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Loss of Gα i proteins impairs thymocyte development, disrupts T-cell trafficking, and leads to an expanded population of splenic CD4 +PD-1 +CXCR5 +/- T-cells. Sci Rep 2017. [PMID: 28646160 PMCID: PMC5482867 DOI: 10.1038/s41598-017-04537-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Thymocyte and T cell trafficking relies on signals initiated by G-protein coupled receptors. To address the importance of the G-proteins Gαi2 and Gαi3 in thymocyte and T cell function, we developed several mouse models. Gαi2 deficiency in hematopoietic progenitors led to a small thymus, a double negative (DN)1/DN2 thymocyte transition block, and an accumulation of mature single positive (SP) thymocytes. Loss at the double positive (DP) stage of thymocyte development caused an increase in mature cells within the thymus. In both models an abnormal distribution of memory and naïve CD4 T cells occurred, and peripheral CD4 and CD8 T cells had reduced chemoattractant responses. The loss of Gαi3 had no discernable impact, however the lack of both G-proteins commencing at the DP stage caused a severe T cell phenotype. These mice lacked a thymic medullary region, exhibited thymocyte retention, had a peripheral T cell deficiency, and lacked T cell chemoattractant responses. Yet a noteworthy population of CD4+PD-1+CXCR5+/− cells resided in the spleen of these mice likely due to a loss of regulatory T cell function. Our results delineate a role for Gαi2 in early thymocyte development and for Gαi2/3 in multiple aspects of T cell biology.
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2
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Hwang IY, Park C, Harrison K, Kehrl JH. Normal Thymocyte Egress, T Cell Trafficking, and CD4 + T Cell Homeostasis Require Interactions between RGS Proteins and Gα i2. THE JOURNAL OF IMMUNOLOGY 2017; 198:2721-2734. [PMID: 28235863 DOI: 10.4049/jimmunol.1601433] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 01/24/2017] [Indexed: 11/19/2022]
Abstract
Adaptive immunity depends on mature thymocytes leaving the thymus to enter the bloodstream and the trafficking of T cells through lymphoid organs. Both of these require heterotrimeric Gαi protein signaling, whose intensity and duration are controlled by the regulator of G protein signaling (RGS) proteins. In this study, we show that RGS protein/Gαi2 interactions are essential for normal thymocyte egress, T cell trafficking, and homeostasis. Mature thymocytes with a Gαi2 mutation that disables RGS protein binding accumulated in the perivascular channels of thymic corticomedullary venules. Severe reductions in peripheral naive CD4+ T cells and regulatory T cells occurred. The mutant CD4+ T cells adhered poorly to high endothelial venules and exhibited defects in lymph node entrance and egress. The kinetics of chemokine receptor signaling were disturbed, including chemokine- induced integrin activation. Despite the thymic and lymph node egress defects, sphingosine-1-phosphate signaling was not obviously perturbed. This study reveals how RGS proteins modulate Gαi2 signaling to facilitate thymocyte egress and T cell trafficking.
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Affiliation(s)
- Il-Young Hwang
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Chung Park
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Kathleen Harrison
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - John H Kehrl
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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3
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Valatas V, Bamias G, Kolios G. Experimental colitis models: Insights into the pathogenesis of inflammatory bowel disease and translational issues. Eur J Pharmacol 2015; 759:253-64. [DOI: 10.1016/j.ejphar.2015.03.017] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 02/03/2015] [Accepted: 03/12/2015] [Indexed: 02/06/2023]
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4
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Sethakorn N, Dulin NO. RGS expression in cancer: oncomining the cancer microarray data. J Recept Signal Transduct Res 2013; 33:166-71. [DOI: 10.3109/10799893.2013.773450] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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5
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Peña JA, Thompson-Snipes L, Calkins PR, Tatevian N, Puppi M, Finegold MJ. Alterations in myeloid dendritic cell innate immune responses in the Galphai2-deficient mouse model of colitis. Inflamm Bowel Dis 2009; 15:248-60. [PMID: 19037851 PMCID: PMC2627792 DOI: 10.1002/ibd.20744] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND The G protein alpha subunit type-2 (Galpha(i)2)-deficient mouse develops inflammatory bowel disease (IBD) with increased severity in mice on a 129SvEv (129) background compared to the C57BL/6 (B6) background. Since dendritic cells (DCs) are key cells of innate immunity, we determined whether Galpha(i)2(-/-) DCs have functional defects, influenced by strain background, that predispose to IBD. METHODS By breeding these strains to homozygosity for the first time, it became possible to study innate immunity in this animal model with more precision than ever before. Immature DCs were generated using bone marrow monoblasts cultured in the presence of GM-CSF (BMDCs), DC subsets sorted and responses to TLR9 activation were assayed. RESULTS In contrast to Galpha(i)2(-/-) B6, Galpha(i)2(-/-) 129 mice display accelerated onset and increased severity of colitis, abnormal mucosal DC distribution, accompanied by preponderance for Th1 and Th17-associated gut cytokine expression. TLR9 activation of BMDCs induces sustained p38 MAPK activation and greater Th1- and Th17-type cytokine secretion in both strains of Galpha(i)2-deficient compared to wildtype BMDCs. However, only B6 Galpha(i)2(-/-) BMDCs concomitantly produces IL-10 while Galpha(i)2(-/-) 129 BMDCs do not. CONCLUSIONS Loss of Galpha(i)2 promotes a Th1/Th17 phenotype and relative IL-10 insufficiency in Galpha(i)2(-/-) 129 BMDCs may account for the striking difference in disease.
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Affiliation(s)
- JA Peña
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030,Department of Pathology, Texas Children's Hospital, Houston, TX 77030
| | | | - PR Calkins
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030
| | - N Tatevian
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030,Department of Pathology, Texas Children's Hospital, Houston, TX 77030
| | - M Puppi
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030,Department of Pathology, Texas Children's Hospital, Houston, TX 77030
| | - MJ Finegold
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030,Department of Pathology, Texas Children's Hospital, Houston, TX 77030,To whom correspondence should be addressed: 6621 Fannin St. MC 1-2261, Houston, TX 77030. Phone: (832) 8241885. Fax: (832) 825 1032. e-mail:
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6
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Jin YZ, Thompson BD, Zhou ZY, Fu Y, Birnbaumer L, Wu MX. Reciprocal function of Galphai2 and Galphai3 in graft-versus-host disease. Eur J Immunol 2008; 38:1988-98. [PMID: 18521956 DOI: 10.1002/eji.200737738] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This study delineates specific functions of Galphai2 and Galphai3 in T cell mobilization during the development of graft-versus-host disease (GVHD) and reveals reciprocal effects of these two G proteins on the onset and morbidity of the disease. A deletion of Galphai2 hampered trafficking of pathogenic T cells from secondary lymphoid tissues to inflammatory sites and sufficiently prevented GVHD. In contrast, a severer disease was induced in mice adoptively transferred with Galphai3-deficient T cells than those mice transferred with wild-type T cells. In agreement with this, pathogenic Galphai2(-/-) T cells displayed a defect in response to CXCL10, CXCL11, and CCL5, whereas lack of Galphai3 augmented T effector cell chemotaxis induced by CXCL10 and CXCL11 and resulted in their preference of homing to the liver and colon. Absence of either Galphai also abrogated sphingosince-1-phosphate (S1P)-mediated inhibition of T cell chemokinesis and facilitated T cell homing and expansion in the spleen and mesenteric lymph nodes at the early phase of GVHD development, which is another key determinant in the severity and early onset of the disease in the mice infused with Galphai3(-/-) T cells. These observations underscore interplay between Galphai2 and Galphai3 and potentially provide a novel strategy to prevent GVHD by blocking T cell homing at early stages and T effector cell trafficking at later time points.
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Affiliation(s)
- Yong Zhu Jin
- Wellman Center of Photomedicine, Massachusetts General Hospital, and Department of Dermatology, Harvard Medical School, Boston, MA, USA
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7
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McPherson M, Wei B, Turovskaya O, Fujiwara D, Brewer S, Braun J. Colitis immunoregulation by CD8+ T cell requires T cell cytotoxicity and B cell peptide antigen presentation. Am J Physiol Gastrointest Liver Physiol 2008; 295:G485-92. [PMID: 18617557 PMCID: PMC2536787 DOI: 10.1152/ajpgi.90221.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Deficient immunoregulation by CD4+ T cells is an important susceptibility trait for inflammatory bowel disease, but the role of other regulatory cell types is less understood. This study addresses the role and mechanistic interaction of B cells and CD8+ T cells in controlling immune-mediated colitis. The genetic requirements for B cells and CD8+ T cells to confer protective immunoregulation were assessed by cotransfer with colitogenic Galphai2-/- T cells into immune-deficient mice. Disease activity in Galphai2-/- T cell recipients was evaluated by CD4+ T intestinal lymphocyte abundance, cytokine production levels, and large intestine histology. B cells deficient in B7.1/B7.2, CD40, major histocompatibility complex (MHC) II (Abb), or native B cell antigen receptor (MD4) were competent for colitis protection. However, transporter-1-deficient B cells failed to protect, indicating a requirement for peptide MHC I presentation to CD8+ T cells. CD8+ T cells deficient in native T cell receptor repertoire (OT-1) or cytolysis (perforin-/-) also were nonprotective. These finding reveal an integrated role for antigen-specific perforin-dependent CD8+ T cell cytotoxicity in colitis immunoregulatory and its efficient induction by a subset of mesenteric B lymphocytes.
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Affiliation(s)
- Michael McPherson
- Molecular Biology Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles; and La Jolla Institute for Allergy and Immunology, San Diego, California
| | - Bo Wei
- Molecular Biology Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles; and La Jolla Institute for Allergy and Immunology, San Diego, California
| | - Olga Turovskaya
- Molecular Biology Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles; and La Jolla Institute for Allergy and Immunology, San Diego, California
| | - Daisuke Fujiwara
- Molecular Biology Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles; and La Jolla Institute for Allergy and Immunology, San Diego, California
| | - Sarah Brewer
- Molecular Biology Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles; and La Jolla Institute for Allergy and Immunology, San Diego, California
| | - Jonathan Braun
- Molecular Biology Institute, Department of Pathology and Laboratory Medicine, University of California, Los Angeles; and La Jolla Institute for Allergy and Immunology, San Diego, California
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8
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Edwards RA, Wang K, Davis JS, Birnbaumer L. Role for epithelial dysregulation in early-onset colitis-associated colon cancer in Gi2-alpha-/- mice. Inflamm Bowel Dis 2008; 14:898-907. [PMID: 18340649 PMCID: PMC2729494 DOI: 10.1002/ibd.20414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Inflammatory bowel disease (IBD) is a risk factor for developing colorectal cancer but the mechanisms are poorly characterized. Mice lacking the G-protein alpha subunit Gi2-alpha spontaneously develop colitis and colon cancer with high penetrance. Compared to canonical Wnt/APC signaling-based animal models of colon cancer, the tumors in Gi2-alpha-/- mice more closely recapitulate the features of IBD-associated cancers seen in humans. They are predominantly right-sided, multifocal, mucinous, and arise from areas of flat dysplasia. METHODS In evaluating the potential contribution of epithelial Gi2-alpha signaling to this phenotype, we found that Gi2-alpha-/- colonic epithelium is hyperproliferative even before the onset of colitis, and resistant to the induction of apoptosis. We generated colon cancer cell lines overexpressing dominant-negative Gi2-alpha. RESULTS Like other cells lacking Gi2-alpha, these cells release less arachidonic acid, an important antiinflammatory and epithelial growth regulator. They are also hyperproliferative and resistant to camptothecin-induced apoptosis and caspase-3 activation. CONCLUSIONS The colitis-associated cancers in Gi2-alpha-/- mice appear very similar to those seen in human IBD patients, and Gi2-alpha is a direct negative regulator of colonic epithelial cell growth.
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Affiliation(s)
- Robert A. Edwards
- Departments of Pathology and Lab Medicine, University of California, Irvine, Irvine, California
| | - Kehui Wang
- Departments of Pathology and Lab Medicine, University of California, Irvine, Irvine, California
| | - Jennifer S. Davis
- Departments of Pathology and Lab Medicine, University of California, Irvine, Irvine, California
| | - Lutz Birnbaumer
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
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9
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Wei B, McPherson M, Turovskaya O, Velazquez P, Fujiwara D, Brewer S, Braun J. Integration of B cells and CD8+ T in the protective regulation of systemic epithelial inflammation. Clin Immunol 2008; 127:303-12. [PMID: 18282744 PMCID: PMC2478703 DOI: 10.1016/j.clim.2008.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 12/29/2007] [Accepted: 01/01/2008] [Indexed: 01/12/2023]
Abstract
Mechanisms that control abnormal CD4(+) T cell-mediated tissue damage are a significant factor in averting and resolving chronic inflammatory epithelial diseases. B cells can promote such immunoregulation, and this is thought to involve interaction with MHC II- or CD1-restricted regulatory T cells. The purpose of this study is to genetically define the interacting cells targeted by protective B cells, and to elucidate their regulatory mechanisms in CD4(+) T cell inflammation. Transfer of G alpha i2-/- CD3(+) T cells into lymphopenic mice causes a dose-dependent multi-organ inflammatory disease including the skin, intestine, and lungs. Disease activity is associated with elevated levels of serum TNF-alpha and IFN-gamma, and an activated IL-17 producing CD4(+) T cell population. Mesenteric node B cells from wild type mice suppress disease activity, serum cytokine expression, and levels of CD4(+) T cells producing TNF-alpha IFN-gamma, and IL-17. The protective function of B cells requires genetic sufficiency of IL-10, MHC I and TAP1. Regulatory B cells induce the expansion and activation of CD8(+) T cells, which is correlated with disease protection. These results demonstrate that CD8(+) T cells can ameliorate lymphopenic systemic inflammatory disease, through peptide/MHC I-dependent B cell interaction.
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Affiliation(s)
- Bo Wei
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Michael McPherson
- Molecular Biology Institute, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Olga Turovskaya
- La Jolla Institute for Allergy and Immunology, San Diego, CA 92121
| | - Peter Velazquez
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Daisuke Fujiwara
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Sarah Brewer
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
| | - Jonathan Braun
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
- Molecular Biology Institute, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 13-222, Los Angeles, CA 90095
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10
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Nemetz N, Abad C, Lawson G, Nobuta H, Chhith S, Duong L, Tse G, Braun J, Waschek JA. Induction of colitis and rapid development of colorectal tumors in mice deficient in the neuropeptide PACAP. Int J Cancer 2008; 122:1803-9. [PMID: 18098289 DOI: 10.1002/ijc.23308] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pituitary adenylyl cyclase activating peptide (PACAP) is expressed in central, sensory, autonomic, and enteric neurons. Although it classically acts as a neurotransmitter/neuromodulator, recent studies indicate that PACAP can also regulate immune function. To this effect, PACAP has been shown to reduce clinical symptoms and inflammation in mouse models of human immune-based diseases such as rheumatoid arthritis, Crohn's Disease, septic shock and multiple sclerosis. Despite these findings, the role of the endogenous peptide in regulating immune function is unknown. To determine if endogenous PACAP plays a protective role in inflammatory bowel disease (IBD) and IBD-associated colorectal cancer in mice, PACAP-deficient (KO) mice were subjected to 3 cycles of dextran sulfate sodium (DSS) in drinking water over 2 months, an established mouse model for colitis. Compared to wild type (WT) controls, PACAP KO mice exhibited more severe clinical symptoms of colitis and had significantly higher colonic inflammation on pathological examination. Moreover, 60% of the PACAP KO mice developed colorectal tumors with an aggressive-appearing pathology. Consistent with published data, DSS-treated WT mice did not develop such tumors. The results demonstrate a new mouse model which rapidly develops inflammation-associated colorectal cancer in the absence of a carcinogen.
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Affiliation(s)
- Nicole Nemetz
- Department of Laboratory Animal Medicine, David Geffen School of Medicine, Semel Institute for Neuroscience and Mental Retardation Research Center, University of California at Los Angeles, CA 90095, USA
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11
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Hoang B, Trinh A, Birnbaumer L, Edwards RA. Decreased MAPK- and PGE2-dependent IL-11 production in Gialpha2-/- colonic myofibroblasts. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1511-9. [PMID: 17332478 DOI: 10.1152/ajpgi.00307.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mice deficient in the G-protein alpha subunit G(i)alpha(2) spontaneously develop colitis and colon cancer. IL-11 is a pleiotropic cytokine known to protect the intestinal epithelium from injury in animal models of colitis and is produced by subepithelial myofibroblasts in response to inflammatory mediators including TGF-beta, IL-1beta, and PGE(2). Arachidonic acid release and subsequent PGE(2) production is significantly decreased in the colonic mucosa of G(i)alpha(2)-/- mice, and we hypothesized that this would affect mucosal IL-11 production. Mucosal levels of IL-11 were found to be significantly decreased in G(i)alpha(2)-/- mice despite the presence of mild colitis. Primary cultures of G(i)alpha(2)-/- intestinal and colonic myofibroblasts (IMF and CMF, respectively) produced less basal and TGF-beta or IL-1beta-stimulated IL-11 mRNA and protein than wild-type cells. Inhibitors of ERK or p38 MAPK activation dose dependently inhibited IMF and CMF IL-11 production in response to TGF-beta stimulation, whereas 16,16 dimethyl-PGE(2) and prostanoid receptor subtype-selective agonists induced IL-11 production. Treatment of animals with the EP4-specific agonist ONO-AE1-329 resulted in enhanced mucosal levels of IL-11, and increased IL-11 production by ex vivo cultured CMF. Modulation of cAMP levels produced diverging results, with enhancement of TGF-beta-induced IL-11 release in IMF pretreated with 8-Br-cAMP and inhibition in cells treated either with pertussis toxin or the PKA inhibitor H-89. These data suggest a physiological role for prostaglandins, MAPK signaling, and cAMP signaling for the production of myofibroblast-derived IL-11 in the mouse intestinal mucosa.
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MESH Headings
- 16,16-Dimethylprostaglandin E2/pharmacology
- Alprostadil/analogs & derivatives
- Alprostadil/pharmacology
- Animals
- Cells, Cultured
- Colon/cytology
- Colon/drug effects
- Colon/enzymology
- Colon/metabolism
- Cyclic AMP/metabolism
- Dinoprostone/metabolism
- Dose-Response Relationship, Drug
- Enzyme Activation
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Fibroblasts/drug effects
- Fibroblasts/enzymology
- Fibroblasts/metabolism
- Flavonoids/pharmacology
- GTP-Binding Protein alpha Subunit, Gi2/deficiency
- GTP-Binding Protein alpha Subunit, Gi2/genetics
- GTP-Binding Protein alpha Subunit, Gi2/metabolism
- Imidazoles/pharmacology
- Interleukin-11/genetics
- Interleukin-11/metabolism
- Interleukin-1beta/metabolism
- Intestine, Small/cytology
- Intestine, Small/drug effects
- Intestine, Small/enzymology
- Intestine, Small/metabolism
- Methyl Ethers/pharmacology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/metabolism
- Protein Kinase Inhibitors/pharmacology
- Pyridines/pharmacology
- RNA, Messenger/metabolism
- Receptors, Prostaglandin E/metabolism
- Receptors, Prostaglandin E, EP4 Subtype
- Signal Transduction/drug effects
- Transforming Growth Factor beta/metabolism
- p38 Mitogen-Activated Protein Kinases/metabolism
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Affiliation(s)
- Brian Hoang
- Dept. of Pathology, D449 Med Sci I, Univ. of California Irvine, Irvine, CA 92697-4800, USA
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12
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Thompson BD, Jin Y, Wu KH, Colvin RA, Luster AD, Birnbaumer L, Wu MX. Inhibition of G alpha i2 activation by G alpha i3 in CXCR3-mediated signaling. J Biol Chem 2007; 282:9547-9555. [PMID: 17289675 PMCID: PMC2366813 DOI: 10.1074/jbc.m610931200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) convey extracellular stimulation into dynamic intracellular action, leading to the regulation of cell migration and differentiation. T lymphocytes express G alpha(i2) and G alpha(i3), two members of the G alpha(i/o) protein family, but whether these two G alpha(i) proteins have distinguishable roles guiding T cell migration remains largely unknown because of a lack of member-specific inhibitors. This study details distinct G alpha(i2) and G alpha(i3) effects on chemokine receptor CXCR3-mediated signaling. Our data showed that G alpha(i2) was indispensable for T cell responses to three CXCR3 ligands, CXCL9, CXCL10, and CXCL11, as the lack of G alpha(i2) abolished CXCR3-stimulated migration and guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) incorporation. In sharp contrast, T cells isolated from G alpha(i3) knock-out mice displayed a significant increase in both GTPgammaS incorporation and migration as compared with wild type T cells when stimulated with CXCR3 agonists. The increased GTPgammaS incorporation was blocked by G alpha(i3) protein in a dose-dependent manner. G alpha(i3)-mediated blockade of G alpha(i2) activation did not result from G alpha(i3) activation, but instead resulted from competition or steric hindrance of G alpha(i2) interaction with the CXCR3 receptor via the N terminus of the second intracellular loop. A mutation in this domain abrogated not only G alpha(i2) activation induced by a CXCR3 agonist but also the interaction of G alpha(i3) to the CXCR3 receptor. These findings reveal for the first time an interplay of G alpha(i) proteins in transmitting G protein-coupled receptor signals. This interplay has heretofore been masked by the use of pertussis toxin, a broad inhibitor of the G alpha(i/o) protein family.
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MESH Headings
- Animals
- Cells, Cultured
- Chemokine CXCL10
- Chemokine CXCL11
- Chemokine CXCL9
- Chemokines, CXC/metabolism
- Female
- GTP-Binding Protein alpha Subunit, Gi2/antagonists & inhibitors
- GTP-Binding Protein alpha Subunit, Gi2/deficiency
- GTP-Binding Protein alpha Subunit, Gi2/metabolism
- GTP-Binding Protein alpha Subunit, Gi2/physiology
- GTP-Binding Protein alpha Subunits, Gi-Go/deficiency
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Receptors, CXCR3
- Receptors, Chemokine/metabolism
- Receptors, Chemokine/physiology
- Signal Transduction/genetics
- Signal Transduction/physiology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
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Affiliation(s)
- Brian D Thompson
- Wellman Center for Photomedicine, Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Yongzhu Jin
- Wellman Center for Photomedicine, Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Kevin H Wu
- Wellman Center for Photomedicine, Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Richard A Colvin
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Andrew D Luster
- Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Lutz Birnbaumer
- NIEHS, Transmembrane Signaling Group, Laboratory of Signal Transduction, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Mei X Wu
- Wellman Center for Photomedicine, Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114.
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13
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Abstract
In this issue of Cell, Lin et al. (2006) answer one of the long-standing questions in the TGFbeta field by identifying a phosphatase, PPM1A, that directly dephosphorylates Smad2 and Smad3 to limit their activation.
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Affiliation(s)
- Stephen H Schilling
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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14
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Cassan C, Piaggio E, Zappulla JP, Mars LT, Couturier N, Bucciarelli F, Desbois S, Bauer J, Gonzalez-Dunia D, Liblau RS. Pertussis Toxin Reduces the Number of Splenic Foxp3+Regulatory T Cells. THE JOURNAL OF IMMUNOLOGY 2006; 177:1552-60. [PMID: 16849462 DOI: 10.4049/jimmunol.177.3.1552] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pertussis toxin (PTx) is a bacterial toxin used to enhance the severity of experimental autoimmune diseases such as experimental autoimmune encephalomyelitis. It is known to promote permeabilization of the blood-brain barrier, maturation of APC, activation of autoreactive lymphocytes and alteration of lymphocyte migration. In this study, we show that i.v. injection of PTx in mice induces a decrease in the number of splenic CD4(+)CD25(+) regulatory T cells (Treg cells). Furthermore, PTx not only induces a depletion of the dominant CD4(+)CD25(+)Foxp3(+) subpopulation of splenic Treg cells, but also reduces to a similar extent the CD4(+)CD25(-)Foxp3(+) subpopulation. On a per cell basis, the suppressive properties of the remaining Treg cells are not modified by PTx treatment. The reduction in splenic Treg cells is associated with preferential migration of these cells to the liver. Additionally, Treg cells exhibit a high sensitivity to PTx-mediated apoptosis in vitro. Finally, in vivo depletion of Treg cells by injection of an anti-CD25 Ab, and PTx treatment, present synergistic experimental autoimmune encephalomyelitis exacerbating effects. Therefore, we identify a new effect of PTx and provide an additional illustration of the influence of microbial components on the immune system affecting the balance between tolerance, inflammation and autoimmunity.
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Affiliation(s)
- Cécile Cassan
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 563, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France
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15
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Lin X, Duan X, Liang YY, Su Y, Wrighton KH, Long J, Hu M, Davis CM, Wang J, Brunicardi FC, Shi Y, Chen YG, Meng A, Feng XH. PPM1A functions as a Smad phosphatase to terminate TGFbeta signaling. Cell 2006; 125:915-28. [PMID: 16751101 PMCID: PMC6309366 DOI: 10.1016/j.cell.2006.03.044] [Citation(s) in RCA: 379] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 01/31/2006] [Accepted: 03/23/2006] [Indexed: 01/07/2023]
Abstract
TGFbeta signaling controls diverse normal developmental processes and pathogenesis of diseases including cancer and autoimmune and fibrotic diseases. TGFbeta responses are generally mediated through transcriptional functions of Smads. A key step in TGFbeta signaling is ligand-induced phosphorylation of receptor-activated Smads (R-Smads) catalyzed by the TGFbeta type I receptor kinase. However, the potential of Smad dephosphorylation as a regulatory mechanism of TGFbeta signaling and the identity of Smad-specific phosphatases remain elusive. Using a functional genomic approach, we have identified PPM1A/PP2Calpha as a bona fide Smad phosphatase. PPM1A dephosphorylates and promotes nuclear export of TGFbeta-activated Smad2/3. Ectopic expression of PPM1A abolishes TGFbeta-induced antiproliferative and transcriptional responses, whereas depletion of PPM1A enhances TGFbeta signaling in mammalian cells. Smad-antagonizing activity of PPM1A is also observed during Nodal-dependent early embryogenesis in zebrafish. This work demonstrates that PPM1A/PP2Calpha, through dephosphorylation of Smad2/3, plays a critical role in terminating TGFbeta signaling.
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Affiliation(s)
- Xia Lin
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xueyan Duan
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yao-Yun Liang
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ying Su
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Katharine H. Wrighton
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jianyin Long
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Min Hu
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA
| | - Candi M. Davis
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jinrong Wang
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - F. Charles Brunicardi
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yigong Shi
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA
| | - Ye-Guang Chen
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Anming Meng
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Xin-Hua Feng
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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