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El Fiky A, Arch AE, Krolewski JJ. Intracellular domain of the IFNaR2 interferon receptor subunit mediates transcription via Stat2. J Cell Physiol 2005; 204:567-73. [PMID: 15717316 DOI: 10.1002/jcp.20305] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We recently demonstrated that IFNaR2, a subunit of the interferon receptor, can be proteolytically cleaved in response to interferon-alpha and other activators of protein kinase C. Cleavage occurs at multiple sites, via a mechanism similar to that employed by Notch and the Alzheimer's precursor protein, and releases the intracellular domain (ICD). In this study, we demonstrate that the IFNaR2 ICD, when fused to the yeast Gal4 DNA binding domain (Gal4DBD) selectively modulates transcription of four different promoters under the control of Gal4 upstream activating sequences. We previously showed that Stat2 binds constitutively to the ICD of IFNaR2, in a manner that is independent of tyrosine phosphorylation. Here, we show that ICD transcriptional modulation is dependent upon the carboxyl-terminal transactivation domain of Stat2. Specifically, complementing Stat2 deficient cells with wild-type Stat2 restored the ICD-mediated transcriptional effects while complementation with a mutant form of Stat2 lacking the transcriptional activation domain (TAD) did not. In addition, mutation of the Stat2 binding site on the ICD reduced the transcriptional activity of the Gal4DBD-ICD. Finally, we demonstrate that the activity of Jak1, a tyrosine kinase also known to bind to IFNaR2, is required for ICD-mediated transcriptional effects.
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Affiliation(s)
- Ashraf El Fiky
- Department of Pathology, College of Medicine, University of California, Irvine, Irvine, California, USA
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102
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Lassnig C, Sanchez CM, Egerbacher M, Walter I, Majer S, Kolbe T, Pallares P, Enjuanes L, Müller M. Development of a transgenic mouse model susceptible to human coronavirus 229E. Proc Natl Acad Sci U S A 2005; 102:8275-80. [PMID: 15919828 PMCID: PMC1140478 DOI: 10.1073/pnas.0408589102] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Human coronavirus (HCoV) 229E is a group 1 coronavirus and is specific to humans. So far, no animal model is available to study the pathogenesis of infection by HCoV-229E. We show here that the expression of aminopeptidase N (APN, also termed CD13), the receptor for HCoV-229E, is required but not sufficient to confer susceptibility in vivo. HCoV-229E infection was facilitated by crossing APN transgenic mice into signal transducers and activators of transcription (Stat) 1 null mice and by adaptation of HCoV-229E to grow in primary APN transgenic, Stat1 null fibroblasts. Double transgenic mice allow the study of human coronavirus group 1 infections in an animal model, in particular, viral tropism, replication, recombination, and spread in an immunocompromised situation. Furthermore, these mice provide an important tool for the evaluation of biosafety and efficacy of coronavirus-based vectors.
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MESH Headings
- Animals
- CD13 Antigens/genetics
- CD13 Antigens/metabolism
- Cells, Cultured
- Coronavirus 229E, Human/genetics
- Coronavirus 229E, Human/pathogenicity
- Coronavirus 229E, Human/physiology
- Disease Models, Animal
- Disease Susceptibility
- Fibroblasts
- Genotype
- Humans
- Mice
- Mice, Transgenic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Recombination, Genetic/genetics
- Species Specificity
- Transgenes/genetics
- Virus Replication
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Affiliation(s)
- Caroline Lassnig
- Ludwig Boltzmann Institute for Immunogenetic, Cytogenetic, and Molecular Genetic Research, 1210 Vienna, Austria
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103
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Tanabe Y, Nishibori T, Su L, Arduini RM, Baker DP, David M. Cutting edge: role of STAT1, STAT3, and STAT5 in IFN-alpha beta responses in T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2005; 174:609-13. [PMID: 15634877 DOI: 10.4049/jimmunol.174.2.609] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Engagement of the IFN-alphabeta receptor initiates multiple signaling cascades, including activation of the STAT. In this study, we demonstrate that IFN-alphabeta, although antiproliferative in wild-type CD4(+) or CD8(+) T cells, act as strong mitogens on their STAT1(-/-) counterparts. Furthermore, IFN-alphabeta exert little effect on apoptosis in wild-type cells, but are potent survival factors in the absence of STAT1. The antiapoptotic response in the absence of STAT1 is predominantly mediated by STAT3, and to a lesser extent by STAT5A/B. In contrast, the mitogenic IFN-alphabeta response gained through the absence of STAT1 is only marginally affected when STAT5A/B expression is also abrogated, but is completely dependent on STAT3 activation. These findings provide the first evidence for a function of STAT3 and STAT5A/B in the IFN-alphabeta response, and support a model in which the IFN-alphabeta receptor initiates both pro- and antiapoptotic responses through STAT1, and STAT3 and STAT5A/B, respectively.
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Affiliation(s)
- Yoshinari Tanabe
- Division of Biological Sciences, and Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
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104
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Clarke DTW, Irving AT, Lambley EH, Payne E, McMillan NAJ. A novel method for screening viral interferon-resistance genes. J Interferon Cytokine Res 2005; 24:470-7. [PMID: 15320960 DOI: 10.1089/1079990041689610] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Many viruses have evolved mechanisms to antagonize the interferon (IFN) system, targeting all the major components involved in receptor binding and signaling. Although a number of these vital proteins are homologous to cellular proteins involved in IFN downregulation (e.g., viral IFN regulatory factors [vIRFs]), many share little resemblance to known proteins. To determine the IFN-blocking properties of these proteins, functional assays are required. Here, we present a new and rapid functional screening method, based on the 2fTGH cell line, which is able to determine viral gene products that inhibit the IFN-alpha/Jak-Stat signaling pathway. Expression cloning of viral IFN-blocking genes into 2fTGH and consequent selection with IFN-alpha and 6-thioguanine result in the outgrowth of cells that are no longer responsive to IFN-alpha. We also demonstrate that selection occurs if members of the Jak-Stat signaling pathway are lost. To show the utility of our system, we have used a known suppressor of IFN signaling, the human papillomavirus (HPV) E7 gene. Expression of E7 causes the loss of ability of 2fTGH cells to respond to IFN-alpha treatment because of a functional disruption of the signaling pathway. This approach offers a new strategy for identifying novel viral genes or new functions of already described viral genes that have a role in IFN-alpha signaling inhibition.
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Affiliation(s)
- Daniel T W Clarke
- Centre for Immunology and Cancer Research, Princess Alexandra Hospital, University of Queensland, Brisbane, Australia
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105
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Affiliation(s)
- George R Stark
- Cleveland Clinic Foundation, Lerner Research Institute, Cleveland, Ohio 44195, USA.
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106
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Kalvakolanu DV. The GRIMs: a new interface between cell death regulation and interferon/retinoid induced growth suppression. Cytokine Growth Factor Rev 2004; 15:169-94. [PMID: 15110800 DOI: 10.1016/j.cytogfr.2004.01.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cytokines and vitamins play a central role in controlling neoplastic cell growth. The interferon (IFN) family of cytokines regulates antiviral, anti-tumor, antimicrobial, differentiation, and immune responses in mammals. Significant advances have been made with respect to IFN-induced signal transduction pathways and antiviral responses. However, the IFN-induced anti-tumor actions are poorly defined. Although IFNs themselves inhibit tumor growth, combination of IFNs with retinoids (a class of Vitamin A related compounds) strongly potentiates the IFN-regulated anti-tumor action in a number of cell types. To define the molecular mechanisms involved in IFN/retinoid (RA)-induced apoptosis we have employed a genetic approach and identified several critical genes. In this review, I provide the current picture of IFN- RA- and IFN/RA-regulated growth suppressive pathways. In particular, I focus on a novel set of genes, the genes-associated with retinoid-interferon induced mortality (GRIM). GRIMs may be novel types of tumor suppressors, useful as biological response markers and potentially novel targets for drug development.
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Affiliation(s)
- Dhananjaya V Kalvakolanu
- Molecular and Cell Biology Graduate Program, Department of Microbiology and Immunology, Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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107
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Bhardwaj N, Rosas LE, Lafuse WP, Satoskar AR. Leishmania inhibits STAT1-mediated IFN-gamma signaling in macrophages: increased tyrosine phosphorylation of dominant negative STAT1beta by Leishmania mexicana. Int J Parasitol 2004; 35:75-82. [PMID: 15619518 DOI: 10.1016/j.ijpara.2004.10.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 09/21/2004] [Accepted: 10/07/2004] [Indexed: 11/20/2022]
Abstract
Previous studies have demonstrated that Leishmania donovani attenuates STAT1-mediated signaling in macrophages; however it is not clear whether other species of Leishmania, which cause cutaneous disease, also interfere with macrophage IFN-gamma signaling. Therefore, we determined the effect of Leishmania major and Leishmania mexicana infection on STAT1-mediated IFN-gamma signaling pathway in J774A.1 and RAW264.7 macrophages. We found that both L. major and L. mexicana suppressed IFNgammaRalpha (alpha subunit of interferon gamma receptor) and IFN-gammaRbeta (beta subunit of interferon gamma receptor) expression, reduced levels of total Jak1 and Jak2, and down-regulated IFN-gamma-induced Jak1, Jak2 and STAT1 activation. The effect of L. mexicana infection on Jak1, Jak2 and STAT1 activation was more profound when compared with L. major. Although tyrosine phosphorylation of STAT1alpha was decreased in IFN-gamma stimulated macrophages infected with L. major or L. mexicana, those infected with L. mexicana showed a significant increase in phosphorylation of the dominant negative STAT1beta. These findings indicate that L. major and L. mexicana attenuate STAT1-mediated IFN-gamma signaling in macrophages. Furthermore, they also demonstrate that L. mexicana preferentially enhances tyrosine phosphorylation of dominant negative STAT1beta, which may be one of the several survival mechanisms used by this parasite to evade the host defense mechanisms.
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Affiliation(s)
- Neeti Bhardwaj
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
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108
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DeVries TA, Kalkofen RL, Matassa AA, Reyland ME. Protein Kinase Cδ Regulates Apoptosis via Activation of STAT1. J Biol Chem 2004; 279:45603-12. [PMID: 15322115 DOI: 10.1074/jbc.m407448200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Protein kinase Cdelta (PKCdelta) is required for mitochondria-dependent apoptosis; however, little is known about downstream effectors of PKCdelta in apoptotic cells. Here we show that activation of STAT1 is an early response to DNA damage and that STAT1 activation requires PKCdelta. Treatment of HeLa cells with etoposide results in phosphorylation of STAT1 on Ser(727) and the association of STAT1 with PKCdelta. Etoposide increases transcription from STAT1-dependent reporter constructs. Increased transcription, as well as STAT1 Ser(727) phosphorylation, can be blocked by inhibition or depletion of PKCdelta. To ask if STAT1 is required for PKCdelta-mediated apoptosis, we utilized U3A STAT1-deficient cells. Induction of apoptosis by PKCdelta is suppressed in U3A cells but can be rescued by co-transfection with STAT1alpha but not STAT1 mutated at Ser(727). Nuclear accumulation of STAT1, phospho-Ser(727) STAT1, and PKCdelta are detectable 30-60 min after treatment with etoposide. Nuclear localization is necessary for apoptosis, since a nuclear localization mutant of PKCdelta does not induce apoptosis in U3A cells reconstituted with STAT1alpha, and a nuclear localization mutant of STAT1 does not support PKCdelta-induced apoptosis in U3A cells. Our data identify STAT1 as a downstream target of PKCdelta and suggest that PKCdelta may regulate apoptosis by activation of STAT1 target genes.
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Affiliation(s)
- Tracie A DeVries
- Department of Craniofacial Biology, School of Dentistry, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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109
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Quiroga MF, Martínez GJ, Pasquinelli V, Costas MA, Bracco MM, Malbrán A, Olivares LM, Sieling PA, García VE. Activation of Signaling Lymphocytic Activation Molecule Triggers a Signaling Cascade That Enhances Th1 Responses in Human Intracellular Infection. THE JOURNAL OF IMMUNOLOGY 2004; 173:4120-9. [PMID: 15356162 DOI: 10.4049/jimmunol.173.6.4120] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
T cell production of IFN-gamma contributes to host defense against infection by intracellular pathogens, including mycobacteria. Lepromatous leprosy, the disseminated form of infection caused by Mycobacterium leprae, is characterized by loss of cellular response against the pathogen and diminished Th1 cytokine production. Relieving bacterial burden in Ag-unresponsive patients might be achieved through alternative receptors that stimulate IFN-gamma production. We have previously shown that ligation of signaling lymphocytic activation molecule (SLAM) enhances IFN-gamma in mycobacterial infection; therefore, we investigated molecular pathways leading from SLAM activation to IFN-gamma production in human leprosy. The expression of the SLAM-associated protein (an inhibitory factor for IFN-gamma induction) on M. leprae-stimulated cells from leprosy patients was inversely correlated to IFN-gamma production. However, SLAM ligation or exposure of cells from lepromatous patients to a proinflammatory microenvironment down-regulated SLAM-associated protein expression. Moreover, SLAM activation induced a sequence of signaling proteins, including activation of the NF-kappaB complex, phosphorylation of Stat1, and induction of T-bet expression, resulting in the promotion of IFN-gamma production, a pathway that remains quiescent in response to Ag in lepromatous patients. Therefore, our findings reveal a cascade of molecular events during signaling through SLAM in leprosy that cooperate to induce IFN-gamma production and strongly suggest that SLAM might be a focal point for therapeutic modulation of T cell cytokine responses in diseases characterized by dysfunctional Th2 responses.
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Affiliation(s)
- María F Quiroga
- Department of Microbiology, Parasitology, and Immunology, University of Buenos Aires School of Medicine, Buenos Aires, Argentina
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110
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Zhou L, Schandené L, Mordvinov VA, Chatelain P, Pradier O, Goldman M, Stordeur P. Trapidil inhibits monocyte CD40 expression by preventing IFN-γ-induced STAT1 S727 phosphorylation. Int Immunopharmacol 2004; 4:863-71. [PMID: 15182726 DOI: 10.1016/j.intimp.2004.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Revised: 12/04/2003] [Accepted: 03/12/2004] [Indexed: 11/26/2022]
Abstract
Trapidil is a triazolopyrimidine that has been found to prevent restenosis after vascular injury. Although its precise mode of action is still unclear, several biological effects have been described including inhibition of IFN-gamma-induced CD40 expression on monocytes. Herein, we investigated the molecular mechanisms by which Trapidil exerts this inhibitory action. First, we observed that the inhibition of CD40 expression is associated with the suppression of CD40 gene transcription, as demonstrated by a clear decrease of CD40 nuclear RNA (nRNA) levels and unchanged CD40 mRNA half-life. IFN-gamma-induced CD40 transcription has been shown to be mediated by STAT1alpha dimers (p91/p84) which, after nuclear translocation, bind to GAS elements present in the promoter of IFN-gamma responsive genes. Electrophoresis mobility shift assay (EMSA) with both STAT1 consensus and CD40 mGAS probes showed that Trapidil did not affect the DNA binding ability of STAT1 dimers. STAT1 dimerization and activation are conferred by upstream phosphorylation of two amino acid residues of the STAT1 protein. The subsequent studies on these two potential STAT1 phosphorylation sites (Tyr701, Ser727) revealed that Trapidil attenuated IFN-gamma-induced Ser727 but not Tyr701 phosphorylation. The inhibition of CD40 transcription by Trapidil could at least partially owing to the impaired Ser727 phosphorylation of STAT1, since IFN-gamma failed to trigger CD40 expression in U3A S727A cells, a cell line displaying a point mutation at the Ser727 site. Collectively, our results indicate that phosphorylation of STAT1 at the Ser727 site enhances CD40 transcription and that Trapidil might be used as a selective inhibitor that could differentially modulate STAT1 target genes.
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Affiliation(s)
- Ling Zhou
- Department of Immunology-Hematology-Transfusion, Erasme Hospital, Université Libre de Bruxelles, route de Lennik, 808, Brussels, B-1070, Belgium
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111
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Abstract
STAT2 is a transcription factor critical to the signal transduction pathway of type I interferons (e.g. IFNalpha). STAT2 resides primarily in the cytoplasm and is tyrosine-phosphorylated after IFNalpha binds to cell surface receptors. In response to tyrosine phosphorylation STAT2 rapidly localizes to the nucleus and acquires the ability to bind specific DNA targets in association with two other proteins, STAT1 and IFN regulatory factor-9 (IRF-9). To elucidate the mechanisms that regulate cellular localization of STAT2, we investigated STAT2 nuclear trafficking both prior to tyrosine phosphorylation and after phosphorylation. Prior to phosphorylation, STAT2 is primarily resident in the cytoplasm, however, we found that it dynamically shuttles between nuclear and cytoplasmic compartments. The nuclear translocation of latent unphosphorylated STAT2 was found to be dependent on its constitutive association with IRF-9, and the export of STAT2 from the nucleus was contingent upon the function of an intrinsic nuclear export signal within the carboxyl terminus of STAT2. STAT2 export could be inhibited with leptomycin B, indicating a nuclear export signal within STAT2 is recognized by the CRM1 exportin carrier. In contrast, following tyrosine phosphorylation, STAT2 dimerizes with phosphorylated STAT1 and accumulates in the nucleus. In the absence of STAT1, STAT2 does not accumulate in the nucleus. In addition, subsequent to nuclear import of phosphorylated STAT2, it redistributes to the cytoplasm within an hour coordinate with its dephosphorylation in the nucleus. The regulation of STAT2 nuclear trafficking is distinct from the previously characterized STAT1 factor.
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Affiliation(s)
- Gregg Banninger
- Graduate Program in Genetics, Stony Brook University, New York 11794-8691, USA
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112
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Athie-Morales V, Smits HH, Cantrell DA, Hilkens CMU. Sustained IL-12 signaling is required for Th1 development. THE JOURNAL OF IMMUNOLOGY 2004; 172:61-9. [PMID: 14688310 DOI: 10.4049/jimmunol.172.1.61] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
STAT4 is an essential transcription factor for Th1 cell development. IL-12 and IFN-alpha both activate STAT4, but with different kinetics. In this study we compared their capacities to drive differentiation of human naive Th cells toward the Th1 phenotype. The Th1-polarizing activity of IFN-alpha was much weaker than that of IL-12, correlating with a marked difference in the kinetics of STAT4 activation; the response to IL-12 was sustained (>48 h), whereas the response to IFN-alpha was transient (4 h). The continuous presence of IL-12 was required for sustained STAT4 activation. Similarly, optimal Th1 polarization was only achieved upon prolonged exposure to IL-12 and could not be induced by a transient IL-12 pulse. Furthermore, the cytokine IL-2 potentiated sustained IL-12/STAT4 responses through up-regulation of IL-12R expression and synergized with IL-12 in driving Th1 cell development. Transient IFN-alpha responses, on the other hand, were not prolonged by IL-2. IFN-alpha treatment induced down-regulation of IFN-alphabeta receptor subunit 1, rendering cells refractory to IFN-alpha, but did not trans-inhibit the IL-12/STAT4 response. These data indicate that sustained IL-12 signaling is essential for optimal Th1 cell development and that transient activation of STAT4 in response to IFN-alpha may explain the poor Th1-polarizing capacity of this cytokine. Collectively these data show that the duration of cytokine signaling is important for determining the biological response.
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Affiliation(s)
- Veronica Athie-Morales
- Lymphocyte Activation Laboratory and Biochemical Regulatory Mechanisms Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
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113
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Meyer T, Hendry L, Begitt A, John S, Vinkemeier U. A Single Residue Modulates Tyrosine Dephosphorylation, Oligomerization, and Nuclear Accumulation of Stat Transcription Factors. J Biol Chem 2004; 279:18998-9007. [PMID: 15010467 DOI: 10.1074/jbc.m400766200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The NH(2) terminus of Stat proteins forms a versatile protein interaction domain that is believed to use discrete surfaces to mediate oligomerization and tyrosine dephosphorylation of Stat dimers. Here we show for Stat1 and Stat5a/b that these interfaces overlap and need to be reassigned to an unrelated region of the N-domain. Unexpectedly, our study showed for Stat1 that defective oligomerization of DNA-bound dimers was associated with prolonged interferon-induced nuclear accumulation. This uncoupling of DNA binding and nuclear retention was explained by the concomitant dephosphorylation deficiency that both Stat1 and Stat5a/b have in common and that for Stat1 was due to defective dephosphorylation by the phosphatase TC45. Furthermore, diminished N-domain-mediated oligomerization affected transcriptional activation by both Stat1 and Stat5a/b in a promoter-specific manner. DNA binding analysis indicated that oligomerization of Stats on DNA may be common, irrespective of the presence of multiple canonical binding sites. Accordingly, also transcription from promoters with only a single discernable gamma-activated sequence site was negatively effected by reduced tetramerization. Thus, these results indicate that defective oligomerization cannot generally be compensated for by enhanced tyrosine phosphorylation and prolonged nuclear accumulation. In addition, these data clarify the role of DNA binding in nuclear retention of Stat1.
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Affiliation(s)
- Thomas Meyer
- Abteilung Zelluläre Signalverarbeitung, Forschungsinstitut für Molekulare Pharmakologie, Freie Universität Berlin, 13125 Berlin, Germany
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114
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Affiliation(s)
- Stefan Grimm
- Max-Planck-Institute for Biochemistry, Am Klopferspitz 18a, 82152 Martinsried, Germany.
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115
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Alvarez GR, Zwilling BS, Lafuse WP. Mycobacterium avium inhibition of IFN-gamma signaling in mouse macrophages: Toll-like receptor 2 stimulation increases expression of dominant-negative STAT1 beta by mRNA stabilization. THE JOURNAL OF IMMUNOLOGY 2004; 171:6766-73. [PMID: 14662881 DOI: 10.4049/jimmunol.171.12.6766] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mycobacterial infections of macrophages have been shown to inhibit the ability of the macrophage to respond to IFN-gamma. We previously reported that Mycobacterium avium infection of mouse macrophages decreases IFN-gamma-induced STAT1 tyrosine phosphorylation and STAT1 DNA binding. Because macrophages respond to M. avium through Toll-like receptor 2 (TLR2), we determined whether TLR2 stimulation inhibits the response to IFN-gamma. Treatment of mouse RAW264.7 macrophages with TLR2 agonists inhibited the induction of IFN-gamma-inducible genes by IFN-gamma. In contrast to M. avium infection, TLR2 agonists did not inhibit the IFN-gamma induction of DNA-binding activity of STAT1 and the tyrosine phosphorylation of STAT1alpha. Instead, IFN-gamma induction of RAW264.7 cells treated with TLR2 agonists resulted in an increase in the tyrosine phosphorylation of the dominant-negative STAT1beta. TLR2 stimulation of RAW264.7 cells increased both STAT1beta protein and mRNA expression, suggesting that the increased STAT1beta phosphorylation results from increased STAT1beta expression. Because STAT1alpha and STAT1beta mRNA have different 3' untranslated regions, and 3' untranslated regions can regulate mRNA stability, we examined the effects of TLR2 stimulation on mRNA stability. TLR2 stimulation of RAW264.7 cells increased the stability of STAT1beta mRNA, while not affecting the stability of STAT1alpha mRNA. The ability of STAT1beta to function as a dominant negative was confirmed by overexpression of STAT1beta in RAW264.7 macrophages by transient transfection, which inhibited IFN-gamma-induced gene expression. These findings suggest that M. avium infection of mouse macrophages inhibits IFN-gamma signaling through a TLR2-dependent increase in STAT1beta expression by mRNA stablization and a TLR2-independent inhibition of STAT1 tyrosine phosphorylation.
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Affiliation(s)
- Gail R Alvarez
- Department of Molecular Virology, Immunology, and Medical Genetics, Ohio State University, Columbus, OH 43210, USA
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116
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Abstract
More than a half a century ago, interferons (IFN) were identified as antiviral cytokines. Since that discovery, IFN have been in the forefront of basic and clinical cytokine research. The pleiotropic nature of these cytokines continues to engage a large number of investigators to define their actions further. IFN paved the way for discovery of Janus tyrosine kinase (JAK)-signal transducing activators of transcription (STAT) pathways. A number of important tumor suppressive pathways are controlled by IFN. Several infectious pathogens counteract IFN-induced signaling pathways. Recent studies indicate that IFN activate several new protein kinases, including the MAP kinase family, and downstream transcription factors. This review not only details the established IFN signaling paradigms but also provides insights into emerging alternate signaling pathways and mechanisms of pathogen-induced signaling interference.
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Affiliation(s)
- Dhananjaya V Kalvakolanu
- Molecular and Cellular Biology Graduate Program, Greenebaum Cancer Center, Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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117
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Zhang Y, Gui J. Molecular characterization and IFN signal pathway analysis of Carassius auratus CaSTAT1 identified from the cultured cells in response to virus infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2004; 28:211-227. [PMID: 14642888 DOI: 10.1016/s0145-305x(03)00138-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Type I interferon (IFN) exerts its pleiotropic effects mainly through the JAK-STAT signaling pathway, which is presently best described in mammals. By subtractive suppression hybridization, two fish signaling factors, JAK1 and STAT1, had been identified in the IFN-induced crucian carp Carassius auratus L. blastulae embryonic (CAB) cells after treatment with UV-inactivated grass carp hemorrhagic virus (GCHV). Further, the full-length cDNA of STAT1, termed CaSTAT1, was obtained. It contains 2926 bp and encodes a protein of 718 aa. CaSTAT1 is most similar to rat STAT1 with 59% identity overall and displays all highly conserved domains that the STAT family possesses. Like human STAT1beta, it lacks the C-terminus acting as transcriptional activation domain in mammals. By contrast, only a single transcript was detected in virus-induced CAB cells. Expression analysis showed that CaSTAT1 could be activated by stimulation of CAB cells with poly I:C, active GCHV, UV-inactivated GCHV or CAB IFN, and displayed diverse expression patterns similar to that of mammalian STAT1. Additionally, the expression of an antiviral gene CaMx1 was also induced under the same conditions, and expression difference between CaSTAT1 and CaMx1 was revealed by induction of CAB IFN. These results provide molecular evidence supporting the notion that the fish IFN signaling transduction pathway is similar to that in mammals. Fish IFN exerts its multiple functions, at least antiviral action, through a JAK-STAT pathway.
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Affiliation(s)
- Yibing Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Department of Fish Genetics and Breeding, Institute of Hydrobiology, Wuhan Center for Developmental Biology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China
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118
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Affiliation(s)
- Ke Shuai
- Division of Hematology-Oncology, Department of Medicine, University of California, Los Angeles, California 90095, USA.
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119
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Affiliation(s)
- Patrick P McDonald
- Pulmonary Division, Faculty of Medicine, Université de Sherbrooke Sherbrooke, Québec JIH 5N4, Canada
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120
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Nishibori T, Tanabe Y, Su L, David M. Impaired development of CD4+ CD25+ regulatory T cells in the absence of STAT1: increased susceptibility to autoimmune disease. ACTA ACUST UNITED AC 2003; 199:25-34. [PMID: 14699080 PMCID: PMC1193645 DOI: 10.1084/jem.20020509] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Type I and II interferons (IFNs) exert opposing effects on the progression of multiple sclerosis, even though both IFNs use the signal transducer and activator of transcription 1 (STAT1) as a signaling mediator. Here we report that STAT1-deficient mice expressing a transgenic T cell receptor against myelin basic protein spontaneously develop experimental autoimmune encephalomyelitis with dramatically increased frequency. The heightened susceptibility to this autoimmune disease appears to be triggered by a reduced number as well as a functional impairment of the CD4+ CD25+ regulatory T cells in STAT1-deficient animals. Adoptive transfer of wild-type regulatory T cells into STAT1-deficient hosts is sufficient to prevent the development of autoimmune disease. These results demonstrate an essential role of STAT1 in the maintenance of immunological self-tolerance.
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Affiliation(s)
- Takeaki Nishibori
- Department of Biology, University of California San Diego, Bonner Hall 3138, 9500 Gilman Drive, La Jolla, CA 92093, USA
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121
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Nusinzon I, Horvath CM. Interferon-stimulated transcription and innate antiviral immunity require deacetylase activity and histone deacetylase 1. Proc Natl Acad Sci U S A 2003; 100:14742-7. [PMID: 14645718 PMCID: PMC299790 DOI: 10.1073/pnas.2433987100] [Citation(s) in RCA: 228] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The use of histone deacetylase (HDAC) inhibitors has revealed an essential role for deacetylation in transcription of IFN-responsive genes. The HDAC1 protein associates with both signal transducer and activator of transcription (STAT) 1 and STAT2, and IFN-alpha stimulation induces deacetylation of histone H4. Inhibition of HDAC1 by small interfering RNA (siRNA) decreases IFN-alpha responsiveness whereas expression of HDAC1 augments the IFN-alpha response, demonstrating that HDAC1 modulates IFN-alpha-induced transcription. Importantly, the innate antiviral response is inhibited in the absence of deacetylase activity. The requirement for deacetylase is shared by IFN-gamma transcription response and may represent a general requirement for STAT-dependent gene expression.
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Affiliation(s)
- Inna Nusinzon
- Immunobiology Center, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1630, New York, NY 10029, USA
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122
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Sironi JJ, Ouchi T. STAT1-induced apoptosis is mediated by caspases 2, 3, and 7. J Biol Chem 2003; 279:4066-74. [PMID: 14623896 DOI: 10.1074/jbc.m307774200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
STAT1 (signal transducer and activator of transcription 1) has been implicated as a mediator of a variety of biological responses in response to stimulation by specific growth factors and cytokines. To understand better the role of STAT1 in the interferon-gamma (IFN-gamma)-induced phenotype, we generated an active form of STAT1 (STAT1C) by substituting Cys residues for both Arg-656 and Asn-658 within the C-terminal loop of the STAT1 SH2 domain. The IFN-gamma activation site element was stimulated and bound efficiently by STAT1C without IFN-gamma treatment. STAT1C was found to be tyrosine-phosphorylated in the nucleus for more than 30 h after IFN-gamma stimulation. STAT1-negative U3A cells reexpressing STAT1C showed retarded cell growth and underwent apoptosis when treated with IFN-gamma. Further analysis demonstrated that apoptosis was preceded by proteolytic cleavage of caspases 2, 3, and 7, and wild type STAT1 also induced cleavage of caspase 7 when expressed in STAT1-negative U3A cells, indicating that STAT1C augments potential activity of wild type STAT1. Studies with cycloheximide treatment showed that protein synthesis induced in the first 24 h after IFN-gamma treatment was required for apoptosis under these conditions. Finally, we found that STAT1C-induced apoptosis was, in part, mediated by caspase 2, 3, and 7 because benzyloxycarbonyl-valyl-aspartyl-valyl-alanyl-aspartic acid fluoromethyl ketone (Z-VDVAD-FMK) treatment partially blocked apoptosis. These results suggest that prolonged nuclear localization of activated STAT1 results in apoptosis involving specific regulation of caspase pathway.
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Affiliation(s)
- Juan J Sironi
- Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York University, New York, New York 10029, USA
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123
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Hilkens CMU, Schlaak JF, Kerr IM. Differential Responses to IFN-α Subtypes in Human T Cells and Dendritic Cells. THE JOURNAL OF IMMUNOLOGY 2003; 171:5255-63. [PMID: 14607926 DOI: 10.4049/jimmunol.171.10.5255] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Type I IFNs (IFN-alphabeta) constitute a family of cytokines that have important antiviral and immunoregulatory properties and have been successfully used in the treatment of a wide variety of diseases. There are 12 functional human IFN-alpha subtypes and one IFN-beta subtype that signal through the common cell surface IFN-alphabetaR. To date, virtually no information is available on the specificity of IFN-alpha responses in immune cells. In this study, Janus kinase/STAT signaling and transcriptional responses to selected IFN-alpha subtypes in human T cells and dendritic cells were analyzed. Evidence for IFN-alpha subtype and cell type specificity was found. Also, differences between kinetics of expression of IFN-stimulated genes (ISGs) and in the requirements of individual ISGs for additional signaling pathways were observed. In particular, IFN-gamma-inducible protein-10 (IP-10), a key chemokine in Th1-type inflammatory diseases, was differentially regulated. In dendritic cells, it was highly induced by IFN-alpha2 and IFN-alpha21 but much less efficiently by IFN-alpha1. It was only marginally induced by these subtypes in T cells. In marked contrast to other ISGs analyzed, optimum induction of IP-10 was dependent on activation of p38 kinase(s). The observed variations (subtype-, cell type-, and ISG-related differentials) provide further insight into the complexity and plasticity of the IFN-alphabeta response. Furthermore, the novel observation that IFN-alpha1 poorly induces IP-10 is potentially of clinical importance, because this subtype may be more beneficial in cases where Th1-mediated side effects (e.g., exacerbation of autoimmune diseases) are not desirable.
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Affiliation(s)
- Catharien M U Hilkens
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
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124
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Zakharova N, Lymar ES, Yang E, Malik S, Zhang JJ, Roeder RG, Darnell JE. Distinct transcriptional activation functions of STAT1alpha and STAT1beta on DNA and chromatin templates. J Biol Chem 2003; 278:43067-73. [PMID: 12939262 DOI: 10.1074/jbc.m308166200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Interferon-induced transcription depends upon tyrosine phosphorylation, subsequent dimerization, and binding to DNA of STAT1. Other factors, including but not necessarily limited to CBP/p300, then bind within the C-terminal 38 amino acid transactivation domain (TAD) to activate transcription. We show that both tyrosine-phosphorylated STAT1alpha (full-length wild-type protein) and STAT1beta (lacking the TAD) stimulate in vitro transcription on a naked DNA template. Furthermore, in a system with purified proteins and naked DNA, STAT1alpha- and STAT1beta-dependent transcription is stimulated by the TRAP/Mediator co-activator complex. Thus STAT1, through some site other than the C-terminal TAD, can interact with TRAP/Mediator or some intermediate protein. Although both STAT1alpha and STAT1beta bind to known STAT sites within in vitro assembled chromatin templates, only STAT1alpha, and not STAT1beta, in cooperation with p300 and acetyl-CoA, stimulated in vitro transcription from chromatin. After interferon-gamma treatment, cells recruit STAT1alpha or -beta to the chromosomal interferon-1 gene, but only STAT1alpha-containing cells recruit p300 and stimulate transcription. We conclude that chromatin remodeling by p300 in vivo makes TRAP/Mediator effective in stimulating transcription.
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Affiliation(s)
- Natalia Zakharova
- Laboratories of Molecular Cell Biology and Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021, USA
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125
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Yokota SI, Yokosawa N, Kubota T, Okabayashi T, Arata S, Fujii N. Suppression of thermotolerance in mumps virus-infected cells is caused by lack of HSP27 induction contributed by STAT-1. J Biol Chem 2003; 278:41654-60. [PMID: 12917439 DOI: 10.1074/jbc.m305701200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Viral infection modulates the regulation of apoptosis in host cells. Here, we report a novel mechanism by which human cells infected with mumps virus become susceptible to apoptosis caused by extracellular stresses. Mumps virus stimulates proteasome-dependent degradation of STAT-1 by action of viral accessory protein V, resulting in a severe decrease in STAT-1 protein in infected cells. We exposed mumps virus-infected and uninfected cells to heat and chemical stress. The infected cells failed to acquire resistance to apoptotic stimuli (thermotolerance) after exposure to these mild stresses. The induction of HSP27 by stress exposure was dramatically suppressed in the infected cells, but HSP70 induction was not affected. STAT-1 was required for transcriptional activation of the HSP27 gene, but not for the HSP70 gene, and cDNA transfection of STAT-1 in mumps virus-infected cells restored thermotolerance. Phosphorylated heat shock factor-1 (HSF-1) and STAT-1 phosphorylated on neither tyrosine nor serine residues were co-transported to the nucleus in response to stress. Furthermore, overexpression of unphosphorylatable mutants of STAT-1 also restored thermotolerance in mumps virus-infected cells. These lines of evidence indicate that the induction of HSP27 by stress requires STAT-1 in addition to the activated HSF-1. Furthermore, STAT-1 required for the induction of HSP27 worked independent to its phosphorylation. Thus, HSP27-dependent thermotolerance is suppressed by mumps virus infection through the destruction of STAT-1. The lack of thermotolerance should allow the infected cells to be eliminated by apoptosis and might be a host defense against viral infection.
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Affiliation(s)
- Shin-ichi Yokota
- Department of Microbiology, Sapporo Medical University School of Medicine, Chuo-ku, Sapporo 060-8556, Japan
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126
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Meyer T, Marg A, Lemke P, Wiesner B, Vinkemeier U. DNA binding controls inactivation and nuclear accumulation of the transcription factor Stat1. Genes Dev 2003; 17:1992-2005. [PMID: 12923054 PMCID: PMC196254 DOI: 10.1101/gad.268003] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cytokine-dependent gene transcription greatly depends on the tyrosine phosphorylation ("activation") of Stat proteins at the cell membrane. This rapidly leads to their accumulation in the nucleus by an unknown mechanism. We performed microinjections of recombinant Stat1 protein to show that nuclear accumulation of phosphorylated Stat1 can occur without cytokine stimulation of cells. Microinjection of Stat1 antibody and treatment of cells with kinase or phosphatase inhibitors revealed that nuclear accumulation is a highly dynamic process sustained by Stat1 nucleocytoplasmic cycling and continuous kinase activity. By characterizing nuclear accumulation mutants, it is demonstrated that nuclear import and nuclear retention are two separate steps leading up to nuclear accumulation, with nonspecific DNA binding of activated Stat1 being sufficient for nuclear retention. Critical for nuclear buildup of Stat1 and the subsequent nuclear export is the point of time of tyrosine dephosphorylation, because our data indicate that activated Stat1 is incapable of leaving the nucleus and requires dephosphorylation to do so. It is demonstrated that the inactivation of Stat1 is controlled by its exchange reaction with DNA, whereby DNA binding protects Stat1 from dephosphorylation in a sequence-specific manner. Thus, during nuclear accumulation, a surprisingly simple mechanism integrates central aspects of cytokine-dependent gene regulation, for example, receptor monitoring, promoter occupancy, and transcription factor inactivation.
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Affiliation(s)
- Thomas Meyer
- Abteilung Zelluläre Signalverarbeitung, Freie Universität Berlin, Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany
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127
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Kincaid EZ, Ernst JD. Mycobacterium tuberculosis exerts gene-selective inhibition of transcriptional responses to IFN-gamma without inhibiting STAT1 function. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:2042-9. [PMID: 12902509 DOI: 10.4049/jimmunol.171.4.2042] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mycobacterium tuberculosis is a highly successful human pathogen. A major component of this success is the pathogen's ability to avoid eradication by the innate and adaptive immune responses throughout the course of infection. IFN-gamma, a potent activator of the microbicidal activities of macrophages, is essential for control of M. tuberculosis infection, but is unable to stimulate macrophages to kill M. tuberculosis. We have found that infection of the human monocytic cell line, THP-1, resulted in reduced cellular responses to IFN-gamma, manifested as impaired induction of CD64 surface expression and transcription. This defect in transcription occurred despite normal activation of STAT1 in infected macrophages: there was no decrease in STAT1 tyrosine or serine phosphorylation, nuclear translocation, or binding of a minimal IFN-gamma response sequence. Assays of STAT1 function in M. tuberculosis-treated cells also revealed no defect in activation of a minimal gamma-activated sequence construct or STAT1 recruitment to and binding at the endogenous CD64 promoter. In addition, M. tuberculosis did not affect histone acetylation at the CD64 promoter. The inhibition of transcription was gene selective: while transcription of CD64 and class II transactivator were decreased, certain other IFN-gamma-responsive genes either were unaffected or were increased by M. tuberculosis. These results indicate that M. tuberculosis inhibits the response to IFN-gamma by a mechanism distinct from either suppressor of cytokine signaling-1 inhibition of STAT1 phosphorylation or protein inhibitor of activated STAT interference with DNA binding, and indicate that other mechanisms of inhibition of IFN-gamma responses remain to be discovered.
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MESH Headings
- DNA-Binding Proteins/antagonists & inhibitors
- DNA-Binding Proteins/metabolism
- DNA-Binding Proteins/physiology
- Dimerization
- Down-Regulation/genetics
- Down-Regulation/immunology
- Humans
- Interferon-gamma/antagonists & inhibitors
- Interferon-gamma/genetics
- Interferon-gamma/physiology
- Mycobacterium tuberculosis/immunology
- Nuclear Proteins
- Promoter Regions, Genetic/immunology
- Protein Binding/genetics
- Protein Binding/immunology
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/biosynthesis
- RNA, Messenger/metabolism
- Receptors, IgG/antagonists & inhibitors
- Receptors, IgG/biosynthesis
- Receptors, IgG/genetics
- Receptors, IgG/metabolism
- STAT1 Transcription Factor
- Signal Transduction/genetics
- Signal Transduction/immunology
- Trans-Activators/antagonists & inhibitors
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Trans-Activators/physiology
- Transcription, Genetic/immunology
- Tumor Cells, Cultured
- Up-Regulation/genetics
- Up-Regulation/immunology
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Affiliation(s)
- Eleanor Z Kincaid
- Biomedical Sciences Graduate Program and Division of Infectious Diseases, University of California, San Francisco, CA 94143, USA
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128
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Zhang J, Yang J, Roy SK, Tininini S, Hu J, Bromberg JF, Poli V, Stark GR, Kalvakolanu DV. The cell death regulator GRIM-19 is an inhibitor of signal transducer and activator of transcription 3. Proc Natl Acad Sci U S A 2003; 100:9342-7. [PMID: 12867595 PMCID: PMC170920 DOI: 10.1073/pnas.1633516100] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
GRIM-19 (gene associated with retinoid-IFN-induced mortality 19), isolated as a cell death activator in a genetic screen used to define mechanisms involved in IFN-beta- and retinoic acid-induced cell death, codes for a approximately 16-kDa protein that induces apoptosis in a number of cell lines. Antisense ablation of GRIM-19 caused resistance to cell death induced by IFN plus retinoic acid and conferred a growth advantage to cells. To understand the molecular bases for its cell death regulatory activity, we used a yeast two-hybrid screen and identified that the transcription factor STAT3 (signal transducer and activator of transcription 3) binds to GRIM-19. GRIM-19 inhibits transcription driven by activation of STAT3, but not STAT1. It neither inhibits the ligand-induced activation of STAT3 nor blocks its ability to bind to DNA. Mutational analysis indicates that the transactivation domain of STAT3, especially residue S727, is required for GRIM-19 binding. Because GRIM-19 does not bind significantly to other STATs, our studies identify a specific inhibitor of STAT3. Because constitutively active STAT3 up-regulates antiapoptotic genes to promote tumor survival, its inhibition by GRIM-19 also demonstrates an antioncogenic effect exerted by biological therapeutics.
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Affiliation(s)
- Jun Zhang
- Greenebaum Cancer Center, Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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129
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Strähle L, Garcin D, Le Mercier P, Schlaak JF, Kolakofsky D. Sendai virus targets inflammatory responses, as well as the interferon-induced antiviral state, in a multifaceted manner. J Virol 2003; 77:7903-13. [PMID: 12829830 PMCID: PMC161935 DOI: 10.1128/jvi.77.14.7903-7913.2003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We have used cDNA arrays to compare the activation of various cellular genes in response to infection with Sendai viruses (SeV) that contain specific mutations. Three groups of cellular genes activated by mutant SeV infection, but not by wild-type SeV, were identified in this way. While some of these genes are well known interferon (IFN)-stimulated genes, others, such as those for interleukin-6 (IL-6) and IL-8, are not directly induced by IFN. The gene for beta IFN (IFN-beta), which is critical for initiating an antiviral response, was also specifically activated in mutant SeV infections. The SeV-induced activation of IFN-beta was found to depend on IFN regulatory factor 3, and the activation of all three cellular genes was independent of IFN signaling. Mutations that disrupt four distinct elements in the SeV genome (the leader RNA, two regions of the C protein, and the V protein) all lead to enhanced levels of IFN-beta mRNA, and at least three of these viral genes also appear to be involved in preventing activation of IL-8. Our results suggest that SeV targets the inflammatory and adaptive immune responses as well as the IFN-induced intracellular antiviral state by using a multifaceted approach.
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Affiliation(s)
- Laura Strähle
- Department of Genetics and Microbiology, University of Geneva School of Medicine, CMU, 9 Avenue de Champel, CH-1211 Geneva, Switzerland
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130
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Dimberg A, Karlberg I, Nilsson K, Oberg F. Ser727/Tyr701-phosphorylated Stat1 is required for the regulation of c-Myc, cyclins, and p27Kip1 associated with ATRA-induced G0/G1 arrest of U-937 cells. Blood 2003; 102:254-61. [PMID: 12637327 DOI: 10.1182/blood-2002-10-3149] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
All-trans retinoic acid (ATRA)-induced growth arrest of myeloid cells is associated with a sequential regulation of cyclins and cyclin-dependent kinase inhibitors (CKIs), which modulates the cell cycle machinery and inhibits the G1-S phase progression. ATRA treatment of myeloid cells induces up-regulation and tyrosine phosphorylation of Stat1, a member of the STAT (signal transducer and activator of transcription) transcription factor family that has been implicated in growth arrest in response to interferons. We have previously shown that ATRA-induced cell cycle arrest is dependent on tyrosinephosphorylated Stat1. In this study, we show that there is a basal level of Stat1 Ser727 phosphorylation in U-937 cells, which is transiently increased in response to ATRA treatment. Using Stat1Ser727Ala-expressing sublines, we provide evidence that Ser727 phosphorylation of Stat1 is required for ATRA-induced growth arrest. To shed further light on the role of Stat1 in ATRA-induced cell cycle arrest, cyclin and CKI expression was analyzed during ATRA treatment in U-937 sublines expressing Stat1Ser727Ala and Stat1Tyr701Phe. Our results show that Ser727/Tyr701-phosphorylated Stat1 plays a key role as a prerequisite for the ATRA-induced down-regulation of c-Myc; cyclins A, B, D2, D3, and E; and the simultaneous up-regulation of p27Kip1, associated with arrest in the G0/G1 phase of the cell cycle.
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Affiliation(s)
- Anna Dimberg
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, S-751 85 Uppsala, Sweden
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131
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Jackson DP, Watling D, Rogers NC, Banks RE, Kerr IM, Selby PJ, Patel PM. The JAK/STAT pathway is not sufficient to sustain the antiproliferative response in an interferon-resistant human melanoma cell line. Melanoma Res 2003; 13:219-29. [PMID: 12777975 DOI: 10.1097/00008390-200306000-00001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The mechanism of resistance of malignant melanoma to treatment with interferon-alpha is unknown, and currently there is no reliable method of predicting response. Signalling via the JAK/STAT pathway is known to mediate many interferon-regulated events and has been implicated in mediating the antiproliferative response. The objective of this study was to determine whether defects in JAK/STAT signalling may be responsible for interferon resistance. The in vitro response to interferon was determined in a panel of established melanoma cell lines, and the components and functioning of the JAK/STAT pathway were examined in sensitive and resistant cell lines. Two melanoma cell lines, characterized as sensitive (MM418) and resistant (MeWo) to the antiproliferative effect of interferon, were both shown by Western blotting to possess all the protein components of the JAK/STAT pathway, and were shown to be capable of producing functional transcription factors using an electrophoretic mobility shift assay and a ribonuclease protection assay of known interferon-induced genes. In addition, both cell lines had intact antiviral and HLA upregulation responses. These data suggest that there is no defect in the JAK/STAT pathway per se in the MeWo cell line, and that the substantial resistance to interferon must be mediated through components either downstream or additional to this signalling pathway. Others have shown JAK/STAT defects to be responsible for interferon resistance in some melanoma cell lines. However, our results highlight the likely heterogeneity in the mechanisms leading to interferon resistance both in cell lines and tumours, and suggest that a clinical assay based on analysis of components of the JAK/STAT pathway may have only limited use as a predictor of interferon response.
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Affiliation(s)
- David P Jackson
- Cancer Research UK Clinical Centre, St James's University Hospital, Leeds, UK.
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132
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Kabotyanski EB, Rosen JM. Signal transduction pathways regulated by prolactin and Src result in different conformations of activated Stat5b. J Biol Chem 2003; 278:17218-27. [PMID: 12621061 DOI: 10.1074/jbc.m301578200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Stat5 is activated by a broad spectrum of cytokines, as well as non-receptor tyrosine kinases, such as Src. In this study, the DNA binding properties of the two closely related Stat5 proteins, Stat5a and Stat5b, induced either by prolactin (Prl) or by Src were analyzed by electrophoretic mobility shift assays using several different Stat5 binding sites. Src-induced Stat5b-DNA binding complexes consistently displayed a slightly faster mobility than those induced by Prl, as well as differences in their ability to be supershifted by anti-Stat5 antibodies. IP-Westerns performed using specific antibodies directed at the N and C termini of Stat5b suggested that depending on the activating stimulus, Stat5b exhibited different conformations, which influenced antibody accessibility at its C terminus. These conformational differences may in part be due to differential effects of Prl and Src on Stat5b tyrosine phosphorylation, since Src induced several additional sites of tyrosine phosphorylation of Stat5b at residues other than Tyr-699, including Tyr-724 and Tyr-679. The latter Tyr-679 is conserved in all mammalian Stat5bs, but is not present in Stat5a. A Stat 5bY679F mutant induced by Src kinase exhibited an altered pattern of nuclear localization as compared with wild-type Stat5b. Furthermore, this mutation inhibited v-Src-induced cyclin D1-luciferase reporter activity in transient transfection assays performed in Stat5a/b-deficient MEFs, suggesting that Tyr-679 phosphorylation may play a role in v-Src induced proliferation. Thus, depending on the signal transduction pathway responsible for activation, different conformations of activated Stat5 may result in selective biological responses.
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Affiliation(s)
- Elena B Kabotyanski
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030-3498, USA
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133
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Zheng S, De BP, Choudhary S, Comhair SAA, Goggans T, Slee R, Williams BRG, Pilewski J, Haque SJ, Erzurum SC. Impaired innate host defense causes susceptibility to respiratory virus infections in cystic fibrosis. Immunity 2003; 18:619-30. [PMID: 12753739 DOI: 10.1016/s1074-7613(03)00114-6] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Viral infection is the primary cause of respiratory morbidity in cystic fibrosis (CF) infants. Here, we identify that host factors allow increased virus replication and cytokine production, providing a mechanism for understanding the severity of virus disease in CF. Increased virus is due to lack of nitric oxide synthase 2 (NOS2) and 2', 5' oligoadenylate synthetase (OAS) 1 induction in response to virus or IFNgamma. This can be attributed to impairment of activation of signal transducer and activator of transcription (STAT)1, a fundamental component to antiviral defense. NO donor or NOS2 overexpression provides protection from virus infection in CF, suggesting that NO is sufficient for antiviral host defense in the human airway and is one strategy for antiviral therapy in CF children.
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Affiliation(s)
- Shuo Zheng
- Department of Pulmonary and Critical Care Medicine, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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134
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Kraus TA, Lau JF, Parisien JP, Horvath CM. A hybrid IRF9-STAT2 protein recapitulates interferon-stimulated gene expression and antiviral response. J Biol Chem 2003; 278:13033-8. [PMID: 12574168 DOI: 10.1074/jbc.m212972200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type I interferon (IFN) signaling induces the heterotrimeric transcription complex, IFN-stimulated gene factor (ISGF) 3, which contains STAT1, STAT2, and the DNA binding subunit, interferon regulatory factor (IRF) 9. Because IRF9 is targeted to the nucleus in the absence of IFN stimulation, the potential of IRF9 protein for gene regulation was examined using a GAL4 DNA binding domain fusion system. GAL4-IRF9 was transcriptionally active in reporter gene assays but not in the absence of cellular STAT1 and STAT2. However, the inert IRF9 protein was readily converted to a constitutively active ISGF3-like activator by fusion with the C-terminal transcriptional activation domain of STAT2 or the acidic activation domain of herpesvirus VP16. The IRF9 hybrids are targeted to endogenous ISGF3 target loci and can activate their transcription. Moreover, expression of the IRF9-STAT2 fusion can recapitulate the type I IFN biological response, producing a cellular antiviral state that protects cells from virus-induced cytopathic effects and inhibits virus replication. The antiviral state generated by regulated IRF9-STAT2 hybrid protein expression is independent of autocrine IFN signaling and inhibits both RNA and DNA viruses.
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Affiliation(s)
- Thomas A Kraus
- Immunobiology Center, The Mount Sinai School of Medicine, New York, New York 10029, USA
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135
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Pilz A, Ramsauer K, Heidari H, Leitges M, Kovarik P, Decker T. Phosphorylation of the Stat1 transactivating domain is required for the response to type I interferons. EMBO Rep 2003; 4:368-73. [PMID: 12671680 PMCID: PMC1319158 DOI: 10.1038/sj.embor.embor802] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2002] [Revised: 01/21/2003] [Accepted: 02/04/2003] [Indexed: 11/08/2022] Open
Abstract
Stat1 (signal transducer and activator of transcription 1) regulates transcription in response to the type I interferons IFN-alpha and IFN-beta, either in its dimerized form or as a subunit of the interferon-stimulated gene factor 3 (Isgf3) complex (consisting of Stat1, Stat2 and interferon-regulating factor 9). Full-length Stat1-alpha and the splice variant Stat1-beta, which lacks the carboxyl terminus and the Ser727 phosphorylation site, are found in all cell types. IFN-induced phosphorylation of Stat1-alpha on Ser727 occurs in the absence of the candidate kinase, protein kinase C-delta. When expressed in Stat1-deficient cells, Stat1-beta and a Stat1-S727A mutant both restored the formation of Stat1 dimers and of the Isgf3 complex on treatment with IFN-beta. By contrast, only Stat1-alpha restored the ability of IFN-beta to induce high levels of transcription from target genes of Stat1 dimers and Isgf3 and to induce an antiviral state. Our data suggest an important contribution of the Stat1 C terminus and its phosphorylation at Ser727 to the transcriptional activities of the Stat1 dimer and the Isgf3 complex.
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Affiliation(s)
- Andreas Pilz
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
- These authors contributed equally to this work
| | - Katrin Ramsauer
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
- These authors contributed equally to this work
| | - Hamid Heidari
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Michael Leitges
- Max Planck Institute of Experimental Endocrinology, Feodor-Lynenstrasse 7, D-30625 Hannover, Germany
| | - Pavel Kovarik
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Thomas Decker
- Institute of Microbiology and Genetics, Vienna Biocenter, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
- Tel: +43 1 4277 54605; Fax: +43 1 4277 9546;
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136
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Dupuis S, Jouanguy E, Al-Hajjar S, Fieschi C, Al-Mohsen IZ, Al-Jumaah S, Yang K, Chapgier A, Eidenschenk C, Eid P, Al Ghonaium A, Tufenkeji H, Frayha H, Al-Gazlan S, Al-Rayes H, Schreiber RD, Gresser I, Casanova JL. Impaired response to interferon-alpha/beta and lethal viral disease in human STAT1 deficiency. Nat Genet 2003; 33:388-91. [PMID: 12590259 DOI: 10.1038/ng1097] [Citation(s) in RCA: 599] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2002] [Accepted: 01/08/2003] [Indexed: 12/14/2022]
Abstract
The receptors for interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma activate components of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, leading to the formation of at least two transcription factor complexes. STAT1 interacts with STAT2 and p48/IRF-9 to form the transcription factor IFN-stimulated gene factor 3 (ISGF3). STAT1 dimers form gamma-activated factor (GAF). ISGF3 is induced mainly by IFN-alpha/beta, and GAF by IFN-gamma, although both factors can be activated by both types of IFN. Individuals with mutations in either chain of the IFN-gamma receptor (IFN-gammaR) are susceptible to infection with mycobacteria. A heterozygous STAT1 mutation that impairs GAF but not ISGF3 activation has been found in other individuals with mycobacterial disease. No individuals with deleterious mutations in the IFN-alpha/beta signaling pathway have been described. We report here two unrelated infants homozygous with respect to mutated STAT1 alleles. Neither IFN-alpha/beta nor IFN-gamma activated STAT1-containing transcription factors. Like individuals with IFN-gammaR deficiency, both infants suffered from mycobacterial disease, but unlike individuals with IFN-gammaR deficiency, both died of viral disease. Viral multiplication was not inhibited by recombinant IFN-alpha/beta in cell lines from the two individuals. Inherited impairment of the STAT1-dependent response to human IFN-alpha/beta thus results in susceptibility to viral disease.
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Affiliation(s)
- Stéphanie Dupuis
- Laboratoire de Génétique Humaine des Maladies Infectieuses, Université de Paris René Descartes-INSERM UMR550, Faculté de Médecine Necker-Enfants Malades, 75015 Paris, France
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137
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Ruvolo V, Navarro L, Sample CE, David M, Sung S, Swaminathan S. The Epstein-Barr virus SM protein induces STAT1 and interferon-stimulated gene expression. J Virol 2003; 77:3690-701. [PMID: 12610144 PMCID: PMC149524 DOI: 10.1128/jvi.77.6.3690-3701.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viruses utilize numerous mechanisms to counteract the host's immune response. Interferon production is a major component of the host antiviral response. Many viruses, therefore, produce proteins or RNA molecules that inhibit interferon-induced signal transduction pathways and their associated antiviral effects. Surprisingly, some viruses directly induce expression of interferon-induced genes. SM, an early lytic Epstein-Barr virus (EBV) nuclear protein, was found to specifically increase the expression of several genes (interferon-stimulated genes) that are known to be strongly induced by alpha/beta interferons. SM does not directly stimulate alpha/beta interferon secretion but instead induces STAT1, an intermediate step in the interferon signaling pathway. SM is a posttranscriptional activator of gene expression and increases STAT1 mRNA accumulation, particularly that of the functionally distinct STAT1beta splice variant. SM expression in B lymphocytes is associated with decreased cell proliferation but does not decrease cell viability or induce cell cycle arrest. These results indicate that EBV can specifically induce cellular genes that are normally physiological targets of interferon by inducing components of cytokine signaling pathways. Our findings therefore suggest that some aspects of the interferon response may be positively modulated by infecting viruses.
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Affiliation(s)
- Vivian Ruvolo
- University of Florida Shands Cancer Center, University of Florida, Gainesville, Florida 32610-0232, USA
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138
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Garcin D, Marq JB, Goodbourn S, Kolakofsky D. The amino-terminal extensions of the longer Sendai virus C proteins modulate pY701-Stat1 and bulk Stat1 levels independently of interferon signaling. J Virol 2003; 77:2321-9. [PMID: 12551969 PMCID: PMC141115 DOI: 10.1128/jvi.77.4.2321-2329.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Sendai virus (SeV) C proteins are known to interact with Stat1 to prevent interferon (IFN)-induced pY701-Stat1 formation and IFN signaling. Nevertheless, pY701-Stat1 levels paradoxically increase during SeV infection. The C proteins also induce bulk Stat1 instability in some cells, similar to rubulavirus V proteins. We have found that SeV infection increases pY701-Stat1 levels even in cells in which bulk Stat1 levels strongly decrease. Remarkably, both the decrease in bulk Stat1 levels and the increase in pY701-Stat1 levels were found to be independent of the IFN signaling system, i.e., these events occur in mutant cells in which various components of the IFN signaling system have been disabled. Consistent with this, the C-induced decrease in Stat1 levels does not require Y701 of Stat1. We present evidence that C interacts with Stat1 in two different ways, one that prevents IFN-induced pY701-Stat1 formation and IFN signaling that has already been documented, and another that induces pY701-Stat1 formation (while decreasing bulk Stat1 levels) in a manner that does not require IFN signaling. These two types of Stat1 interaction are also distinguishable by C gene mutations. In particular, the IFN signaling-independent Stat1 interactions specifically require the amino-terminal extensions of the longer C proteins. The actions of the SeV C proteins in counteracting the cellular antiviral response are clearly more extensive than previously appreciated.
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Affiliation(s)
- Dominique Garcin
- Department of Genetics and Microbiology, University of Geneva School of Medicine, Centre Médicale Universitaire, 9 Avenue de Champel, CH-1211 Geneva, Switzerland
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139
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Ding Y, Chen D, Tarcsafalvi A, Su R, Qin L, Bromberg JS. Suppressor of cytokine signaling 1 inhibits IL-10-mediated immune responses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:1383-91. [PMID: 12538698 DOI: 10.4049/jimmunol.170.3.1383] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IL-10 has proved to be a key cytokine in regulating inflammatory responses by controlling the production and function of various other cytokines. The suppressor of cytokine signaling (SOCS) gene products are a family of cytoplasmic molecules that are essential mediators for negatively regulating cytokine signaling. It has been previously shown that IL-10 induced SOCS3 expression and that forced constitutive expression of SOCS3 inhibits IL-10/STAT3 activation and LPS-induced macrophage activation. In this report, we show that, in addition to SOCS3 expression, IL-10 induces SOCS1 up-regulation in all cell lines tested, including Ba/F3 pro-B cells, MC/9 mast cells, M1 leukemia cells, U3A human fibroblasts, and primary mouse CD4(+) T cells. Induction of SOCS molecules is dependent on STAT3 activation by IL-10R1. Cell lines constitutively overexpressing SOCS proteins demonstrated that SOCS1 and SOCS3, but not SOCS2, are able to partially inhibit IL-10-mediated STAT3 activation and proliferative responses. Pretreatment of M1 cells with IFN-gamma resulted in SOCS1 induction and a reduction of IL-10-mediated STAT3 activation and cell growth inhibition. IL-10-induced SOCS is associated with the inhibition of IFN-gamma signaling in various cell types, and this inhibition is independent of C-terminal serine residues of the IL-10R, previously shown to be required for other anti-inflammatory responses. Thus, the present results show that both SOCS1 and SOCS3 are induced by IL-10 and may be important inhibitors of both IL-10 and IFN-gamma signaling. IL-10-induced SOCS1 may directly inhibit IL-10 IFN-gamma signaling, while inhibition of other proinflammatory cytokine responses may use additional IL-10R1-mediated mechanisms.
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Affiliation(s)
- Yaozhong Ding
- Carl C. Icahn Institute for Gene Therapy and Molecular Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA
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140
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Lau JF, Nusinzon I, Burakov D, Freedman LP, Horvath CM. Role of metazoan mediator proteins in interferon-responsive transcription. Mol Cell Biol 2003; 23:620-8. [PMID: 12509459 PMCID: PMC151539 DOI: 10.1128/mcb.23.2.620-628.2003] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The interferon (IFN)-induced signal transduction and transcription activation complex, ISGF3, is assembled from three proteins, STAT1, STAT2, and IRF9. Of these components, STAT2 provides a fundamental and essential transcriptional activation function for ISGF3. In the present study, we show that ISGF3-mediated transcription is dependent on STAT2 interactions with DRIP150, a subunit of the multimeric Mediator coactivator complex. Other Mediator subunits, DRIP77 and DRIP130, were found either to bind STAT2 without augmenting ISGF3 transcriptional activity or to enhance ISGF3 transcription without binding STAT2, but only DRIP150 both enhanced IFN-dependent transcription and coimmunoprecipitated with STAT2. Endogenous DRIP150 and STAT2 were able to interact in solution, and DNA affinity chromatography and chromatin immunoprecipitation assays demonstrated that DRIP150 binds to the mature, activated ISGF3-DNA complex and is recruited to target gene promoters in an IFN-dependent fashion. IFN-dependent recruitment of DRIP130 to an ISGF3 target promoter and SRB10-STAT2 coprecipitation suggest indirect association with a multisubunit Mediator complex. The site of STAT2 interaction was mapped to DRIP150 residues 188 to 566, which are necessary and sufficient for interaction with STAT2. Expression of this DRIP150 fragment, but not DRIP150 fragments outside the STAT2 interaction region, suppressed ISGF3-mediated transcriptional activity in a dominant-negative fashion, suggesting a direct functional role of this domain in mediating STAT2-DRIP150 interactions. These findings indicate that the IFN-activated ISGF3 transcription factor regulates transcription through contact with DRIP150 and implicate the Mediator coactivator complex in IFN-activated gene regulation.
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Affiliation(s)
- Joe F Lau
- Immunobiology Center, The Mount Sinai School of Medicine, New York, New York 10029, USA
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141
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Schlaak JF, Hilkens CMU, Costa-Pereira AP, Strobl B, Aberger F, Frischauf AM, Kerr IM. Cell-type and donor-specific transcriptional responses to interferon-alpha. Use of customized gene arrays. J Biol Chem 2002; 277:49428-37. [PMID: 12386168 DOI: 10.1074/jbc.m205571200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A sensitive, specific, reproducible, robust, and cost-effective customized cDNA array system based on established nylon membrane technology has been developed for convenient multisample expression profiling for several hundred genes of choice. The genes represented are easily adjusted (depending on the availability of corresponding cDNAs) and the method is accordingly readily applicable to a wide variety of systems. Here we have focused on the expression profiles for interferon-alpha2a, the most widely used interferon for the treatment of viral hepatitis and malignancies, in primary cells (peripheral blood mononuclear cells, T cells, and dendritic cells) and cell lines (Kit255, HT1080, HepG2, and HuH7). Of 150 genes studied, only six were consistently induced in all cell types and donors, whereas 74 genes were induced in at least one cell type. IRF-7 was identified as the only gene exclusively induced in the hematopoietic cells. No gene was exclusively induced in the nonhematopoietic cell lines. In T cells 12, and in dendritic cells, 25 genes were induced in all donors whereas 45 and 42 genes, respectively, were induced in at least one donor. The data suggest that signaling through IFN-alpha2 can be substantially modulated to yield significant cell-type and donor-specific qualitative and quantitative differences in gene expression in response to this cytokine under highly standardized conditions.
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Affiliation(s)
- Joerg F Schlaak
- Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
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142
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Le MN, Kohanski RA, Wang LH, Sadowski HB. Dual mechanism of signal transducer and activator of transcription 5 activation by the insulin receptor. Mol Endocrinol 2002; 16:2764-79. [PMID: 12456798 DOI: 10.1210/me.2002-0017] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Insulin stimulates signal transducer and activator of transcription 5 (Stat5) activation in insulin receptor (IR)-overexpressing cell lines and in insulin target tissues of mice. Stat5b and insulin receptor substrate 1 (IRS-1) interact with the same autophosphorylation site in the IR [phosphotyrosine (pY) 972] in yeast two-hybrid assays, and the IR phosphorylates Stat5b in vitro. These data suggest that Stat5 proteins might be recruited to, and phosphorylated by, the activated IR in vivo. Nevertheless, insulin activates Janus kinases (JAKs) in IR-overexpressing cell lines and in insulin target tissues. To determine whether Stat5 proteins must be recruited to the pY972LSA motif in the IR for insulin-stimulated activation in mammalian cells, we generated and tested a series of IR mutants. The L973R/A975D mutation abolishes the ability of the IR to induce Stat5 activation, whereas IRS-1 phosphorylation is unaffected. In contrast, the N969A/P970A mutation in the IR has no effect on Stat5 activation but significantly reduces IRS-1 phosphorylation. In coimmunoprecipitation assays, insulin-stimulated Stat5 activation correlates with Stat5 recruitment to the IR. We also find that insulin stimulates tyrosine phosphorylation of JAKs that are constitutively associated with the IR. Expression of dominant-negative (DN) JAKs, the JAK inhibitor suppressor of cytokine signaling 1, or pretreatment with the JAK inhibitor, AG490, reduces, but does not eliminate, insulin-induced Stat5 activation. Expression of the appropriate pair of DN JAKs in each of the singly JAK-deficient cell lines further establishes a component of insulin-stimulated Stat5 activation that is JAK independent. This likely represents phosphorylation of Stat5 proteins by the IR, as we find that IR kinase domain phosphorylates Stat5b in vitro on Y699 as efficiently as JAK2. Increasing the concentration of Stat5 proteins in cells favors the direct phosphorylation of Stat5 by the IR kinase where the DN-JAK inhibition of insulin-stimulated Stat5 activation becomes insignificant. At physiological levels of Stat5 however, we propose that JAKs and the IR both contribute to the insulin-induced phosphorylation of Stat5.
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Affiliation(s)
- Maithao N Le
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY 10029, USA
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143
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Gotoh B, Komatsu T, Takeuchi K, Yokoo J. Paramyxovirus strategies for evading the interferon response. Rev Med Virol 2002; 12:337-57. [PMID: 12410527 DOI: 10.1002/rmv.357] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Two genera, the Respirovirus (Sendai virus (SeV) and human parainfluenza virus (hPIV3) and the Rubulavirus (simian virus (SV) 5, SV41, mumps virus and hPIV2), of the three in the subfamily Paramyxovirinae inhibit interferon (IFN) signalling to circumvent the IFN response. The viral protein responsible for the inhibition is the C protein for respirovirus SeV and the V protein for the rubulaviruses, both of which are multifunctional accessory proteins expressed from the P gene. SeV suppresses IFN-stimulated tyrosine phosphorylation of signal transducers and activators of transcription (STATs) at an early phase of infection and further inhibits the downstream signalling without degrading any of the signalling components in most cell lines. On the contrary, the Rubulavirus V protein targets Stat1 or Stat2 for degradation. Proteasome-mediated degradation appears to be involved in most cases. Studies on the molecular mechanisms by which paramyxoviruses evade the IFN response will offer important information for modulating the JAK-STAT pathway, designing novel antiviral drugs and recombinant live vaccines, and improving paramyxovirus expression vectors for gene therapy.
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Affiliation(s)
- Bin Gotoh
- Department of Microbiology, Fukui Medical University School of Medicine, Shimoaizuki 23-3, Matsuoka-cho, Yoshida-gun, Fukui 910-1193, Japan.
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144
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Henriksen MA, Betz A, Fuccillo MV, Darnell JE. Negative regulation of STAT92E by an N-terminally truncated STAT protein derived from an alternative promoter site. Genes Dev 2002; 16:2379-89. [PMID: 12231627 PMCID: PMC187436 DOI: 10.1101/gad.1020702] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2002] [Accepted: 07/18/2002] [Indexed: 11/25/2022]
Abstract
Previously unrecognized mRNAs originating from a dual promoter at the stat92E locus are described. One of these encodes a truncated protein, DeltaNSTAT92E, that lacks the N-terminal 133 amino acids. Antibodies detect both the full-length and truncated molecules early in embryogenesis (1-5 h), and mRNA detection by specific RT-PCR reactions accords with the protein distribution. Given that the N termini of mammalian STATs are known to have positive functions in transcriptional activation, we explored the role of DeltaNSTAT92E early in embryogenesis. By increasing the DeltaNSTAT92E-to-STAT92E ratio in overexpression and RNAi experiments, we observe phenotypes compatible with suppression of wild-type STAT92E activity. We therefore conclude that the short form of STAT92E is a naturally occurring dominant-negative product that can be added to the growing list of negative regulators of STAT activity.
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Affiliation(s)
- Melissa A Henriksen
- Laboratory of Molecular Cell Biology, The Rockefeller University, New York, New York 10021, USA
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145
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Lejeune D, Dumoutier L, Constantinescu S, Kruijer W, Schuringa JJ, Renauld JC. Interleukin-22 (IL-22) activates the JAK/STAT, ERK, JNK, and p38 MAP kinase pathways in a rat hepatoma cell line. Pathways that are shared with and distinct from IL-10. J Biol Chem 2002; 277:33676-82. [PMID: 12087100 DOI: 10.1074/jbc.m204204200] [Citation(s) in RCA: 377] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
IL (interleukin)-22 is an IL-10-related cytokine; its main biological activity known thus far is the induction of acute phase reactants in liver and pancreas. IL-22 signals through a receptor that is composed of two chains from the class II cytokine receptor family: IL-22R (also called ZcytoR11/CRF2-9) and IL-10Rbeta (CRF2-4), which is also involved in IL-10 signaling. In this report, we analyzed the signal transduction pathways activated in response to IL-22 in a rat hepatoma cell line, H4IIE. We found that IL-22 induces activation of JAK1 and Tyk2 but not JAK2, as well as phosphorylation of STAT1, STAT3, and STAT5 on tyrosine residues, extending the similarities between IL-22 and IL-10. However our results unraveled some differences between IL-22 and IL-10 signaling. Using antibodies specific for the phosphorylated form of MEK1/2, ERK1/2, p90RSK, JNK, and p38 kinase, we showed that IL-22 activates the three major MAPK pathways. IL-22 also induced serine phosphorylation of STAT3 on Ser(727). This effect, which is not shared with IL-10, was only marginally affected by MEK1/2 inhibitors, indicating that other pathways might be involved. Finally, by overexpressing a STAT3 S727A mutant, we showed that serine phosphorylation is required to achieve maximum transactivation of a STAT responsive promoter upon IL-22 stimulation.
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Affiliation(s)
- Diane Lejeune
- Ludwig Institute for Cancer Research, Brussels Branch, Experimental Medicine Unit, Université de Louvain, avenue Hippocrate 74, B-1200 Brussels, Belgium
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146
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Costa-Pereira AP, Williams TM, Strobl B, Watling D, Briscoe J, Kerr IM. The antiviral response to gamma interferon. J Virol 2002; 76:9060-8. [PMID: 12186889 PMCID: PMC136459 DOI: 10.1128/jvi.76.18.9060-9068.2002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
A role for alpha/beta interferon (IFN-alpha/beta) in the IFN-gamma antiviral response has long been suggested. Accordingly, possible roles for autocrine or double-stranded-RNA (dsRNA)-induced IFN-alpha/beta in the IFN-gamma response were investigated. Use was made of wild-type and a variety of mutant human fibrosarcoma cell lines, including mutant U5A cells, which lack a functional IFN-alpha/beta receptor and hence an IFN-alpha/beta response. IFN-gamma did not induce detectable levels of IFN-alpha/beta in any of the cell lines, nor was the IFN-gamma response per se dependent on autocrine IFN-alpha/beta. On the other hand, a number of responses to dsRNA [poly(I). poly(C)] and encephalomyocarditis virus were greatly enhanced by IFN-gamma pretreatment (priming) of wild-type cells or of mutant cells lacking an IFN-alpha/beta response; these include the primary induction of dsRNA-inducible mRNAs, including IFN-beta mRNA, and, to a lesser extent, the dsRNA-mediated activation of the p38 mitogen-activated protein (MAP) kinase(s). IFN-gamma priming of mRNA induction by dsRNA is dependent on JAK1 and shows biphasic kinetics, with an initial rapid (<30-min) response being followed by a more substantial effect on overnight incubation. The IFN-gamma-primed dsRNA responses appear to be subject to modulation through the p38, phosphatidylinositol 3-kinase, and ERK1/ERK2 MAP kinase pathways. It can be concluded that despite efficient priming of IFN-beta production, the IFN-alpha/beta pathways play no significant role in the primary IFN-gamma antiviral response in these cell-virus systems. The observed IFN-gamma priming of dsRNA responses, on the other hand, will likely play a significant role in combating virus infection in vivo.
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Affiliation(s)
- Ana P Costa-Pereira
- Cancer Research UK London Research Institute, London WC2A 3PX, United Kingdom
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147
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Aittomäki S, Yang J, Scott EW, Simon MC, Silvennoinen O. Distinct functions for signal transducer and activator of transcription 1 and PU.1 in transcriptional activation of Fc gamma receptor I promoter. Blood 2002; 100:1078-80. [PMID: 12130529 DOI: 10.1182/blood-2001-12-0236] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The myeloid cell-specific expression and interferon-gamma (IFN-gamma) induction of Fc gamma receptor I (FcgammaRI) requires cooperation between PU.1 and signal transducer and activator of transcription 1 (Stat1) by means of mechanisms that are unknown. We found that PU.1 and Stat1 mediated distinct functions in the activation of FcgammaRI promoter. The basal activity of the natural FcgammaRI promoter was strictly dependent on PU.1, and IFN-gamma induction required both PU.1 and Stat1. Recruitment of TATA-binding protein (TBP) to the FcgammaRI promoter did not replace PU.1 in promoter activation, suggesting that TBP is not sufficient for FcgammaRI activation and that PU.1 mediates additional contacts with basal transcription machinery. In contrast, Stat1 did not interact with basal transcription machinery, but the Stat1-mediated activation of FcgammaRI promoter critically required CREB-binding protein (CBP)/p300. These results define functional cooperativity between PU.1 and Stat1 in FcgammaRI promoter activation, in which PU.1 appears to serve as a bridging factor with the basal transcription machinery and IFN-gamma-mediated induction of transcription occurs through recruitment of CBP/p300 by Stat1.
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Affiliation(s)
- Saara Aittomäki
- Institute of Medical Technology, University of Tampere, Finland
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148
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Abstract
A new role of the Paramyxovirus accessory proteins has been uncovered. The P gene of the subfamily Paramyxovirinae encodes accessory proteins including the V and/or C protein by means of pseudotemplated nucleotide addition (RNA editing) or by overlapping open reading frame. The Respirovirus (Sendai virus and human parainfluenza virus (hPIV)3) and Rubulavirus (simian virus (SV)5, SV41, mumps virus and hPIV2) circumvent the interferon (IFN) response by inhibiting IFN signaling. The responsible genes were mapped to the C gene for SeV and the V gene for rubulaviruses. On the other hand, wild type measles viruses isolated from clinical specimens suppress production of IFN, although responsible viral factors remain to be identified. Both human and bovine respiratory syncytial viruses (RSVs) counteract the antiviral effect of IFN with inhibiting neither IFN signaling nor IFN production. Bovine RSV NS1 and NS2 proteins cooperatively antagonize the antiviral effect of IFN. Studies on the molecular mechanism by which viruses circumvent the host IFN response will not only illustrate co-evolution of virus strategies of immune evasion but also provide basic information useful for engineering novel antiviral drugs as well as recombinant live vaccine.
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Affiliation(s)
- B Gotoh
- Department of Microbiology, Fukui Medical University, Japan.
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149
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Parisien JP, Lau JF, Horvath CM. STAT2 acts as a host range determinant for species-specific paramyxovirus interferon antagonism and simian virus 5 replication. J Virol 2002; 76:6435-41. [PMID: 12050355 PMCID: PMC136248 DOI: 10.1128/jvi.76.13.6435-6441.2002] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The antiviral state induced by alpha/beta interferon (IFN-alpha/beta) is a powerful selective pressure for virus evolution of evasive strategies. The paramyxoviruses simian virus 5 (SV5) and human parainfluenza virus 2 (HPIV2) overcome IFN-alpha/beta responses through the actions of their V proteins, which induce proteasomal degradation of cellular IFN-alpha/beta-activated signal transducers and activators of transcription STAT1 and STAT2. SV5 infection induces STAT1 degradation and IFN-alpha/beta inhibition efficiently in human cells but not in mouse cells, effectively restricting SV5 host range. Here, the cellular basis for this species specificity is demonstrated to result from differences between human and murine STAT2. Expression in mouse cells of full-length or truncated human STAT2 cDNA is sufficient to permit antagonism of endogenous murine IFN-alpha/beta signaling by SV5 and HPIV2 V proteins. Furthermore, virus-induced STAT protein degradation is observed in mouse cells only in the presence of ectopically expressed human STAT2. The results indicate that STAT2 acts as an intracellular determinant of paramyxovirus host range restriction, which contributes to the species specificity of virus replication, and that human STAT2 can confer a growth advantage for SV5 in the murine host.
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Affiliation(s)
- Jean-Patrick Parisien
- Immunobiology Center, The Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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Mukhopadhyay A, Shishodia S, Fu XY, Aggarwal BB. Lack of requirement of STAT1 for activation of nuclear factor-kappaB, c-Jun NH2-terminal protein kinase, and apoptosis by tumor necrosis factor-alpha. J Cell Biochem 2002; 84:803-15. [PMID: 11835405 DOI: 10.1002/jcb.10097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Tumor necrosis factor (TNF) is one of the most potent activators of nuclear transcription factor NF-kappaB, c-Jun N-terminal protein kinase (JNK), and apoptosis in a wide variety of cells. The biological effects of TNF are mediated through sequential interactions of various cytoplasmic proteins with intracellular domains of TNF receptors. Whether signal transducer and activator of transcription-1 (STAT1), which mediates interferon (IFN) signaling, also plays any role in the TNF-mediated activation of NF-kappaB, JNK, and apoptosis has not been established. Here, we report our investigation of the role of STAT1 in TNF signaling using STAT1-deficient U3A and STAT1-stably transfected U3A-PSG91 cells. IFNalpha inhibited the proliferation of STAT1-expressing U3A-PSG91 cells but had no effect on STAT1-negative U3A cells. TNF alone, even up to 10 nM, had no effect on the proliferation of either U3A-PSG91 or U3A cells. Irrespective of STAT1 status, TNF induced cytotoxic effects in the presence of cycloheximide (CHX) in both cell types. Additionally, TNF-induced caspase-3 and caspase-8 activation and TNF-induced PARP cleavage were unaffected by the presence or absence of STAT1. TNF activated NF-kappaB, consisting of p50 and p65, in both U3A and U3A-pSG91 cells in a dose- and time-dependent manner, but the degree and rate of activation were slightly lower in U3A cells, as were IkappaBalpha degradation and NF-kappaB-dependent reporter gene expression. STAT1 was, however, required for IFNalpha-mediated downregulation of TNF-induced NF-kappaB activation. TNF activated JNK in both cell types, but dose and time of exposure required for optimum activation differed slightly. Thus, overall our results indicate that STAT1 plays a minimal role in TNF-mediated cellular responses.
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Affiliation(s)
- Asok Mukhopadhyay
- Cytokine Research Section, Department of Bioimmunotherapy, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030-4009, USA
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