DOI: 10.18632/oncotarget.5791] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/08/2015] [Indexed: 01/22/2023] Open
Abstract
Increasing evidence indicates that Liver X Receptors (LXRs) have some anticancer properties. We recently demonstrated that LXR ligands induce colon cancer cell pyroptosis through an LXRβ-dependent pathway. In the present study, we showed that human colon cancer cell lines presented differential cytoplasmic localizations of LXRβ. This localization correlated with caspase-1 activation and cell death induction under treatment with LXR ligand. The association of LXRβ with the truncated form of RXRα (t-RXRα) was responsible for the sequestration of LXRβ in the cytoplasm in colon cancer cells. Moreover t-RXRα was not expressed in normal colon epithelial cells. These cells presented a predominantly nuclear localization of LXRβ and were resistant to LXR ligand cytotoxicity. Our results showed that predominant cytoplasmic localization of LXRβ, which occurs in colon cancer cells but not in normal colon epithelial cells, allowed LXR ligand-induced pyroptosis. This study strengthens the hypothesis that LXRβ could be a promising target in cancer therapy.
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20
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Sun Y, Xian L, Xing H, Yu J, Yang Z, Yang T, Yang L, Ding P. Factors influencing the nuclear targeting ability of nuclear localization signals. J Drug Target 2016; 24:927-933. [DOI: 10.1080/1061186x.2016.1184273] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Kim MO, Park YS, Nho YH, Yun SK, Kim Y, Jung E, Paik JK, Kim M, Cho IH, Lee J. Emodin isolated from Polygoni Multiflori Ramulus inhibits melanogenesis through the liver X receptor-mediated pathway. Chem Biol Interact 2016; 250:78-84. [PMID: 26972667 DOI: 10.1016/j.cbi.2016.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/17/2016] [Accepted: 03/08/2016] [Indexed: 12/22/2022]
Abstract
Melanogenesis is a physiological process that results in the synthesis of melanin pigments, which play a crucial protective role against skin photocarcinogenesis. We investigated the effects of a Polygoni Multiflori Ramulus extract on melanogenesis and isolated emodin from Polygoni Multiflori as an active compound. In addition, the possible mechanisms of action were examined. We found that emodin inhibited both melanin content and tyrosinase activity concentration and time dependently. Tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 mRNA levels decreased following emodin treatment. However, while the mRNA levels of microphthalmia-associated transcription factor (MITF) were not affected by emodin, emodin reduced MITF protein levels. Furthermore, expression of the liver X-receptor (LXR) α gene, but not the LXR β gene was upregulated by emodin. Moreover, emodin regulated melanogenesis by promoting degradation of the MITF protein by upregulating the LXR α gene. The emodin effects on MITF was found to be mediated by phosphorylation of p42/44 MAPK. Taken together, these findings indicate that the inhibition of melanogenesis by emodin occurs through reduced MITF protein expression, which is mediated by upregulation of the LXR α gene and suggest that emodin may be useful as a hyperpigmentation inhibitor.
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Affiliation(s)
- Mi Ok Kim
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon City, 164-19 Gyunggi Do, Republic of Korea
| | - Yong Seek Park
- Department of Microbiology, School of Medicine, Kyung Hee University, 024-53 Seoul, Republic of Korea
| | - Youn Hwa Nho
- COSMAX R&I Center, COSMAX Inc., Seongnam City, 134-86 Gyunggi Do, Republic of Korea
| | - Seok Kyun Yun
- COSMAX R&I Center, COSMAX Inc., Seongnam City, 134-86 Gyunggi Do, Republic of Korea
| | - Youngsoo Kim
- Biospectrum Life Science Institute, Seongnam City, 132-16 Gyunggi Do, Republic of Korea
| | - Eunsun Jung
- Biospectrum Life Science Institute, Seongnam City, 132-16 Gyunggi Do, Republic of Korea
| | - Jean Kyung Paik
- Department of Food and Nutrition, College of Health Industry, Eulji University, Seongnam City, 131-35 Gyunggi Do, Republic of Korea
| | - Minhee Kim
- Department of Physical Therapy, College of Health Science, Eulji University, Seongnam City, 131-35 Gyunggi Do, Republic of Korea
| | - Il-Hoon Cho
- Department of Biomedical Laboratory Science, College of Health Science, Eulji University, Seongnam City, 131-35 Gyunggi Do, Republic of Korea.
| | - Jongsung Lee
- Department of Genetic Engineering, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon City, 164-19 Gyunggi Do, Republic of Korea.
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22
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Tan YA, Xiao LB, Zhao J, Xiao YF, Sun Y, Bai LX. Ecdysone receptor isoform-B mediates soluble trehalase expression to regulate growth and development in the mirid bug, Apolygus lucorum (Meyer-Dür). INSECT MOLECULAR BIOLOGY 2015; 24:611-623. [PMID: 26335337 DOI: 10.1111/imb.12185] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ecdysone receptor (EcR) is the hormonal receptor of ecdysteroids and strictly regulates growth and development in insects. However, the action mechanism of EcR is not very clear. In this study, the cDNA of EcR isoform-B was cloned from Apolygus lucorum (AlEcR-B) and its expression profile was investigated. We reduced AlEcR-B mRNA expression using systemic RNA interference in vivo, and obtained knockdown specimens. Examination of these specimens indicated that AlEcR-B is required for nymphal survival, and that reduced expression is associated with longer development time and lower nymphal weight. To investigate the underlying molecular mechanism of the observed suppression effects, we selected trehalase for a detailed study. Transcript encoding soluble trehalase (AlTre-1) was up-regulated by 20-hydroxyecdysone and in agreement with the mRNA expression of AlEcR-B. The expression profile of AlTre-1, soluble trehalase activity and translated protein level in the midgut of surviving nymphs were down-regulated, compared with controls, after the knockdown expression of AlEcR-B. By contrast, membrane-bound trehalase activity, the related gene expression and translated protein level remained at their initial levels. However, trehalose content significantly increased and the glucose content significantly decreased under the same conditions. We propose that AlEcR-B controls normal carbohydrate metabolism by mediating the expression of AlTre-1 to regulate the growth and development in A. lucorum, which provide an extended information into the functions of AlEcR-B.
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Affiliation(s)
- Y-A Tan
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - L-B Xiao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - J Zhao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Y-F Xiao
- Entomology and Nematology, Mid-Florida Research and Education Center, University of Florida, FL, USA
| | - Y Sun
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - L-X Bai
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
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23
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Surapornsawasd T, Ogawa T, Moriyama K. Identification of nuclear localization signals within the human BCOR protein. FEBS Lett 2015; 589:3313-20. [PMID: 26054978 DOI: 10.1016/j.febslet.2015.05.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/12/2015] [Indexed: 11/30/2022]
Abstract
Mutations in the BCL-6 corepressor (BCOR) gene, which encodes a transcriptional corepressor, were described to cause oculofaciocardiodental syndrome (MIM 300166). The purpose of this study was to localize the classical nuclear localization signals (NLSs) of the BCOR using reported human BCOR mutations with comparable phenotypes. The genotype-phenotype correlation among the mutations could not be clearly explained; however, the classical NLSs were identified at two possible sites; RVDRKRKVSGD at aa1131-1141 (NLS1) and LKAKRRRVSK at aa1158-1167 (NLS2). In addition, according to our results, NLS2 displayed a more efficient nuclear import function than NLS1.
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Affiliation(s)
- Thunyaporn Surapornsawasd
- Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
| | - Takuya Ogawa
- Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan; Hard Tissue Genome Research Center, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
| | - Keiji Moriyama
- Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan; Hard Tissue Genome Research Center, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
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24
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Candelaria NR, Addanki S, Zheng J, Nguyen-Vu T, Karaboga H, Dey P, Gabbi C, Vedin LL, Liu K, Wu W, Jonsson PK, Lin JZ, Su F, Bollu LR, Hodges SE, McElhany AL, Issazadeh MA, Fisher WE, Ittmann MM, Steffensen KR, Gustafsson JÅ, Lin CY. Antiproliferative effects and mechanisms of liver X receptor ligands in pancreatic ductal adenocarcinoma cells. PLoS One 2014; 9:e106289. [PMID: 25184494 PMCID: PMC4153644 DOI: 10.1371/journal.pone.0106289] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/30/2014] [Indexed: 11/18/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is difficult to detect early and is often resistant to standard chemotherapeutic options, contributing to extremely poor disease outcomes. Members of the nuclear receptor superfamily carry out essential biological functions such as hormone signaling and are successfully targeted in the treatment of endocrine-related malignancies. Liver X receptors (LXRs) are nuclear receptors that regulate cholesterol homeostasis, lipid metabolism, and inflammation, and LXR agonists have been developed to regulate LXR function in these processes. Intriguingly, these compounds also exhibit antiproliferative activity in diverse types of cancer cells. In this study, LXR agonist treatments disrupted proliferation, cell-cycle progression, and colony-formation of PDAC cells. At the molecular level, treatments downregulated expression of proteins involved in cell cycle progression and growth factor signaling. Microarray experiments further revealed changes in expression profiles of multiple gene networks involved in biological processes and pathways essential for cell growth and proliferation following LXR activation. These results establish the antiproliferative effects of LXR agonists and potential mechanisms of action in PDAC cells and provide evidence for their potential application in the prevention and treatment of PDAC.
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Affiliation(s)
- Nicholes R. Candelaria
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Sridevi Addanki
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Jine Zheng
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Trang Nguyen-Vu
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Husna Karaboga
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Prasenjit Dey
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Chiara Gabbi
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Lise-Lotte Vedin
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Ka Liu
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Wanfu Wu
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Philip K. Jonsson
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Jean Z. Lin
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Center for Diabetes Research, Houston Methodist Research Institute, Houston, Texas, United States of America
| | - Fei Su
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Lakshmi Reddy Bollu
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Sally E. Hodges
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, United States of America
- The Elkins Pancreas Center at Baylor College of Medicine, Houston, Texas, United States of America
| | - Amy L. McElhany
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, United States of America
- The Elkins Pancreas Center at Baylor College of Medicine, Houston, Texas, United States of America
| | - Mehdi A. Issazadeh
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, United States of America
- The Elkins Pancreas Center at Baylor College of Medicine, Houston, Texas, United States of America
| | - William E. Fisher
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas, United States of America
- The Elkins Pancreas Center at Baylor College of Medicine, Houston, Texas, United States of America
| | - Michael M. Ittmann
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Knut R. Steffensen
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Jan-Åke Gustafsson
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department of Biosciences and Nutrition at NOVUM, Karolinska Institutet, Huddinge, Sweden
| | - Chin-Yo Lin
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- * E-mail:
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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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Ma AZS, Song ZY, Zhang Q. Cholesterol efflux is LXRα isoform-dependent in human macrophages. BMC Cardiovasc Disord 2014; 14:80. [PMID: 24996838 PMCID: PMC4107624 DOI: 10.1186/1471-2261-14-80] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 06/26/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The nuclear receptor liver X receptor (LXR) has two isoforms: LXRα and LXRβ. LXR activation promotes cholesterol efflux in macrophages, but the relative importance of each LXR isoform in mediating cholesterol efflux remains elusive. METHODS We evaluated the ability of different doses of LXRs agonist T0901317 to affect cholesterol efflux in human macrophages and its relationship with mRNA and protein levels of several well-characterized proteins involved in cholesterol efflux, including ABCA1, ABCG1, SR-BI, LXRβ and LXRα, using quantitative real-time PCR, Western blotting, and siRNA techniques. RESULTS Here we show that LXRα rather than LXRβ sustains baseline cholesterol efflux in human blood-derived macrophages. Treatment of human macrophages with a non-isoform-specific LXR agonist T0901317 substantially increased HDL- and apoA-I-mediated cholesterol efflux, which was associated with increased mRNA and protein expression levels of ABCA1, ABCG1, SR-BI, LXRα and LXRβ. The siRNA- mediated silencing of LXRα, but not LXRβ significantly reduced the protein levels of ABCA1,ABCG1, and SR-BI as wellas HDL- and ApoA1-mediated cholesterol in human macrophages. CONCLUSIONS These findings imply that LXRα- rather than LXRβ- specific agonists may promote reverse cholesterol transport in humans.
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Affiliation(s)
| | - Zhi Yuan Song
- Department of Cardiology, Southwest Hospital, The Third Military Medical University, Chongqing, China.
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27
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Schaffer S, Tandon R, Zipse H, Siess W, Schmidt A, Jamasbi J, Karshovska E, Steglich W, Lorenz R. Stereo specific platelet inhibition by the natural LXR agonist 22(R)-OH-cholesterol and its fluorescence labelling with preserved bioactivity and chiral handling in macrophages. Biochem Pharmacol 2013; 86:279-85. [DOI: 10.1016/j.bcp.2013.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/26/2013] [Accepted: 04/30/2013] [Indexed: 01/15/2023]
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Liver X receptor activation inhibits melanogenesis through the acceleration of ERK-mediated MITF degradation. J Invest Dermatol 2012; 133:1063-71. [PMID: 23223141 DOI: 10.1038/jid.2012.409] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Liver X receptors (LXRs) are nuclear receptors that act as ligand-activated transcription factors regulating lipid metabolism and inflammation. In the skin, activation of LXRs stimulates differentiation of keratinocytes and augments lipid synthesis in sebocytes. However, the function of LXRs in melanocytes remains largely unknown. We investigated whether LXR activation would affect melanogenesis. In human primary melanocytes, MNT-1, and B16 melanoma cells, TO901317, a synthetic LXR ligand, inhibited melanogenesis. Small interfering RNA (siRNA) experiments revealed the dominant role of LXRβ in TO901317-mediated antimelanogenesis. Enzymatic activities of tyrosinase were unaffected, but the expression of tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2 was suppressed by TO901317. Expressions of microphthalmia-associated transcription factor (MITF), a master transcriptional regulator of melanogenesis, and cAMP-responsive element-binding activation were not affected. It is noteworthy that the degradation of MITF was accelerated by TO901317. Extracellular signal-regulated kinase (ERK) contributed to TO901317-induced antimelanogenesis, which was evidenced by recovery of melanogenesis with ERK inhibitor. Other LXR ligands, 22(R)-hydroxycholesterol (22(R)HC) and GW3965, also activated ERK and suppressed melanogenesis. The intermediary role of Ras was confirmed in TO901317-induced ERK phosphorylation. Finally, antimelanogenic effects of TO901317 were confirmed in vivo in UVB-tanning model in brown guinea pigs, providing a previously unreported line of evidence that LXRs may be important targets for antimelanogenesis.
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29
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Tang B, Dong W, Liang P, Zhou X, Gao X. Cloning, ligand-binding, and temporal expression of ecdysteroid receptors in the diamondback moth, Plutella xylostella. BMC Mol Biol 2012; 13:32. [PMID: 23078528 PMCID: PMC3568735 DOI: 10.1186/1471-2199-13-32] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 10/11/2012] [Indexed: 01/17/2023] Open
Abstract
Background The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a devastating pest of cruciferous crops worldwide, and has developed resistance to a wide range of insecticides, including diacylhydrazine-based ecdysone agonists, a highly selective group of molt-accelerating biopesticides targeting the ecdysone receptors. Result In this study, we cloned and characterized the ecdysone receptors from P. xylostella, including the two isoforms of EcR and a USP. Sequence comparison and phylogenetic analysis showed striking conservations among insect ecdysone receptors, especially between P. xylostella and other lepidopterans. The binding affinity of ecdysteroids to in vitro-translated receptor proteins indicated that PxEcRB isoform bound specifically to ponasterone A, and the binding affinity was enhanced by co-incubation with PxUSP (Kd =3.0±1.7 nM). In contrast, PxEcRA did not bind to ponasterone A, even in the presence of PxUSP. The expression of PxEcRB were consistently higher than that of PxEcRA across each and every developmental stage, while the pattern of PxUSP expression is more or less ubiquitous. Conclusions Target site insensitivity, in which the altered binding of insecticides (ecdysone agonists) to their targets (ecdysone receptors) leads to an adaptive response (resistance), is one of the underlying mechanisms of diacylhydrazine resistance. Given the distinct differences at expression level and the ligand-binding capacity, we hypothesis that PxEcRB is the ecdysone receptor that controls the remodeling events during metamorphosis. More importantly, PxEcRB is the potential target site which is modified in the ecdysone agonist-resistant P. xylostella.
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Affiliation(s)
- Baozhen Tang
- Department of Entomology, China Agricultural University, Beijing, China
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30
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Mavinakere MS, Powers JM, Subramanian KS, Roggero VR, Allison LA. Multiple novel signals mediate thyroid hormone receptor nuclear import and export. J Biol Chem 2012; 287:31280-97. [PMID: 22815488 PMCID: PMC3438959 DOI: 10.1074/jbc.m112.397745] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Thyroid hormone receptor (TR) is a member of the nuclear receptor superfamily that shuttles between the cytosol and nucleus. The fine balance between nuclear import and export of TR has emerged as a critical control point for modulating thyroid hormone-responsive gene expression; however, sequence motifs of TR that mediate shuttling are not fully defined. Here, we characterized multiple signals that direct TR shuttling. Along with the known nuclear localization signal in the hinge domain, we identified a novel nuclear localization signal in the A/B domain of thyroid hormone receptor α1 that is absent in thyroid hormone receptor β1 and inactive in the oncoprotein v-ErbA. Our prior studies showed that thyroid hormone receptor α1 exits the nucleus through two pathways, one dependent on the export factor CRM1 and the other CRM1-independent. Here, we identified three novel CRM1-independent nuclear export signal (NES) motifs in the ligand-binding domain as follows: a highly conserved NES in helix 12 (NES-H12) and two additional NES sequences spanning helix 3 and helix 6, respectively. Mutations predicted to disrupt the α-helical structure resulted in a significant decrease in NES-H12 activity. The high degree of conservation of helix 12 suggests that this region may function as a key NES in other nuclear receptors. Furthermore, our mutagenesis studies on NES-H12 suggest that altered shuttling of thyroid hormone receptor β1 may be a contributing factor in resistance to thyroid hormone syndrome. Taken together, our findings provide a detailed mechanistic understanding of the multiple signals that work together to regulate TR shuttling and transcriptional activity, and they provide important insights into nuclear receptor function in general.
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Affiliation(s)
- Manohara S Mavinakere
- Department of Biology, College of William and Mary, Williamsburg, Virginia 23187, USA
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Vo T, Hardy DB. Molecular mechanisms underlying the fetal programming of adult disease. J Cell Commun Signal 2012; 6:139-53. [PMID: 22623025 DOI: 10.1007/s12079-012-0165-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 05/02/2012] [Indexed: 12/30/2022] Open
Abstract
Adverse events in utero can be critical in determining quality of life and overall health. It is estimated that up to 50 % of metabolic syndrome diseases can be linked to an adverse fetal environment. However, the mechanisms linking impaired fetal development to these adult diseases remain elusive. This review uncovers some of the molecular mechanisms underlying how normal physiology may be impaired in fetal and postnatal life due to maternal insults in pregnancy. By understanding the mechanisms, which include epigenetic, transcriptional, endoplasmic reticulum (ER) stress, and reactive oxygen species (ROS), we also highlight how intervention in fetal and neonatal life may be able to prevent these diseases long-term.
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Affiliation(s)
- Thin Vo
- The Department of Physiology & Pharmacology, University of Western Ontario, London, Ontario, Canada, N6A 5C1
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Marwarha G, Rhen T, Schommer T, Ghribi O. The oxysterol 27-hydroxycholesterol regulates α-synuclein and tyrosine hydroxylase expression levels in human neuroblastoma cells through modulation of liver X receptors and estrogen receptors--relevance to Parkinson's disease. J Neurochem 2011; 119:1119-36. [PMID: 21951066 PMCID: PMC3217121 DOI: 10.1111/j.1471-4159.2011.07497.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Loss of dopaminergic neurons and α-synuclein accumulation are the two major pathological hallmarks of Parkinson's disease. Currently, the mechanisms governing depletion of dopamine content and α-synuclein accumulation are not well understood. We showed that the oxysterol 27-hydroxycholesterol (27-OHC) reduces the expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis, and increases α-synuclein levels in SH-SY5Y cells. However, the cellular mechanisms involved in 27-OHC effects were not elucidated. In this study, we demonstrate that 27-OHC regulates TH and α-synuclein expression levels through the estrogen receptors (ER) and liver X receptors (LXR). We specifically show that inhibition of ERβ mediates 27-OHC-induced decrease in TH expression, an effect reversed by the ER agonist estradiol. We also show that 27-OHC and the LXR agonist GW3965 increase α-synuclein while the LXR antagonist 5α-6α-epoxycholesterol-3-sulfate significantly attenuated the 27-OHC-induced increase in α-synuclein expression. We further demonstrate that LXRβ positively regulates α-synuclein expression and 27-OHC increases LXRβ-mediated α-synuclein transcription. Our results demonstrate the involvement of two distinct pathways that are involved in the 27-OHC regulation of TH and α-synuclein levels. Concomitant activation of ERβ and inhibition of LXRβ prevent 27-OHC effects and may therefore reduce the progression of Parkinson's disease by precluding TH reduction and α-synuclein accumulation.
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Affiliation(s)
- Gurdeep Marwarha
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202
| | - Turk Rhen
- Department of Biology, University of North Dakota, Grand Forks, North Dakota, 58202
| | | | - Othman Ghribi
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202
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Hozoji-Inada M, Munehira Y, Nagao K, Kioka N, Ueda K. Liver X receptor beta (LXRbeta) interacts directly with ATP-binding cassette A1 (ABCA1) to promote high density lipoprotein formation during acute cholesterol accumulation. J Biol Chem 2011; 286:20117-24. [PMID: 21507939 DOI: 10.1074/jbc.m111.235846] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cells have evolved multiple mechanisms for maintaining cholesterol homeostasis, and, among these, ATP-binding cassette protein A1 (ABCA1)-mediated cholesterol efflux is highly regulated at the transcriptional level through the activity of the nuclear receptor liver X receptor (LXR). Here, we show that in addition to its well defined role in transcription, LXRβ directly binds to the C-terminal region ((2247)LTSFL(2251)) of ABCA1 to mediate its post-translational regulation. In the absence of cholesterol accumulation in the macrophage-like cell line THP-1, the ABCA1-LXRβ complex stably localizes to the plasma membrane, but apolipoprotein A-I (apoA-I) binding or cholesterol efflux does not occur. Exogenously added LXR ligands, which mimic cholesterol accumulation, cause LXRβ to dissociate from ABCA1, thus freeing ABCA1 for apoA-I binding and subsequent cholesterol efflux. Photoaffinity labeling experiments with 8-azido-[α-(32)P]ATP showed that the interaction of LXRβ with ABCA1 inhibits ATP binding by ABCA1. This is the first study to show that a protein-protein interaction with the endogenous protein suppresses the function of ABC proteins by inhibiting ATP binding. LXRβ can cause a post-translational response by binding directly to ABCA1, as well as a transcriptional response, to maintain cholesterol homeostasis.
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Affiliation(s)
- Masako Hozoji-Inada
- Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto, Japan
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Design principles of nuclear receptor signaling: how complex networking improves signal transduction. Mol Syst Biol 2011; 6:446. [PMID: 21179018 PMCID: PMC3018161 DOI: 10.1038/msb.2010.102] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 10/21/2010] [Indexed: 12/29/2022] Open
Abstract
Nuclear receptors often function in the cytoplasm. A triple conveyor belt pumps ligand (signal) into the nucleus and onto the DNA. The active export of importins enhances signaling to the nucleus. Sharing a single nuclear pore may reduce rather than increase crosstalk.
Nuclear receptors (NRs) derive their family name from the early observation that they are located in the nucleus, despite responding to extracellular signals such as hormones (e.g., cortisol) (Fanestil and Edelman, 1966). According to the ‘classical' paradigm of NR signaling, the NR resides in the nucleus, attached to a DNA response element, waiting for its ligand to bind. The actual systems have multiple additional features (reviewed in Cutress et al, 2008; Cao et al, 2009; Levin, 2009a; Bunce and Campbell, 2010), such as that NRs shuttle between the nucleus and the cytoplasm (Von Knethen et al, 2010) and ligand addition changes receptor location dynamically (Pratt et al, 1989; Liu and DeFranco, 2000; Kumar et al, 2004, 2006; Tanaka et al, 2005; Heitzer et al, 2007; Prüfer and Boudreaux, 2007; Ricketson et al, 2007; Cutress et al, 2008): Figure 1 summarizes the current understanding of the topology of the reaction networks involved in NR signaling, in systems biological graphical notation (SBGN), with NR activation, importin-α and -β binding, nuclear pore complex (NPC)-mediated import, recycling of importins, NR binding to target promoter sequences, exportin-mediated nuclear export of the NR, exportin cycling and free energy-driven Ran recycling. This topology is surprisingly complex when compared with the ‘classical' paradigm. To address to what extent this extra complexity is just detail or contributes essential functionality, we have simulated the dynamics of the NR transcriptional response in maximally realistic mathematical models of increasingly complex designs. The calculations revealed significant disadvantages of the classical and simplest mechanism for endocrine NR-mediated signaling, i.e., the one with localization of the NR exclusively on the DNA (design 1 in Figure 2A): the transcriptional response was very low (Figure 2B). A high concentration of free NR in the nucleus (design 2) improved sensitivity, but made the responsiveness much slower (Figure 2B). If the NR was equally distributed between the nucleus and the cytoplasm without the NR being able to traverse the nucleocytoplasmic membrane (design 3), then, although the NR diffuses more slowly than the much smaller ligand molecule, the higher concentration of the NR increased flux from the plasma membrane to the nuclear membrane; the steady state was reached faster (Figure 2B and C; compare design 3 relative to design 2). Enabling the NR to traverse the nucleocytoplasmic membrane (design 4), further accelerated the response (Figure 2B and C). Designs 1–4 considered the permeation of the NR through the nuclear membrane to be passive, implying an import/export activity ratio of 1. When varying the import to export activity ratio (design 5), a trade-off between the fast responsiveness of design 4 and the high sensitivity of design 2 was calculated (Figure 2B). In order to maximize responsiveness, core-NR should be concentrated in the cytoplasm, whereas to gain sensitivity, liganded NR should be concentrated in the nucleus. This suggested that performance could be improved by making nuclear import and export selective for liganded over unliganded NR (design 6; Figure 2A). Indeed, retention of core-NR in the cytoplasm provided high influx of ligand into the nucleus (Figure 2D), and also the highest concentration of ligand in the nucleus (Figure 2C): Apart from its classical receptor role in transcription regulation, the NR may function as (part of) an active pump for its ligand, resembling a triple conveyor belt: importins and exportins cycle as conveyor belts and drive the cycling of the third conveyor belt consisting of the NR that pumps ligand into the nucleus. Two other striking features of the NR signaling network (Figure 1) are related to the facts that the energy of GTP hydrolysis is coupled to an active export of importins rather than to direct active import of NR and that the same NPC is used for all transport processes. At first sight, the former may waste free energy and the latter might cause fragility due to interferences between different NRs and other signaling pathways. However, our models show that active nuclear export of importins is a design preventing NR sequestration in the nucleus by nuclear importins and, equally paradoxically, the transport of all cargo through the same NPC makes the transport of any particular cargo robust with respect to perturbations in the availability of any other cargo. Our calculations also predict that there is an optimal ratio of nuclear to cytoplasmic fractions of the NR (Figure 2G) that depends on the specific properties of the ligand and on the transcription activation requirements. This may help to explain the observation that different NRs have different predominant intracellular localizations. Our model calculations are thereby in line with many experimental observations, but specific cases of NR signaling may only exhibit a subset of all features. Our models can aid in identifying which subsets are important in any particular case of NR signaling, as we demonstrate for an example. In this study, we have shown that complex networks of biochemical and signaling reactions can harbor subtle design principles that can be understood rationally in terms of simplified but not simple models (which are available to the reader). The topology of nuclear receptor (NR) signaling is captured in a systems biological graphical notation. This enables us to identify a number of ‘design' aspects of the topology of these networks that might appear unnecessarily complex or even functionally paradoxical. In realistic kinetic models of increasing complexity, calculations show how these features correspond to potentially important design principles, e.g.: (i) cytosolic ‘nuclear' receptor may shuttle signal molecules to the nucleus, (ii) the active export of NRs may ensure that there is sufficient receptor protein to capture ligand at the cytoplasmic membrane, (iii) a three conveyor belts design dissipating GTP-free energy, greatly aids response, (iv) the active export of importins may prevent sequestration of NRs by importins in the nucleus and (v) the unspecific nature of the nuclear pore may ensure signal-flux robustness. In addition, the models developed are suitable for implementation in specific cases of NR-mediated signaling, to predict individual receptor functions and differential sensitivity toward physiological and pharmacological ligands.
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35
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Aagaard MM, Siersbæk R, Mandrup S. Molecular basis for gene-specific transactivation by nuclear receptors. Biochim Biophys Acta Mol Basis Dis 2010; 1812:824-35. [PMID: 21193032 DOI: 10.1016/j.bbadis.2010.12.018] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/14/2010] [Accepted: 12/17/2010] [Indexed: 01/31/2023]
Abstract
Nuclear receptors (NRs) are key transcriptional regulators of metazoan physiology and metabolism. Different NRs bind to similar or even identical core response elements; however, they regulate transcription in a highly receptor- and gene-specific manner. These differences in gene activation can most likely be accounted for by mechanisms involving receptor-specific interactions with DNA as well as receptor-specific interactions with protein complexes binding to adjacent and distant DNA sequences. Here, we review key molecular aspects of transactivation by NRs with special emphasis on the recent advances in the molecular mechanisms responsible for receptor- and gene-specific transcriptional activation. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.
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Affiliation(s)
- Mads M Aagaard
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark
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36
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Hu YW, Zheng L, Wang Q. Regulation of cholesterol homeostasis by liver X receptors. Clin Chim Acta 2010; 411:617-25. [PMID: 20060389 DOI: 10.1016/j.cca.2009.12.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 12/21/2009] [Accepted: 12/21/2009] [Indexed: 12/13/2022]
Abstract
Cellular cholesterol levels reflect a balance between uptake, efflux, and endogenous synthesis. The sterol-responsive transcription factors liver X receptors (LXRalpha and LXRbeta) help maintain cholesterol homeostasis, not only through promotion of cholesterol efflux from peripheral tissues but also through suppression of de novo synthesis and exogenous cholesterol uptake. In this review, we summarize the important role of LXRs in regulating expression of key members that keep cholesterol levels in balance.
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Affiliation(s)
- Yan-Wei Hu
- Laboratory Medicine Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China
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37
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Ford CT, Sherratt MJ, Griffiths CEM, Watson REB. Liver X receptor β: maintenance of epidermal expression in intrinsic and extrinsic skin aging. AGE (DORDRECHT, NETHERLANDS) 2009; 31:365-372. [PMID: 19697157 PMCID: PMC2813049 DOI: 10.1007/s11357-009-9111-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Accepted: 07/27/2009] [Indexed: 05/28/2023]
Abstract
Aging in human skin is the composite of time-dependent intrinsic aging plus photoaging induced by chronic exposure to ultraviolet radiation. Nuclear hormone receptors coordinate diverse processes including metabolic homeostasis. Liver X receptor β (LXRβ) is a close human homologue of daf-12, a regulator of nematode longevity. LXRβ is positively regulated by sirtuin-1 and resveratrol, while LXRβ-null mice show transcriptional profiles similar to those seen in aged human skin. In these studies, we examined LXRβ expression in aged and photoaged human skin. Volunteers were recruited to assess intrinsic aging and photoaging. Epidermal LXRβ mRNA was examined by in situ hybridization while protein was identified by immunofluorescence. No significant changes were observed in either LXRβ mRNA or protein expression between young and aged volunteers (mRNA p = 0.90; protein p = 0.26). Similarly, LXRβ protein expression was unaltered in photoaged skin (p = 0.75). Our data therefore suggest that, while not playing a major role in skin aging, robust cutaneous expression implies a fundamental role for LXRβ in epidermal biology.
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Affiliation(s)
- Christopher T. Ford
- Dermatological Sciences, The University of Manchester, 1.443 Stopford Building, Oxford Road, Manchester, M13 9PT UK
| | - Michael J. Sherratt
- Tissue Injury and Repair, The University of Manchester, 1.443 Stopford Building, Oxford Road, Manchester, M13 9PT UK
| | - Christopher E. M. Griffiths
- Dermatological Sciences, The University of Manchester, 1.443 Stopford Building, Oxford Road, Manchester, M13 9PT UK
| | - Rachel E. B. Watson
- Dermatological Sciences, The University of Manchester, 1.443 Stopford Building, Oxford Road, Manchester, M13 9PT UK
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38
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Fiévet C, Staels B. Liver X receptor modulators: Effects on lipid metabolism and potential use in the treatment of atherosclerosis. Biochem Pharmacol 2009; 77:1316-27. [DOI: 10.1016/j.bcp.2008.11.026] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 11/24/2008] [Accepted: 11/25/2008] [Indexed: 10/21/2022]
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Rantham Prabhakara JP, Feist G, Thomasson S, Thompson A, Schommer E, Ghribi O. Differential effects of 24-hydroxycholesterol and 27-hydroxycholesterol on tyrosine hydroxylase and alpha-synuclein in human neuroblastoma SH-SY5Y cells. J Neurochem 2008; 107:1722-9. [PMID: 19014385 PMCID: PMC3205449 DOI: 10.1111/j.1471-4159.2008.05736.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Evidence suggests that environmental and dietary factors may contribute to the pathogenesis of Parkinson's disease (PD). High dietary intake of cholesterol is such a factor that has been shown to increase or decrease the risk of PD. However, because circulating cholesterol does not cross the blood-brain barrier, the mechanisms linking dietary cholesterol to the pathogenesis of PD remain to be understood. In contrast to cholesterol, the oxidized cholesterol metabolites (oxysterols), 24S-hydroxycholesterol (24-OHC) and 27-hydroxycholesterol (27-OHC), can cross the blood-brain barrier and may place the brain at risk of degeneration. In this study, we incubated the human neuroblastoma SH-SY5Y cells for 24 h with 24-OHC, 27-OHC, or a mixture of 24-OHC plus 27-OHC, and have determined effects on tyrosine hydroxylase (the rate-limiting enzyme in dopamine synthesis) levels, alpha-synuclein levels, and apoptosis. We demonstrate that while 24-OHC increases the levels of tyrosine hydroxylase, 27-OHC increases levels of alpha-synuclein, and induces apoptosis. Our findings show for the first time that oxysterols trigger changes in levels of proteins that are associated with the pathogenesis of PD. As steady state levels of 24-OHC and 27-OHC are tightly regulated in the brain, disturbances in these levels may contribute to the pathogenesis of PD.
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Affiliation(s)
- Jaya Prasanthi Rantham Prabhakara
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
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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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Higuchi N, Kato M, Shundo Y, Tajiri H, Tanaka M, Yamashita N, Kohjima M, Kotoh K, Nakamuta M, Takayanagi R, Enjoji M. Liver X receptor in cooperation with SREBP-1c is a major lipid synthesis regulator in nonalcoholic fatty liver disease. Hepatol Res 2008; 38:1122-9. [PMID: 18684130 DOI: 10.1111/j.1872-034x.2008.00382.x] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AIM Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent causes of liver dysfunction and its incidence has increased markedly. However, the mechanisms involved in the pathogenesis of NAFLD in humans have not been thoroughly investigated. Sterol regulatory element binding protein (SREBP)-1c and carbohydrate responsive element binding protein (ChREBP) are transcriptional factors that regulate the expression of lipogenic genes, including acetyl-CoA carboxylases (ACCs) and fatty acid synthase (FAS). SREBP-1c and ChREBP are transactivated by liver X receptor (LXR), a nuclear receptor that regulates the metabolism of cholesterol and fatty acids. To understand the mechanisms involved in the pathogenesis of NAFLD, we investigated the transcriptional factors and lipogenic genes activated in the liver with NAFLD. METHODS Real-time PCR was carried out on liver biopsy samples from 20 NAFLD patients. The target genes studied were: ACC1, FAS, SREBP-1c, ChREBP, AMP-activated protein kinase (AMPK), and LXRalpha. RESULTS LXRalpha, SREBP-1c, ACC1, and FAS were upregulated in NAFLD patients. Expression levels of LXR were four times greater than those of the controls and correlated significantly with SREBP-1c, but not with ChREBP, levels. CONCLUSIONS These findings suggest that LXR acts as one of the main regulators of lipid metabolism by regulating SREBP-1c expression in NAFLD.
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Affiliation(s)
- Nobito Higuchi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Japan
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Prüfer K, Hernandez C, Gilbreath M. Mutations in the AF-2 region abolish ligand-induced intranuclear immobilization of the liver X receptor alpha. Exp Cell Res 2008; 314:2652-60. [PMID: 18599038 DOI: 10.1016/j.yexcr.2008.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 05/14/2008] [Accepted: 05/15/2008] [Indexed: 11/19/2022]
Abstract
The liver X receptors (LXR) alpha and beta are ligand-induced transcription factors that regulate the expression of genes important for cholesterol metabolism, lipogenesis, and other metabolic pathways. Despite their high degree of similarity, LXRs have redundant as well as nonredundant functions. The regulation of LXRs' intranuclear mobility most likely plays a major role in the regulation of their transcriptional activities. In order to elucidate how ligand binding, receptor-protein and receptor-DNA interactions affect intranuclear receptor mobility, we expressed transcriptionally active yellow fluorescent protein (YFP)-LXR alpha and YFP-LXR beta in Cos-7 cells. We used the fluorescence recovery after photobleaching (FRAP) technique and confocal laser scanning microscopy as well as Triton X-100 permeabilization experiments and fluorescence microscopy to measure differences in the intranuclear mobility between LXR alpha and LXR beta. The image analyses revealed that after agonist binding, LXR alpha exhibits slower intranuclear trafficking and greater intranuclear immobilization compared with LXR beta. In addition, mutational analysis showed that the integrity of the Activation Function (AF)-2 region of LXR alpha is essential for its immobilization whereas the integrity of the DNA binding domain is not. These findings imply that specific protein interactions with the AF-2 region of LXR alpha play a role in its intranuclear immobilization.
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Affiliation(s)
- Kirsten Prüfer
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
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Fessler MB. Liver X Receptor: Crosstalk Node for the Signaling of Lipid Metabolism, Carbohydrate Metabolism, and Innate Immunity. ACTA ACUST UNITED AC 2008; 3:75-81. [PMID: 24563635 DOI: 10.2174/157436208784223170] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Liver X Receptor-α (LXRα, also known as NR1H3) and LXRβ (NR1H2) are members of the nuclear receptor superfamily of ligand-activated transcription factors, a superfamily which includes the more widely known glucocorticoid receptor, estrogen receptor, thyroid receptor, and peroxisome proliferator-activated receptors. The LXRs are activated by physiologic sterol ligands (e.g., oxysterols) and by synthetic agonists. In recent years, our understanding of the importance of LXRs has expanded across several fields of (patho-)physiology. Perhaps best known from a sizeable literature as homeostatic 'cholesterol sensors' that drive transcriptional programs promoting cellular cholesterol efflux, 'reverse cholesterol transport,' and bile acid synthesis, more recent roles for LXRs in glucose homeostasis, atherosclerosis, and innate immunity have also been identified. These discoveries complement an emerging literature that continues to draw surprisingly intimate connections between host metabolism and host defense. The present review will discuss the roles of LXR in the signaling of metabolism and innate immunity, and the potential for synthetic LXR agonists as novel therapeutics in dyslipidemia, atherosclerosis, disordered glucose metabolism, and inflammation.
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Affiliation(s)
- Michael B Fessler
- Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709
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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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Jakobsson T, Osman W, Gustafsson JÅ, Zilliacus J, Wärnmark A. Molecular basis for repression of liver X receptor-mediated gene transcription by receptor-interacting protein 140. Biochem J 2007; 405:31-9. [PMID: 17391100 PMCID: PMC1925237 DOI: 10.1042/bj20070004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Similarities in physiological roles of LXR (liver X receptors) and co-repressor RIP140 (receptor-interacting protein 140) in regulating energy homoeostasis and lipid and glucose metabolism suggest that the effects of LXR could at least partly be mediated by recruitment of the co-repressor RIP140. In the present study, we have elucidated the molecular basis for regulation of LXR transcriptional activity by RIP140. LXR is evenly localized in the nucleus and neither the N-terminal domain nor the LBD (ligand-binding domain) is necessary for nuclear localization. Both LXR subtypes, LXRalpha and LXRbeta, interact with RIP140 and co-localize in diffuse large nuclear domains. Interaction and co-localization are dependent on the LBD of the receptor. The C-terminal domain of RIP140 is sufficient for full repressive effect. None of the C-terminal NR (nuclear receptor)-boxes is required for the co-repressor activity, whereas the NR-box-like motif as well as additional elements in the C-terminal region are required for full repressive function. The C-terminal NR-box-like motif is necessary for interaction with LXRbeta, whereas additional elements are needed for strong interaction with LXRalpha. In conclusion, our results suggest that co-repression of LXR activity by RIP140 involves an atypical binding mode of RIP140 and a repression element in the RIP140 C-terminus.
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Affiliation(s)
- Tomas Jakobsson
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 57 Huddinge, Sweden
| | - Waffa Osman
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 57 Huddinge, Sweden
| | - Jan-Åke Gustafsson
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 57 Huddinge, Sweden
| | - Johanna Zilliacus
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 57 Huddinge, Sweden
| | - Anette Wärnmark
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 57 Huddinge, Sweden
- To whom correspondence should be addressed (email )
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