1
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Ting KKY. Revisiting the role of hypoxia-inducible factors and nuclear factor erythroid 2-related factor 2 in regulating macrophage inflammation and metabolism. Front Cell Infect Microbiol 2024; 14:1403915. [PMID: 39119289 PMCID: PMC11306205 DOI: 10.3389/fcimb.2024.1403915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 07/11/2024] [Indexed: 08/10/2024] Open
Abstract
The recent birth of the immunometabolism field has comprehensively demonstrated how the rewiring of intracellular metabolism is critical for supporting the effector functions of many immune cell types, such as myeloid cells. Among all, the transcriptional regulation mediated by Hypoxia-Inducible Factors (HIFs) and Nuclear factor erythroid 2-related factor 2 (NRF2) have been consistently shown to play critical roles in regulating the glycolytic metabolism, redox homeostasis and inflammatory responses of macrophages (Mφs). Although both of these transcription factors were first discovered back in the 1990s, new advances in understanding their function and regulations have been continuously made in the context of immunometabolism. Therefore, this review attempts to summarize the traditionally and newly identified functions of these transcription factors, including their roles in orchestrating the key events that take place during glycolytic reprogramming in activated myeloid cells, as well as their roles in mediating Mφ inflammatory responses in various bacterial infection models.
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Affiliation(s)
- Kenneth K. Y. Ting
- Department of Immunology, University of Toronto, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
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2
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Mendoza SV, Genetos DC, Yellowley CE. Hypoxia-Inducible Factor-2α Signaling in the Skeletal System. JBMR Plus 2023; 7:e10733. [PMID: 37065626 PMCID: PMC10097641 DOI: 10.1002/jbm4.10733] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/23/2023] [Accepted: 01/29/2023] [Indexed: 02/13/2023] Open
Abstract
Hypoxia-inducible factors (HIFs) are oxygen-dependent heterodimeric transcription factors that mediate molecular responses to reductions in cellular oxygen (hypoxia). HIF signaling involves stable HIF-β subunits and labile, oxygen-sensitive HIF-α subunits. Under hypoxic conditions, the HIF-α subunit is stabilized, complexes with nucleus-confined HIF-β subunit, and transcriptionally regulates hypoxia-adaptive genes. Transcriptional responses to hypoxia include altered energy metabolism, angiogenesis, erythropoiesis, and cell fate. Three isoforms of HIF-α-HIF-1α, HIF-2α, and HIF-3α-are found in diverse cell types. HIF-1α and HIF-2α serve as transcriptional activators, whereas HIF-3α restricts HIF-1α and HIF-2α. The structure and isoform-specific functions of HIF-1α in mediating molecular responses to hypoxia are well established across a wide range of cell and tissue types. The contributions of HIF-2α to hypoxic adaptation are often unconsidered if not outrightly attributed to HIF-1α. This review establishes what is currently known about the diverse roles of HIF-2α in mediating the hypoxic response in skeletal tissues, with specific focus on development and maintenance of skeletal fitness. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Sarah V Mendoza
- Department of Anatomy, Physiology, and Cell Biology, School of Veterinary MedicineUniversity of California, DavisDavisCAUSA
| | - Damian C Genetos
- Department of Anatomy, Physiology, and Cell Biology, School of Veterinary MedicineUniversity of California, DavisDavisCAUSA
| | - Clare E Yellowley
- Department of Anatomy, Physiology, and Cell Biology, School of Veterinary MedicineUniversity of California, DavisDavisCAUSA
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3
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Wang J, Lu P, Xie W. Atypical functions of xenobiotic receptors in lipid and glucose metabolism. MEDICAL REVIEW (2021) 2022; 2:611-624. [PMID: 36785576 PMCID: PMC9912049 DOI: 10.1515/mr-2022-0032] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/08/2022] [Indexed: 12/02/2022]
Abstract
Xenobiotic receptors are traditionally defined as xenobiotic chemical-sensing receptors, the activation of which transcriptionally regulates the expression of enzymes and transporters involved in the metabolism and disposition of xenobiotics. Emerging evidence suggests that "xenobiotic receptors" also have diverse endobiotic functions, including their effects on lipid metabolism and energy metabolism. Dyslipidemia is a major risk factor for cardiovascular disease, diabetes, obesity, metabolic syndrome, stroke, nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH). Understanding the molecular mechanism by which transcriptional factors, including the xenobiotic receptors, regulate lipid homeostasis will help to develop preventive and therapeutic approaches. This review describes recent advances in our understanding the atypical roles of three xenobiotic receptors: aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), and constitutive androstane receptor (CAR), in metabolic disorders, with a particular focus on their effects on lipid and glucose metabolism. Collectively, the literatures suggest the potential values of AhR, PXR and CAR as therapeutic targets for the treatment of NAFLD, NASH, obesity and diabetes, and cardiovascular diseases.
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Affiliation(s)
- Jingyuan Wang
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peipei Lu
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Wen Xie
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
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4
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Dai S, Qu L, Li J, Zhang Y, Jiang L, Wei H, Guo M, Chen X, Chen Y. Structural insight into the ligand binding mechanism of aryl hydrocarbon receptor. Nat Commun 2022; 13:6234. [PMID: 36266304 PMCID: PMC9585082 DOI: 10.1038/s41467-022-33858-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 10/04/2022] [Indexed: 12/25/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR), a member of the basic helix-loop-helix (bHLH) Per-Arnt-Sim (PAS) family of transcription factors, plays important roles in regulating xenobiotic metabolism, cellular differentiation, stem cell maintenance, as well as immunity. More recently, AHR has gained significant interest as a drug target for the development of novel cancer immunotherapy drugs. Detailed understanding of AHR-ligand binding has been hampered for decades by the lack of a three-dimensional structure of the AHR PAS-B domain. Here, we present multiple crystal structures of the Drosophila AHR PAS-B domain, including its apo, ligand-bound, and AHR nuclear translocator (ARNT) PAS-B-bound forms. Together with biochemical and cellular assays, our data reveal structural features of the AHR PAS-B domain, provide insights into the mechanism of AHR ligand binding, and provide the structural basis for the future development of AHR-targeted therapeutics.
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Affiliation(s)
- Shuyan Dai
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Lingzhi Qu
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Jun Li
- grid.461579.8Institute of Clinical Medicine, The First Affiliated Hospital of University of South China, Hengyang, Hunan 421001 China
| | - Ye Zhang
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Longying Jiang
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Hudie Wei
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Ming Guo
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Xiaojuan Chen
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
| | - Yongheng Chen
- grid.216417.70000 0001 0379 7164Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008 China
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5
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Hrdina AI, Kohale IN, Kaushal S, Kelly J, Selin NE, Engelward BP, Kroll JH. The Parallel Transformations of Polycyclic Aromatic Hydrocarbons in the Body and in the Atmosphere. ENVIRONMENTAL HEALTH PERSPECTIVES 2022; 130:25004. [PMID: 35225689 PMCID: PMC8884122 DOI: 10.1289/ehp9984] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/29/2021] [Accepted: 01/10/2022] [Indexed: 05/30/2023]
Abstract
BACKGROUND Polycyclic aromatic hydrocarbons (PAHs) emitted from combustion sources are known to be mutagenic, with more potent species also being carcinogenic. Previous studies show that PAHs can undergo complex transformations both in the body and in the atmosphere, yet these transformation processes are generally investigated separately. OBJECTIVES Drawing from the literature in atmospheric chemistry and toxicology, we highlight the parallel transformations of PAHs that occur in the atmosphere and the body and discuss implications for public health. We also examine key uncertainties related to the toxicity of atmospheric oxidation products of PAHs and explore critical areas for future research. DISCUSSION We focus on a key mode of toxicity for PAHs, in which metabolic processes (driven by cytochrome P450 enzymes), leads to the formation of oxidized PAHs that can damage DNA. Such species can also be formed abiotically in the atmosphere from natural oxidation processes, potentially augmenting PAH toxicity by skipping the necessary metabolic steps that activate their mutagenicity. Despite the large body of literature related to these two general pathways, the extent to which atmospheric oxidation affects a PAH's overall toxicity remains highly uncertain. Combining knowledge and promoting collaboration across both fields can help identify key oxidation pathways and the resulting products that impact public health. CONCLUSIONS Cross-disciplinary research, in which toxicology studies evaluate atmospheric oxidation products and their mixtures, and atmospheric measurements examine the formation of compounds that are known to be most toxic. Close collaboration between research communities can help narrow down which PAHs, and which PAH degradation products, should be targeted when assessing public health risks. https://doi.org/10.1289/EHP9984.
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Affiliation(s)
- Amy I.H. Hrdina
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, USA
| | - Ishwar N. Kohale
- Department of Biological Engineering, MIT, Cambridge, Massachusetts, USA
| | - Simran Kaushal
- Department of Biological Engineering, MIT, Cambridge, Massachusetts, USA
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Jamie Kelly
- Department of Geography, University College London, London, UK
| | - Noelle E. Selin
- Institute for Data, Systems, and Society, MIT, Cambridge, Massachusetts, USA
- Department of Earth, Atmospheric, and Planetary Sciences, MIT, Cambridge, Massachusetts, USA
| | - Bevin P. Engelward
- Department of Biological Engineering, MIT, Cambridge, Massachusetts, USA
| | - Jesse H. Kroll
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, USA
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6
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Vazquez-Rivera E, Rojas B, Parrott JC, Shen AL, Xing Y, Carney PR, Bradfield CA. The aryl hydrocarbon receptor as a model PAS sensor. Toxicol Rep 2021; 9:1-11. [PMID: 34950569 PMCID: PMC8671103 DOI: 10.1016/j.toxrep.2021.11.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/19/2021] [Accepted: 11/24/2021] [Indexed: 01/02/2023] Open
Abstract
Proteins containing PER-ARNT-SIM (PAS) domains are commonly associated with environmental adaptation in a variety of organisms. The PAS domain is found in proteins throughout Archaea, Bacteria, and Eukarya and often binds small-molecules, supports protein-protein interactions, and transduces input signals to mediate an adaptive physiological response. Signaling events mediated by PAS sensors can occur through induced phosphorelays or genomic events that are often dependent upon PAS domain interactions. In this perspective, we briefly discuss the diversity of PAS domain containing proteins, with particular emphasis on the prototype member, the aryl hydrocarbon receptor (AHR). This ligand-activated transcription factor acts as a sensor of the chemical environment in humans and many chordates. We conclude with the idea that since mammalian PAS proteins often act through PAS-PAS dimers, undocumented interactions of this type may link biological processes that we currently think of as independent. To support this idea, we present a framework to guide future experiments aimed at fully elucidating the spectrum of PAS-PAS interactions with an eye towards understanding how they might influence environmental sensing in human and wildlife populations.
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Affiliation(s)
- Emmanuel Vazquez-Rivera
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Brenda Rojas
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Jessica C. Parrott
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Anna L. Shen
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Yongna Xing
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Patrick R. Carney
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
| | - Christopher A. Bradfield
- Molecular and Environmental Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, United States
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7
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Zaragoza-Ojeda M, Apatiga-Vega E, Arenas-Huertero F. Role of aryl hydrocarbon receptor in central nervous system tumors: Biological and therapeutic implications. Oncol Lett 2021; 21:460. [PMID: 33907570 PMCID: PMC8063300 DOI: 10.3892/ol.2021.12721] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, whose canonical pathway mainly regulates the genes involved in xenobiotic metabolism. However, it can also regulate several responses in a non-canonical manner, such as proliferation, differentiation, cell death and cell adhesion. AhR plays an important role in central nervous system tumors, as it can regulate several cellular responses via different pathways. The polymorphisms of the AHR gene have been associated with the development of gliomas. In addition, the metabolism of tumor cells promotes tumor growth, particularly in tryptophan synthesis, where some metabolites, such as kynurenine, can activate the AhR pathway, triggering cell proliferation in astrocytomas, medulloblastomas and glioblastomas. Furthermore, as part of the changes in neuroblastomas, AHR is able to downregulate the expression of proto-oncogene c-Myc, induce differentiation in tumor cells, and cause cell cycle arrest and apoptosis. Collectively, these data suggested that the modulation of the AhR pathway may downregulate tumor growth, providing a novel strategy for applications for the treatment of certain tumors through the control of the AhR pathway.
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Affiliation(s)
- Montserrat Zaragoza-Ojeda
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, México.,Posgrado en Ciencias Biológicas, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, México
| | - Elisa Apatiga-Vega
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, México
| | - Francisco Arenas-Huertero
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Mexico City 06720, México
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8
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Wang Z, Snyder M, Kenison JE, Yang K, Lara B, Lydell E, Bennani K, Novikov O, Federico A, Monti S, Sherr DH. How the AHR Became Important in Cancer: The Role of Chronically Active AHR in Cancer Aggression. Int J Mol Sci 2020; 22:ijms22010387. [PMID: 33396563 PMCID: PMC7795223 DOI: 10.3390/ijms22010387] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 12/25/2020] [Accepted: 12/28/2020] [Indexed: 12/13/2022] Open
Abstract
For decades, the aryl hydrocarbon receptor (AHR) was studied for its role in environmental chemical toxicity i.e., as a quirk of nature and a mediator of unintended consequences of human pollution. During that period, it was not certain that the AHR had a “normal” physiological function. However, the ongoing accumulation of data from an ever-expanding variety of studies on cancer, cancer immunity, autoimmunity, organ development, and other areas bears witness to a staggering array of AHR-controlled normal and pathological activities. The objective of this review is to discuss how the AHR has gone from a likely contributor to genotoxic environmental carcinogen-induced cancer to a master regulator of malignant cell progression and cancer aggression. Particular focus is placed on the association between AHR activity and poor cancer outcomes, feedback loops that control chronic AHR activity in cancer, and the role of chronically active AHR in driving cancer cell invasion, migration, cancer stem cell characteristics, and survival.
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Affiliation(s)
- Zhongyan Wang
- Department of Environmental Health, Boston University School of Public Health, Boston, MA 02118, USA; (Z.W.); (K.Y.); (E.L.)
| | - Megan Snyder
- Graduate Program in Genetics and Genomics, Division of Graduate Medical Sciences, Boston University School of Medicine, Boston, MA 02118, USA;
| | - Jessica E. Kenison
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA 02118, USA;
| | - Kangkang Yang
- Department of Environmental Health, Boston University School of Public Health, Boston, MA 02118, USA; (Z.W.); (K.Y.); (E.L.)
| | - Brian Lara
- Department of Environmental Health, Boston University, Boston, MA 02118, USA; (B.L.); (K.B.)
| | - Emily Lydell
- Department of Environmental Health, Boston University School of Public Health, Boston, MA 02118, USA; (Z.W.); (K.Y.); (E.L.)
| | - Kawtar Bennani
- Department of Environmental Health, Boston University, Boston, MA 02118, USA; (B.L.); (K.B.)
| | | | - Anthony Federico
- Division of Computational Biomedicine, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA; (A.F.); (S.M.)
| | - Stefano Monti
- Division of Computational Biomedicine, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA; (A.F.); (S.M.)
| | - David H. Sherr
- Department of Environmental Health, Boston University School of Public Health, Boston, MA 02118, USA; (Z.W.); (K.Y.); (E.L.)
- Correspondence: ; Tel.: +1-617-358-1707
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9
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Kim SA, Jo SH, Cho JH, Yu MY, Shin HC, Kim JA, Park SG, Park BC, Kim S, Kim JH. Aryl Sulfonamides Induce Degradation of Aryl Hydrocarbon Receptor Nuclear Translocator through CRL4 DCAF15 E3 Ligase. Mol Cells 2020; 43:935-944. [PMID: 33168788 PMCID: PMC7700843 DOI: 10.14348/molcells.2020.0122] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 12/24/2022] Open
Abstract
Aryl hydrocarbon receptor nuclear translocator (ARNT) plays an essential role in maintaining cellular homeostasis in response to environmental stress. Under conditions of hypoxia or xenobiotic exposure, ARNT regulates the subset of genes involved in adaptive responses, by forming heterodimers with hypoxia-inducible transcription factors (HIF1α and HIF2α) or aryl hydrocarbon receptor (AhR). Here, we have shown that ARNT interacts with DDB1 and CUL4-associated factor 15 (DCAF15), and the aryl sulfonamides, indisulam and E7820, induce its proteasomal degradation through Cullin-RING finger ligase 4 containing DCAF15 (CRL4DCAF15) E3 ligase. Moreover, the two known neo-substrates of aryl sulfonamide, RNA-binding motif protein 39 (RBM39) and RNA-binding motif protein 23 (RBM23), are not required for ARNT degradation. In line with this finding, aryl sulfonamides inhibited the transcriptional activities of HIFs and AhR associated with ARNT. Our results collectively support novel regulatory roles of aryl sulfonamides in both hypoxic and xenobiotic responses.
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Affiliation(s)
- Sung Ah Kim
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 34113, Korea
| | - Seung-Hyun Jo
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 34113, Korea
| | - Jin Hwa Cho
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
| | - Min Yeong Yu
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 34113, Korea
| | - Ho-Chul Shin
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
| | - Jung-Ae Kim
- Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 34113, Korea
| | - Sung Goo Park
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 34113, Korea
| | - Byoung Chul Park
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Bio-Analytical Science, University of Science and Technology, Daejeon 34113, Korea
| | - Sunhong Kim
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Biomolecular Science, University of Science and Technology, Daejeon 34113, Korea
- Present address: Drug Discovery Center, LG Chem, Ltd., Seoul 07336, Korea
| | - Jeong-Hoon Kim
- Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea
- Department of Functional Genomics, University of Science and Technology, Daejeon 34113, Korea
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10
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Avilla MN, Malecki KMC, Hahn ME, Wilson RH, Bradfield CA. The Ah Receptor: Adaptive Metabolism, Ligand Diversity, and the Xenokine Model. Chem Res Toxicol 2020; 33:860-879. [PMID: 32259433 PMCID: PMC7175458 DOI: 10.1021/acs.chemrestox.9b00476] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Indexed: 12/12/2022]
Abstract
The Ah receptor (AHR) has been studied for almost five decades. Yet, we still have many important questions about its role in normal physiology and development. Moreover, we still do not fully understand how this protein mediates the adverse effects of a variety of environmental pollutants, such as the polycyclic aromatic hydrocarbons (PAHs), the chlorinated dibenzo-p-dioxins ("dioxins"), and many polyhalogenated biphenyls. To provide a platform for future research, we provide the historical underpinnings of our current state of knowledge about AHR signal transduction, identify a few areas of needed research, and then develop concepts such as adaptive metabolism, ligand structural diversity, and the importance of proligands in receptor activation. We finish with a discussion of the cognate physiological role of the AHR, our perspective on why this receptor is so highly conserved, and how we might think about its cognate ligands in the future.
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Affiliation(s)
- Mele N. Avilla
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
| | - Kristen M. C. Malecki
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
| | - Mark E. Hahn
- Biology
Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543-1050, United States
| | - Rachel H. Wilson
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
| | - Christopher A. Bradfield
- Molecular and Environmental Toxicology
Center, Department of Population Health
Sciences, University of Wisconsin School
of Medicine and Public Health, Madison, Wisconsin 53726-2379, United States
- McArdle
Laboratory for Cancer Research, University of Wisconsin School of Medicine
and Public Health, Madison, Wisconsin 53705-227, United States
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11
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Arenas-Huertero F, Zaragoza-Ojeda M, Sánchez-Alarcón J, Milić M, Šegvić Klarić M, Montiel-González JM, Valencia-Quintana R. Involvement of Ahr Pathway in Toxicity of Aflatoxins and Other Mycotoxins. Front Microbiol 2019; 10:2347. [PMID: 31681212 PMCID: PMC6798329 DOI: 10.3389/fmicb.2019.02347] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 09/26/2019] [Indexed: 12/18/2022] Open
Abstract
The purpose of this review is to present information about the role of activation of aflatoxins and other mycotoxins, of the aryl hydrocarbon receptor (AhR) pathway. Aflatoxins and other mycotoxins are a diverse group of secondary metabolites that can be contaminants in a broad range of agricultural products and feeds. Some species of Aspergillus, Alternaria, Penicilium, and Fusarium are major producers of mycotoxins, some of which are toxic and carcinogenic. Several aflatoxins are planar molecules that can activate the AhR. AhR participates in the detoxification of several xenobiotic substances and activates phase I and phase II detoxification pathways. But it is important to recognize that AhR activation also affects differentiation, cell adhesion, proliferation, and immune response among others. Any examination of the effects of aflatoxins and other toxins that act as activators to AhR must consider the potential of the disruption of several cellular functions in order to extend the perception thus far about the toxic and carcinogenic effects of these toxins. There have been no Reviews of existing data between the relation of AhR and aflatoxins and this one attempts to give information precisely about this dichotomy.
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Affiliation(s)
- Francisco Arenas-Huertero
- Experimental Pathology Research Laboratory, Children’s Hospital of Mexico Federico Gómez, Mexico, Mexico
| | - Montserrat Zaragoza-Ojeda
- Experimental Pathology Research Laboratory, Children’s Hospital of Mexico Federico Gómez, Mexico, Mexico
| | - Juana Sánchez-Alarcón
- Rafael Villalobos-Pietrini Laboratory of Genomic Toxicology and Environmental Chemistry, Faculty of Agrobiology, Autonomous University of Tlaxcala, Tlaxcala, Mexico
| | - Mirta Milić
- Mutagenesis Unit, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Maja Šegvić Klarić
- Department of Microbiology, Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia
| | - José M. Montiel-González
- Rafael Villalobos-Pietrini Laboratory of Genomic Toxicology and Environmental Chemistry, Faculty of Agrobiology, Autonomous University of Tlaxcala, Tlaxcala, Mexico
| | - Rafael Valencia-Quintana
- Rafael Villalobos-Pietrini Laboratory of Genomic Toxicology and Environmental Chemistry, Faculty of Agrobiology, Autonomous University of Tlaxcala, Tlaxcala, Mexico
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12
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Zhu R, Gao C, Wang L, Zhang G, Zhang W, Zhang Z, Shen L, Wang S. Involvement of Aryl Hydrocarbon Receptor and Aryl Hydrocarbon Receptor Repressor in Helicobacter Pylori-related Gastric Pathogenesis. J Cancer 2018; 9:2757-2764. [PMID: 30087718 PMCID: PMC6072820 DOI: 10.7150/jca.26083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/09/2018] [Indexed: 01/01/2023] Open
Abstract
Background: Persistent Helicobacter pylori (H. pylori) infection leads to various gastric diseases. Multiple studies have demonstrated that aryl hydrocarbon receptor (AHR) plays roles in the antibacterial response and aryl hydrocarbon receptor repressor (AHRR) is downregulated in stomach cancer. However, the role of AHR or AHRR in H. pylori-related gastric diseases remains unclear. Aims: To investigate whether AHR or AHRR is involved in H. pylori-related gastric diseases. Methods: Patients with gastritis or gastric adenocarcinoma were enrolled randomly, and gastric tissue specimens were diagnosed pathologically. AHR, AHRR, and H. pylori infection status in tissues were detected by immunohistochemistry. Human gastric cells were cocultured with H. pylori. siRNAs were used to silence AHR or AHRR, and a C57bl/6 mouse model colonized by H. pylori was established. Protein expression was determined by western blotting analysis, and TNF, IL-8 and IL-1β in cell supernatants were measured by ELISA. Results: AHR and AHRR were expressed in gastritis tissues and gastric cancer tissues without H. pylori infection, and principally located in the cytoplasm and nucleus. AHR expression was significantly correlated with AHRR expression in gastric tissues without H. pylori infection (P=0.008). However, their expressions were negatively correlated with H. pylori infection status. H. pylori coculture inhibited AHR and AHRR expression in stomach mucosa in vitro and in vivo. Gastric cells produced more TNF, IL-8 and IL-1β when AHR or AHRR was silenced. Conclusions: This preliminary study indicates that AHR and AHRR may be involved in H. pylori-related gastric pathogenesis, and helps toward understanding of inflammation-initiated carcinogenesis of gastric cancer.
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Affiliation(s)
- Renfei Zhu
- Division of Gastrointestinal Surgery, Department of General Surgery, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China.,Department of Hepatobiliary Surgery, Third People's Hospital of Nantong, Nantong 226000, China
| | - Cheng Gao
- Division of Gastrointestinal Surgery, Department of General Surgery, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Liuhua Wang
- Division of Gastrointestinal Surgery, Department of General Surgery, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Guoxin Zhang
- Department of Gastroenterology, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Weiming Zhang
- Department of Pathology, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Zhihong Zhang
- Department of Pathology, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Lizong Shen
- Division of Gastrointestinal Surgery, Department of General Surgery, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
| | - Shoulin Wang
- School of Public Health, Nanjing Medical University, Nanjing 211166, China
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13
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Corrada D, Denison MS, Bonati L. Structural modeling of the AhR:ARNT complex in the bHLH-PASA-PASB region elucidates the key determinants of dimerization. MOLECULAR BIOSYSTEMS 2017; 13:981-990. [PMID: 28393157 PMCID: PMC5576476 DOI: 10.1039/c7mb00005g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Elucidation of the dimerization process of the aryl hydrocarbon receptor (AhR) with the AhR nuclear translocator (ARNT) is crucial for understanding the mechanisms underlying the functional activity of AhR, including mediation of the toxicity of environmental contaminants. In this work, for the first time a structural model of the AhR:ARNT dimer encompassing the entire bHLH-PASA-PASB domain region is proposed. It is developed by using a template-based modeling approach, relying on the recently available crystallographic structures of two dimers of homologous systems in the bHLH-PAS family of proteins: the CLOCK:BMAL1 and the HIF2α:ARNT heterodimers. The structural and energetic characteristics of the modeled AhR:ARNT protein-protein interface are determined by evaluating the variations in solvent accessible surface area, the total binding free energy and the per-residue free energy contributions obtained by the MM-GBSA method and the Energy Decomposition Analysis. The analyses of the intricate network of inter-domain interactions at the dimerization interfaces provide insights into the key determinants of dimerization. These are confirmed by comparison of the computational findings with the available experimental mutagenesis and functional analysis data. The results presented here on the AhR:ARNT dimer structure and interactions provide a framework to start analyzing the mechanism of AhR transformation into its functional DNA binding form.
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Affiliation(s)
- Dario Corrada
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza, 1 - 20126, Milan, Italy.
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14
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Molecular modeling of the AhR structure and interactions can shed light on ligand-dependent activation and transformation mechanisms. CURRENT OPINION IN TOXICOLOGY 2017; 2:42-49. [PMID: 28497129 DOI: 10.1016/j.cotox.2017.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Molecular modeling has given important contributions to elucidation of the main stages in the AhR signal transduction pathway. Despite the lack of experimentally determined structures of the AhR functional domains, information derived from homologous systems has been exploited for modeling their structure and interactions. Homology models of the AhR PASB domain have provided information on the binding cavity and contributed to elucidate species-specific differences in ligand binding. Molecular Docking simulations of the ligand binding process have given insights into differences in binding of diverse agonists, antagonists, and selective AhR modulators, and their application to virtual screening of large databases of compounds have allowed identification of novel AhR ligands. Recently available structural information on protein-protein and protein-DNA complexes of other bHLH-PAS systems has opened the way for modeling the AhR:ARNT dimer structure and investigating the mechanisms of AhR transformation and DNA binding. Future research directions should include simulation of the protein dynamics to obtain a more reliable description of intermolecular interactions involved in signal transmission.
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15
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Immunohistochemical detection of early myocardial infarction: a systematic review. Int J Legal Med 2016; 131:411-421. [PMID: 27885432 DOI: 10.1007/s00414-016-1494-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/08/2016] [Indexed: 12/11/2022]
Abstract
The postmortem diagnosis of early myocardial infarction is a challenge for forensic pathologists because the routine histology is neither specific. Many authors have suggested the use of the immunohistochemistry to fill the gaps in the histological diagnosis of early myocardial infarction. This review aims to analyse advances of immunohistochemical detection of early cardiac damage due to ischaemia. To this purpose, we reviewed experimental studies that investigated immunohistochemical markers and their estimated timing of expression. The review was performed according to specific inclusion and exclusion criteria, and a total of 23 studies assessing the immunohistochemical markers for the diagnosis and timing of early myocardial infarction were identified. The literature review highlights that the analysed markers are complement components, others being inflammatory mediators, cardiac cell proteins, plasma proteins, stress or hypoxia-induced factors and proteins associated with heart failure. All studies demonstrate the effectiveness of the tested markers in the early detection of myocardial infarction in both animal and human samples.
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16
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Corrada D, Soshilov AA, Denison MS, Bonati L. Deciphering Dimerization Modes of PAS Domains: Computational and Experimental Analyses of the AhR:ARNT Complex Reveal New Insights Into the Mechanisms of AhR Transformation. PLoS Comput Biol 2016; 12:e1004981. [PMID: 27295348 PMCID: PMC4905635 DOI: 10.1371/journal.pcbi.1004981] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 05/12/2016] [Indexed: 01/15/2023] Open
Abstract
The Aryl hydrocarbon Receptor (AhR) is a transcription factor that mediates the biochemical response to xenobiotics and the toxic effects of a number of environmental contaminants, including dioxins. Recently, endogenous regulatory roles for the AhR in normal physiology and development have also been reported, thus extending the interest in understanding its molecular mechanisms of activation. Since dimerization with the AhR Nuclear Translocator (ARNT) protein, occurring through the Helix-Loop-Helix (HLH) and PER-ARNT-SIM (PAS) domains, is needed to convert the AhR into its transcriptionally active form, deciphering the AhR:ARNT dimerization mode would provide insights into the mechanisms of AhR transformation. Here we present homology models of the murine AhR:ARNT PAS domain dimer developed using recently available X-ray structures of other bHLH-PAS protein dimers. Due to the different reciprocal orientation and interaction surfaces in the different template dimers, two alternative models were developed for both the PAS-A and PAS-B dimers and they were characterized by combining a number of computational evaluations. Both well-established hot spot prediction methods and new approaches to analyze individual residue and residue-pairwise contributions to the MM-GBSA binding free energies were adopted to predict residues critical for dimer stabilization. On this basis, a mutagenesis strategy for both the murine AhR and ARNT proteins was designed and ligand-dependent DNA binding ability of the AhR:ARNT heterodimer mutants was evaluated. While functional analysis disfavored the HIF2α:ARNT heterodimer-based PAS-B model, most mutants derived from the CLOCK:BMAL1-based AhR:ARNT dimer models of both the PAS-A and the PAS-B dramatically decreased the levels of DNA binding, suggesting this latter model as the most suitable for describing AhR:ARNT dimerization. These novel results open new research directions focused at elucidating basic molecular mechanisms underlying the functional activity of the AhR. Computational modeling combined with experimental validation may give insight into structural and functional properties of protein systems. The basic Helix-Loop-Helix PER-ARNT-SIM (bHLH-PAS) proteins show conserved functional domains despite the broad range of functions exerted by the different systems. Within this protein family, the Aryl hydrocarbon Receptor (AhR) is known to mediate the toxic effects of a number of environmental contaminants, including dioxins and dioxin-like chemicals, and it also exerts other biochemical and physiological effects. Despite the absence of experimentally determined structures, theoretical models of the AhR PAS domains developed on the basis of homologous systems have allowed understanding of some aspects of the molecular mechanisms underlying its function. In this work we present alternative structural models of the transcriptionally active complex of AhR with the AhR Nuclear Translocator (ARNT) protein. Computational characterization of the modeled protein-protein interaction interfaces guided the design of mutagenesis experiments, and evaluation of the DNA binding ability of the resulting AhR:ARNT dimer mutants allowed validation of the models and selection of the most reliable one. These findings open new research directions for understanding the molecular mechanisms underlying the functional activity of the AhR.
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Affiliation(s)
- Dario Corrada
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
| | - Anatoly A. Soshilov
- Department of Environmental Toxicology, University of California, Davis, Davis, California, United States of America
| | - Michael S. Denison
- Department of Environmental Toxicology, University of California, Davis, Davis, California, United States of America
| | - Laura Bonati
- Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
- * E-mail:
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17
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Kimura Y, Kasamatsu A, Nakashima D, Yamatoji M, Minakawa Y, Koike K, Fushimi K, Higo M, Endo-Sakamoto Y, Shiiba M, Tanzawa H, Uzawa K. ARNT2 Regulates Tumoral Growth in Oral Squamous Cell Carcinoma. J Cancer 2016; 7:702-10. [PMID: 27076852 PMCID: PMC4829557 DOI: 10.7150/jca.14208] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/22/2016] [Indexed: 01/22/2023] Open
Abstract
Aryl hydrocarbon receptor nuclear translocator (ARNT) 2 is a transcriptional factor related to adaptive responses against cellular stress from a xenobiotic substance. Recent evidence indicates ARNT is involved in carcinogenesis and cancer progression; however, little is known about the relevance of ARNT2 in the behavior of oral squamous cell carcinoma (OSCC). In the current study, we evaluated the ARNT2 mRNA and protein expression levels in OSCC in vitro and in vivo and the clinical relationship between ARNT2 expression levels in primary OSCCs and their clinicopathologic status by quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and immunohistochemistry. Using ARNT2 overexpression models, we performed functional analyses to investigate the critical roles of ARNT2 in OSCC. ARNT2 mRNA and protein were down-regulated significantly (P < 0.05 for both comparisons) in nine OSCC-derived cells and primary OSCC (n=100 patients) compared with normal counterparts. In addition to the data from exogenous experiments that ARNT2-overexpressed cells showed decreased cellular proliferation, ARNT2-positive OSCC cases were correlated significantly (P < 0.05) with tumoral size. Since von Hippel-Lindau tumor suppressor, E3 ubiquitin protein ligase, a negative regulator of hypoxia-inducible factor (HIF1)-α, is a downstream molecule of ARNT2, we speculated that HIF1-α and its downstream molecules would have key functions in cellular growth. Consistent with our hypothesis, overexpressed ARNT2 cells showed down-regulation of HIF1-α, which causes hypofunctioning of glucose transporter 1, leading to decreased cellular growth. Our results proposed for the first time that the ARNT2 level is an indicator of cellular proliferation in OSCCs. Therefore, ARNT2 may be a potential therapeutic target against progression of OSCCs.
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Affiliation(s)
- Yasushi Kimura
- 1. Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Atsushi Kasamatsu
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Dai Nakashima
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Masanobu Yamatoji
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Yasuyuki Minakawa
- 1. Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Kazuyuki Koike
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Kazuaki Fushimi
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Morihiro Higo
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Yosuke Endo-Sakamoto
- 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Masashi Shiiba
- 3. Department of Medical Oncology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Hideki Tanzawa
- 1. Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan;; 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Katsuhiro Uzawa
- 1. Department of Oral Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan;; 2. Department of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
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18
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Mackowiak B, Wang H. Mechanisms of xenobiotic receptor activation: Direct vs. indirect. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1130-1140. [PMID: 26877237 DOI: 10.1016/j.bbagrm.2016.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/05/2016] [Accepted: 02/06/2016] [Indexed: 12/31/2022]
Abstract
The so-called xenobiotic receptors (XRs) have functionally evolved into cellular sensors for both endogenous and exogenous stimuli by regulating the transcription of genes encoding drug-metabolizing enzymes and transporters, as well as those involving energy homeostasis, cell proliferation, and/or immune responses. Unlike prototypical steroid hormone receptors, XRs are activated through both direct ligand-binding and ligand-independent (indirect) mechanisms by a plethora of structurally unrelated chemicals. This review covers research literature that discusses direct vs. indirect activation of XRs. A particular focus is centered on the signaling control of the constitutive androstane receptor (CAR), the pregnane X receptor (PXR), and the aryl hydrocarbon receptor (AhR). We expect that this review will shed light on both the common and distinct mechanisms associated with activation of these three XRs. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
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Affiliation(s)
- Bryan Mackowiak
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, United States.
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19
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E2A Antagonizes PU.1 Activity through Inhibition of DNA Binding. BIOMED RESEARCH INTERNATIONAL 2016; 2016:3983686. [PMID: 26942192 PMCID: PMC4749766 DOI: 10.1155/2016/3983686] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/06/2016] [Indexed: 11/18/2022]
Abstract
Antagonistic interactions between transcription factors contribute to cell fate decisions made by multipotent hematopoietic progenitor cells. Concentration of the transcription factor PU.1 affects myeloid/lymphoid development with high levels of PU.1 directing myeloid cell fate acquisition at the expense of B cell differentiation. High levels of PU.1 may be required for myelopoiesis in order to overcome inhibition of its activity by transcription factors that promote B cell development. The B cell transcription factors, E2A and EBF, are necessary for commitment of multipotential progenitors and lymphoid primed multipotential progenitors to lymphocytes. In this report we hypothesized that factors required for early B cell commitment would bind to PU.1 and antagonize its ability to induce myeloid differentiation. We investigated whether E2A and/or EBF associate with PU.1. We observed that the E2A component, E47, but not EBF, directly binds to PU.1. Additionally E47 represses PU.1-dependent transactivation of the MCSFR promoter through antagonizing PU.1's ability to bind to DNA. Exogenous E47 expression in hematopoietic cells inhibits myeloid differentiation. Our data suggest that E2A antagonism of PU.1 activity contributes to its ability to commit multipotential hematopoietic progenitors to the lymphoid lineages.
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20
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Szöllősi D, Erdei Á, Gyimesi G, Magyar C, Hegedűs T. Access Path to the Ligand Binding Pocket May Play a Role in Xenobiotics Selection by AhR. PLoS One 2016; 11:e0146066. [PMID: 26727491 PMCID: PMC4699818 DOI: 10.1371/journal.pone.0146066] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/11/2015] [Indexed: 11/23/2022] Open
Abstract
Understanding of multidrug binding at the atomic level would facilitate drug design and strategies to modulate drug metabolism, including drug transport, oxidation, and conjugation. Therefore we explored the mechanism of promiscuous binding of small molecules by studying the ligand binding domain, the PAS-B domain of the aryl hydrocarbon receptor (AhR). Because of the low sequence identities of PAS domains to be used for homology modeling, structural features of the widely employed HIF-2α and a more recent suitable template, CLOCK were compared. These structures were used to build AhR PAS-B homology models. We performed molecular dynamics simulations to characterize dynamic properties of the PAS-B domain and the generated conformational ensembles were employed in in silico docking. In order to understand structural and ligand binding features we compared the stability and dynamics of the promiscuous AhR PAS-B to other PAS domains exhibiting specific interactions or no ligand binding function. Our exhaustive in silico binding studies, in which we dock a wide spectrum of ligand molecules to the conformational ensembles, suggest that ligand specificity and selection may be determined not only by the PAS-B domain itself, but also by other parts of AhR and its protein interacting partners. We propose that ligand binding pocket and access channels leading to the pocket play equally important roles in discrimination of endogenous molecules and xenobiotics.
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Affiliation(s)
- Dániel Szöllősi
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, Budapest, 1094, Hungary
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary
| | - Áron Erdei
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, Budapest, 1094, Hungary
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, 1083, Hungary
| | - Gergely Gyimesi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, 3012, Switzerland
| | - Csaba Magyar
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, 1117, Hungary
| | - Tamás Hegedűs
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, Budapest, 1094, Hungary
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, 1094, Hungary
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21
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The Role of the Neuroprotective Factor Npas4 in Cerebral Ischemia. Int J Mol Sci 2015; 16:29011-28. [PMID: 26690124 PMCID: PMC4691091 DOI: 10.3390/ijms161226144] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/28/2015] [Accepted: 11/16/2015] [Indexed: 01/05/2023] Open
Abstract
Stroke is one of the leading causes of death and adult disability in the world. Although many molecules have been documented to have a neuroprotective effect, the majority of these molecules failed to improve the neurological outcomes for patients with brain ischemia. It has been proposed that neuroprotection alone may, in fact, not be adequate for improving the prognosis of ischemic stroke. Neuroprotectants that can regulate other processes which occur in the brain during ischemia could potentially be targets for the development of effective therapeutic interventions in stroke. Neuronal Per-Arnt-Sim domain protein 4 (Npas4) is an activity-dependent transcription factor whose expression is induced in various brain insults, including cerebral ischemia. It has been shown that Npas4 plays an important role in protecting neurons against many types of neurodegenerative insult. Recently, it was demonstrated that Npas4 indeed has a neuroprotective role in ischemic stroke and that Npas4 might be involved in modulating the cell death pathway and inflammatory response. In this review, we summarize the current knowledge of the roles that Npas4 may play in neuroinflammation and ischemia. Understanding how ischemic lesion size in stroke may be reduced through modulation of Npas4-dependent apoptotic and inflammatory pathways could lead to the development of new stroke therapies.
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22
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Ma T, Schreiber CA, Knutson GJ, Khattouti AE, Sakiyama MJ, Hassan M, Charlesworth MC, Madden BJ, Zhou X, Vuk-Pavlović S, Gomez CR. Effects of oxygen on the antigenic landscape of prostate cancer cells. BMC Res Notes 2015; 8:687. [PMID: 26581192 PMCID: PMC4652345 DOI: 10.1186/s13104-015-1633-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/26/2015] [Indexed: 02/07/2023] Open
Abstract
Background Use of allogeneic cancer cells-based immunotherapy for treatment of established prostate cancer (PCa) has only been marginally effective. One reason for failure could stem from the mismatch of antigenic signatures of vaccine cells and cancer in situ. Hence, it is possible that vaccine cells expressed antigens differently than tumor cells in situ. We hypothesized that cells grown in vitro at low oxygen tension (pO2) provide a better antigen match to tumors in situ and could reveal a more relevant antigenic landscape than cells grown in atmospheric pO2. Methods We tested this hypothesis by comparing PCa cells propagated at pO2 = 2 kPa and 20 kPa. To identify potential tumor-associated antigens (TAAs), we prepared PCa cell lysates, resolved them by two-dimensional electrophoresis and immunoblotting using spontaneous antibodies from plasma derived from PCa patients and control subjects. Antibody-labeled spots were analyzed by MALDI-TOF mass spectrometry and validated by ELISA. We selected hypoxia-regulated HSP70 and hnRNP L and hypoxia-independent HSP60 and determined the frequency of plasma samples reacting with these molecules. Results Frequency of HSP60-reactive plasma was low in healthy controls [1.3 % (1/76)], while it was elevated in PCa patients [13.0 % (7/54); p < 0.05]. These data suggest a humoral immune response to HSP60 in PCa. Levels of autoantibodies to HSP70 did not differ from healthy controls [3.7 % (2/54)] in PCa patients [5.3 % (2/38)]. Similarly, hnRNP L autoantibodies did no differ between healthy controls [6.1 % (3/49)] and PCa patients [5.3 % (2/38)]. Conclusions Overall our results suggest the value of hypoxia as a modifier of the cellular and antigenic landscape of PCa cells. By modifying the immune reactivity of PCa cells in culture, manipulation of pO2 can be proposed as a new avenue for improving diagnosis, prognosis and immunotherapy for PCa.
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Affiliation(s)
- Tangeng Ma
- Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
| | - Claire A Schreiber
- Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA.
| | - Gaylord J Knutson
- Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA.
| | - Abdelouahid El Khattouti
- Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
| | - Marcelo J Sakiyama
- Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. .,Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
| | - Mohamed Hassan
- Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. .,Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
| | | | - Benjamin J Madden
- Proteomics Research Center, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA.
| | - Xinchun Zhou
- Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
| | - Stanimir Vuk-Pavlović
- Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. .,Division of Hematology, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. .,Division of Preventive and Occupational Medicine, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA.
| | - Christian R Gomez
- Cancer Institute, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. .,Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. .,Department of Radiation Oncology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA. .,Stem Cell Laboratory, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. .,Division of Hematology, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA. .,Division of Preventive and Occupational Medicine, Department of Internal Medicine, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA.
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Jackson DP, Joshi AD, Elferink CJ. Ah Receptor Pathway Intricacies; Signaling Through Diverse Protein Partners and DNA-Motifs. Toxicol Res (Camb) 2015; 4:1143-1158. [PMID: 26783425 PMCID: PMC4714567 DOI: 10.1039/c4tx00236a] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Ah receptor is a transcription factor that modulates gene expression via interactions with multiple protein partners; these are reviewed, including the novel NC-XRE pathway involving KLF6.
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Regulation of coronafacoyl phytotoxin production by the PAS-LuxR family regulator CfaR in the common scab pathogen Streptomyces scabies. PLoS One 2015; 10:e0122450. [PMID: 25826255 PMCID: PMC4380410 DOI: 10.1371/journal.pone.0122450] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 02/13/2015] [Indexed: 11/19/2022] Open
Abstract
Potato common scab is an economically important crop disease that is characterized by the formation of superficial, raised or pitted lesions on the potato tuber surface. The most widely distributed causative agent of the disease is Streptomyces scabies, which produces the phytotoxic secondary metabolite thaxtomin A that serves as a key virulence factor for the organism. Recently, it was demonstrated that S. scabies can also produce the phytotoxic secondary metabolite coronafacoyl-L-isoleucine (CFA-L-Ile) as well as other related metabolites in minor amounts. The expression of the biosynthetic genes for CFA-L-Ile production is dependent on a PAS-LuxR family transcriptional regulator, CfaR, which is encoded within the phytotoxin biosynthetic gene cluster in S. scabies. In this study, we show that CfaR activates coronafacoyl phytotoxin production by binding to a single site located immediately upstream of the putative -35 hexanucleotide box within the promoter region for the biosynthetic genes. The binding activity of CfaR was shown to require both the LuxR and PAS domains, the latter of which is involved in protein homodimer formation. We also show that CFA-L-Ile production is greatly enhanced in S. scabies by overexpression of both cfaR and a downstream co-transcribed gene, orf1. Our results provide important insight into the regulation of coronafacoyl phytotoxin production, which is thought to contribute to the virulence phenotype of S. scabies. Furthermore, we provide evidence that CfaR is a novel member of the PAS-LuxR family of regulators, members of which are widely distributed among actinomycete bacteria.
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Choi SH, Chung AR, Kang W, Park JY, Lee MS, Hwang SW, Kim DY, Kim SU, Ahn SH, Kim S, Han KH. Silencing of hypoxia-inducible factor-1β induces anti-tumor effects in hepatoma cell lines under tumor hypoxia. PLoS One 2014; 9:e103304. [PMID: 25068796 PMCID: PMC4113399 DOI: 10.1371/journal.pone.0103304] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/27/2014] [Indexed: 12/18/2022] Open
Abstract
Dimerization of hypoxia-inducible factor-1 beta (HIF-1β) [aryl hydrocarbon receptor nuclear translocator (ARNT)] with HIF-1α is involved in various aspects of cancer biology, including proliferation and survival under hypoxic conditions. We investigated the in vitro mechanism by which silencing of HIF-1β leads to the suppression of tumor cell growth and cellular functions. Various hepatocellular carcinoma (HCC) cell lines (Huh-7, Hep3B, and HepG2) were transfected with small interfering RNA (siRNA) against HIF-1β (siHIF-1β) and cultured under hypoxic conditions (1% O2 for 24 h). The expression levels of HIF-1β, HIF-1α, and growth factors were examined by immunoblotting. Tumor growth was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and tumor activity was measured by terminal deoxynucleotidyl transferase dUTP nick end labeling, tumor cell invasion, and migration assays. Under hypoxic conditions, silencing of HIF-1β expression suppressed tumor cell growth and regulated the expression of tumor growth-related factors, such as vascular endothelial growth factor, epidermal growth factor, and hepatocyte growth factor. Suppression of tumor cell invasion and migration was also demonstrated in HIF-1β-silenced HCC cell lines. Silencing of HIF-1β expression may induce anti-tumor effects under hypoxic conditions in HCC cell lines.
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Affiliation(s)
- Sung Hoon Choi
- Brain Korea 21 plus project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Ae Ri Chung
- Brain Korea 21 plus project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Wonseok Kang
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Yonsei Liver Cancer Special Clinic, Yonsei University Health System, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
| | - Jun Yong Park
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Yonsei Liver Cancer Special Clinic, Yonsei University Health System, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
| | - Mi Sol Lee
- Department of Premed, Yonsei University College of Medicine, Seoul, Korea
| | - Shin Won Hwang
- Department of Premed, Yonsei University College of Medicine, Seoul, Korea
| | - Do Young Kim
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Yonsei Liver Cancer Special Clinic, Yonsei University Health System, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
| | - Seung Up Kim
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Yonsei Liver Cancer Special Clinic, Yonsei University Health System, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
| | - Sang Hoon Ahn
- Brain Korea 21 plus project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Yonsei Liver Cancer Special Clinic, Yonsei University Health System, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
| | - Seungtaek Kim
- Brain Korea 21 plus project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
| | - Kwang-Hyub Han
- Brain Korea 21 plus project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
- Yonsei Liver Cancer Special Clinic, Yonsei University Health System, Seoul, Korea
- Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea
- * E-mail:
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Jackson DP, Li H, Mitchell KA, Joshi AD, Elferink CJ. Ah receptor-mediated suppression of liver regeneration through NC-XRE-driven p21Cip1 expression. Mol Pharmacol 2014; 85:533-41. [PMID: 24431146 DOI: 10.1124/mol.113.089730] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies in hepatocyte-derived cell lines and the whole liver established that the aryl hydrocarbon receptor (AhR) can disrupt G1-phase cell cycle progression following exposure to persistent AhR agonists, such as TCDD (dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin). Growth arrest was attributed to inhibition of G1-phase cyclin-dependent kinase 2 (CDK2) activity. The present study examined the effect of TCDD exposure on liver regeneration following 70% partial hepatectomy in mice lacking the Cip/Kip inhibitors p21(Cip1) or p27(Kip1) responsible for regulating CDK2 activity. Assessment of the regenerative process in wild-type, p21(Cip1) knockout, and p27(Kip1) knockout mice confirmed that TCDD-induced inhibition of liver regeneration is entirely dependent on p21(Cip1) expression. Compared with wild-type mice, the absence of p21(Cip1) expression completely abrogated the TCDD inhibition, and accelerated hepatocyte progression through G1 phase during the regenerative process. Analysis of the transcriptional response determined that increased p21(Cip1) expression during liver regeneration involved an AhR-dependent mechanism. Chromatin immunoprecipitation studies revealed that p21(Cip1) induction required AhR binding to the newly characterized nonconsensus xenobiotic response element, in conjunction with the tumor suppressor protein Kruppel-like factor 6 functioning as an AhR binding partner. The evidence also suggests that AhR functionality following partial hepatectomy is dependent on a p21(Cip1)-regulated signaling process, intimately linking AhR biology to the G1-phase cell cycle program.
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Affiliation(s)
- Daniel P Jackson
- Department of Pharmacology and Toxicology (D.P.J., A.D.J., C.J.E.) and Department of Pediatrics (H.L.), University of Texas Medical Branch, Galveston, Texas; and Department of Biological Sciences, Boise State University, Boise, Idaho (K.A.M.)
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Mezrich JD, Nguyen LP, Kennedy G, Nukaya M, Fechner JH, Zhang X, Xing Y, Bradfield CA. SU5416, a VEGF receptor inhibitor and ligand of the AHR, represents a new alternative for immunomodulation. PLoS One 2012; 7:e44547. [PMID: 22970246 PMCID: PMC3435281 DOI: 10.1371/journal.pone.0044547] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 08/08/2012] [Indexed: 11/19/2022] Open
Abstract
The experimental compound SU5416 went as far as Phase III clinical trials as an anticancer agent, putatively because of its activity as a VEGFR-2 inhibitor, but showed poor results. Here, we show that SU5416 is also an aryl hydrocarbon receptor (AHR) agonist with unique properties. Like TCDD, SU5416 favors induction of indoleamine 2,3 dioxygenase (IDO) in immunologically relevant populations such as dendritic cells in an AHR-dependent manner, leading to generation of regulatory T-cells in vitro. These characteristics lead us to suggest that SU5416 may be an ideal clinical agent for treatment of autoimmune diseases and prevention of transplant rejection, two areas where regulatory ligands of the AHR have shown promise. At the same time, AHR agonism might represent a poor characteristic for an anticancer drug, as regulatory T-cells can inhibit clearance of cancer cells, and activation of the AHR can lead to upregulation of xenobiotic metabolizing enzymes that might influence the half-lives of co-administered chemotherapeutic agents. Not only does SU5416 activate the human AHR with a potency approaching 2,3,7,8-tetrachlorodibenzo-p-dioxin, but it also activates polymorphic murine receptor isoforms (encoded by the Ahr(d) and Ahr(b1) alleles) with similar potency, a finding that has rarely been described and may have implications in identifying true endogenous ligands of this receptor.
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Affiliation(s)
- Joshua D Mezrich
- Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America.
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Wang Y, Li Y, Wang D, Li Y, Chang A, Chan WK. Suppression of the hypoxia inducible factor-1 function by redistributing the aryl hydrocarbon receptor nuclear translocator from nucleus to cytoplasm. Cancer Lett 2012; 320:111-21. [PMID: 22306343 DOI: 10.1016/j.canlet.2012.01.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/12/2012] [Accepted: 01/26/2012] [Indexed: 11/19/2022]
Abstract
The aryl hydrocarbon receptor nuclear translocator (ARNT) heterodimerizes with hypoxia inducible factor-1α (HIF-1α), followed by upregulation of genes that are essential for carcinogenesis. We utilized a novel peptide (Ainp1) to address whether the HIF-1α signaling could be suppressed by an ARNT-mediated mechanism. Ainp1 suppresses the HIF-1α-dependent luciferase expression in Hep3B cells and this suppression can be reversed by ARNT. Ainp1 reduces the interaction between ARNT and HIF-1α, suppresses the formation of the HIF-1 gel shift complex, and suppresses the ARNT recruitment to the vegf promoter. These effects are partly mediated by redistribution of the nuclear ARNT contents to the cytoplasm.
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Affiliation(s)
- Yu Wang
- Department of Pharmaceutics and Medicinal Chemistry, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, CA 95211, USA
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Hypoxia Inducible Factor-1: Its Potential Role In Cerebral Ischemia. Cell Mol Neurobiol 2012; 32:491-507. [DOI: 10.1007/s10571-012-9803-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 01/13/2012] [Indexed: 12/16/2022]
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Khuda-Bukhsh AR, Bhattacharyya SS, Paul S, Dutta S, Boujedaini N, Belon P. Modulation of Signal Proteins: A Plausible Mechanism to Explain How a Potentized Drug Secale Cor 30C Diluted beyond Avogadro's Limit Combats Skin Papilloma in Mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2011; 2011:286320. [PMID: 19617203 PMCID: PMC3136355 DOI: 10.1093/ecam/nep084] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 05/28/2009] [Indexed: 01/03/2023]
Abstract
In homeopathy, ability of ultra-high diluted drugs at or above potency 12C (diluted beyond Avogadro's limit) in ameliorating/curing various diseases is often questioned, particularly because the mechanism of action is not precisely known. We tested the hypothesis if suitable modulations of signal proteins could be one of the possible pathways of action of a highly diluted homeopathic drug, Secale cornutum 30C (diluted 10(60) times; Sec cor 30). It could successfully combat DMBA + croton oil-induced skin papilloma in mice as evidenced by histological, cytogenetical, immunofluorescence, ELISA and immunoblot findings. Critical analysis of several signal proteins like AhR, PCNA, Akt, Bcl-2, Bcl-xL, NF-κB and IL-6 and of pro-apoptotic proteins like cytochrome c, Bax, Bad, Apaf, caspase-3 and -9 revealed that Sec cor 30 suitably modulated their expression levels along with amelioration of skin papilloma. FACS data also suggested an increase of cell population at S and G2 phases and decrease in sub-G1 and G1 phages in carcinogen-treated drug-unfed mice, but these were found to be near normal in the Sec cor 30-fed mice. There was reduction in genotoxic and DNA damages in bone marrow cells of Sec Cor 30-fed mice, as revealed from cytogenetic and Comet assays. Changes in histological features of skin papilloma were noted. Immunofluorescence studies of AhR and PCNA also suggested reduced expression of these proteins in Sec cor 30-fed mice, thereby showing its anti-cancer potentials against skin papilloma. Furthermore, this study also supports the hypothesis that potentized homeopathic drugs act at gene regulatory level.
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Affiliation(s)
- Anisur Rahman Khuda-Bukhsh
- Cytogenetics and Molecular Biology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India
| | - Soumya Sundar Bhattacharyya
- Cytogenetics and Molecular Biology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India
| | - Saili Paul
- Cytogenetics and Molecular Biology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India
| | - Suman Dutta
- Cytogenetics and Molecular Biology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India
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NPAS3 is a trachealess homolog critical for lung development and homeostasis. Proc Natl Acad Sci U S A 2009; 106:11691-6. [PMID: 19581591 PMCID: PMC2710647 DOI: 10.1073/pnas.0902426106] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Trachealess (Trh) is a PAS domain transcription factor regulating Drosophila tracheogenesis. No other Trh homolog has been associated with a respiratory phenotype. Seeking homolog(s) regulating lung development, we screened murine genomic DNA using trh oligonucleotides, identifying only Npas3. Npas3 mRNA peaks in lung from E10.5 to E13.5, verified by sequencing, with immunostaining in airway epithelial cells. Npas3-null mice have reduced lung branching morphogenesis but are viable prenatally. Npas3-null newborns die in respiratory distress, with diminished alveolarization, decreased Shh, Fgf9, Fgf10, and Bmp4 mRNAs, and increased Spry2, consistent with reduced FGF signaling. Exogenous FGF10 rescues branching morphogenesis in Npas3-null lungs. In promoter reporter assays, NPAS3 directly upregulates Shh and represses Spry2. Npas3(+/-) mice have a milder lung phenotype, surviving postnatally, but develop emphysema and airways hyperreactivity. Therefore, absence of a developmentally expressed transcription factor can alter downstream gene expression and multiple signaling pathways in organogenesis. NPAS3 haploinsufficiency may also lead to emphysema and asthma.
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Wang XL, Suzuki R, Lee K, Tran T, Gunton JE, Saha AK, Patti ME, Goldfine A, Ruderman NB, Gonzalez FJ, Kahn CR. Ablation of ARNT/HIF1beta in liver alters gluconeogenesis, lipogenic gene expression, and serum ketones. Cell Metab 2009; 9:428-39. [PMID: 19416713 PMCID: PMC2803070 DOI: 10.1016/j.cmet.2009.04.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2007] [Revised: 02/06/2009] [Accepted: 04/13/2009] [Indexed: 12/13/2022]
Abstract
We have previously shown that expression of the transcription factor ARNT/HIF1beta is reduced in islets of humans with type 2 diabetes. We have now found that ARNT is also reduced in livers of diabetics. To study the functional effect of its reduction, we created mice with liver-specific ablation (L-ARNT KO) using ARNT loxP mice and adenoviral-mediated delivery of Cre. L-ARNT KO mice had normal blood glucose but increased fed insulin levels. These mice also exhibited features of type 2 diabetes with increased hepatic gluconeogenesis, increased lipogenic gene expression, and low serum beta-hydroxybutyrate. These effects appear to be secondary to increased expression of CCAAT/enhancer-binding protein alpha (C/EBPalpha), farnesoid X receptor (FXR), and sterol response element-binding protein 1c (SREBP-1c) and a reduction in phosphorylation of AMPK without changes in the expression of enzymes in ketogenesis, fatty acid oxidation, or FGF21. These results demonstrate that a deficiency of ARNT action in the liver, coupled with that in beta cells, could contribute to the metabolic phenotype of human type 2 diabetes.
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Affiliation(s)
- Xiaohui L Wang
- Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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Fong GH. Regulation of angiogenesis by oxygen sensing mechanisms. J Mol Med (Berl) 2009; 87:549-60. [PMID: 19288062 DOI: 10.1007/s00109-009-0458-z] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 12/26/2022]
Abstract
The choices for blood vessels to undergo angiogenesis or stay quiescent are mostly determined by the status of tissue oxygenation. A major link between tissue hypoxia and active angiogenesis is the accumulation of hypoxia-inducible factor (HIF)-alpha subunits which play a major role in the transcriptional activation of genes encoding angiogenic factors. HIF-alpha abundance is negatively regulated by a subfamily of dioxygenases referred to as prolyl hydroxylase domain-containing proteins (PHDs) which use O(2) as a substrate to hydroxylate HIF-alpha subunits and hence tag them for rapid degradation. Under hypoxic conditions, HIF-alpha subunits accumulate due to reduced hydroxylation efficiency and form transcriptionally active heterodimers with HIF-1ss to activate the expression of angiogenic factors and other proteins important for cellular adaptation to hypoxia. Angiogenesis is regulated by a combination of at least two different mechanisms. The paracrine mechanism is mediated by non-endothelial expression of angiogenic factors such as vascular endothelial growth factor (VEGF)-A, which in turn interact with endothelial cell surface receptors to initiate angiogenic activities. In the autocrine mechanism, endothelial cell themselves are induced to express VEGF-A, which collaborate with the paracrine mechanism to support angiogenesis and protect vascular integrity. Because of critical roles of PHDs and HIFs in regulating angiogenic activities, studies are underway to assess their candidacy as targets for angiogenesis therapies.
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Affiliation(s)
- Guo-Hua Fong
- Center for Vascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, 06030, USA.
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Chow HK, Xu J, Shahravan SH, De Jong AT, Chen G, Shin JA. Hybrids of the bHLH and bZIP protein motifs display different DNA-binding activities in vivo vs. in vitro. PLoS One 2008; 3:e3514. [PMID: 18949049 PMCID: PMC2568859 DOI: 10.1371/journal.pone.0003514] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 10/02/2008] [Indexed: 12/18/2022] Open
Abstract
Minimalist hybrids comprising the DNA-binding domain of bHLH/PAS (basic-helix-loop-helix/Per-Arnt-Sim) protein Arnt fused to the leucine zipper (LZ) dimerization domain from bZIP (basic region-leucine zipper) protein C/EBP were designed to bind the E-box DNA site, CACGTG, targeted by bHLHZ (basic-helix-loop-helix-zipper) proteins Myc and Max, as well as the Arnt homodimer. The bHLHZ-like structure of ArntbHLH-C/EBP comprises the Arnt bHLH domain fused to the C/EBP LZ: i.e. swap of the 330 aa PAS domain for the 29 aa LZ. In the yeast one-hybrid assay (Y1H), transcriptional activation from the E-box was strong by ArntbHLH-C/EBP, and undetectable for the truncated ArntbHLH (PAS removed), as detected via readout from the HIS3 and lacZ reporters. In contrast, fluorescence anisotropy titrations showed affinities for the E-box with ArntbHLH-C/EBP and ArntbHLH comparable to other transcription factors (K(d) 148.9 nM and 40.2 nM, respectively), but only under select conditions that maintained folded protein. Although in vivo yeast results and in vitro spectroscopic studies for ArntbHLH-C/EBP targeting the E-box correlate well, the same does not hold for ArntbHLH. As circular dichroism confirms that ArntbHLH-C/EBP is a much more strongly alpha-helical structure than ArntbHLH, we conclude that the nonfunctional ArntbHLH in the Y1H must be due to misfolding, leading to the false negative that this protein is incapable of targeting the E-box. Many experiments, including protein design and selections from large libraries, depend on protein domains remaining well-behaved in the nonnative experimental environment, especially small motifs like the bHLH (60-70 aa). Interestingly, a short helical LZ can serve as a folding- and/or solubility-enhancing tag, an important device given the focus of current research on exploration of vast networks of biomolecular interactions.
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Affiliation(s)
- Hiu-Kwan Chow
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Jing Xu
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - S. Hesam Shahravan
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Antonia T. De Jong
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Gang Chen
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
| | - Jumi A. Shin
- Department of Chemistry, University of Toronto, Mississauga, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
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Beischlag TV, Luis Morales J, Hollingshead BD, Perdew GH. The aryl hydrocarbon receptor complex and the control of gene expression. Crit Rev Eukaryot Gene Expr 2008; 18:207-50. [PMID: 18540824 DOI: 10.1615/critreveukargeneexpr.v18.i3.20] [Citation(s) in RCA: 543] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that controls the expression of a diverse set of genes. The toxicity of the potent AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin is almost exclusively mediated through this receptor. However, the key alterations in gene expression that mediate toxicity are poorly understood. It has been established through characterization of AhR-null mice that the AhR has a required physiological function, yet how endogenous mediators regulate this orphan receptor remains to be established. A picture as to how the AhR/ARNT heterodimer actually mediates gene transcription is starting to emerge. The AhR/ARNT complex can alter transcription both by binding to its cognate response element and through tethering to other transcription factors. In addition, many of the coregulatory proteins necessary for AhR-mediated transcription have been identified. Cross talk between the estrogen receptor and the AhR at the promoter of target genes appears to be an important mode of regulation. Inflammatory signaling pathways and the AhR also appear to be another important site of cross talk at the level of transcription. A major focus of this review is to highlight experimental efforts to characterize nonclassical mechanisms of AhR-mediated modulation of gene transcription.
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Affiliation(s)
- Timothy V Beischlag
- Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, University Park, PA 16802, USA
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36
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Dougherty EJ, Pollenz RS. Analysis of Ah receptor-ARNT and Ah receptor-ARNT2 complexes in vitro and in cell culture. Toxicol Sci 2007; 103:191-206. [PMID: 18096572 DOI: 10.1093/toxsci/kfm300] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
ARNT and ARNT2 proteins are expressed in mammalian and aquatic species and exhibit a high level of amino acid identity in the basic-helix loop-helix PER/ARNT/SIM domains involved in protein interactions and DNA binding. Since the analysis of ARNT2 function at the protein level has been limited, ARNT2 function in aryl hydrocarbon receptor (AHR)-mediated signaling was evaluated and compared to ARNT. In vitro, ARNT and ARNT2 dimerized equally with the AHR in the presence of 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD) and ARNT2 outcompeted ARNT for binding to the AHR when expressed in excess. In contrast, activation of the AHR with 3-methylcholanthrene or benzo[a]pyrene resulted in predominant formation of AHR*ARNT complexes. ARNT2 expressed in Hepa-1 cell culture lines with reduced ARNT protein resulted in minimal induction of endogenous CYP1A1 protein compared to cells expressing ARNT, and mutation of the putative proline residue at amino acid 352 to histidine failed to produce an ARNT2 that could function in AHR-mediated signaling. However, the expression of ARNT2 in wild-type Hepa-1 cells reduced TCDD-mediated induction of endogenous CYP1A1 protein by 30%, even though AHR*ARNT2 complexes could not be detected in nuclear extracts. Western blot analysis of numerous mouse tissues and various cell culture lines showed that both endogenous ARNT and ARNT2 could be detected in cells derived from kidney, central nervous system, and retinal epithelium. Thus, ARNT2 has the ability to dimerize with the liganded AHR in vitro and is influenced by the activating ligand yet appears to be limited in its ability to influence AHR-mediated signaling in cell culture.
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Affiliation(s)
- Edward J Dougherty
- Division of Cell Biology, Microbiology, and Molecular Biology, Department of Biology, University of South Florida, Tampa, Florida 33620, USA
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Rüegg J, Swedenborg E, Wahlström D, Escande A, Balaguer P, Pettersson K, Pongratz I. The transcription factor aryl hydrocarbon receptor nuclear translocator functions as an estrogen receptor beta-selective coactivator, and its recruitment to alternative pathways mediates antiestrogenic effects of dioxin. Mol Endocrinol 2007; 22:304-16. [PMID: 17991765 DOI: 10.1210/me.2007-0128] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The biological effects of dioxins are mediated by the aryl hydrocarbon receptor (AhR) and its dimerization partner, the AhR nuclear translocator (ARNT), and include interference with hormonal signaling pathways like the response to estrogens. The effects of estrogens are mediated by two estrogen receptor (ER) isoforms, ERalpha and ERbeta, which belong to the family of nuclear receptors. We have previously shown that ARNT can act as coactivator of the ERs. In this study, we show that recruitment of ARNT to AhR or hypoxia-inducible factor-1alpha signaling pathways as well as small interfering RNA-mediated down-regulation of ARNT levels lead to a reduction in ER transcriptional activity. Using chromatin immunoprecipitation assays, we demonstrate that this decrease coincides with reduced recruitment of ARNT to estradiol-regulated promoters. We show further that coactivation by ARNT as well as inhibition by dioxin acts stronger on ERbeta than on ERalpha activity. Additionally, we demonstrate that the effects of ARNT are dependent on the A/B domain of the ERs with the A/B domain of ERbeta being considerably stronger in mediating the coactivating effects of ARNT. Taken together, our studies show that recruitment of ARNT to the AhR after dioxin treatment can account for the antiestrogenic effect of dioxins. Moreover, we show for the first time that the inhibitory effects of dioxin are more pronounced on ERbeta than on ERalpha.
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Affiliation(s)
- Joëlle Rüegg
- Department of Biosciences and Nutrition, Karolinska Institute, Huddinge, Sweden
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38
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Lee KH, Park JW, Chun YS. Non-hypoxic transcriptional activation of the aryl hydrocarbon receptor nuclear translocator in concert with a novel hypoxia-inducible factor-1alpha isoform. Nucleic Acids Res 2004; 32:5499-511. [PMID: 15479785 PMCID: PMC524291 DOI: 10.1093/nar/gkh880] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Aryl hydrocarbon receptor nuclear translocator (ARNT) belongs to the basic helix-loop-helix Per-Arnt-Sim (bHLH PAS) protein which dimerizes with other PAS proteins. Although it has a transactivation domain (TAD), ARNT functions as an assistant partner of main factors, such as aryl hydrocarbon receptor and hypoxia-inducible factors, rather than acting as a straightforward transcription factor. However, ARNT may function as an active transcription factor using its TAD either in association with itself, single-minded protein 1, or trachealess protein. In the present study, we identified a novel ARNT partner, a HIF-1alpha variant, which is ubiquitously expressed in human tissues and cancer cell lines. The HIF-1alpha variant, designated HIF-1alpha417, bound to ARNT and, moreover, stimulated the transcription of the erythropoietin enhancer reporter gene. This stimulation was markedly augmented by ARNT but not by the ARNT603 mutant lacking the TAD. Thus, augmentation by ARNT suggests that ARNT determined the transcriptional activity. HIF-1alpha417 was found to be associated with ARNT and to bind to the hypoxia response element containing the E-box core. Moreover, HIF-1alpha417 promoted the nuclear translocation of ARNT, and conversely ARNT stabilized HIF-1alpha417. Taken together, our results suggest that HIF-1alpha417 is a novel partner that is required for transcription activity of ARNT.
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Affiliation(s)
- Kyoung-Hwa Lee
- Department of Pharmacology, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-799, Korea
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39
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Brunnberg S, Pettersson K, Rydin E, Matthews J, Hanberg A, Pongratz I. The basic helix-loop-helix-PAS protein ARNT functions as a potent coactivator of estrogen receptor-dependent transcription. Proc Natl Acad Sci U S A 2003; 100:6517-22. [PMID: 12754377 PMCID: PMC164478 DOI: 10.1073/pnas.1136688100] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The biological effects of estrogens are mediated by the estrogen receptors ERalpha and ERbeta. These receptors regulate gene expression through binding to DNA enhancer elements and subsequently recruiting factors such as coactivators that modulate their transcriptional activity. Here we show that ARNT (aryl hydrocarbon receptor nuclear translocator), the obligatory heterodimerization partner for the aryl hydrocarbon receptor and hypoxia inducible factor 1alpha, functions as a potent coactivator of ERalpha- and ERbeta- dependent transcription. The coactivating effect of ARNT depends on physical interaction with the ERs and involves the C-terminal domain of ARNT and not the structurally conserved basic helix-loop-helix and PAS (Per-ARNT-Sim) motifs. Moreover, we show that ARNT/ER interaction requires the E2-activated ligand binding domain of ERalpha or ERbeta. These observations, together with the previous role of ARNT as an obligatory partner protein for conditionally regulated basic helix-loop-helix-PAS proteins like the aryl hydrocarbon receptor or hypoxia inducible factor 1alpha, expand the cellular functions of ARNT to include regulation of ERalpha and ERbeta transcriptional activity. ARNT was furthermore recruited to a natural ER target gene promoter in a estrogen-dependent manner, supporting a physiological role for ARNT as an ER coactivator.
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Affiliation(s)
- Sara Brunnberg
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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40
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Beischlag TV, Wang S, Rose DW, Torchia J, Reisz-Porszasz S, Muhammad K, Nelson WE, Probst MR, Rosenfeld MG, Hankinson O. Recruitment of the NCoA/SRC-1/p160 family of transcriptional coactivators by the aryl hydrocarbon receptor/aryl hydrocarbon receptor nuclear translocator complex. Mol Cell Biol 2002; 22:4319-33. [PMID: 12024042 PMCID: PMC133867 DOI: 10.1128/mcb.22.12.4319-4333.2002] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2001] [Revised: 12/12/2001] [Accepted: 03/11/2002] [Indexed: 11/20/2022] Open
Abstract
The aryl hydrocarbon receptor complex heterodimeric transcription factor, comprising the basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) domain aryl hydrocarbon receptor (AHR) and aryl hydrocarbon receptor nuclear translocator (ARNT) proteins, mediates the toxic effects of TCDD (2,3,7,8 tetrachlorodibenzo-p-dioxin). The molecular events underlying TCDD-inducible gene activation, beyond the activation of the AHRC, are poorly understood. The SRC-1/NCoA-1, NCoA-2/GRIP-1/TIF-2, and p/CIP/AIB/ACTR proteins have been shown to act as mediators of transcriptional activation. In this report, we demonstrate that SRC-1, NCoA-2, and p/CIP are capable of independently enhancing TCDD-dependent induction of a luciferase reporter gene by the AHR/ARNT dimer. Furthermore, injection of anti-SRC-1 or anti-p/CIP immunoglobulin G into mammalian cells abolishes the transcriptional activity of a TCDD-dependent reporter gene. We demonstrate by coimmunoprecipitation and by a reporter gene assay that SRC-1 and NCoA-2 but not p/CIP are capable of interacting with ARNT in vivo after transient transfection into mammalian cells, while AHR is capable of interacting with all three coactivators. We confirm the interactions of ARNT and AHR with SRC-1 with immunocytochemical techniques. Furthermore, SRC-1, NCoA-2, and p/CIP all associate with the CYP1A1 enhancer region in a TCDD-dependent fashion, as demonstrated by chromatin immunoprecipitation assays. We demonstrate by yeast two-hybrid, glutathione S-transferase pulldown, and mammalian reporter gene assays that ARNT requires its helix 2 domain but not its transactivation domain to interact with SRC-1. This indicates a novel mechanism of action for SRC-1. SRC-1 does not require its bHLH-PAS domain to interact with ARNT or AHR, but utilizes distinct domains proximal to its p300/CBP interaction domain. Taken together, these data support a role for the SRC family of transcriptional coactivators in TCDD-dependent gene regulation.
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Affiliation(s)
- Timothy V Beischlag
- Department of Pathology and Laboratory Medicine, Molecular Biology Institute, and Jonsson Comprehensive Cancer Center, School of Medicine, University of California-Los Angeles, Los Angeles, California 90095, USA
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41
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Abstract
The aryl hydrocarbon receptor (AhR or dioxin receptor) is a ligand-activated transcription factor that heterodimerizes with the AhR nuclear translocator (ARNT/HIF-1beta) to form an AhR/ARNT transcription factor complex. This complex binds to specific DNA sites in the regulatory domains of numerous target genes and mediates the biological effects of exogenous ligands. Herein, we have investigated the subcellular distribution of the AhR/ARNT complex in response to ligand stimulation, by using live-cell confocal and high-resolution deconvolution microscopy. We found that unliganded AhR shows a predominantly cytoplasmic diffuse distribution in mouse hepatoma cells. On addition of ligand, AhR rapidly translocates to the nucleus and accumulates in multiple bright foci. Inhibition of transcription prevented the formation of AhR foci. Dual- and triple-immunolabeling experiments, combined with labeling of nascent RNA, showed that the foci are transcription sites, indicating that upon ligand stimulation, AhR is recruited to active transcription sites. The interaction of AhR with ARNT was both necessary and sufficient for the recruitment of AhR to transcription sites. These results indicate that AhR/ARNT complexes are recruited to specific subnuclear compartments in a ligand-dependent manner and that these foci represent the sites of AhR target genes.
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Affiliation(s)
- Cem Elbi
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5055, USA
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Cheng P, Yang Y, Gardner KH, Liu Y. PAS domain-mediated WC-1/WC-2 interaction is essential for maintaining the steady-state level of WC-1 and the function of both proteins in circadian clock and light responses of Neurospora. Mol Cell Biol 2002; 22:517-24. [PMID: 11756547 PMCID: PMC139750 DOI: 10.1128/mcb.22.2.517-524.2002] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the frq-wc-based circadian feedback loops of Neurospora, two PAS domain-containing transcription factors, WHITE COLLAR-1 (WC-1) and WC-2, form heterodimeric complexes that activate the transcription of frequency (frq). FRQ serves two roles in these feedback loops: repressing its own transcription by interacting with the WC complex and positively upregulating the levels of WC-1 and WC-2 proteins. We report here that the steady-state level of WC-1 protein is independently regulated by both FRQ and WC-2 through different posttranscriptional mechanisms. The WC-1 level is extremely low in wc-2 knockout strains, and this low level of expression is independent of wc-1 transcription and FRQ protein expression. In addition, our data show that the PAS domain of WC-2 mediates the interactions of this protein with both WC-1 and FRQ in vivo. Such interactions are essential for maintaining the steady-state level of WC-1 and the proper function of WC-1 and WC-2 in circadian clock and light responses.
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Affiliation(s)
- Ping Cheng
- Department of Physiology. Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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43
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Mhaskar Y, Armour G, Dunaway G. Alteration of the levels of the M-type 6-phosphofructo-1-kinase mRNA isoforms during neonatal maturation of heart, brain and muscle. Mol Cell Biochem 2000; 214:81-7. [PMID: 11195794 DOI: 10.1023/a:1007195017569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
During muscle, heart, and brain neonatal maturation, the capacity to utilize glucose in energy metabolism is directly related to the extent of accumulation of the 6-phosphofructo-1-kinase (PFK) M-type subunit. Neonatal development of other organs, such as liver and kidney, which are not characterized by large increases in the capacity to use glucose do not exhibit large increases in the M-type subunit protein. The presence of the M-type subunit in a PFK isozyme pool fosters a higher affinity utilization of carbohydrate and increased responsiveness to the levels of regulatory metabolites. To better appreciate this phenomenon, which is vital for normal development, the different isoforms of the M-type subunit mRNA's and alteration of their levels during maturation have been examined. Further, the potential promoter regions, i.e., the regions upstream from the sites of initiation of transcription, which are involved in expression of the different M-type subunit mRNA isoforms have been isolated, sequenced, and examined for possible transcription factor interaction sites. Using cDNA libraries produced from adult rat brain or skeletal muscle RNA, two primary forms of rat M-type subunit cDNA's were detected. Although the translated regions of these mRNA's were essentially identical, the 5'-untranslated region (5'-UTR) exhibited different lengths (90 or 59 bp) and sequences. Each M-type subunit cDNA had 10 common nucleotides immediately upstream from the initiator ATG, and the remaining 5'-UTR's had insignificant identity. A genomic fragment which interacted with probes complimentary to the sequences of the 5'-UTR of each M-type subunit mRNA isoform was isolated and sequenced by primer walking. It was discovered that the 5'-UTR of one of the mRNA's (proximal mRNA) was located immediately upstream from exon I and was apparently transcribed without splicing. Subsequently, the initial bp in the sequence of the other mRNA isoform (distal mRNA) was located 4010 bp upstream from the ATG in exon 1. Employing Reverse Transcription-Polymerase Chain Reaction using total RNA and scanning densitometry, the relative levels of the proximal and distal mRNA's during neonatal maturation of brain, heart, and muscle were measured. In these tissues, both forms of M-type subunit mRNA's were present, and during maturation tissue-specific differences were noted.
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Affiliation(s)
- Y Mhaskar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield 62794-9629, USA
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44
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Pollenz RS, Barbour ER. Analysis of the complex relationship between nuclear export and aryl hydrocarbon receptor-mediated gene regulation. Mol Cell Biol 2000; 20:6095-104. [PMID: 10913191 PMCID: PMC86085 DOI: 10.1128/mcb.20.16.6095-6104.2000] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) contains signals for both nuclear import and nuclear export (NES). The purpose of the studies in this report was to determine the relationship between the nuclear export of the AHR and AHR-mediated gene regulation. Blockage of nuclear export in HepG2 cells with leptomycin B (LMB) resulted in increased levels of AHR-AHR nuclear translocator (ARNT) complex in the nucleus and correlative reductions in agonist-stimulated AHR degradation. However, LMB exposure inhibited agonist-mediated induction of numerous AHR-responsive reporter genes by 75 to 89% and also inhibited induction of endogenous CYP1A1. LMB did not transform the AHR to a ligand binding species or affect activation by TCDD (2, 3,7,8-tetrachlorodibenzo-p-dioxin). Mutagenesis of leucines 66 and 71 of the putative AHR NES resulted in a protein with reduced function in dimerization to ARNT and binding to DNA, while alanine substitution at leucine 69 (AHR(A69)) resulted in an AHR that bound with ARNT and associated with DNA. AHR(A69) protein injected directly into the nuclei of E36 cells remained nuclear following 6 h of agonist stimulation. In transient-transfection assays, AHR(A69) accumulated within the nucleus was not degraded efficiently following agonist exposure. Finally, AHR(A69) supported induction of AHR-responsive reporter genes in an agonist-dependent manner. These findings show that it is possible to generate an AHR protein defective in nuclear export that is functional in agonist-mediated gene induction. This implies that the negative effect of LMB on agonist-mediated gene induction is independent of the nuclear export of the AHR.
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Affiliation(s)
- R S Pollenz
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA.
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45
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Hulkko SM, Wakui H, Zilliacus J. The pro-apoptotic protein death-associated protein 3 (DAP3) interacts with the glucocorticoid receptor and affects the receptor function. Biochem J 2000; 349 Pt 3:885-93. [PMID: 10903152 PMCID: PMC1221218 DOI: 10.1042/bj3490885] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The yeast two-hybrid system was used to isolate cDNAs encoding proteins that interact with the glucocorticoid receptor (GR) ligand-binding domain in a ligand-dependent manner. One isolated cDNA encoded a fragment of death-associated protein 3 (DAP3), which has been implicated as a positive mediator of apoptosis. In vitro experiments showed that the full-length DAP3 also interacted with GR. The main interaction domain was mapped to the N-terminal region of DAP3 that had previously been shown to function in a dominant-negative fashion, protecting cells from apoptosis. Co-transfection experiments in COS-7 cells showed that DAP3 had a stimulatory effect on the ligand-induced transcriptional activation by GR and also increased the steroid-sensitivity. Furthermore, DAP3 formed a complex with several other nuclear receptors and some basic helix-loop-helix/Per-Arnt-Sim proteins, as well as with heat-shock protein 90 (hsp90) (Arnt is the aryl-hydrocarbon-receptor nuclear translocator, and Per and Sim are the Drosophila proteins Period and Single-minded). The results suggest that DAP3 could have an important role in GR action, possibly by modulating the cytoplasmic GR-hsp90 complex. Since glucocorticoids can induce apoptosis, the pro-apoptotic DAP3 protein may be involved in this function of GR.
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Affiliation(s)
- S M Hulkko
- Department of Medical Nutrition, Karolinska Institutet, Novum, S-141 86 Huddinge, Sweden.
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46
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Lee C, Bae K, Edery I. PER and TIM inhibit the DNA binding activity of a Drosophila CLOCK-CYC/dBMAL1 heterodimer without disrupting formation of the heterodimer: a basis for circadian transcription. Mol Cell Biol 1999; 19:5316-25. [PMID: 10409723 PMCID: PMC84375 DOI: 10.1128/mcb.19.8.5316] [Citation(s) in RCA: 201] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Drosophila CLOCK (dCLOCK) and CYCLE (CYC) (also referred to as dBMAL1) proteins are members of the basic helix-loop-helix PAS (PER-ARNT-SIM) superfamily of transcription factors and are required for high-level expression of the circadian clock genes period (per) and timeless (tim). Several lines of evidence indicate that PER, TIM, or a PER-TIM heterodimer somehow inhibit the transcriptional activity of a putative dCLOCK-CYC complex, generating a negative-feedback loop that is a core element of the Drosophila circadian oscillator. In this report we show that PER and/or TIM inhibits the binding of a dCLOCK-CYC heterodimer to an E-box-containing DNA fragment that is present in the 5' nontranscribed region of per and acts as a circadian enhancer element. Surprisingly, inhibition of this DNA binding activity by PER, TIM, or both is not accompanied by disruption of the association between dCLOCK and CYC. The results suggest that the interaction of PER, TIM, or both with the dCLOCK-CYC heterodimer induces a conformational change or masks protein regions in the heterodimer, leading to a reduction in DNA binding activity. Together with other findings, our results strongly suggest that daily cycles in the association of PER and TIM with the dCLOCK-CYC complex probably contribute to rhythmic expression of per and tim.
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Affiliation(s)
- C Lee
- Graduate Program in Microbiology and Molecular Genetics, Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, New Jersey 08854, USA
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47
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Huang LE, Gu J, Schau M, Bunn HF. Regulation of hypoxia-inducible factor 1alpha is mediated by an O2-dependent degradation domain via the ubiquitin-proteasome pathway. Proc Natl Acad Sci U S A 1998; 95:7987-92. [PMID: 9653127 PMCID: PMC20916 DOI: 10.1073/pnas.95.14.7987] [Citation(s) in RCA: 1617] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Hypoxia induces a group of physiologically important genes such as erythropoietin and vascular endothelial growth factor. These genes are transcriptionally up-regulated by hypoxia-inducible factor 1 (HIF-1), a global regulator that belongs to the basic helix-loop-helix PAS family. Although HIF-1 is a heterodimer composed of alpha and beta subunits, its activity is primarily determined by hypoxia-induced stabilization of HIF-1alpha, which is otherwise rapidly degraded in oxygenated cells. We report the identification of an oxygen-dependent degradation (ODD) domain within HIF-1alpha that controls its degradation by the ubiquitin-proteasome pathway. The ODD domain consists of approximately 200 amino acid residues, located in the central region of HIF-1alpha. Because portions of the domain independently confer degradation of HIF-1alpha, deletion of this entire region is required to give rise to a stable HIF-1alpha, capable of heterodimerization, DNA-binding, and transactivation in the absence of hypoxic signaling. Conversely, the ODD domain alone confers oxygen-dependent instability when fused to a stable protein, Gal4. Hence, the ODD domain plays a pivotal role for regulating HIF-1 activity and thereby may provide a means of controlling gene expression by changes in oxygen tension.
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Affiliation(s)
- L E Huang
- Division of Hematology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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48
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Pongratz I, Antonsson C, Whitelaw ML, Poellinger L. Role of the PAS domain in regulation of dimerization and DNA binding specificity of the dioxin receptor. Mol Cell Biol 1998; 18:4079-88. [PMID: 9632792 PMCID: PMC108992 DOI: 10.1128/mcb.18.7.4079] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The dioxin receptor is a ligand-regulated transcription factor that mediates signal transduction by dioxin and related environmental pollutants. The receptor belongs to the basic helix-loop-helix (bHLH)-Per-Arnt-Sim (PAS) family of factors, which, in addition to the bHLH motif, contain a PAS region of homology. Upon activation, the dioxin receptor dimerizes with the bHLH-PAS factor Arnt, enabling the receptor to recognize xenobiotic response elements in the vicinity of target genes. We have studied the role of the PAS domain in dimerization and DNA binding specificity of the dioxin receptor and Arnt by monitoring the abilities of the individual bHLH domains and different bHLH-PAS fragments to dimerize and bind DNA in vitro and recognize target genes in vivo. The minimal bHLH domain of the dioxin receptor formed homodimeric complexes, heterodimerized with full-length Arnt, and together with Arnt was sufficient for recognition of target DNA in vitro and in vivo. In a similar fashion, only the bHLH domain of Arnt was necessary for DNA binding specificity in the presence of the dioxin receptor bHLH domain. Moreover, the bHLH domain of the dioxin receptor displayed a broad dimerization potential, as manifested by complex formation with, e.g. , the unrelated bHLH-Zip transcription factor USF. In contrast, a construct spanning the dioxin receptor bHLH domain and an N-terminal portion of the PAS domain failed to form homodimers and was capable of dimerizing only with Arnt. Thus, the PAS domain is essential to confer dimerization specificity of the dioxin receptor.
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Affiliation(s)
- I Pongratz
- Department of Cell and Molecular Biology, Karolinska Institutet, S-171-77 Stockholm, Sweden
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49
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Moffett P, Reece M, Pelletier J. The murine Sim-2 gene product inhibits transcription by active repression and functional interference. Mol Cell Biol 1997; 17:4933-47. [PMID: 9271372 PMCID: PMC232345 DOI: 10.1128/mcb.17.9.4933] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The Drosophila single-minded (Dsim) gene encodes a master regulatory protein involved in cell fate determination during midline development. This protein is a member of a rapidly expanding family of gene products possessing basic helix-loop-helix (bHLH) and hydrophobic PAS (designated a conserved region among PER, ARNT [aryl hydrocarbon receptor nuclear translocator] and SIM) protein association domains. Members of this family function as central transcriptional regulators in cellular differentiation and in the response to environmental stimuli such as xenobiotics and hypoxia. We have previously identified a murine member of this family, called mSim-2, showing sequence homology to the bHLH and PAS domains of Dsim. Immunoprecipitation experiments with recombinant proteins indicate that mSIM-2 associates with the arnt gene product. In the present work, by using fine-structure mapping we found that the HLH and PAS motifs of both proteins are required for optimal association. Forced expression of GAL4/mSIM-2 fusion constructs in mammalian cells demonstrated the presence of two separable repression domains within the carboxy terminus of mSIM-2. We found that mSIM-2 is capable of repressing ARNT-mediated transcriptional activation in a mammalian two-hybrid system. This effect (i) is dependent on the ability of mSIM-2 and ARNT to heterodimerize, (ii) is dependent on the presence of the mSIM-2 carboxy-terminal repression domain, and (iii) is not specific to the ARNT activation domain. These results suggest that mSIM-2 repression activity can dominantly override the activation potential of adjacent transcription factors. We also demonstrated that mSIM-2 can functionally interfere with hypoxia-inducible factor 1alpha (HIF-1alpha)/ARNT transcription complexes, providing a second mechanism by which mSIM-2 may inhibit transcription.
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Affiliation(s)
- P Moffett
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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50
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Ko HP, Okino ST, Ma Q, Whitlock JP. Transactivation domains facilitate promoter occupancy for the dioxin-inducible CYP1A1 gene in vivo. Mol Cell Biol 1997; 17:3497-507. [PMID: 9199285 PMCID: PMC232203 DOI: 10.1128/mcb.17.7.3497] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have studied the transcriptional regulation of the dioxin-inducible mouse CYP1A1 gene in its native chromosomal setting. We analyzed the ability of aromatic hydrocarbon receptor (AhR) mutants and AhR chimeras to restore dioxin responsiveness to the CYP1A1 gene in AhR-defective mouse hepatoma cells. Our data reveal that transactivation domains in AhR's C-terminal half mediate occupancy of the nuclear factor 1 site and TATA box for the CYP1A1 promoter in vivo. Transactivation domains of VP16 and AhR nuclear translocator, but not Sp1, can substitute for AhR's C-terminal half in facilitating protein binding at the promoter. Our data also reveal an apparent linear relationship between promoter occupancy and CYP1A1 gene expression in chromatin. These findings provide new insights into the in vivo mechanism of transcriptional activation for an interesting mammalian gene.
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Affiliation(s)
- H P Ko
- Department of Molecular Pharmacology, Stanford University School of Medicine, California 94306-5332, USA
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