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Chen T. Unveiling the significance of inducible nitric oxide synthase: Its impact on cancer progression and clinical implications. Cancer Lett 2024; 592:216931. [PMID: 38701892 DOI: 10.1016/j.canlet.2024.216931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 04/14/2024] [Accepted: 04/29/2024] [Indexed: 05/05/2024]
Abstract
The intricate role of inducible nitric oxide synthase (iNOS) in cancer pathophysiology has garnered significant attention, highlighting the complex interplay between tumorigenesis, immune response, and cellular metabolism. As an enzyme responsible for producing nitric oxide (NO) in response to inflammatory stimuli. iNOS is implicated in various aspects of cancer development, including DNA damage, angiogenesis, and evasion of apoptosis. This review synthesizes the current findings from both preclinical and clinical studies on iNOS across different cancer types, reflecting the variability depending on cellular context and tumor microenvironment. We explore the molecular mechanisms by which iNOS modulates cancer cell growth, survival, and metastasis, emphasizing its impact on immune surveillance and response to treatment. Additionally, the potential of targeting iNOS as a therapeutic strategy in cancer treatment is examined. By integrating insights from recent advances, this review aims to elucidate the significant role of iNOS in cancer and pave the way for novel diagnostic and therapeutic approaches.
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Affiliation(s)
- Tong Chen
- Division of Medical Oncology, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH, 43210, USA; The Ohio State University Comprehensive Cancer Center, Columbus, OH, 43210, USA.
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Kypraios A, Bennour J, Imbert V, David L, Calvo J, Pflumio F, Bonnet R, Couralet M, Magnone V, Lebrigand K, Barbry P, Rohrlich PS, Peyron JF. Identifying Candidate Gene Drivers Associated with Relapse in Pediatric T-Cell Acute Lymphoblastic Leukemia Using a Gene Co-Expression Network Approach. Cancers (Basel) 2024; 16:1667. [PMID: 38730619 PMCID: PMC11083586 DOI: 10.3390/cancers16091667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
Pediatric T-cell Acute Lymphoblastic Leukemia (T-ALL) relapses are still associated with a dismal outcome, justifying the search for new therapeutic targets and relapse biomarkers. Using single-cell RNA sequencing (scRNAseq) data from three paired samples of pediatric T-ALL at diagnosis and relapse, we first conducted a high-dimensional weighted gene co-expression network analysis (hdWGCNA). This analysis highlighted several gene co-expression networks (GCNs) and identified relapse-associated hub genes, which are considered potential driver genes. Shared relapse-expressed genes were found to be related to antigen presentation (HLA, B2M), cytoskeleton remodeling (TUBB, TUBA1B), translation (ribosomal proteins, EIF1, EEF1B2), immune responses (MIF, EMP3), stress responses (UBC, HSP90AB1/AA1), metabolism (FTH1, NME1/2, ARCL4C), and transcriptional remodeling (NF-κB family genes, FOS-JUN, KLF2, or KLF6). We then utilized sparse partial least squares discriminant analysis to select from a pool of 481 unique leukemic hub genes, which are the genes most discriminant between diagnosis and relapse states (comprising 44, 35, and 31 genes, respectively, for each patient). Applying a Cox regression method to these patient-specific genes, along with transcriptomic and clinical data from the TARGET-ALL AALL0434 cohort, we generated three model gene signatures that efficiently identified relapsed patients within the cohort. Overall, our approach identified new potential relapse-associated genes and proposed three model gene signatures associated with lower survival rates for high-score patients.
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Affiliation(s)
- Anthony Kypraios
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Juba Bennour
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Véronique Imbert
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Léa David
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Julien Calvo
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Françoise Pflumio
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Raphaël Bonnet
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
| | - Marie Couralet
- Université de Paris, Inserm, CEA, 92260 Fontenay-aux-Roses, France
- Université Côte d’Azur, CNRS, IPMC, 06560 Valbonne, France; (M.C.); (V.M.); (K.L.)
| | - Virginie Magnone
- Université de Paris, Inserm, CEA, 92260 Fontenay-aux-Roses, France
- Université Côte d’Azur, CNRS, IPMC, 06560 Valbonne, France; (M.C.); (V.M.); (K.L.)
| | - Kevin Lebrigand
- Université de Paris, Inserm, CEA, 92260 Fontenay-aux-Roses, France
- Université Côte d’Azur, CNRS, IPMC, 06560 Valbonne, France; (M.C.); (V.M.); (K.L.)
| | - Pascal Barbry
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
- CHU de Nice, Hôpital de l’Archet, 06000 Nice, France
| | - Pierre S. Rohrlich
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- Team#4: “Fundamental to Translational Research on Dysregulated Hematopoiesis—DysHema”, Centre Méditerranéen de Médecine Moléculaire-C3M-Inserm U1065, Bâtiment Universitaire ARCHIMED, 151 Route Saint Antoine de Ginestière, BP 2 3194, CEDEX 3, 06204 Nice, France
- CHU de Nice, Hôpital de l’Archet, 06000 Nice, France
| | - Jean-François Peyron
- Université Côte d’Azur, Inserm C3M, 06200 Nice, France (V.I.); (L.D.); (R.B.); (P.S.R.)
- CHU de Nice, Hôpital de l’Archet, 06000 Nice, France
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Syafruddin SE, Mohtar MA, Wan Mohamad Nazarie WF, Low TY. Two Sides of the Same Coin: The Roles of KLF6 in Physiology and Pathophysiology. Biomolecules 2020; 10:biom10101378. [PMID: 32998281 PMCID: PMC7601070 DOI: 10.3390/biom10101378] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/26/2020] [Accepted: 09/26/2020] [Indexed: 12/12/2022] Open
Abstract
The Krüppel-like factors (KLFs) family of proteins control several key biological processes that include proliferation, differentiation, metabolism, apoptosis and inflammation. Dysregulation of KLF functions have been shown to disrupt cellular homeostasis and contribute to disease development. KLF6 is a relevant example; a range of functional and expression assays suggested that the dysregulation of KLF6 contributes to the onset of cancer, inflammation-associated diseases as well as cardiovascular diseases. KLF6 expression is either suppressed or elevated depending on the disease, and this is largely due to alternative splicing events producing KLF6 isoforms with specialised functions. Hence, the aim of this review is to discuss the known aspects of KLF6 biology that covers the gene and protein architecture, gene regulation, post-translational modifications and functions of KLF6 in health and diseases. We put special emphasis on the equivocal roles of its full-length and spliced variants. We also deliberate on the therapeutic strategies of KLF6 and its associated signalling pathways. Finally, we provide compelling basic and clinical questions to enhance the knowledge and research on elucidating the roles of KLF6 in physiological and pathophysiological processes.
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Affiliation(s)
- Saiful E. Syafruddin
- UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (M.A.M.); (T.Y.L.)
- Correspondence: ; Tel.: +60-3-9145-9040
| | - M. Aiman Mohtar
- UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (M.A.M.); (T.Y.L.)
| | - Wan Fahmi Wan Mohamad Nazarie
- Biotechnology Programme, Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Kota Kinabalu 88400, Malaysia;
| | - Teck Yew Low
- UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia; (M.A.M.); (T.Y.L.)
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Sabatino ME, Castellaro A, Racca AC, Carbajosa González S, Pansa MF, Soria G, Bocco JL. Krüppel-Like Factor 6 Is Required for Oxidative and Oncogene-Induced Cellular Senescence. Front Cell Dev Biol 2019; 7:297. [PMID: 31824948 PMCID: PMC6882731 DOI: 10.3389/fcell.2019.00297] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 11/07/2019] [Indexed: 12/24/2022] Open
Abstract
Krüppel-like factor 6 (KLF6) is a transcription factor involved in the regulation of several cellular processes. Regarding its role in tumorigenesis, KLF6 is considered a tumor suppressor. Numerous reports demonstrate its frequent genomic loss or down-regulation, implying a functional inactivation in a broad range of human cancers. Previous work from our laboratory showed that the down-regulation of KLF6 expression in normal fibroblasts leads to cellular transformation, while its ectopic expression interferes with the oncogenic transformation triggered by activated Ras through a cell cycle arrest. We hypothesize that the growth suppressor activity of KLF6 may involve the induction of cellular senescence thereby helping to prevent the proliferation of cells at risk of neoplastic transformation. Here, we explored the association of KLF6 up-regulation in two different cellular senescence scenarios. We found that KLF6 silencing bypasses both oxidative and oncogene-induced senescence. In this context, KLF6 expression per se was capable to trigger cellular senescence in both normal and tumoral contexts. As such, the findings presented in this report provide insights into a potential mechanism by which KLF6 may play a suppressing role of uncontrolled or damaged cell proliferation.
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Affiliation(s)
- Maria Eugenia Sabatino
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andrés Castellaro
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Ana C Racca
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Sofía Carbajosa González
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maria Florencia Pansa
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Gastón Soria
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Jose Luis Bocco
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
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5
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Mo X, Chen J, Wang X, Pan Z, Ke Y, Zhou Z, Xie J, Lv G, Luo X. Krüppel-like factor 4 regulates the expression of inducible nitric oxide synthase induced by TNF-α in human fibroblast-like synoviocyte MH7A cells. Mol Cell Biochem 2017; 438:77-84. [PMID: 28744810 DOI: 10.1007/s11010-017-3115-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/15/2017] [Indexed: 12/01/2022]
Abstract
Krüppel-like factor 4 (KLF4), a zinc finger transcription factor, has been implicated in the inflammation mediated by macrophages and endothelial cells by regulating the expression of inflammatory mediators. Here, we investigated whether KLF4 affects the expression of inducible nitric oxide synthase (iNOS), an important inflammatory mediator, in the human RA fibroblast-like synovial cell line MH7A. A pcDNA3.1-KLF4 plasmid or short interfering RNA KLF4 was transfected into MH7A cells, and the iNOS expression and nitric oxide (NO) production were analyzed by quantitative PCR, immunoblotting, and nitrite measurement. The iNOS promoter activity was determined by luciferase assay. The results showed overexpression of KLF4 increased iNOS expression and NO production in the presence or absence of TNF-α. Conversely, KLF4 knockdown markedly reduced iNOS expression and NO production induced by TNF-α. KLF4 activated the transcription activity of iNOS promoter in MH7A cells stimulated by TNF-α. This study indicates that KLF4 is important for regulating the expression of iNOS by TNF-α in human synoviocytes.
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Affiliation(s)
- Xuanrong Mo
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China
| | - Jie Chen
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China
| | - Xinjuan Wang
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China
| | - Zhenyu Pan
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China
| | - Yuping Ke
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China
| | - Zhidong Zhou
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China
| | - Jiangwen Xie
- Department of Cardiology, Yingzhou District Second people's Hospital, Ningbo, 315000, China
| | - Guoju Lv
- Department of Cardiology, Yingzhou District Second people's Hospital, Ningbo, 315000, China
| | - Xinjing Luo
- Department of Basic Medical Sciences, School of Medicine of Taizhou University, Taizhou, 318000, Zhejiang, China.
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Al Drees A, Salah Khalil M, Soliman M. Histological and Immunohistochemical Basis of the Effect of Aminoguanidine on Renal Changes Associated with Hemorrhagic Shock in a Rat Model. Acta Histochem Cytochem 2017; 50:11-19. [PMID: 28386146 PMCID: PMC5374099 DOI: 10.1267/ahc.16025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 12/01/2016] [Indexed: 12/26/2022] Open
Abstract
Acute kidney failure is the main cause of death among patients with severe trauma due to massive blood loss and hemorrhagic shock (HS). Renal cell injury is caused by tissue ischemia. Renal ischemia initiates a complex and interconnected chain of events resulting in cell injury and renal cell necrosis. Nitric oxide plays a crucial role in renal function and can be inhibited by aminoguanidine (AG). We studied whether AG can ameliorate pathological renal changes associated with HS syndrome in a rat model and explored the AG protection mechanism. Rats were intraperitoneally injected with heparin sodium and mean arterial blood pressure was monitored. Animals were divided into three groups: control (without hemorrhage), with or without intra-arterially injected AG; HS (blood continuously withdrawn or reinfused to maintain an MABP of 35-40 mmHg); and HS with AG. We found that AG decreased plasma concentrations of urea, creatinine, and nitrates; ameliorated histological changes of HS-induced rats; and decreased the expressions of inducible nitrogen oxide synthase (iNOS), proapoptotic protein (BAX), and vitamin D receptors (VDR). AG ameliorated kidney injury by inhibiting iNOS resulting in decreased BAX and VDR expressions. Therefore, a therapeutic strategy targeting AG may provide new insights into kidney injury during severe shock.
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Affiliation(s)
- Abdulmajeed Al Drees
- Department of Physiology/Department of Medical Education, College of Medicine, King Saud University
| | - Mahmoud Salah Khalil
- College of Medicine, King Saud University
- Department of Histology, Faculty of Medicine, Suez Canal University
| | - Mona Soliman
- Department of Physiology/Department of Medical Education, College of Medicine, King Saud University
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Gene Co-Expression Network Analysis Unraveling Transcriptional Regulation of High-Altitude Adaptation of Tibetan Pig. PLoS One 2016; 11:e0168161. [PMID: 27936142 PMCID: PMC5148111 DOI: 10.1371/journal.pone.0168161] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/27/2016] [Indexed: 02/08/2023] Open
Abstract
Tibetan pigs have survived at high altitude for millennia and they have a suite of adaptive features to tolerate the hypoxic environment. However, the molecular mechanisms underlying the regulation of hypoxia-adaptive phenotypes have not been completely elucidated. In this study, we analyzed differentially expressed genes (DEGs), biological pathways and constructed co-expression regulation networks using whole-transcriptome microarrays from lung tissues of Tibetan and Duroc pigs both at high and low altitude. A total of 3,066 DEGs were identified and this list was over-represented for the ontology terms including metabolic process, catalytic activity, and KEGG pathway including metabolic pathway and PI3K-Akt signaling pathway. The regulatory (RIF) and phenotypic (PIF) impact factor analysis identified several known and several potentially novel regulators of hypoxia adaption, including: IKBKG, KLF6 and RBPJ (RIF1), SF3B1, EFEMP1, HOXB6 and ATF6 (RIF2). These findings provide new details of the regulatory architecture of hypoxia-adaptive genes and also insight into which genes may undergo epigenetic modification for further study in the high-altitude adaptation.
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Inducible nitric oxide synthase (iNOS) regulatory region variation in non-human primates. INFECTION GENETICS AND EVOLUTION 2015; 31:236-44. [PMID: 25675838 DOI: 10.1016/j.meegid.2015.01.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/07/2015] [Accepted: 01/19/2015] [Indexed: 01/26/2023]
Abstract
Inducible nitric oxide synthase (iNOS) is an enzyme that plays a key role in intracellular immune response against respiratory infections. Since various species of nonhuman primates exhibit different levels of susceptibility to infectious respiratory diseases, and since variation in regulatory regions of genes is thought to play a key role in expression levels of genes, two candidate regulatory regions of iNOS were mapped, sequenced, and compared across five species of nonhuman primates: African green monkeys (Chlorocebus sabaeus), pig-tailed macaques (Macaca nemestrina), cynomolgus macaques (Macaca fascicularis), Indian rhesus macaques (Macaca mulatta), and Chinese rhesus macaques (M. mulatta). In addition, we conducted an in silico analysis of the transcription factor binding sites associated with genetic variation in these two candidate regulatory regions across species. We found that only one of the two candidate regions showed strong evidence of involvement in iNOS regulation. Specifically, we found evidence of 13 conserved binding site candidates linked to iNOS regulation: AP-1, C/EBPB, CREB, GATA-1, GATA-3, NF-AT, NF-AT5, NF-κB, KLF4, Oct-1, PEA3, SMAD3, and TCF11. Additionally, we found evidence of interspecies variation in binding sites for several regulatory elements linked to iNOS (GATA-3, GATA-4, KLF6, SRF, STAT-1, STAT-3, OLF-1 and HIF-1) across species, especially in African green monkeys relative to other species. Given the key role of iNOS in respiratory immune response, the findings of this study might help guide the direction of future studies aimed to uncover the molecular mechanisms underlying the increased susceptibility of African green monkeys to several viral and bacterial respiratory infections.
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Abstract
Pharmacological concentrations of H2S donors inhibit some T cell functions by inhibiting mitochondrial function, but evidence is also emerging that H2S at physiological concentrations produced via chemical sources and endogenously is a positive physiological mediator of T cell function. Expression of the H2S biosynthetic enzymes cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS) is induced in response to T cell receptor signaling. Inhibiting the induction of these enzymes limits T cell activation and proliferation, which can be overcome by exposure to exogenous H2S at submicromolar concentrations. Exogenous H2S at physiological concentrations increases the ability of T cells to form an immunological synapse by altering cytoskeletal actin dynamics and increasing the reorientation of the microtubule-organizing center. Downstream, H2S enhances T cell receptor-dependent induction of CD69, CD25, and Interleukin-2 (IL-2) gene expression. The T cell stimulatory activity of H2S is enhanced under hypoxic conditions that limit its oxidative metabolism by mitochondrial and nonenzymatic processes. Studies of the receptor CD47 have revealed the first endogenous inhibitory signaling pathway that regulates H2S signaling in T cells. Binding of the secreted protein thrombospondin-1 to CD47 elicits signals that block the stimulatory activity of exogenous H2S on T cell activation and limit the induction of CSE and CBS gene expression. CD47 signaling thereby inhibits T cell receptor-mediated T cell activation.
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MiR-181a regulates blood-tumor barrier permeability by targeting Krüppel-like factor 6. J Cereb Blood Flow Metab 2014; 34:1826-36. [PMID: 25182666 PMCID: PMC4269760 DOI: 10.1038/jcbfm.2014.152] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/29/2014] [Accepted: 07/28/2014] [Indexed: 12/18/2022]
Abstract
Blood-tumor barrier (BTB) constitutes an efficient organization of tight junctions that impairs the delivery of therapeutic drugs. However, the methods and molecular mechanisms underlying the BTB opening remain elusive. MicroRNAs (miRNAs) have recently emerged as key regulators of various biologic processes and therapeutic targets. In this study, we have identified microRNA-181a (miR-181a) as a critical miRNA in opening BTB. MicroRNA-181a expression was upregulated in glioma endothelial cells (GECs), which were obtained by coculturing endothelial cells (ECs) with glioma cells. Overexpression of miR-181a resulted in an impaired and permeability increased BTB, and meanwhile reduced the expression of zonula occluden (ZO)-1, occludin, and claudin-5. Kruppel-like factor 6 (KLF6), a transcription factor of the zinc-finger family, was downregulated in GECs. Mechanistic investigations defined it as a direct and functional downstream target of miR-181a, which was involved in the regulation of BTB permeability and the expression of ZO-1, occludin, and claudin-5. Furthermore, luciferase assays and chromatin immunoprecipitation assays showed that KLF6 upregulated the promoter activities and interacted with the promoters of ZO-1, occludin, and claudin-5 in GECs. Collectively, we showed the possibility that overexpression of miR-181a contributes to the increased permeability of BTB by targeting KLF6, thereby revealing potential therapeutic targets for the treatment of brain gliomas.
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Yao YL, Ma J, Wang P, Xue YX, Li Z, Zhao LN, Li ZQ, Feng TD, Liu YH. miR-101 acts as a tumor suppressor by targeting Kruppel-like factor 6 in glioblastoma stem cells. CNS Neurosci Ther 2014; 21:40-51. [PMID: 25230316 DOI: 10.1111/cns.12321] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 07/31/2014] [Accepted: 08/02/2014] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND AIMS Great interest persists in useful therapeutic targets in glioblastoma (GBM). Deregulation of microRNAs (miRNAs) expression has been associated with cancer formation through alterations in gene targets. In this study, we reported the role of miR-101 in human glioblastoma stem cells (GSCs) and the potential mechanisms. METHODS AND RESULTS Quantitative real-time PCR showed that miR-101 expression was decreased in GSCs. Overexpression of miR-101 reduced the proliferation, migration, invasion, and promoted apoptosis of GSCs. One direct target of miR-101, the transcription factor Kruppel-like factor 6 (KLF6), was identified using the Dual-Luciferase Reporter Assay System, which mediated the tumor suppressor activity of miR-101. This process was coincided with the reduced expression of Chitinase-3-like protein 1 (CHI3L1) whose promoter could be bound with and be promoted by KLF6 demonstrated by luciferase assays and chromatin immunoprecipitation assays. The downregulation of CHI3L1 led to the inactivation of MEK1/2 and PI3K signal pathways. Furthermore, nude mice carrying the tumors of overexpressed miR-101 combined with knockdown of KLF6 produced the smallest tumors and showed the highest survival rate. CONCLUSIONS Our findings provided a comprehensive analysis of miR-101 and further defining it as a potential therapeutic candidate for GBM.
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Affiliation(s)
- Yi-Long Yao
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, China
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12
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Ollila HM, Kettunen J, Pietiläinen O, Aho V, Silander K, Kronholm E, Perola M, Lahti J, Räikkönen K, Widen E, Palotie A, Eriksson JG, Partonen T, Kaprio J, Salomaa V, Raitakari O, Lehtimäki T, Sallinen M, Härmä M, Porkka-Heiskanen T, Paunio T. Genome-wide association study of sleep duration in the Finnish population. J Sleep Res 2014; 23:609-618. [PMID: 25109461 DOI: 10.1111/jsr.12175] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/10/2014] [Indexed: 12/19/2022]
Abstract
Sleep duration is genetically regulated, but the genetic variants are largely unknown. We aimed to identify such genes using a genome-wide association study (GWAS) combined with RNA expression at the population level, and with experimental verification. A GWAS was performed in a Finnish sample (n = 1941), and variants with suggestive association (P < 5 × 10(-5) ) were tested in a follow-up sample from the same population with sleep duration (n = 6834) and time in bed (n = 1720). Variants with pointwise association of P < 0.05 in the follow-up sample were analysed further. First, we correlated genotypes with transcript expression levels with sleep duration (n = 207). The expression levels of significant transcripts were further studied in experimental sleep restriction. Of the 31 variants with P < 5 × 10(-5) in the discovery sample, three variants showed nominal allelic association (P < 0.05) in the follow-up sample: rs10914351, near PTPRU (P = 0.049), rs1037079 in PCDH7-CENTD1 (P = 0.011) and rs2031573 near KLF6 (P = 0.044). The risk alleles for shorter sleep (rs2031573 and rs1037079) were also associated with higher KLF6 and PCDH7 expression levels (P < 0.05). Experimental sleep restriction increased the expression of KLF6 (P < 0.01). These data suggest that rs2031573 near KLF6 or related loci and rs1037079 between PCDH7-CENTD1 or related loci may contribute to the regulation of sleep duration via gene expression. These results illustrate the utility of combining different analytical approaches to identify genetic determinants for traits related to sleep physiology. However, additional studies are needed in order to understand the roles of KLF6 and PCDH7 in sleep regulation.
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Affiliation(s)
- Hanna M Ollila
- Public Health Genomics Unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland.,Institute of Biomedicine, Physiology, University of Helsinki, Helsinki, Finland.,Department of Psychiatry, University of Helsinki, Helsinki, Finland
| | - Johannes Kettunen
- Public Health Genomics Unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
| | - Olli Pietiläinen
- Public Health Genomics Unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland.,The Wellcome Trust Sanger Institute, Cambridge, UK
| | - Vilma Aho
- Institute of Biomedicine, Physiology, University of Helsinki, Helsinki, Finland
| | - Kaisa Silander
- Public Health Genomics Unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
| | - Erkki Kronholm
- Population Studies Unit, Department of Chronic Disease Prevention, National Institute for Health and Welfare, Turku, Finland
| | - Markus Perola
- Public Health Genomics Unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
| | - Jari Lahti
- Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland.,Folkhälsan Research Centre, Helsinki, Finland
| | - Katri Räikkönen
- Institute of Behavioural Sciences, University of Helsinki, Helsinki, Finland.,Folkhälsan Research Centre, Helsinki, Finland
| | - Elisabeth Widen
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland
| | - Aarno Palotie
- Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.,Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute, Cambridge, MA, USA.,Psychiatric and Neurodevelopmental Genetics Unit, Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - Johan G Eriksson
- Folkhälsan Research Centre, Helsinki, Finland.,Unit of General Practice, Helsinki University Central Hospital, Helsinki, Finland.,Vasa Central Hospital, Vasa, Finland
| | - Timo Partonen
- Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland
| | - Jaakko Kaprio
- Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland.,Department of Public Health, Hjelt Institute University of Helsinki, Helsinki, Finland
| | - Veikko Salomaa
- Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
| | - Olli Raitakari
- Research Centre of Applied and Preventive Cardiovascular Medicine and the Department of Clinical Physiology and Nuclear Medicine, University of Turku and Turku University Hospital, Turku, Finland
| | - Terho Lehtimäki
- Department of Clinical Chemistry, Fimlab Laboratories and Tampere University School of Medicine, Tampere, Finland
| | - Mikael Sallinen
- Working Hours, Alertness and Professional Traffic Team, Finnish Institute of Occupational Health, Helsinki, Finland
| | - Mikko Härmä
- Working Hours, Alertness and Professional Traffic Team, Finnish Institute of Occupational Health, Helsinki, Finland
| | | | - Tiina Paunio
- Public Health Genomics Unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland.,Department of Psychiatry, University of Helsinki, Helsinki, Finland
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13
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The impact of simvastatin on pulmonary effectors of Pseudomonas aeruginosa infection. PLoS One 2014; 9:e102200. [PMID: 25010049 PMCID: PMC4092124 DOI: 10.1371/journal.pone.0102200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 06/16/2014] [Indexed: 12/22/2022] Open
Abstract
The statin family of cholesterol-lowering drugs is known to have pleiotropic properties which include anti-inflammatory and immunomodulatory effects. Statins exert their pleiotropic effects by altering expression of human immune regulators including pro-inflammatory cytokines. Previously we found that statins modulate virulence phenotypes of the human pathogen Pseudomonas aeruginosa, and sought to investigate if simvastatin could alter the host response to this organism in lung epithelial cells. Simvastatin increased the expression of the P. aeruginosa target genes KLF2, KLF6, IL-8 and CCL20. Furthermore, both simvastatin and P. aeruginosa induced alternative splicing of KLF6. The novel effect of simvastatin on wtKLF6 expression was found to be responsible for induction of the KLF6 regulated genes CCL20 and iNOS. Simvastatin also increased the adhesion of P. aeruginosa to host cells, without altering invasion or cytotoxicity. This study demonstrated that simvastatin had several novel effects on the pulmonary cellular immune response.
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14
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Gui T, Wang Y, Zhang L, Wang W, Zhu H, Ding W. Krüppel-like factor 6 rendered rat Schwann cell more sensitive to apoptosis via upregulating FAS expression. PLoS One 2013; 8:e82449. [PMID: 24324791 PMCID: PMC3853331 DOI: 10.1371/journal.pone.0082449] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/02/2013] [Indexed: 12/12/2022] Open
Abstract
Krüppel-like factor 6 (KLF6) is a tumor suppressor gene and play a role in the regulation of cell proliferation and apoptosis. After the peripheral nerve injury (PNI), the microenvironment created by surrounding Schwann cells (SCs) is a critical determinant of its regenerative potential. In this study, we examined the effects of KLF6 on SCs responses during PNI. Both KLF6 mRNA and protein expression levels were upregulated in the injured sciatic nerve, and immunofluorescence results showed that many KLF6-positive cells simultaneously expressed the SC markers S-100 and p75NTR. The apoptosis inducers TNFα and cisplatin upregulated KLF6 expression in primary cultured SCs and the SC line RSC96. Although KLF6 overexpression exacerbated cisplatin- and TNFα-induced apoptosis, expression levels of the apoptosis regulators Bcl2 and Bax were not significantly affected in either KLF6-overexpressing or KLF6-depleted RSC96 cells. Realtime PCR arrays and qRT-PCR demonstrated that KLF6 overexpression upregulated four pro-apoptotic genes, FAS, TNF, TNFSF12, and PYCARD, and inhibited expression of the anti-apoptotic IL10 gene expression. Further analysis revealed that FAS protein expression was positively correlated with KLF6 expression in SCs. These data suggest that KLF6 upregulation may render SCs more vulnerable to apoptosis after injury via upregulating FAS expression.
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Affiliation(s)
- Ting Gui
- Department of Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yueming Wang
- Department of Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lixing Zhang
- State Key Laboratrory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenjing Wang
- Department of Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hao Zhu
- Department of Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenlong Ding
- Department of Anatomy, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail:
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15
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Palau N, Julià A, Ferrándiz C, Puig L, Fonseca E, Fernández E, López-Lasanta M, Tortosa R, Marsal S. Genome-wide transcriptional analysis of T cell activation reveals differential gene expression associated with psoriasis. BMC Genomics 2013; 14:825. [PMID: 24267790 PMCID: PMC4046651 DOI: 10.1186/1471-2164-14-825] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 11/19/2013] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Psoriasis is a chronic autoimmune disease in which T cells have a predominant role in initiating and perpetuating the chronic inflammation in skin. However, the mechanisms that regulate T cell activation in psoriasis are still incompletely understood. The objective of the present study was to characterize the main genetic pathways associated with T cell activation in psoriasis. RESULTS Gene expression profiles from in vitro activated T cells were obtained from 17 psoriasis patients and 7 healthy controls using Illumina HT-12 v4 microarrays. From a total of 47,321 analyzed transcripts, 42 genes were found to be differentially expressed between psoriasis and controls (FDR p-value < 0.1, absolute fold-change > 1.2). Using an independent cohort of 8 patients and 8 healthy controls we validated the overexpression of SPATS2L (p-value =0.0009) and KLF6 (p-value =0.0012) genes in activated T cells from psoriasis patients. Using weighted correlation analysis we identified SPATS2L and KLF6 coexpression networks, which were also significantly associated with psoriasis (p-value < 0.05). Gene Ontology analysis allowed the identification of several biological processes associated with each coexpression network. Finally, using Gene Set Enrichment Analysis over the global T cell transcriptome we also found additional genetic pathways strongly associated with psoriasis (p-value < 0.0001). CONCLUSIONS This study has identified two new genes, SPATS2L and KLF6, strongly associated with T cell activation in psoriasis. Functional analyses of the gene expression profiles also revealed new biological processes and genetic pathways associated with psoriasis. The results of this study provide an important insight into the biology of this common chronic inflammatory disease.
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Affiliation(s)
- Nuria Palau
- Rheumatology Research Group, Vall d'Hebron Research Institute, Barcelona 08035, Spain.
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16
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Lang UE, Kocabayoglu P, Cheng GZ, Ghiassi-Nejad Z, Muñoz U, Vetter D, Eckstein DA, Hannivoort RA, Walsh MJ, Friedman SL. GSK3β phosphorylation of the KLF6 tumor suppressor promotes its transactivation of p21. Oncogene 2013; 32:4557-64. [PMID: 23085750 PMCID: PMC3892988 DOI: 10.1038/onc.2012.457] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 07/26/2012] [Accepted: 08/13/2012] [Indexed: 12/24/2022]
Abstract
KLF6, a ubiquitously expressed Krüppel-like transcription factor, is frequently inactivated in human cancer and has significant roles in cellular proliferation, apoptosis, differentiation and development. A key mechanism of KLF6-mediated growth suppression is through p53-independent transactivation of p21. Several cancer-derived KLF6 mutants lead to the loss of p21-mediated growth suppression through an unknown mechanism. Because several colorectal cancer and hepatocellular carcinoma-derived KLF6 mutations affect a glycogen synthase kinase 3β (GSK3β) phosphorylation consensus site, we investigated the role of GSK3β in the regulation of KLF6 function. Based on transient transfection, GSK3β augments the transactivation of a p21 promoter luciferase by KLF6. Reciprocal co-immunoprecipitation of hemagglutinin (HA)-GSK3β and Flag-KLF6 validated the interaction between these two proteins. KLF6 phosphorylation is augmented in the presence of GSK3β based on in vitro and in vivo (32)P incorporation assays. Site-directed mutagenesis of the candidate phosphorylation sites to alanines ('KLF6-4A' phosphomutant) eliminated a higher molecular weight phosphorylated isoform of KLF6 based on western blot. GSK3β augmented the transactivation by wild-type KLF6, but not KLF6-4A, towards the p21 promoter, and increased p21 protein. Functionally, GSK3β enhanced KLF6-mediated growth suppression, which was abrogated by the KLF6-4A phosphomutant. These data establish that GSK3β directly phosphorylates KLF6, which augments its induction of p21 and resultant growth suppression. This interaction may account for the growth-promoting effects of cancer-derived KLF6 mutants that lack tumor suppressor activity.
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Affiliation(s)
- UE Lang
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - P Kocabayoglu
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - GZ Cheng
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - Z Ghiassi-Nejad
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - U Muñoz
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - D Vetter
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - DA Eckstein
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - RA Hannivoort
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
| | - MJ Walsh
- Departments of Structural and Chemical Biology, Pediatrics, and Genetic and Genomic Sciences, Mount Sinai School of Medicine, New York, NY, USA
| | - SL Friedman
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA
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17
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Mgbemena V, Segovia J, Chang TH, Bose S. KLF6 and iNOS regulates apoptosis during respiratory syncytial virus infection. Cell Immunol 2013; 283:1-7. [PMID: 23831683 DOI: 10.1016/j.cellimm.2013.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 05/24/2013] [Accepted: 06/05/2013] [Indexed: 01/01/2023]
Abstract
Human respiratory syncytial virus (RSV) is a highly pathogenic lung-tropic virus that causes severe respiratory diseases. Enzymatic activity of inducible nitric oxide (iNOS) is required for NO generation. Although NO contributes to exaggerated lung disease during RSV infection, the role of NO in apoptosis during infection is not known. In addition, host trans-activator(s) required for iNOS gene expression during RSV infection is unknown. In the current study we have uncovered the mechanism of iNOS gene induction by identifying kruppel-like factor 6 (KLF6) as a critical transcription factor required for iNOS gene expression during RSV infection. Furthermore, we have also uncovered the role of iNOS as a critical host factor regulating apoptosis during RSV infection.
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Affiliation(s)
- Victoria Mgbemena
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, United States
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18
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Patel NM, Kawut SM, Jelic S, Arcasoy SM, Lederer DJ, Borczuk AC. Pulmonary arteriole gene expression signature in idiopathic pulmonary fibrosis. Eur Respir J 2013; 41:1324-30. [PMID: 23728404 PMCID: PMC4720265 DOI: 10.1183/09031936.00084112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A third of patients with idiopathic pulmonary fibrosis (IPF) develop pulmonary hypertension (PH-IPF), which is associated with increased mortality. Whether an altered gene expression profile in the pulmonary vasculature precedes the clinical onset of PH-IPF is unknown. We compared gene expression in the pulmonary vasculature of IPF patients with and without PH with controls. Pulmonary arterioles were isolated using laser capture microdissection from 16 IPF patients: eight with PH (PH-IPF) and eight with no PH (NPH-IPF), and seven controls. Probe was prepared from extracted RNA, and hybridised to Affymetrix Hu133 2.0 Plus genechips. Biometric Research Branch array tools and Ingenuity Pathway Analysis software were used for analysis of the microarray data. Univariate analysis revealed 255 genes that distinguished IPF arterioles from controls (p<0.001). Mediators of vascular smooth muscle and endothelial cell proliferation, Wnt signalling and apoptosis were differentially expressed in IPF arterioles. Unsupervised and supervised clustering analyses revealed similar gene expression in PH-IPF and NPH-IPF arterioles. The pulmonary arteriolar gene expression profile is similar in IPF patients with and without coexistent PH. Pathways involved in vascular proliferation and aberrant apoptosis, which may contribute to pulmonary vascular remodelling, are activated in IPF patients.
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Affiliation(s)
- Nina M. Patel
- Division of Pulmonary, Allergy and Critical Care Medicine, Columbia University, New York, NY, USA,Interstitial Lung Disease Program, New York Presbyterian Hospital, New York, NY, USA
| | - Steven M. Kawut
- Dept of Medicine and the Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sanja Jelic
- Division of Pulmonary, Allergy and Critical Care Medicine, Columbia University, New York, NY, USA
| | - Selim M. Arcasoy
- Division of Pulmonary, Allergy and Critical Care Medicine, Columbia University, New York, NY, USA,Interstitial Lung Disease Program, New York Presbyterian Hospital, New York, NY, USA,Lung Transplantation Program, New York Presbyterian Hospital, New York, NY, USA
| | - David J. Lederer
- Division of Pulmonary, Allergy and Critical Care Medicine, Columbia University, New York, NY, USA,Interstitial Lung Disease Program, New York Presbyterian Hospital, New York, NY, USA,Lung Transplantation Program, New York Presbyterian Hospital, New York, NY, USA
| | - Alain C. Borczuk
- Dept of Pathology and Cell Biology, Columbia University, New York, NY, USA
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19
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Wilson SR, Joshi AD, Elferink CJ. The tumor suppressor Kruppel-like factor 6 is a novel aryl hydrocarbon receptor DNA binding partner. J Pharmacol Exp Ther 2013; 345:419-29. [PMID: 23512538 DOI: 10.1124/jpet.113.203786] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-mediated basic helix-loop-helix transcription factor of the Per/Arnt/Sim family that regulates adaptive and toxic responses to a variety of chemical pollutants, including polycyclic aromatic hydrocarbons and halogenated aromatic hydrocarbons, most notably 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Ligand activation leads to AhR nuclear translocation and binding to a xenobiotic response element (XRE) in association with the Arnt to regulate gene expression. Several recent genome-wide transcriptional studies identified numerous AhR target genes that lack the canonical XRE recognition site in the promoter regions. Characterization of one such target gene, the plasminogen activator inhibitor 1, identified a novel nonconsensus XRE (NC-XRE) that confers TCDD responsiveness independently of the Arnt protein. Studies reported here show that the NC-XRE is a recognition site for the AhR and a new binding partner, the Kruppel-like factor (KLF) family member KLF6. In vivo chromatin immunoprecipitations and in vitro DNA binding studies demonstrate that the AhR and KLF6 proteins form an obligatory heterodimer necessary for NC-XRE binding. Mutational analyses show that the protein-protein interactions involve the AhR C terminus and KLF6 N terminus, respectively. Moreover, NC-XRE binding depends on the 5' basic region in KLF6 rather than the previously characterized zinc finger DNA binding domain. Collectively, the results unmask a novel AhR signaling mechanism distinct from the canonical XRE-driven process that will enrich our future understanding of AhR biology.
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Affiliation(s)
- Shelly R Wilson
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
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20
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Abstract
KLF6, a ubiquitously expressed Krüppel-like transcription factor, is frequently inactivated in human cancer and has significant roles in cellular proliferation, apoptosis, differentiation and development. A key mechanism of KLF6-mediated growth suppression is through p53-independent transactivation of p21. Several cancer-derived KLF6 mutants lead to the loss of p21-mediated growth suppression through an unknown mechanism. Because several colorectal cancer and hepatocellular carcinoma-derived KLF6 mutations affect a glycogen synthase kinase 3β (GSK3β) phosphorylation consensus site, we investigated the role of GSK3β in the regulation of KLF6 function. Based on transient transfection, GSK3β augments the transactivation of a p21 promoter luciferase by KLF6. Reciprocal co-immunoprecipitation of hemagglutinin (HA)-GSK3β and Flag-KLF6 validated the interaction between these two proteins. KLF6 phosphorylation is augmented in the presence of GSK3β based on in vitro and in vivo (32)P incorporation assays. Site-directed mutagenesis of the candidate phosphorylation sites to alanines ('KLF6-4A' phosphomutant) eliminated a higher molecular weight phosphorylated isoform of KLF6 based on western blot. GSK3β augmented the transactivation by wild-type KLF6, but not KLF6-4A, towards the p21 promoter, and increased p21 protein. Functionally, GSK3β enhanced KLF6-mediated growth suppression, which was abrogated by the KLF6-4A phosphomutant. These data establish that GSK3β directly phosphorylates KLF6, which augments its induction of p21 and resultant growth suppression. This interaction may account for the growth-promoting effects of cancer-derived KLF6 mutants that lack tumor suppressor activity.
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21
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Mgbemena V, Segovia JA, Chang TH, Tsai SY, Cole GT, Hung CY, Bose S. Transactivation of inducible nitric oxide synthase gene by Kruppel-like factor 6 regulates apoptosis during influenza A virus infection. THE JOURNAL OF IMMUNOLOGY 2012; 189:606-15. [PMID: 22711891 DOI: 10.4049/jimmunol.1102742] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Influenza A virus (flu) is a respiratory tract pathogen causing high morbidity and mortality among the human population. NO is a cellular mediator involved in tissue damage through its apoptosis of target cells and resulting enhancement of local inflammation. Inducible NO synthase (iNOS) is involved in the production of NO following infection. Although NO is a key player in the development of exaggerated lung disease during flu infection, the underlying mechanism, including the role of NO in apoptosis during infection, has not been reported. Similarly, the mechanism of iNOS gene induction during flu infection is not well defined in terms of the host transactivator(s) required for iNOS gene expression. In the current study, we identified Kruppel-like factor 6 (KLF6) as a critical transcription factor essential for iNOS gene expression during flu infection. We also underscored the requirement for iNOS in inducing apoptosis during infection. KLF6 gene silencing in human lung epithelial cells resulted in the drastic loss of NO production, iNOS promoter-specific luciferase activity, and expression of iNOS mRNA following flu infection. Chromatin immunoprecipitation assay revealed a direct interaction of KLF6 with iNOS promoter during in vitro and in vivo flu infection of human lung cells and mouse respiratory tract, respectively. A significant reduction in flu-mediated apoptosis was noted in KLF6-silenced cells, cells treated with iNOS inhibitor, and primary murine macrophages derived from iNOS knockout mice. A similar reduction in apoptosis was noted in the lungs following intratracheal flu infection of iNOS knockout mice.
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Affiliation(s)
- Victoria Mgbemena
- Department of Microbiology and Immunology, The University of Texas Health Science Center, San Antonio, TX 78229, USA
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22
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Guo Z, Shao L, Zheng L, Du Q, Li P, John B, Geller DA. miRNA-939 regulates human inducible nitric oxide synthase posttranscriptional gene expression in human hepatocytes. Proc Natl Acad Sci U S A 2012; 109:5826-31. [PMID: 22451906 PMCID: PMC3326458 DOI: 10.1073/pnas.1118118109] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Human inducible nitric oxide synthase (hiNOS) gene expression is regulated by transcriptional and posttranscriptional mechanisms. The purpose of this study was to determine whether specific microRNA (miRNA) directly regulate hiNOS gene expression. Sequence analysis of the 496-bp hiNOS 3'-untranslated region (3'-UTR) revealed five putative miR-939 binding sites. The hiNOS 3'-UTR conferred significant posttranscriptional blockade of luciferase activity in human A549, HCT8, and HeLa cells. The hiNOS 3'-UTR also exerted basal and cytokine-stimulated posttranscriptional repression in an orientation-dependent manner. Functional studies demonstrated that transfection of miR-939 into primary human hepatocytes (HCs) significantly inhibited cytokine-induced NO synthesis in a dose-dependent manner that was abrogated by a specific miR-939 inhibitor. MiR-939 (but not other miRNAs) abolished cytokine-stimulated hiNOS protein in human HC, but had no effect on hiNOS mRNA levels. Site-directed mutagenesis of miR-939 bindings sites at +99 or +112 bp in the hiNOS 3'-UTR increased reporter gene expression. Furthermore, intact miR-939 binding sites at +99 or +112 positions were required for posttranscriptional suppression by miR-939. Cytokine stimulation directly increased miR-939 levels in human HC. Transfection of miR-939 inhibitor (antisense miR-939) enhanced cytokine-induced hiNOS protein and increased NO synthesis in vitro in human HC. Finally, cytokine or LPS injection in vivo in mice increased hepatic miR-939 levels. Taken together, these data identify that miR-939 directly regulates hiNOS gene expression by binding in the 3'-UTR to produce a translational blockade. These findings suggest dual regulation of iNOS gene expression where cytokines induce iNOS transcription and also increase miR-939, leading to translational inhibition in a check-and-balance system.
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Affiliation(s)
| | | | - Liang Zheng
- Computational Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | | | | | - Bino John
- Computational Biology, University of Pittsburgh, Pittsburgh, PA 15261
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23
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Xu K, Zhou Y, Qiu W, Liu X, Xia M, Liu L, Liu X, Zhao D, Wang Y. Activating transcription factor 3 (ATF3) promotes sublytic C5b-9-induced glomerular mesangial cells apoptosis through up-regulation of Gadd45α and KLF6 gene expression. Immunobiology 2011; 216:871-81. [DOI: 10.1016/j.imbio.2011.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/13/2011] [Accepted: 02/15/2011] [Indexed: 01/08/2023]
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A Novel Mechanism of PPARgamma Regulation of TGFbeta1: Implication in Cancer Biology. PPAR Res 2011; 2008:762398. [PMID: 18615188 PMCID: PMC2443397 DOI: 10.1155/2008/762398] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 04/28/2008] [Accepted: 06/09/2008] [Indexed: 02/08/2023] Open
Abstract
Peroxisome proliferator-activated receptor-γ (PPARγ) and retinoic acid X-receptor (RXR) heterodimer, which regulates cell growth and differentiation, represses the TGFβ1 gene that encodes for the protein involved in cancer biology. This review will introduce the novel mechanism associated with the inhibition of the TGFβ1 gene by PPARγ activation, which regulates the dephosphorylation of Zf9 transcription factor. Pharmacological manipulation of TGFβ1 by PPARγ activators can be applied for treating TGFβ1-induced pathophysiologic disorders such as cancer metastasis and fibrosis. In this article, we will discuss the opposing effects of TGFβ on tumor growth and metastasis, and address the signaling pathways regulated by PPARγ for tumor progression and suppression.
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Ratovitski EA. ΔNp63α/IRF6 interplay activates NOS2 transcription and induces autophagy upon tobacco exposure. Arch Biochem Biophys 2011; 506:208-15. [PMID: 21129360 DOI: 10.1016/j.abb.2010.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 11/05/2010] [Accepted: 11/24/2010] [Indexed: 12/31/2022]
Abstract
Tobacco-induced oxidative stress leads to chronic inflammation and is implicated in the development of many human epithelial cancers, including head and neck cancer. Cigarette smoke exposure was shown to induce the expression of the ΔNp63α and nitric oxide synthase (NOS)-2 in head and neck squamous cell carcinoma cells and immortalized oral keratinocytes. The NOS2 promoter was found to contain various cognate sequences for several transcription factors including interferon regulatory factor (IRF)-6 and p63, which were shown in vivo binding to the NOS2 promoter in response to smoke exposure. Small interfering (si)-RNAs against both ΔNp63α and IRF6 decreased the induction of NOS2 promoter-driven reporter luciferase activity and were shown to inhibit NOS2 activity. Furthermore, both mainstream (MSE) and sidestream (SSE) smoking extracts induced changes in expression of autophagic marker, LC3B, while siRNA against ΔNp63α, IRF6 and NOS2 modulated these autophagic changes. Overall, these data support the notion that ΔNp63α/IRF6 interplay regulates NOS2 transcription, thereby underlying the autophagic-related cancer cell response to tobacco exposure.
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Affiliation(s)
- Edward A Ratovitski
- Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
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Abstract
The Krüppel-like transcription factor (KLF) family participates in diverse aspects of cellular growth, development, differentiation, and activation. Recently, several groups have identified new connections between the function of these factors and leukocyte responses in health and disease. Gene targeting of individual KLFs in mice has uncovered novel and unexpected physiologic roles among myeloid and lymphocyte cell lineage maturation, particularly in the bone marrow niche and blood. In addition, several KLF family members are downstream targets of stimuli and signaling pathways critical to T-cell trafficking, T regulatory cell differentiation or suppressor function, monocyte/macrophage activation or renewal, and B memory cell maturation or activation. Indeed, KLFs have been implicated in subtypes of leukemia, lymphoma, autoimmunity, and in acute and chronic inflammatory disease states, such as atherosclerosis, diabetes, and airway inflammation, raising the possibility that KLFs and their upstream signals are of therapeutic interest. This review focuses on the relevant literature of Krüppel-like factors in leukocyte biology and their implications in clinical settings.
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Pautz A, Art J, Hahn S, Nowag S, Voss C, Kleinert H. Regulation of the expression of inducible nitric oxide synthase. Nitric Oxide 2010; 23:75-93. [PMID: 20438856 DOI: 10.1016/j.niox.2010.04.007] [Citation(s) in RCA: 378] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 04/23/2010] [Indexed: 12/13/2022]
Abstract
Nitric oxide (NO) generated by the inducible isoform of nitric oxide synthase (iNOS) is involved in complex immunomodulatory and antitumoral mechanisms and has been described to have multiple beneficial microbicidal, antiviral and antiparasital effects. However, dysfunctional induction of iNOS expression seems to be involved in the pathophysiology of several human diseases. Therefore iNOS has to be regulated very tightly. Modulation of expression, on both the transcriptional and post-transcriptional level, is the major regulation mechanism for iNOS. Pathways resulting in the induction of iNOS expression vary in different cells or species. Activation of the transcription factors NF-kappaB and STAT-1alpha and thereby activation of the iNOS promoter seems to be an essential step for the iNOS induction in most human cells. However, at least in the human system, also post-transcriptional mechanisms involving a complex network of RNA-binding proteins build up by AUF1, HuR, KSRP, PTB and TTP is critically involved in the regulation of iNOS expression. Recent data also implicate regulation of iNOS expression by non-coding RNAs (ncRNAs).
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Affiliation(s)
- Andrea Pautz
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, D-55101 Mainz, Germany
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Correlations between gene expression and mercury levels in blood of boys with and without autism. Neurotox Res 2009; 19:31-48. [PMID: 19937285 PMCID: PMC3006666 DOI: 10.1007/s12640-009-9137-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 10/15/2009] [Accepted: 11/10/2009] [Indexed: 01/23/2023]
Abstract
Gene expression in blood was correlated with mercury levels in blood of 2- to 5-year-old boys with autism (AU) compared to age-matched typically developing (TD) control boys. This was done to address the possibility that the two groups might metabolize toxicants, such as mercury, differently. RNA was isolated from blood and gene expression assessed on whole genome Affymetrix Human U133 expression microarrays. Mercury levels were measured using an inductively coupled plasma mass spectrometer. Analysis of covariance (ANCOVA) was performed and partial correlations between gene expression and mercury levels were calculated, after correcting for age and batch effects. To reduce false positives, only genes shared by the ANCOVA models were analyzed. Of the 26 genes that correlated with mercury levels in both AU and TD boys, 11 were significantly different between the groups (P(Diagnosis*Mercury) ≤ 0.05). The expression of a large number of genes (n = 316) correlated with mercury levels in TD but not in AU boys (P ≤ 0.05), the most represented biological functions being cell death and cell morphology. Expression of 189 genes correlated with mercury levels in AU but not in TD boys (P ≤ 0.05), the most represented biological functions being cell morphology, amino acid metabolism, and antigen presentation. These data and those in our companion study on correlation of gene expression and lead levels show that AU and TD children display different correlations between transcript levels and low levels of mercury and lead. These findings might suggest different genetic transcriptional programs associated with mercury in AU compared to TD children.
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Cao Z, Wara AK, Icli B, Sun X, Packard RRS, Esen F, Stapleton CJ, Subramaniam M, Kretschmer K, Apostolou I, von Boehmer H, Hansson GK, Spelsberg TC, Libby P, Feinberg MW. Kruppel-like factor KLF10 targets transforming growth factor-beta1 to regulate CD4(+)CD25(-) T cells and T regulatory cells. J Biol Chem 2009; 284:24914-24. [PMID: 19602726 DOI: 10.1074/jbc.m109.000059] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD4(+)CD25(+) regulatory T cells (T regs) play a major role in the maintenance of self-tolerance and immune suppression, although the mechanisms controlling T reg development and suppressor function remain incompletely understood. Herein, we provide evidence that Kruppel-like factor 10 (KLF10/TIEG1) constitutes an important regulator of T regulatory cell suppressor function and CD4(+)CD25(-) T cell activation through distinct mechanisms involving transforming growth factor (TGF)-beta1 and Foxp3. KLF10 overexpressing CD4(+)CD25(-) T cells induced both TGF-beta1 and Foxp3 expression, an effect associated with reduced T-Bet (Th1 marker) and Gata3 (Th2 marker) mRNA expression. Consistently, KLF10(-/-) CD4(+)CD25(-) T cells have enhanced differentiation along both Th1 and Th2 pathways and elaborate higher levels of Th1 and Th2 cytokines. Furthermore, KLF10(-/-) CD4(+)CD25(-) T cell effectors cannot be appropriately suppressed by wild-type T regs. Surprisingly, KLF10(-/-) T reg cells have reduced suppressor function, independent of Foxp3 expression, with decreased expression and elaboration of TGF-beta1, an effect completely rescued by exogenous treatment with TGF-beta1. Mechanistic studies demonstrate that in response to TGF-beta1, KLF10 can transactivate both TGF-beta1 and Foxp3 promoters, implicating KLF10 in a positive feedback loop that may promote cell-intrinsic control of T cell activation. Finally, KLF10(-/-) CD4(+)CD25(-) T cells promoted atherosclerosis by approximately 2-fold in ApoE(-/-)/scid/scid mice with increased leukocyte accumulation and peripheral pro-inflammatory cytokines. Thus, KLF10 is a critical regulator in the transcriptional network controlling TGF-beta1 in both CD4(+)CD25(-) T cells and T regs and plays an important role in regulating atherosclerotic lesion formation in mice.
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Affiliation(s)
- Zhuoxiao Cao
- Department of Medicine, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Choy JC, Yi T, Rao DA, Tellides G, Fox-Talbot K, Baldwin WM, Pober JS. CXCL12 induction of inducible nitric oxide synthase in human CD8 T cells. J Heart Lung Transplant 2009; 27:1333-9. [PMID: 19059114 DOI: 10.1016/j.healun.2008.08.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 08/20/2008] [Accepted: 08/26/2008] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND We reported previously that inducible nitric oxide synthase (iNOS) expression in graft-infiltrating human T cells that is confined to the bystander population contributes to T- cell-mediated rejection of allograft arteries in a humanized mouse model. Herein we examine whether CXCL12, a chemokine thought to contribute to recruitment of bystander T cells, induces iNOS in human CD8 T cells. METHODS Human CD8 T cells were treated with CXCL12 and iNOS expression was examined. Also, human allograft arteries were immunohistochemically stained for iNOS and CD8, and adjacent sections stained for CXCL12 to determine their localization in human tissues. RESULTS Resting human CD8 and CD4 T cells expressed the CXCR4, but not the CXCR7, receptor for CXCL12. Treatment with CXCL12 induced expression of both iNOS mRNA and protein in primary human CD8 T cells in a dose-dependent manner, but had no effect on CD4 T cells. Induction of iNOS expression in CD8 T cells was mediated by increased gene transcription. T-cell-receptor (TCR)-activated CD8 T cells rapidly downregulated CXCR4, which coincided with diminished ability of CXCL12 to induce iNOS in activated T cells. iNOS expression in infiltrating human CD8 T cells was spatially associated with CXCL12 expression both in the humanized mouse model of allograft artery rejection and in clinical specimens of coronary arteries displaying allograft vasculopathy. CONCLUSIONS CXCL12 induces iNOS expression in human CD8 T cells and this response may contribute to allograft rejection.
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Affiliation(s)
- Jonathan C Choy
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520-8089, USA
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Jeong KH, Kim SK, Kim SY, Cho KO. Immunohistochemical localization of Krüppel-like factor 6 in the mouse forebrain. Neurosci Lett 2009; 453:16-20. [PMID: 19429007 DOI: 10.1016/j.neulet.2009.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 01/31/2009] [Accepted: 02/02/2009] [Indexed: 10/21/2022]
Abstract
Krüppel-like factor 6 (KLF6) is a transcriptional regulator that shows widespread distribution in the peripheral organs of the body. However, it remains uncertain where KLF6 is expressed in the adult forebrain under physiological conditions. Therefore, the present study investigated the spatial patterns of KLF6 expression and identified cell types expressing KLF6 in the forebrain. KLF6 immunoreactivity was widely seen throughout the forebrain including the olfactory bulb, cerebral cortex, hippocampus, septum, amygdala, basal ganglia, thalamus, and hypothalamus. Moreover, KLF6-positive cells were also detected in the radial migratory stream (RMS) and subventricular zone. Immunofluorescent double-labeling revealed that KLF6-immunoreactive cells were co-localized with neuronal nuclei or platelet endothelial cell adhesion molecule-1, a mature neuronal and endothelial marker, respectively, in most forebrain regions. In the RMS, KLF6 was co-expressed with polysialic neural cell adhesion molecule, a marker of neuronal progenitor cells. This is the first report showing that KLF6 protein is expressed in various regions of the adult forebrain and KLF6-positive cells manifest neuronal or endothelial phenotypes under physiological conditions.
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Affiliation(s)
- Kyoung Hoon Jeong
- Department of Pharmacology, Cell Death Disease Research Center, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, 137-701 Seoul, Republic of Korea
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Abstract
Epigenetics refers to chromatin-based pathways important in the regulation of gene expression and includes 3 distinct, but highly interrelated, mechanisms: DNA methylation, histone density and posttranslational modifications, and RNA-based mechanisms. Together, they offer a newer perspective on transcriptional control paradigms in vascular endothelial cells and provide a molecular basis for how the environment impacts the genome to modify disease susceptibility. This review provides an introduction to epigenetic concepts for vascular biologists. Using endothelial nitric oxide synthase (NOS3) as an example, we examine the growing body of evidence implicating epigenetic pathways in the control of vascular endothelial gene expression in health and disease.
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Affiliation(s)
- Charles C Matouk
- Institute of Medical Sciences, St. Michael's Hospital and University of Toronto, Ontario, Canada
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Bentov I, Narla G, Schayek H, Akita K, Plymate SR, LeRoith D, Friedman SL, Werner H. Insulin-like growth factor-i regulates Kruppel-like factor-6 gene expression in a p53-dependent manner. Endocrinology 2008; 149:1890-7. [PMID: 18174288 DOI: 10.1210/en.2007-0844] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
High-circulating IGF-I concentrations are associated with an increased risk for breast, prostate, and colorectal cancer. Krüppel-like factor-6 (KLF6) is a zinc finger tumor suppressor inactivated in prostate and other types of cancer. We have previously demonstrated that KLF6 is a potent transactivator of the IGF-I receptor promoter. The aim of the present study was to examine the potential regulation of KLF6 gene expression by IGF-I. The human colon cancer cell lines HCT116 +/+ and -/- (with normal and disrupted p53, respectively) were treated with IGF-I. Western blots, quantitative RT-PCR, and transfection assays were used to evaluate the effect of IGF-I on KLF-6 production. Signaling pathway inhibitors were used to identify the mechanisms responsible for regulation of KLF6 expression. Small interfering RNA against p53 and KLF6 was used to assess the role of p53 in regulation of KLF6 expression by IGF-I and to evaluate KLF6 involvement in cell cycle control. Results obtained showed that IGF-I stimulated KLF-6 transcription in cells with normal, but not disrupted, p53, suggesting that KLF6 is a downstream target for IGF-I action. Stimulation of KLF6 expression by IGF-I in a p53-dependent manner may constitute a novel mechanism of action of IGF-I, with implications in normal cell cycle progression and cancer biology.
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Affiliation(s)
- Itay Bentov
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Guo H, Lin Y, Zhang H, Liu J, Zhang N, Li Y, Kong D, Tang Q, Ma D. Tissue factor pathway inhibitor-2 was repressed by CpG hypermethylation through inhibition of KLF6 binding in highly invasive breast cancer cells. BMC Mol Biol 2007; 8:110. [PMID: 18053161 PMCID: PMC2233638 DOI: 10.1186/1471-2199-8-110] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 12/03/2007] [Indexed: 12/16/2022] Open
Abstract
Background Tissue factor pathway inhibitor-2 (TFPI-2) is a matrix-associated Kunitz inhibitor that inhibits plasmin and trypsin-mediated activation of zymogen matrix metalloproteinases involved in tumor progression, invasion and metastasis. Here, we have investigated the mechanism of DNA methylation on the repression of TFPI-2 in breast cancer cell lines. Results We found that both protein and mRNA of TFPI-2 could not be detected in highly invasive breast cancer cell line MDA-MB-435. To further investigate the mechanism of TFPI-2 repression in breast cancer cells, 1.5 Kb TFPI-2 promoter was cloned, and several genetic variations were detected, but the promoter luciferase activities were not affected by the point mutation in the promoter region and the phenomena was further supported by deleted mutation. Scan mutation and informatics analysis identified a potential KLF6 binding site in TFPI-2 promoter. It was revealed, by bisulfite modified sequence, that the CpG island in TFPI-2 promoter region was hypermethylated in MDA-MB-435. Finally, using EMSA and ChIP assay, we demonstrated that the CpG methylation in the binding site of KLF-6 diminished the binding of KLF6 to TFPI-2 promoter. Conclusion In this study, we found that the CpG islands in TFPI-2 promoter was hypermethylated in highly invasive breast cancer cell line, and DNA methylation in the entire promoter region caused TFPI-2 repression by inducing inactive chromatin structure and decreasing KLF6 binding to its DNA binding sequence.
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Affiliation(s)
- Hongshen Guo
- Key Laboratory of Molecular Medicine, Ministry of Education, Yixueyuan Road 138#, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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Narla G, Kremer-Tal S, Matsumoto N, Zhao X, Yao S, Kelley K, Tarocchi M, Friedman SL. In vivo regulation of p21 by the Kruppel-like factor 6 tumor-suppressor gene in mouse liver and human hepatocellular carcinoma. Oncogene 2007; 26:4428-34. [PMID: 17297474 DOI: 10.1038/sj.onc.1210223] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Kruppel-like factor (KLF) 6 is a tumor-suppressor gene functionally inactivated by loss of heterozygosity, somatic mutation and/or alternative splicing that generates a dominant-negative splice form, KLF6-SV1. Wild-type KLF6 (wtKLF6) expression is decreased in many human malignancies, which correlates with reduced patient survival. Additionally, loss of the KLF6 locus in the absence of somatic mutation in the remaining allele occurs in a number of human cancers, raising the possibility that haploinsufficiency of the KLF6 gene alone contributes to cellular growth dysregulation and tumorigenesis. Our earlier studies identified the cyclin-dependent kinase inhibitor p21 as a transcriptional target of the KLF6 gene in cultured cells, but not in vivo. To address this issue, we have generated two genetic mouse models to define the in vivo role of KLF6 in regulating cell proliferation and p21 expression. Transgenic overexpression of KLF6 in the liver resulted in a runted phenotype with decreased body and liver size, with evidence of decreased hepatocyte proliferation, increased p21 and reduced proliferating cell nuclear antigen expression. In contrast, mice with targeted deletion of one KLF6 allele (KLF6+/-) display increased liver mass with reduced p21 expression, compared to wild type littermates. Moreover, in primary hepatocellular carcinoma samples, there is a significant correlation between wtKLF6 and p21 mRNA expression. Combined, these data suggest that haploinsufficiency of the KLF6 gene may regulate cellular proliferation in vivo through decreased transcriptional activation of the cyclin-dependent kinase inhibitor p21.
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Affiliation(s)
- G Narla
- Department of Medicine, The Mount Sinai School of Medicine, New York, NY 10029, USA
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Chowdhury B, Krishnan S, Tsokos CG, Robertson JW, Fisher CU, Nambiar MP, Tsokos GC. Stability and translation of TCR zeta mRNA are regulated by the adenosine-uridine-rich elements in splice-deleted 3' untranslated region of zeta-chain. THE JOURNAL OF IMMUNOLOGY 2007; 177:8248-57. [PMID: 17114503 DOI: 10.4049/jimmunol.177.11.8248] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Systemic lupus erythematosus (SLE) T cells display reduced expression of TCR zeta protein. Recently, we reported that in SLE T cells, the residual TCR zeta protein is predominantly derived from an alternatively spliced form that undergoes splice deletion of 562 nt (from 672 to 1233 bases) within the 3' untranslated region (UTR) of TCR zeta mRNA. The stability and translation of the alternatively spliced form of TCR zeta mRNA are low compared with that of the wild-type TCR zeta mRNA. We report that two adenosine-uridine-rich sequence elements (AREs), defined by the splice-deleted 3' UTR region, but not an ARE located upstream are responsible for securing TCR zeta mRNA stability and translation. The stabilizing effect of the splice-deleted region-defined AREs extended to the luciferase mRNA and was not cell type-specific. The findings demonstrate distinct sequences within the splice-deleted region 672 to 1233 of the 3' UTR, which regulate the transcription, mRNA stability, and translation of TCR zeta mRNA. The absence of these sequences represents a molecular mechanism that contributes to altered TCR zeta-chain expression in lupus.
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Affiliation(s)
- Bhabadeb Chowdhury
- Department of Cellular Injury, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
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O'Grady EP, Mulcahy H, O'Callaghan J, Adams C, O'Gara F. Pseudomonas aeruginosa infection of airway epithelial cells modulates expression of Kruppel-like factors 2 and 6 via RsmA-mediated regulation of type III exoenzymes S and Y. Infect Immun 2006; 74:5893-902. [PMID: 16988269 PMCID: PMC1594899 DOI: 10.1128/iai.00489-06] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Pseudomonas aeruginosa is an important opportunistic pathogen which is capable of causing both acute and chronic infections in immunocompromised patients. Successful adaptation of the bacterium to its host environment relies on the ability of the organism to tightly regulate gene expression. RsmA, a small RNA-binding protein, controls the expression of a large number of virulence-related genes in P. aeruginosa, including those encoding the type III secretion system and associated effector proteins, with important consequences for epithelial cell morphology and cytotoxicity. In order to examine the influence of RsmA-regulated functions in the pathogen on gene expression in the host, we compared global expression profiles of airway epithelial cells in response to infection with P. aeruginosa PAO1 and an rsmA mutant. The RsmA-dependent response of host cells was characterized by significant changes in the global transcriptional pattern, including the increased expression of two Kruppel-like factors, KLF2 and KLF6. This increased expression was mediated by specific type III effector proteins. ExoS was required for the enhanced expression of KLF2, whereas both ExoS and ExoY were required for the enhanced expression of KLF6. Neither ExoT nor ExoU influenced the expression of the transcription factors. Additionally, the increased gene expression of KLF2 and KLF6 was associated with ExoS-mediated cytotoxicity. Therefore, this study identifies for the first time the human transcription factors KLF2 and KLF6 as targets of the P. aeruginosa type III exoenzymes S and Y, with potential importance in host cell death.
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Affiliation(s)
- Eoin P O'Grady
- BIOMERIT Research Centre, Department of Microbiology, University College Cork, Cork, Ireland
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Kiang JG, Peckham RM, Duke LE, Shimizu T, Chaudry IH, Tsokos GC. Androstenediol inhibits the trauma-hemorrhage-induced increase in caspase-3 by downregulating the inducible nitric oxide synthase pathway. J Appl Physiol (1985) 2006; 102:933-41. [PMID: 17110508 DOI: 10.1152/japplphysiol.00919.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Soft tissue trauma and hemorrhage (T-H) diminishes various aspects of liver function, while it increases hepatic nitrate/nitrite, inducible nitric oxide synthase (iNOS), and endothelin-1 levels. Treatment with androstenediol (AED) inhibits the T-H-induced alterations of the above parameters. We sought to identify the molecular events underlying the beneficial effect of AED. Exposure of rats to T-H significantly increased the caspase-3 activity and protein, whereas treatment with AED significantly limited these increases. AED treatment also suppressed the T-H-induced increase in iNOS by effectively altering the levels of key transcription factors involved in the regulation of iNOS expression. Immunoprecipitation and immunoblotting analyses indicate that T-H increased apoptosome formation, and AED treatment significantly decreased it. Modulating the iNOS protein by transfecting cells with iNOS gene or small interfering RNA further confirmed the correlation between iNOS and caspase-3. Our data indicate that AED limits caspase-3 expression by suppressing the expression of transcription factors involved in the production of iNOS, resulting in decreased apoptosome. AED can potentially be a useful adjuvant for limiting liver apoptosis following T-H shock.
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Affiliation(s)
- Juliann G Kiang
- Department of Cellular Injury, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
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Lu DY, Liou HC, Tang CH, Fu WM. Hypoxia-induced iNOS expression in microglia is regulated by the PI3-kinase/Akt/mTOR signaling pathway and activation of hypoxia inducible factor-1α. Biochem Pharmacol 2006; 72:992-1000. [PMID: 16919605 DOI: 10.1016/j.bcp.2006.06.038] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 06/25/2006] [Accepted: 06/28/2006] [Indexed: 11/19/2022]
Abstract
Exposure to hypoxia induced microglia activation and animal studies have shown that neuronal cell death is correlated with microglial activation following cerebral ischemia. Thus, it is likely that toxic inflammatory mediators produced by activated microglia under hypoxic conditions may exacerbate neuronal injury following cerebral ischemia. The hypoxia-inducible factor-1 (HIF-1) is primarily involved in the sensing and adapting of cells to changes in the O(2) level, which is regulated by many physiological functions. However, the role of HIF-1 in microglia activation under hypoxia has not yet been defined. In the current work, we investigate the signaling pathways of HIF-1alpha involved in the regulation of hypoxia-induced overexpression of inducible NO synthase (iNOS) in microglia. Exposure of primary rat microglial cultures as well as established microglial cell line BV-2 to hypoxia induced the expression of iNOS, indicating that hypoxia could lead to the inflammatory activation of microglia. iNOS induction was accompanied with NO production. Moreover, the molecular analysis of these events indicated that iNOS expression was regulated by the phosphatidylinositol 3-kinase (PI3-kinase)/AKT/ mammalian target of rapamycin (mTOR) signaling pathway and activation of hypoxia inducible factor-1alpha (HIF-1alpha). Thus, during cerebral ischemia, hypoxia may not only directly damage neurons, but also promote neuronal injury indirectly via microglia activation. In this study, we demonstrated that hypoxia induced iNOS expression by regulation of HIF-1alpha in microglia.
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Affiliation(s)
- Dah-Yuu Lu
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan
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Du Q, Park KS, Guo Z, He P, Nagashima M, Shao L, Sahai R, Geller DA, Hussain SP. Regulation of human nitric oxide synthase 2 expression by Wnt beta-catenin signaling. Cancer Res 2006; 66:7024-31. [PMID: 16849547 DOI: 10.1158/0008-5472.can-05-4110] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitric oxide (NO.), an important mediator of inflammation, and beta-catenin, a component of the Wnt-adenomatous polyposis coli signaling pathway, contribute to the development of cancer. We have identified two T-cell factor 4 (Tcf-4)-binding elements (TBE1 and TBE2) in the promoter of human inducible NO synthase 2 (NOS2). We tested the hypothesis that beta-catenin regulates human NOS2 gene. Mutation in either of the two TBE sites decreased the basal and cytokine-induced NOS2 promoter activity in different cell lines. The promoter activity was significantly reduced when both TBE1 and TBE2 sites were mutated (P < 0.01). Nuclear extract from HCT116, HepG2, or DLD1 cells bound to NOS2 TBE1 or TBE2 oligonucleotides in electrophoretic mobility shift assays and the specific protein-DNA complexes were supershifted with anti-beta-catenin or anti-Tcf-4 antibody. Overexpression of beta-catenin and Tcf-4 significantly increased both basal and cytokine-induced NOS2 promoter activity (P < 0.01), and the induction was dependent on intact TBE sites. Overexpression of beta-catenin or Tcf-4 increased NOS2 mRNA and protein expression in HCT116 cells. Lithium chloride (LiCl), an inhibitor of glycogen synthase kinase-3beta, increased cytosolic and nuclear beta-catenin level, NOS2 expression, and NO. production in primary human and rat hepatocytes and cancer cell lines. Treatment with Wnt-3A-conditioned medium increased beta-catenin and NOS2 expression in fetal human hepatocytes. When administered in vivo, LiCl increased hepatic beta-catenin level in a dose-dependent manner with simultaneous increase in NOS2 expression. These data are consistent with the hypothesis that beta-catenin up-regulates NOS2 and suggest a novel mechanism by which the Wnt/beta-catenin signaling pathway may contribute to cancer by increasing NO. production.
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Affiliation(s)
- Qiang Du
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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Lee SJ, Yang EK, Kim SG. Peroxisome Proliferator-Activated Receptor-γ and Retinoic Acid X Receptor α Represses theTGFβ1Gene via PTEN-Mediated p70 Ribosomal S6 Kinase-1 Inhibition: Role for Zf9 Dephosphorylation. Mol Pharmacol 2006; 70:415-25. [PMID: 16611854 DOI: 10.1124/mol.106.022954] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peroxisome proliferator-activated receptor (PPAR)-gamma and retinoic acid X receptor (RXR) heterodimer regulates cell growth and differentiation. Zinc finger transcription factor-9 (Zf9), whose phosphorylation promotes target genes, is a transcription factor essential for transactivation of the transforming growth factor (TGF)-beta1 gene. This study investigated whether activation of PPARgamma-RXR heterodimer inhibits TGFbeta1 gene transcription and Zf9 phosphorylation and, if so, what signaling pathway regulates it. Either 15-deoxy-delta(12,14)-prostaglandin J2 (PGJ2) or 9-cis-retinoic acid (RA) treatment decreased the TGFbeta1 mRNA level in L929 fibroblasts. PGJ2 + RA, compared with individual treatment alone, synergistically inhibited the TGFbeta1 gene expression, which was abrogated by PPARgamma antagonists. Likewise, PGJ2 + RA decreased luciferase expression from the TGFbeta1 gene promoter. Promoter deletion analysis of the TGFbeta1 gene revealed that pGL3-323 making up to -323-base pair region, but lacking PPAR-responsive elements, responded to PGJ2 + RA. PGJ2 + RA treatment inhibited the activity of p70 ribosomal S6 kinase-1 (S6K1), abolishing Zf9 phosphorylation at serine as did rapamycin [a mammalian target of rapamycin (mTOR) inhibitor]. Zf9 dephosphorylation by PGJ2 + RA was reversed by transfection of cells with the plasmid encoding constitutively active S6K1 (CA-S6K1). Transfection with dominant negative S6K1 inhibited the TGFbeta1 gene. TGFbeta1 gene repression by PGJ2 + RA was consistently antagonized by CA-S6K1. Ectopic expression of PPARgamma1 and RXRalpha repressed pGL3-323 transactivation with S6K1 inhibition, which was abrogated by CA-S6K1 transfection. PGJ2 + RA induced phosphatase and tensin homolog deleted on chromosome 10 (PTEN), whose overexpression repressed the TGFbeta1 gene through S6K1 inhibition, decreasing extracellular signal-regulated kinase 1/2-90-kDa ribosomal S6 kinase 1 and Akt-mTOR phosphorylations. Data indicate that activation of PPARgamma-RXR heterodimer represses the TGFbeta1 gene and induces Zf9 dephosphorylation via PTEN-mediated S6K1 inhibition, providing insight into pharmacological manipulation of the TGFbeta1 gene regulation.
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Affiliation(s)
- Seung Jin Lee
- College of Pharmacy, Seoul National University, Sillim-dong, Kwanak-gu, Seoul 151-742, Korea
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Li D, Yea S, Dolios G, Martignetti JA, Narla G, Wang R, Walsh MJ, Friedman SL. Regulation of Kruppel-like factor 6 tumor suppressor activity by acetylation. Cancer Res 2005; 65:9216-25. [PMID: 16230382 DOI: 10.1158/0008-5472.can-05-1040] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Krüppel-like factor 6 (KLF6) is a zinc finger transcription factor and tumor suppressor that is inactivated in a number of human cancers by mutation, allelic loss, and/or promoter methylation. A key mechanism of growth inhibition by wild-type KLF6 is through p53-independent up-regulation of p21(WAF1/cip1) (CDKN1A), which is abrogated in several tumor-derived mutants. Here we show by chromatin immunoprecipitation that transactivation of p21(WAF1/cip1) by KLF6 occurs through its direct recruitment to the p21(WAF1/cip1) promoter and requires acetylation by histone acetyltransferase activity of either cyclic AMP-responsive element binding protein-binding protein or p300/CBP-associated factor. Direct lysine acetylation of KLF6 peptides can be shown by mass spectrometry. A single lysine-to-arginine point mutation (K209R) derived from prostate cancer reduces acetylation of KLF6 and abrogates its capacity to up-regulate endogenous p21(WAF1/cip1) and reduce cell proliferation. These data indicate that acetylation may regulate KLF6 function, and its loss in some tumor-derived mutants could contribute to its failure to suppress growth in prostate cancer.
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Affiliation(s)
- Dan Li
- Department of Human Genetics, Mount Sinai School of Medicine, New York, NY 10029-6574, USA
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45
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Chan GC, Fish JE, Mawji IA, Leung DD, Rachlis AC, Marsden PA. Epigenetic basis for the transcriptional hyporesponsiveness of the human inducible nitric oxide synthase gene in vascular endothelial cells. THE JOURNAL OF IMMUNOLOGY 2005; 175:3846-61. [PMID: 16148131 DOI: 10.4049/jimmunol.175.6.3846] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A marked difference exists in the inducibility of inducible NO synthase (iNOS) between humans and rodents. Although important cis and trans factors in the murine and human iNOS promoters have been characterized using episomal-based approaches, a compelling molecular explanation for why human iNOS is resistant to induction has not been reported. In this study we present evidence that the hyporesponsiveness of the human iNOS promoter is based in part on epigenetic silencing, specifically hypermethylation of CpG dinucleotides and histone H3 lysine 9 methylation. Using bisulfite sequencing, we demonstrated that the iNOS promoter was heavily methylated at CpG dinucleotides in a variety of primary human endothelial cells and vascular smooth muscle cells, all of which are notoriously resistant to iNOS induction. In contrast, in human cell types capable of iNOS induction (e.g., A549 pulmonary adenocarcinoma, DLD-1 colon adenocarcinoma, and primary hepatocytes), the iNOS promoter was relatively hypomethylated. Treatment of human cells, such as DLD-1, with a DNA methyltransferase inhibitor (5-azacytidine) induced global and iNOS promoter DNA hypomethylation. Importantly, 5-azacytidine enhanced the cytokine inducibility of iNOS. Using chromatin immunoprecipitation, we found that the human iNOS promoter was basally enriched with di- and trimethylation of H3 lysine 9 in endothelial cells, and this did not change with cytokine addition. This contrasted with the absence of lysine 9 methylation in inducible cell types. Importantly, chromatin immunoprecipitation demonstrated the selective presence of the methyl-CpG-binding transcriptional repressor MeCP2 at the iNOS promoter in endothelial cells. Collectively, our work defines a role for chromatin-based mechanisms in the control of human iNOS gene expression.
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MESH Headings
- Cell Line, Tumor
- Cells, Cultured
- Chromatin
- CpG Islands
- DNA Methylation
- Endothelial Cells/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Epigenesis, Genetic
- Gene Silencing
- Histones
- Humans
- Lysine
- Methyl-CpG-Binding Protein 2/analysis
- Methyl-CpG-Binding Protein 2/physiology
- Methylation
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Promoter Regions, Genetic
- Species Specificity
- Transcription, Genetic
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Affiliation(s)
- Gary C Chan
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
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Feinberg MW, Cao Z, Wara AK, Lebedeva MA, Senbanerjee S, Jain MK. Kruppel-like factor 4 is a mediator of proinflammatory signaling in macrophages. J Biol Chem 2005; 280:38247-58. [PMID: 16169848 DOI: 10.1074/jbc.m509378200] [Citation(s) in RCA: 222] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Activation of macrophages is important in chronic inflammatory disease states such as atherosclerosis. Proinflammatory cytokines such as interferon-gamma (IFN-gamma), lipopolysaccharide (LPS), or tumor necrosis factor-alpha can promote macrophage activation. Conversely, anti-inflammatory factors such as transforming growth factor-beta1 (TGF-beta1) can decrease proinflammatory activation. The molecular mediators regulating the balance of these opposing effectors remain incompletely understood. Herein, we identify Kruppel-like factor 4 (KLF4) as being markedly induced in response to IFN-gamma, LPS, or tumor necrosis factor-alpha and decreased by TGF-beta1 in macrophages. Overexpression of KLF4 in J774a macrophages induced the macrophage activation marker inducible nitric-oxide synthase and inhibited the TGF-beta1 and Smad3 target gene plasminogen activator inhibitor-1 (PAI-1). Conversely, KLF4 knockdown markedly attenuated the ability of IFN-gamma, LPS, or IFN-gamma plus LPS to induce the iNOS promoter, whereas it augmented macrophage responsiveness to TGF-beta1 and Smad3 signaling. The KLF4 induction of the iNOS promoter is mediated by two KLF DNA-binding sites at -95 and -212 bp, and mutation of these sites diminished induction by IFN-gamma and LPS. We further provide evidence that KLF4 interacts with the NF-kappaB family member p65 (RelA) to cooperatively induce the iNOS promoter. In contrast, KLF4 inhibited the TGF-beta1/Smad3 induction of the PAI-1 promoter independent of KLF4 DNA binding through a novel antagonistic competition with Smad3 for the C terminus of the coactivator p300/CBP. These findings support an important role for KLF4 as a regulator of key signaling pathways that control macrophage activation.
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Affiliation(s)
- Mark W Feinberg
- Program in Cardiovascular Transcriptional Biology, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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47
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Gehrau RC, D'Astolfo DS, Prieto C, Bocco JL, Koritschoner NP. Genomic organization and functional analysis of the gene encoding the Krüppel-like transcription factor KLF6. ACTA ACUST UNITED AC 2005; 1730:137-46. [PMID: 16054710 DOI: 10.1016/j.bbaexp.2005.06.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 06/08/2005] [Accepted: 06/10/2005] [Indexed: 12/31/2022]
Abstract
The Krüppel-like transcription Factor 6 (KLF6) is regulated during cell proliferation and differentiation events like mammalian development and tissue regeneration, while its aberrant expression is associated with tumor formation. To investigate KLF6 transcriptional control, the genomic organization of human KLF6 together with its cis-regulatory region was analyzed. A high sequence homology of KLF6 regulatory regions was found in mammals, which in turn predicts a high degree of evolutionary conserved transcriptional mechanisms. A transcription start site was identified at the first nucleotide downstream of a potential initiator element. Also, the role of KLF6 regulatory regions was determined by transfection experiments. A minimal promoter region lacking a TATA-box yet containing an Initiator was identified and found to be active in all cells analyzed. In addition, two strong activating sequences were located between positions -407/-344 and -307/-207, where the latter contained Sp1 and CAAT-box sites. Furthermore, ectopic expression of Sp1 increased the transcriptional activity of the KLF6 promoter. In conclusion, our data revealed that KLF6 gene transcription is under control of a TATA-box independent initiation mechanism together with an evolutionary conserved array of positive cis-acting elements.
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Affiliation(s)
- Ricardo C Gehrau
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, 5000-Córdoba, Argentina
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48
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Kleinert H, Pautz A, Linker K, Schwarz PM. Regulation of the expression of inducible nitric oxide synthase. Eur J Pharmacol 2005; 500:255-66. [PMID: 15464038 DOI: 10.1016/j.ejphar.2004.07.030] [Citation(s) in RCA: 447] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2004] [Indexed: 01/24/2023]
Abstract
The role of nitric oxide (NO) generated by the inducible isoform of nitric oxide synthase (iNOS) is very complex. Induction of iNOS expression and hence NO production has been described to have beneficial antiviral, antiparasital, microbicidal, immunomodulatory, and antitumoral effects. However, induced at the wrong place or at the wrong time, iNOS has detrimental consequences and seems to be involved in the pathophysiology of different human diseases. The pathways regulating iNOS expression seem to vary in different cells or different species. In general, activation of the transcription factors nuclear factor (NF)-kappaB and signal transducer and activator of transcription (STAT)-1alpha and thereby activation of the iNOS promoter seems to be an essential step in the regulation of iNOS expression in most cells. Also, post-transcriptional mechanisms are critically involved in the regulation of iNOS expression.
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Affiliation(s)
- Hartmut Kleinert
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany.
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49
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Liu J, Cao S, Kim S, Chung EY, Homma Y, Guan X, Jimenez V, Ma X. Interleukin-12: an update on its immunological activities, signaling and regulation of gene expression. CURRENT IMMUNOLOGY REVIEWS 2005; 1:119-137. [PMID: 21037949 DOI: 10.2174/1573395054065115] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Interleukin-12 (IL-12) is a heterodimeric cytokine composed of the p35 and p40 subunits. It is produced by antigen-presenting cells and plays a critical role in host defense against intracellular microbial infection and control of malignancy via its ability to stimulate both innate and adaptive immune effector cells. The potency of IL-12 renders itself to stringent regulation of the timing, locality and magnitude of its production during an immune response. Subversion of the delicate control and balance frequently leads to immunologic disorders. In this article, we provide an update, since our last review of the subject four years ago, on recent advances in: (1) uncovering of novel activities of IL-12 and related molecules in various immunological settings and models; and (2) dissection of the physiological pathways involved in the modulation of IL-12 production by pathogens and immune regulators. The increased understanding of IL-12 immunobiology and expression will likely benefit the development of therapeutic modalities to correct immune dysfunctions.
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50
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Kiang JG. Inducible heat shock protein 70 kD and inducible nitric oxide synthase in hemorrhage/resuscitation-induced injury. Cell Res 2005; 14:450-9. [PMID: 15625011 DOI: 10.1038/sj.cr.7290247] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Inducible head shock protein 70 kD (HSP-70i) has been shown to protect cells, tissues, and organs from harmful assaults in vivo and in vitro experimental models. Hemorrhagic shock followed by resuscitation is the principal cause of death among trauma patients and soldiers in the battlefield. Although the underlying mechanisms are still not fully understood, it has been shown that nitric oxide (NO) overproduction and inducible nitric oxide synthase (iNOS) overexpression play important roles in producing injury caused by hemorrhagic shock including increases in polymorphonuclear neutrophils (PMN) infiltration to injured tissues and leukotriene B(4) (LTB(4)) generation. Moreover, transcription factors responsible for iNOS expression are also altered by hemorrhage and resuscitation. It has been evident that either up-regulation of HSP-70i or down-regulation of iNOS can limit tissue injury caused by ischemia/reperfusion or hemorrhage/resuscitation. In our laboratory, geldanamycin, a member of ansamycin family, has been shown to induce HSP- 70i overexpression and then subsequently to inhibit iNOS expression, to reduce cellular caspase-3 activity, and to preserve cellular ATP levels. HSP-70i is found to couple to iNOS and its transcription factor. Therefore, the complex formation between HSP-70i and iNOS may be a novel mechanism for protection from hemorrhage/resuscitation-induced injury.
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Affiliation(s)
- Juliann G Kiang
- Department of Cellular Injury, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA.
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