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Swaraj S, Tripathi S. Interference without interferon: interferon-independent induction of interferon-stimulated genes and its role in cellular innate immunity. mBio 2024:e0258224. [PMID: 39302126 DOI: 10.1128/mbio.02582-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2024] Open
Abstract
Interferons (IFNs) are multifaceted proteins that play pivotal roles in orchestrating robust antiviral immune responses and modulating the intricate landscape of host immunity. The major signaling pathway activated by IFNs is the JAK/STAT (Janus kinase/signal transducer and activator of transcription) pathway, which leads to the transcription of a battery of genes, collectively known as IFN-stimulated genes (ISGs). While the well-established role of IFNs in coordinating the innate immune response against viral infections is widely acknowledged, recent years have provided a more distinct comprehension of the functional significance attributed to non-canonical, IFN-independent induction of ISGs. In this review, we summarize the non-conventional signaling pathways of ISG induction. These alternative pathways offer new avenues for developing antiviral strategies or immunomodulation in various diseases.
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Affiliation(s)
- Shachee Swaraj
- Emerging Viral Pathogens Laboratory, Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru, India
- Microbiology & Cell Biology Department, Biological Sciences Division, Indian Institute of Science, Bengaluru, India
| | - Shashank Tripathi
- Emerging Viral Pathogens Laboratory, Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru, India
- Microbiology & Cell Biology Department, Biological Sciences Division, Indian Institute of Science, Bengaluru, India
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2
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Shuster M, Lyu Z, Augenstreich J, Mathur S, Ganesh A, Ling J, Briken V. Salmonella Typhimurium infection inhibits macrophage IFNβ signaling in a TLR4-dependent manner. Infect Immun 2024:e0009824. [PMID: 39269166 DOI: 10.1128/iai.00098-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 08/16/2024] [Indexed: 09/15/2024] Open
Abstract
Type I Interferons (IFNs) generally have a protective role during viral infections, but their function during bacterial infections is dependent on the bacterial species. Legionella pneumophila, Shigella sonnei and Mycobacterium tuberculosis can inhibit type I IFN signaling. Here we examined the role of type I IFN, specifically IFNβ, in the context of Salmonella enterica serovar Typhimurium (STm) macrophage infections and the capacity of STm to inhibit type I IFN signaling. We demonstrate that IFNβ has no effect on the intracellular growth of STm in infected bone marrow derived macrophages (BMDMs) derived from C57BL/6 mice. STm infection inhibits IFNβ signaling but not IFNγ signaling in a murine macrophage cell line. We show that this inhibition is independent of the type III and type VI secretion systems expressed by STm and is also independent of bacterial phagocytosis. The inhibition is Toll-like receptor 4 (TLR4)-dependent as the TLR4 ligand, lipopolysaccharide (LPS), alone is sufficient to inhibit IFNβ-mediated signaling. Cells downregulated their surface levels of IFNα/β receptor 1 (IFNAR1) in response to LPS, which may be mediating our observed inhibition. Lastly, we examined this inhibition in the context of TLR4-deficient BMDMs as well as TLR4 RNA interference and we observed a loss of inhibition with LPS stimulation as well as STm infection. In summary, we show that macrophages exposed to STm have reduced IFNβ signaling via crosstalk with TLR4 signaling, which may be mediated by reduced host cell surface IFNAR1, and that IFNβ signaling does not affect cell-autonomous host defense against STm.
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Affiliation(s)
- Michael Shuster
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Zhihui Lyu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Jacques Augenstreich
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Shrestha Mathur
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Akshaya Ganesh
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Jiqiang Ling
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Volker Briken
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
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3
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Shuster M, Lyu Z, Augenstreich J, Mathur S, Ganesh A, Ling J, Briken V. Salmonella Typhimurium infection inhibits macrophage IFNβ signaling in a TLR4-dependent manner. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.05.583530. [PMID: 38496427 PMCID: PMC10942315 DOI: 10.1101/2024.03.05.583530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Type I Interferons (IFNs) generally have a protective role during viral infections, but their function during bacterial infections is dependent on the bacterial species. Legionella pneumophila, Shigella sonnei and Mycobacterium tuberculosis can inhibit type I IFN signaling. Here we examined the role of type I IFN, specifically IFNβ, in the context of Salmonella enterica serovar Typhimurium (STm) macrophage infections and the capacity of STm to inhibit type I IFN signaling. We demonstrate that IFNβ has no effect on the intracellular growth of STm in infected bone marrow derived macrophages (BMDMs) derived from C57BL/6 mice. STm infection inhibits IFNβ signaling but not IFNγ signaling in a murine macrophage cell line. We show that this inhibition is independent of the type III and type VI secretion systems expressed by STm and is also independent of bacterial phagocytosis. The inhibition is Toll-like receptor 4 (TLR4)-dependent as the TLR4 ligand, lipopolysaccharide (LPS), alone is sufficient to inhibit IFNβ-mediated signaling and STm-infected, TLR4-deficient BMDMs do not exhibit inhibited IFNβ signaling. In summary, we show that macrophages exposed to STm have reduced IFNβ signaling via crosstalk with TLR4 signaling, and that IFNβ signaling does not affect cell autonomous host defense against STm.
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Affiliation(s)
- Michael Shuster
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Zhihui Lyu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Jacques Augenstreich
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Shrestha Mathur
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Akshaya Ganesh
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Jiqiang Ling
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Volker Briken
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
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4
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Roy A, Srivastava M, Saqib U, Liu D, Faisal SM, Sugathan S, Bishnoi S, Baig MS. Potential therapeutic targets for inflammation in toll-like receptor 4 (TLR4)-mediated signaling pathways. Int Immunopharmacol 2016; 40:79-89. [PMID: 27584057 DOI: 10.1016/j.intimp.2016.08.026] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/08/2016] [Accepted: 08/23/2016] [Indexed: 12/13/2022]
Abstract
Inflammation is set off when innate immune cells detect infection or tissue injury. Tight control of the severity, duration, and location of inflammation is an absolute requirement for an appropriate balance between clearance of injured tissue and pathogens versus damage to host cells. Impeding the risk associated with the imbalance in the inflammatory response requires precise identification of potential therapeutic targets involved in provoking the inflammation. Toll-like receptors (TLRs) primarily known for the pathogen recognition and subsequent immune responses are being investigated for their pathogenic role in various chronic diseases. A mammalian homologue of Drosophila Toll receptor 4 (TLR4) was shown to induce the expression of genes involved in inflammatory responses. Signaling pathways via TLR4 activate various transcription factors like Nuclear factor kappa-light-chain-enhancer (NF-κB), activator protein 1 (AP1), Signal Transducers and Activators of Transcription family of transcription factors (STAT1) and Interferon regulatory factors (IRF's), which are the key players regulating the inflammatory response. Inhibition of these targets and their upstream signaling molecules provides a potential therapeutic approach to treat inflammatory diseases. Here we review the therapeutic targets involved in TLR-4 signaling pathways that are critical for suppressing chronic inflammatory disorders.
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Affiliation(s)
- Anjali Roy
- Center for Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology (IIT), Indore, MP, India
| | - Mansi Srivastava
- Center for Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology (IIT), Indore, MP, India
| | - Uzma Saqib
- Discipline of Chemistry, School of Basic Sciences, Indian Institute of Technology Indore (IITI), Indore, MP, India
| | - Dongfang Liu
- Center for Inflammation & Epigenetics, Houston Methodist Research Institute, Houston, TX, USA
| | - Syed M Faisal
- National Institute of Animal Biotechnology (NIAB), Hyderabad, Telangana, India
| | - Subi Sugathan
- Center for Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology (IIT), Indore, MP, India
| | - Suman Bishnoi
- Center for Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology (IIT), Indore, MP, India
| | - Mirza S Baig
- Center for Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology (IIT), Indore, MP, India.
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5
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PPP1, a plant-specific regulator of transcription controls Arabidopsis development and PIN expression. Sci Rep 2016; 6:32196. [PMID: 27553690 PMCID: PMC4995536 DOI: 10.1038/srep32196] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 08/04/2016] [Indexed: 01/31/2023] Open
Abstract
Directional transport of auxin is essential for plant development, with PIN auxin transport proteins representing an integral part of the machinery that controls hormone distribution. However, unlike the rapidly emerging framework of molecular determinants regulating PIN protein abundance and subcellular localization, insights into mechanisms controlling PIN transcription are still limited. Here we describe PIN2 PROMOTER BINDING PROTEIN 1 (PPP1), an evolutionary conserved plant-specific DNA binding protein that acts on transcription of PIN genes. Consistent with PPP1 DNA-binding activity, PPP1 reporter proteins are nuclear localized and analysis of PPP1 null alleles and knockdown lines indicated a function as a positive regulator of PIN expression. Furthermore, we show that ppp1 pleiotropic mutant phenotypes are partially reverted by PIN overexpression, and results are presented that underline a role of PPP1-PIN promoter interaction in PIN expression control. Collectively, our findings identify an elementary, thus far unknown, plant-specific DNA-binding protein required for post-embryonic plant development, in general, and correct expression of PIN genes, in particular.
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6
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Cheriyath V, Leaman DW, Borden EC. Emerging roles of FAM14 family members (G1P3/ISG 6-16 and ISG12/IFI27) in innate immunity and cancer. J Interferon Cytokine Res 2010; 31:173-81. [PMID: 20939681 DOI: 10.1089/jir.2010.0105] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Interferons (IFNs) manifest their cellular functions by regulating expression of target genes known collectively as IFN-stimulated genes (ISGs). The repertoires of ISGs vary slightly between cell types, but routinely include a core of common ISGs robustly upregulated in most IFN-treated cells. Here, we review the regulation and cellular functions of 2 related ISGs, ISG12 (IFI27) and G1P3 (ISG 6-16), that are commonly induced by IFNs in most, if not all, IFN-responsive cells. On the basis of sequence similarity, they are grouped together within the newly defined FAM14 family. Emerging data on ISG12 and G1P3 suggest that both are mitochondrial proteins with opposing activities on apoptosis that may influence the innate immune responses of IFNs. The G1P3 gene encodes a low molecular weight mitochondrial protein that may stabilize mitochondrial function and oppose apoptosis. In contrast, ISG12 expression may sensitize cells to apoptotic stimuli via mitochondrial membrane destabilization. On the basis of these results and differences in induction kinetics between ISG12 and G1P3, we have proposed a model for the role of these genes in mediating cellular activity of IFNs.
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Affiliation(s)
- Venugopalan Cheriyath
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.
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7
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Stark GR. How cells respond to interferons revisited: from early history to current complexity. Cytokine Growth Factor Rev 2007; 18:419-23. [PMID: 17683974 PMCID: PMC2081984 DOI: 10.1016/j.cytogfr.2007.06.013] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A brief account of how I became involved in interferon research is followed by recollections of key experiments that led to the discovery of the roles of the JAKs and STATs in interferon-dependent signaling. I then outline the complex responses of cells to interferons, including the roles of kinases other than JAKs and transcription factors other than STATs, differential responses to interferons alpha and beta, modulation of response by prior exposure to other cytokines ("priming"), cytokine-dependent induction of high level expression of STATs 1 and 3 and the activation of a new set of genes by these unphosphorylated STATs, and diverse patterns of STAT activation in different cell types in response to a single interferon.
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Affiliation(s)
- George R Stark
- Department of Molecular Genetics, Cleveland Clinic, Cleveland OH 44195, United States.
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8
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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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9
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Abstract
Interferons (IFNs) were first characterized as antiviral proteins. Since then, IFNs have proved to be involved in malignant, angiogenic, inflammatory, immune, and fibrous diseases and, thus, possess a broad spectrum of pathophysiologic properties. IFNs activate a cascade of intracellular signaling pathways leading to upregulation of more than 1000 IFN-stimulated genes (ISGs) within the cell. The function of some of the IFN-induced proteins is well described, whereas that of many others remain poorly characterized. This review focuses on three families of small intracellular and intrinsically nonsecreted proteins (10-20 kDa) separated into groups according to their amino acid sequence similarity: the ISG12 group (6-16, ISG12, and ISG12-S), the 1-8 group (9-27/Leu13, 1-8U, and 1-8D), and the ISG15 group (ISG15/UCRP). These IFN-induced genes are abundantly and widely expressed and mainly induced by type I IFN. ISG15 is very well described and is a member of the ubiquitin-like group of proteins. 9-27/Leu-13 associates with CD81/TAPA-1 and plays a role in B cell development. The functions of 1-8U, 1-8D, 6-16, ISG12, and ISG12-S proteins are unknown at present.
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10
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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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11
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Dansako H, Naganuma A, Nakamura T, Ikeda F, Nozaki A, Kato N. Differential activation of interferon-inducible genes by hepatitis C virus core protein mediated by the interferon stimulated response element. Virus Res 2004; 97:17-30. [PMID: 14550584 DOI: 10.1016/s0168-1702(03)00218-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We previously found that hepatitis C virus (HCV) core protein, which possesses the consensus sequence of genotype 1b, transcriptionally activates the interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase (2'-5'-OAS) gene in human hepatocyte cells. To clarify the mechanism of this activation, we further characterized the core protein as an activator of the 2'-5'-OAS gene. We demonstrated that the activation of the 2'-5'-OAS gene by the core protein is a general phenomenon, regardless of HCV genotype and strain. We showed that the 20 N-terminal amino acids (aa) of the core protein were important to the activation of the 2'-5'-OAS gene, although this N-terminal region did not have any effect on the subcellular localization of the core protein. We demonstrated that the core protein was able to activate all promoters possessing the IFN-stimulated response element (ISRE) examined. However, we found that the level of activation of the 2'-5'-OAS gene promoter possessing a particular variant type of ISRE was significantly higher than that of other IFN-inducible gene promoters. This phenomenon was confirmed using synthetic promoters possessing five repeats of the consensus or a 2'-5'-OAS-type ISRE. In addition, we showed that gene activation induced by the core protein is mediated by the ISRE. These results imply that the core protein prefers a subclass of IFN-inducible genes, the promoters of which possess the 2'-5'-OAS-type ISRE. Accordingly, we found that the IFN-inducible double-stranded RNA-specific adenosine deaminase gene promoter, possessing a 2'-5'-OAS-type ISRE sequence, was also efficiently activated by the core protein. The exact mechanism by which the core protein enhances gene expression was not determined, but we could find no effects of core protein on gene expression and phosphorylation status of the components of the JAK-STAT signaling transduction pathway.
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Affiliation(s)
- Hiromichi Dansako
- Department of Molecular Biology, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8558, Japan
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12
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Klampfer L, Huang J, Corner G, Mariadason J, Arango D, Sasazuki T, Shirasawa S, Augenlicht L. Oncogenic Ki-ras inhibits the expression of interferon-responsive genes through inhibition of STAT1 and STAT2 expression. J Biol Chem 2003; 278:46278-87. [PMID: 12972432 DOI: 10.1074/jbc.m304721200] [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: 12/28/2022] Open
Abstract
Endogenous interferon gamma (IFNgamma) promotes the host response to primary tumors, and IFNgamma-insensitive tumors display increased tumorigenicity and can evade tumor surveillance mechanisms. Here we demonstrate that activating mutations of Ki-ras are sufficient to inhibit the expression of STAT1 and STAT2, transcription factors required for signaling by IFNs, providing a potential mechanism for the insensitivity of tumors to IFNs. We demonstrated that colon cancer cell lines with Ki-ras mutations display reduced expression of IFN-responsive genes compared with the cell lines that have retained wild type Ras and that inactivation of the mutant Ki-ras allele in the HCT116 colon cancer cell line is sufficient to restore the expression of STAT1, STAT2, and IRF-9. Accordingly, the expression of 27 interferon-inducible genes was reduced in HCT116 cells compared with the isogenic clones with targeted deletion of the mutant Ki-ras allele, Hkh2 and Hke-3. The expression of IFNgamma receptors did not differ among the isogenic cell lines. IFNgamma stimulated transcription of a STAT1-dependent reporter gene was impaired by RasV12, demonstrating a transmodulation of IFN/STAT signaling by activated Ras. Finally, we demonstrated that the expression of RasV12 in 293T cells is sufficient to inhibit the endogenous expression of STAT1 and STAT2, confirming the negative regulation of IFN signaling by oncogenic Ras. Our data demonstrate that the signaling initiated by activated Ki-ras interferes with the IFN/STAT signaling pathway and modulates the responsiveness of cancer cells to interferons. Furthermore, the data suggest that tumors harboring activating Ki-ras mutations may escape tumor surveillance mechanisms due to reduced responsiveness to IFNgamma.
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Affiliation(s)
- Lidija Klampfer
- Department of Oncology, Albert Einstein Cancer Center, Montefiore Medical Center, 111 E. 210th Street, Bronx, NY 10467, USA.
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13
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Rebouillat D, Hovnanian A, David G, Hovanessian AG, Williams BR. Characterization of the gene encoding the 100-kDa form of human 2',5' oligoadenylate synthetase. Genomics 2000; 70:232-40. [PMID: 11112351 DOI: 10.1006/geno.2000.6382] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The 2'-5' oligoadenylate synthetases (OAS) represent a family of interferon (IFN)-induced proteins implicated in the antiviral action of IFN. When activated by double-stranded (ds) RNA, these proteins polymerize ATP into 2'-5' linked oligomers with the general formula pppA(2'p5'A)n, n greater than or = 1. Three forms of human OAS have been described corresponding to proteins of 40/46, 69/71, and 100 kDa. These isoforms are encoded by three distinct genes clustered on chromosome 12 and exhibit differential constitutive and IFN-inducible expression. Here we describe the structural and functional analysis of the gene encoding the large form of human OAS. This gene has 16 exons with exon/intron boundaries that are conserved among the different isoforms of the human OAS family, reflecting the evolutionary link among them. The promoter region of the p100 gene is composed of multiple features conferring direct inducibility not only by IFNs but also by TNF and all-trans retinoic acid. In contrast, the induction of the p100 promoter by dsRNA is indirect and requires IFN type I production.
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Affiliation(s)
- D Rebouillat
- Department of Cancer Biology, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA
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14
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Chen C, Kim MG, Soo Lyu M, Kozak CA, Schwartz RH, Flomerfelt FA. Characterization of the mouse gene, human promoter and human cDNA of TSCOT reveals strong interspecies homology. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1493:159-69. [PMID: 10978518 DOI: 10.1016/s0167-4781(00)00177-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The regulation of gene expression in thymic epithelial cells is critical for T cell development. The mouse thymic epithelial gene Tscot encodes a protein with weak homology to bacterial 12 transmembrane co-transporters. Using competitive reverse transcription-polymerase chain reaction (RT-PCR), we show that low level Tscot expression is detectable in several other tissues. Tscot was mapped to chromosome 4 and was also detected in other mammalian species by Southern blotting. The human cDNA clone showed 77% amino acid identity with the mouse sequence. The highest conservation was in the TM regions and in a small segment of the central cytoplasmic loop. Genomic clones spanning 17164 bases of the Tscot gene revealed four exons with nine of the TM domains encoded in the first exon. The major transcriptional start site in mouse was identified by a primer extension analysis and confirmed by RT-PCR. Comparison of 1.7 kb of the human and mouse promoters identified six conserved possible regulatory elements, one containing a potential binding site for an interferon alpha inducible factor. Finally, as a functional test, 3 kb of the murine promoter was used to create a transgenic mouse that expresses enhanced green fluorescent protein message strongly in the thymus, weakly in the kidney and undetectably in the spleen, liver and heart.
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Affiliation(s)
- C Chen
- Laboratory of Cellular and Molecular Immunology, Room 111, Building 4, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0420, USA
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15
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Ramana CV, Chatterjee-Kishore M, Nguyen H, Stark GR. Complex roles of Stat1 in regulating gene expression. Oncogene 2000; 19:2619-27. [PMID: 10851061 DOI: 10.1038/sj.onc.1203525] [Citation(s) in RCA: 245] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Stat1 is a fascinating and complex protein with multiple, yet contrasting transcriptional functions. Upon activation, it drives the expression of many genes but also suppresses the transcription of others. These opposing characteristics also apply to its role in facilitating crosstalk between signal transduction pathways, as it participates in both synergistic activation and inhibition of gene expression. Stat1 is a functional transcription factor even in the absence of inducer-mediated activation, participating in the constitutive expression of some genes. This review summarizes the well studied involvement of Stat1 in IFN-dependent and growth factor-dependent signaling and then describes the roles of Stat1 in positive, negative and constitutive regulation of gene expression as well as its participation in crosstalk between signal transduction pathways. Oncogene (2000).
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Affiliation(s)
- C V Ramana
- Department of Molecular Biology, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio, OH 44195 USA
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16
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Köster M, Hauser H. Dynamic redistribution of STAT1 protein in IFN signaling visualized by GFP fusion proteins. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:137-44. [PMID: 10091593 DOI: 10.1046/j.1432-1327.1999.00149.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
STAT proteins (signal transducers and activators of transcription) are a family of transcription factors which are used by many cytokines and cell growth factors for initiating gene expression. They are activated by tyrosine phosphorylation through the cytoplasmic domain of stimulated receptors. Upon phosphorylation STAT proteins dimerize, translocate to the nucleus and activate transcription by binding to specific recognition sites. Different cytokines activate different subsets of STATs and other signaling proteins. We have made use of green fluoresencent protein (GFP) fusion proteins to visualize the subcellular localization and trafficking of STAT1, STAT2 and p48 during interferon (IFN) stimulation and have analysed in detail STAT1-GFP trafficking in living cells. Analysis of GFP fusion proteins allowed the determination of time kinetics of subcellular trafficking in individual living cells. STAT1-GFP is indistinguishable from its wild-type protein displaying strong activity as transcriptional activator as well as the same time kinetics of transport to the nucleus and retreat to the cytoplasm. After prolonged exposure to IFN, STAT1-GFP is no longer retained in the nucleus and relocation to the cytoplasm is observed. Restimulation with the same type of IFN does not lead to repeated nuclear translocation of STAT1-GFP. STAT1 is not subject of inhibition, as restimulation with another type of IFN allows immediate reuse of previously activated STAT1-GFP. However, restimulation with the same type of IFN can be achieved when the primary stimulus is removed after a short induction period. This method of visualizing signal transduction reveals a considerable inhomogeneity with respect to the extent of STAT1-GFP shuttling within a clonal cell population, indicating that competence for full-blasted IFN response is restricted to a cellular subpopulation whereas other cells respond incompletely, retarded or not at all.
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Affiliation(s)
- M Köster
- Department of Gene Regulation and Differentiation, GBF-National Research Institute for Biotechnology, Braunschweig, Germany
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17
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Abstract
Type I interferons (IFNs) constitute a family of structurally related proteins that are all derived from the same ancestral gene and act on a common cell-surface receptor. Contrary to many other cytokines, the production of type I IFNs is not a specialized function, and all cells in the organism can produce them, usually as a result of induction by viruses, via the formation of double-stranded RNA. Type I IFNs are indeed responsible for the first line of defense during virus infection and act through the induction of a great number of proteins. Of these, at least thirty have been characterized, and there are probably many more. In addition to their direct antiviral effect, type I IFNs exert a wide variety of other activities, such as for example the induction of various cytokines and the stimulation of different effector cells of the immune system. Due to these pleiotropic effects, recombinant interferons are used in the clinic to treat a variety of diseases, among which cancer, viral hepatitis and multiple sclerosis.
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Affiliation(s)
- E De Maeyer
- Institut Curie, Université Paris-Sud, Orsay, France
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18
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Wang Q, Floyd-Smith G. Maximal induction of p69 2', 5'-oligoadenylate synthetase in Daudi cells requires cooperation between an ISRE and two IRF-1-like elements. Gene X 1998; 222:83-90. [PMID: 9813254 DOI: 10.1016/s0378-1119(98)00476-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The human 2', 5'-oligoadenylate (2-5A) synthetases are members of a family interferon (IFN)-inducible anti-viral proteins. Three size classes of these enzymes: small (p40, p46), intermediate (p69, p71) and large (p100), are encoded by three genes that exhibit differential constitutive and IFN-inducible expression. Since the 5'-regulatory region of the 69 kDa isoform contains multiple putative control elements, deletion analysis and site directed mutagenesis were done to identify key regulatory motifs. The region located between bp -972 and -452 from the translational start site contains elements that slightly repress constitutive and IFN-inducible transcription. The region from bp -366 to -117 contains two positive regulatory elements that differ slightly from consensus IFN-regulated factor 1 (IRF-1) binding sites. In mobility shift assays, the proximal IRF-1 site weakly binds a novel factor found in both control and IFN-treated cells. The region from bp -117 to -10 contains a functional interferon stimulated response element (ISRE) that contributes to constitutive expression and confers IFN-inducibility on a heterologous promoter. The ISRE specifically binds an IFN-inducible factor that contains signal transducer activator of transcription (STAT) 1alpha. The ISRE and the two IRF-1-like sites cooperatively interact to control transcription. These three elements are sufficient for constitutive and IFN-inducible expression, since expression from reporter constructs containing mutations in all three elements is low in both control and IFN-treated cells.
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Affiliation(s)
- Q Wang
- Molecular and Cellular Biology Program and Department of Biology, Arizona State University, Tempe, AZ 85287-1501, USA
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19
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Abstract
Mutant cell lines B3 and B10, which are unresponsive to both interferon (IFN)-alpha and IFN-gamma, and line B9, which does not respond to IFN-gamma stimulation, are described. The mutants were submitted to fluorescence-activated cell sorting (FACS) from a cellular pool, which was obtained from the parental cell line 2C4 after several rounds of mutagenesis. The unresponsiveness to IFN stimulation was observed both in terms of expression of cell surface markers (CD2, class I and II HLAs) and mRNA expression of IFN-stimulated genes (2'-5' oligoadenylate synthetase (OAS), 9-27, and guanylate binding protein (GBP)). Genetic crossing of B3, B9 and B10 with U3 (STAT1-), gamma 2a (JAK2-) and U4 (JAK1-) mutants, respectively, did not restore IFN responsiveness to the hybrid cell lines. However, when these cell lines were crossed with the same mutants, but using the pairwise crosses B3 x U4, B9 x U3 and B10 x U3, the cell hybrids recovered full IFN responsiveness. The present genetic experiments permitted us to assign the mutant cell lines B3, B9 and B10 to the U3, gamma 2 and U4 complementation groups, respectively. These conclusions were supported by the analysis of IFN-stimulated genes in the mutants.
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Affiliation(s)
- C A Bonjardim
- Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.
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20
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Abstract
Interferons play key roles in mediating antiviral and antigrowth responses and in modulating immune response. The main signaling pathways are rapid and direct. They involve tyrosine phosphorylation and activation of signal transducers and activators of transcription factors by Janus tyrosine kinases at the cell membrane, followed by release of signal transducers and activators of transcription and their migration to the nucleus, where they induce the expression of the many gene products that determine the responses. Ancillary pathways are also activated by the interferons, but their effects on cell physiology are less clear. The Janus kinases and signal transducers and activators of transcription, and many of the interferon-induced proteins, play important alternative roles in cells, raising interesting questions as to how the responses to the interferons intersect with more general aspects of cellular physiology and how the specificity of cytokine responses is maintained.
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Affiliation(s)
- G R Stark
- Lerner Research Institute, Cleveland Clinic Foundation, Ohio 44195, USA.
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21
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Kiermer V, Van Lint C, Briclet D, Vanhulle C, Kettmann R, Verdin E, Burny A, Droogmans L. An interferon regulatory factor binding site in the U5 region of the bovine leukemia virus long terminal repeat stimulates Tax-independent gene expression. J Virol 1998; 72:5526-34. [PMID: 9621009 PMCID: PMC110197 DOI: 10.1128/jvi.72.7.5526-5534.1998] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bovine leukemia virus (BLV) replication is controlled by both cis- and trans-acting elements. The virus-encoded transactivator, Tax, is necessary for efficient transcription from the BLV promoter, although it is not present during the early stages of infection. Therefore, sequences that control Tax-independent transcription must play an important role in the initiation of viral gene expression. This study demonstrates that the R-U5 sequence of BLV stimulates Tax-independent reporter gene expression directed by the BLV promoter. R-U5 was also stimulatory when inserted immediately downstream from the transcription initiation site of a heterologous promoter. Progressive deletion analysis of this region revealed that a 46-bp element corresponding to the 5' half of U5 is principally responsible for the stimulation. This element exhibited enhancer activity when inserted upstream or downstream from the herpes simplex virus thymidine kinase promoter. This enhancer contains a binding site for the interferon regulatory factors IRF-1 and IRF-2. A 3-bp mutation that destroys the IRF recognition site caused a twofold decrease in Tax-independent BLV long terminal repeat-driven gene expression. These observations suggest that the IRF binding site in the U5 region of BLV plays a role in the initiation of virus replication.
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Affiliation(s)
- V Kiermer
- Department of Molecular Biology, University of Brussels, B1640 Rhode-Saint-Genèse, Belgium.
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22
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Yao XL, Ikezono T, Cowan M, Logun C, Angus CW, Shelhamer JH. Interferon-gamma stimulates human Clara cell secretory protein production by human airway epithelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:L864-9. [PMID: 9612303 DOI: 10.1152/ajplung.1998.274.5.l864] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Clara cell secretory protein (CCSP) is an inhibitor of secretory phospholipase A2. It is produced by airway epithelial cells and is present in airway secretions. Because interferon (IFN)-gamma can induce gene expression in airway epithelial cells and may modulate the inflammatory response in the airway, it was of interest to study the effect of this cytokine on epithelial cell CCSP mRNA expression and CCSP protein synthesis. A human bronchial epithelial cell line (BEAS-2B) was used for this study. CCSP mRNA was detected by ribonuclease protection assay. IFN-gamma was found to increase CCSP mRNA expression in a time- and dose-dependent manner. The CCSP mRNA level increased after IFN-gamma (300 U/ml) treatment for 8-36 h, with the peak increase at 18 h. Immunobloting of CCSP protein also demonstrated that IFN-gamma induced the synthesis and secretion of CCSP protein in a time-dependent manner. Nuclear run-on, CCSP reporter gene activity assay, and CCSP mRNA half-life assay demonstrated that IFN-gamma-induced increases in CCSP gene expression were mediated, at least in part, at the posttranscriptional level. The present study demonstrates that IFN-gamma can induce increases in steady-state mRNA levels and protein synthesis of human CCSP protein in airway epithelial cells and may modulate airway inflammatory responses in this manner.
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Affiliation(s)
- X L Yao
- Critical Care Medicine Department, National Institutes of Health, Bethesda, Maryland 20892, USA
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23
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Lee CG, Eki T, Okumura K, da Costa Soares V, Hurwitz J. Molecular analysis of the cDNA and genomic DNA encoding mouse RNA helicase A. Genomics 1998; 47:365-71. [PMID: 9480750 DOI: 10.1006/geno.1997.5139] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RNA helicase A is an enzyme that possesses both RNA and DNA helicase activities. In this report, we describe the isolation of a mouse cDNA encoding RNA helicase A. The deduced amino acid sequence derived from mouse RNA helicase A cDNA exhibits 87 and 47% identity to its human and Drosophila homologs, respectively. Using Southern blot analysis employing a mouse backcross panel, we have assigned the mouse RNA helicase A gene to chromosome 1, mapping near the D1Bir20 locus at MGD position 67. Northern blot and primer extension analyses indicate that, although its level is variable, RNA helicase A appears to be expressed from a single transcription start site in all tissues tested. Sequence analysis of the upstream genomic DNA revealed that the promoter region lacks a TATA box and contains two high-affinity sites for Sp1, one ISRE, a binding site for interferon regulatory factor, and three AP2-binding sites. These findings suggest that the transcriptional regulation of the RNA helicase A gene is complex.
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Affiliation(s)
- C G Lee
- Graduate Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021, USA
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24
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Abstract
The interaction of proteins with DNA is a central theme of molecular biology. In this article, we review some of the principal techniques currently used for the identification and characterization of DNA binding proteins, and for investigation of the molecular interactions that are responsible for the recognition of specific DNA sequences.
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Affiliation(s)
- M J Guille
- Division of Molecular and Cell Biology, School of Biological Science, University of Portsmouth, UK
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25
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Gongora C, David G, Pintard L, Tissot C, Hua TD, Dejean A, Mechti N. Molecular cloning of a new interferon-induced PML nuclear body-associated protein. J Biol Chem 1997; 272:19457-63. [PMID: 9235947 DOI: 10.1074/jbc.272.31.19457] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Transcriptional induction of genes is an essential part of the cellular response to interferons. We have established a cDNA library from human lymphoblastoid Daudi cells treated for 16 h with human alpha/beta-interferon (IFN) and made use of differential screening to search for as yet unidentified IFN-regulated genes. In the course of this study, we have isolated a human cDNA that codes for a 20-kDa protein sharing striking homology with the product of the Xenopus laevis XPMC2 gene. This new gene is induced by both type I and II IFNs in various cell lines and will be referred to as ISG20 for interferon-stimulated gene product of 20 kDa. Confocal immunofluorescence analysis of the subcellular localization of ISG20 protein reveals that it is closely associated with PML and SP100 gene products within the large nuclear matrix-associated multiprotein complexes termed the PML nuclear bodies.
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Affiliation(s)
- C Gongora
- Institut de Genetique Moleculaire de Montpellier-UMR 9942, CNRS, 34033 Montpellier Cedex 1, France
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26
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Abstract
A recessive mutant cell line, B7, which is partially responsive to both interferon (IFN)-alpha and IFN-gamma is described. B7 was FACS sorted from a cellular pool, which was obtained from the parental cell line 2C4, after several rounds of mutagenesis. The partial responsiveness to IFN was observed both in terms of expression of cell surface markers (CD2, class I and II HLAs) and mRNA expression of IFN-stimulated genes (9-27; 6-16; 2'-5' OAS; GBP and HLA-DR alpha). A genetic cross with the U4 mutant (JAK1-, a member of the Janus family of nonreceptor tyrosine kinase) did not restore full IFN responsiveness to B7, and JAK1 cDNA transfection into B7 restored the wild phenotype of the cell line, defining B7 as a member of the U4 complementation group. Nevertheless, JAK1 mRNA was not detected in this mutant. Transcriptional regulator complexes such as IRF1/2 (IFN-regulatory factor) and ISGF3-gamma (IFN-stimulated gene factor) were constitutively formed in the B7 mutant and co-migrated with the IFN-induced complexes expressed in the parental cell line 2C4. Thus, this cell line seems to be useful for understanding cis-acting elements governing JAK1 mRNA expression.
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Affiliation(s)
- C A Bonjardim
- Departamento de Microbiologia, Universidade Federal de Minas Gerais, Brasil.
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27
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Rutherford MN, Kumar A, Haque SJ, Ghysdael J, Williams BR. Specific binding of the ETS-domain protein to the interferon-stimulated response element. J Interferon Cytokine Res 1997; 17:1-10. [PMID: 9041465 DOI: 10.1089/jir.1997.17.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Interferon (IFN) activation of genes bearing an IFN-stimulated response element (ISRE) is regulated through binding of IFN-stimulated gene factors (ISGF) to the ISRE found in many IFN-stimulated genes. Using a multimerized human 2-5A synthetase ISRE as probe, we screened lambda gt11 expression libraries for cDNA encoding ISRE-binding activity and isolated a clone for murine proto-oncogene ets-1. The Ets-1 protein binds to the 2-5A synthetase ISRE at a site that also binds ISGF3, a multicomponent factor whose ISRE binding correlates with IFN-induced activation of transcription from ISRE-containing promoters. IFN-induced ISGF3 complex formation on the ISRE can be inhibited by specific Ets-1 antibody. Coexpression of Ets-1 represses ISRE-dependent reporter activity, suggesting that one or more members of the Ets protein family may negatively regulate transcriptional activity mediated by the 2-5A synthetase ISRE.
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Affiliation(s)
- M N Rutherford
- Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada
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28
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Wehinger J, Gouilleux F, Groner B, Finke J, Mertelsmann R, Weber-Nordt RM. IL-10 induces DNA binding activity of three STAT proteins (Stat1, Stat3, and Stat5) and their distinct combinatorial assembly in the promoters of selected genes. FEBS Lett 1996; 394:365-70. [PMID: 8830676 DOI: 10.1016/0014-5793(96)00990-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Interaction of IL-10 with its receptor leads to the activation of STAT transcription factors. Herein we report the IL-10 dependent simultaneous activation of three STAT transcription factors: Stat1, Stat3, and Stat5. Upon IL-10 treatment multiple Stat proteins become simultaneously activated, and bind to different promoters with equal kinetics but form distinct homo- and heterodimeric transcriptionally active complexes depending on the STAT-consensus elements of a selected gene promoter. Upon IL-10 treatment Stat1, 3, and 5 bind to the GRR of the FcgammaRI gene, activated Stat1 and 3 bind to the SIE sequence of the c-fos promoter and transcriptionally active Stat5 assembles at the PRL-STAT consensus sequence of the beta-casein gene. Thus, functionally relevant STAT dimerization is influenced by the activated cytokine receptor as well as the specific STAT consensus sequence present in a specific gene promoter.
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Affiliation(s)
- J Wehinger
- University of Freiburg Medical Center, Department of Hematology and Oncology, Freiburg, Germany
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29
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Murphy LC, Huzel N, Davie JR. Novel DNase I hypersensitive sites in the 3'-flanking region of the human c-myc gene. DNA Cell Biol 1996; 15:543-8. [PMID: 8756335 DOI: 10.1089/dna.1996.15.543] [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: 02/02/2023] Open
Abstract
DNase I hypersensitivity regions correlate with genetic regulatory loci and binding sites for sequence-specific DNA-binding proteins. We present data supporting the presence of novel DNase 1 hypersensitive sites (which we have designated sites VI-IX) in both the body of the human c-myc gene downstream from exon 2 and the 3'-flanking region of the c-myc gene in HL-60 cells. All of these novel DH sites are markedly decreased when HL-60 cells are treated with either dimethyl sulfoxide (DMSO) or retinoic acid. Moreover, a similar pattern of DNase I hypersensitive sites in this region of c-myc was present in MCF-7 human breast cancer cells growing in culture. Our results suggest a potential role for these sites in transcriptional regulation of the human c-myc gene.
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Affiliation(s)
- L C Murphy
- Department of Biochemistry and Molecular Biology, University of Manitoba, Winnipeg, Canada
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30
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Flati V, Haque SJ, Williams BR. Interferon-alpha-induced phosphorylation and activation of cytosolic phospholipase A2 is required for the formation of interferon-stimulated gene factor three. EMBO J 1996; 15:1566-71. [PMID: 8612580 PMCID: PMC450066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Treatment of cells with interferon (IFN)-alpha caused phosphorylation and activation of cytosolic phospholipase A2 (cPLA2). The protein tyrosine kinase Jak1 was found to be necessary for the activation of cPLA2. Jak1 could be co-immunoprecipitated with cPLA2 from cell extracts, indicating that a close physical interaction occurs between these two proteins. The induction of IFN-stimulated gene factor three (ISGF3) by IFN-alpha, is blocked by cPLA2 inhibitors in cell cultures and in cell-free reconstituted systems. However, these inhibitors do not block IFN-alpha or gamma-induced binding of STAT1 to the inverted repeat (IR) element of the IFN regulatory factor 1 (IRF-1) gene. Thus, cPLA2 activations occurs as an early event in the IFN-alpha response and is selectively involved in ISGF3-dependent gene activation.
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Affiliation(s)
- V Flati
- Department of Cancer Biology, Cleveland Clinic Foundation, OH 44195, USA
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31
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Kalvakolanu DV, Borden EC. An overview of the interferon system: signal transduction and mechanisms of action. Cancer Invest 1996; 14:25-53. [PMID: 8597888 DOI: 10.3109/07357909609018435] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- D V Kalvakolanu
- Department of Microbology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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32
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Bandyopadhyay SK, Leonard GT, Bandyopadhyay T, Stark GR, Sen GC. Transcriptional induction by double-stranded RNA is mediated by interferon-stimulated response elements without activation of interferon-stimulated gene factor 3. J Biol Chem 1995; 270:19624-9. [PMID: 7642650 DOI: 10.1074/jbc.270.33.19624] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Many genes induced by type I interferons (IFNs) are also induced by double-stranded (ds)RAN. In this study, we investigated the mechanism of this induction process. Using cell lines from which the type I IFN genes have been deleted, we established that induction by dsRNA of the IFN-inducible 561 gene is direct and not mediated by the intermediate synthesis of IFN. Unlike 561 mRNA, the IFN-inducible 6-16 mRNA was induced poorly by dsRNA. Transfection studies demonstrated that the sequence difference between the core IFN-stimulated response elements (ISREs) of these two genes is not responsible for their differential inducibility by dsRNA. A point mutation in the 561 ISRE that abolished its response to IFN-alpha also made it unresponsive to dsRNA, thus demonstrating that the ISRE is the relevant cis-acting element for dsRNA signaling. The roles of different known ISRE-binding protein and tyrosine kinases in transducing the signal elicited by dsRNA were evaluated in genetically altered cell lines. dsRNA failed to induce 561 mRNA in cells expressing an anti-sense RNA for interferon regulatory factor 1, whereas it was induced strongly in cells expressing the corresponding sense mRNA. 561 mRNA was also induced strongly by dsRNA, but not by IFN-alpha, in mutant cell lines that do not express functional tyrosine kinases Tyk2 or JAK1 or ISRE binding protein, p48, or STAT2, all of which are required for IFN-alpha signaling. However, in cells devoid of functional STAT1, which is also required for IFN-alpha signaling, the induction of 561 mRNA by dsRNA was very low. Expression of transfected STAT1 alpha protein, but not of STAT 1beta protein, in these cells greatly enhanced the dsRNA inducibility of the 561 gene. These studies indicated that the major ISRE-mediated signaling pathway used by dsRNA requires interferon regulatory factor 1 and STAT alpha. This pathway, however, does not require the other known cytoplasmic components used for IFN-alpha signaling.
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Affiliation(s)
- S K Bandyopadhyay
- Department of Molecular Biology, Cleveland Clinic Foundation, Ohio 44195, USA
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33
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Tissot C, Mechti N. Molecular cloning of a new interferon-induced factor that represses human immunodeficiency virus type 1 long terminal repeat expression. J Biol Chem 1995; 270:14891-8. [PMID: 7797467 DOI: 10.1074/jbc.270.25.14891] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Transcriptional induction of genes is an essential part of the cellular response to interferons. To isolate yet unidentified IFN-regulated genes we have performed a differential screening on a cDNA library prepared from human lymphoblastoid Daudi cells treated for 16 h with human alpha/beta interferon (Hu-alpha/beta IFN). In the course of these studies we have isolated a human cDNA which codes for a protein sharing homology with the mouse Rpt-1 gene; it will be referred as Staf-50 for Stimulated Trans-Acting Factor of 50 kDa. Amino acid sequence analysis revealed that Staf-50 is a member of the Ring finger family and contains all the features of a transcriptional regulator able to initiate a second cascade of gene induction (secondary response). Staf-50 is induced by both type I and type II IFN in various cell lines and down-regulates the transcription directed by the long terminal repeat promoter region of human immunodeficiency virus type 1 in transfected cells. These data are consistent with a role of Staf-50 in the mechanism of transduction of the IFN antiviral action.
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Affiliation(s)
- C Tissot
- Institut de Genetique Moleculaire de Montpellier-UMR 9942, CNRS, France
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34
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Waring JF, Radford JE, Burns LJ, Ginder GD. The human leukocyte antigen A2 interferon-stimulated response element consensus sequence binds a nuclear factor required for constitutive expression. J Biol Chem 1995; 270:12276-85. [PMID: 7744880 DOI: 10.1074/jbc.270.20.12276] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Both constitutive and interferon-inducible enhancer-like elements have been identified previously in the promoter of human leukocyte antigen (HLA) class I genes. One of these sites is termed the interferon-stimulated response element (ISRE). We have tested the function of an ISRE consensus sequence in the human HLA class I gene HLA-A2 and confirmed previous studies that showed that the HLA-A2 ISRE consensus sequence does not mediate a response to interferons. However, deletion of the ISRE consensus sequence caused a several-fold reduction in the constitutive expression of the HLA-A2 gene in K562 and Jurkat cells. Mobility shift assays performed with the HLA-A2 ISRE revealed the presence of a constitutive binding protein (ISRE/CBP). This protein binds specifically to the HLA-A2 ISRE sequence, and binding is not efficiently competed by the ISRE sequences of the HLA-B7 or ISG54 genes. Substitution of the HLA-B7 or ISG54 ISRE sequences for the HLA-A2 ISRE sequence caused a severalfold reduction in the constitutive expression of the HLA-A2 gene. Mass determinations showed the ISRE/CBP to be 105 kDa, different than any previously characterized ISRE binding proteins. We propose that ISRE/CBP is a novel positive transcriptional regulatory factor for the HLA-A2 gene that may contribute to the differential expression of HLA-A versus HLA-B genes.
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Affiliation(s)
- J F Waring
- Department of Medicine, University of Minnesota, Minneapolis 55455, USA
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35
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Eid P, Tovey MG. Characterization of a domain of a human type I interferon receptor protein involved in ligand binding. J Interferon Cytokine Res 1995; 15:205-11. [PMID: 7584665 DOI: 10.1089/jir.1995.15.205] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Two monoclonal antibodies that recognize different epitopes of the extracellular domain of one of the proteins that constitute the type I interferon receptor were used to delineate the interferon binding site. Antibody 64G12 both inhibits the binding of radiolabeled interferon-alpha 2 and IFN-alpha 8 to their cell surface receptors and neutralizes the antiviral and antiproliferative actions of all the type I interferons tested, including IFN-beta, IFN-omega, and human leukocyte IFN, a mixture of different interferon-alpha isotypes. Antibody 34F10 recognizes the type I interferon receptor with an affinity similar to that of the MAb 64G12 but does not inhibit either the binding or the biologic activity of any of the type I interferons tested. Both antibodies recognize a protein of 105 +/- 5 kD from either Daudi or Ly28 cells. Immunoprecipitation following surface iodination demonstrated that the neutralizing MAb recognizes a protein of 105 kD and the nonneutralizing MAb a protein of 110 kD in extracts of Daudi cells. A second less intense band was also detected by both antibodies. Cross-linking of IFN-alpha 2 to its receptor before immunoprecipitation prevented the neutralizing antibody from immunoprecipitating the receptor protein, but the nonneutralizing MAb was still able to recognize a 140 kD protein corresponding to the cross-linked interferon-receptor protein complex. Thus, an interferon binding domain appears to be localized in a region between amino acids 23 and 229 of the extracellular domain of a transmembrane protein that forms part of the type I interferon receptor complex containing the epitopes recognized by each antibody.
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Affiliation(s)
- P Eid
- Laboratory of Viral Oncology, CNRS, Villejuif, France
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36
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McNabb DS, Xing Y, Guarente L. Cloning of yeast HAP5: a novel subunit of a heterotrimeric complex required for CCAAT binding. Genes Dev 1995; 9:47-58. [PMID: 7828851 DOI: 10.1101/gad.9.1.47] [Citation(s) in RCA: 200] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The CCAAT-binding factor is a conserved heteromeric transcription factor that binds to CCAAT box-containing upstream activation sites (UASs) within the promoters of numerous eukaryotic genes. The CCAAT-binding factor of Saccharomyces cerevisiae activates the transcription of these genes in response to growth in a nonfermentable carbon source. Previous studies have demonstrated that the HAP2, HAP3, and HAP4 subunits of the yeast CCAAT-binding factor are required for the transcriptional activation of genes containing a CCAAT box. Using the two-hybrid screening method, we have identified an additional component of the CCAAT-binding factor. We present the identification and characterization of a novel gene, HAP5, that encodes an additional subunit of the CCAAT-binding factor required for the assembly and DNA-binding activity of the complex. In a hap5 mutant, we show that CCAAT-binding activity is abolished in vitro. Furthermore, we demonstrate that purified recombinant HAP2, HAP3, and HAP5 are able to reconstitute CCAAT-binding activity in mobility shift analysis. These data suggest that the HAP2/3/5 heterotrimer represents a unique DNA-binding factor in which all three subunits of the complex are absolutely required for DNA-binding activity.
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Affiliation(s)
- D S McNabb
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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37
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Stasiv YZ, Mashkova TD, Chernov BK, Sokolova IV, Itkes AV, Kisselev LL. Cloning of a cDNA encoding a human protein which binds a sequence in the c-myc gene similar to the interferon-stimulated response element. Gene 1994; 145:267-72. [PMID: 8056341 DOI: 10.1016/0378-1119(94)90018-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A human cDNA clone encoding a c-myc promoter-binding protein (IRLB) was selected by screening a human fibroblast lambda gt11 phage library with the hexamer oligodeoxyribonucleotide (oligo) 5'-GGCGGGAAAAAGAACGGA, corresponding to the protein-binding element of human c-myc similar to the interferon-stimulated response element (ISRE). The lambda gt11 phage clone, encoding a fusion protein which bound the probe oligo, was used to create an strain of Escherichia coli. The deduced amino-acid sequence of the cloned protein contains a putative alpha-helix which is expected to act as the DNA-binding domain. DNase footprinting analysis and oligo-binding specificity assays showed that the cloned factor recognizes the ISRE-like element of the P2 promoter region of human c-myc.
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Affiliation(s)
- Y Z Stasiv
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow
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Haque S, Williams B. Identification and characterization of an interferon (IFN)-stimulated response element-IFN-stimulated gene factor 3-independent signaling pathway for IFN-alpha. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32200-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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39
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Darnell JE, Kerr IM, Stark GR. Jak-STAT pathways and transcriptional activation in response to IFNs and other extracellular signaling proteins. Science 1994; 264:1415-21. [PMID: 8197455 DOI: 10.1126/science.8197455] [Citation(s) in RCA: 4473] [Impact Index Per Article: 149.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Through the study of transcriptional activation in response to interferon alpha (IFN-alpha) and interferon gamma (IFN-gamma), a previously unrecognized direct signal transduction pathway to the nucleus has been uncovered: IFN-receptor interaction at the cell surface leads to the activation of kinases of the Jak family that then phosphorylate substrate proteins called STATs (signal transducers and activators of transcription). The phosphorylated STAT proteins move to the nucleus, bind specific DNA elements, and direct transcription. Recognition of the molecules involved in the IFN-alpha and IFN-gamma pathway has led to discoveries that a number of STAT family members exist and that other polypeptide ligands also use the Jak-STAT molecules in signal transduction.
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Affiliation(s)
- J E Darnell
- Laboratory of Molecular Cell Biology, Rockefeller University, New York, NY 10021
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40
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Gariglio M, Gaboli M, Mana C, Ying GG, Gribaudo G, Cavallo R, Landolfo S. Characterization of nuclear factors involved in 202 gene induction by interferon-alpha in murine leukemia cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 221:731-9. [PMID: 8174552 DOI: 10.1111/j.1432-1033.1994.tb18786.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The 5' terminal flanking region of the interferon-inducible gene, 202, contains an interferon-stimulable response element (ISRE), called a GA box, that confers inducibility by interferon(IFN)-alpha, but not by IFN-gamma, on a reporter gene, such as the chloramphenicol acetyltransferase (CAT). Nuclear extracts from L1210 murine leukemia cells, stimulated for various periods of time with IFN-alpha, were mixed with 32P-labeled GA box and analyzed for the presence of retarded complexes in electrophoretic-mobility-shift assays. In addition to a few constitutive retarded complexes, an inducible GA box-binding activity (GAbf-1) appeared after 5 min, peaked at about 2 h, and was still abundant 12 h after IFN-alpha treatment. In the cytoplasmic fraction GAbf-1 was not detectable before 30 min, continued to increase up to 2 h, but had disappeared within 12 h. GAbf-1 activity was not observed in nuclear extracts treated with IFN-gamma, and was not inhibited by prior treatment with the protein-synthesis inhibitor cycloheximide. When the binding properties of GAbf-1 were compared with those of ISGF-3, the primary transcriptional activator for IFN-alpha-induced genes, a different pattern of retarded complexes was observed. Moreover, as observed by immunoblotting analysis, nuclear extracts from IFN-alpha-treated L1210 cells did not contain the p91/84 subunit of the ISGF3, the best characterized nuclear complex activated by IFN-alpha. Altogether these results indicate that GAbf-1 may be a novel transcription factor exploited by IFN-alpha to activate the 202 inducible gene in murine pre-B leukemia cells.
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Affiliation(s)
- M Gariglio
- Institute of Microbiology, Medical School, University of Torino, Italy
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Abstract
Recent studies on gene activation by interferons have uncovered a direct signaling pathway from the cell-surface receptor for interferons to the nucleus. Activation of JAK tyrosine kinases by interferons leads to activation, by direct tyrosine phosphorylation, of a family of latent cytoplasmic transcription factors named STATs (for signal transducers and activators of transcription), which then translocate to the nucleus to direct transcriptional activation.
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Affiliation(s)
- K Shuai
- Laboratory of Molecular Cell Biology, Rockefeller University, New York, NY 10021
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43
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Roy C. Triple-helix formation interferes with the transcription and hinged DNA structure of the interferon-inducible 6-16 gene promoter. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:493-503. [PMID: 7510230 DOI: 10.1111/j.1432-1033.1994.tb18648.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The interferon responsive element (IRE) of the 6-16 gene lies within two 39-bp elements in tandem. A purine-rich oligodeoxynucleotide, oligo(dN), was found to be able to pair with the purine-rich strand of the IRE in an antiparallel orientation which led to triple-helix formation with Mg2+ being necessary for triplex stability. Footprinting analysis confirmed these results. The interaction between the IRE and the oligo(dN) was reversible and had a Kd equal to 20 nM. The two repeats of the 6-16 gene IRE can form a hinged DNA structure through pairing of their purine-rich regions; exonuclease III experiments support this model. The hybrid DNA structure leads to a parallel pairing of the purine strands of the 6-16 gene IRE and this conformation was shown to be destabilized by triplex formation. When co-transfected with a reporter gene whose promoter was under the control of the 6-16 gene IRE, the triple-helix-forming oligo(dN)s inhibit the interferon-induced stimulation of the reporter gene with complete inhibition being obtained with 1 microM oligo(dN) at the time of transfection. When added to the cell culture medium after transfection, the concentrations of oligo(dN) needed to obtain 50% inhibition of the interferon effect on gene transcription must be 50-100 times higher. Besides the existence of a peculiar structure for the 6-16 gene IRE, the possibility of interfering with gene expression by means of oligo(dN)s is demonstrated.
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Affiliation(s)
- C Roy
- Institut de Génétique Moléculaire, UMR 9942, C. N. R. S., Montpellier, France
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Bluyssen HA, Vlietstra RJ, van der Made A, Trapman J. The interferon-stimulated gene 54 K promoter contains two adjacent functional interferon-stimulated response elements of different strength, which act synergistically for maximal interferon-alpha inducibility. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:395-402. [PMID: 8125096 DOI: 10.1111/j.1432-1033.1994.tb18636.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The interferon-alpha(IFN-alpha)-regulated hamster ISG-54 K gene, which is activated in hamster CHO-12 cells at least 40-fold, was isolated and the promoter region was characterized in detail. Sequence analysis revealed the presence of two elements, closely related to the interferon-stimulated-response-element (ISRE) consensus sequence [AGTTTCNNTTTC(CT)]. The putative ISRE-I sequence (GGTTTCAATTTCT) is located at position -97 to -85; ISRE-II (AGTTTTACTTTCT), which differs at three positions from ISRE-I, is found directly upstream of ISRE-I at position -110 to -98. In a transient transfection assay in CHO-12 cells the wild-type hamster ISG-54K-promoter-chloramphenicol-acetyl-transferase (CAT) reporter construct showed a 40-80-fold induction, offering an excellent model to study the functional properties of the two ISRE. To find out whether both elements were functional in interferon regulation of the promoter, selected point mutations were introduced in the -110 to -85 region and in flanking sequences. The (mutated) ISG-54 K promoter was linked to the CAT reporter gene and transiently expressed in CHO cells in the absence and presence of murine (Mu)IFN-alpha 6. Transfections showed that both the -97 to -85 (ISRE-I) and the -110 to -98 (ISRE-II) segment were needed for optimal interferon induction of the ISG-54 K promoter. However, ISRE-I has an approximately sevenfold stronger activity compared to ISRE-II. Sequential substitution of the three ISRE-I bases, which differ in ISRE-II showed that the T at position -105 causes the lower activity of ISRE-II. Transfection of ISG-54 K promoter constructs, in which ISRE-I was replaced by ISRE-II, which generates a promoter with two ISRE-II segments, and vice versa (two ISRE-I), provided further evidence for a role of both elements in IFN-alpha induction. Importantly, all data obtained in transfection studies show that the two ISRE cooperate synergistically. The mechanism of synergism is most probably an indirect interaction between transcription factors binding to the ISRE, because an increase in the spacial arrangement of the two ISRE with a complete helical turn or half a turn did not result in a substantial decrease in promoter activity.
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Affiliation(s)
- H A Bluyssen
- Department of Pathology, Erasmus University, Rotterdam, The Netherlands
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45
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Ozes ON, Taylor MW. Reversal of interferon-gamma-resistant phenotype by poly(I:C): possible involvement of ISGF2 (IRF1) in interferon-gamma-mediated induction of the IDO gene. JOURNAL OF INTERFERON RESEARCH 1994; 14:25-32. [PMID: 8027591 DOI: 10.1089/jir.1994.14.25] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Indoleamine 2,3-dioxygenase (IDO) is induced in many cell lines by interferon-gamma (IFN-gamma) treatment. IDO mRNA increases rapidly from 4 h after IFN-gamma treatment to at least 24 h after treatment in ME180 cells. The IFN-gamma-resistant mutant of ME180, IR3B6B, expresses only one-sixth the amount of IDO message after IFN-gamma treatment and very low levels of IDO. However, pretreatment of these mutants with poly(I:C) restores normal levels of IDO mRNAs and IDO activity. Since IRF1 mRNA induction is also low in IR3B6B cells after IFN-gamma treatment, we examined whether there was any relationship between IRF1 induction and IDO induction by IFN-gamma. The steady-state level of IRF1 mRNA was elevated by treating IR3B6B cells with poly(I:C) and IFN-gamma. Poly(I:C)-mediated reversal of IFN-gamma-resistant phenotype and induction of IDO and IRF1 messages are inhibited by 2-aminopurine. Transient transfection of IRF1 cDNA in ME180 cells resulted in activation of IDO transcription. Nuclear extracts prepared from IFN-gamma-treated ME180 and IR3B6B cells affected differently the mobility of a 80-bp DNA fragment of the 5' regulatory region of IDO gene. Pretreatment of IR3B6B cells with poly(I:C) and addition of IFN-gamma resulted in increased DNA binding of nuclear proteins to the DNA. Pre- and post-treatment of nuclear extract of IFN-gamma-treated ME180 cells with anti-IRF1 antibody resulted in a super shift in mobility of the probe with the abolishment of normal gel-shift pattern.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- O N Ozes
- Department of Biology, Indiana University, Bloomington 47405
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46
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Guille MJ, Laxton CD, Rutherford MN, Williams BR, Kerr IM. Functional differences in the promoters of the interferon-inducible (2'-5')A oligoadenylate synthetase and 6-16 genes in interferon-resistant Daudi cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 219:547-53. [PMID: 8307020 DOI: 10.1111/j.1432-1033.1994.tb19970.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A clone of interferon-alpha-resistant (IFNr) Daudi cells retained much greater transcriptional inducibility of the (2'-5') oligoadenylate synthetase than the 6-16 gene despite the fact that the response of both genes is mediated by highly similar interferon-stimulable DNA response elements (ISRE). The primary IFN-alpha activatable transcription factor E (ISGF3) and the additional IFN-alpha-inducible ISRE-binding complex M were greatly reduced in the IFNr cells. The defect in E was in the E alpha subunit. In electrophoretic mobility-shift assays the 6-16 and (2'-5') oligoadenylate synthetase ISRE competed approximately equivalently for E and M. Moreover although active in wild-type cells the (2'-5') oligoadenylate synthetase ISRE was no more capable of conferring inducibility on a reporter gene in the IFNr cells than was the 6-16 ISRE. The contrasting response of the endogenous (2'-5') oligoadenylate synthetase and 6-16 genes in the IFNr cells is, therefore, unlikely simply to reflect the slight difference in the sequence of their ISRE. Consistent with this, in addition to the ISRE, sequences 5' to the ISRE in the (2'-5') oligoadenylate synthetase promoter appeared necessary for good induction by IFN alpha in the IFNr cells. Subtle quantitative changes in the phenotype of the IFNr cells have, however, precluded a more precise definition of the DNA element(s) involved.
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Affiliation(s)
- M J Guille
- Imperial Cancer Research Fund Laboratories, London, England
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47
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Hayes MP, Zoon KC. Production and action of interferons: new insights into molecular mechanisms of gene regulation and expression. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1994; 43:239-70. [PMID: 7531856 DOI: 10.1007/978-3-0348-7156-3_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M P Hayes
- Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892
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48
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Affiliation(s)
- A R Clark
- Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, U.K
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49
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Müller M, Laxton C, Briscoe J, Schindler C, Improta T, Darnell JE, Stark GR, Kerr IM. Complementation of a mutant cell line: central role of the 91 kDa polypeptide of ISGF3 in the interferon-alpha and -gamma signal transduction pathways. EMBO J 1993; 12:4221-8. [PMID: 7693454 PMCID: PMC413716 DOI: 10.1002/j.1460-2075.1993.tb06106.x] [Citation(s) in RCA: 308] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Mutants in complementation group U3, completely defective in the response of all genes tested to interferons (IFNs) alpha and gamma, do not express the 91 and 84 kDa polypeptide components of interferon-stimulated gene factor 3 (ISGF3), a transcription factor known to play a primary role in the IFN-alpha response pathway. The 91 and 84 kDa polypeptides are products of a single gene. They result from differential splicing and differ only in a 38 amino acid extension at the C-terminus of the 91 kDa polypeptide. Complementation of U3 mutants with cDNA constructs expressing the 91 kDa product at levels comparable to those observed in induced wild-type cells completely restored the response to both IFN-alpha and -gamma and the ability to form ISGF3. Complementation with the 84 kDa component similarly restored the ability to form ISGF3 and, albeit to a lower level, the IFN-alpha response of all genes tested so far. It failed, however, to restore the IFN-gamma response of any gene analysed. The precise nature of the DNA motifs and combination of factors required for the transcriptional response of all genes inducible by IFN-alpha and -gamma remains to be established. The results presented here, however, emphasize the apparent general requirement of the 91 kDa polypeptide in the primary transcriptional response to both types of IFN.
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Affiliation(s)
- M Müller
- Imperial Cancer Research Fund Laboratories, London, UK
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50
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Dron M, Tovey MG. Interferon-resistant Daudi cells are deficient in interferon-alpha-induced ISGF3 alpha activation, but remain sensitive to the interferon-alpha-induced increase in ISGF3 gamma content. JOURNAL OF INTERFERON RESEARCH 1993; 13:377-83. [PMID: 8301159 DOI: 10.1089/jir.1993.13.377] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Low levels of the transcription factor ISGF3 alpha were detected in the cytoplasm and nucleus of untreated Daudi cells, which increased markedly following interferon (IFN) treatment. In contrast no ISGF3 alpha was detected in an IFN-resistant clone of Daudi cells, DIF8, and only low levels were detected in these cells after IFN-alpha treatment. High levels of ISGF3 were produced in vitro, however, by the addition of ISGF3 alpha to extracts of IFN-treated DIF8 cells, indicating that IFN is unable to produce substantial amounts of functional ISGF3 alpha in DIF8 cells. A second clone of IFN-resistant Daudi cells, DIF3, also exhibited defective ISGF3 alpha production, which was restored to normal in the subclone DIF3REV5 that had reverted to high IFN sensitivity. Thus, the antiproliferative effect of IFN on Daudi cells and derived clones is closely related to the level of ISGF3 present in the nucleus of these cells. IFN-alpha, however, also enhances the content of ISGF3 gamma in IFN-resistant cells as well as certain proteins of unknown function, raising the possibility that a second pathway of IFN-alpha signal transduction, distinct from the ISGF3 pathway, remains functional in both DIF8 and DIF3 cells.
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Affiliation(s)
- M Dron
- Laboratoire d'oncologie virale, Centre National de la Recherche Scientifique (UPR 274), Villejuif, France
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