1
|
Fan S, Popli S, Chakravarty S, Chakravarti R, Chattopadhyay S. Non-transcriptional IRF7 interacts with NF-κB to inhibit viral inflammation. J Biol Chem 2024; 300:107200. [PMID: 38508315 PMCID: PMC11040127 DOI: 10.1016/j.jbc.2024.107200] [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: 08/28/2023] [Revised: 02/23/2024] [Accepted: 03/10/2024] [Indexed: 03/22/2024] Open
Abstract
Interferon (IFN) regulatory factors (IRF) are key transcription factors in cellular antiviral responses. IRF7, a virus-inducible IRF, expressed primarily in myeloid cells, is required for transcriptional induction of interferon α and antiviral genes. IRF7 is activated by virus-induced phosphorylation in the cytoplasm, leading to its translocation to the nucleus for transcriptional activity. Here, we revealed a nontranscriptional activity of IRF7 contributing to its antiviral functions. IRF7 interacted with the pro-inflammatory transcription factor NF-κB-p65 and inhibited the induction of inflammatory target genes. Using knockdown, knockout, and overexpression strategies, we demonstrated that IRF7 inhibited NF-κB-dependent inflammatory target genes, induced by virus infection or toll-like receptor stimulation. A mutant IRF7, defective in transcriptional activity, interacted with NF-κB-p65 and suppressed NF-κB-induced gene expression. A single-action IRF7 mutant, active in anti-inflammatory function, but defective in transcriptional activity, efficiently suppressed Sendai virus and murine hepatitis virus replication. We, therefore, uncovered an anti-inflammatory function for IRF7, independent of transcriptional activity, contributing to the antiviral response of IRF7.
Collapse
Affiliation(s)
- Shumin Fan
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Science, Toledo, Ohio, USA
| | - Sonam Popli
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Science, Toledo, Ohio, USA
| | - Sukanya Chakravarty
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Science, Toledo, Ohio, USA; Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Ritu Chakravarti
- Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Science, Toledo, Ohio, USA
| | - Saurabh Chattopadhyay
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Science, Toledo, Ohio, USA; Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA.
| |
Collapse
|
2
|
Chakravarty S, Chakravarti R, Chattopadhyay S. Inflammatory Control of Viral Infection. Viruses 2023; 15:1579. [PMID: 37515265 PMCID: PMC10383133 DOI: 10.3390/v15071579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023] Open
Abstract
Inflammatory responses during virus infection differentially impact the host. Managing inflammatory responses is essential in controlling viral infection and related diseases. Recently, we identified a cellular anti-inflammatory mechanism, RIKA (Repression of IRF3-mediated inhibition of NF-κB activity), which controls viral inflammation and pathogenesis. The RIKA function of IRF3 may be explored further in other inflammatory diseases beyond viral infection.
Collapse
Affiliation(s)
- Sukanya Chakravarty
- Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| | - Ritu Chakravarti
- Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| | - Saurabh Chattopadhyay
- Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| |
Collapse
|
3
|
The Role of STING in Liver Injury Is Both Stimulus- and Time-Dependent. Nutrients 2022; 14:nu14194029. [PMID: 36235681 PMCID: PMC9572800 DOI: 10.3390/nu14194029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 09/26/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
STING, Tmem173, is involved in liver injury caused by both infectious and sterile inflammatory models. Its role in toxic liver injury and non-alcoholic fatty liver disease (NAFLD), however, is less clear. While a few groups have investigated its role in NAFLD pathogenesis, results have been conflicting. The objective of this study was to clarify the exact role of STING in toxic liver injury and NAFLD models. Goldenticket mice (Tmem173gt), which lack STING protein, were subjected to either a toxic liver injury with tunicamycin (TM) or one of two dietary models of non-alcoholic fatty liver disease: high fructose feeding or Fructose-Palmitate-Cholesterol (FPC) feeding. Three days after TM injection, Tmem173gt mice demonstrated less liver injury (average ALT of 54 ± 5 IU/L) than control mice (average ALT 108 ± 24 IU/L). In contrast, no significant differences in liver injury were seen between WT and Tmem173gt mice fed either high fructose or FPC. Tmem173gt mice only distinguished themselves from WT mice in their increased insulin resistance. In conclusion, while STING appears to play a role in toxic liver injury mediated by TM, it plays little to no role in two dietary models of NAFLD. The exact role of STING appears to be stimulus-dependent.
Collapse
|
4
|
IRF3 inhibits nuclear translocation of NF-κB to prevent viral inflammation. Proc Natl Acad Sci U S A 2022; 119:e2121385119. [PMID: 36067309 PMCID: PMC9478676 DOI: 10.1073/pnas.2121385119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interferon (IFN) regulatory factor 3 (IRF3) is a transcription factor activated by phosphorylation in the cytoplasm of a virus-infected cell; by translocating to the nucleus, it induces transcription of IFN-β and other antiviral genes. We have previously reported IRF3 can also be activated, as a proapoptotic factor, by its linear polyubiquitination mediated by the RIG-I pathway. Both transcriptional and apoptotic functions of IRF3 contribute to its antiviral effect. Here, we report a nontranscriptional function of IRF3, namely, the repression of IRF3-mediated NF-κB activity (RIKA), which attenuated viral activation of NF-κB and the resultant inflammatory gene induction. In Irf3-/- mice, consequently, Sendai virus infection caused enhanced inflammation in the lungs. Mechanistically, RIKA was mediated by the direct binding of IRF3 to the p65 subunit of NF-κB in the cytoplasm, which prevented its nuclear import. A mutant IRF3 defective in both the transcriptional and the apoptotic activities was active in RIKA and inhibited virus replication. Our results demonstrated IRF3 deployed a three-pronged attack on virus replication and the accompanying inflammation.
Collapse
|
5
|
Halimani N, Nesterchuk M, Andreichenko IN, Tsitrina AA, Elchaninov A, Lokhonina A, Fatkhudinov T, Dashenkova NO, Brezgina V, Zatsepin TS, Mikaelyan AS, Kotelevtsev YV. Phenotypic Alteration of BMDM In Vitro Using Small Interfering RNA. Cells 2022; 11:cells11162498. [PMID: 36010574 PMCID: PMC9406732 DOI: 10.3390/cells11162498] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/05/2022] [Accepted: 08/09/2022] [Indexed: 11/03/2022] Open
Abstract
Autologous macrophage transfer is an emerging platform for cell therapy. It is anticipated that conventional macrophage reprogramming based on ex vivo polarization using cytokines and ligands of TLRs may enhance the therapeutic effect. We describe an alternative approach based on small interfering RNA (siRNA) knockdown of selected molecular cues of macrophage polarization, namely EGR2, IRF3, IRF5, and TLR4 in Raw264.7 monocyte/macrophage cell line and mouse-bone-marrow-derived macrophages (BMDMs). The impact of IRF5 knockdown was most pronounced, curtailing the expression of other inflammatory mediators such as IL-6 and NOS2, especially in M1-polarized macrophages. Contrary to IRF5, EGR2 knockdown potentiated M1-associated markers while altogether abolishing M2 marker expression, which is indicative of the principal role of EGR2 in the maintenance of alternative phenotypes. IRF3 knockdown suppressed M1 polarization but upregulated Arg 1, a canonical marker of alternative polarization in M1 macrophages. As anticipated, the knockdown of TLR4 also attenuated the M1 phenotype but, akin to IRF3, significantly induced Arginase 1 in M0 and M1, driving the phenotype towards M2. This study validates RNAi as a viable option for the alteration and maintenance of macrophage phenotypes.
Collapse
Affiliation(s)
- Noreen Halimani
- Vladimir Zelman Center for Neurobiology and Brain Rehabilitation and Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 143025, Russia
- Correspondence: (N.H.); (Y.V.K.)
| | - Mikhail Nesterchuk
- Vladimir Zelman Center for Neurobiology and Brain Rehabilitation and Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 143025, Russia
| | - Irina N. Andreichenko
- Vladimir Zelman Center for Neurobiology and Brain Rehabilitation and Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 143025, Russia
| | - Alexandra A. Tsitrina
- Koltzov Institute of Developmental Biology of Russian Academy of Sciences, 26 Vavilov Street, Moscow 119334, Russia
| | - Andrey Elchaninov
- National Medical Research Center for Obstetrics, Gynecology and Perinatology Named after Academician V.I. Kulakov, Russian Federation, 4 Oparina Street, Moscow 117997, Russia
- Department of Histology, Pirogov Russian National Research Medical University, Ministry of Healthcare of The Russian Federation, 1 Ostrovitianov Street, Moscow 117997, Russia
| | - Anastasia Lokhonina
- National Medical Research Center for Obstetrics, Gynecology and Perinatology Named after Academician V.I. Kulakov, Russian Federation, 4 Oparina Street, Moscow 117997, Russia
- Department of Histology, Cytology and Embryology, Peoples’ Friendship University of Russia, 6 Miklukho-Maklaya Street, Moscow 117198, Russia
| | - Timur Fatkhudinov
- Department of Histology, Pirogov Russian National Research Medical University, Ministry of Healthcare of The Russian Federation, 1 Ostrovitianov Street, Moscow 117997, Russia
- Scientific Research Institute of Human Morphology, 3 Tsurupa Street, Moscow 117418, Russia
| | - Nataliya O. Dashenkova
- Koltzov Institute of Developmental Biology of Russian Academy of Sciences, 26 Vavilov Street, Moscow 119334, Russia
| | - Vera Brezgina
- Vladimir Zelman Center for Neurobiology and Brain Rehabilitation and Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 143025, Russia
| | - Timofei S. Zatsepin
- Vladimir Zelman Center for Neurobiology and Brain Rehabilitation and Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 143025, Russia
| | - Arsen S. Mikaelyan
- Koltzov Institute of Developmental Biology of Russian Academy of Sciences, 26 Vavilov Street, Moscow 119334, Russia
| | - Yuri V. Kotelevtsev
- Vladimir Zelman Center for Neurobiology and Brain Rehabilitation and Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow 143025, Russia
- Correspondence: (N.H.); (Y.V.K.)
| |
Collapse
|
6
|
Patel SJ, Liu N, Piaker S, Gulko A, Andrade ML, Heyward FD, Sermersheim T, Edinger N, Srinivasan H, Emont MP, Westcott GP, Luther J, Chung RT, Yan S, Kumari M, Thomas R, Deleye Y, Tchernof A, White PJ, Baselli GA, Meroni M, De Jesus DF, Ahmad R, Kulkarni RN, Valenti L, Tsai L, Rosen ED. Hepatic IRF3 fuels dysglycemia in obesity through direct regulation of Ppp2r1b. Sci Transl Med 2022; 14:eabh3831. [PMID: 35320000 PMCID: PMC9162056 DOI: 10.1126/scitranslmed.abh3831] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Inflammation has profound but poorly understood effects on metabolism, especially in the context of obesity and nonalcoholic fatty liver disease (NAFLD). Here, we report that hepatic interferon regulatory factor 3 (IRF3) is a direct transcriptional regulator of glucose homeostasis through induction of Ppp2r1b, a component of serine/threonine phosphatase PP2A, and subsequent suppression of glucose production. Global ablation of IRF3 in mice on a high-fat diet protected against both steatosis and dysglycemia, whereas hepatocyte-specific loss of IRF3 affects only dysglycemia. Integration of the IRF3-dependent transcriptome and cistrome in mouse hepatocytes identifies Ppp2r1b as a direct IRF3 target responsible for mediating its metabolic actions on glucose homeostasis. IRF3-mediated induction of Ppp2r1b amplified PP2A activity, with subsequent dephosphorylation of AMPKα and AKT. Furthermore, suppression of hepatic Irf3 expression with antisense oligonucleotides reversed obesity-induced insulin resistance and restored glucose homeostasis in obese mice. Obese humans with NAFLD displayed enhanced activation of liver IRF3, with reversion after bariatric surgery. Hepatic PPP2R1B expression correlated with HgbA1C and was elevated in obese humans with impaired fasting glucose. We therefore identify the hepatic IRF3-PPP2R1B axis as a causal link between obesity-induced inflammation and dysglycemia and suggest an approach for limiting the metabolic dysfunction accompanying obesity-associated NAFLD.
Collapse
Affiliation(s)
- Suraj J. Patel
- Division of Gastroenterology and Hepatology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Division of Gastroenterology, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Boston, MA 02115, USA
- Division of Digestive and Liver Diseases, Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Nan Liu
- Harvard Medical School, Boston, MA 02115, USA
- Cancer and Blood Disorders Center, Dana Farber Cancer Institute and Boston Children’s Hospital, Boston, MA 02215, USA
- Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou 311121, China
| | - Sam Piaker
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Division of Gastroenterology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Anton Gulko
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Maynara L. Andrade
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Frankie D. Heyward
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Tyler Sermersheim
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Nufar Edinger
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Harini Srinivasan
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Margo P. Emont
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Gregory P. Westcott
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Jay Luther
- Division of Gastroenterology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Raymond T. Chung
- Division of Gastroenterology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Shuai Yan
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Manju Kumari
- Department of Cardiology, Internal Medicine III, University of Heidelberg, Heidelberg, Germany
| | - Reeby Thomas
- Immunology and Microbiology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Yann Deleye
- Duke Molecular Physiology Institute and Division of Endocrinology, Metabolism and Nutrition, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - André Tchernof
- Institut Universitaire de Cardiologie and Pneumologie de Québec–Université Laval (IUCPQUL), Québec City, Canada
| | - Phillip J. White
- Duke Molecular Physiology Institute and Division of Endocrinology, Metabolism and Nutrition, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Guido A. Baselli
- Department of Pathophysiology and Transplantation, Universita degli Studi di Milano, Milan, Italy
- Precision Medicine, Department of Transfusion Medicine and Hematology, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Marica Meroni
- General Medicine and Metabolic Diseases, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Dario F. De Jesus
- Harvard Medical School, Boston, MA 02115, USA
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02215, USA
| | - Rasheed Ahmad
- Immunology and Microbiology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Rohit N. Kulkarni
- Harvard Medical School, Boston, MA 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02215, USA
| | - Luca Valenti
- Department of Pathophysiology and Transplantation, Universita degli Studi di Milano, Milan, Italy
- Precision Medicine, Department of Transfusion Medicine and Hematology, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Linus Tsai
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Evan D. Rosen
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| |
Collapse
|
7
|
The antiviral action of the RIG-I induced pathway of apoptosis (RIPA) is enhanced by its ability to degrade Otulin, which deubiquitinates IRF3. Cell Death Differ 2022; 29:504-513. [PMID: 34545182 PMCID: PMC8901756 DOI: 10.1038/s41418-021-00870-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 12/25/2022] Open
Abstract
Mammalian innate immune response to virus infection is meditated by many cell-intrinsic pathways. RNA viruses, such as Sendai virus, which replicate in the cytoplasm, trigger the RIG-I-like receptor pathway, which activates the transcription factor, IRF3. Activated IRF3 translocates to the nucleus and induces transcription of the genes which encode interferons, the major antiviral cytokines. Interestingly, IRF3 activates another interferon-independent antiviral pathway, called RIG-I induced pathway of apoptosis (RIPA). For activating RIPA, IRF3 translocates from the cytoplasm to mitochondria. RIPA requires linear polyubiquitination of IRF3 by the enzyme complex, LUBAC; ubiquitinated IRF3 binds to Bax and translocates it to mitochondria causing the release of Cytochrome C, activation of caspases and apoptosis of the infected cell. Here, we report that Otulin, the deubiquitinase that removes linear polyubiquitin chains, inhibits RIPA by deubiquitinating IRF3. Ablation of Otulin expression enhanced RIPA and its overexpression inhibited RIPA. In virus-infected cells, to overcome Otulin-mediated inhibition, RIPA actively degrades Otulin. This degradation required sequential actions of RIPA-activated Caspase 3 and proteasomes. Caspase 3 cleaved Otulin at D31; the D31A mutant was not cleaved at all. The caspase-cleaved fragment was totally degraded by proteasomes, which was preceded by its K48-linked ubiquitination. Mass spectrometric analysis of Otulin identified K64 and K197 as the ubiquitinated residues. Otulin interacted with LUBAC after virus infection and the E3-ubiquitin ligase, HOIP, a component of LUBAC, ubiquitinated Otulin to trigger its proteasome-mediated degradation. To assess the impact of Otulin degradation on RIPA-mediated antiviral action, we expressed, in Otulin-ablated cells, a non-degradable mutant of Otulin, in which D31, K64 and K197 had been mutated. The cells expressing the Otulin mutant were less susceptible to virus-induced apoptosis, because RIPA was less active, and consequently virus replication was more robust. Thus, our study has revealed an important positive feedback loop of RIPA.
Collapse
|
8
|
Glanz A, Chakravarty S, Fan S, Chawla K, Subramanian G, Rahman T, Walters D, Chakravarti R, Chattopadhyay S. Autophagic degradation of IRF3 induced by the small-molecule auranofin inhibits its transcriptional and proapoptotic activities. J Biol Chem 2021; 297:101274. [PMID: 34619149 PMCID: PMC8531670 DOI: 10.1016/j.jbc.2021.101274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/17/2021] [Accepted: 09/30/2021] [Indexed: 02/07/2023] Open
Abstract
The ubiquitously expressed transcription factor interferon (IFN) regulatory factor 3 (IRF3) is critical for the induction of antiviral genes, e.g., type-I IFN. In addition to its transcriptional function, IRF3 also activates a nontranscriptional, proapoptotic signaling pathway. While the proapoptotic function of IRF3 protects against viral infections, it is also involved in harmful immune responses that trigger hepatocyte cell death and promote liver disease. Thus, we hypothesized that a small-molecule inhibitor of the proapoptotic activity of IRF3 could alleviate fatty-acid-induced hepatocyte cell death. We conducted a high-throughput screen, which identified auranofin as a small-molecule inhibitor of the proapoptotic activity of IRF3. In addition to the nontranscriptional apoptotic pathway, auranofin also inhibited the transcriptional activity of IRF3. Using biochemical and genetic tools in human and mouse cells, we uncovered a novel mechanism of action for auranofin, in which it induces cellular autophagy to degrade IRF3 protein, thereby suppressing IRF3 functions. Autophagy-deficient cells were unable to degrade IRF3 upon auranofin treatment, suggesting that the autophagic degradation of IRF3 is a novel approach to regulate IRF3 activities. Using a physiologically relevant in vitro model, we demonstrated that auranofin inhibited fatty-acid-induced apoptotic cell death of hepatocytes. In summary, auranofin is a novel inhibitor of IRF3 functions and may represent a potential therapeutic option in diseases where IRF3 is deleterious.
Collapse
Affiliation(s)
- Anna Glanz
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Sukanya Chakravarty
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Shumin Fan
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Karan Chawla
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Gayatri Subramanian
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Tia Rahman
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Dean Walters
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Ritu Chakravarti
- Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Saurabh Chattopadhyay
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA.
| |
Collapse
|
9
|
Transcriptional and Non-Transcriptional Activation, Posttranslational Modifications, and Antiviral Functions of Interferon Regulatory Factor 3 and Viral Antagonism by the SARS-Coronavirus. Viruses 2021; 13:v13040575. [PMID: 33805458 PMCID: PMC8066409 DOI: 10.3390/v13040575] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 12/12/2022] Open
Abstract
The immune system defends against invading pathogens through the rapid activation of innate immune signaling pathways. Interferon regulatory factor 3 (IRF3) is a key transcription factor activated in response to virus infection and is largely responsible for establishing an antiviral state in the infected host. Studies in Irf3−/− mice have demonstrated the absence of IRF3 imparts a high degree of susceptibility to a wide range of viral infections. Virus infection causes the activation of IRF3 to transcribe type-I interferon (e.g., IFNβ), which is responsible for inducing the interferon-stimulated genes (ISGs), which act at specific stages to limit virus replication. In addition to its transcriptional function, IRF3 is also activated to trigger apoptosis of virus-infected cells, as a mechanism to restrict virus spread within the host, in a pathway called RIG-I-like receptor-induced IRF3 mediated pathway of apoptosis (RIPA). These dual functions of IRF3 work in concert to mediate protective immunity against virus infection. These two pathways are activated differentially by the posttranslational modifications (PTMs) of IRF3. Moreover, PTMs regulate not only IRF3 activation and function, but also protein stability. Consequently, many viruses utilize viral proteins or hijack cellular enzymes to inhibit IRF3 functions. This review will describe the PTMs that regulate IRF3′s RIPA and transcriptional activities and use coronavirus as a model virus capable of antagonizing IRF3-mediated innate immune responses. A thorough understanding of the cellular control of IRF3 and the mechanisms that viruses use to subvert this system is critical for developing novel therapies for virus-induced pathologies.
Collapse
|
10
|
Zhou Z, Qi J, Lim CW, Kim JW, Kim B. Dual TBK1/IKKε inhibitor amlexanox mitigates palmitic acid-induced hepatotoxicity and lipoapoptosis in vitro. Toxicology 2020; 444:152579. [PMID: 32905826 DOI: 10.1016/j.tox.2020.152579] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/24/2020] [Accepted: 09/01/2020] [Indexed: 02/08/2023]
Abstract
The common causes of Non-alcoholic fatty liver disease (NAFLD) are obesity, dyslipidemia, and insulin resistance. Metabolic disorders and lipotoxic hepatocyte damage are hallmarks of NAFLD. Even though amlexanox, a dual inhibitor of TRAF associated nuclear factor κB (NF-κB) activator-binding kinase 1 (TBK1) and IκB kinase epsilon (IKKε), has been reported to effectively improve obesity-related metabolic dysfunctions in mice models, its molecular mechanism has not been fully investigated. This study was designed to investigate the effects of amlexanox on in vitro nonalcoholic steatohepatitis (NASH) model induced by treatment of palmitic acid (PA, 0.4 mM), using a trans-well co-culture system of hepatocytes and Kupffer cells (KCs). Stimulation with PA significantly increased the phosphorylation levels of TBK1 and IKKε in both hepatocytes and KCs, suggesting a potential role of TBK1/IKKε in PA-induced NASH progression. Treatment of amlexanox (50 μM) showed significantly reduced phosphorylation of TBK1 and IKKε and hepatotoxicity as confirmed by decreased levels of lactate dehydrogenase released from hepatocytes. Furthermore, PA-induced inflammation and lipotoxic cell death in hepatocytes were significantly reversed by amlexanox treatment. Intriguingly, amlexanox inhibited the activation of KCs and induced polarization of KCs towards M2 phenotype. Mechanistically, amlexanox treatment decreased the phosphorylation of interferon regulator factor 3 (IRF3) and NF-κB in PA-treated hepatocytes. However, decreased phosphorylation of NF-κB, not IRF3, was found in PA-treated KCs upon amlexanox treatment. Taken together, our findings show that treatment of amlexanox attenuated the severity of PA-induced hepatotoxicity in vitro and lipoapoptosis by the inhibition of TBK1/IKKε-NF-κB and/or IRF3 pathway in hepatocytes and KCs.
Collapse
Affiliation(s)
- Zixiong Zhou
- Biosafety Research Institute and Laboratory of Pathology (BK21 Plus Program), College of Veterinary Medicine, Jeonbuk National University, Iksan, 54596, Republic of Korea
| | - Jing Qi
- Biosafety Research Institute and Laboratory of Pathology (BK21 Plus Program), College of Veterinary Medicine, Jeonbuk National University, Iksan, 54596, Republic of Korea
| | - Chae Woong Lim
- Biosafety Research Institute and Laboratory of Pathology (BK21 Plus Program), College of Veterinary Medicine, Jeonbuk National University, Iksan, 54596, Republic of Korea
| | - Jong-Won Kim
- Biosafety Research Institute and Laboratory of Pathology (BK21 Plus Program), College of Veterinary Medicine, Jeonbuk National University, Iksan, 54596, Republic of Korea.
| | - Bumseok Kim
- Biosafety Research Institute and Laboratory of Pathology (BK21 Plus Program), College of Veterinary Medicine, Jeonbuk National University, Iksan, 54596, Republic of Korea.
| |
Collapse
|
11
|
Classical swine fever virus N pro antagonises IRF3 to prevent IFN-independent TLR3 and RIG-I-mediated apoptosis. J Virol 2020; 95:JVI.01136-20. [PMID: 33328306 PMCID: PMC8092839 DOI: 10.1128/jvi.01136-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Classical swine fever virus (CSFV) is the causative agent of classical swine fever, a notifiable disease of economic importance that causes severe leukopenia, fever and haemorrhagic disease in domesticated pigs and wild boar across the globe. CSFV has been shown to antagonise the induction of type I IFN, partly through a function of its N-terminal protease (Npro) which binds IRF3 and targets it for proteasomal degradation. Additionally, Npro has been shown to antagonise apoptosis triggered by the dsRNA-homolog poly(I:C), however the exact mechanism by which this is achieved has not been fully elucidated. In this study we confirm the ability of Npro to inhibit dsRNA-mediated apoptosis and show that Npro is also able to antagonise Sendai virus-mediated apoptosis in PK-15 cells. Gene edited PK-15 cell lines were used to show the dsRNA-sensing pathogen recognition receptors (PRRs) TLR3 and RIG-I specifically respond to poly(I:C) and SeV respectively, subsequently triggering apoptosis through pathways that converge on IRF3 and culminate in the cleavage of caspase-3. Importantly, this IRF3-mediated apoptosis was found to be dependent on transcription-independent functions of IRF3 and also on Bax, a pro-apoptotic Bcl-2 family protein, through a direct interaction between the two proteins. Deletion of IRF3, stable expression of Npro and infection with wild-type CSFV were found to antagonise the mitochondrial localisation of Bax, a key hallmark of the intrinsic, mitochondrial pathway of apoptosis. Together, these findings show that Npro's putative interaction with IRF3 is involved not only in its antagonism of type I IFN, but also dsRNA-mediated mitochondrial apoptosis.Importance Responsible for severe haemorrhagic disease in domestic pigs and wild boar, classical swine fever is recognised by the World Organisation for Animal Health (OIE) and European Union as a notifiable disease of economic importance. Persistent infection, immunotolerance and early dissemination of the virus at local sites of infection have been linked to the antagonism of type I IFN induction by Npro This protein may further contribute to these phenomena by antagonising the induction of dsRNA-mediated apoptosis. Ultimately, apoptosis is an important innate mechanism by which cells counter viruses at local sites of infection, thus preventing wider spread and dissemination within the host, potentially also contributing to the onset of persistence. Elucidation of the mechanism by which Npro antagonises the apoptotic response will help inform the development of rationally-designed live-attenuated vaccines and antivirals for control of outbreaks in typically CSFV-free countries.
Collapse
|
12
|
High Throughput Screening of FDA-Approved Drug Library Reveals the Compounds that Promote IRF3-Mediated Pro-Apoptotic Pathway Inhibit Virus Replication. Viruses 2020; 12:v12040442. [PMID: 32295140 PMCID: PMC7232324 DOI: 10.3390/v12040442] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/06/2020] [Accepted: 04/11/2020] [Indexed: 12/13/2022] Open
Abstract
Interferon (IFN) regulatory factor 3 (IRF3) is the key transcription factor for the induction of IFN and antiviral genes. The absence of antiviral genes in IRF3 deficiency leads to susceptibility to a wide range of viral infections. Previously, we uncovered a function for nontranscriptional IRF3 (nt-IRF3), RLR (RIG-I-like receptor)-induced IRF3-mediated pathway of apoptosis (RIPA), which triggers apoptotic killing of virus-infected cells. Using knock-in mice expressing a transcriptionally inactive, but RIPA-active, IRF3 mutant, we demonstrated the relative contribution of RIPA to host antiviral defense. Given that RIPA is a cellular antiviral pathway, we hypothesized that small molecules that promote RIPA in virus-infected cells would act as antiviral agents. To test this, we conducted a high throughput screen of a library of FDA-approved drugs to identify novel RIPA activators. Our screen identified doxorubicin as a potent RIPA-activating agent. In support of our hypothesis, doxorubicin inhibited the replication of vesicular stomatitis virus, a model rhabdovirus, and its antiviral activity depended on its ability to activate IRF3 in RIPA. Surprisingly, doxorubicin inhibited the transcriptional activity of IRF3. The antiviral activity of doxorubicin was expanded to flavivirus and herpesvirus that also activate IRF3. Mechanistically, doxorubicin promoted RIPA by activating the extracellular signal-regulated kinase (ERK) signaling pathway. Finally, we validated these results using another RIPA-activating compound, pyrvinium pamoate, which showed a similar antiviral effect without affecting the transcriptional activity of IRF3. Therefore, we demonstrate that the RIPA branch of IRF3 can be targeted therapeutically to prevent virus infection.
Collapse
|