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Sun X, Cao S, Mao C, Sun F, Zhang X, Song Y. Post-translational modifications of p65: state of the art. Front Cell Dev Biol 2024; 12:1417502. [PMID: 39050887 PMCID: PMC11266062 DOI: 10.3389/fcell.2024.1417502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 06/14/2024] [Indexed: 07/27/2024] Open
Abstract
P65, a protein subunit of NF-κB, is a widely distributed transcription factor in eukaryotic cells and exerts diverse regulatory functions. Post-translational modifications such as phosphorylation, acetylation, methylation and ubiquitination modulate p65 transcriptional activity and function, impacting various physiological and pathological processes including inflammation, immune response, cell death, proliferation, differentiation and tumorigenesis. The intricate interplay between these modifications can be antagonistic or synergistic. Understanding p65 post-translational modifications not only elucidates NF-κB pathway regulation but also facilitates the identification of therapeutic targets and diagnostic markers for associated clinical conditions.
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Affiliation(s)
- Xutao Sun
- Department of Typhoid, School of Basic Medical Sciences, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Shuo Cao
- Department of Pharmacology, School of Basic Medical Sciences, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Caiyun Mao
- Department of Pharmacology, School of Basic Medical Sciences, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Fengqi Sun
- Department of Pathology, School of Basic Medical Sciences, Heilongjiang University of Chinese Medicine, Harbin, China
| | - Xuanming Zhang
- Department of Orthopedics, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yunjia Song
- Department of Pharmacology, School of Basic Medical Sciences, Heilongjiang University of Chinese Medicine, Harbin, China
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2
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Tofaute M, Weller B, Graß C, Halder H, Dohai B, Falter-Braun P, Krappmann D. SARS-CoV-2 NSP14 MTase activity is critical for inducing canonical NF-κB activation. Biosci Rep 2024; 44:BSR20231418. [PMID: 38131452 PMCID: PMC10776897 DOI: 10.1042/bsr20231418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/07/2023] [Accepted: 12/21/2023] [Indexed: 12/23/2023] Open
Abstract
Upon SARS-CoV-2 infection, patients with severe forms of COVID-19 often suffer from a dysregulated immune response and hyperinflammation. Aberrant expression of cytokines and chemokines is associated with strong activation of the immunoregulatory transcription factor NF-κB, which can be directly induced by the SARS-CoV-2 protein NSP14. Here, we use NSP14 mutants and generated cells with host factor knockouts (KOs) in the NF-κB signaling pathways to characterize the molecular mechanism of NSP14-induced NF-κB activation. We demonstrate that full-length NSP14 requires methyltransferase (MTase) activity to drive NF-κB induction. NSP14 WT, but not an MTase-defective mutant, is poorly expressed and inherent post-translational instability is mediated by proteasomal degradation. Binding of SARS-CoV-2 NSP10 or addition of the co-factor S-adenosylmethionine (SAM) stabilizes NSP14 and augments its potential to activate NF-κB. Using CRISPR/Cas9-engineered KO cells, we demonstrate that NSP14 stimulation of canonical NF-κB activation relies on NF-κB factor p65/RELA downstream of the NEMO/IKK complex, while c-Rel or non-canonical RelB are not required to induce NF-κB transcriptional activity. However, NSP14 overexpression is unable to induce canonical IκB kinase β (IKKβ)/NF-κB signaling and in co-immunoprecipitation assays we do not detect stable associations between NSP14 and NEMO or p65, suggesting that NSP14 activates NF-κB indirectly through its methyltransferase activity. Taken together, our data provide a framework how NSP14 can augment basal NF-κB activation, which may enhance cytokine expression in SARS-CoV-2 infected cells.
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Affiliation(s)
- Marie J. Tofaute
- Research Unit Signaling and Translation, Group Signaling and Immunity, Molecular Targets and Therapeutics Center, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | - Benjamin Weller
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Carina Graß
- Research Unit Signaling and Translation, Group Signaling and Immunity, Molecular Targets and Therapeutics Center, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
| | - Hridi Halder
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Bushra Dohai
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Pascal Falter-Braun
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
- Microbe-Host Interactions, Faculty of Biology, Ludwig-Maximilians-Universität (LMU) München, Planegg-Martinsried, Germany
| | - Daniel Krappmann
- Research Unit Signaling and Translation, Group Signaling and Immunity, Molecular Targets and Therapeutics Center, Helmholtz Zentrum München – German Research Center for Environmental Health, Neuherberg, Germany
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3
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Choi S, Cho N, Kim KK. The implications of alternative pre-mRNA splicing in cell signal transduction. Exp Mol Med 2023; 55:755-766. [PMID: 37009804 PMCID: PMC10167241 DOI: 10.1038/s12276-023-00981-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 01/05/2023] [Accepted: 01/27/2023] [Indexed: 04/04/2023] Open
Abstract
Cells produce multiple mRNAs through alternative splicing, which ensures proteome diversity. Because most human genes undergo alternative splicing, key components of signal transduction pathways are no exception. Cells regulate various signal transduction pathways, including those associated with cell proliferation, development, differentiation, migration, and apoptosis. Since proteins produced through alternative splicing can exhibit diverse biological functions, splicing regulatory mechanisms affect all signal transduction pathways. Studies have demonstrated that proteins generated by the selective combination of exons encoding important domains can enhance or attenuate signal transduction and can stably and precisely regulate various signal transduction pathways. However, aberrant splicing regulation via genetic mutation or abnormal expression of splicing factors negatively affects signal transduction pathways and is associated with the onset and progression of various diseases, including cancer. In this review, we describe the effects of alternative splicing regulation on major signal transduction pathways and highlight the significance of alternative splicing.
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Affiliation(s)
- Sunkyung Choi
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Namjoon Cho
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Kee K Kim
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea.
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4
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Bressy C, Zemani A, Goyal S, Jishkariani D, Lee CN, Chen YH. Inhibition of c-Rel expression in myeloid and lymphoid cells with distearoyl -phosphatidylserine (DSPS) liposomal nanoparticles encapsulating therapeutic siRNA. PLoS One 2022; 17:e0276905. [PMID: 36520934 PMCID: PMC9754606 DOI: 10.1371/journal.pone.0276905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 10/14/2022] [Indexed: 12/23/2022] Open
Abstract
c-Rel, a member of the nuclear factor kappa B (NF-κB) family, is preferentially expressed by immune cells and is known to regulate inflammation, autoimmune diseases and cancer. However, there is a lack of therapeutic intervention to specifically inhibit c-Rel in immune cells. Recent success with Pfizer and Moderna mRNA lipid-encapsulated vaccines as well as FDA approved medicines based on siRNA prompted us to test a lipid nanoparticle-based strategy to silence c-Rel in immune cells. Specifically, we encapsulated c-Rel-targeting siRNA into distearoyl-phosphatidylserine (DSPS)-containing nanoparticles. DSPS is a saturated phospholipid that serves as the "eat-me" signal for professional phagocytes such as macrophages and neutrophils of the immune system. We demonstrated here that incorporation of DSPS in liposome nanoparticles (LNP) improved their uptake by immune cells. LNP containing high concentrations of DSPS were highly effective to transfect not only macrophages and neutrophils, but also lymphocytes, with limited toxicity to cells. However, LNP containing low concentrations of DSPS were more effective to transfect myeloid cells than lymphoid cells. Importantly, DSPS-LNP loaded with a c-Rel siRNA were highly effective to inhibit c-Rel expression in several professional phagocytes tested, which lasted for several days. Taken together, our results suggest that DSPS-LNP armed with c-Rel siRNA could be exploited to target immune cells to limit the development of inflammatory diseases or cancer caused by c-Rel upregulation. In addition, this newly developed DSPS-LNP system may be further tested to encapsulate and deliver other small molecule drugs to immune cells, especially macrophages, neutrophils, and lymphocytes for the treatment of diseases.
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Affiliation(s)
- Christian Bressy
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (CB); (YHC)
| | - Ali Zemani
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shreya Goyal
- Department of Biological Sciences, University of North Carolina, Charlotte, North Carolina, United States of America
| | - Davit Jishkariani
- Chemical and Nanoparticle Synthesis Core (CNSC), The University of Pennsylvania, Philadelphia, PA, United States of America
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Chin Nien Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Youhai H. Chen
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Faculty of Pharmaceutical Sciences, CAS Shenzhen Institute of Advanced Technology, Shenzhen, China
- * E-mail: (CB); (YHC)
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5
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Dynamic Variations of 3'UTR Length Reprogram the mRNA Regulatory Landscape. Biomedicines 2021; 9:biomedicines9111560. [PMID: 34829789 PMCID: PMC8615635 DOI: 10.3390/biomedicines9111560] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/10/2021] [Accepted: 10/15/2021] [Indexed: 12/16/2022] Open
Abstract
This paper concerns 3′-untranslated regions (3′UTRs) of mRNAs, which are non-coding regulatory platforms that control stability, fate and the correct spatiotemporal translation of mRNAs. Many mRNAs have polymorphic 3′UTR regions. Controlling 3′UTR length and sequence facilitates the regulation of the accessibility of functional effectors (RNA binding proteins, miRNAs or other ncRNAs) to 3′UTR functional boxes and motifs and the establishment of different regulatory landscapes for mRNA function. In this context, shortening of 3′UTRs would loosen miRNA or protein-based mechanisms of mRNA degradation, while 3′UTR lengthening would strengthen accessibility to these effectors. Alterations in the mechanisms regulating 3′UTR length would result in widespread deregulation of gene expression that could eventually lead to diseases likely linked to the loss (or acquisition) of specific miRNA binding sites. Here, we will review the mechanisms that control 3′UTR length dynamics and their alterations in human disorders. We will discuss, from a mechanistic point of view centered on the molecular machineries involved, the generation of 3′UTR variability by the use of alternative polyadenylation and cleavage sites, of mutually exclusive terminal alternative exons (exon skipping) as well as by the process of exonization of Alu cassettes to generate new 3′UTRs with differential functional features.
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6
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Fultang N, Li X, Li T, Chen YH. Myeloid-Derived Suppressor Cell Differentiation in Cancer: Transcriptional Regulators and Enhanceosome-Mediated Mechanisms. Front Immunol 2021; 11:619253. [PMID: 33519825 PMCID: PMC7840597 DOI: 10.3389/fimmu.2020.619253] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 11/30/2020] [Indexed: 01/16/2023] Open
Abstract
Myeloid-derived Suppressor Cells (MDSCs) are a sub-population of leukocytes that are important for carcinogenesis and cancer immunotherapy. During carcinogenesis or severe infections, inflammatory mediators induce MDSCs via aberrant differentiation of myeloid precursors. Although several transcription factors, including C/EBPβ, STAT3, c-Rel, STAT5, and IRF8, have been reported to regulate MDSC differentiation, none of them are specifically expressed in MDSCs. How these lineage-non-specific transcription factors specify MDSC differentiation in a lineage-specific manner is unclear. The recent discovery of the c-Rel-C/EBPβ enhanceosome in MDSCs may help explain these context-dependent roles. In this review, we examine several transcriptional regulators of MDSC differentiation, and discuss the concept of non-modular regulation of MDSC signature gene expression by transcription factors such as c-Rel and C/EBPß.
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Affiliation(s)
- Norman Fultang
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | | | | | - Youhai H. Chen
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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7
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Liaño-Pons J, Lafita-Navarro MC, García-Gaipo L, Colomer C, Rodríguez J, von Kriegsheim A, Hurlin PJ, Ourique F, Delgado MD, Bigas A, Espinosa L, León J. A novel role of MNT as a negative regulator of REL and the NF-κB pathway. Oncogenesis 2021; 10:5. [PMID: 33419981 PMCID: PMC7794610 DOI: 10.1038/s41389-020-00298-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 11/20/2020] [Accepted: 12/02/2020] [Indexed: 01/29/2023] Open
Abstract
MNT, a transcription factor of the MXD family, is an important modulator of the oncoprotein MYC. Both MNT and MYC are basic-helix-loop-helix proteins that heterodimerize with MAX in a mutually exclusive manner, and bind to E-boxes within regulatory regions of their target genes. While MYC generally activates transcription, MNT represses it. However, the molecular interactions involving MNT as a transcriptional regulator beyond the binding to MAX remain unexplored. Here we demonstrate a novel MAX-independent protein interaction between MNT and REL, the oncogenic member of the NF-κB family. REL participates in important biological processes and it is altered in a variety of tumors. REL is a transcription factor that remains inactive in the cytoplasm in an inhibitory complex with IκB and translocates to the nucleus when the NF-κB pathway is activated. In the present manuscript, we show that MNT knockdown triggers REL translocation into the nucleus and thus the activation of the NF-κB pathway. Meanwhile, MNT overexpression results in the repression of IκBα, a bona fide REL target. Both MNT and REL bind to the IκBα gene on the first exon, suggesting its regulation as an MNT-REL complex. Altogether our data indicate that MNT acts as a repressor of the NF-κB pathway by two mechanisms: (1) retention of REL in the cytoplasm by MNT interaction, and (2) MNT-driven repression of REL-target genes through an MNT-REL complex. These results widen our knowledge about MNT biological roles and reveal a novel connection between the MYC/MXD and NF-κB pathways, two of the most prominent pathways in cancer.
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Affiliation(s)
- Judit Liaño-Pons
- Departmento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria, Santander, Spain
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum B7, Karolinska Institutet, Stockholm, Sweden
| | - M Carmen Lafita-Navarro
- Departmento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria, Santander, Spain
- Department of Cell Biology UT Southwestern Medical Center, Dallas, TX, USA
| | - Lorena García-Gaipo
- Departmento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria, Santander, Spain
| | - Carlota Colomer
- Cancer Research Program, Institut Hospital del Mar d'Investigacions Mèdiques, CIBERONC, Hospital del Mar, Barcelona, Spain
| | - Javier Rodríguez
- Systems Biology Ireland, University College Dublin, Dublin, Ireland
| | - Alex von Kriegsheim
- Systems Biology Ireland, University College Dublin, Dublin, Ireland
- Edinburgh Cancer Research Center, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Peter J Hurlin
- Shriners Hospitals for Children Research Center, Department of Cell, Developmental and Cancer Biology and Department of Orthopaedics and Rehabilitation, Oregon Health and Science University, Portland, OR, USA
| | - Fabiana Ourique
- Departmento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria, Santander, Spain
- Dept. of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
| | - M Dolores Delgado
- Departmento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria, Santander, Spain
| | - Anna Bigas
- Cancer Research Program, Institut Hospital del Mar d'Investigacions Mèdiques, CIBERONC, Hospital del Mar, Barcelona, Spain
| | - Lluis Espinosa
- Cancer Research Program, Institut Hospital del Mar d'Investigacions Mèdiques, CIBERONC, Hospital del Mar, Barcelona, Spain
| | - Javier León
- Departmento de Biología Molecular, Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), CSIC-Universidad de Cantabria, Santander, Spain.
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8
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Regulation of B-cell function by NF-kappaB c-Rel in health and disease. Cell Mol Life Sci 2020; 77:3325-3340. [PMID: 32130429 DOI: 10.1007/s00018-020-03488-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/03/2020] [Accepted: 02/17/2020] [Indexed: 02/06/2023]
Abstract
B cells mediate humoral immune response and contribute to the regulation of cellular immune response. Members of the Nuclear Factor kappaB (NF-κB) family of transcription factors play a major role in regulating B-cell functions. NF-κB subunit c-Rel is predominantly expressed in lymphocytes, and in B cells, it is required for survival, proliferation, and antibody production. Dysregulation of c-Rel expression and activation alters B-cell homeostasis and is associated with B-cell lymphomas and autoimmune pathologies. Based on its essential roles, c-Rel may serve as a potential prognostic and therapeutic target. This review summarizes the current understanding of the multifaceted role of c-Rel in B cells and B-cell diseases.
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9
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The Unsolved Puzzle of c-Rel in B Cell Lymphoma. Cancers (Basel) 2019; 11:cancers11070941. [PMID: 31277480 PMCID: PMC6678315 DOI: 10.3390/cancers11070941] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/28/2019] [Accepted: 06/29/2019] [Indexed: 01/04/2023] Open
Abstract
Aberrant constitutive activation of Rel/NF-κB transcription factors is a hallmark of numerous cancers. Of the five Rel family members, c-Rel has the strongest direct links to tumorigenesis. c-Rel is the only member that can malignantly transform lymphoid cells in vitro. Furthermore, c-Rel is implicated in human B cell lymphoma through the frequent occurrence of REL gene locus gains and amplifications. In normal physiology, high c-Rel expression predominates in the hematopoietic lineage and a diverse range of stimuli can trigger enhanced expression and activation of c-Rel. Both expression and activation of c-Rel are tightly regulated on multiple levels, indicating the necessity to keep its functions under control. In this review we meta-analyze and integrate studies reporting gene locus aberrations to provide an overview on the frequency of REL gains in human B cell lymphoma subtypes, namely follicular lymphoma, diffuse large B cell lymphoma, primary mediastinal B cell lymphoma, and classical Hodgkin lymphoma. We also summarize current knowledge on c-Rel expression and protein localization in these human B cell lymphomas and discuss the co-amplification of BCL11A with REL. In addition, we highlight and illustrate key pathways of c-Rel activation and regulation with a specific focus on B cell biology.
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10
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Subramanian L, Khan AA, Allu PKR, Kiranmayi M, Sahu BS, Sharma S, Khullar M, Mullasari AS, Mahapatra NR. A haplotype variant of the human chromogranin A gene ( CHGA) promoter increases CHGA expression and the risk for cardiometabolic disorders. J Biol Chem 2017; 292:13970-13985. [PMID: 28667172 PMCID: PMC5572921 DOI: 10.1074/jbc.m117.778134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 06/27/2017] [Indexed: 12/13/2022] Open
Abstract
The acidic glycoprotein chromogranin A (CHGA) is co-stored/co-secreted with catecholamines and crucial for secretory vesicle biogenesis in neuronal/neuroendocrine cells. CHGA is dysregulated in several cardiovascular diseases, but the underlying mechanisms are not well established. Here, we sought to identify common polymorphisms in the CHGA promoter and to explore the mechanistic basis of their plausible contribution to regulating CHGA protein levels in circulation. Resequencing of the CHGA promoter in an Indian population (n = 769) yielded nine single-nucleotide polymorphisms (SNPs): G-1106A, A-1018T, T-1014C, T-988G, G-513A, G-462A, T-415C, C-89A, and C-57T. Linkage disequilibrium (LD) analysis indicated strong LD among SNPs at the -1014, -988, -462, and -89 bp positions and between the -1018 and -57 bp positions. Haplotype analysis predicted five major promoter haplotypes that displayed differential promoter activities in neuronal cells; specifically, haplotype 2 (containing variant T alleles at -1018 and -57 bp) exhibited the highest promoter activity. Systematic computational and experimental analyses revealed that transcription factor c-Rel has a role in activating the CHGA promoter haplotype 2 under basal and pathophysiological conditions (viz. inflammation and hypoxia). Consistent with the higher in vitro CHGA promoter activity of haplotype 2, individuals carrying this haplotype had higher plasma CHGA levels, plasma glucose levels, diastolic blood pressure, and body mass index. In conclusion, these results suggest a functional role of the CHGA promoter haplotype 2 (occurring in a large proportion of the world population) in enhancing CHGA expression in haplotype 2 carriers who may be at higher risk for cardiovascular/metabolic disorders.
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Affiliation(s)
- Lakshmi Subramanian
- From the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036
| | - Abrar A Khan
- From the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036
| | - Prasanna K R Allu
- From the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036
| | - Malapaka Kiranmayi
- From the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036
| | - Bhavani S Sahu
- From the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036
| | - Saurabh Sharma
- Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Madhu Khullar
- Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Ajit S Mullasari
- Institute of Cardiovascular Diseases, Madras Medical Mission, Chennai 600037
| | - Nitish R Mahapatra
- From the Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036.
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11
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Gupta V, Kapopara PR, Khan AA, Arige V, Subramanian L, Sonawane PJ, Sasi BK, Mahapatra NR. Functional promoter polymorphisms direct the expression of cystathionine gamma-lyase gene in mouse models of essential hypertension. J Mol Cell Cardiol 2016; 102:61-73. [PMID: 27865915 DOI: 10.1016/j.yjmcc.2016.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 10/21/2016] [Accepted: 11/11/2016] [Indexed: 11/28/2022]
Abstract
Despite the well-known role of cystathionine γ-lyase (Cth) in cardiovascular pathophysiology, transcriptional regulation of Cth remains incompletely understood. Sequencing of the Cth promoter region in mouse models of genetic/essential hypertension (viz. Blood Pressure High [BPH], Blood Pressure Low [BPL] and Blood Pressure Normal [BPN] mice) identified several genetic variations. Transient transfections of BPH/BPL-Cth promoter-reporter plasmids into various cell types revealed higher promoter activity of BPL-Cth than that of BPH-Cth. Corroboratively, endogenous Cth mRNA levels in kidney and liver tissues were also elevated in BPL mice. Computational analysis of the polymorphic Cth promoter region predicted differential binding affinity of c-Rel, HOXA3 and IRF1 with BPL/BPH-Cth promoter domains. Over-expression of c-Rel/HOXA3/IRF1 modulated BPL/BPH-Cth promoter activities in a consistent manner. Gel shift assays using BPH/BPL-Cth-promoter oligonucleotides with/without binding sites for c-Rel/HOXA3/IRF1 displayed formation of specific complexes with c-Rel/HOXA3/IRF1; addition of antibodies to reaction mixtures resulted in supershifts/inhibition of Cth promoter-transcription factor complexes. Furthermore, chromatin immunoprecipitation (ChIP) assays proved differential binding of c-Rel, HOXA3 and IRF1 with the polymorphic promoter region of BPL/BPH-Cth. Tumor necrosis factor-α (TNF-α) reduced the activities of BPL/BPH-Cth promoters to different extents that were further declined by ectopic expression of IRF1; on the other hand, siRNA-mediated down-regulation of IRF1 rescued the TNF-α-mediated suppression of the BPL/BPH-Cth promoter activities. In corroboration, ChIP analysis revealed enhanced binding of IRF1 with BPH/BPL-Cth promoter following TNF-α treatment. BPL/BPH-Cth promoter activity was diminished upon exposure of hepatocytes and cardiomyoblasts to ischemia-like pathological condition due to reduced binding of c-Rel with BPL/BPH-Cth-promoter. Taken together, this study reveals the molecular basis for the differential expression of Cth in mouse models of essential hypertension under basal and pathophysiological conditions.
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Affiliation(s)
- Vinayak Gupta
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Piyushkumar R Kapopara
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Abrar A Khan
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Vikas Arige
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Lakshmi Subramanian
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Parshuram J Sonawane
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Binu K Sasi
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Nitish R Mahapatra
- Cardiovascular Genetics Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
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Krappmann D, Vincendeau M. Mechanisms of NF-κB deregulation in lymphoid malignancies. Semin Cancer Biol 2016; 39:3-14. [DOI: 10.1016/j.semcancer.2016.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 12/17/2022]
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13
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Hunter JE, Leslie J, Perkins ND. c-Rel and its many roles in cancer: an old story with new twists. Br J Cancer 2016; 114:1-6. [PMID: 26757421 PMCID: PMC4716536 DOI: 10.1038/bjc.2015.410] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/22/2015] [Accepted: 10/05/2015] [Indexed: 01/19/2023] Open
Abstract
When the genes encoding NF-κB subunits were first isolated, their homology to the previously identified c-Rel proto-oncogene and its viral homologue v-Rel was clear. This provided the first indication that these transcription factors also had a role in cancer. Because of its homology to v-Rel, which transforms chicken B cells together with the important role c-Rel can have as a regulator of B- and T-cell proliferation, most attention has focussed on its role in B-cell lymphomas, where the REL gene is frequently amplified. However, a growing number of reports now indicate that c-Rel has important functions in many solid tumours, although studies in mice suggest it may not always function as an oncogene. Moreover, c-Rel is a critical regulator of fibrosis, which provides an environment for tumour development in many settings. Overall, c-Rel is emerging as a complex regulator of tumorigenesis, and there is still much to learn about its functions in human malignancies and the response to cancer therapies.
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Affiliation(s)
- Jill E Hunter
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK
| | - Jack Leslie
- Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK
| | - Neil D Perkins
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK
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14
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Thompson RC, Vardinogiannis I, Gilmore TD. Identification of an NF-κB p50/p65-responsive site in the human MIR155HG promoter. BMC Mol Biol 2013; 14:24. [PMID: 24059932 PMCID: PMC3849010 DOI: 10.1186/1471-2199-14-24] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 09/16/2013] [Indexed: 12/15/2022] Open
Abstract
Background MicroRNA-155 (miR-155) is the diced product of the MIR155HG gene. miR-155 regulates the expression of many immune-specific transcripts, is overexpressed in many human lymphomas, and has oncogenic activity in mouse transgenic models. MIR155HG has been proposed to be a target gene for transcription factor NF-κB largely due to the positive correlation between high nuclear NF-κB activity and increased miR-155 expression following treatment with NF-κB inducers or in subsets of hematopoietic cancers. Nevertheless, direct regulation of the human MIR155HG promoter by NF-κB has not been convincingly demonstrated previously. Results This report shows that induction of NF-κB activity rapidly leads to increased levels of both primary MIR155HG mRNA and mature miR-155 transcripts. We have mapped an NF-κB-responsive element to a position approximately 178 nt upstream of the MIR155HG transcription start site. The -178 site is specifically bound by the NF-κB p50/p65 heterodimer and is required for p65-induced reporter gene activation. Moreover, the levels of miR-155 in nine human B-lymphoma cell lines generally correlate with increased nuclear NF-κB proteins. Conclusion Overall, the identification of an NF-κB-responsive site in the MIR155HG proximal promoter suggests that MIR155HG is a direct NF-κB target gene in vivo. Understanding NF-κB-mediated regulation of miR-155 could lead to improved immune cell-related diagnostic tools and targeted therapies.
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Affiliation(s)
- Ryan C Thompson
- Department of Biology, Boston University, Boston, MA 02215, USA.
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15
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 512] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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16
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Gilmore TD, Gerondakis S. The c-Rel Transcription Factor in Development and Disease. Genes Cancer 2012; 2:695-711. [PMID: 22207895 DOI: 10.1177/1947601911421925] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 08/08/2011] [Indexed: 12/21/2022] Open
Abstract
c-Rel is a member of the nuclear factor κB (NF-κB) transcription factor family. Unlike other NF-κB proteins that are expressed in a variety of cell types, high levels of c-Rel expression are found primarily in B and T cells, with many c-Rel target genes involved in lymphoid cell growth and survival. In addition to c-Rel playing a major role in mammalian B and T cell function, the human c-rel gene (REL) is a susceptibility locus for certain autoimmune diseases such as arthritis, psoriasis, and celiac disease. The REL locus is also frequently altered (amplified, mutated, rearranged), and expression of REL is increased in a variety of B and T cell malignancies and, to a lesser extent, in other cancer types. Thus, agents that modulate REL activity may have therapeutic benefits for certain human cancers and chronic inflammatory diseases.
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17
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Identification of OASL d, a splice variant of human OASL, with antiviral activity. Int J Biochem Cell Biol 2012; 44:1133-8. [PMID: 22531715 DOI: 10.1016/j.biocel.2012.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 03/16/2012] [Accepted: 04/04/2012] [Indexed: 11/21/2022]
Abstract
The 2',5'-oligoadenylate synthetases (OASs) are IFN-induced antiviral proteins and are upregulated by infection of viral and some bacterial pathogens. There are at least 2 transcripts of approximately 1.8 and 2.0 kb in interferon-beta treated samples that are recognized by a probe for human OASL in Northern blot assay. By RT-PCR amplification we have isolated a previously undescribed splice variant of human OASL, named OASL d. The new variant was derived from deletion of exons 4 and 5 and encodes a protein of 384 aa residues that shares the N-terminal 219 aa residues with OASL a. Sequence analysis indicates that OASL d also contains the entire ubiquitin-like domain identified in human OASL a. OASL d was strongly induced by IFNγ in THP-1 monocytic cells and in A549 epithelial cells by interferon-beta as detected by immunoblotting assay. Ectopic expression of OASL a or OASL d, but not OASL b that shares the N-terminus with OASL a and d, partially inhibited EV71 and VSV infection. No effect against HSV-2 infection was observed. Therefore, OASL d is a novel isoform of human OASL that possesses antiviral activity against RNA viruses.
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18
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Fullard N, Wilson CL, Oakley F. Roles of c-Rel signalling in inflammation and disease. Int J Biochem Cell Biol 2012; 44:851-60. [PMID: 22405852 DOI: 10.1016/j.biocel.2012.02.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/22/2012] [Accepted: 02/24/2012] [Indexed: 12/13/2022]
Abstract
Nuclear factor kappa B (NFκB) is a dimeric transcription factor comprised of five family members RelA (p65), RelB, c-Rel, p50 and p52. NFκB signalling is complex and controls a myriad of normal cellular functions. However, constitutive or aberrant activation of this pathway is associated with disease progression and cancer in multiple organs. The diverse array of biological responses is modulated by many factors, including the activating stimulus, recruitment of co-regulatory molecules, consensus DNA binding sequence, dimer composition and post-translational modifications. Each subunit has very different biological functions and in the context of disease the individual subunits forming the NFκB dimer can have a profound effect, causing a shift in the balance from normal to pathogenic signalling. Here we discuss the role of c-Rel dependant signalling in normal physiology and its contribution to disease both inside and outside of the immune system.
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Affiliation(s)
- Nicola Fullard
- Fibrosis Laboratory, Liver Group, Institute of Cellular Medicine, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK
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19
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Characterization of the core elements of the NF-κB signaling pathway of the sea anemone Nematostella vectensis. Mol Cell Biol 2010; 31:1076-87. [PMID: 21189285 DOI: 10.1128/mcb.00927-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The sea anemone Nematostella vectensis is the leading developmental and genomic model for the phylum Cnidaria, which includes anemones, hydras, jellyfish, and corals. In insects and vertebrates, the NF-κB pathway is required for cellular and organismal responses to various stresses, including pathogens and chemicals, as well as for several developmental processes. Herein, we have characterized proteins that comprise the core NF-κB pathway in Nematostella, including homologs of NF-κB, IκB, Bcl-3, and IκB kinase (IKK). We show that N. vectensis NF-κB (Nv-NF-κB) can bind to κB sites and activate transcription of reporter genes containing multimeric κB sites or the Nv-IκB promoter. Both Nv-IκB and Nv-Bcl-3 interact with Nv-NF-κB and block its ability to activate reporter gene expression. Nv-IKK is most similar to human IKKε/TBK kinases and, in vitro, can phosphorylate Ser47 of Nv-IκB. Nv-NF-κB is expressed in a subset of ectodermal cells in juvenile and adult Nematostella anemones. A bioinformatic analysis suggests that homologs of many mammalian NF-κB target genes are targets for Nv-NF-κB, including genes involved in apoptosis and responses to organic compounds and endogenous stimuli. These results indicate that NF-κB pathway proteins in Nematostella are similar to their vertebrate homologs, and these results also provide a framework for understanding the evolutionary origins of NF-κB signaling.
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20
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Thompson RC, Herscovitch M, Zhao I, Ford TJ, Gilmore TD. NF-kappaB down-regulates expression of the B-lymphoma marker CD10 through a miR-155/PU.1 pathway. J Biol Chem 2010; 286:1675-82. [PMID: 20947507 DOI: 10.1074/jbc.m110.177063] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cell-surface protein CD10 is a prognostic marker for diffuse large B-cell lymphoma (DLBCL), where high expression of CD10 is found in the germinal center B-cell (GCB) subtype and CD10 expression is low or absent in the activated B-cell (ABC) subtype. As compared with the GCB subtype, patients with ABC DLBCL have a poorer prognosis after standard treatment, and ABC tumor cells have higher NF-κB activity. Herein, we show that increased expression of the NF-κB target micro-RNA miR-155 is correlated with reduced expression of transcription factor PU.1 and CD10 in several B-lymphoma cell lines. Moreover, electromobility shift assays and luciferase reporter assays indicate that PU.1 can directly activate expression from the CD10 promoter. Expression of a DLBCL-derived mutant of the adaptor CARD11 (a constitutive activator of NF-κB) in the GCB-like human BJAB cell line or v-Rel in the chicken DT40 B-lymphoma cell line causes reduced expression of PU.1. The CARD11 mutant also causes a decrease in CD10 levels in BJAB cells. Similarly, overexpression of miR-155, which is known to down-regulate PU.1, leads to reduced expression of CD10 in BJAB cells. Finally, we show that CD10 expression is reduced in BJAB cells after treatment with the NF-κB inducer lipopolysaccharide (LPS). Additionally, miR-155 is induced by LPS treatment or expression of the CARD11 mutant in BJAB cells. These results point to an NF-κB-dependent mechanism for down-regulation of CD10 in B-cell lymphoma: namely, that increased NF-κB activity leads to increased miR-155, which results in decreased PU.1, and consequently reduced CD10 mRNA and protein.
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Affiliation(s)
- Ryan C Thompson
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA
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21
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Sullivan JC, Wolenski FS, Reitzel AM, French CE, Traylor-Knowles N, Gilmore TD, Finnerty JR. Two alleles of NF-kappaB in the sea anemone Nematostella vectensis are widely dispersed in nature and encode proteins with distinct activities. PLoS One 2009; 4:e7311. [PMID: 19806194 PMCID: PMC2751831 DOI: 10.1371/journal.pone.0007311] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 08/06/2009] [Indexed: 12/22/2022] Open
Abstract
Background NF-κB is an evolutionarily conserved transcription factor that controls the expression of genes involved in many key organismal processes, including innate immunity, development, and stress responses. NF-κB proteins contain a highly conserved DNA-binding/dimerization domain called the Rel homology domain. Methods/Principal Findings We characterized two NF-κB alleles in the sea anemone Nematostella vectensis that differ at nineteen single-nucleotide polymorphisms (SNPs). Ten of these SNPs result in amino acid substitutions, including six within the Rel homology domain. Both alleles are found in natural populations of Nematostella. The relative abundance of the two NF-κB alleles differs between populations, and departures from Hardy-Weinberg equilibrium within populations indicate that the locus may be under selection. The proteins encoded by the two Nv-NF-κB alleles have different molecular properties, in part due to a Cys/Ser polymorphism at residue 67, which resides within the DNA recognition loop. In nearly all previously characterized NF-κB proteins, the analogous residue is fixed for Cys, and conversion of human RHD proteins from Cys to Ser at this site has been shown to increase DNA-binding ability and increase resistance to inhibition by thiol-reactive compounds. However, the naturally-occurring Nematostella variant with Cys at position 67 binds DNA with a higher affinity than the Ser variant. On the other hand, the Ser variant activates transcription in reporter gene assays more effectively, and it is more resistant to inhibition by a thiol-reactive compound. Reciprocal Cys<->Ser mutations at residue 67 of the native Nv-NF-κB proteins affect DNA binding as in human NF-κB proteins, e.g., a Cys->Ser mutation increases DNA binding of the native Cys variant. Conclusions/Significance These results are the first demonstration of a naturally occurring and functionally significant polymorphism in NF-κB in any species. The functional differences between these alleles and their uneven distribution in the wild suggest that different genotypes could be favored in different environments, perhaps environments that vary in their levels of peroxides or thiol-reactive compounds.
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Affiliation(s)
- James C. Sullivan
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Francis S. Wolenski
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Adam M. Reitzel
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Courtney E. French
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Nikki Traylor-Knowles
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Thomas D. Gilmore
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - John R. Finnerty
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
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22
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Overexpression of an activated REL mutant enhances the transformed state of the human B-lymphoma BJAB cell line and alters its gene expression profile. Oncogene 2009; 28:2100-11. [PMID: 19377508 PMCID: PMC2796798 DOI: 10.1038/onc.2009.74] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The human REL proto-oncogene encodes a transcription factor in the NF-κB family. Overexpression of REL is acutely transforming in chicken lymphoid cells, but has not been shown to transform any mammalian lymphoid cell type. In this report, we show that overexpression of a highly transforming mutant of REL (RELΔTAD1) increases the oncogenic properties of the human B-cell lymphoma BJAB cell line, as demonstrated by increased colony formation in soft agar, tumor formation in SCID mice, and adhesion. BJAB-RELΔTAD1 cells also show decreased activation of caspase in response to doxorubicin. BJAB-RELΔTAD1 cells have increased levels of active nuclear REL protein as determined by immunofluorescence, subcellular fractionation, and electrophoretic mobility shift assay. Overexpression of RELΔTAD1 in BJAB cells has transformed the gene expression profile of BJAB cells from that of a germinal center B-cell subtype of diffuse large B-cell lymphoma (GCB-DLBCL) to that of an activated B-cell subtype (ABC-DLBCL), as evidenced by increased expression of many ABC-defining mRNAs. Up-regulated genes in BJAB-RELΔTAD1 cells include several NF-κB targets that encode proteins previously implicated in B-cell development or oncogenesis, including BCL2, IRF4, CD40 and VCAM1. The cell system we describe here may be valuable for further characterizing the molecular details of REL-induced lymphoma in humans.
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23
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Leeman JR, Gilmore TD. Alternative splicing in the NF-kappaB signaling pathway. Gene 2008; 423:97-107. [PMID: 18718859 DOI: 10.1016/j.gene.2008.07.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 07/08/2008] [Accepted: 07/09/2008] [Indexed: 10/21/2022]
Abstract
Activation of transcription factor NF-kappaB can affect the expression of several hundred genes, many of which are involved in inflammation and immunity. The proper NF-kappaB transcriptional response is primarily regulated by post-translational modification of NF-kappaB signaling constituents. Herein, we review the accumulating evidence suggesting that alternative splicing of NF-kappaB signaling components is another means of controlling NF-kappaB signaling. Several alternative splicing events in both the tumor necrosis factor and Toll/interleukin-1 NF-kappaB signaling pathways can inhibit the NF-kappaB response, whereas others enhance NF-kappaB signaling. Alternative splicing of mRNAs encoding some NF-kappaB signaling components can be induced by prolonged exposure to an NF-kappaB-activating signal, such as lipopolysaccharide, suggesting a mechanism for negative feedback to dampen excessive NF-kappaB signaling. Moreover, some NF-kappaB alternative splicing events appear to be specific for certain diseases, and could serve as therapeutic targets or biomarkers.
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Affiliation(s)
- Joshua R Leeman
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
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24
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Garbati MR, Gilmore TD. Ser484 and Ser494 in REL are the major sites of IKK phosphorylation in vitro: evidence that IKK does not directly enhance GAL4-REL transactivation. Gene Expr 2008; 14:195-205. [PMID: 19110719 PMCID: PMC2822992 DOI: 10.3727/105221608786883807] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human c-Rel (REL) is a member of the NF-kappa B family of transcription factors, and one of its primary physiological roles is in the regulation of B-cell proliferation and survival. Although REL is primarily regulated by cytoplasmic-nuclear translocation through interaction with I kappa B inhibitors, REL also undergoes several posttranslational modifications that have been proposed to modulate its transcriptional activation activity. For example, phosphorylation of C-terminal sequences of REL has been proposed to increase its transactivation activity. In this report, we have used immune complex kinase assays to identify Ser484 and Ser494 as the primary sites of IKK alpha- and IKK beta-mediated in vitro phosphorylation in the C-terminal transactivation domain of REL. However, in cotransfection studies in A293 cells we have failed to detect IKK beta-mediated phosphorylation of these sites on REL in vivo, nor does IKK beta appear to interact with REL in these cells. Ser-to-Ala mutation of Ser484 and Ser494 does not affect IKK's ability to enhance GAL4-REL transactivation in reporter gene assays in A293 cells. We also show that the previously reported effects of overexpressed IKK and tumor necrosis factor treatment on GAL4-REL transactivation are due to IKK-mediated activation of the endogenous NF-kappa B pathway, which increases transcription from kappa B sites in the promoter of a commonly used GAL4 expression vector. Taken together, these results do not support a role for IKK-mediated phosphorylation as means for regulating the activity of REL in vivo.
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