1
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Li S, Counter CM. Signaling levels mold the RAS mutation tropism of urethane. eLife 2021; 10:67172. [PMID: 33998997 PMCID: PMC8128437 DOI: 10.7554/elife.67172] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/01/2021] [Indexed: 12/29/2022] Open
Abstract
RAS genes are commonly mutated in human cancer. Despite many possible mutations, individual cancer types often have a 'tropism' towards a specific subset of RAS mutations. As driver mutations, these patterns ostensibly originate from normal cells. High oncogenic RAS activity causes oncogenic stress and different oncogenic mutations can impart different levels of activity, suggesting a relationship between oncoprotein activity and RAS mutation tropism. Here, we show that changing rare codons to common in the murine Kras gene to increase protein expression shifts tumors induced by the carcinogen urethane from arising from canonical Q61 to biochemically less active G12 Kras driver mutations, despite the carcinogen still being biased towards generating Q61 mutations. Conversely, inactivating the tumor suppressor p53 to blunt oncogenic stress partially reversed this effect, restoring Q61 mutations. One interpretation of these findings is that the RAS mutation tropism of urethane arises from selection in normal cells for specific mutations that impart a narrow window of signaling that promotes proliferation without causing oncogenic stress.
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Affiliation(s)
- Siqi Li
- Pharmacology and Cancer Biology, Duke University, Durham, United States
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2
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Jia J, Conlon TM, Sarker RS, Taşdemir D, Smirnova NF, Srivastava B, Verleden SE, Güneş G, Wu X, Prehn C, Gao J, Heinzelmann K, Lintelmann J, Irmler M, Pfeiffer S, Schloter M, Zimmermann R, Hrabé de Angelis M, Beckers J, Adamski J, Bayram H, Eickelberg O, Yildirim AÖ. Cholesterol metabolism promotes B-cell positioning during immune pathogenesis of chronic obstructive pulmonary disease. EMBO Mol Med 2018; 10:e8349. [PMID: 29674392 PMCID: PMC5938615 DOI: 10.15252/emmm.201708349] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 03/08/2018] [Accepted: 03/14/2018] [Indexed: 12/30/2022] Open
Abstract
The development of chronic obstructive pulmonary disease (COPD) pathogenesis remains unclear, but emerging evidence supports a crucial role for inducible bronchus-associated lymphoid tissue (iBALT) in disease progression. Mechanisms underlying iBALT generation, particularly during chronic CS exposure, remain to be defined. Oxysterol metabolism of cholesterol is crucial to immune cell localization in secondary lymphoid tissue. Here, we demonstrate that oxysterols also critically regulate iBALT generation and the immune pathogenesis of COPD In both COPD patients and cigarette smoke (CS)-exposed mice, we identified significantly upregulated CH25H and CYP7B1 expression in airway epithelial cells, regulating CS-induced B-cell migration and iBALT formation. Mice deficient in CH25H or the oxysterol receptor EBI2 exhibited decreased iBALT and subsequent CS-induced emphysema. Further, inhibition of the oxysterol pathway using clotrimazole resolved iBALT formation and attenuated CS-induced emphysema in vivo therapeutically. Collectively, our studies are the first to mechanistically interrogate oxysterol-dependent iBALT formation in the pathogenesis of COPD, and identify a novel therapeutic target for the treatment of COPD and potentially other diseases driven by the generation of tertiary lymphoid organs.
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Affiliation(s)
- Jie Jia
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Thomas M Conlon
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Rim Sj Sarker
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Demet Taşdemir
- Department of Chest Diseases, School of Medicine, University of Gaziantep, Gaziantep, Turkey
| | - Natalia F Smirnova
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Barkha Srivastava
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | | | - Gizem Güneş
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Xiao Wu
- Joint Mass Spectrometry Centre, Comprehensive Molecular Analytics, Helmholtz Zentrum München, Munich, Germany
| | - Cornelia Prehn
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum München, Munich, Germany
- German Center for Diabetes Research (DZD), Munich, Germany
| | - Jiaqi Gao
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Katharina Heinzelmann
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Jutta Lintelmann
- Joint Mass Spectrometry Centre, Comprehensive Molecular Analytics, Helmholtz Zentrum München, Munich, Germany
| | - Martin Irmler
- Institute of Experimental Genetics, Helmholtz Zentrum München, Munich, Germany
| | - Stefan Pfeiffer
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum München, Munich, Germany
| | - Michael Schloter
- Research Unit Comparative Microbiome Analysis, Helmholtz Zentrum München, Munich, Germany
| | - Ralf Zimmermann
- Joint Mass Spectrometry Centre, Comprehensive Molecular Analytics, Helmholtz Zentrum München, Munich, Germany
- University of Rostock, Rostock, Germany
| | - Martin Hrabé de Angelis
- German Center for Diabetes Research (DZD), Munich, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, Munich, Germany
- Chair of Experimental Genetics, Technische Universität München, Freising-Weihenstephan, Germany
| | - Johannes Beckers
- German Center for Diabetes Research (DZD), Munich, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, Munich, Germany
- Chair of Experimental Genetics, Technische Universität München, Freising-Weihenstephan, Germany
| | - Jerzy Adamski
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum München, Munich, Germany
- German Center for Diabetes Research (DZD), Munich, Germany
- Chair of Experimental Genetics, Technische Universität München, Freising-Weihenstephan, Germany
| | - Hasan Bayram
- Department of Chest Diseases, School of Medicine, University of Gaziantep, Gaziantep, Turkey
- School of Medicine, Koç University, Istanbul, Turkey
| | - Oliver Eickelberg
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado, Denver, CO, USA
| | - Ali Önder Yildirim
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Munich, Germany
- Member of the German Center for Lung Research (DZL), Munich, Germany
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3
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TRPC3 amplifies B-cell receptor-induced ERK signalling via protein kinase D-dependent Rap1 activation. Biochem J 2015; 473:201-10. [PMID: 26554024 DOI: 10.1042/bj20150596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 11/09/2015] [Indexed: 11/17/2022]
Abstract
Sustained activation of extracellular-signal-regulated kinase (ERK) has an important role in the decision regarding the cell fate of B-lymphocytes. Recently, we demonstrated that the diacylglycerol-activated non-selective cation channel canonical transient receptor potential 3 (TRPC3) is required for the sustained ERK activation induced by the B-cell receptor. However, the signalling mechanism underlying TRPC3-mediated ERK activation remains elusive. In the present study, we have shown that TRPC3 mediates Ca(2+) influx to sustain activation of protein kinase D (PKD) in a protein kinase C-dependent manner in DT40 B-lymphocytes. The later phase of ERK activation depends on the small G-protein Rap1, known as a downstream target of PKD, whereas the earlier phase of ERK activation depends on the Ras protein. It is of interest that sustained ERK phosphorylation is required for the full induction of the immediate early gene Egr-1 (early growth response 1). These results suggest that TRPC3 reorganizes the BCR signalling complex by switching the subtype of small G-proteins to sustain ERK activation in B-lymphocytes.
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4
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Abstract
My Ph.D. thesis in the laboratory of Severo Ochoa at New York University School of Medicine in 1962 included the determination of the nucleotide compositions of codons specifying amino acids. The experiments were based on the use of random copolyribonucleotides (synthesized by polynucleotide phosphorylase) as messenger RNA in a cell-free protein-synthesizing system. At Yale University, where I joined the faculty, my co-workers and I first studied the mechanisms of protein synthesis. Thereafter, we explored the interferons (IFNs), which were discovered as antiviral defense agents but were revealed to be components of a highly complex multifunctional system. We isolated pure IFNs and characterized IFN-activated genes, the proteins they encode, and their functions. We concentrated on a cluster of IFN-activated genes, the p200 cluster, which arose by repeated gene duplications and which encodes a large family of highly multifunctional proteins. For example, the murine protein p204 can be activated in numerous tissues by distinct transcription factors. It modulates cell proliferation and the differentiation of a variety of tissues by binding to many proteins. p204 also inhibits the activities of wild-type Ras proteins and Ras oncoproteins.
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Affiliation(s)
- Peter Lengyel
- From the Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520
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5
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Wheeler ML, Dong MB, Brink R, Zhong XP, DeFranco AL. Diacylglycerol kinase ζ limits B cell antigen receptor-dependent activation of ERK signaling to inhibit early antibody responses. Sci Signal 2013; 6:ra91. [PMID: 24129701 DOI: 10.1126/scisignal.2004189] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Signaling downstream of the B cell antigen receptor (BCR) is tightly regulated to enable cells to gauge the strength and duration of antigen-receptor interactions and to respond appropriately. We investigated whether metabolism of the second messenger diacylglycerol (DAG) by members of the family of DAG kinases (DGKs) played a role in modulating the magnitude of signaling by DAG downstream of the BCR. In the absence of DGKζ, the threshold for BCR signaling, measured as activation of the Ras-extracellular signal-regulated kinase (ERK) pathway, was markedly reduced in mature follicular B cells, which resulted in enhanced responses to antigen in vitro and in vivo. Inhibition of DAG signaling by DGKζ limited the number of antibody-secreting cells that were generated early in response to T cell-independent type 2 antigens, as well as to T cell-dependent antigens. Furthermore, the effect of loss of DGKζ closely resembled the effect of increasing the affinity of the BCR for antigen during the T cell-dependent antibody response. These results suggest that the magnitude of DAG signaling is important for translating the affinity of the BCR for antigen into the amount of antibody produced during the early stages of an immune response.
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Affiliation(s)
- Matthew L Wheeler
- 1Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
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6
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Suppression of the LMP2A target gene, EGR-1
, protects Hodgkin's lymphoma cells from entry to the EBV lytic cycle. J Pathol 2013; 230:399-409. [DOI: 10.1002/path.4198] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 03/22/2013] [Accepted: 04/11/2013] [Indexed: 02/06/2023]
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7
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Murn J, Alibert O, Wu N, Tendil S, Gidrol X. Prostaglandin E2 regulates B cell proliferation through a candidate tumor suppressor, Ptger4. ACTA ACUST UNITED AC 2008; 205:3091-103. [PMID: 19075289 PMCID: PMC2605229 DOI: 10.1084/jem.20081163] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
B cell receptor (BCR) signaling contributes to the pathogenesis of B cell malignancies, and most B cell lymphomas depend on BCR signals for survival. Identification of genes that restrain BCR-mediated proliferation is therefore an important goal toward improving the therapy of B cell lymphoma. Here, we identify Ptger4 as a negative feedback regulator of proliferation in response to BCR signals and show that its encoded EP4 receptor is a principal molecule conveying the growth-suppressive effect of prostaglandin E2 (PGE2). Stable knockdown of Ptger4 in B cell lymphoma markedly accelerated tumor spread in mice, whereas Ptger4 overexpression yielded significant protection. Mechanistically, we show that the intrinsic activity of Ptger4 and PGE2–EP4 signaling target a similar set of activating genes, and find Ptger4 to be significantly down-regulated in human B cell lymphoma. We postulate that Ptger4 functions in B cells as a candidate tumor suppressor whose activity is regulated by PGE2 in the microenvironment. These findings suggest that targeting EP4 receptor for prostaglandin may present a novel strategy for treatment of B cell malignancies.
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Affiliation(s)
- Jernej Murn
- CEA, DSV, Institut de Radiobiologie Cellulaire et Moléculaire, Laboratoire d'Exploration Fonctionnelle des Génomes, Evry, France
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8
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Luan Y, Lengyel P, Liu CJ. p204, a p200 family protein, as a multifunctional regulator of cell proliferation and differentiation. Cytokine Growth Factor Rev 2008; 19:357-69. [PMID: 19027346 DOI: 10.1016/j.cytogfr.2008.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The interferon-inducible p200 family comprises a group of homologous mouse and human proteins. Most of these have an N-terminal DAPIN domain and one or two partially conserved, 200 amino acid long C-terminal domains (designated as 200X domain). These proteins play important roles in the regulation of cell proliferation, tissue differentiation, apoptosis and senescence. p200 family proteins are involved also in autoimmunity and the control of tumor growth. These proteins function by binding to various target proteins (e.g. transcription factors, signaling proteins, oncoproteins and tumor suppressor proteins) and modulating target activity. This review concentrates on p204, a murine member of the family and its roles in regulating cell proliferation, cell and tissue differentiation (e.g. of skeletal muscle myotubes, beating cardiac myocytes, osteoblasts, chondrocytes and macrophages) and signaling by Ras proteins. The expression of p204 in various tissues as promoted by tissue-specific transcription factors, its distribution among subcellular compartments, and the controls of these features are also discussed.
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Affiliation(s)
- Yi Luan
- Department of Orthopaedic Surgery, New York University School of Medicine, New York, 10003, United States
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9
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Lengyel P. From RNase L to the Multitalented p200 Family Proteins: An Exploration of the Modes of Interferon Action. J Interferon Cytokine Res 2008; 28:273-81. [DOI: 10.1089/jir.2008.3993.hp] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Peter Lengyel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
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10
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Abstract
The murine p200 family protein, p204, modulates cell proliferation and tissue differentiation. Many of its activities are exerted in the nucleus. However, in cardiac myocytes, p204 accumulated in the cytoplasm. A yeast two-hybrid assay revealed a p204-cytoplasmic Ras protein interaction. This was confirmed (i) by coimmunoprecipitation of p204 with Ras in mouse heart extract and with endogenous or ectopic H-Ras and K-Ras in cell lysates as well as (ii) by binding of purified H-Ras-GTP to purified p204 in vitro. p204 inhibited (i) the cleavage of RasGTP to RasGDP by RasGAP; (ii) the binding to RasGTP of Raf-1, phosphatidylinositol 3-kinase, and Ral-GDS, effectors of Ras signaling; and (iii) activation by the Ras pathway of the phosphorylation and thus activation of downstream targets (e.g. MEK, Akt, and p38 MAPK). Oncogenic Ras expression triggered the phosphorylation and translocation of p204 from the nucleus to the cytoplasm. This is expected to increase the interaction between the two proteins. Translocation triggered by Ras oncoprotein was blocked by the LY294002 inhibitor of phosphatidylinositol 3-kinase. Ras did not promote phosphorylation or translocation to the cytoplasm of mutated p204 in which serine 179 was replaced by alanine. p204 overexpression inhibited the anchorage-independent proliferation of cells expressing Ras(Q61L) oncoprotein. Ras oncoprotein triggered in MEF3T3 cells the rearrangement of the actin cytoskeleton and the enhancement of cell migration through a membrane. Overexpression of p204 inhibited both. Ras oncoprotein or activated, wild-type Ras was described to increase Egr-1 transcription factor expression. We report that a sequence in the gene encoding p204 bound Egr-1, and Egr-1 activated p204 expression. Ras oncoprotein or activated wild-type Ras increased the expression in 3T3 cells of p204 together with that of Egr-1. Furthermore, the activation of expression of a single copy of K-ras oncogene in cultured murine embryonic cells induced the expression of a high level of p204 as well as its distribution between the nuclei and the cytoplasm. Thus, p204 may serve as a negative feedback inhibitor of Ras activity.
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Affiliation(s)
- Bo Ding
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8024, USA
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11
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de Gorter DJJ, Vos JCM, Pals ST, Spaargaren M. The B cell antigen receptor controls AP-1 and NFAT activity through Ras-mediated activation of Ral. THE JOURNAL OF IMMUNOLOGY 2007; 178:1405-14. [PMID: 17237388 DOI: 10.4049/jimmunol.178.3.1405] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Signaling by the BCR involves activation of several members of the Ras superfamily of small GTPases, among which is Ras itself. Ras can control the activity of multiple effectors, including Raf, PI3K, and guanine nucleotide exchange factors for the small GTPase Ral. Ras, Raf, and PI3K have been implicated in a variety of processes underlying B cell development, differentiation, and function; however, the role of Ral in B lymphocytes remains to be established. In this study, we show that Ral is activated upon BCR stimulation in human tonsillar and mouse splenic B lymphocytes and in B cell lines. Using signaling molecule-deficient B cells, we demonstrate that this activation is mediated by Lyn and Syk, Btk, phospholipase C-gamma2, and inositol-1,4,5-trisphosphate receptor-mediated Ca(2+) release. In addition, although Ral can be activated by Ras-independent mechanisms, we demonstrate that BCR-controlled activation of Ral is dependent on Ras. By means of expression of the dominant-negative mutants RasN17 and RalN28, or of RalBPDeltaGAP, a Ral effector mutant which sequesters active Ral, we show that Ras and Ral mediate BCR-controlled transcription of c-fos. Furthermore, while not involved in NF-kappaB activation, Ras and Ral mediate BCR-controlled activation of JUN/ATF2 and NFAT transcription factors. Taken together, our data show that Ral is activated upon BCR stimulation and mediates BCR-controlled activation of AP-1 and NFAT transcription factors. These findings suggest that Ral plays an important role in B cell development and function.
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Affiliation(s)
- David J J de Gorter
- Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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12
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Abstract
In adult mammals, bone marrow pluripotent hematopoietic stem cells generate B lymphoid-specified progeny that progress through a series of well-characterized stages before generating B-cell receptor expressing B lymphocytes. These functionally immature B lymphocytes then migrate to the spleen wherein they differentiate through transitional stages into follicular or marginal zone B lymphocytes capable of responding to T-dependent and -independent antigens, respectively. During the terminal stages of B lymphocyte development in the bone marrow, as well as immediately following egress into the peripheral compartments, B lymphocytes are counterselected to eliminate B lymphocytes with potentially dangerous self-reactivity. These developmental and selection events in the bone marrow and periphery are dependent on the integration of intrinsic genetic programs with extrinsic microenvironmental signals that drive progenitors toward increasing B lineage commitment and maturation. This chapter provides a comprehensive overview of the various stages of primary and secondary B lymphocyte development with an emphasis on the selection processes that affect decisions at critical checkpoints. Our intent is to stress the concept that at many steps in the developmental process leading to a mature immunocompetent B lymphocyte, B lineage cells are integrating multiple and different signaling inputs that are translated into specific and appropriate cell fate decisions.
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MESH Headings
- Aging
- Animals
- Antigens, Differentiation, B-Lymphocyte/analysis
- B-Lymphocyte Subsets/cytology
- B-Lymphocyte Subsets/immunology
- B-Lymphocyte Subsets/physiology
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- B-Lymphocytes/physiology
- Bone Marrow Cells/cytology
- Bone Marrow Cells/immunology
- Bone Marrow Cells/physiology
- Cell Lineage
- Humans
- Lymphopoiesis/genetics
- Models, Immunological
- Precursor Cells, B-Lymphoid/cytology
- Precursor Cells, B-Lymphoid/immunology
- Precursor Cells, B-Lymphoid/physiology
- Receptors, Antigen, B-Cell/immunology
- Receptors, Antigen, B-Cell/metabolism
- Recombination, Genetic
- Signal Transduction
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Affiliation(s)
- John G Monroe
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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13
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Ke J, Gururajan M, Kumar A, Simmons A, Turcios L, Chelvarajan RL, Cohen DM, Wiest DL, Monroe JG, Bondada S. The role of MAPKs in B cell receptor-induced down-regulation of Egr-1 in immature B lymphoma cells. J Biol Chem 2006; 281:39806-18. [PMID: 17065146 DOI: 10.1074/jbc.m604671200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cross-linking of the B cell receptor (BCR) on the immature B lymphoma cell line BKS-2 induces growth inhibition and apoptosis accompanied by rapid down-regulation of the immediate-early gene egr-1. In these lymphoma cells, egr-1 is expressed constitutively and has a prosurvival role, as Egr-1-specific antisense oligonucleotides or expression of a dominant-negative inhibitor of Egr-1 also prevented the growth of BKS-2 cells. Moreover, enhancement of Egr-1 protein with phorbol 12-myristate 13-acetate or an egr-1 expression vector rescued BKS-2 cells from BCR signal-induced growth inhibition. Nuclear run-on and mRNA stability assays indicated that BCR-derived signals act at the transcriptional level to reduce egr-1 expression. Inhibitors of ERK and JNK (but not of p38 MAPK) reduced egr-1 expression at the protein level. Transcriptional regulation appears to have a role because egr-1 promoter-driven luciferase expression was reduced by ERK and JNK inhibitors. Promoter truncation experiments suggested that several serum response elements are required for MAPK-mediated egr-1 expression. Our study suggests that BCR signals reduce egr-1 expression by inhibiting activation of ERK and JNK. Unlike ERK and JNK, p38 MAPK reduces constitutive expression of egr-1. Unlike the immature B lymphoma cells, normal immature B cells did not exhibit constitutive MAPK activation. BCR-induced MAPK activation was modest and transient with a small increase in egr-1 expression in normal immature B cells consistent with their inability to proliferate in response to BCR cross-linking.
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Affiliation(s)
- Jiyuan Ke
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky 40536, USA
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14
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Abstract
The developmental program that commits a hematopoietic stem cell to the B lymphocyte lineage employs transcriptional regulators to enable the assembly of an antigen receptor complex with a useful specificity and with signalling competence. Once a naive IgM+ B cell is generated, it must correctly integrate signals from the antigen receptor with those from cytokine receptors and co-receptors delivering T cell help. The B cell responds through the regulated expression of genes that implement specific cell expansion and differentiation, secretion of high levels of high-affinity antibody, and generation of long-term memory. The transcriptional regulators highlighted in this chapter are those for which genetic evidence of function in IgM+ B cells in vivo has been provided, often in the form of mutant mice generated by conventional or conditional gene targeting. A critical developmental step is the maturation of bone marrow emigrant "transitional" B cells into the mature, long-lived cells of the periphery, and a number of the transcription factors discussed here impact on this process, yielding B cells with poor mitogenic responses in vitro. For mature B cells, it is clear that not only the nature, but the duration and amplitude of an activating signal are major determinants of the transcription factor activities enlisted, and so the ultimate outcome. The current challenge is the identification of the target genes that are activated to implement the correct response, so that we may more precisely and safely manipulate B cell behavior to predictably and positively influence humoral immune responses.
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Affiliation(s)
- L M Corcoran
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia.
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15
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Shaw PE, Saxton J. Ternary complex factors: prime nuclear targets for mitogen-activated protein kinases. Int J Biochem Cell Biol 2003; 35:1210-26. [PMID: 12757758 DOI: 10.1016/s1357-2725(03)00031-1] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Ternary complex factors (TCFs), a subgroup of the ETS protein family, were first described in the context of c-fos gene regulation. Subsequently, their early identification as nuclear targets for mitogen-activated protein kinases served to exemplify the fundamental links in eukaryotic cells between growth factor-mediated signalling pathways and gene control. This article provides an overview of recent work on ternary complex factors, addressing their expression and molecular structure, as well as how selective interactions with members of other protein families serve to up-1 regulate or restrict their activity. Although only one genetic study on ternary complex factors has been published to date, unravelling of the underlying molecular events provides a basis for tentative predictions about their biological roles in mammalian organisms.
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Affiliation(s)
- Peter E Shaw
- Queen's Medical Centre, School of Biomedical Sciences, University of Nottingham, UK.
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16
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Davidson D, Veillette A. PTP-PEST, a scaffold protein tyrosine phosphatase, negatively regulates lymphocyte activation by targeting a unique set of substrates. EMBO J 2001; 20:3414-26. [PMID: 11432829 PMCID: PMC125513 DOI: 10.1093/emboj/20.13.3414] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
There is increasing interest in elucidating the mechanisms involved in the negative regulation of lymphocyte activation. Herein, we show that the cytosolic protein tyrosine phosphatase PTP-PEST is expressed abundantly in a wide variety of haemopoietic cell types, including B cells and T cells. In a model B-cell line, PTP-PEST was found to be constitutively associated with several signalling molecules, including Shc, paxillin, Csk and Cas. The interaction between Shc and PTP-PEST was augmented further by antigen receptor stimulation. Overexpression studies, antisense experiments and structure-function analyses provided evidence that PTP-PEST is an efficient negative regulator of lymphocyte activation. This function correlated with the ability of PTP-PEST to induce dephosphorylation of Shc, Pyk2, Fak and Cas, and inactivate the Ras pathway. Taken together, these data suggest that PTP-PEST is a novel and unique component of the inhibitory signalling machinery in lymphocytes.
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Affiliation(s)
- Dominique Davidson
- Laboratory of Molecular Oncology, IRCM, 110 Pine Avenue West, Montréal, Québec H2W 1R7, McGill Cancer Centre and Departments of Medicine and Biochemistry, McGill University, 3655 Drummond Street, Montréal, Québec H3G 1Y6, Canada Corresponding author e-mail:
| | - André Veillette
- Laboratory of Molecular Oncology, IRCM, 110 Pine Avenue West, Montréal, Québec H2W 1R7, McGill Cancer Centre and Departments of Medicine and Biochemistry, McGill University, 3655 Drummond Street, Montréal, Québec H3G 1Y6, Canada Corresponding author e-mail:
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17
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Richards JD, Davé SH, Chou CH, Mamchak AA, DeFranco AL. Inhibition of the MEK/ERK signaling pathway blocks a subset of B cell responses to antigen. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:3855-64. [PMID: 11238629 DOI: 10.4049/jimmunol.166.6.3855] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Signal transduction initiated by B cell Ag receptor (BCR) cross-linking plays an important role in the development and activation of B cells. Therefore, considerable effort has gone into determining the biochemical signaling events initiated by the BCR and delineating which events participate in specific biological responses to Ag. We used two inhibitors of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) 1 and MEK2, PD98059, and U0126, to assess the role the Ras-mitogen-activated protein kinase pathway plays in several BCR-induced responses. PD98059 or U0126 treatment substantially inhibited the BCR-induced activation of the extracellular signal-regulated kinase (ERK) forms of mitogen-activated protein kinase in the immature B cell line WEHI-231, in immature splenic B cells, and in mature splenic B cells. However, MEK-ERK inhibition did not block BCR-induced growth arrest or apoptosis of WEHI-231 cells or apoptosis of immature splenic B cells, indicating that the MEK-ERK pathway is not required for these events. In contrast, PD98059 and U0126 treatment did inhibit the up-regulation of specific BCR-induced proteins, including the transcription factor Egr-1 in WEHI-231 and mature splenic B cells, and the CD44 adhesion molecule and CD69 activation marker in mature splenic B cells. Moreover, both inhibitors suppressed BCR-induced proliferation of mature splenic B cells, in the absence and in the presence of IL-4. Therefore, activation of the MEK-ERK pathway is necessary for a subset of B cell responses to Ag.
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MESH Headings
- Animals
- Antigens/immunology
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Apoptosis/drug effects
- Apoptosis/immunology
- B-Lymphocyte Subsets/cytology
- B-Lymphocyte Subsets/drug effects
- B-Lymphocyte Subsets/enzymology
- B-Lymphocyte Subsets/immunology
- Butadienes/pharmacology
- Cell Differentiation/drug effects
- Cell Differentiation/immunology
- Cell Division/drug effects
- Cell Division/immunology
- Cell Separation
- Cells, Cultured
- DNA-Binding Proteins/antagonists & inhibitors
- DNA-Binding Proteins/biosynthesis
- Early Growth Response Protein 1
- Enzyme Activation/drug effects
- Enzyme Activation/immunology
- Enzyme Inhibitors/pharmacology
- Female
- Flavonoids/pharmacology
- Growth Inhibitors/pharmacology
- Hyaluronan Receptors/biosynthesis
- Immediate-Early Proteins
- Lectins, C-Type
- Lymphocyte Activation/drug effects
- MAP Kinase Kinase Kinases/antagonists & inhibitors
- MAP Kinase Kinase Kinases/metabolism
- MAP Kinase Kinase Kinases/physiology
- MAP Kinase Signaling System/drug effects
- MAP Kinase Signaling System/immunology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/metabolism
- Mitogen-Activated Protein Kinases/physiology
- Nitriles/pharmacology
- Receptors, Antigen, B-Cell/antagonists & inhibitors
- Receptors, Antigen, B-Cell/physiology
- Spleen/cytology
- Spleen/immunology
- Transcription Factors/antagonists & inhibitors
- Transcription Factors/biosynthesis
- Tumor Cells, Cultured
- Up-Regulation/drug effects
- Up-Regulation/immunology
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Affiliation(s)
- J D Richards
- Department of Microbiology and Immunology, G. W. Hooper Foundation, University of California, San Francisco, CA 94143, USA
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18
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Han SS, Chung ST, Robertson DA, Ranjan D, Bondada S. Curcumin causes the growth arrest and apoptosis of B cell lymphoma by downregulation of egr-1, c-myc, bcl-XL, NF-kappa B, and p53. Clin Immunol 1999; 93:152-61. [PMID: 10527691 DOI: 10.1006/clim.1999.4769] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It has been well known that curcumin is a powerful inhibitor of proliferation of several tumor cells. However, the molecular basis of the anti-proliferative effect of curcumin has not been investigated in detail. In this paper, we present evidence to show that curcumin inhibited proliferation of a variety of B lymphoma cells. At low concentrations curcumin inhibited the proliferation of BKS-2, an immature B cell lymphoma, more effectively than that of normal B lymphocytes and caused the apoptosis of BKS-2 cells in a dose- and time-dependent manner. Furthermore, curcumin downregulated the expression of survival genes egr-1, c-myc, and bcl-X(L) as well as the tumor suppressor gene p53 in B cells. In addition, NF-kappaB binding activity was also downregulated almost completely by curcumin. Stimulation with CpG oligonucleotides or anti-CD40 overcame growth inhibition induced by low concentrations of curcumin. Our results suggest that curcumin caused the growth arrest and apoptosis of BKS-2 immature B cell lymphoma by downregulation of growth and survival promoting genes.
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Affiliation(s)
- S S Han
- Department of Microbiology and Immunology, Department of General Surgery, Lexington, Kentucky 40536, USA
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19
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Gold MR. Intermediary signaling effectors coupling the B-cell receptor to the nucleus. Curr Top Microbiol Immunol 1999; 245:77-134. [PMID: 10533311 DOI: 10.1007/978-3-642-57066-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M R Gold
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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20
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Rolli M, Kotlyarov A, Sakamoto KM, Gaestel M, Neininger A. Stress-induced stimulation of early growth response gene-1 by p38/stress-activated protein kinase 2 is mediated by a cAMP-responsive promoter element in a MAPKAP kinase 2-independent manner. J Biol Chem 1999; 274:19559-64. [PMID: 10391889 DOI: 10.1074/jbc.274.28.19559] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The p38/stress-activated protein kinase2 (p38/SAPK2) is activated by cellular stress and proinflammatory cytokines. Several transcription factors have been reported to be regulated by p38/SAPK2, and this kinase is involved in the control of expression of various genes. In human Jurkat T-cells, induction of the early growth response gene-1 (egr-1) by anisomycin is completely inhibited by SB203580, a specific inhibitor of p38/SAPK2a and -b. Northern blot and reporter gene experiments indicate that this block is at the level of mRNA biosynthesis. Using mutants of the egr-1 promoter, we demonstrate that a distal cAMP-responsive element (CRE; nucleotides -134 to -126) is necessary to control egr-1 induction by p38/SAPK2. Pull-down assays indicate that phospho-CRE binding protein (CREB) and phospho-activating transcription factor-1 (ATF1) bind to this element in a p38/SAPK2-dependent manner. In response to anisomycin, two known CREB kinases downstream to p38/SAPK2, MAPKAP kinase 2 (MK2) and mitogen- and stress-activated kinase 1 (MSK1), show increased activity. However, in MK2 -/- fibroblasts derived from mice carrying a disruption of the MK2 gene, the phosphorylation of CREB and ATF1 and the expression of egr-1 reach levels comparable with wild type cells. This finding excludes MK2 as an involved enzyme. We conclude that egr-1 induction by anisomycin is mediated by p38/SAPK2 and probably by MSK1. Phosphorylated CREB and ATF1 then bind to the CRE of the egr-1 promoter and cause a stress-dependent transcriptional activation of this gene.
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Affiliation(s)
- M Rolli
- Martin-Luther-University Halle-Wittenberg, Innovationskolleg Zellspezialisierung, Hoher Weg 8, D-06120 Halle, Germany
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21
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Altman A, Deckert M. The function of small GTPases in signaling by immune recognition and other leukocyte receptors. Adv Immunol 1999; 72:1-101. [PMID: 10361572 DOI: 10.1016/s0065-2776(08)60017-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- A Altman
- Division of Cell Biology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA
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22
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Dinkel A, Warnatz K, Ledermann B, Rolink A, Zipfel PF, Bürki K, Eibel H. The transcription factor early growth response 1 (Egr-1) advances differentiation of pre-B and immature B cells. J Exp Med 1998; 188:2215-24. [PMID: 9858508 PMCID: PMC2212439 DOI: 10.1084/jem.188.12.2215] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In mature B lymphocytes, the zinc finger transcription factor early growth response 1 (Egr-1) is one of the many immediate-early genes induced upon B cell antigen receptor engagement. However, its role during earlier stages of lymphopoiesis has remained unclear. By examining bone marrow B cell subsets, we found Egr-1 transcripts in pro/pre-B and immature B lymphocytes, and Egr-1 protein in pro/pre-B-I cells cultivated on stroma cells in the presence of interleukin (IL)-7. In recombinase-activating gene (RAG)-2-deficient mice overexpressing an Egr-1 transgene in the B lymphocyte lineage, pro/pre-B-I cells could differentiate past a developmental block at the B220(low) BP-1(-) stage to the stage of B220(low) BP-1(+) pre-B-I cells, but not further to the B220(low) BP-1(+) CD25(+) stage of pre-B-II cells. Therefore, during early B lymphopoiesis progression from the B220(low) BP-1(-) IL-2R- pro/pre-B-I stage to the B220(low) BP-1(+) IL-2R+ pre-B-II stage seems to occur in at least two distinct steps, and the first step to the stage of B220(low) BP-1(+) pre-B-I cells can be promoted by the overexpression of Egr-1 alone. Wild-type mice expressing an Egr-1 transgene had increased proportions of mature immunoglobulin (Ig)M+ B220(high) and decreased proportions of immature IgM+ B220(low) bone marrow B cells. Since transgenic and control precursor B cells show comparable proliferation patterns, overexpression of Egr-1 seems also to promote entry into the mature B cell stage. Analysis of changes in the expression pattern of potential Egr-1 target genes revealed that Egr-1 enhances the expression of the aminopeptidase BP-1/6C3 in pre-B and immature B cells and upregulates expression of the orphan nuclear receptor nur77 in IgM+ B cells.
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Affiliation(s)
- A Dinkel
- Clinical Research Unit for Rheumatology, Division of Rheumatology and Clinical Immunology, University Hospital Freiburg, D-79106 Freiburg, Germany
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23
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Li X, Carter RH. Convergence of CD19 and B Cell Antigen Receptor Signals at MEK1 in the ERK2 Activation Cascade. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.11.5901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
CD19 plays a critical role in regulating B cell responses to Ag. We have studied the mechanism by which coligation of CD19 and the B cell Ag receptor, membrane Ig (mIg), augments signal transduction, including synergistic enhancement of release of intracellular Ca2+ and extracellular signal-regulated protein kinase 2 (ERK2) activation, in Daudi human B lymphoblastoid cells. The pathway leading to ERK2 activation was further dissected to determine how signals derived from CD19 and mIgM interact. The best-defined pathway, known to be activated by mIgM, consists of the sequential activation of the mitogen-activated protein kinase (MAPK) cascade that includes Ras, Raf, MAPK kinase 1 (MEK1), and ERK2. Ligation of CD19 alone had little effect on these. CD19-mIgM coligation did not increase activation of Ras or Raf beyond that induced by ligation of mIgM alone. In contrast, coligation resulted in synergistic activation of MEK1. Furthermore, synergistic activation of ERK2 occurred in the absence of changes in intracellular Ca2+, and was not blocked by inhibition of protein kinase C activity and represents a separate pathway by which CD19 regulates B cell function. Thus, the CD19-dependent signal after CD19-mIgM coligation converges with that generated by mIgM at MEK1. The intermediate kinases in the MAPK cascade leading to ERK2 integrate signals from lymphocyte coreceptors.
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Affiliation(s)
| | - Robert H. Carter
- *Medicine and
- †Microbiology, University of Alabama, Birmingham, AL 35294; and
- ‡Birmingham Veterans Affairs Medical Center, Birmingham, AL 35294
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24
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Modulation and Functional Involvement of CB2 Peripheral Cannabinoid Receptors During B-Cell Differentiation. Blood 1998. [DOI: 10.1182/blood.v92.10.3605] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractTwo subtypes of G-protein–coupled cannabinoid receptors have been identified to date: the CB1 central receptor subtype, which is mainly expressed in the brain, and the CB2 peripheral receptor subtype, which appears particularly abundant in the immune system. We investigated the expression of CB2 receptors in leukocytes using anti-CB2 receptor immunopurified polyclonal antibodies. We showed that peripheral blood and tonsillar B cells were the leukocyte subsets expressing the highest amount of CB2 receptor proteins. Dual-color confocal microscopy performed on tonsillar tissues showed a marked expression of CB2 receptors in mantle zones of secondary follicles, whereas germinal centers (GC) were weakly stained, suggesting a modulation of this receptor during the differentiation stages from virgin B lymphocytes to memory B cells. Indeed, we showed a clear downregulation of CB2 receptor expression during B-cell differentiation both at transcript and protein levels. The lowest expression was observed in GC proliferating centroblasts. Furthermore, we investigated the effect of the cannabinoid agonist CP55,940 on the CD40-mediated proliferation of both virgin and GC B-cell subsets. We found that CP55,940 enhanced the proliferation of both subsets and that this enhancement was blocked by the CB2 receptor antagonist SR 144528 but not by the CB1 receptor antagonist SR 141716. Finally, we observed that CB2 receptors were dramatically upregulated in both B-cell subsets during the first 24 hours of CD40-mediated activation. These data strongly support an involvement of CB2 receptors during B-cell differentiation.
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25
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Abstract
Two subtypes of G-protein–coupled cannabinoid receptors have been identified to date: the CB1 central receptor subtype, which is mainly expressed in the brain, and the CB2 peripheral receptor subtype, which appears particularly abundant in the immune system. We investigated the expression of CB2 receptors in leukocytes using anti-CB2 receptor immunopurified polyclonal antibodies. We showed that peripheral blood and tonsillar B cells were the leukocyte subsets expressing the highest amount of CB2 receptor proteins. Dual-color confocal microscopy performed on tonsillar tissues showed a marked expression of CB2 receptors in mantle zones of secondary follicles, whereas germinal centers (GC) were weakly stained, suggesting a modulation of this receptor during the differentiation stages from virgin B lymphocytes to memory B cells. Indeed, we showed a clear downregulation of CB2 receptor expression during B-cell differentiation both at transcript and protein levels. The lowest expression was observed in GC proliferating centroblasts. Furthermore, we investigated the effect of the cannabinoid agonist CP55,940 on the CD40-mediated proliferation of both virgin and GC B-cell subsets. We found that CP55,940 enhanced the proliferation of both subsets and that this enhancement was blocked by the CB2 receptor antagonist SR 144528 but not by the CB1 receptor antagonist SR 141716. Finally, we observed that CB2 receptors were dramatically upregulated in both B-cell subsets during the first 24 hours of CD40-mediated activation. These data strongly support an involvement of CB2 receptors during B-cell differentiation.
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26
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Deehan MR, Klaus GG, Holman MJ, Harnett W, Harnett MM. MAPkinase: a second site of G-protein regulation of B-cell activation via the antigen receptors. Immunol Suppl 1998; 95:169-77. [PMID: 9824472 PMCID: PMC1364301 DOI: 10.1046/j.1365-2567.1998.00591.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ligation of the antigen receptors on B cells transduces transmembrane signals leading to the induction of DNA synthesis. We now show that a pertussis toxin-sensitive heterotrimeric G-protein(s) of the Gi class plays a key role in the regulation of surface immunoglobulin (sIg)-mediated DNA synthesis in B cells. This site of G-protein regulation is distinct from that we have previously reported to govern the coupling of the antigen receptors on B cells to the phospholipase C-mediated hydrolysis of phosphatidylinositol-4,5-bisphosphate. We have, moreover, identified a candidate target for this new G-protein regulation by showing that mitogen-activating protein kinase (MAPkinase) activity, which plays a key role in the transduction of sIg-mediated proliferative signals in B cells, is abrogated by pre-exposure to pertussis toxin that covalently modifies and inactivates heterotrimeric G-proteins of the Gi class. Furthermore, our data suggest that this pertussis toxin-sensitive G-protein couples the antigen receptors to MAPkinase activation, at least in part, by regulating sIg-coupling to Lyn, Syk and perhaps Blk and Fyn activity, results consistent with studies in other systems which show that classical G-protein-coupled receptors recruit such protein tyrosine kinases to tranduce MAPkinase activation. Interestingly, however, this G-protein plays no apparent role in the control of up-regulation of major histocompatibility complex class II expression on B cells, suggesting that such G-protein-regulated-tyrosine kinase and MAPkinase activation is not required for the induction of this biological response following antigen receptor ligation.
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Affiliation(s)
- M R Deehan
- Department of Immunology, University of Strathclyde, Glasgow
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27
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Chan VW, Lowell CA, DeFranco AL. Defective negative regulation of antigen receptor signaling in Lyn-deficient B lymphocytes. Curr Biol 1998; 8:545-53. [PMID: 9601638 DOI: 10.1016/s0960-9822(98)70223-4] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND To elucidate the role of the Src family kinase Lyn in B cell receptor (BCR) signaling, we and others previously generated lyn-/- mice and analyzed their B cell responses. Although the initiation of BCR signaling in lyn-/- B cells is delayed, BCR-induced ERK2 activation and proliferation are enhanced. As the co-receptors Fc gamma RIIb1 and CD22 have been shown to be negative regulators of BCR signaling, we have now examined their functional roles in lyn-/- B cells. RESULTS B cells from lyn-/- mice have increased expression of the protein product of the early response gene egr-1, enhanced activation of Jun N-terminal kinase (JNK), and elevated calcium responses upon BCR cross-linking. Tyrosine phosphorylation of Fc gamma RIIb1 in lyn-/- B cells was reduced but negative regulation of the BCR signal by Fc gamma RIIb1 was only modestly impaired. In contrast, tyrosine phosphorylation of CD22 was greatly decreased in lyn-/- B cells, correlating with the inability of CD22 to downregulate the BCR-induced calcium response in these cells. Surprisingly, CD22 remains capable of regulating the ERK2 and JNK pathways in lyn-/- B cells, which may relate to the small residual increase in BCR-induced CD22 phosphorylation. CONCLUSIONS BCR signal initiation and negative regulation by Fc gamma RIIb1 is not critically dependent on Lyn. In contrast, Lyn plays a particularly important role in the tyrosine phosphorylation of CD22 and in the consequent inhibition of BCR-induced calcium influx. The net result of the Lyn deficiency in B cells is hyperresponsiveness to antigen stimulation, which may explain the autoimmunity observed in lyn-/- mice.
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MESH Headings
- Animals
- Antigens, CD/biosynthesis
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/metabolism
- B-Lymphocytes/metabolism
- Calcium/metabolism
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cell Adhesion Molecules
- Cells, Cultured
- Enzyme Activation
- Gene Deletion
- JNK Mitogen-Activated Protein Kinases
- Lectins
- Mice
- Mitogen-Activated Protein Kinase 1
- Mitogen-Activated Protein Kinase 9
- Mitogen-Activated Protein Kinases
- Protein Kinases/metabolism
- Rabbits
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/physiology
- Receptors, IgG/biosynthesis
- Sialic Acid Binding Ig-like Lectin 2
- Signal Transduction
- Tyrosine/metabolism
- src-Family Kinases/genetics
- src-Family Kinases/physiology
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Affiliation(s)
- V W Chan
- George Williams Hooper Foundation, University of California, San Francisco 94143, USA
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28
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Ordentlich P, Lin A, Shen CP, Blaumueller C, Matsuno K, Artavanis-Tsakonas S, Kadesch T. Notch inhibition of E47 supports the existence of a novel signaling pathway. Mol Cell Biol 1998; 18:2230-9. [PMID: 9528794 PMCID: PMC121468 DOI: 10.1128/mcb.18.4.2230] [Citation(s) in RCA: 208] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/1997] [Accepted: 01/03/1998] [Indexed: 02/07/2023] Open
Abstract
E47 is a widely expressed transcription factor that activates B-cell-specific immunoglobulin gene transcription and is required for early B-cell development. In an effort to identify processes that regulate E47, and potentially B-cell development, we found that activated Notch1 and Notch2 effectively inhibit E47 activity. Only the intact E47 protein was inhibited by Notch-fusion proteins containing isolated DNA binding and activation domains were unaffected-suggesting that Notch targets an atypical E47 cofactor. Although overexpression of the coactivator p300 partially reversed E47 inhibition, results of several assays indicated that p300/CBP is not a general target of Notch. Notch inhibition of E47 did not correlate with its ability to activate CBF1/RBP-Jkappa, the mammalian homolog of Suppressor of Hairless, a protein that associates physically with Notch and defines the only known Notch signaling pathway in drosophila. Importantly, E47 was inhibited independently of CBF1/RPB-Jkappa by Deltex, a second Notch-interacting protein. We provide evidence that Notch and Deltex may act on E47 by inhibiting signaling through Ras because (i) full E47 activity was found to be dependent on Ras and (ii) both Notch and Deltex inhibited GAL4-Jun, a hybrid transcription factor whose activity is dependent on signaling from Ras to SAPK/JNK.
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Affiliation(s)
- P Ordentlich
- Howard Hughes Medical Institute and Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia 19104-6145, USA
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29
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Deehan MR, Frame MJ, Parkhouse RME, Seatter SD, Reid SD, Harnett MM, Harnett W. A Phosphorylcholine-Containing Filarial Nematode-Secreted Product Disrupts B Lymphocyte Activation by Targeting Key Proliferative Signaling Pathways. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.6.2692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Filarial nematodes infect more than 100 million people in the tropics, causing elephantiasis, chronic skin lesions, and blindness. The parasites are long-lived as a consequence of being able to evade the host immune system, but an understanding of the molecular mechanisms underlying this evasion remains elusive. In this study, we demonstrate that ES-62 (2 μg/ml), a phosphorylcholine (PC)-containing glycoprotein released by the rodent filarial parasite Acanthocheilonema viteae, is able to polyclonally activate certain protein tyrosine kinase and mitogen-activating protein kinase signal-transduction elements in B lymphocytes. Although this interaction is insufficient to cause B lymphocyte proliferation per se, it serves to desensitize the cells to subsequent activation of the phosphoinositide-3-kinase and Ras mitogen-activating protein kinase pathways, and hence also to proliferation, via the Ag receptor. The active component of ES-62 appears to be PC, a molecule recently shown to act as an intracellular signal transducer, as the results obtained with ES-62 are broadly mimicked by PC alone. As PC-containing secreted products (PC-ES) are also released by human filarial parasites, our data suggest that PC-ES, by interfering with B cell function, could play a role in prolonging filarial infection in parasitized individuals.
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Affiliation(s)
- Maureen R. Deehan
- *Department of Immunology, University of Strathclyde, Glasgow, United Kingdom
| | - Mhairi J. Frame
- *Department of Immunology, University of Strathclyde, Glasgow, United Kingdom
| | | | - Sandra D. Seatter
- ‡Department of Immunology, University of Glasgow, Glasgow, United Kingdom
| | - Steven D. Reid
- ‡Department of Immunology, University of Glasgow, Glasgow, United Kingdom
| | | | - William Harnett
- *Department of Immunology, University of Strathclyde, Glasgow, United Kingdom
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30
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Miyazaki T. Two distinct steps during thymocyte maturation from CD4-CD8- to CD4+CD8+ distinguished in the early growth response (Egr)-1 transgenic mice with a recombinase-activating gene-deficient background. J Exp Med 1997; 186:877-85. [PMID: 9294142 PMCID: PMC2199048 DOI: 10.1084/jem.186.6.877] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The early growth response (Egr)-1 is a zinc finger-containing transcription factor belonging to the immediate-early genes. Its expression in CD4/CD8 double negative (DN) immature thymocytes suggests that Egr-1 expression may be involved in early thymocyte development. In transgenic mice overexpressing Egr-1 in a recombinase-activating gene-deficient background, thymocytes bypassed the block at the CD25+CD44- DN stage and matured to the immature CD8 single-positive (ISP) cell stage, but not further to the CD4/CD8 double-positive (DP) cell stage. When these mice were irradiated, thymocytes did develop to the DP stage, suggesting transcriptional induction of additional genes by irradiation that are required to promote thymocyte development from the ISP to the DP stage. These results provide genetic evidence for two distinct steps during early thymocyte development from the CD25+CD44- DN to the DP stage. The first step, from the CD25+CD44- DN to the ISP stage, can be entirely promoted by overexpression of Egr-1.
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Affiliation(s)
- T Miyazaki
- Basel Institute for Immunology, Postfach CH-4005, Basel, Switzerland.
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31
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Harmer SL, DeFranco AL. Shc contains two Grb2 binding sites needed for efficient formation of complexes with SOS in B lymphocytes. Mol Cell Biol 1997; 17:4087-95. [PMID: 9199344 PMCID: PMC232262 DOI: 10.1128/mcb.17.7.4087] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Cross-linking of the B-cell antigen receptor (BCR) induces tyrosine phosphorylation of Shc, which is believed to lead to the activation of Ras. Previous work has shown that tyrosine-phosphorylated Shc forms complexes with another adapter protein, Grb2, and the Ras guanine nucleotide exchange factor SOS. Here, we demonstrate that phosphorylation of Shc by the hematopoietic cell-specific tyrosine kinase Syk induces binding of Grb2 to Shc, suggesting that Syk phosphorylates Shc in stimulated B cells. Surprisingly, Syk-phosphorylated Shc possesses two Grb2 binding sites rather than the one site that has been previously reported. Both of these sites are required for efficient formation of Shc-Grb2-SOS complexes in vitro and in vivo. We suggest that two Grb2 proteins anchored by a single Shc protein bind simultaneously to one SOS molecule, resulting in a complex that is more stable than a complex containing only a single Grb2 protein bound to one SOS molecule. This model is consistent with our observation that BCR stimulation greatly increases the amount of SOS associated with Grb2.
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Affiliation(s)
- S L Harmer
- G.W. Hooper Foundation and Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0552, USA
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32
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Abstract
Cross-linking of the B cell antigen receptor (BCR) leads to the activation of three types of intracellular protein tyrosine kinases. These tyrosine kinases then phosphorylate signaling components to activate a variety of signaling reactions, including phosphatidylinositol 4,5-bisphosphate hydrolysis, Ras activation, and phosphatidylinositol 3-kinase activation. Each of these signaling reactions, and also the signaling molecules Vav and HS1, appears to be important for at least some of the many types of B cell responses to antigen. The complexity of BCR signaling reactions may be required to allow the B cell to respond in a number of distinct ways to antigen (proliferation, survival, apoptosis, maturational arrest, etc.) depending on the maturation state of the B cell, the location in the body, the physical nature of the antigen, and the possible presence of the antigen in complex with antibody or complement components.
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Affiliation(s)
- A L DeFranco
- George Williams Hooper Foundation, Department of Microbiology, University of California, San Francisco, CA 94143-0552, USA.
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33
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Healy JI, Dolmetsch RE, Timmerman LA, Cyster JG, Thomas ML, Crabtree GR, Lewis RS, Goodnow CC. Different nuclear signals are activated by the B cell receptor during positive versus negative signaling. Immunity 1997; 6:419-28. [PMID: 9133421 DOI: 10.1016/s1074-7613(00)80285-x] [Citation(s) in RCA: 320] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It is not known how immunogenic versus tolerogenic cellular responses are signaled by receptors such as the B cell antigen receptor (BCR). Here we compare BCR signaling in naive cells that respond positively to foreign antigen and self-tolerant cells that respond negatively to self-antigen. In naive cells, foreign antigen triggered a large biphasic calcium response and activated nuclear signals through NF-AT, NF-kappa B, JNK, and ERK/pp90rsk. In tolerant B cells, self-antigen stimulated low calcium oscillations and activated NF-AT and ERK/pp90rsk but not NF-kappa B or JNK. Self-reactive B cells lacking the phosphatase CD45 did not exhibit calcium oscillations or ERK/pp90rsk activation, nor did they repond negatively to self-antigen. These data reveal striking biochemical differences in BCR signaling to the nucleus during positive selection by foreign antigens and negative selection by self-antigens.
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Affiliation(s)
- J I Healy
- Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305, USA
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34
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Li X, Franklin CC, Kraft AS, Carter RH. Ligation of membrane IgM stimulates a novel c-Jun amino-terminal domain kinase activity in Daudi human B cells. Mol Immunol 1997; 34:409-18. [PMID: 9293774 DOI: 10.1016/s0161-5890(97)00035-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Stress-activated protein kinases (SAPK; also known as JNK for c-Jun N-terminal kinase) phosphorylate Ser63 and Ser73 in the amino-terminus of the c-Jun protein and potentiate its transcriptional activity. We have analysed phosphorylation of GST fusion proteins containing the c-Jun N-terminal domain by lysates of Daudi human B lymphoblastoid cells stimulated with medium or anti-IgM. Crosslinking membrane IgM (mIgM) results in an increase in phosphorylation of GST-c-Jun (5-89) in an antibody dose-dependent manner. The kinase activity specifically phosphorylates the c-Jun N-terminal domain since it does not phosphorylate GST or GST-JunB. The activity preferentially phosphorylates the substrate that contains the sites for in vivo phosphorylation by SAPK/JNK and requires the delta domain of c-Jun, which is also required for SAPK/JNK activity. However, the c-Jun N-terminal kinase activity induced by mIgM ligation is not precipitatable with anti-SAPK/JNK antibodies. In addition, unlike SAPK/JNKs, the mIgM-dependent c-Jun N-terminal kinase activity is not detectable in assays for renaturable kinase activity (in-gel assay) or in assays that test activities that bind to c-Jun (solid-phase assay). The increased phosphorylation of c-Jun N-terminal domain in response to mIgM ligation is unlikely to be due to mIgM-activated ERKs as it was not suppressed by a selective MEK inhibitor. Thus, the mIgM-induced activity is distinct from the known SAPK/JNKs and may represent a novel mechanism for c-Jun phosphorylation in response to mIgM engagement in human B cells.
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Affiliation(s)
- X Li
- Department of Medicine, University of Alabama at Birmingham 35294, U.S.A
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35
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Rupprecht HD, Hoffer G, de Heer E, Sterzel RB, Faller G, Schoecklmann HO. Expression of the transcriptional regulator Egr-1 in experimental glomerulonephritis: requirement for mesangial cell proliferation. Kidney Int 1997; 51:694-702. [PMID: 9067901 DOI: 10.1038/ki.1997.100] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The early growth response gene-1 (Egr-1), a zinc finger transcriptional regulator, was induced in a rat model of mesangioproliferative glomerulonephritis (GN). Northern blot analysis revealed a maximal 14.9-fold increase in glomerular Egr-1 mRNA at day 6 of GN. By immunohistochemistry Egr-1 protein expression was demonstrated to be mainly confined to glomerular mesangial cells (MC). To test whether Egr-1 directly regulates MC proliferation, cultured MCs were stimulated with platelet-derived growth factor (PDGF) after preincubation with different Egr-1 antisense oligonucleotides (ASOs). PDGF-induced rise in 3H-thymidine uptake by 83% and almost completely abrogated increase in MC number. We conclude that Egr-1 induction is of critical importance for PDGF-induced mitogenic signaling in MCs, and inhibition of Egr-1 in vivo may offer an approach to oppose glomerular MC proliferation in glomerular inflammatory disease.
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Affiliation(s)
- H D Rupprecht
- Medizinische Klinik IV, Institut der Universität Erlangen-Nümberg, Erlangen, Germany
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36
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Shao H, Kono DH, Chen LY, Rubin EM, Kaye J. Induction of the early growth response (Egr) family of transcription factors during thymic selection. J Exp Med 1997; 185:731-44. [PMID: 9034151 PMCID: PMC2196139 DOI: 10.1084/jem.185.4.731] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/1996] [Revised: 12/09/1996] [Indexed: 02/03/2023] Open
Abstract
There is little known about the regulation of gene expression during TCR-mediated differentiation of immature CD4+8+ (double positive) thymocytes into mature T cells. Using the DPK CD4+8+ thymocyte precursor cell line, we demonstrate that the early growth response-1 gene (Erg-1), encoding a zinc finger transcription factor, is rapidly upregulated after TCR stimulation. We also report that Egr-1 is expressed by a subset of normal double positive thymocytes in the thymic cortex, as well by a majority of medullary single positive thymocytes. Expression of Egr-1 is dramatically reduced in the thymus of major histocompatibility complex knockout mice, but can be induced by anti-CD3 antibody stimulation of isolated thymocytes from these animals. These and other data suggest that high level expression of Egr-1 in the thymus is a consequence of selection. A similar pattern of expression is found for family members Egr-2 and Egr-3. Using the DPK cell line, we also demonstrate that expression of Egr-1, 2, and 3 is dependent upon ras activation, as is the initiation of differentiation to a single positive cell. In contrast, the calcineurin inhibitor cyclosporin A, which inhibits DPK cell differentiation as well as positive selection, inhibits expression of Egr-2 and Egr-3, but not Egr-1. The identification of the Egr family in this context represents the first report of a link between the two known signaling pathways involved in positive selection and downstream transcriptional regulators.
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Affiliation(s)
- H Shao
- Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA
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37
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Abstract
Fc gamma receptors type IIb1 (Fc gammaRIIb1) inhibit B-cell activation when co-ligated with B-cell antigen receptors (BCR) by immune complexes. In murine B-cells the inhibition is mediated by the interaction of the phosphorylated immunoreceptor tyrosine-based inhibitory motif (P-ITIM) of Fc gammaRIIb1 with the SH2 domain containing protein tyrosine phosphatase. SHP1. To clarify the mechanism of Fc gammaRIIb mediated inhibition of human B-cells we have studied the association of signaling molecules with human Fc gammaRIIb1 after co-ligating with BCR. Fc gammaRIIb1 were affinity purified from the Burkitt lymphoma cell line, BL41. Several tyrosine phosphorylated proteins were co-isolated with Fc gammaRIIb1 at 145, 110, and 50 60 kDa, which were not present in Fc gammaRIIb1 free immune complexes. Among these molecules we have identified the p52 Shc adaptor protein. Furthermore, we have shown that the insolubilised synthetic peptide corresponding P-ITIM bound Shc, Lyn and the p75 and p 10 unidentified tyrosine phosphorylated proteins. Here we describe that the cell membrane associated Shc is partially dephosphorylated in BCR-Fc gammaRIIb1 co-ligated samples, suggesting that its function in regulating p21ras monomeric G protein is impaired. Indeed, we have detected a lower p21ras activity in BCR-Fc gammaRIIb1 co-crosslinked samples. These data indicate that co-ligation of BCR and Fc gammaRIIb1 interrupts signal transduction between protein tyrosine kinase activation and p21ras mediated activation pathway. Since in contrast to the mouse B-cells both Fc gammaRIIb1 and Fc gammaRIIb2 are expressed in human B-cells, we have investigated the inhibitory function of the two receptors in Fc gammaRIIb negative Burkitt lymphoma cell line ST486 transfected with Fc gammaRIIb1 and Fc gammaRIIb2, respectively. Both Fc gammaRIIb1 and Fc gammaRIIb2 inhibited the rise of intracellular Ca2+ induced by the crosslinking of BCR. The rate of the inhibition depended on the ratio of the co-crosslinked receptors (BCR-Fc gammaRIIb1) to the crosslinked BCR (BCR-BCR). Co-crosslinking of the two receptors inhibited not only the capacitive Ca2+ entry but rather the total Ca2+ response in both Fc gammaRIIb1 and Fc gammaRIIb2 transfected human B-cells. CD19 represents the signal transduction unit of complement receptor, CR2 (CD21), and is responsible for the complement activating IgM-immune complex induced enhancement of B-cell activation. Co-crosslinking of CD19 and BCR was shown to enhance B-cell activation due to the recruitment of further signaling molecules to the activator complex by the phosphorylated tyrosine residues of CD19. Here we show a novel finding that co-ligation of CD19 with Fc gammaRIIb1 inhibits the CD19-induced upregulation of Ca2+ response. The results indicate that IgG plus complement containing immune complexes may inhibit B-cell activation in vivo, due to the Fc gammaRIIb1-mediated interruption of signal transduction via both BCR and CD19.
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Affiliation(s)
- G Sármay
- Lorand Eotvos University, Department of Immunology, God, Hungary
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38
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Sármay G, Koncz G, Gergely J. Human type II Fcgamma receptors inhibit B cell activation by interacting with the p21(ras)-dependent pathway. J Biol Chem 1996; 271:30499-504. [PMID: 8940017 DOI: 10.1074/jbc.271.48.30499] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Co-ligation of antigen receptors and type II Fcgamma receptors (FcgammaRIIb) on B cells interrupts signal transduction and ultimately inhibits antibody production. We have identified p52 Shc in the FcgammaRIIb1-specific immunoprecipitates isolated from the membrane fraction of BL41 Burkitt lymphoma cells following B cell receptor-FcgammaRIIb1 co-ligation. The insolubilized synthetic peptide representing the phosphorylated form of the tyrosine-based inhibitory motif of FcgammaRIIb also binds Shc from the lysates of activated but not from resting BL41 cells. This suggests that the binding does not depend on the interaction of FcgammaRIIb1-phosphotyrosine with the SH2 domain of Shc. Tyr phosphorylation of FcgammaRIIb1-associated Shc is low, indicating an impaired function. Shc is implicated in regulating p21(ras) activation; thus, we have compared p21(ras) activities in BL41 cells treated in different ways. p21(ras) activity is reduced when B cell receptor and FcgammaRIIb1 are co-ligated. p21(ras) couples protein-tyrosine kinase-dependent events to the Ser/Thr kinase-mediated signaling pathway leading to the activation of mitogen-activated protein kinases (MAPK). Our results show that B cell receptor-FcgammaRIIb1 co-cross-linking partially inhibits mitogen-activated protein kinase activity. We conclude that FcgammaRIIb1-dependent inhibition of human B cell activation may be based on interrupting signal transduction between protein-tyrosine kinases and the p21(ras)/mitogen-activated protein kinase-dependent activation pathway.
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Affiliation(s)
- G Sármay
- Laboratory of Immunoregulation, Vienna International Research Cooperation Center at SFI, Vienna, Austria
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39
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Poinot-Chazel C, Portier M, Bouaboula M, Vita N, Pecceu F, Gully D, Monroe JG, Maffrand JP, Le Fur G, Casellas P. Activation of mitogen-activated protein kinase couples neurotensin receptor stimulation to induction of the primary response gene Krox-24. Biochem J 1996; 320 ( Pt 1):145-51. [PMID: 8947479 PMCID: PMC1217909 DOI: 10.1042/bj3200145] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Neurotensin (NT) is a neuropeptide that is important in a variety of biological processes such as signal transduction and cell growth. NT effects are mediated by a single class of cell-surface receptors, known as neurotensin receptors (NTRs), which exhibit structural features of the G-protein-coupled receptors superfamily. We investigated NTR signalling properties with Chinese hamster ovary (CHO) cells stably transformed with human NTR (hNTR). First, we showed that NTR stimulation by NT induced the activation of the mitogen-activated protein kinases (MAPKs) in time- and dose-dependent manners. Both p42 and p44 MAPK isoforms were retarded in gel-shift assays, which was consistent with their activation by phosphorylation. In addition we showed that NT caused a prolonged activation of MAPK as measured by in-gel kinase assay. Secondly, we demonstrated that NT induced the expression of the growth-related gene Krox-24 at the protein level, as assessed by Western-blot analysis, and at the transcriptional level, as demonstrated in CHO cells transfected with hNTR and a reporter gene for Krox-24. Activation of MAPK and induction of Krox-24 were both prevented by the NTR antagonist SR 48692, confirming the specific action on NTR. Furthermore we observed coupling of NTR to a mitogenic pathway and Krox-24 induction in the human adenocarcinoma cell line HT29, which naturally expresses NTRs. Considering coupling pathways between NTR stimulation and MAPK activation, we observed a partial inhibition by pertussis toxin (PTX) and a complete blockade by the protein kinase C (PKC) inhibitor GF 109203X. Taken together, these results suggest that (1) stimulation of NTR activates the MAPK pathway by mechanisms involving dual coupling to both PTX-sensitive and PTX-insensitive G-proteins as well as PKC activation, and (2) these effects are associated with the induction of Krox-24, which might be a target of MAPK effector.
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40
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Bouaboula M, Poinot-Chazel C, Marchand J, Canat X, Bourrié B, Rinaldi-Carmona M, Calandra B, Le Fur G, Casellas P. Signaling pathway associated with stimulation of CB2 peripheral cannabinoid receptor. Involvement of both mitogen-activated protein kinase and induction of Krox-24 expression. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 237:704-11. [PMID: 8647116 DOI: 10.1111/j.1432-1033.1996.0704p.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cannabinoids, known for their psychoactive effects, also possess immunomodulatory properties. The recent isolation and cloning of the G-protein-coupled peripheral cannabinoid receptor (CB2), mainly expressed in immune tissues, have provided molecular tools to determine how cannabinoid compounds may mediate immunomodulation. We here investigated the CB2 signaling properties using stably transfected Chinese hamster ovary cells expressing human CB2. First, we showed that stimulation by a cannabinoid agonist activated mitogen-activated protein (MAP) kinase in time- and dose-dependent manners. The rank order of potency for MAP kinase activation of cannabinoid agonists correlated well with their binding capacities. Second, we demonstrated that, following MAP kinase activation, cannabinoids induced the expression of the growth-related gene Krox-24, also known as NGFI-A, zif/268, and egr-1. Pertussis toxin completely prevented both MAP kinase activation and Krox-24 induction, even more these responses appeared to be dependent of specific protein kinase C isoforms and independent of inhibition of adenylyl cyclase. A similar coupling of CB2 to a mitogenic pathway and to the regulation of Krox-24 expression was also observed in human promyelocytic cells HL60. Taken together, these findings provide evidence for a functional role of the CB2 receptor in gene induction mediated by the MAP kinase network.
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Affiliation(s)
- M Bouaboula
- Sanofi Recherche, Department of Immunopharmacology, Montpellier, France
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41
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Maltzman JS, Carman JA, Monroe JG. Role of EGR1 in regulation of stimulus-dependent CD44 transcription in B lymphocytes. Mol Cell Biol 1996; 16:2283-94. [PMID: 8628295 PMCID: PMC231216 DOI: 10.1128/mcb.16.5.2283] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The immediate-early gene egr-1 encodes a transcription factor (EGR1) that links B-cell antigen receptor (BCR) signals to downstream activation events through the regulation of previously unidentified target genes. Here we identify the gene encoding the lymphocyte homing and migration protein CD44 as a target of EGR1 regulation in B cells. BCR-induced increases in CD44 mRNA expression and transcription levels are shown to occur in EGR1-expressing but not in nonexpressing subclones of the B-cell line WEHI-231. Kinetics of egr-1 transcription and the appearance of nuclear EGR1 protein precede CD44 induction and occur within 30 min after stimulation in the EGR1-expressing subclone. A single EGR1 binding motif is demonstrated at bp -301 of the human CD44 promoter. Cotransfection of a CD44 promoter-chloramphenicol acetyltransferase reporter construct with an egr-1 expression vector resulted in a 6.5- to 8.5-fold induction of transcriptional activity relative to an empty expression vector. The EGR1 binding motif was shown to be necessary for stimulus-induced expression of a CD44 promoter-chloramphenicol acetyltransferase reporter construct in nontransformed B lymphocytes and was required for transactivation by an EGR1 expression vector in a B-cell line. These studies identify EGR1 as an intermediary linking BCR-derived signals to the induction of CD44. The relevance of these molecular events to BCR signal transduction and antigen-stimulated B-cell-mediated immune responses is discussed.
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Affiliation(s)
- J S Maltzman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, School of Medicine, Philadelphia, 19104, USA
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42
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Maltzman JS, Carmen JA, Monroe JG. Transcriptional regulation of the Icam-1 gene in antigen receptor- and phorbol ester-stimulated B lymphocytes: role for transcription factor EGR1. J Exp Med 1996; 183:1747-59. [PMID: 8666932 PMCID: PMC2192508 DOI: 10.1084/jem.183.4.1747] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Intercellular adhesion molecule (ICAM) 1/CD54 plays an important role in T cell dependent B cell activation and for function of B lymphocytes as antigen-presenting cells. ICAM-1 expression is upregulated as a consequence of B lymphocyte antigen receptor (BCR) signaling, thereby serving to render antigen-stimulated B cells more receptive to T cell-mediated costimulatory signals. We have investigated BCR-induced expression of the Icam-1 gene in primary B cells and B cell lines and have found it to be dependent on BCR-induced expression of the transcription factor EGR1. Icam-1 transcription, induced by BCR cross-linking or bypassing the BCR with phorbol ester, is absent in a B cell line in which the EGR1-encoding gene (egr-1) is methylated and not expressed. A potential EGR1-binding site was located at -701 bp upstream of the murine Icam-1 gene transcription start site and shown by electrophoretic mobility shift assay to bind to murine EGR1. Mutation of this site in the context of 1.1 kb of the Icam-1 promoter significantly abrogated transcriptional induction by phorbol ester and anti-mu stimulation in primary B cells. A direct effect of EGR1 on the Icam-1 promoter is suggested by the ability of EGR1 expressed from an SV40-driven expression vector transactivate the wild-type Icam-1 promoter, whereas mutation of the EGR1 mutation of the EGR1 binding motif at -701 bp markedly compromises this induction. These data identify EGR1 as a signaling intermediate in BCR-stimulated B cell functional responses, specifically linking BCR signal transduction to induction of the Icam-1 gene. Furthermore, similar findings for BCR-induced CD44 gene induction (Maltzman, J.S., J.A. Carman, and J.G. Monroe. 1996. Role of EGR1 in regulation of stimulus-dependent CD44 transcription in B lymphocytes. Mol. Cell. Biol. In press) suggest that EGR1 may be an important signaling molecule for regulating levels of migration and adhesion molecules during humoral immune responses.
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Affiliation(s)
- J S Maltzman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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43
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Perlmutter RM, Alberola-Ila J. The use of dominant-negative mutations to elucidate signal transduction pathways in lymphocytes. Curr Opin Immunol 1996; 8:285-90. [PMID: 8725953 DOI: 10.1016/s0952-7915(96)80069-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Recent publications document an exponential increase in the use of dominant-negative mutations as tools for the experimental dissection of lymphocyte signaling pathways. This approach may be the only one available for in vitro analysis of cell lines. Moreover, when implemented in transgenic animals, dominant-negative mutations boast certain advantages over gene-targeting strategies.
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Affiliation(s)
- R M Perlmutter
- Howard Hughes Medical Institute, Department of Immunology, University of Washington, Seattle 98195, USA.
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44
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Bouaboula M, Poinot-Chazel C, Bourrié B, Canat X, Calandra B, Rinaldi-Carmona M, Le Fur G, Casellas P. Activation of mitogen-activated protein kinases by stimulation of the central cannabinoid receptor CB1. Biochem J 1995; 312 ( Pt 2):637-41. [PMID: 8526880 PMCID: PMC1136308 DOI: 10.1042/bj3120637] [Citation(s) in RCA: 372] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The G-protein-coupled central cannabinoid receptor (CB1) has been shown to be functionally associated with several biological responses including inhibition of adenylate cyclase, modulation of ion channels and induction of the immediate-early gene Krox-24. Using stably transfected Chinese Hamster Ovary cells expressing human CB1 we show here that cannabinoid treatment induces both phosphorylation and activation of mitogen-activated protein (MAP) kinases, and that these effects are inhibited by SR 141716A, a selective CB1 antagonist. The two p42 and p44 kDa MAP kinases are activated in a time- and dose-dependent manner. The rank order of potency for the activation of MAP kinases with various cannabinoid agonists is CP-55940 > delta 9-tetrahydrocannabinol > WIN 55212.2, in agreement with the pharmacological profile of CB1. The activation of MAP kinases is blocked by pertussis toxin but not by treatment with hydrolysis-resistant cyclic AMP analogues. This suggests that the signal transduction pathway between CB1 and MAP kinases involves a pertussis-toxin-sensitive GTP-binding protein and is independent of cyclic AMP metabolism. This coupling of CB1 subtype and mitogenic signal pathway, also observed in the human astrocytoma cell line U373 MG, may explain the mechanism of action underlying cannabinoid-induced Krox-24 induction.
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Affiliation(s)
- M Bouaboula
- Sanofi Recherche, Department of Immunopharmacology, Montpellier, France
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45
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Holder EL, Al Moustafa AE, Chalifour LE. Molecular remodelling in hypertrophied hearts from polyomavirus large T-antigen transgenic mice. Mol Cell Biochem 1995; 152:131-41. [PMID: 8751159 DOI: 10.1007/bf01076075] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Polyomavirus large T-antigen transgenic mice develop cardiac hypertrophy characterized by an increase in atrial natriuretic factor and beta-myosin heavy chain isoform expression. The aim of this study was to examine changes in proto-oncogene expression in hypertrophied hearts from the transgenic mice. Expression of early growth response-1 (Egr-1) mRNA was detected in hearts from all 15 transgenic mice, but was not detectable in 13 control mice. Reverse transcriptase-polymerase chain reaction experiments using Egr-1-specific primers confirmed the increase in Egr-1 mRNA in enlarged hearts from the transgenic mice. Expression of c-jun, junD and Ha-ras mRNAs was increased in the transgenic hearts 3, 17 and 2.8-fold respectively. Western blots showed an increase in c-myc, c-jun and ras protein in hypertrophied transgenic hearts. Immunofluorescence analyses confirmed an increase in Egr-1 and c-jun protein in transgenic cardiomyocytes. Proliferating cell nuclear antigen, Ki-ras and HSP 90 mRNAs were decreased 22, 2.7 and 3-fold, respectively in the transgenic hearts. Not altered in most hypertrophied hearts was expression of c-fos, junB, p53, c-neu, c-myc, HSP70, HSP27, TGF-beta or IGF 1 mRNAs. Proto-oncogene and growth factor gene expression in hypertrophy induced by PVLT expression is modulated with some proto-oncogenes increased and others decreased in expression.
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Affiliation(s)
- E L Holder
- Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montréal, Québe
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46
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López-Cabrera M, Muñoz E, Blázquez MV, Ursa MA, Santis AG, Sánchez-Madrid F. Transcriptional regulation of the gene encoding the human C-type lectin leukocyte receptor AIM/CD69 and functional characterization of its tumor necrosis factor-alpha-responsive elements. J Biol Chem 1995; 270:21545-51. [PMID: 7665567 DOI: 10.1074/jbc.270.37.21545] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The human activation antigen CD69 is a member of the C-type animal lectin superfamily that functions as a signal-transmitting receptor. Although the expression of CD69 can be induced in vitro on cells of most hematopoietic lineages with a wide variety of stimuli, in vivo it is mainly expressed by T-lymphocytes located in the inflammatory infiltrates of several human diseases. To elucidate the mechanisms that regulate the constitutive and inducible expression of CD69 by leukocytes, we isolated the promoter region of the CD69 gene and carried out its functional characterization. Sequence analysis of the 5'-flanking region of the CD69 gene revealed the presence of a potential TATA element 30 base pairs upstream of the major transcription initiation site and several putative binding sequences for inducible transcription factors (NF-kappa B, Egr-1, AP-1), which might mediate the inducible expression of this gene. Transient expression of CD69 promoter-based reporter gene constructs in K562 cells indicated that the proximal promoter region spanning positions -78 to +16 contained the cis-acting sequences necessary for basal and phorbol 12-myristate 13-acetate-inducible transcription of the CD69 gene. Removal of the upstream sequences located between positions -78 and -38 resulted in decreased promoter strength and abolished the response to phorbol 12-myristate 13-acetate. We also found that tumor necrosis factor-alpha (TNF-alpha) is capable of inducing the surface expression of the CD69 molecule as well as the promoter activity of fusion plasmids that contain 5'-flanking sequences of the CD69 gene, suggesting that this cytokine may regulate in vivo the expression of CD69.(ABSTRACT TRUNCATED AT 250 WORDS)
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MESH Headings
- Amino Acid Sequence
- Antigens, CD/biosynthesis
- Antigens, CD/genetics
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/genetics
- Base Composition
- Base Sequence
- Binding Sites
- Cell Line
- Chromosomes, Human, Pair 12
- DNA/chemistry
- DNA/drug effects
- DNA/metabolism
- DNA-Binding Proteins/metabolism
- Early Growth Response Protein 1
- Gene Expression Regulation
- Gene Library
- Humans
- Immediate-Early Proteins
- Lectins, C-Type
- Molecular Sequence Data
- NF-kappa B/metabolism
- Oligodeoxyribonucleotides
- Promoter Regions, Genetic
- Restriction Mapping
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- TATA Box
- Transcription Factor AP-1/metabolism
- Transcription Factors/metabolism
- Transcription, Genetic
- Tumor Cells, Cultured
- Tumor Necrosis Factor-alpha/pharmacology
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Affiliation(s)
- M López-Cabrera
- Unidad de Biología Molecular, Hospital de la Princesa, Universidad Autónoma de Madrid, Spain
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47
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McMahon SB, Norvell A, Levine KJ, Monroe JG. Transient transfection of murine B lymphocyte blasts as a method for examining gene regulation in primary B cells. J Immunol Methods 1995; 179:251-9. [PMID: 7876572 DOI: 10.1016/0022-1759(94)00292-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Studies of the biochemical and genetic processes associated with activation of B lymphocytes have contributed much to the understanding of the regulation of the B cell response to antigen. Primary, non-transformed B cells from the spleen in mice and the tonsils or peripheral blood in humans have proven to be informative models for dissection of the biochemical events leading to B cell activation. In contrast, genetic studies of this process have relied on transformed cell lines grown in culture. The influence of the transformed state on the results obtained using these models may limit their physiological relevance. This report describes a method whereby non-transformed B lymphocytes in primary culture can be transfected for use in studies of gene regulation in response to antigen receptor signals. Transfection was accomplished after only a 72 h exposure to LPS. The cells obtained after LPS treatment were greater than 97% pure, and more importantly, remained responsive to antigen-receptor generated signals. Responsiveness was confirmed by demonstrating induction of mRNA for the primary response gene egr-1, as well as induction of specific transcription factor binding activity in nuclear extracts from these cells. DEAE-dextran-mediated transient transfection was utilized to introduce an egr-1 promoter/reporter construct into these cells. This analysis of promoter activity yielded results which were indistinguishable from the pattern of expression of the endogenous egr-1 gene. Potential applications for dissection of transcriptional regulatory pathways in B lymphocytes are discussed.
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Affiliation(s)
- S B McMahon
- Department of Pathology and Laboratory Medicine, School of Medicine, University of Pennsylvania, Philadelphia 19104
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Ishiguro N, Izawa H, Shinagawa M, Shimamoto T, Tsuchiya T. Cloning and nucleotide sequence of the gene (citC) encoding a citrate carrier from several Salmonella serovars. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50127-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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