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Huang Z, Mai Z, Kong C, You J, Lin S, Gao C, Zhang W, Chen X, Xie Q, Wang H, Tang S, Zhou P, Gong L, Zhang G. African swine fever virus pB475L evades host antiviral innate immunity via targeting STAT2 to inhibit IFN-I signaling. J Biol Chem 2024; 300:107472. [PMID: 38879005 DOI: 10.1016/j.jbc.2024.107472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/16/2024] [Accepted: 06/07/2024] [Indexed: 07/08/2024] Open
Abstract
African swine fever virus (ASFV) causes severe disease in domestic pigs and wild boars, seriously threatening the development of the global pig industry. Type I interferon (IFN-I) is an important component of innate immunity, inducing the transcription and expression of antiviral cytokines by activating Janus-activated kinase-signal transducer and activator of transcription (STAT). However, the underlying molecular mechanisms by which ASFV antagonizes IFN-I signaling have not been fully elucidated. Therefore, using coimmunoprecipitation, confocal microscopy, and dual luciferase reporter assay methods, we investigated these mechanisms and identified a novel ASFV immunosuppressive protein, pB475L, which interacts with the C-terminal domain of STAT2. Consequently, pB475L inhibited IFN-I signaling by inhibiting STAT1 and STAT2 heterodimerization and nuclear translocation. Furthermore, we constructed an ASFV-B475L7PM mutant strain by homologous recombination, finding that ASFV-B475L7PM attenuated the inhibitory effects on IFN-I signaling compared to ASFV-WT. In summary, this study reveals a new mechanism by which ASFV impairs host innate immunity.
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Affiliation(s)
- Zhao Huang
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; Guangdong Provincial Key Laboratory of Utilization and Conservation of Food and Medicinal Resources in Northern Region, Shaoguan University, Shaoguan, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - Zhanzhuo Mai
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - Cuiying Kong
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Jianyi You
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - Sizhan Lin
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - Chenyang Gao
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - WenBo Zhang
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - Xiongnan Chen
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; Guangdong Provincial Key Laboratory of Utilization and Conservation of Food and Medicinal Resources in Northern Region, Shaoguan University, Shaoguan, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China
| | - Qingmei Xie
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Heng Wang
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China; Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou, China
| | - Shengqiu Tang
- Guangdong Provincial Key Laboratory of Utilization and Conservation of Food and Medicinal Resources in Northern Region, Shaoguan University, Shaoguan, China
| | - Pei Zhou
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China.
| | - Lang Gong
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; African Swine Fever Regional Laboratory of China, South China Agricultural University, Guangzhou, China.
| | - Guihong Zhang
- Key Laboratory of Zoonosis Prevention and Control of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China; Research Center for African Swine Fever Prevention and Control, South China Agricultural University, Guangzhou, China; Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong, China; Key Laboratory of Animal Vaccine Development, Ministry of Agriculture and Rural Affairs, Guangzhou, China.
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Mbanefo EC, Seifert A, Yadav MK, Yu CR, Nagarajan V, Parihar A, Singh S, Egwuagu CE. A Camelid-Derived STAT-Specific Nanobody Inhibits Neuroinflammation and Ameliorates Experimental Autoimmune Encephalomyelitis (EAE). Cells 2024; 13:1042. [PMID: 38920670 PMCID: PMC11201538 DOI: 10.3390/cells13121042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 05/25/2024] [Accepted: 06/14/2024] [Indexed: 06/27/2024] Open
Abstract
Proinflammatory T-lymphocytes recruited into the brain and spinal cord mediate multiple sclerosis (MS) and currently there is no cure for MS. IFN-γ-producing Th1 cells induce ascending paralysis in the spinal cord while IL-17-producing Th17 cells mediate cerebellar ataxia. STAT1 and STAT3 are required for Th1 and Th17 development, respectively, and the simultaneous targeting of STAT1 and STAT3 pathways is therefore a potential therapeutic strategy for suppressing disease in the spinal cord and brain. However, the pharmacological targeting of STAT1 and STAT3 presents significant challenges because of their intracellular localization. We have developed a STAT-specific single-domain nanobody (SBT-100) derived from camelids that targets conserved residues in Src homolog 2 (SH2) domains of STAT1 and STAT3. This study investigated whether SBT-100 could suppress experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We show that SBT-100 ameliorates encephalomyelitis through suppressing the expansion of Th17 and Th1 cells in the brain and spinal cord. Adoptive transfer experiments revealed that lymphocytes from SBT-100-treated EAE mice have reduced capacity to induce EAE, indicating that the immunosuppressive effects derived from the direct suppression of encephalitogenic T-cells. The small size of SBT-100 makes this STAT-specific nanobody a promising immunotherapy for CNS autoimmune diseases, including multiple sclerosis.
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Affiliation(s)
- Evaristus C. Mbanefo
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Allison Seifert
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Manoj Kumar Yadav
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Cheng-Rong Yu
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Vijayaraj Nagarajan
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | | | - Sunanda Singh
- Singh Biotechnology, 1547 Fox Grape Loop, Lutz, FL 33558, USA
| | - Charles E. Egwuagu
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
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Wang J, Batista VS, Bunick CG. Triple-action inhibitory mechanism of allosteric TYK2-specific inhibitors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561507. [PMID: 37873392 PMCID: PMC10592677 DOI: 10.1101/2023.10.09.561507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Deucravacitinib, 6-(cyclopropanecarbonylamido)-4-[2-methoxy-3-(1-methyl-1,2,4-triazol-3-yl)anilino]-N-(trideuteriomethyl)pyridazine-3-carboxamide, is a highly selective inhibitor of protein tyrosine kinase 2 (TYK2) that targets the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway. The structural basis for its selectivity and allosteric inhibition remains poorly understood. Here, we investigate the inhibition mechanism through analysis of available structures relevant to the STAT pathway, including crystal structures of the truncated TYK2 FERM-SH2 domain bound to the IFNα type I receptor (IFNαR1) and the truncated TYK2 JH2-JH1 domain. Our computational analysis provides a mechanistic hypothesis for the relatively rapid interferon-induced gene expression mediated by TYK2 relative to other cytokines. We find that deucravacitinib inhibits TYK2 kinase in three distinct states: the autoinhibited state and two activated states for autophosphorylation and phosphorylation of downstream protein substrates. Its binding to the TYK2 pseudokinase domain in the autoinhibited state restricts the essential dynamics of the TYK2 kinase domain required for kinase activity. Furthermore, it binds competitively with ATP in the pseudokinase domain, and also directly prevents formation of the active state of TYK2 through steric clashes.
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Affiliation(s)
- Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | | | - Christopher G. Bunick
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
- Department of Dermatology, Yale University, New Haven, CT06520, USA
- Program in Translational Biomedicine, Yale School of Medicine, New Haven, CT 06511, USA
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Mesev EV, Guare EG, Ploss A, Toettcher JE. Synthetic Heterodimers of Type III Interferon Receptors Require TYK2 for STAT Activation. J Interferon Cytokine Res 2023; 43:414-426. [PMID: 37725008 PMCID: PMC10517332 DOI: 10.1089/jir.2023.0039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 07/10/2023] [Indexed: 09/21/2023] Open
Abstract
Type III interferons (IFN-λ) are central to host defense against viral infection of epithelial barrier surfaces. IFN-λ binding to its receptor induces a JAK-STAT cascade through kinases Janus-associated kinase 1 (JAK1) and tyrosine kinase 2 (TYK2), which are associated on either subunit of the heterodimeric type III IFN receptor. Recent studies have shown that TYK2 is not necessary for IFN-λ to signal, in contrast to IFN-α, which uses the same JAK-STAT pathway activated by the type I IFN receptor. The mechanism for this differential TYK2 requirement is unknown. Our study uses synthetic IFN receptors in TYK2-deficient U2OS epithelial cells to define the processes in type I and III IFN signaling that require TYK2. We find that TYK2 deficiency reduces signaling equally from heterodimers of either type I or III IFN receptor intracellular domains. In contrast, JAK1-associated homodimers of IFNAR2 or IFNLR1 are both fully signaling competent even in the absence of TYK2. These results suggest that heterodimerization of the type III IFN receptor is insufficient to confer TYK2-independent signaling. Thus, we propose that noncanonical receptor complexes may participate in endogenous type III IFN signaling to confer TYK2-independent signaling downstream of IFN-λ stimulation.
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Affiliation(s)
- Emily V. Mesev
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Emma G. Guare
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Alexander Ploss
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Jared E. Toettcher
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, New Jersey, USA
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Riera E, García-Belmonte R, Madrid R, Pérez-Núñez D, Revilla Y. African swine fever virus ubiquitin-conjugating enzyme pI215L inhibits IFN-I signaling pathway through STAT2 degradation. Front Microbiol 2023; 13:1081035. [PMID: 36713190 PMCID: PMC9880986 DOI: 10.3389/fmicb.2022.1081035] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 12/20/2022] [Indexed: 01/15/2023] Open
Abstract
African swine fever virus (ASFV) is the causative agent of one of the most lethal diseases affecting domestic pig and wild boar, which is endangering the swine industry due to its rapid expansion. ASFV has developed different mechanisms to evade the host immune response, including inhibition of type I IFN (IFN-I) production and signaling, since IFN-I is a key element in the cellular antiviral response. Here, we report a novel mechanism of evasion of the IFN-I signaling pathway carried out by the ASFV ubiquitin-conjugating enzyme pI215L. Our data showed that pI215L inhibited IFN-stimulated response element (ISRE) activity and the consecutive mRNA induction of the IFN-stimulated genes ISG15 and IFIT1 through the ubiquitination and proteasomal degradation of STAT2. Additionally, by immunofluorescence, co-immunoprecipitation and nucleus-cytoplasm fractionation approaches, we have confirmed the interaction and colocalization of STAT2 and pI215L, in ectopic experiments and during ASFV infection. Moreover, expression of the catalytic mutant (I215L-C85A) did not inhibit the induction of ISG15 and IFIT1, nor the activity of ISRE. Furthermore, we confirmed that STAT2 degradation by pI215L is dependent on its catalytic activity, since expression of the pI215L-C85A mutant did not affect STAT2 levels, compared to the wild-type protein. Yet, our data reveal that the interaction of pI215L with STAT2 does not require the integrity of its catalytic domain since the pI215L-C85A mutant co-immunoprecipitates with STAT2. All these findings reveal, for the first time, the involvement of E2-ubiquitin-conjugating enzyme activity of pI215L in the immune response modulation.
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Affiliation(s)
- Elena Riera
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Raquel García-Belmonte
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Ricardo Madrid
- Bioassays SL, UAM, Madrid, Spain,Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Biology, UCM, Madrid, Spain
| | - Daniel Pérez-Núñez
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Yolanda Revilla
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain,*Correspondence: Yolanda Revilla, ✉
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Kenaston MW, Pham OH, Petit MJ, Shah PS. Transcriptomic profiling implicates PAF1 in both active and repressive immune regulatory networks. BMC Genomics 2022; 23:787. [PMID: 36451099 PMCID: PMC9713194 DOI: 10.1186/s12864-022-09013-6] [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: 05/20/2022] [Accepted: 11/14/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Sitting at the interface of gene expression and host-pathogen interaction, polymerase associated factor 1 complex (PAF1C) is a rising player in the innate immune response. The complex localizes to the nucleus and associates with chromatin to modulate RNA polymerase II (RNAPII) elongation of gene transcripts. Performing this function at both proximal and distal regulatory elements, PAF1C interacts with many host factors across such sites, along with several microbial proteins during infection. Therefore, translating the ubiquity of PAF1C into specific impacts on immune gene expression remains especially relevant. RESULTS Advancing past work, we treat PAF1 knockout cells with a slate of immune stimuli to identify key trends in PAF1-dependent gene expression with broad analytical depth. From our transcriptomic data, we confirm PAF1 is an activator of traditional immune response pathways as well as other cellular pathways correlated with pathogen defense. With this model, we employ computational approaches to refine how PAF1 may contribute to both gene activation and suppression. Specifically focusing on transcriptional motifs and regulons, we predict gene regulatory elements strongly associated with PAF1, including those implicated in an immune response. Overall, our results suggest PAF1 is involved in innate immunity at several distinct axes of regulation. CONCLUSIONS By identifying PAF1-dependent gene expression across several pathogenic contexts, we confirm PAF1C to be a key mediator of innate immunity. Combining these transcriptomic profiles with potential regulatory networks corroborates the previously identified functions of PAF1C. With this, we foster new avenues for its study as a regulator of innate immunity, and our results will serve as a basis for targeted study of PAF1C in future validation studies.
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Affiliation(s)
- Matthew W. Kenaston
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, USA
| | - Oanh H. Pham
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, USA
| | - Marine J. Petit
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, USA ,grid.301713.70000 0004 0393 3981MRC-University of Glasgow, Centre for Virus Research, G61 1HQ, Glasgow, UK
| | - Priya S. Shah
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, USA ,Department of Chemical Engineering, University of California, Davis, Davis, California, USA
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Kim JK, Han SB, Park SI, Kim IS, Kim DH. Nuclear transport of STAT6 determines the matrix rigidity dependent M2 activation of macrophages. Biomaterials 2022; 290:121859. [DOI: 10.1016/j.biomaterials.2022.121859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 10/04/2022] [Accepted: 10/09/2022] [Indexed: 11/28/2022]
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SARS-CoV-2 ORF6 disrupts nucleocytoplasmic trafficking to advance viral replication. Commun Biol 2022; 5:483. [PMID: 35590097 PMCID: PMC9120032 DOI: 10.1038/s42003-022-03427-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/29/2022] [Indexed: 11/08/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ORF6 is an antagonist of interferon (IFN)-mediated antiviral signaling, achieved through the prevention of STAT1 nuclear localization. However, the exact mechanism through which ORF6 prevents STAT1 nuclear trafficking remains unclear. Herein, we demonstrate that ORF6 directly binds to STAT1 with or without IFN stimulation, resulting in the nuclear exclusion of STAT1. ORF6 also recognizes importin α subtypes with different modes, in particular, high affinity to importin α1 but a low affinity to importin α5. Although ORF6 potentially disrupts the importin α/importin β1-mediated nuclear transport, thereby suppressing the nuclear translocation of the other classical nuclear localization signal-containing cargo proteins, the inhibitory effect of ORF6 is modest when compared with that of STAT1. The results indicate that the drastic nuclear exclusion of STAT1 is attributed to the specific binding with ORF6, which is a distinct strategy for the importin α1-mediated pathway. Combined with the results from a newly-produced replicon system and a hamster model, we conclude that SARS-CoV-2 ORF6 acts as a virulence factor via regulation of nucleocytoplasmic trafficking to accelerate viral replication, resulting in disease progression.
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Infectious Bronchitis Virus Nsp14 Degrades JAK1 to Inhibit the JAK-STAT Signaling Pathway in HD11 Cells. Viruses 2022; 14:v14051045. [PMID: 35632786 PMCID: PMC9146749 DOI: 10.3390/v14051045] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/04/2022] [Accepted: 05/12/2022] [Indexed: 12/24/2022] Open
Abstract
Coronaviruses (CoVs) are RNA viruses that can infect a wide range of animals, including humans, and cause severe respiratory and gastrointestinal disease. The Gammacoronavirus avian infectious bronchitis virus (IBV) causes acute and contagious diseases in chickens, leading to severe economic losses. Nonstructural protein 14 (Nsp14) is a nonstructural protein encoded by the CoV genome. This protein has a regulatory role in viral virulence and replication. However, the function and mechanism of IBV Nsp14 in regulating the host’s innate immune response remain unclear. Here we report that IBV Nsp14 was a JAK-STAT signaling pathway antagonist in chicken macrophage (HD11) cells. In these cells, Nsp14 protein overexpression blocked IBV suppression induced by exogenous chIFN-γ treatment. Meanwhile, Nsp14 remarkably reduced interferon-gamma-activated sequence (GAS) promoter activation and chIFN-γ-induced interferon-stimulated gene expression. Nsp14 impaired the nuclear translocation of chSTAT1. Furthermore, Nsp14 interacted with Janus kinase 1 (JAK1) to degrade JAK1 via the autophagy pathway, thereby preventing the activation of the JAK-STAT signaling pathway and facilitating viral replication. These results indicated a novel mechanism by which IBV inhibits the host antiviral response and provide new insights into the selection of antiviral targets against CoV.
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Menon PR, Staab J, Gregus A, Wirths O, Meyer T. An inhibitory effect on the nuclear accumulation of phospho-STAT1 by its unphosphorylated form. Cell Commun Signal 2022; 20:42. [PMID: 35361236 PMCID: PMC8974011 DOI: 10.1186/s12964-022-00841-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Unphosphorylated signal transducer and activator of transcription 1 (U-STAT1) has been reported to elicit a distinct gene expression profile as compared to tyrosine-phosphorylated STAT1 (P-STAT1) homodimers. However, the impact of U-STAT1 on the IFNγ-induced immune response mediated by P-STAT1 is unknown. By generating a double mutant of STAT1 with mutation R602L in the Src-homology 2 (SH2) domain and Y701F in the carboxy-terminal transactivation domain mimicking U-STAT1, we investigated the effects of U-STAT1 on P-STAT1-mediated signal transduction. RESULTS In this study, we discovered a novel activity of U-STAT1 that alters the nucleo-cytoplasmic distribution of cytokine-stimulated P-STAT1. While the dimerization-deficient mutant R602L/Y701F was not able to display cytokine-induced nuclear accumulation, it inhibited the nuclear accumulation of co-expressed IFNγ-stimulated wild-type P-STAT1. Disruption of the anti-parallel dimer interface in the R602L/Y701F mutant via additional R274W and T385A mutations did not rescue the impaired nuclear accumulation of co-expressed P-STAT1. The mutant U-STAT1 affected neither the binding of co-expressed P-STAT1 to gamma-activated sites in vitro, nor the transcription of reporter constructs and the activation of STAT1 target genes. However, the nuclear accumulation of P-STAT1 was diminished in the presence of mutant U-STAT1, which was not restored by mutations reducing the DNA affinity of mutant U-STAT1. Whereas single mutations in the amino-terminus of dimerization-deficient U-STAT1 similarly inhibited the nuclear accumulation of co-expressed P-STAT1, a complete deletion of the amino-terminus restored cytokine-stimulated nuclear accumulation of P-STAT1. Likewise, the disruption of a dimer-specific nuclear localization signal also rescued the U-STAT1-mediated inhibition of P-STAT1 nuclear accumulation. CONCLUSION Our data demonstrate a novel role of U-STAT1 in affecting nuclear accumulation of P-STAT1, such that a high intracellular concentration of U-STAT1 inhibits the detection of nuclear P-STAT1 in immunofluorescence assays. These observations hint at a possible physiological function of U-STAT1 in buffering the nuclear import of P-STAT1, while preserving IFNγ-induced gene expression. Based on these results, we propose a model of a hypothetical import structure, the assembly of which is impaired under high concentrations of U-STAT1. This mechanism maintains high levels of cytoplasmic STAT1, while simultaneously retaining signal transduction by IFNγ. Video Abstract.
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Affiliation(s)
- Priyanka Rajeev Menon
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Centre Göttingen, and German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
| | - Julia Staab
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Centre Göttingen, and German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
| | - Anke Gregus
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Centre Göttingen, and German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
| | - Oliver Wirths
- Department of Psychiatry and Psychotherapy, University Medical Centre Göttingen, Göttingen, Germany
| | - Thomas Meyer
- Department of Psychosomatic Medicine and Psychotherapy, University Medical Centre Göttingen, and German Centre for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany.
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Histone deacetylase 3 contributes to the antiviral innate immunity of macrophages by interacting with FOXK1 to regulate STAT1/2 transcription. Cell Rep 2022; 38:110302. [PMID: 35081346 DOI: 10.1016/j.celrep.2022.110302] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 11/16/2021] [Accepted: 01/05/2022] [Indexed: 12/15/2022] Open
Abstract
It is well known that interferon (IFN)-α/-β activates the JAK/STAT signaling pathway and suppresses viral replication through the induction of IFN stimulated genes (ISGs). Here, we report that knockout of HDAC3 from macrophages results in the decreased expression of STAT1 and STAT2, leading to defective antiviral immunity in cells and mice. Further studies show that HDAC3 interacts with a conserved transcription factor Forkhead Box K1 (FOXK1), co-localizes with FOXK1 at the promoter of STAT1 and STAT2, and is required for protecting FOXK1 from lysosomal system-mediated degradation. FOXK1-deficient macrophages also show low STAT1 and STAT2 expression with defective responses to viruses. Thus, our studies uncover the biological importance of HDAC3 in regulating the antiviral immunity of macrophages through interacting with FOXK1 to regulate the expression of STAT1 and STAT2.
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12
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Cheng D, Semmens K, McManus E, Chen Q, Meerzaman D, Wang X, Hafner M, Lewis BA, Takahashi H, Devaiah BN, Gegonne A, Singer DS. The nuclear transcription factor, TAF7, is a cytoplasmic regulator of protein synthesis. SCIENCE ADVANCES 2021; 7:eabi5751. [PMID: 34890234 PMCID: PMC8664259 DOI: 10.1126/sciadv.abi5751] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
The TFIID component, TAF7, has been extensively characterized as essential for transcription and is critical for cell proliferation and differentiation. Here, we report that TAF7 is a previously unknown RNA chaperone that contributes to the regulation of protein synthesis. Mechanistically, TAF7 binds RNAs in the nucleus and delivers them to cytoplasmic polysomes. A broad spectrum of target RNA species, including the HIV-1 transactivation response element, binds TAF7 through consensus CUG motifs within the 3′ untranslated region. Export to the cytoplasm depends on a TAF7 nuclear export signal and occurs by an exportin 1–dependent pathway. Notably, disrupting either TAF7’s RNA binding or its export from the nucleus results in retention of target messenger RNAs in the nucleus and reduced levels of the protein products of TAF7-target RNAs. Thus, TAF7, an essential transcription factor, plays a key role in the regulation of RNA translation, thereby potentially connecting these processes.
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Affiliation(s)
- Dan Cheng
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Kevin Semmens
- School of Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | - Elizabeth McManus
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Qingrong Chen
- Center for Biomedical Informatics and Information Technology, National Cancer Institute, NIH, Rockville, MD 20850, USA
| | - Daoud Meerzaman
- Center for Biomedical Informatics and Information Technology, National Cancer Institute, NIH, Rockville, MD 20850, USA
| | - Xiantao Wang
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD 20892, USA
| | - Markus Hafner
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD 20892, USA
| | - Brian A. Lewis
- Laboratory of Pathology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Hidehisa Takahashi
- Department of Molecular Biology, Yokohama City University Graduate School of Medical Science, Fukuura 3-9, Kanazawa-ku, Yokohama, Kanagawa 216-0004, Japan
| | | | - Anne Gegonne
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Dinah S. Singer
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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13
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Riera E, Pérez-Núñez D, García-Belmonte R, Miorin L, García-Sastre A, Revilla Y. African Swine Fever Virus Induces STAT1 and STAT2 Degradation to Counteract IFN-I Signaling. Front Microbiol 2021; 12:722952. [PMID: 34512601 PMCID: PMC8427279 DOI: 10.3389/fmicb.2021.722952] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/05/2021] [Indexed: 12/24/2022] Open
Abstract
African swine fever virus (ASFV) causes a serious disease in domestic pigs and wild boars and is currently expanding worldwide. No safe and efficacious vaccines against ASFV are available, which threats the swine industry worldwide. African swine fever virus (ASFV) is a complex dsDNA virus that displays multiple mechanisms to counteract the host innate immune response, whose efficacy might determine the different degrees of virulence displayed by attenuated and virulent ASFV strains. Here we report that infection with both virulent Arm/07/CBM/c2 and attenuated NH/P68 strains prevents interferon-stimulated gene (ISG) expression in interferon (IFN)-treated cells by counteracting the JAK/STAT pathway. This inhibition results in an impaired nuclear translocation of the interferon-stimulated gene factor 3 (ISGF3) complex, as well as in the proteasome-dependent STAT2 degradation and caspase 3-dependent STAT1 cleavage. The existence of two independent mechanisms of control of the JAK/STAT pathway, suggests the importance of preventing this pathway for successful viral replication. As ASFV virulence is likely associated with the efficacy of the IFN signaling inhibitory mechanisms, a better understanding of these IFN antagonistic properties may lead to new strategies to control this devastating pig disease.
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Affiliation(s)
- Elena Riera
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/Nicolás Cabrera, Madrid, Spain
| | - Daniel Pérez-Núñez
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/Nicolás Cabrera, Madrid, Spain
| | - Raquel García-Belmonte
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/Nicolás Cabrera, Madrid, Spain
| | - Lisa Miorin
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Icahn School of Medicine at Mount Sinai, Global Health and Emergent Pathogens Institute, New York, NY, United States
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Icahn School of Medicine at Mount Sinai, Global Health and Emergent Pathogens Institute, New York, NY, United States.,Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Icahn School of Medicine at Mount Sinai, The Tisch Cancer Institute, New York, NY, United States.,Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Yolanda Revilla
- Microbes in Health and Welfare Department, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/Nicolás Cabrera, Madrid, Spain
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14
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Lang YD, Jou YS. PSPC1 is a new contextual determinant of aberrant subcellular translocation of oncogenes in tumor progression. J Biomed Sci 2021; 28:57. [PMID: 34340703 PMCID: PMC8327449 DOI: 10.1186/s12929-021-00753-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/24/2021] [Indexed: 12/30/2022] Open
Abstract
Dysregulation of nucleocytoplasmic shuttling is commonly observed in cancers and emerging as a cancer hallmark for the development of anticancer therapeutic strategies. Despite its severe adverse effects, selinexor, a selective first-in-class inhibitor of the common nuclear export receptor XPO1, was developed to target nucleocytoplasmic protein shuttling and received accelerated FDA approval in 2019 in combination with dexamethasone as a fifth-line therapeutic option for adults with relapsed refractory multiple myeloma (RRMM). To explore innovative targets in nucleocytoplasmic shuttling, we propose that the aberrant contextual determinants of nucleocytoplasmic shuttling, such as PSPC1 (Paraspeckle component 1), TGIF1 (TGF-β Induced Factor Homeobox 1), NPM1 (Nucleophosmin), Mortalin and EBP50, that modulate shuttling (or cargo) proteins with opposite tumorigenic functions in different subcellular locations could be theranostic targets for developing anticancer strategies. For instance, PSPC1 was recently shown to be the contextual determinant of the TGF-β prometastatic switch and PTK6/β-catenin reciprocal oncogenic nucleocytoplasmic shuttling during hepatocellular carcinoma (HCC) progression. The innovative nucleocytoplasmic shuttling inhibitor PSPC1 C-terminal 131 polypeptide (PSPC1-CT131), which was developed to target both the shuttling determinant PSPC1 and the shuttling protein PTK6, maintained their tumor-suppressive characteristics and exhibited synergistic effects on tumor suppression in HCC cells and mouse models. In summary, targeting the contextual determinants of nucleocytoplasmic shuttling with cargo proteins having opposite tumorigenic functions in different subcellular locations could be an innovative strategy for developing new therapeutic biomarkers and agents to improve cancer therapy.
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Affiliation(s)
- Yaw-Dong Lang
- Institute of Biomedical Sciences, Academia Sinica, 11529, Taipei, Taiwan
| | - Yuh-Shan Jou
- Institute of Biomedical Sciences, Academia Sinica, 11529, Taipei, Taiwan.
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15
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Diallo M, Herrera F. The role of understudied post-translational modifications for the behavior and function of Signal Transducer and Activator of Transcription 3. FEBS J 2021; 289:6235-6255. [PMID: 34235865 DOI: 10.1111/febs.16116] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 06/16/2021] [Accepted: 07/07/2021] [Indexed: 12/19/2022]
Abstract
The Signal Transducer and Activator of Transcription (STAT) family of transcription factors is involved in inflammation, immunity, development, cancer, and response to injury, among other biological phenomena. Canonical STAT signaling is often represented as a 3-step pathway involving the sequential activation of a membrane receptor, an intermediate kinase, and a STAT transcription factor. The rate-limiting phosphorylation at a highly conserved C-terminal tyrosine residue determines the nuclear translocation and transcriptional activity of STATs. This apparent simplicity is actually misleading and can hardly explain the pleiotropic nature of STATs, the existence of various noncanonical STAT pathways, or the key role of the N-terminal domain in STAT functions. More than 80 post-translational modifications (PTMs) have been identified for STAT3, but their functions remain barely understood. Here, we provide a brief but comprehensive overview of these underexplored PTMs and their role on STAT3 canonical and noncanonical functions. A less tyrosine-centric point of view may be required to advance our understanding of STAT signaling.
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Affiliation(s)
- Mickael Diallo
- Faculdade de Ciências da Universidade de Lisboa, Cell Structure and Dynamics Laboratory, BioISI - Instituto de Biosistemas e Ciências integrativas, Lisbon, Portugal.,MOSTMICRO Research Unit, Instituto de Tecnologia Química e Biológica (ITQB-NOVA), Universidade Nova de Lisboa, Oeiras, Portugal
| | - Federico Herrera
- Faculdade de Ciências da Universidade de Lisboa, Cell Structure and Dynamics Laboratory, BioISI - Instituto de Biosistemas e Ciências integrativas, Lisbon, Portugal.,MOSTMICRO Research Unit, Instituto de Tecnologia Química e Biológica (ITQB-NOVA), Universidade Nova de Lisboa, Oeiras, Portugal
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16
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Shen Q, Wang YE, Palazzo AF. Crosstalk between nucleocytoplasmic trafficking and the innate immune response to viral infection. J Biol Chem 2021; 297:100856. [PMID: 34097873 PMCID: PMC8254040 DOI: 10.1016/j.jbc.2021.100856] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/24/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
The nuclear pore complex is the sole gateway connecting the nucleoplasm and cytoplasm. In humans, the nuclear pore complex is one of the largest multiprotein assemblies in the cell, with a molecular mass of ∼110 MDa and consisting of 8 to 64 copies of about 34 different nuclear pore proteins, termed nucleoporins, for a total of 1000 subunits per pore. Trafficking events across the nuclear pore are mediated by nuclear transport receptors and are highly regulated. The nuclear pore complex is also used by several RNA viruses and almost all DNA viruses to access the host cell nucleoplasm for replication. Viruses hijack the nuclear pore complex, and nuclear transport receptors, to access the nucleoplasm where they replicate. In addition, the nuclear pore complex is used by the cell innate immune system, a network of signal transduction pathways that coordinates the first response to foreign invaders, including viruses and other pathogens. Several branches of this response depend on dynamic signaling events that involve the nuclear translocation of downstream signal transducers. Mounting evidence has shown that these signaling cascades, especially those steps that involve nucleocytoplasmic trafficking events, are targeted by viruses so that they can evade the innate immune system. This review summarizes how nuclear pore proteins and nuclear transport receptors contribute to the innate immune response and highlights how viruses manipulate this cellular machinery to favor infection. A comprehensive understanding of nuclear pore proteins in antiviral innate immunity will likely contribute to the development of new antiviral therapeutic strategies.
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Affiliation(s)
- Qingtang Shen
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.
| | - Yifan E Wang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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17
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Lu J, Wu T, Zhang B, Liu S, Song W, Qiao J, Ruan H. Types of nuclear localization signals and mechanisms of protein import into the nucleus. Cell Commun Signal 2021; 19:60. [PMID: 34022911 PMCID: PMC8140498 DOI: 10.1186/s12964-021-00741-y] [Citation(s) in RCA: 148] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 04/16/2021] [Indexed: 12/28/2022] Open
Abstract
Nuclear localization signals (NLS) are generally short peptides that act as a signal fragment that mediates the transport of proteins from the cytoplasm into the nucleus. This NLS-dependent protein recognition, a process necessary for cargo proteins to pass the nuclear envelope through the nuclear pore complex, is facilitated by members of the importin superfamily. Here, we summarized the types of NLS, focused on the recently reported related proteins containing nuclear localization signals, and briefly summarized some mechanisms that do not depend on nuclear localization signals into the nucleus. Video Abstract.
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Affiliation(s)
- Juane Lu
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Tao Wu
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Biao Zhang
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Suke Liu
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Wenjun Song
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Jianjun Qiao
- Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, China
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
| | - Haihua Ruan
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
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18
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Liu H, Giffen KP, Grati M, Morrill SW, Li Y, Liu X, Briegel KJ, He DZ. Transcription co-factor LBH is necessary for the survival of cochlear hair cells. J Cell Sci 2021; 134:237781. [PMID: 33674448 DOI: 10.1242/jcs.254458] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 02/11/2021] [Indexed: 11/20/2022] Open
Abstract
Hearing loss affects ∼10% of adults worldwide. Most sensorineural hearing loss is caused by the progressive loss of mechanosensitive hair cells (HCs) in the cochlea. The molecular mechanisms underlying HC maintenance and loss remain poorly understood. LBH, a transcription co-factor implicated in development, is abundantly expressed in outer hair cells (OHCs). We used Lbh-null mice to identify its role in HCs. Surprisingly, Lbh deletion did not affect differentiation and the early development of HCs, as nascent HCs in Lbh knockout mice had normal looking stereocilia. The stereocilia bundle was mechanosensitive and OHCs exhibited the characteristic electromotility. However, Lbh-null mice displayed progressive hearing loss, with stereocilia bundle degeneration and OHC loss as early as postnatal day 12. RNA-seq analysis showed significant gene enrichment of biological processes related to transcriptional regulation, cell cycle, DNA damage/repair and autophagy in Lbh-null OHCs. In addition, Wnt and Notch pathway-related genes were found to be dysregulated in Lbh-deficient OHCs. Our study implicates, for the first time, loss of LBH function in progressive hearing loss, and demonstrates a critical requirement of LBH in promoting HC survival in adult mice.
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Affiliation(s)
- Huizhan Liu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Kimberlee P Giffen
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - M'Hamed Grati
- Department of Otorhinolaryngology-Head and Neck Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Seth W Morrill
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA
| | - Yi Li
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA.,Department of Otorhinolaryngology-Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, 100730 Beijing, China
| | - Xuezhong Liu
- Department of Otorhinolaryngology-Head and Neck Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Karoline J Briegel
- Department of Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - David Z He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA
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19
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Price RM, Budzyński MA, Kundra S, Teves SS. Advances in visualizing transcription factor - DNA interactions. Genome 2020; 64:449-466. [PMID: 33113335 DOI: 10.1139/gen-2020-0086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
At the heart of the transcription process is the specific interaction between transcription factors (TFs) and their target DNA sequences. Decades of molecular biology research have led to unprecedented insights into how TFs access the genome to regulate transcription. In the last 20 years, advances in microscopy have enabled scientists to add imaging as a powerful tool in probing two specific aspects of TF-DNA interactions: structure and dynamics. In this review, we examine how applications of diverse imaging technologies can provide structural and dynamic information that complements insights gained from molecular biology assays. As a case study, we discuss how applications of advanced imaging techniques have reshaped our understanding of TF behavior across the cell cycle, leading to a rethinking in the field of mitotic bookmarking.
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Affiliation(s)
- Rachel M Price
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.,Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Marek A Budzyński
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.,Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Shivani Kundra
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.,Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Sheila S Teves
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.,Department of Biochemistry and Molecular Biology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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20
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SARS-CoV-2 Orf6 hijacks Nup98 to block STAT nuclear import and antagonize interferon signaling. Proc Natl Acad Sci U S A 2020; 117:28344-28354. [PMID: 33097660 PMCID: PMC7668094 DOI: 10.1073/pnas.2016650117] [Citation(s) in RCA: 362] [Impact Index Per Article: 90.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic that is a serious global health problem. Evasion of IFN-mediated antiviral signaling is a common defense strategy that pathogenic viruses use to replicate and propagate in their host. In this study, we show that SARS-CoV-2 is able to efficiently block STAT1 and STAT2 nuclear translocation in order to impair transcriptional induction of IFN-stimulated genes (ISGs). Our results demonstrate that the viral accessory protein Orf6 exerts this anti-IFN activity. We found that SARS-CoV-2 Orf6 localizes at the nuclear pore complex (NPC) and directly interacts with Nup98-Rae1 via its C-terminal domain to impair docking of cargo-receptor (karyopherin/importin) complex and disrupt nuclear import. In addition, we show that a methionine-to-arginine substitution at residue 58 impairs Orf6 binding to the Nup98-Rae1 complex and abolishes its IFN antagonistic function. All together our data unravel a mechanism of viral antagonism in which a virus hijacks the Nup98-Rae1 complex to overcome the antiviral action of IFN.
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21
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Oladipupo FO, Yu CR, Olumuyide E, Jittaysothorn Y, Choi JK, Egwuagu CE. STAT3 deficiency in B cells exacerbates uveitis by promoting expansion of pathogenic lymphocytes and suppressing regulatory B cells (Bregs) and Tregs. Sci Rep 2020; 10:16188. [PMID: 33004854 PMCID: PMC7529787 DOI: 10.1038/s41598-020-73093-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
STAT3 transcription factor induces differentiation of naïve T cells into Th17 cells and loss of STAT3 in T cell prevents development of CNS autoimmune diseases. However, function of STAT3 in the B lymphocyte subset is not well understood. In this study, we have generated mice lacking STAT3 in CD19+ B cells (CD19-STAT3KO) and investigated intrinsic and extrinsic functions of STAT3 in B cells and its potential role in resistance or pathogenesis of organ-specific autoimmune diseases. We show that STAT3 regulates metabolic mechanisms in B cells with implications for bioenergetic and metabolic pathways that control cellular homeostasis in B cells. Thus, loss of STAT3 in CD19-STAT3KO cells perturbed growth and apoptosis by inducing rapid entry of B cells into the S-phase of the cell cycle, decreasing expression of cyclin-dependent kinase inhibitors and upregulating pro-apoptotic proteins. We further show that the CD19-STAT3KO mice develop severe experimental autoimmune uveitis (EAU), an animal model of human uveitis. Exacerbated uveitis in CD19-STAT3KO mice derived in part from enhanced expression of costimulatory molecules on B cells, marked increase of Th17 responses and increased recruitment of granulocytes into the neuroretina. The enhanced autoimmunity upon deletion of STAT3 in B cells is also recapitulated in experimental autoimmune encephalitis, a mouse model of multiple sclerosis and thus support our conclusion that STAT3 deletion in B cells enhanced inflammation and the effects observed are not model specific. Our data further indicate that STAT3 pathway modulates interactions between B and T cells during EAU resulting in alteration of lymphocyte repertoire by increasing levels of autoreactive pathogenic T cells while suppressing development and/or expansion of immune-suppressive lymphocytes (Bregs and Tregs). Taken together, STAT3 exerts diametrically opposite effects in lymphocytes, with loss of STAT3 in B cells exacerbating uveitis whereas Stat3 deletion in T cells confers protection.
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Affiliation(s)
- Favour O Oladipupo
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Building 10, Room 10N248G, 10 Center Drive, Bethesda, MD, 20892-1857, USA
| | - Cheng-Rong Yu
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Building 10, Room 10N248G, 10 Center Drive, Bethesda, MD, 20892-1857, USA
| | - Ezekiel Olumuyide
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Building 10, Room 10N248G, 10 Center Drive, Bethesda, MD, 20892-1857, USA
| | | | - Jin Kyeong Choi
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Building 10, Room 10N248G, 10 Center Drive, Bethesda, MD, 20892-1857, USA.,Department of Immunology, Jeonbuk National University Medical School, Jeonju, Jeonbuk, 54896, Republic of Korea
| | - Charles E Egwuagu
- Molecular Immunology Section, Laboratory of Immunology, National Eye Institute (NEI), National Institutes of Health (NIH), Building 10, Room 10N248G, 10 Center Drive, Bethesda, MD, 20892-1857, USA.
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22
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Stat2 stability regulation: an intersection between immunity and carcinogenesis. Exp Mol Med 2020; 52:1526-1536. [PMID: 32973222 PMCID: PMC8080578 DOI: 10.1038/s12276-020-00506-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 11/18/2022] Open
Abstract
Signal transducer and activator of transcription (STAT2) is a member of the STAT family that plays an essential role in immune responses to extracellular and intracellular stimuli, including inflammatory reactions, invasion of foreign materials, and cancer initiation. Although the majority of STAT2 studies in the last few decades have focused on interferon (IFN)-α/β (IFNα/β) signaling pathway-mediated host defense against viral infections, recent studies have revealed that STAT2 also plays an important role in human cancer development. Notably, strategic research on STAT2 function has provided evidence that transient regulatory activity by homo- or heterodimerization induces its nuclear localization where it to forms a ternary IFN-stimulated gene factor 3 (ISGF3) complex, which is composed of STAT1 and/or STAT2 and IFN regulatory factor 9 (IEF9). The molecular mechanisms of ISGF3-mediated ISG gene expression provide the basic foundation for the regulation of STAT2 protein activity but not protein quality control. Recently, previously unknown molecular mechanisms of STAT2-mediated cell proliferation via STAT2 protein quality control were elucidated. In this review, we briefly summarize the role of STAT2 in immune responses and carcinogenesis with respect to the molecular mechanisms of STAT2 stability regulation via the proteasomal degradation pathway. The activity of STAT2, a protein stimulated by molecular signalling systems to activate selected genes in ways that can lead to cancer, is regulated by factors controlling its rate of degradation. Yong-Yeon Cho and colleagues at The Catholic University of Korea in South Korea review the role of STAT2 in links between molecular signals of the immune response and the onset of cancer. They focus on the significance of factors that regulate the stability of STAT2. One key factor appears to be the molecular mechanisms controlling the degradation of STAT2 by cellular structures called proteasomes. These structures break down proteins as part of routine cell maintenance. Deeper understanding of the stimulation, action and degradation of STAT2 will assist efforts to treat the many cancers in which STAT2 activity is involved.
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23
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Piao JY, Kim SJ, Kim DH, Park JH, Park SA, Han HJ, Na HK, Yoon K, Lee HN, Kim N, Hahm KB, Surh YJ. Helicobacter pylori infection induces STAT3 phosphorylation on Ser727 and autophagy in human gastric epithelial cells and mouse stomach. Sci Rep 2020; 10:15711. [PMID: 32973302 PMCID: PMC7519032 DOI: 10.1038/s41598-020-72594-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 08/31/2020] [Indexed: 01/05/2023] Open
Abstract
Helicobacter pylori (H. pylori) infection is considered as one of the principal risk factors of gastric cancer. Constitutive activation of the signal transducer and activator of transcription 3 (STAT3) plays an important role in inflammation-associated gastric carcinogenesis. In the canonical STAT3 pathway, phosphorylation of STAT3 on Tyr705 is a major event of STAT3 activation. However, recent studies have demonstrated that STAT3 phosphorylated on Ser727 has an independent function in mitochondria. In the present study, we found that human gastric epithelial AGS cells infected with H. pylori resulted in localization of STAT3 phosphorylated on Ser727 (P-STAT3Ser727), predominantly in the mitochondria. Notably, H. pylori-infected AGS cells exhibited the loss of mitochondrial integrity and increased expression of the microtubule-associated protein light chain 3 (LC3), the autophagosomal membrane-associated protein. Treatment of AGS cells with a mitophagy inducer, carbonyl cyanide 3-chlorophenylhydrazone (CCCP), resulted in accumulation of P-STAT3Ser727 in mitochondria. In addition, the elevated expression and mitochondrial localization of LC3 induced by H. pylori infection were attenuated in AGS cells harboring STAT3 mutation defective in Ser727 phosphorylation (S727A). We also observed that both P-STAT3Ser727 expression and LC3 accumulation were increased in the mitochondria of H. pylori-inoculated mouse stomach.
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Affiliation(s)
- Juan-Yu Piao
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea
| | - Su-Jung Kim
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea
| | - Do-Hee Kim
- Department of Chemistry, College of Convergence and Integrated Science, Kyonggi University, Suwon, Gyeonggi-do, 16227, South Korea
| | - Ji Hyun Park
- Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Sin-Aye Park
- Department of Biomedical Laboratory Science, College of Medical Sciences, Soonchunhyang University, Asan, 31538, South Korea
| | - Hyeong-Jun Han
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea
| | - Hye-Kyung Na
- Department of Food Science and Biotechnology, College of Knowledge-Based Services Engineering, Sungshin Women's University, Seoul, 01133, South Korea
| | - Kichul Yoon
- Department of Internal Medicine and Digestive Disease Research Institute, Wonkwang University Sanbon Hospital, Gunpo, Gyeonggi-do, 15865, South Korea
| | - Ha-Na Lee
- Laboratory of Immunology, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Nayoung Kim
- Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, 03080, South Korea
| | - Ki Baik Hahm
- Digestive Disease Center, CHA University Bundang Medical Center, Seongnam, Gyunggi-do, 13496, South Korea
| | - Young-Joon Surh
- Tumor Microenvironment Global Core Research Center, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea. .,Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, South Korea.
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24
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Trofimov K, Ivanov R, Eutebach M, Acaroglu B, Mohr I, Bauer P, Brumbarova T. Mobility and localization of the iron deficiency-induced transcription factor bHLH039 change in the presence of FIT. PLANT DIRECT 2019; 3:e00190. [PMID: 31879716 PMCID: PMC6927231 DOI: 10.1002/pld3.190] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 05/03/2023]
Abstract
Regulation of iron (Fe) acquisition and homeostasis is critical for plant survival. In Arabidopsis, Fe deficiency-induced bHLH039 forms a complex with the master regulator FIT and activates it to upregulate Fe acquisition genes. FIT is partitioned between cytoplasm and nucleus, whereby active FIT accumulates more in the nucleus than inactive FIT. At the same time, there is so far no information on the subcellular localization of bHLH039 protein and how it is controlled. We report here that the bHLH039 localization pattern changes depending on the presence of FIT in the cell. When expressed in cells lacking FIT, bHLH039 localizes predominantly in the cytoplasm, including cytoplasmic foci in close proximity to the plasma membrane. The presence of FIT enhances the mobility of bHLH039 and redirects the protein toward primarily nuclear localization, abolishing its accumulation in cytoplasmic foci. This FIT-dependent change in localization of bHLH039 found in transient fluorescent protein expression experiments was confirmed in both leaves and roots of Arabidopsis transgenic plants, stably expressing hemagglutinin-tagged bHLH039 in wild-type or fit mutant background. This posttranslational mechanism for intracellular partitioning of Fe-responsive transcription factors suggests a signaling cascade that translates Fe sensing at the plasma membrane to nuclear accumulation of the transcriptional regulators.
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Affiliation(s)
- Ksenia Trofimov
- Institute of BotanyHeinrich Heine UniversityDüsseldorfGermany
| | - Rumen Ivanov
- Institute of BotanyHeinrich Heine UniversityDüsseldorfGermany
| | | | - Büsra Acaroglu
- Institute of BotanyHeinrich Heine UniversityDüsseldorfGermany
| | - Inga Mohr
- Institute of BotanyHeinrich Heine UniversityDüsseldorfGermany
| | - Petra Bauer
- Institute of BotanyHeinrich Heine UniversityDüsseldorfGermany
- Cluster of Excellence on Plant SciencesHeinrich Heine UniversityDüsseldorfGermany
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25
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Lee KM, Park KH, Hwang JS, Lee M, Yoon DS, Ryu HA, Jung HS, Park KW, Kim J, Park SW, Kim SH, Chun YM, Choi WJ, Lee JW. Inhibition of STAT5A promotes osteogenesis by DLX5 regulation. Cell Death Dis 2018; 9:1136. [PMID: 30429452 PMCID: PMC6235898 DOI: 10.1038/s41419-018-1184-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/19/2018] [Accepted: 10/24/2018] [Indexed: 12/13/2022]
Abstract
The regulation of osteogenesis is important for bone formation and fracture healing. Despite advances in understanding the molecular mechanisms of osteogenesis, crucial modulators in this process are not well-characterized. Here we demonstrate that suppression of signal transducer and activator of transcription 5A (STAT5A) activates distal-less homeobox 5 (DLX5) in human bone marrow-derived stromal cells (hBMSCs) and enhances osteogenesis in vitro and in vivo. We show that STAT5A negatively regulates expression of Dlx5 in vitro and that STAT5A deletion results in increased trabecular and cortical bone mass and bone mineral density in mice. Additionally, STAT5A deletion prevents age-related bone loss. In a murine fracture model, STAT5A deletion was found to significantly enhance bone remodeling by stimulating the formation of a fracture callus. Our findings indicate that STAT5A inhibition enhances bone formation by promoting osteogenesis of BMSCs.
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Affiliation(s)
- Kyoung-Mi Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea.,Severance Biomedical Science Institute, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Kwang Hwan Park
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Ji Suk Hwang
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Moses Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Dong Suk Yoon
- Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC, 27834, USA
| | - Hyun Aae Ryu
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Ho Sun Jung
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Ki Won Park
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Jihyun Kim
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea.,Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Sahng Wook Park
- Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Integrated Genomic Research Center for Metabolic Regulation, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Sung-Hwan Kim
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Yong-Min Chun
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Woo Jin Choi
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Jin Woo Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea. .,Severance Biomedical Science Institute, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea. .,Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.
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26
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Kitagawa Y, Sakai M, Shimojima M, Saijo M, Itoh M, Gotoh B. Nonstructural protein of severe fever with thrombocytopenia syndrome phlebovirus targets STAT2 and not STAT1 to inhibit type I interferon-stimulated JAK-STAT signaling. Microbes Infect 2018; 20:360-368. [PMID: 29886262 DOI: 10.1016/j.micinf.2018.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/17/2023]
Abstract
The nonstructural protein NSs of severe fever with thrombocytopenia syndrome phlebovirus blocks type I interferon (IFN)-stimulated JAK-STAT signaling. However, there is continuing controversy as to whether NSs targets STAT1 or STAT2 or both for this blockade. The present study was designed to gain a further understanding of the blockade mechanism. Immunoprecipitation experiments revealed a stronger interaction of NSs with STAT2 than with any other component constituting the JAK-STAT pathway. Expression of NSs resulted in the formation of cytoplasmic inclusion bodies (IBs), and affected cytoplasmic distribution of STAT2. STAT2 was relocated to NSs-induced IBs. Consequently, NSs inhibited IFN-α-stimulated tyrosine phosphorylation and nuclear translocation of STAT2. These inhibitory effects as well as the signaling blockade activity were not observed in NSs mutant proteins lacking the STAT2-binding ability. In contrast, NSs affected neither subcellular distribution nor phosphorylation of STAT1 in response to IFN-α and IFN-γ, demonstrating that NSs has little physical and functional interactions with STAT1. Taken together, these results suggest that NSs sequesters STAT2 into NSs-induced IBs, thereby blocking type I IFN JAK-STAT signaling.
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Affiliation(s)
- Yoshinori Kitagawa
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan
| | - Madoka Sakai
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan; Department of Microbiology, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga, 526-0829, Japan
| | - Masayuki Shimojima
- Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Masayuki Saijo
- Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Masae Itoh
- Department of Microbiology, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga, 526-0829, Japan
| | - Bin Gotoh
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan.
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27
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Michalska A, Blaszczyk K, Wesoly J, Bluyssen HAR. A Positive Feedback Amplifier Circuit That Regulates Interferon (IFN)-Stimulated Gene Expression and Controls Type I and Type II IFN Responses. Front Immunol 2018; 9:1135. [PMID: 29892288 PMCID: PMC5985295 DOI: 10.3389/fimmu.2018.01135] [Citation(s) in RCA: 198] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/07/2018] [Indexed: 12/14/2022] Open
Abstract
Interferon (IFN)-I and IFN-II both induce IFN-stimulated gene (ISG) expression through Janus kinase (JAK)-dependent phosphorylation of signal transducer and activator of transcription (STAT) 1 and STAT2. STAT1 homodimers, known as γ-activated factor (GAF), activate transcription in response to all types of IFNs by direct binding to IFN-II activation site (γ-activated sequence)-containing genes. Association of interferon regulatory factor (IRF) 9 with STAT1–STAT2 heterodimers [known as interferon-stimulated gene factor 3 (ISGF3)] or with STAT2 homodimers (STAT2/IRF9) in response to IFN-I, redirects these complexes to a distinct group of target genes harboring the interferon-stimulated response element (ISRE). Similarly, IRF1 regulates expression of ISGs in response to IFN-I and IFN-II by directly binding the ISRE or IRF-responsive element. In addition, evidence is accumulating for an IFN-independent and -dependent role of unphosphorylated STAT1 and STAT2, with or without IRF9, and IRF1 in basal as well as long-term ISG expression. This review provides insight into the existence of an intracellular amplifier circuit regulating ISG expression and controlling long-term cellular responsiveness to IFN-I and IFN-II. The exact timely steps that take place during IFN-activated feedback regulation and the control of ISG transcription and long-term cellular responsiveness to IFN-I and IFN-II is currently not clear. Based on existing literature and our novel data, we predict the existence of a multifaceted intracellular amplifier circuit that depends on unphosphorylated and phosphorylated ISGF3 and GAF complexes and IRF1. In a combinatorial and timely fashion, these complexes mediate prolonged ISG expression and control cellular responsiveness to IFN-I and IFN-II. This proposed intracellular amplifier circuit also provides a molecular explanation for the existing overlap between IFN-I and IFN-II activated ISG expression.
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Affiliation(s)
- Agata Michalska
- Department of Human Molecular Genetics, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Katarzyna Blaszczyk
- Department of Human Molecular Genetics, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Joanna Wesoly
- Laboratory of High Throughput Technologies, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Hans A R Bluyssen
- Department of Human Molecular Genetics, Faculty of Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
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28
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Stark GR, Cheon H, Wang Y. Responses to Cytokines and Interferons that Depend upon JAKs and STATs. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a028555. [PMID: 28620095 DOI: 10.1101/cshperspect.a028555] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Many cytokines and all interferons activate members of a small family of kinases (the Janus kinases [JAKs]) and a slightly larger family of transcription factors (the signal transducers and activators of transcription [STATs]), which are essential components of pathways that induce the expression of specific sets of genes in susceptible cells. JAK-STAT pathways are required for many innate and acquired immune responses, and the activities of these pathways must be finely regulated to avoid major immune dysfunctions. Regulation is achieved through mechanisms that include the activation or induction of potent negative regulatory proteins, posttranslational modification of the STATs, and other modulatory effects that are cell-type specific. Mutations of JAKs and STATs can result in gains or losses of function and can predispose affected individuals to autoimmune disease, susceptibility to a variety of infections, or cancer. Here we review recent developments in the biochemistry, genetics, and biology of JAKs and STATs.
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Affiliation(s)
- George R Stark
- Department of Cancer Biology, Lerner Research Institute of the Cleveland Clinic, Cleveland, Ohio 44195
| | - HyeonJoo Cheon
- Department of Cancer Biology, Lerner Research Institute of the Cleveland Clinic, Cleveland, Ohio 44195
| | - Yuxin Wang
- Department of Cancer Biology, Lerner Research Institute of the Cleveland Clinic, Cleveland, Ohio 44195
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29
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Samuels AL, Louw A, Zareie R, Ingley E. Control of nuclear-cytoplasmic shuttling of Ankrd54 by PKCδ. World J Biol Chem 2017; 8:163-174. [PMID: 28924458 PMCID: PMC5579962 DOI: 10.4331/wjbc.v8.i3.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/28/2017] [Accepted: 05/15/2017] [Indexed: 02/05/2023] Open
Abstract
AIM To identify and characterize the effect of phosphorylation on the subcellular localization of Ankrd54.
METHODS HEK293T cells were treated with calyculin A, staurosporin or phorbol 12-myristate 13-acetate (PMA). Cells were transfected with eGFP-tagged Ankrd54 with or without Lyn tyrosine kinase (wild-type, Y397F mutant, or Y508F mutant). The subcellular localization was assessed by immunofluorescence imaging of cells, immunoblotting of subcellular fractionations. The phosphorylation of Ankrd54 was monitored using Phos-tagTM gel retardation. Phosphorylated peptides were analysed by multiple-reaction-monitoring (MRM) proteomic analysis.
RESULTS Activation of PKC kinases using PMA promoted nuclear export of Ankrd54 and correlated with increased Ankrd54 phosphorylation, assayed using Phos-tagTM gel retardation. Co-expression of an active form of the PKCδ isoform specifically promoted both phosphorylation and cytoplasmic localization of Ankrd54, while PKCδ, Akt and PKA did not. Alanine mutation of several serine residues in the amino-terminal region of Ankrd54 (Ser14, Ser17, Ser18, Ser19) reduced both PMA induced cytoplasmic localization and phosphorylation of Ankrd54. Using MRM proteomic analysis, phosphorylation of the Ser18 residue of Ankrd54 was readily detectable in response to PMA stimulation. PMA stimulation of cells co-expressing Ankrd54 and Lyn tyrosine kinase displayed increased co-immunoprecipitation and enhanced co-localization in the cytoplasm.
CONCLUSION We identify phosphorylation by PKCδ as a major regulator of nuclear-cytoplasmic shuttling of Ankrd54, and its interaction with the tyrosine kinase Lyn.
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Affiliation(s)
- Amy L Samuels
- Cell Signalling Group, Harry Perkins Institute of Medical Research and Centre for Medical Research, the University of Western Australia, Nedlands, WA 6009, Australia
| | - Alison Louw
- Cell Signalling Group, Harry Perkins Institute of Medical Research and Centre for Medical Research, the University of Western Australia, Nedlands, WA 6009, Australia
| | - Reza Zareie
- Proteomics International Laboratories Ltd, Nedlands, WA 6009, Australia
- Proteowa Pty Ltd, SABC, Murdoch University, Murdoch, WA 6150, Australia
| | - Evan Ingley
- Cell Signalling Group, Harry Perkins Institute of Medical Research and Centre for Medical Research, the University of Western Australia, Nedlands, WA 6009, Australia
- Cell Signalling Group, School of Veterinary and Health Sciences, Murdoch University, Murdoch, WA 6150, Australia.
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30
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Goswami R, Kaplan M. STAT Transcription Factors in T Cell Control of Health and Disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2017; 331:123-180. [DOI: 10.1016/bs.ircmb.2016.09.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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31
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Martincuks A, Fahrenkamp D, Haan S, Herrmann A, Küster A, Müller-Newen G. Dissecting functions of the N-terminal domain and GAS-site recognition in STAT3 nuclear trafficking. Cell Signal 2016; 28:810-25. [PMID: 27040695 DOI: 10.1016/j.cellsig.2016.03.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/11/2016] [Accepted: 03/23/2016] [Indexed: 12/25/2022]
Abstract
Signal transducer and activator of transcription 3 (STAT3) is a ubiquitous transcription factor involved in many biological processes, including hematopoiesis, inflammation and cancer progression. Cytokine-induced gene transcription greatly depends on tyrosine phosphorylation of STAT3 on a single tyrosine residue with subsequent nuclear accumulation and specific DNA sequence (GAS) recognition. In this study, we analyzed the roles of the conserved STAT3 N-terminal domain (NTD) and GAS-element binding ability of STAT3 in nucleocytoplasmic trafficking. Our results demonstrate the nonessential role of GAS-element recognition for both cytokine-induced and basal nuclear import of STAT3. Substitution of five key amino acids within the DNA-binding domain rendered STAT3 unable to bind to GAS-elements while still maintaining the ability for nuclear localization. In turn, deletion of the NTD markedly decreased nuclear accumulation upon IL-6 treatment resulting in a prolonged accumulation of phosphorylated dimers in the cytoplasm, at the same time preserving specific DNA recognition ability of the truncation mutant. Observed defect in nuclear localization could not be explained by flawed importin-α binding, since both wild-type and NTD deletion mutant of STAT3 could precipitate both full-length and autoinhibitory domain (∆IBB) deletion mutants of importin-α5, as well as ∆IBB-α3 and ∆IBB-α7 isoforms independently of IL-6 stimulation. Despite its inability to translocate to the nucleus upon IL-6 stimulation, the NTD lacking mutant still showed nuclear accumulation in resting cells similar to wild-type upon inhibition of nuclear export by leptomycin B. At the same time, blocking the nuclear export pathway could not rescue cytoplasmic trapping of phosphorylated STAT3 molecules without NTD. Moreover, STAT3 mutant with dysfunctional SH2 domain (R609Q) also localized in the nucleus of unstimulated cells after nuclear export blocking, while upon cytokine treatment the subcellular localization of this mutant had not changed. Our findings support the concept that basal nucleocytoplasmic shuttling of STAT3 is different from active cytokine-induced nuclear import and does not require conserved N- or SH2-terminal domains, preformed dimer formation and GAS-element-specific DNA recognition.
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Affiliation(s)
- Antons Martincuks
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Dirk Fahrenkamp
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Serge Haan
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany; Molecular Disease Mechanisms Group, Life Sciences Research Unit, University of Luxembourg, 162A Avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg; Signal Transduction Group, Life Sciences Research Unit, University of Luxembourg, 162A Avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg
| | - Andreas Herrmann
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany; Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, USA
| | - Andrea Küster
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Gerhard Müller-Newen
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany.
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Abstract
The oligodendrocyte transcription factor Olig1 is critical for both oligodendrocyte development and remyelination in mice. Nuclear to cytoplasmic translocation of Olig1 protein occurs during brain development and in multiple sclerosis, but the detailed molecular mechanism of this translocation remains elusive. Here, we report that Olig1 acetylation and deacetylation drive its active translocation between the nucleus and the cytoplasm in both mouse and rat oligodendrocytes. We identified three functional nuclear export sequences (NES) localized in the basic helix-loop-helix domain and one specific acetylation site at Lys 150 (human Olig1) in NES1. Olig1 acetylation and deacetylation are regulated by the acetyltransferase CREB-binding protein and the histone deacetylases HDAC1, HDAC3, and HDAC10. Acetylation of Olig1 decreased its chromatin association, increased its interaction with inhibitor of DNA binding 2 and facilitated its retention in the cytoplasm of mature oligodendrocytes. These studies establish that acetylation of Olig1 regulates its chromatin dissociation and subsequent translocation to the cytoplasm and is required for its function in oligodendrocyte maturation.
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Quantifying the dynamics of the oligomeric transcription factor STAT3 by pair correlation of molecular brightness. Nat Commun 2016; 7:11047. [PMID: 27009358 PMCID: PMC4820838 DOI: 10.1038/ncomms11047] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 02/16/2016] [Indexed: 12/21/2022] Open
Abstract
Oligomerization of transcription factors controls their translocation into the nucleus and DNA-binding activity. Here we present a fluorescence microscopy analysis termed pCOMB (pair correlation of molecular brightness) that tracks the mobility of different oligomeric species within live cell nuclear architecture. pCOMB amplifies the signal from the brightest species present and filters the dynamics of the extracted oligomeric population based on arrival time between two locations. We use this method to demonstrate a dependence of signal transducer and activator of transcription 3 (STAT3) mobility on oligomeric state. We find that on entering the nucleus STAT3 dimers must first bind DNA to form STAT3 tetramers, which are also DNA-bound but exhibit a different mobility signature. Examining the dimer-to-tetramer transition by a cross-pair correlation analysis (cpCOMB) reveals that chromatin accessibility modulates STAT3 tetramer formation. Thus, the pCOMB approach is suitable for mapping the impact oligomerization on transcription factor dynamics.
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Camicia R, Winkler HC, Hassa PO. Novel drug targets for personalized precision medicine in relapsed/refractory diffuse large B-cell lymphoma: a comprehensive review. Mol Cancer 2015; 14:207. [PMID: 26654227 PMCID: PMC4676894 DOI: 10.1186/s12943-015-0474-2] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 08/26/2015] [Indexed: 02/07/2023] Open
Abstract
Diffuse large B-cell lymphoma (DLBCL) is a clinically heterogeneous lymphoid malignancy and the most common subtype of non-Hodgkin's lymphoma in adults, with one of the highest mortality rates in most developed areas of the world. More than half of DLBLC patients can be cured with standard R-CHOP regimens, however approximately 30 to 40 % of patients will develop relapsed/refractory disease that remains a major cause of morbidity and mortality due to the limited therapeutic options.Recent advances in gene expression profiling have led to the identification of at least three distinct molecular subtypes of DLBCL: a germinal center B cell-like subtype, an activated B cell-like subtype, and a primary mediastinal B-cell lymphoma subtype. Moreover, recent findings have not only increased our understanding of the molecular basis of chemotherapy resistance but have also helped identify molecular subsets of DLBCL and rational targets for drug interventions that may allow for subtype/subset-specific molecularly targeted precision medicine and personalized combinations to both prevent and treat relapsed/refractory DLBCL. Novel agents such as lenalidomide, ibrutinib, bortezomib, CC-122, epratuzumab or pidilizumab used as single-agent or in combination with (rituximab-based) chemotherapy have already demonstrated promising activity in patients with relapsed/refractory DLBCL. Several novel potential drug targets have been recently identified such as the BET bromodomain protein (BRD)-4, phosphoribosyl-pyrophosphate synthetase (PRPS)-2, macrodomain-containing mono-ADP-ribosyltransferase (ARTD)-9 (also known as PARP9), deltex-3-like E3 ubiquitin ligase (DTX3L) (also known as BBAP), NF-kappaB inducing kinase (NIK) and transforming growth factor beta receptor (TGFβR).This review highlights the new insights into the molecular basis of relapsed/refractory DLBCL and summarizes the most promising drug targets and experimental treatments for relapsed/refractory DLBCL, including the use of novel agents such as lenalidomide, ibrutinib, bortezomib, pidilizumab, epratuzumab, brentuximab-vedotin or CAR T cells, dual inhibitors, as well as mechanism-based combinatorial experimental therapies. We also provide a comprehensive and updated list of current drugs, drug targets and preclinical and clinical experimental studies in DLBCL. A special focus is given on STAT1, ARTD9, DTX3L and ARTD8 (also known as PARP14) as novel potential drug targets in distinct molecular subsets of DLBCL.
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Affiliation(s)
- Rosalba Camicia
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Stem Cell Research Laboratory, NHS Blood and Transplant, Nuffield Division of Clinical, Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.,MRC-UCL Laboratory for Molecular Cell Biology Unit, University College London, Gower Street, London, WC1E6BT, UK
| | - Hans C Winkler
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Institute of Pharmacology and Toxicology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057, Zurich, Switzerland
| | - Paul O Hassa
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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36
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Misasi J, Sullivan NJ. Camouflage and misdirection: the full-on assault of ebola virus disease. Cell 2014; 159:477-86. [PMID: 25417101 DOI: 10.1016/j.cell.2014.10.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Indexed: 01/30/2023]
Abstract
Ebolaviruses cause a severe hemorrhagic fever syndrome that is rapidly fatal to humans and nonhuman primates. Ebola protein interactions with host cellular proteins disrupt type I and type II interferon responses, RNAi antiviral responses, antigen presentation, T-cell-dependent B cell responses, humoral antibodies, and cell-mediated immunity. This multifaceted approach to evasion and suppression of innate and adaptive immune responses in their target hosts leads to the severe immune dysregulation and "cytokine storm" that is characteristic of fatal ebolavirus infection. Here, we highlight some of the processes by which Ebola interacts with its mammalian hosts to evade antiviral defenses.
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Affiliation(s)
- John Misasi
- Boston Children's Hospital, Department of Medicine, Division of Infectious Diseases, Boston, MA 02115, USA
| | - Nancy J Sullivan
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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37
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Bachmann SB, Frommel SC, Camicia R, Winkler HC, Santoro R, Hassa PO. DTX3L and ARTD9 inhibit IRF1 expression and mediate in cooperation with ARTD8 survival and proliferation of metastatic prostate cancer cells. Mol Cancer 2014; 13:125. [PMID: 24886089 PMCID: PMC4070648 DOI: 10.1186/1476-4598-13-125] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 05/07/2014] [Indexed: 12/31/2022] Open
Abstract
Background Prostate cancer (PCa) is one of the leading causes of cancer-related mortality and morbidity in the aging male population and represents the most frequently diagnosed malignancy in men around the world. The Deltex (DTX)-3-like E3 ubiquitin ligase (DTX3L), also known as B-lymphoma and BAL-associated protein (BBAP), was originally identified as a binding partner of the diphtheria-toxin-like macrodomain containing ADP-ribosyltransferase-9 (ARTD9), also known as BAL1 and PARP9. We have previously demonstrated that ARTD9 acts as a novel oncogenic survival factor in high-risk, chemo-resistant, diffuse large B cell lymphoma (DLBCL). The mono-ADP-ribosyltransferase ARTD8, also known as PARP14 functions as a STAT6-specific co-regulator of IL4-mediated proliferation and survival in B cells. Methods Co-expression of DTX3L, ARTD8, ARTD9 and STAT1 was analyzed in the metastatic PCa (mPCa) cell lines PC3, DU145, LNCaP and in the normal prostate luminal epithelial cell lines HPE and RWPE1. Effects on cell proliferation, survival and cell migration were determined in PC3, DU145 and/or LNCaP cells depleted of DTX3L, ARTD8, ARTD9, STAT1 and/or IRF1 compared to their proficient control cells, respectively. In further experiments, real-time RT-PCR, Western blot, immunofluorescence and co-immunoprecipitations were conducted to evaluate the physical and functional interactions between DTX3L, ARTD8 and ARTD9. Results Here we could identify DTX3L, ARTD9 and ARTD8 as novel oncogenic survival factors in mPCa cells. Our studies revealed that DTX3L forms a complex with ARTD8 and mediates together with ARTD8 and ARTD9 proliferation, chemo-resistance and survival of mPCa cells. In addition, DTX3L, ARTD8 and ARTD9 form complexes with each other. Our study provides first evidence that the enzymatic activity of ARTD8 is required for survival of mPCa cells. DTX3L and ARTD9 act together as repressors of the tumor suppressor IRF1 in mPCa cells. Furthermore, the present study shows that DTX3L together with STAT1 and STAT3 is implicated in cell migration of mPCa cells. Conclusions Our data strongly indicate that a crosstalk between STAT1, DTX3L and ARTD-like mono-ADP-ribosyltransferases mediates proliferation and survival of mPCa cells. The present study further suggests that the combined targeted inhibition of STAT1, ARTD8, ARTD9 and/or DTX3L could increase the efficacy of chemotherapy or radiation treatment in prostate and other high-risk tumor types with an increased STAT1 signaling.
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Affiliation(s)
| | | | | | | | | | - Paul O Hassa
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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Ginter T, Fahrer J, Kröhnert U, Fetz V, Garrone A, Stauber RH, Reichardt W, Müller-Newen G, Kosan C, Heinzel T, Krämer OH. Arginine residues within the DNA binding domain of STAT3 promote intracellular shuttling and phosphorylation of STAT3. Cell Signal 2014; 26:1698-706. [PMID: 24721162 DOI: 10.1016/j.cellsig.2014.03.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/20/2014] [Accepted: 03/31/2014] [Indexed: 01/10/2023]
Abstract
Acetylation-dependent inactivation of STAT1 can be mimicked by the exchange of its lysine residues K410 and K413 to glutamine residues. STAT3 harbors non-acetylatable arginine moieties at the corresponding sites R414 and R417. It is unclear whether the mutation of these sites to glutamine residues antagonizes STAT3 activation. Here, we show that an arginine-glutamine-exchange at the STAT3 moieties R414 and R417 (R414Q and R417Q) reduces cytokine-dependent tyrosine phosphorylation of STAT3. This inhibitory effect can be partially rescued by phosphatase inhibition. In addition, the R414Q and R417Q mutations enhance the nuclear accumulation of unphosphorylated STAT3. STAT3 R414Q and STAT3 R417Q show a reduced response to cytokine stimulation emanating from the plasma membrane. Moreover, these STAT3 mutants have no direct inhibitory effect on the cytokine-induced activation of STAT1/STAT3-mediated gene expression. Since the mutations R414Q and R417Q reside within the STAT3 DNA binding domain (DBD), the STAT3 R414Q and R417Q mutants also lack intrinsic activity as transcription factors. Furthermore, in contrast to wild-type STAT3 they cannot compensate for a loss of STAT1 and they cannot promote STAT1/STAT3-dependent transcriptional activation. We further analyzed a STAT3 arginine-lysine-exchange mutant (R414K/R417K). This molecule mimics corresponding lysine residues found within the DBD of STAT1. Compared to wild-type STAT3, the STAT3 R414K/R417K mutant shows attenuated tyrosine phosphorylation and it is a less active transcription factor. In addition, STAT3 R414K/R417K is not activated by deacetylase inhibition. On the other hand, C-terminal acetylation of STAT3 is intact in STAT3 R414K/R417K. Our results suggest that the exchange of amino acid residues within the DBDs of STAT1/STAT3 affects their phosphorylation as well as their intracellular shuttling.
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Affiliation(s)
- Torsten Ginter
- Center for Molecular Biomedicine (CMB), Dept. of Biochemistry, University of Jena, Germany
| | - Jörg Fahrer
- Department of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, 55131 Mainz, Germany
| | - Ulrike Kröhnert
- Center for Molecular Biomedicine (CMB), Dept. of Biochemistry, University of Jena, Germany
| | - Verena Fetz
- Department of Molecular and Cellular Oncology, University Hospital, Mainz, Germany
| | - Alessio Garrone
- Center for Molecular Biomedicine (CMB), Dept. of Biochemistry, University of Jena, Germany
| | - Roland H Stauber
- Department of Molecular and Cellular Oncology, University Hospital, Mainz, Germany
| | - Werner Reichardt
- University of Applied Sciences Jena, Department of Medical Engineering and Biotechnology, 07745 Jena, Germany
| | - Gerhard Müller-Newen
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, 52074 Aachen, Germany
| | - Christian Kosan
- Center for Molecular Biomedicine (CMB), Dept. of Biochemistry, University of Jena, Germany
| | - Thorsten Heinzel
- Center for Molecular Biomedicine (CMB), Dept. of Biochemistry, University of Jena, Germany
| | - Oliver H Krämer
- Department of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, 55131 Mainz, Germany.
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Zaza G, Rascio F, Pontrelli P, Granata S, Stifanelli P, Accetturo M, Ancona N, Gesualdo L, Lupo A, Grandaliano G. Karyopherins: potential biological elements involved in the delayed graft function in renal transplant recipients. BMC Med Genomics 2014; 7:14. [PMID: 24625024 PMCID: PMC3975142 DOI: 10.1186/1755-8794-7-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 03/03/2014] [Indexed: 12/11/2022] Open
Abstract
Background Immediately after renal transplantation, patients experience rapid and significant improvement of their clinical conditions and undergo considerable systemic and cellular modifications. However, some patients present a slow recovery of the renal function commonly defined as delayed graft function (DGF). Although clinically well characterized, the molecular mechanisms underlying this condition are not totally defined, thus, we are currently missing specific clinical markers to predict and to make early diagnosis of this event. Methods We investigated, using a pathway analysis approach, the transcriptomic profile of peripheral blood mononuclear cells (PBMC) from renal transplant recipients with DGF and with early graft function (EGF), before (T0) and 24 hours (T24) after transplantation. Results Bioinformatics/statistical analysis showed that 15 pathways (8 up-regulated and 7 down-regulated) and 11 pathways (5 up-regulated and 6 down-regulated) were able to identify DGF patients at T0 and T24, respectively. Interestingly, the most up-regulated pathway at both time points was NLS-bearing substrate import into nucleus, which includes genes encoding for several subtypes of karyopherins, a group of proteins involved in nucleocytoplasmic transport. Signal transducers and activators of transcription (STAT) utilize karyopherins-alpha (KPNA) for their passage from cytoplasm into the nucleus. In vitro functional analysis demonstrated that in PBMCs of DGF patients, there was a significant KPNA-mediated nuclear translocation of the phosphorylated form of STAT3 (pSTAT3) after short-time stimulation (2 and 5 minutes) with interleukin-6. Conclusions Our study suggests the involvement, immediately before transplantation, of karyopherin-mediated nuclear transport in the onset and development of DGF. Additionally, it reveals that karyopherins could be good candidates as potential DGF predictive clinical biomarkers and targets for pharmacological interventions in renal transplantation. However, because of the low number of patients analyzed and some methodological limitations, additional studies are needed to validate and to better address these points.
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Affiliation(s)
- Gianluigi Zaza
- Renal Unit, Department of Medicine, University-Hospital of Verona, Piazzale A, Stefani 1, 37126 Verona (VR), Italy.
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Renjini AP, Titus S, Narayan P, Murali M, Jha RK, Laloraya M. STAT3 and MCL-1 associate to cause a mesenchymal epithelial transition. J Cell Sci 2014; 127:1738-50. [PMID: 24481815 DOI: 10.1242/jcs.138214] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Embryo implantation is effected by a myriad of signaling cascades acting on the embryo-endometrium axis. Here we show, by using MALDI TOF analysis, far-western analysis and colocalization and co-transfection studies, that STAT3 and MCL-1 are interacting partners during embryo implantation. We show in vitro that the interaction between the two endogenous proteins is strongly regulated by estrogen and progesterone. Implantation, pregnancy and embryogenesis are distinct from any other process in the body, with extensive, but controlled, proliferation, cell migration, apoptosis, cell invasion and differentiation. Cellular plasticity is vital during the early stages of development for morphogenesis and organ homeostasis, effecting the epithelial to mesenchymal transition (EMT) and, the reverse process, mesenchymal to epithelial transition (MET). STAT3 functionally associates with MCL-1 in the mammalian breast cancer cell line MCF7 that overexpresses STAT3 and MCL-1, which leads to an increased rate of apoptosis and decreased cellular invasion, disrupting the EMT. Association of MCL-1 with STAT3 modulates the normal, anti-apoptotic, activity of MCL-1, resulting in pro-apoptotic effects. Studying the impact of the association of STAT3 with MCL-1 on MET could lead to an enhanced understanding of pregnancy and infertility, and also metastatic tumors.
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Affiliation(s)
- A P Renjini
- Utero-Embryo Repromics Lab, Division of Molecular Reproduction, Rajiv Gandhi Centre for Biotechnology, Thycaud PO, Poojappura, Thiruvananthapuram 695 014, Kerala, India
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Tunable signal processing through a kinase control cycle: the IKK signaling node. Biophys J 2014; 105:231-41. [PMID: 23823243 DOI: 10.1016/j.bpj.2013.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 04/19/2013] [Accepted: 05/02/2013] [Indexed: 12/31/2022] Open
Abstract
The transcription factor NFκB, a key component of the immune system, shows intricate stimulus-specific temporal dynamics. Those dynamics are thought to play a role in controlling the physiological response to cytokines and pathogens. Biochemical evidence suggests that the NFκB inducing kinase, IKK, a signaling hub onto which many signaling pathways converge, is regulated via a regulatory cycle comprising a poised, an active, and an inactive state. We hypothesize that it operates as a modulator of signal dynamics, actively reshaping the signals generated at the receptor proximal level. Here we show that a regulatory cycle can function in at least three dynamical regimes, tunable by regulating a single kinetic parameter. In particular, the simplest three-state regulatory cycle can generate signals with two well-defined phases, each with distinct coding capabilities in terms of the information they can carry about the stimulus. We also demonstrate that such a kinase cycle can function as a signal categorizer classifying diverse incoming signals into outputs with a limited set of temporal activity profiles. Finally, we discuss the extension of the results to other regulatory motifs that could be understood in terms of the regimes of the three-state cycle.
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42
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Steen HC, Gamero AM. STAT2 phosphorylation and signaling. JAKSTAT 2013; 2:e25790. [PMID: 24416652 PMCID: PMC3876438 DOI: 10.4161/jkst.25790] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 12/31/2022] Open
Abstract
STAT2 is an essential transcription factor in type I IFN mediated anti-viral and anti-proliferative signaling. STAT2 function is regulated by tyrosine phosphorylation, which is the trigger for STAT-dimerization, subsequent nuclear translocation, and transcriptional activation of IFN stimulated genes. Evidence of additional STAT2 phosphorylation sites has emerged as well as novel roles for STAT2 separate from the classical ISGF3-signaling. This review aims to summarize knowledge of phosphorylation-mediated STAT2-regulation and future avenues of related STAT2 research.
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Affiliation(s)
- Håkan C Steen
- Department of Biochemistry; Temple University School of Medicine; Philadelphia, PA USA
| | - Ana M Gamero
- Department of Biochemistry; Temple University School of Medicine; Philadelphia, PA USA
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Cell geometric constraints induce modular gene-expression patterns via redistribution of HDAC3 regulated by actomyosin contractility. Proc Natl Acad Sci U S A 2013; 110:11349-54. [PMID: 23798429 DOI: 10.1073/pnas.1300801110] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Physical forces in the form of substrate rigidity or geometrical constraints have been shown to alter gene expression profile and differentiation programs. However, the underlying mechanism of gene regulation by these mechanical cues is largely unknown. In this work, we use micropatterned substrates to alter cellular geometry (shape, aspect ratio, and size) and study the nuclear mechanotransduction to regulate gene expression. Genome-wide transcriptome analysis revealed cell geometry-dependent alterations in actin-related gene expression. Increase in cell size reinforced expression of matrix-related genes, whereas reduced cell-substrate contact resulted in up-regulation of genes involved in cellular homeostasis. We also show that large-scale changes in gene-expression profile mapped onto differential modulation of nuclear morphology, actomyosin contractility and histone acetylation. Interestingly, cytoplasmic-to-nuclear redistribution of histone deacetylase 3 modulated histone acetylation in an actomyosin-dependent manner. In addition, we show that geometric constraints altered the nuclear fraction of myocardin-related transcription factor. These fractions exhibited hindered diffusion time scale within the nucleus, correlated with enhanced serum-response element promoter activity. Furthermore, nuclear accumulation of myocardin-related transcription factor also modulated NF-κB activity. Taken together, our work provides modularity in switching gene-expression patterns by cell geometric constraints via actomyosin contractility.
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Shin HY, Reich NC. Dynamic trafficking of STAT5 depends on an unconventional nuclear localization signal. J Cell Sci 2013; 126:3333-43. [PMID: 23704351 DOI: 10.1242/jcs.123042] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Signal transducer and activator of transcription 5 (STAT5) is crucial for physiological processes that include hematopoiesis, liver metabolism and mammary gland development. However, aberrant continual activity of STAT5 has been causally linked to human leukemias and solid tumor formation. As a regulated transcription factor, precise cellular localization of STAT5 is essential. Conventional nuclear localization signals consist of short stretches of basic amino acids. In this study, we provide evidence that STAT5 nuclear import is dependent on an unconventional nuclear localization signal that functions within the conformation of an extensive coiled-coil domain. Both in vitro binding and in vivo functional assays reveal that STAT5 nuclear import is mediated by the importin-α3/β1 system independently of STAT5 activation by tyrosine phosphorylation. The integrity of the coiled-coil domain is essential for STAT5 transcriptional induction of the β-casein gene following prolactin stimulation as well as its ability to synergize with the glucocorticoid receptor. The glucocorticoid receptor accumulates in the nucleus in response to prolactin and this nuclear import is dependent on STAT5 nuclear import. STAT5 continually shuttles in and out of the nucleus and live cell imaging demonstrates that STAT5 nuclear export is mediated by both chromosome region maintenance 1 (Crm1)-dependent and Crm1-independent pathways. A Crm1-dependent nuclear export signal was identified within the STAT5 N-terminus. These findings provide insight into the fundamental mechanisms that regulate STAT5 nuclear trafficking and cooperation with the glucocorticoid receptor and provide a basis for clinical intervention of STAT5 function in disease.
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Affiliation(s)
- Ha Youn Shin
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794, USA
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Audzevich T, Pearce G, Breucha M, Günal G, Jessberger R. Control of the STAT6-BCL6 antagonism by SWAP-70 determines IgE production. THE JOURNAL OF IMMUNOLOGY 2013; 190:4946-55. [PMID: 23589612 DOI: 10.4049/jimmunol.1203014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Asthma and allergies are major health concerns in which Ig isotype E plays a pivotal role. Ag-bound IgE drives mast cells and basophils into exocytosis, thereby promoting allergic and potentially anaphylactic reactions. The importance of tightly regulated IgE production is underscored by severe immunological conditions in humans with elevated IgE levels. Cytokines direct IgH class-switching to a particular isotype by initiation of germline transcription (GLT) from isotype-specific intronic (I) promoters. The switch to IgE depends on IL-4, which stimulates GLT of the Iε promoter, but is specifically and strongly impaired in Swap-70(-/-) mice. Although early events in IL-4 signal transduction (i.e., activation of the JAK/STAT6 pathway) do not require SWAP-70, SWAP-70 deficiency results in impaired Iε GLT. The affinity of STAT6 to chromatin is reduced in absence of SWAP-70. Chromatin immunoprecipitation revealed that SWAP-70 binds to Iε and is required for association of STAT6 with Iε. BCL6, known to antagonize STAT6 particularly at Iε, is increased on Iε in absence of SWAP-70. Other promoters bound by BCL6 and STAT6 were found unaffected. We conclude that SWAP-70 controls IgE production through regulation of the antagonistic STAT6 and BCL6 occupancy of Iε. The identification of this mechanism opens new avenues to inhibit allergic reactions triggered by IgE.
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Affiliation(s)
- Tatsiana Audzevich
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Dresden University of Technology, 01307 Dresden, Germany
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Geisbrecht ER, Sawant K, Su Y, Liu ZC, Silver DL, Burtscher A, Wang X, Zhu AJ, McDonald JA. Genetic interaction screens identify a role for hedgehog signaling in Drosophila border cell migration. Dev Dyn 2013; 242:414-31. [PMID: 23335293 DOI: 10.1002/dvdy.23926] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 12/22/2012] [Accepted: 12/28/2012] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Cell motility is essential for embryonic development and physiological processes such as the immune response, but also contributes to pathological conditions such as tumor progression and inflammation. However, our understanding of the mechanisms underlying migratory processes is incomplete. Drosophila border cells provide a powerful genetic model to identify the roles of genes that contribute to cell migration. RESULTS Members of the Hedgehog signaling pathway were uncovered in two independent screens for interactions with the small GTPase Rac and the polarity protein Par-1 in border cell migration. Consistent with a role in migration, multiple Hh signaling components were enriched in the migratory border cells. Interference with Hh signaling by several different methods resulted in incomplete cell migration. Moreover, the polarized distribution of E-Cadherin and a marker of tyrosine kinase activity were altered when Hh signaling was disrupted. Conservation of Hh-Rac and Hh-Par-1 signaling was illustrated in the wing, in which Hh-dependent phenotypes were enhanced by loss of Rac or par-1. CONCLUSIONS We identified a pathway by which Hh signaling connects to Rac and Par-1 in cell migration. These results further highlight the importance of modifier screens in the identification of new genes that function in developmental pathways.
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Affiliation(s)
- Erika R Geisbrecht
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA
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Cimica V, Reich NC. Nuclear trafficking of STAT proteins visualized by live cell imaging. Methods Mol Biol 2013; 967:189-202. [PMID: 23296731 DOI: 10.1007/978-1-62703-242-1_14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The ability to observe the dynamic localization of a protein in living cells can provide critical insight to its mode of action and functional molecular interactions. To this purpose, green fluorescent protein (GFP) has served as a powerful tool to tag STAT proteins for microscopic visualization. Live cell imaging with STAT-GFP proteins has contributed to our understanding of signal transduction and the complexities of nuclear transport of STAT proteins. In this report we summarize recent approaches that use GFP-based techniques with live cell imaging to study the mechanisms of STAT nuclear import and export: photoactivation, fluorescence recovery after photobleaching (FRAP), and fluorescence loss in photobleaching (FLIP).
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Affiliation(s)
- Velasco Cimica
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
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Tsai TL, Hou CC, Wang HC, Yang ZS, Yeh CS, Shieh DB, Su WC. Nucleocytoplasmic transport blockage by SV40 peptide-modified gold nanoparticles induces cellular autophagy. Int J Nanomedicine 2012; 7:5215-34. [PMID: 23071392 PMCID: PMC3469097 DOI: 10.2147/ijn.s35125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Gold nanoparticles modified with the nuclear localization signal from simian virus 40 large T antigen (GNP-PEG/SV40) accumulate on the cytoplasmic side of the nuclear membrane in HeLa cells. Accumulation of GNP-PEG/SV40 around the nucleus blocks nucleocytoplasmic transport and prevents RNA export and nuclear shuttling of signaling proteins. This long-term blockage of nucleocytoplasmic transport results in cell death. This cell death is not caused by apoptosis or necrosis because caspases 3 and 9 are not activated, and the expression of annexin V/propidium iodide is not enhanced in HeLa cells after treatment. Using transmission electron microscopy, autophagosomes and autolysosomes were seen to appear after 72 hours of treatment with GNP-PEG/SV40. Increasing levels of enhanced green fluorescent protein-microtubule-associated protein 1 light chain 3 (EGFP-LC3)-positive punctate and LC3-II confirmed GNP-PEG/SV40-induced autophagy. In SiHa cells, treatment did not induce accumulation of GNP-PEG/SV40 around the nucleus and autophagy. Treating cells with wheat germ agglutinin, a nuclear pore complex inhibitor, induced autophagy in both HeLa and SiHa cells. GNP-PEG/SV40-induced autophagy plays a role in cell death, not survival, and virus-mediated small hairpin RNA silencing of Beclin-1 attenuates cell death. Taken together, the results indicate that long-term blockade of nucleocytoplasmic transport results in autophagic cell death.
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Affiliation(s)
- Tsung-Lin Tsai
- Institute of Basic Medical Sciences, National Cheng Kung University, and Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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Zhang APP, Abelson DM, Bornholdt ZA, Liu T, Woods VL, Saphire EO. The ebolavirus VP24 interferon antagonist: know your enemy. Virulence 2012; 3:440-5. [PMID: 23076242 DOI: 10.4161/viru.21302] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Suppression during the early phases of the immune system often correlates directly with a fatal outcome for the host. The ebolaviruses, some of the most lethal viruses known, appear to cripple initial stages of the host defense network via multiple distinct paths. Two of the eight viral proteins are critical for immunosuppression. One of these proteins is VP35, which binds double-stranded RNA and antagonizes several antiviral signaling pathways. The other protein is VP24, which binds transporter molecules to prevent STAT1 translocation. A more recent discovery is that VP24 also binds STAT1 directly, suggesting that VP24 may operate in at least two separate branches of the interferon pathway. New crystal structures of VP24 derived from pathogenic and nonpathogenic ebolaviruses reveal its novel, pyramidal fold, upon which can be mapped sites required for virulence and for STAT1 binding. These structures of VP24, and new information about its direct binding to STAT1, provide avenues by which we may explore its many roles in the viral life cycle, and reasons for differences in pathogenesis among the ebolaviruses.
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Affiliation(s)
- Adrianna P P Zhang
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, USA
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Oh HM, Yu CR, Dambuza I, Marrero B, Egwuagu CE. STAT3 protein interacts with Class O Forkhead transcription factors in the cytoplasm and regulates nuclear/cytoplasmic localization of FoxO1 and FoxO3a proteins in CD4(+) T cells. J Biol Chem 2012; 287:30436-43. [PMID: 22761423 DOI: 10.1074/jbc.m112.359661] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
An important feature of the adaptive immune response is its remarkable capacity to regulate the duration of inflammatory responses, and effector T cells have been shown to limit excessive immune responses by producing anti-inflammatory cytokines such as IL-10 and IL-27. However, how anti-inflammatory cytokines mediate their suppressive activities is not well understood. In this study, we show that STAT3 contributes to mechanisms that control the duration of T cell proliferation by regulating the subcellular location of FoxO1 and FoxO3a, two Class O Forkhead transcription factors that mediate lymphocyte quiescence and inhibit T cell activation. We show that active FoxO1 and FoxO3a reside exclusively in the nucleus of naïve T cells whereas inactive pFoxO1 and pFoxO3a were most abundant in activated T cells and sequestered in their cytoplasm in association with unphosphorylated STAT3 (U-STAT3) and 14-3-3. We further show that FoxO1/FoxO3a rapidly relocalized into the nucleus in response to pSTAT3 activation by IL-6 or IL-10, and the accumulation of FoxO1/FoxO3a in their nuclei coincided with increased expression of p27(Kip1) and p21(WAF1). STAT3 inhibitors completely abrogated cytokine-induced translocation of FoxO1/FoxO3a into the nucleus. In naïve or resting STAT3-deficient T cells, expression of pFoxO1/pFoxO3a was predominantly in the cytoplasm and correlated with defects in p27(Kip1) and p21(WAF1) expression, suggesting requirement of STAT3 for importation or retention of FoxO in the nucleus and attenuation of lymphocyte proliferation. Taken together, these results suggest that U-STAT3 collaborates with 14-3-3 to sequester pFoxO1/pFoxO3a in cytoplasm and thus prolong T cell activation, whereas pSTAT3 activation by anti-inflammatory cytokines would curtail the duration of TCR activation and re-establish lymphocyte quiescence by inducing nuclear localization of FoxO1/FoxO3a and FoxO-mediated expression of growth-inhibitory proteins.
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Affiliation(s)
- Hyun-Mee Oh
- Molecular Immunology Section, NEI, National Institutes of Health, Bethesda, MD 20892, USA
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