1
|
Harris W, Kim S, Vӧlz R, Lee YH. Nuclear effectors of plant pathogens: Distinct strategies to be one step ahead. MOLECULAR PLANT PATHOLOGY 2023; 24:637-650. [PMID: 36942744 DOI: 10.1111/mpp.13315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/17/2023] [Accepted: 02/08/2023] [Indexed: 05/18/2023]
Abstract
Nuclear effector proteins released by bacteria, oomycete, nematode, and fungi burden the global environment and crop yield. Microbial effectors are key weapons in the evolutionary arms race between plants and pathogens, vital in determining the success of pathogenic colonization. Secreted effectors undermine a multitude of host cellular processes depending on their target destination. Effectors are classified by their localization as either extracellular (apoplastic) or intracellular. Intracellular effectors can be further subclassified by their compartment such as the nucleus, cytoplasm or chloroplast. Nuclear effectors bring into question the role of the plant nucleus' intrinsic defence strategies and their vulnerability to effector-based manipulation. Nuclear effectors interfere with multiple nuclear processes including the epigenetic regulation of the host chromatin, the impairment of the trans-kingdom antifungal RNAi machinery, and diverse classes of immunity-associated host proteins. These effector-targeted pathways are widely conserved among different hosts and regulate a broad array of plant cellular processes. Thus, these nuclear sites constitute meaningful targets for effectors to subvert the plant defence system and acquire resources for pathogenic propagation. This review provides an extensive and comparative compilation of diverse plant microbe nuclear effector libraries, thereby highlighting the distinct and conserved mechanisms these effectors employ to modulate plant cellular processes for the pathogen's profit.
Collapse
Affiliation(s)
- William Harris
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
| | - Seongbeom Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
| | - Ronny Vӧlz
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
| | - Yong-Hwan Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
- Interdisciplinary Program in Agricultural Genomics, Seoul National University, Seoul, South Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
- Center for Fungal Genetic Resources, Seoul National University, Seoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, South Korea
- Plant Immunity Research Center, Seoul National University, Seoul, South Korea
- Center for Plant Microbiome Research, Seoul National University, Seoul, South Korea
| |
Collapse
|
2
|
Liu BR, Chen CW, Huang YW, Lee HJ. Cell-Penetrating Peptides for Use in Development of Transgenic Plants. Molecules 2023; 28:molecules28083367. [PMID: 37110602 PMCID: PMC10142301 DOI: 10.3390/molecules28083367] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 03/24/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
Genetically modified plants and crops can contribute to remarkable increase in global food supply, with improved yield and resistance to plant diseases or insect pests. The development of biotechnology introducing exogenous nucleic acids in transgenic plants is important for plant health management. Different genetic engineering methods for DNA delivery, such as biolistic methods, Agrobacterium tumefaciens-mediated transformation, and other physicochemical methods have been developed to improve translocation across the plasma membrane and cell wall in plants. Recently, the peptide-based gene delivery system, mediated by cell-penetrating peptides (CPPs), has been regarded as a promising non-viral tool for efficient and stable gene transfection into both animal and plant cells. CPPs are short peptides with diverse sequences and functionalities, capable of agitating plasma membrane and entering cells. Here, we highlight recent research and ideas on diverse types of CPPs, which have been applied in DNA delivery in plants. Various basic, amphipathic, cyclic, and branched CPPs were designed, and modifications of functional groups were performed to enhance DNA interaction and stabilization in transgenesis. CPPs were able to carry cargoes in either a covalent or noncovalent manner and to internalize CPP/cargo complexes into cells by either direct membrane translocation or endocytosis. Importantly, subcellular targets of CPP-mediated nucleic acid delivery were reviewed. CPPs offer transfection strategies and influence transgene expression at subcellular localizations, such as in plastids, mitochondria, and the nucleus. In summary, the technology of CPP-mediated gene delivery provides a potent and useful tool to genetically modified plants and crops of the future.
Collapse
Affiliation(s)
- Betty Revon Liu
- Department of Laboratory Medicine and Biotechnology, College of Medicine, Tzu Chi University, Hualien 970374, Taiwan
| | - Chi-Wei Chen
- Department of Life Science, College of Science and Engineering, National Dong Hwa University, Hualien 974301, Taiwan
| | - Yue-Wern Huang
- Department of Biological Sciences, College of Arts, Sciences, and Education, Missouri University of Science and Technology, Rolla, MO 65409, USA
| | - Han-Jung Lee
- Department of Natural Resources and Environmental Studies, College of Environmental Studies and Oceanography, National Dong Hwa University, Hualien 974301, Taiwan
| |
Collapse
|
3
|
Mattola S, Aho V, Bustamante‐Jaramillo LF, Pizzioli E, Kann M, Vihinen‐Ranta M. Nuclear entry and egress of parvoviruses. Mol Microbiol 2022; 118:295-308. [PMID: 35974704 PMCID: PMC9805091 DOI: 10.1111/mmi.14974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/10/2022] [Accepted: 08/13/2022] [Indexed: 01/09/2023]
Abstract
Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18-26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed by currently undefined events of viral genome uncoating. After genome release, viral replication compartments are initiated and infection proceeds. Parvoviral genomes replicate during cellular S phase followed by nuclear capsid assembly during virus-induced S/G2 cell cycle arrest. Nuclear egress of capsids occurs upon nuclear envelope degradation during apoptosis and cell lysis. An alternative pathway for nuclear export has been described using active transport through the NPC mediated by the chromosome region maintenance 1 protein, CRM1, which is enhanced by phosphorylation of the N-terminal domain of VP2. However, other alternative but not yet uncharacterized nuclear export pathways cannot be excluded.
Collapse
Affiliation(s)
- Salla Mattola
- Department of Biological and Environmental ScienceUniversity of JyvaskylaJyvaskylaFinland
| | - Vesa Aho
- Department of Biological and Environmental ScienceUniversity of JyvaskylaJyvaskylaFinland
| | | | - Edoardo Pizzioli
- Department of Infectious Diseases, Institute of BiomedicineUniversity of GothenburgGothenburgSweden
| | - Michael Kann
- Department of Infectious Diseases, Institute of BiomedicineUniversity of GothenburgGothenburgSweden,Sahlgrenska AcademyGothenburgSweden,Department of Clinical MicrobiologyRegion Västra Götaland, Sahlgrenska University HospitalGothenburgSweden
| | - Maija Vihinen‐Ranta
- Department of Biological and Environmental ScienceUniversity of JyvaskylaJyvaskylaFinland
| |
Collapse
|
4
|
ADAP restraint of STAT1 signaling regulates macrophage phagocytosis in immune thrombocytopenia. Cell Mol Immunol 2022; 19:898-912. [PMID: 35637282 PMCID: PMC9149338 DOI: 10.1038/s41423-022-00881-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 05/09/2022] [Indexed: 01/08/2023] Open
Abstract
Heightened platelet phagocytosis by macrophages accompanied by an increase in IFN-γ play key roles in the etiology of immune thrombocytopenia (ITP); however, it remains elusive how macrophage-mediated platelet clearance is regulated in ITP. Here, we report that adhesion and degranulation-protein adaptor protein (ADAP) restrains platelet phagocytosis by macrophages in ITP via modulation of signal transducer and activator of transcription 1 (STAT1)-FcγR signaling. We show that ITP was associated with the underexpression of ADAP in splenic macrophages. Furthermore, macrophages from Adap−/− mice exhibited elevated platelet phagocytosis and upregulated proinflammatory signaling, and thrombocytopenia in Adap−/− mice was mitigated by the depletion of macrophages. Mechanistically, ADAP interacted and competed with STAT1 binding to importin α5. ADAP deficiency potentiated STAT1 nuclear entry, leading to a selective enhancement of FcγRI/IV transcription in macrophages. Moreover, pharmacological inhibition of STAT1 or disruption of the STAT1-importin α5 interaction relieved thrombocytopenia in Adap−/− mice. Thus, our findings not only reveal a critical role for ADAP as an intracellular immune checkpoint for shaping macrophage phagocytosis in ITP but also identify the ADAP-STAT1-importin α5 module as a promising therapeutic target in the treatment of ITP.
Collapse
|
5
|
STAT1 and Its Crucial Role in the Control of Viral Infections. Int J Mol Sci 2022; 23:ijms23084095. [PMID: 35456913 PMCID: PMC9028532 DOI: 10.3390/ijms23084095] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/31/2022] [Accepted: 04/05/2022] [Indexed: 02/04/2023] Open
Abstract
The signal transducer and activator of transcription (STAT) 1 protein plays a key role in the immune response against viruses and other pathogens by transducing, in the nucleus, the signal from type I, type II and type III IFNs. STAT1 activates the transcription of hundreds of genes, some of which have been well characterized for their antiviral properties. STAT1 gene deletion in mice and complete STAT1 deficiency in humans both cause rapid death from severe infections. STAT1 plays a key role in the immunoglobulin class-switch recombination through the upregulation of T-bet; it also plays a key role in the production of T-bet+ memory B cells that contribute to tissue-resident humoral memory by mounting an IgG response during re-infection. Considering the key role of STAT1 in the antiviral immune response, many viruses, including dangerous viruses such as Ebola and SARS-CoV-2, have developed different mechanisms to inhibit this transcription factor. The search for drugs capable of targeting the viral proteins implicated in both viral replication and IFN/STAT1 inhibition is important for the treatment of the most dangerous viral infections and for future viral pandemics, as shown by the clinical results obtained with Paxlovid in patients infected with SARS-CoV-2.
Collapse
|
6
|
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.
Collapse
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.
| |
Collapse
|
7
|
Erdogan F, Qadree AK, Radu TB, Orlova A, de Araujo ED, Israelian J, Valent P, Mustjoki SM, Herling M, Moriggl R, Gunning PT. Structural and mutational analysis of member-specific STAT functions. Biochim Biophys Acta Gen Subj 2022; 1866:130058. [PMID: 34774983 DOI: 10.1016/j.bbagen.2021.130058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/29/2021] [Accepted: 11/05/2021] [Indexed: 12/21/2022]
Abstract
BACKGROUND The STAT family of transcription factors control gene expression in response to signals from various stimulus. They display functions in diseases ranging from autoimmunity and chronic inflammatory disease to cancer and infectious disease. SCOPE OF REVIEW This work uses an approach informed by structural data to explore how domain-specific structural variations, post-translational modifications, and the cancer genome mutational landscape dictate STAT member-specific activities. MAJOR CONCLUSIONS We illustrated the structure-function relationship of STAT proteins and highlighted their effect on member-specific activity. We correlated disease-linked STAT mutations to the structure and cancer genome mutational landscape and proposed rational drug targeting approaches of oncogenic STAT pathway addiction. GENERAL SIGNIFICANCE Hyper-activated STATs and their variants are associated with multiple diseases and are considered high value oncology targets. A full understanding of the molecular basis of member-specific STAT-mediated signaling and the strategies to selectively target them requires examination of the difference in their structures and sequences.
Collapse
Affiliation(s)
- Fettah Erdogan
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Abdul K Qadree
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Tudor B Radu
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Anna Orlova
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, A-1210 Vienna, Austria
| | - Elvin D de Araujo
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada
| | - Johan Israelian
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Peter Valent
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, Vienna, Austria
| | - Satu M Mustjoki
- Hematology Research Unit, Helsinki University Hospital Comprehensive Cancer Center, Helsinki, Finland; Translational Immunology Research Program and Department of Clinical Chemistry and Hematology, University of Helsinki, Helsinki, Finland; iCAN Digital Precision Cancer Medicine Flagship, Helsinki, Finland
| | - Marco Herling
- Department of Hematology, Cellular Therapy, and Hemostaseology, University of Leipzig, Leipzig, Germany
| | - Richard Moriggl
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, A-1210 Vienna, Austria
| | - Patrick T Gunning
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada.
| |
Collapse
|
8
|
He FB, Khan H, Huttunen M, Kolehmainen P, Melén K, Maljanen S, Qu M, Jiang M, Kakkola L, Julkunen I. Filovirus VP24 Proteins Differentially Regulate RIG-I and MDA5-Dependent Type I and III Interferon Promoter Activation. Front Immunol 2022; 12:694105. [PMID: 35069519 PMCID: PMC8767557 DOI: 10.3389/fimmu.2021.694105] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 12/14/2021] [Indexed: 12/24/2022] Open
Abstract
Filovirus family consists of highly pathogenic viruses that have caused fatal outbreaks especially in many African countries. Previously, research focus has been on Ebola, Sudan and Marburg viruses leaving other filoviruses less well studied. Filoviruses, in general, pose a significant global threat since they are highly virulent and potentially transmissible between humans causing sporadic infections and local or widespread epidemics. Filoviruses have the ability to downregulate innate immunity, and especially viral protein 24 (VP24), VP35 and VP40 have variably been shown to interfere with interferon (IFN) gene expression and signaling. Here we systematically analyzed the ability of VP24 proteins of nine filovirus family members to interfere with retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated antigen 5 (MDA5) induced IFN-β and IFN-λ1 promoter activation. All VP24 proteins were localized both in the cell cytoplasm and nucleus in variable amounts. VP24 proteins of Zaire and Sudan ebolaviruses, Lloviu, Taï Forest, Reston, Marburg and Bundibugyo viruses (EBOV, SUDV, LLOV, TAFV, RESTV, MARV and BDBV, respectively) were found to inhibit both RIG-I and MDA5 stimulated IFN-β and IFN-λ1 promoter activation. The inhibition takes place downstream of interferon regulatory factor 3 phosphorylation suggesting the inhibition to occur in the nucleus. VP24 proteins of Mengla (MLAV) or Bombali viruses (BOMV) did not inhibit IFN-β or IFN-λ1 promoter activation. Six ebolavirus VP24s and Lloviu VP24 bound tightly, whereas MARV and MLAV VP24s bound weakly, to importin α5, the subtype that regulates the nuclear import of STAT complexes. MARV and MLAV VP24 binding to importin α5 was very weak. Our data provides new information on the innate immune inhibitory mechanisms of filovirus VP24 proteins, which may contribute to the pathogenesis of filovirus infections.
Collapse
Affiliation(s)
- Felix B. He
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
| | - Hira Khan
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
| | - Moona Huttunen
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
| | - Pekka Kolehmainen
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
| | - Krister Melén
- Expert Microbiology Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Sari Maljanen
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
| | - Mengmeng Qu
- Research Center for Clinical & Translational Medicine, Fifth Medical Center for General Hospital of People’s Liberation Army (PLA), Beijing, China
| | - Miao Jiang
- Expert Microbiology Unit, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Laura Kakkola
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
| | - Ilkka Julkunen
- Institute of Biomedicine/Virology, University of Turku, Turku, Finland
- Turku University Hospital, Clinical Microbiology, Turku, Finland
| |
Collapse
|
9
|
Tarvirdipour S, Skowicki M, Schoenenberger CA, Kapinos LE, Lim R, Benenson Y, Palivan CG. A self-assembling peptidic platform to boost the cellular uptake and nuclear delivery of oligonucleotides. Biomater Sci 2022; 10:4309-4323. [DOI: 10.1039/d2bm00826b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The design of non-viral vectors that efficiently deliver genetic materials into cells, in particular to the nucleus, remains a major challenge in gene therapy and vaccine development. To tackle the...
Collapse
|
10
|
Wang Y, Liu R, Liao J, Jiang L, Jeong GH, Zhou L, Polite M, Duong D, Seyfried NT, Wang H, Kiyokawa H, Yin J. Orthogonal ubiquitin transfer reveals human papillomavirus E6 downregulates nuclear transport to disarm interferon-γ dependent apoptosis of cervical cancer cells. FASEB J 2021; 35:e21986. [PMID: 34662469 DOI: 10.1096/fj.202101232rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 02/05/2023]
Abstract
The E6 protein of the human papillomavirus (HPV) underpins important protein interaction networks between the virus and host to promote viral infection. Through its interaction with E6AP, a host E3 ubiquitin (UB) ligase, E6 stirs the protein ubiquitination pathways toward the oncogenic transformation of the infected cells. For a systematic measurement of E6 reprogramming of the substrate pool of E6AP, we performed a proteomic screen based on "orthogonal UB transfer (OUT)" that allowed us to identify the ubiquitination targets of E6AP dependent on the E6 protein of HPV-16, a high-risk viral subtype for the development of cervical cancer. The OUT screen identified more than 200 potential substrates of the E6-E6AP pair based on the transfer of UB from E6AP to the substrate proteins. Among them, we verified that E6 would induce E6AP-catalyzed ubiquitination of importin proteins KPNA1-3, protein phosphatase PGAM5, and arginine methyltransferases CARM1 to trigger their degradation by the proteasome. We further found that E6 could significantly reduce the cellular level of KPNA1 that resulted in the suppression of nuclear transport of phosphorylated STAT1 and the inhibition of interferon-γ-induced apoptosis in cervical cancer cells. Overall, our work demonstrates OUT as a powerful proteomic platform to probe the interaction of E6 and host cells through protein ubiquitination and reveals a new role of E6 in down-regulating nuclear transport proteins to attenuate tumor-suppressive signaling.
Collapse
Affiliation(s)
- Yiyang Wang
- Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Ruochuan Liu
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Jia Liao
- Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China
| | - Lucen Jiang
- Department of Pathology, The Third Affiliated Hospital of Southern Medical University, Guangzhou, China
| | - Geon H Jeong
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Li Zhou
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Monica Polite
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Duc Duong
- Integrated Proteomics Core, Emory University, Atlanta, Georgia, USA
| | - Nicholas T Seyfried
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Huadong Wang
- Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, China
| | - Hiroaki Kiyokawa
- Department of Pharmacology, Northwestern University, Chicago, Illinois, USA
| | - Jun Yin
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA
| |
Collapse
|
11
|
Grabarczyk P, Delin M, Rogińska D, Schulig L, Forkel H, Depke M, Link A, Machaliński B, Schmidt CA. Nuclear import of BCL11B is mediated by a classical nuclear localization signal and not the Krüppel-like zinc fingers. J Cell Sci 2021; 134:272659. [PMID: 34714335 DOI: 10.1242/jcs.258655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 10/24/2021] [Indexed: 11/20/2022] Open
Abstract
The Krüppel-like transcription factor BCL11B is characterized by wide tissue distribution and crucial functions in key developmental and cellular processes and various pathologies including cancer or HIV infection. Although basics of BCL11B activity and relevant interactions with other proteins were uncovered, how this exclusively nuclear protein localizes to its compartment remained unclear. Here, we demonstrate that unlike other KLFs, BCL11B does not require the C-terminal DNA-binding domain to pass through the nuclear envelope but encodes an independent, previously unidentified nuclear localization signal (NLS) which is located distantly from the zinc finger domains and fulfills the essential criteria of an autonomous NLS. First, it can redirect a heterologous cytoplasmic protein to the nucleus. Second, its mutations cause aberrant localization of the protein of origin. Finally, we provide experimental and in silico evidences of the direct interaction with importin alpha. The relative conservation of this motif allows formulating a consensus sequence (K/R)K-X13-14-KR+K++ which can be found in all BCL11B orthologues among vertebrates and in the closely related protein BCL11A.
Collapse
Affiliation(s)
- Piotr Grabarczyk
- Clinic of Hematology and Oncology, University Medicine Greifswald, Greifswald, Germany
| | - Martin Delin
- Clinic of Hematology and Oncology, University Medicine Greifswald, Greifswald, Germany
| | - Dorota Rogińska
- Department of General Pathology, Pomeranian Medical University, Szczecin, Poland
| | - Lukas Schulig
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Hannes Forkel
- Clinic of Hematology and Oncology, University Medicine Greifswald, Greifswald, Germany
| | - Maren Depke
- Clinic of Hematology and Oncology, University Medicine Greifswald, Greifswald, Germany
| | - Andreas Link
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Bogusław Machaliński
- Department of General Pathology, Pomeranian Medical University, Szczecin, Poland
| | | |
Collapse
|
12
|
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: 27] [Impact Index Per Article: 9.0] [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.
Collapse
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.
| |
Collapse
|
13
|
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: 130] [Impact Index Per Article: 43.3] [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.
Collapse
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
| |
Collapse
|
14
|
Le LHM, Ying L, Ferrero RL. Nuclear trafficking of bacterial effector proteins. Cell Microbiol 2021; 23:e13320. [PMID: 33600054 DOI: 10.1111/cmi.13320] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens can subvert host responses by producing effector proteins that directly target the nucleus of eukaryotic cells in animals and plants. Nuclear-targeting proteins are categorised as either: "nucleomodulins," which have epigenetic-modulating activities; or "cyclomodulins," which specifically interfere with the host cell cycle. Bacteria can deliver these effector proteins to eukaryotic cells via a range of strategies. Despite an increasing number of reports describing the effects of bacterial effector proteins on nuclear processes in host cells, the intracellular pathways used by these proteins to traffic to the nucleus have yet to be fully elucidated. This review will describe current knowledge about how nucleomodulins and cyclomodulins enter eukaryotic cells, exploit endocytic pathways and translocate to the nucleus. We will also discuss the secretion of nuclear-targeting proteins or their release in bacterial membrane vesicles and the trafficking pathways employed by each of these forms. Besides their importance for bacterial pathogenesis, some nuclear-targeting proteins have been implicated in the development of chronic diseases and even cancer. A greater understanding of nuclear-targeting proteins and their actions will provide new insights into the pathogenesis of infectious diseases, as well as contribute to advances in the development of novel therapies against bacterial infections and possibly cancer.
Collapse
Affiliation(s)
- Lena Hoang My Le
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Biomedicine Discovery Institute, Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Le Ying
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Richard L Ferrero
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Biomedicine Discovery Institute, Department of Microbiology, Monash University, Melbourne, Victoria, Australia.,Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia
| |
Collapse
|
15
|
Banik S, Rakshit S, Sarkar K. The Role of STAT1 in T Helper Cell Differentiation during Breast Cancer Progression. J Breast Cancer 2021; 24:253-265. [PMID: 34190440 PMCID: PMC8250105 DOI: 10.4048/jbc.2021.24.e34] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 03/25/2021] [Accepted: 05/02/2021] [Indexed: 01/10/2023] Open
Abstract
Members of the signal transducer and activator of transcription (STAT) protein family are intracellular transcription factors that facilitate several facets of cellular immunity, proliferation, apoptosis, and differentiation. They are principally stimulated by membrane receptor-associated Janus kinases. Dysregulation of this pathway is often detected in primary tumors and hints at augmented angiogenesis, which enriches tumors persistence and immunosuppression. STAT proteins play indispensable roles in cytokine signaling and T helper (Th) cell differentiation. Among STAT proteins, STAT1 plays a vital role in interferon signaling, which initiates the expression of genes encoding proteins with antitumor and apoptotic roles. STAT1 signaling is essential for Th1 cell differentiation. Several studies have also shown the role of STAT1 as a tumor suppressor in breast cancer, which is the most common intrusive malignancy and the second most common cause of cancer death in women. Herein, we review the intricate STAT1-mediated molecular mechanisms associated with Th cell differentiation and anti-tumor function in breast cancer.
Collapse
Affiliation(s)
- Sayantan Banik
- Department of Biotechnology, SRM Institute of Science and Technology, Kattankulathur, India
| | - Sudeshna Rakshit
- Department of Biotechnology, SRM Institute of Science and Technology, Kattankulathur, India
| | - Koustav Sarkar
- Department of Biotechnology, SRM Institute of Science and Technology, Kattankulathur, India.
| |
Collapse
|
16
|
Ahmad I, Valverde A, Siddiqui H, Schaller S, Naqvi AR. Viral MicroRNAs: Interfering the Interferon Signaling. Curr Pharm Des 2020; 26:446-454. [PMID: 31924149 DOI: 10.2174/1381612826666200109181238] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 12/22/2019] [Indexed: 12/23/2022]
Abstract
Interferons are secreted cytokines with potent antiviral, antitumor and immunomodulatory functions. As the first line of defense against viruses, this pathway restricts virus infection and spread. On the contrary, viruses have evolved ingenious strategies to evade host immune responses including the interferon pathway. Multiple families of viruses, in particular, DNA viruses, encode microRNA (miR) that are small, non-protein coding, regulatory RNAs. Virus-derived miRNAs (v-miR) function by targeting host and virus-encoded transcripts and are critical in shaping host-pathogen interaction. The role of v-miRs in viral pathogenesis is emerging as demonstrated by their function in subverting host defense mechanisms and regulating fundamental biological processes such as cell survival, proliferation, modulation of viral life-cycle phase. In this review, we will discuss the role of v-miRs in the suppression of host genes involved in the viral nucleic acid detection, JAK-STAT pathway, and cytokine-mediated antiviral gene activation to favor viral replication and persistence. This information has yielded new insights into our understanding of how v-miRs promote viral evasion of host immunity and likely provide novel antiviral therapeutic targets.
Collapse
Affiliation(s)
- Imran Ahmad
- Mucosal Immunology Lab, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, IL 60612, United States
| | - Araceli Valverde
- Mucosal Immunology Lab, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, IL 60612, United States
| | - Hasan Siddiqui
- Mucosal Immunology Lab, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, IL 60612, United States
| | - Samantha Schaller
- Mucosal Immunology Lab, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, IL 60612, United States
| | - Afsar R Naqvi
- Mucosal Immunology Lab, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, IL 60612, United States
| |
Collapse
|
17
|
Staab J, Schwämmle T, Meyer T. The pathogenic T387A missense mutation in the gene encoding signal transducer and activator of transcription 1 exhibits a differential gene expression profile. Mol Immunol 2020; 128:79-88. [PMID: 33096415 DOI: 10.1016/j.molimm.2020.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/07/2020] [Indexed: 11/17/2022]
Abstract
Heterozygous gain-of-function (GOF) mutations in the interferon-driven transcription factor STAT1 (signal transducer and activator of transcription 1) cause chronic mucocutaneous candidiasis (CMC). In this study, we characterized the molecular basis of a CMC-associated missense mutation by introducing a threonine-to-alanine exchange in the STAT1 DNA-binding domain at position 387. This substitution had previously been described in a CMC patient with suppurative eyelid infection and cutaneous abscesses, which are both unusual symptoms in this immunodeficiency. The STAT1-T387A mutant generated was compared to the wild-type protein and, in addition, to the missense mutant in the neighbouring position 386. Our results showed that the T387A mutant displayed distinct properties different from the wild-type molecule, namely elevated levels of tyrosine phosphorylation in conjunction with increased DNA-binding activity, hyperactive transcriptional regulation, and prolonged nuclear accumulation. The elevated tyrosine phosphorylation of the T387A mutant did not result in an increased mRNA production above the level of the wild-type molecule for all transcripts tested, indicating that the transcriptional activity of this mutant is largely gene-dependent. Nonetheless, these data demonstrate that the pathogenic T387A mutation associated with an atypical CMC symptomatology is biochemically similar to other well-characterized GOF mutants, while the H386A mutant was indistinguishable from the wild-type molecule. Our findings are in line with the assumption that the phenotype of this dominant STAT1 GOF mutation probably results from a disturbed shift in the equilibrium between the parallel and antiparallel dimer conformation, which is required for physiological gene activation.
Collapse
Affiliation(s)
- Julia Staab
- Department of Psychosomatic Medicine and Psychotherapy, University of Göttingen, Göttingen, Germany; German Center for Cardiovascular Research (DZHK), partner site Göttingen, Germany
| | - Till Schwämmle
- Department of Psychosomatic Medicine and Psychotherapy, University of Göttingen, Göttingen, Germany; Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Thomas Meyer
- Department of Psychosomatic Medicine and Psychotherapy, University of Göttingen, Göttingen, Germany; German Center for Cardiovascular Research (DZHK), partner site Göttingen, Germany.
| |
Collapse
|
18
|
Luthra P, Anantpadma M, De S, Sourimant J, Davey RA, Plemper RK, Basler CF. High-Throughput Screening Assay to Identify Small Molecule Inhibitors of Marburg Virus VP40 Protein. ACS Infect Dis 2020; 6:2783-2799. [PMID: 32870648 DOI: 10.1021/acsinfecdis.0c00512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Marburg virus (MARV) causes sporadic outbreaks of severe disease with high case fatality rates in humans. To date, neither therapeutics nor prophylactic approaches have been approved for MARV disease. The MARV matrix protein VP40 (mVP40) plays central roles in virus assembly and budding. mVP40 also inhibits interferon signaling by inhibiting the function of Janus kinase 1. This suppression of host antiviral defenses likely contributes to MARV virulence and therefore is a potential therapeutic target. We developed and optimized a cell-based high-throughput screening (HTS) assay in 384-well format to measure mVP40 interferon (IFN) antagonist function such that inhibitors could be identified. We performed a pilot screen of 1280 bioactive compounds and identified 3 hits, azaguanine-8, tosufloxacin hydrochloride, and linezolid, with Z scores > 3 and no significant cytotoxicity. Of these, azaguanine-8 inhibited MARV growth at noncytotoxic concentrations. These data demonstrate the suitability of the HTS mVP40 assay for drug discovery and suggest potential directions for anti-MARV therapeutic development.
Collapse
Affiliation(s)
- Priya Luthra
- Trudeau Institute, Saranac Lake, New York 12983-2100, United States
| | - Manu Anantpadma
- WuXi App Tec, Philadelphia, Pennsylvania 19112, United States
| | - Sampriti De
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Julien Sourimant
- Center for Inflammation, Immunity and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Robert A. Davey
- National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts 02118, United States
| | - Richard K. Plemper
- Center for Inflammation, Immunity and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Christopher F. Basler
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia 30302-3965, United States
| |
Collapse
|
19
|
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.
Collapse
|
20
|
Renz P, Imahorn E, Spoerri I, Aushev M, March OP, Wariwoda H, Von Arb S, Volz A, Itin PH, Reichelt J, Burger B. Arginine- but not alanine-rich carboxy-termini trigger nuclear translocation of mutant keratin 10 in ichthyosis with confetti. J Cell Mol Med 2019; 23:8442-8452. [PMID: 31638346 PMCID: PMC6850952 DOI: 10.1111/jcmm.14727] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/04/2019] [Accepted: 09/06/2019] [Indexed: 11/30/2022] Open
Abstract
Ichthyosis with confetti (IWC) is a genodermatosis associated with dominant-negative variants in keratin 10 (KRT10) or keratin 1 (KRT1). These frameshift variants result in extended aberrant proteins, localized to the nucleus rather than the cytoplasm. This mislocalization is thought to occur as a result of the altered carboxy (C)-terminus, from poly-glycine to either a poly-arginine or -alanine tail. Previous studies on the type of C-terminus and subcellular localization of the respective mutant protein are divergent. In order to fully elucidate the pathomechanism of IWC, a greater understanding is critical. This study aimed to establish the consequences for localization and intermediate filament formation of altered keratin 10 (K10) C-termini. To achieve this, plasmids expressing distinct KRT10 variants were generated. Sequences encoded all possible reading frames of the K10 C-terminus as well as a nonsense variant. A keratinocyte line was transfected with these plasmids. Additionally, gene editing was utilized to introduce frameshift variants in exon 6 and exon 7 at the endogenous KRT10 locus. Cellular localization of aberrant K10 was observed via immunofluorescence using various antibodies. In each setting, immunofluorescence analysis demonstrated aberrant nuclear localization of K10 featuring an arginine-rich C-terminus. However, this was not observed with K10 featuring an alanine-rich C-terminus. Instead, the protein displayed cytoplasmic localization, consistent with wild-type and truncated forms of K10. This study demonstrates that, of the various 3' frameshift variants of KRT10, exclusively arginine-rich C-termini lead to nuclear localization of K10.
Collapse
Affiliation(s)
- Patricia Renz
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
| | - Elias Imahorn
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
| | - Iris Spoerri
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
| | - Magomet Aushev
- Wellcome Centre for Mitochondrial ResearchInstitute of Genetic MedicineNewcastle upon TyneUK
| | - Oliver P. March
- Department of DermatologyEB House AustriaUniversity Hospital of the Paracelsus Medical UniversitySalzburgAustria
| | - Hedwig Wariwoda
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
| | - Sarah Von Arb
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
| | - Andreas Volz
- DermatologyUniversity Hospital BaselBaselSwitzerland
| | - Peter H. Itin
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
- DermatologyUniversity Hospital BaselBaselSwitzerland
| | - Julia Reichelt
- Department of DermatologyEB House AustriaUniversity Hospital of the Paracelsus Medical UniversitySalzburgAustria
| | - Bettina Burger
- Department of BiomedicineUniversity Hospital Basel and University of BaselBaselSwitzerland
| |
Collapse
|
21
|
Mou C, Wang M, Pan S, Chen Z. Identification of Nuclear Localization Signals in the ORF2 Protein of Porcine Circovirus Type 3. Viruses 2019; 11:v11121086. [PMID: 31766638 PMCID: PMC6950156 DOI: 10.3390/v11121086] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 11/16/2022] Open
Abstract
Porcine circovirus type 3 (PCV3) contains two major open reading frames (ORFs) and the ORF2 gene encodes the major structural capsid protein. In this study, nuclear localization of ORF2 was demonstrated by fluorescence observation and subcellular fractionation assays in ORF2-transfected PK-15 cells. The subcellular localization of truncated ORF2 indicated that the 38 N-terminal amino acids were responsible for the nuclear localization of ORF2. The truncated and site-directed mutagenesis of this domain were constructed, and the results demonstrated that the basic amino acid residues at positions 8-32 were essential for the strict nuclear localization. The basic motifs 8RRR-R-RRR16 and 16RRRHRRR22 were further shown to be the key functional nucleolar localization signals that guide PCV3 ORF2 into nucleoli. Furthermore, sequence analysis showed that the amino acids of PCV3 nuclear localization signals were highly conserved. Overall, this study provides insight into the biological and functional characteristics of the PCV3 ORF2 protein.
Collapse
Affiliation(s)
- Chunxiao Mou
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (C.M.); (S.P.)
| | - Minmin Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (C.M.); (S.P.)
| | - Shuonan Pan
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (C.M.); (S.P.)
| | - Zhenhai Chen
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (C.M.); (S.P.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou 225009, China
- Correspondence: ; Tel.: +86-182-5274-7459 or +86-514-8979-8271; Fax: 0514-8797-2218
| |
Collapse
|
22
|
Ernst S, Müller-Newen G. Nucleocytoplasmic Shuttling of STATs. A Target for Intervention? Cancers (Basel) 2019; 11:cancers11111815. [PMID: 31752278 PMCID: PMC6895884 DOI: 10.3390/cancers11111815] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/08/2019] [Accepted: 11/13/2019] [Indexed: 12/12/2022] Open
Abstract
Signal transducer and activator of transcription (STAT) proteins are transcription factors that in the latent state are located predominantly in the cytoplasm. Activation of STATs through phosphorylation of a single tyrosine residue results in nuclear translocation. The requirement of tyrosine phosphorylation for nuclear accumulation is shared by all STAT family members but mechanisms of nuclear translocation vary between different STATs. These differences offer opportunities for specific intervention. To achieve this, the molecular mechanisms of nucleocytoplasmic shuttling of STATs need to be understood in more detail. In this review we will give an overview on the various aspects of nucleocytoplasmic shuttling of latent and activated STATs with a special focus on STAT3 and STAT5. Potential targets for cancer treatment will be identified and discussed.
Collapse
Affiliation(s)
- Sabrina Ernst
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, 52074 Aachen, Germany;
- Confocal Microscopy Facility, Interdisciplinary Center for Clinical Research IZKF, RWTH Aachen University, 52074 Aachen, Germany
| | - Gerhard Müller-Newen
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, 52074 Aachen, Germany;
- Correspondence:
| |
Collapse
|
23
|
Louzoun‐Zada S, Jaber QZ, Fridman M. Guiding Drugs to Target‐Harboring Organelles: Stretching Drug‐Delivery to a Higher Level of Resolution. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906284] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Sivan Louzoun‐Zada
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences Tel Aviv University Tel Aviv 6997801 Israel
| | - Qais Z. Jaber
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences Tel Aviv University Tel Aviv 6997801 Israel
| | - Micha Fridman
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences Tel Aviv University Tel Aviv 6997801 Israel
| |
Collapse
|
24
|
Louzoun-Zada S, Jaber QZ, Fridman M. Guiding Drugs to Target-Harboring Organelles: Stretching Drug-Delivery to a Higher Level of Resolution. Angew Chem Int Ed Engl 2019; 58:15584-15594. [PMID: 31237741 DOI: 10.1002/anie.201906284] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Indexed: 01/04/2023]
Abstract
The ratio between the dose of drug required for optimal efficacy and the dose that causes toxicity is referred to as the therapeutic window. This ratio can be increased by directing the drug to the diseased tissue or pathogenic cell. For drugs targeting fungi and malignant cells, the therapeutic window can be further improved by increasing the resolution of drug delivery to the specific organelle that harbors the drug's target. Organelle targeting is challenging and is, therefore, an under-exploited strategy. Here we provide an overview of recent advances in control of the subcellular distribution of small molecules with the focus on chemical modifications. Highlighted are recent examples of active and passive organelle-specific targeting by incorporation of organelle-directing molecular determinants or by chemical modifications of the pharmacophore. The outstanding potential that lies in the development of organelle-specific drugs is becoming increasingly apparent.
Collapse
Affiliation(s)
- Sivan Louzoun-Zada
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Qais Z Jaber
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Micha Fridman
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| |
Collapse
|
25
|
Fang C, Li J, Qi S, Lei Y, Zeng Y, Yu P, Hu Z, Zhou Y, Wang Y, Dai R, Li J, Huang S, Xu P, Chen K, Ding C, Yu FX. An alternatively transcribed TAZ variant negatively regulates JAK-STAT signaling. EMBO Rep 2019; 20:embr.201847227. [PMID: 30979708 DOI: 10.15252/embr.201847227] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/25/2019] [Accepted: 03/25/2019] [Indexed: 12/11/2022] Open
Abstract
Type I interferon (IFN)-induced Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling drives the expression of IFN-stimulated genes (ISGs) to mediate antiviral response. The strength and duration of JAK-STAT signaling are tightly regulated to ensure effective antiviral defense while avoiding pathological inflammation and autoimmunity. Here, we report that cTAZ, an isoform of the Hippo pathway effector TAZ, is transcribed by an alternative promoter. Although majority of C-terminal sequences of TAZ is retained, cTAZ is not regulated by the Hippo signaling and does not mediate its growth-inhibitory functions. Instead, cTAZ negatively regulates JAK-STAT signaling by inhibiting STAT1/2 nuclear localization and ISG expression, and its expression is induced by type I IFN Thus, cTAZ functions as a modulator of JAK-STAT signaling and may play a role in fine-tuning cellular antiviral response.
Collapse
Affiliation(s)
- Chuantao Fang
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Jian Li
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Sixian Qi
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Yubin Lei
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Yan Zeng
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Pengcheng Yu
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Zhaolan Hu
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yufeng Zhou
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Yulong Wang
- Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Ruping Dai
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jin Li
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| | - Shenglin Huang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Pinglong Xu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, China
| | - Kang Chen
- Perinatology Research Branch, Eunice Kennedy Shriver NICHD, National Institutes of Health, Detroit, MI, USA.,Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, USA.,Jiangsu Province Hospital of TCM, The Affiliated Hospital of Nanjing University of TCM, Nanjing, China
| | - Chen Ding
- State Key Laboratory of Genetic Engineering, Human Phenome Institute, Institutes of Biomedical Sciences, School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Fa-Xing Yu
- Children's Hospital and Institutes of Biomedical Sciences, Key Laboratory of Medical Epigenetics and Metabolism, Fudan University, Shanghai, China
| |
Collapse
|
26
|
Khandagale P, Peroumal D, Manohar K, Acharya N. Human DNA polymerase delta is a pentameric holoenzyme with a dimeric p12 subunit. Life Sci Alliance 2019; 2:2/2/e201900323. [PMID: 30885984 PMCID: PMC6424025 DOI: 10.26508/lsa.201900323] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/04/2019] [Accepted: 03/11/2019] [Indexed: 01/07/2023] Open
Abstract
The subunit p12 of human DNA polymerase delta (hPolδ) can dimerize, facilitating its interaction with PCNA and suggesting that hPolδ exists in a pentameric form in the cell. Human DNA polymerase delta (Polδ), a holoenzyme consisting of p125, p50, p68, and p12 subunits, plays an essential role in DNA replication, repair, and recombination. Herein, using multiple physicochemical and cellular approaches, we found that the p12 protein forms a dimer in solution. In vitro reconstitution and pull down of cellular Polδ by tagged p12 substantiate the pentameric nature of this critical holoenzyme. Furthermore, a consensus proliferating nuclear antigen (PCNA) interaction protein motif at the extreme carboxyl-terminal tail and a homodimerization domain at the amino terminus of the p12 subunit were identified. Mutational analyses of these motifs in p12 suggest that dimerization facilitates p12 binding to the interdomain connecting loop of PCNA. In addition, we observed that oligomerization of the smallest subunit of Polδ is evolutionarily conserved as Cdm1 of Schizosaccharomyces pombe also dimerizes. Thus, we suggest that human Polδ is a pentameric complex with a dimeric p12 subunit, and discuss implications of p12 dimerization in enzyme architecture and PCNA interaction during DNA replication.
Collapse
Affiliation(s)
- Prashant Khandagale
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Doureradjou Peroumal
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Kodavati Manohar
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Narottam Acharya
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| |
Collapse
|
27
|
Chiang HS, Liu HM. The Molecular Basis of Viral Inhibition of IRF- and STAT-Dependent Immune Responses. Front Immunol 2019; 9:3086. [PMID: 30671058 PMCID: PMC6332930 DOI: 10.3389/fimmu.2018.03086] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/13/2018] [Indexed: 01/07/2023] Open
Abstract
The antiviral innate immunity is the first line of host defense against virus infections. In mammalian cells, viral infections initiate the expression of interferons (IFNs) in the host that in turn activate an antiviral defense program to restrict viral replications by induction of IFN stimulated genes (ISGs), which are largely regulated by the IFN-regulatory factor (IRF) family and signal transducer and activator of transcription (STAT) family transcription factors. The mechanisms of action of IRFs and STATs involve several post-translational modifications, complex formation, and nuclear translocation of these transcription factors. However, many viruses, including human immunodeficiency virus (HIV), Zika virus (ZIKV), and herpes simplex virus (HSV), have evolved strategies to evade host defense, including alteration in IRF and STAT post-translational modifications, disturbing the formation and nuclear translocation of the transcription complexes as well as proteolysis/degradation of IRFs and STATs. In this review, we discuss and summarize the molecular mechanisms by which how viral components may target IRFs and STATs to antagonize the establishment of antiviral host defense. The underlying host-viral interactions determine the outcome of viral infection. Gaining mechanistic insight into these processes will be crucial in understanding how viral replication can be more effectively controlled and in developing approaches to improve virus infection outcomes.
Collapse
Affiliation(s)
- Hao-Sen Chiang
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University, Taipei, Taiwan
| | - Helene Minyi Liu
- Graduate Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| |
Collapse
|
28
|
Evidence for Stabilizing Selection Driving Mutational Turnover of Short Motifs in the Eukaryotic Complementary Sex Determiner (Csd) Protein. G3-GENES GENOMES GENETICS 2018; 8:3803-3812. [PMID: 30287489 PMCID: PMC6288827 DOI: 10.1534/g3.118.200527] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Short linear motifs (SLiMs) can play pivotal functional roles in proteins, such as targeting proteins to specific subcellular localizations, modulating the efficiency of translation and tagging proteins for degradation. Until recently we had little knowledge about SLiM evolution. Only a few amino acids in these motifs are functionally important, making them likely to evolve ex nihilo and suggesting that they can play key roles in protein evolution. Several reports now suggest that these motifs can appear and disappear while their function in the protein is preserved, a process sometimes referred to as “turnover”. However, there has been a lack of specific experiments to determine whether independently evolved motifs do indeed have the same function, which would conclusively determine whether the process of turnover actually occurs. In this study, we experimentally detected evidence for such a mutational turnover process for nuclear localization signals (NLS) during the post-duplication divergence of the Complementary sex determiner (Csd) and Feminizer (Fem) proteins in the honeybee (Apis mellifera) lineage. Experiments on the nuclear transport activity of protein segments and those of the most recent common ancestor (MRCA) sequences revealed that three new NLS motifs evolved in the Csd protein during the post-duplication divergence while other NLS motifs were lost that existed before duplication. A screen for essential and newly evolved amino acids revealed that new motifs in the Csd protein evolved by one or two missense mutations coding for lysine. Amino acids that were predating the duplication were also essential in the acquisition of the C1 motif suggesting that the ex nihilo origin was constrained by preexisting amino acids in the physical proximity. Our data support a model in which stabilizing selection maintains the constancy of nuclear transport function but allowed mutational turnover of the encoding NLS motifs.
Collapse
|
29
|
The Methyltransferase-Like Domain of Chikungunya Virus nsP2 Inhibits the Interferon Response by Promoting the Nuclear Export of STAT1. J Virol 2018; 92:JVI.01008-18. [PMID: 29925658 DOI: 10.1128/jvi.01008-18] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 06/14/2018] [Indexed: 12/15/2022] Open
Abstract
Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that has evolved effective mechanisms to counteract the type I interferon (IFN) response. Upon recognition of the virus, cells secrete IFNs, which signal through transmembrane receptors (IFNAR) to phosphorylate STAT proteins (pSTAT). pSTAT dimers are transported into the nucleus by importin-α5 and activate the transcription of IFN-stimulated genes (ISGs), increasing cellular resistance to infection. Subsequently, STAT proteins are shuttled back into the cytoplasm by the exportin CRM1. CHIKV nonstructural protein 2 (nsP2) reduces ISG expression by inhibiting general host cell transcription and by specifically reducing the levels of nuclear pSTAT1 via an unknown mechanism. To systematically examine where nsP2 acts within the JAK/STAT signaling cascade, we used two well-characterized mutants of nsP2, P718S and KR649AA. Both mutations abrogate nsP2's ability to shut off host transcription, but only the KR649AA mutant localizes exclusively to the cytoplasm and no longer specifically inhibits JAK/STAT signaling. These mutant nsP2 proteins did not differentially affect IFNAR expression levels or STAT1 phosphorylation in response to IFNs. Coimmunoprecipitation experiments showed that in the presence of nsP2, STAT1 still effectively bound importin-α5. Chemically blocking CRM1-mediated nuclear export in the presence of nsP2 additionally showed that nuclear translocation of STAT1 is not affected by nsP2. nsP2 putatively has five domains. Redirecting the nsP2 KR649AA mutant or just nsP2's C-terminal methyltransferase-like domain into the nucleus strongly reduced nuclear pSTAT in response to IFN stimulation. This demonstrates that the C-terminal domain of nuclear nsP2 specifically inhibits the IFN response by promoting the nuclear export of STAT1.IMPORTANCE Chikungunya virus is an emerging pathogen associated with large outbreaks on the African, Asian, European, and both American continents. In most patients, infection results in high fever, rash, and incapacitating (chronic) arthralgia. CHIKV effectively inhibits the first line of defense, the innate immune response. As a result, stimulation of the innate immune response with interferons (IFNs) is ineffective as a treatment for CHIKV disease. The IFN response requires an intact downstream signaling cascade called the JAK/STAT signaling pathway, which is effectively inhibited by CHIKV nonstructural protein 2 (nsP2) via an unknown mechanism. The research described here specifies where in the JAK/STAT signaling cascade the IFN response is inhibited and which protein domain of nsP2 is responsible for IFN inhibition. The results illuminate new aspects of antiviral defense and CHIKV counterdefense strategies and will direct the search for novel antiviral compounds.
Collapse
|
30
|
Beck M, Schirmacher P, Singer S. Alterations of the nuclear transport system in hepatocellular carcinoma - New basis for therapeutic strategies. J Hepatol 2017; 67:1051-1061. [PMID: 28673770 DOI: 10.1016/j.jhep.2017.06.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/20/2017] [Accepted: 06/21/2017] [Indexed: 12/20/2022]
Abstract
Hepatocellular carcinoma (HCC) is among the most prevalent human malignancies worldwide with rising incidence in industrialised countries, few therapeutic options and poor prognosis. To expand and improve therapeutic strategies, identification of drug targets involved in several liver cancer-related pathways is crucial. Virtually all signal transduction cascades cross the nuclear envelope and therefore require components of the nuclear transport system (NTS), including nuclear transport receptors (e.g. importins and exportins) and the nuclear pore complex. Accordingly, members of the NTS represent promising targets for therapeutic intervention. Selective inhibitors of nuclear export have already entered clinical trials for various malignancies. Herein, we review the current knowledge regarding alterations of the NTS and their potential for targeted therapy in HCC.
Collapse
Affiliation(s)
- Martin Beck
- European Molecular Biology Laboratory, Heidelberg, Germany
| | | | - Stephan Singer
- European Molecular Biology Laboratory, Heidelberg, Germany; Institute of Pathology, University Hospital Heidelberg, Germany.
| |
Collapse
|
31
|
Nipah and Hendra Virus Nucleoproteins Inhibit Nuclear Accumulation of Signal Transducer and Activator of Transcription 1 (STAT1) and STAT2 by Interfering with Their Complex Formation. J Virol 2017; 91:JVI.01136-17. [PMID: 28835499 DOI: 10.1128/jvi.01136-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/16/2017] [Indexed: 12/25/2022] Open
Abstract
Henipaviruses, such as Nipah (NiV) and Hendra (HeV) viruses, are highly pathogenic zoonotic agents within the Paramyxoviridae family. The phosphoprotein (P) gene products of the paramyxoviruses have been well characterized for their interferon (IFN) antagonist activity and their contribution to viral pathogenicity. In this study, we demonstrated that the nucleoprotein (N) of henipaviruses also prevents the host IFN signaling response. Reporter assays demonstrated that the NiV and HeV N proteins (NiV-N and HeV-N, respectively) dose-dependently suppressed both type I and type II IFN responses and that the inhibitory effect was mediated by their core domains. Additionally, NiV-N prevented the nuclear transport of signal transducer and activator of transcription 1 (STAT1) and STAT2. However, NiV-N did not associate with Impα5, Impβ1, or Ran, which are members of the nuclear transport system for STATs. Although P protein is known as a binding partner of N protein and actively retains N protein in the cytoplasm, the IFN antagonist activity of N protein was not abolished by the coexpression of P protein. This suggests that the IFN inhibition by N protein occurs in the cytoplasm. Furthermore, we demonstrated that the complex formation of STATs was hampered in the N protein-expressing cells. As a result, STAT nuclear accumulation was reduced, causing a subsequent downregulation of interferon-stimulated genes (ISGs) due to low promoter occupancy by STAT complexes. This novel route for preventing host IFN responses by henipavirus N proteins provides new insight into the pathogenesis of these viruses.IMPORTANCE Paramyxoviruses are well known for suppressing interferon (IFN)-mediated innate immunity with their phosphoprotein (P) gene products, and the henipaviruses also possess P, V, W, and C proteins for evading host antiviral responses. There are numerous studies providing evidence for the relationship between viral pathogenicity and antagonistic activities against IFN responses by P gene products. Meanwhile, little attention has been paid to the influence of nucleoprotein (N) on host innate immune responses. In this study, we demonstrated that both the NiV and HeV N proteins have antagonistic activity against the JAK/STAT signaling pathway by preventing the nucleocytoplasmic trafficking of STAT1 and STAT2. This inhibitory effect is due to an impairment of the ability of STATs to form complexes. These results provide new insight into the involvement of N protein in viral pathogenicity via its IFN antagonism.
Collapse
|
32
|
Differential Antagonism of Human Innate Immune Responses by Tick-Borne Phlebovirus Nonstructural Proteins. mSphere 2017; 2:mSphere00234-17. [PMID: 28680969 PMCID: PMC5489658 DOI: 10.1128/msphere.00234-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/05/2017] [Indexed: 12/24/2022] Open
Abstract
In recent years, several newly discovered tick-borne viruses causing a wide spectrum of diseases in humans have been ascribed to the Phlebovirus genus of the Bunyaviridae family. The nonstructural protein (NSs) of bunyaviruses is the main virulence factor and interferon (IFN) antagonist. We studied the molecular mechanisms of IFN antagonism employed by the NSs proteins of human apathogenic Uukuniemi virus (UUKV) and those of Heartland virus (HRTV) and severe fever with thrombocytopenia syndrome virus (SFTSV), both of which cause severe disease. Using reporter assays, we found that UUKV NSs weakly inhibited the activation of the beta interferon (IFN-β) promoter and response elements. UUKV NSs weakly antagonized human IFN-β promoter activation through a novel interaction with mitochondrial antiviral-signaling protein (MAVS), confirmed by coimmunoprecipitation and confocal microscopy studies. HRTV NSs efficiently antagonized both IFN-β promoter activation and type I IFN signaling pathways through interactions with TBK1, preventing its phosphorylation. HRTV NSs exhibited diffused cytoplasmic localization. This is in comparison to the inclusion bodies formed by SFTSV NSs. HRTV NSs also efficiently interacted with STAT2 and impaired IFN-β-induced phosphorylation but did not affect STAT1 or its translocation to the nucleus. Our results suggest that a weak interaction between STAT1 and HRTV or SFTSV NSs may explain their inability to block type II IFN signaling efficiently, thus enabling the activation of proinflammatory responses that lead to severe disease. Our findings offer insights into how pathogenicity may be linked to the capacity of NSs proteins to block the innate immune system and illustrate the plethora of viral immune evasion strategies utilized by emerging phleboviruses. IMPORTANCE Since 2011, there has been a large expansion in the number of emerging tick-borne viruses that have been assigned to the Phlebovirus genus. Heartland virus (HRTV) and SFTS virus (SFTSV) were found to cause severe disease in humans, unlike other documented tick-borne phleboviruses such as Uukuniemi virus (UUKV). Phleboviruses encode nonstructural proteins (NSs) that enable them to counteract the human innate antiviral defenses. We assessed how these proteins interacted with the innate immune system. We found that UUKV NSs engaged with innate immune factors only weakly, at one early step. However, the viruses that cause more severe disease efficiently disabled the antiviral response by targeting multiple components at several stages across the innate immune induction and signaling pathways. Our results suggest a correlation between the efficiency of the virus protein/host interaction and severity of disease.
Collapse
|
33
|
Saini SK, Mangalhara KC, Prakasam G, Bamezai RNK. DNA Methyltransferase1 (DNMT1) Isoform3 methylates mitochondrial genome and modulates its biology. Sci Rep 2017; 7:1525. [PMID: 28484249 PMCID: PMC5431478 DOI: 10.1038/s41598-017-01743-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 04/12/2017] [Indexed: 12/21/2022] Open
Abstract
Here we demonstrate localization of the isoform3 of DNA Methyltransferase1 (DNMT1) enzyme to mitochondria, instead of isoform1 as reported earlier. The fused DNMT1-isoform1, reported earlier to localize in mitochondria, surprisingly showed its exclusive presence inside the nucleus after its ectopic expression; and failed to localize in mitochondria. On the other hand, ectopically expressed DNMT1-isoform3 targeted itself to mitochondria and subsequently methylated CpG regions in the mitochondrial genome. In addition, overexpression of DNMT1-isoform3 affected mitochondrial biology and regulated its function. Under different conditions of oxidative and nutritional stress, this isoform was down-regulated, resulting in hypomethylation of mitochondrial genome. Our study reveals how DNMT1-isoform3, instead of isoform1, is responsible for mtDNA methylation, influencing its biology.
Collapse
Affiliation(s)
- Sunil Kumar Saini
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Kailash Chandra Mangalhara
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Gopinath Prakasam
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - R N K Bamezai
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
| |
Collapse
|
34
|
Li F, Zhang Y, Chen S, Wang M, Jia R, Zhu D, Liu M, Sun K, Yang Q, Wu Y, Chen X, Cheng A. Identification of the Nuclear Localization Signal Region of Duck Enteritis Virus UL14 and Its Interaction with VP16. Intervirology 2017; 59:187-196. [PMID: 28178699 DOI: 10.1159/000452711] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/19/2016] [Indexed: 12/19/2022] Open
Abstract
OBJECT Duck enteritis virus (DEV) is a member of the Alphaherpesvirinae viruses. VP16 and pUL14 are both predicted to be tegument proteins of DEV. METHODS An indirect immunofluorescence assay (IFA) was performed for preliminary analysis of the colocalization of pUL14 and VP16, which detected their subcellular localization in duck embryo fibroblasts (DEFs) during virus replication. The coexpression of pUL14 and VP16 was detected in transfected DEFs. A bimolecular fluorescence complementation (BiFC) assay was used to confirm a direct interaction between pUL14 and VP16. To better characterize the nuclear localization domain of pUL14, we designed a series of deletion mutants and transfected them with VP16. RESULTS Our IFA findings indicated that pUL14 binds to VP16 in the cytoplasm and that pUL14 leads VP16 import into the nucleus during DEV replication. The BiFC assay revealed the presence of pUL14 and VP16 complexes. Furthermore, 1-98 amino acid (aa) at the N-terminus of pUL14 played a role in the nuclear localization signal (NLS) region and promoted translocation of VP16 into the nucleus to complete the virus life cycle. CONCLUSIONS Our findings indicated that pUL14 could transport VP16 into the nucleus and that the N-terminal 1-98 aa may contain the NLS domain of pUL14.
Collapse
Affiliation(s)
- FangJie Li
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, PR China
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Ho J, Pelzel C, Begitt A, Mee M, Elsheikha HM, Scott DJ, Vinkemeier U. STAT2 Is a Pervasive Cytokine Regulator due to Its Inhibition of STAT1 in Multiple Signaling Pathways. PLoS Biol 2016; 14:e2000117. [PMID: 27780205 PMCID: PMC5079630 DOI: 10.1371/journal.pbio.2000117] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/07/2016] [Indexed: 01/17/2023] Open
Abstract
STAT2 is the quintessential transcription factor for type 1 interferons (IFNs), where it functions as a heterodimer with STAT1. However, the human and murine STAT2-deficient phenotypes suggest important additional and currently unidentified type 1 IFN-independent activities. Here, we show that STAT2 constitutively bound to STAT1, but not STAT3, via a conserved interface. While this interaction was irrelevant for type 1 interferon signaling and STAT1 activation, it precluded the nuclear translocation specifically of STAT1 in response to IFN-γ, interleukin-6 (IL-6), and IL-27. This is explained by the dimerization between activated STAT1 and unphosphorylated STAT2, whereby the semiphosphorylated dimers adopted a conformation incapable of importin-α binding. This, in turn, substantially attenuated cardinal IFN-γ responses, including MHC expression, senescence, and antiparasitic immunity, and shifted the transcriptional output of IL-27 from STAT1 to STAT3. Our results uncover STAT2 as a pervasive cytokine regulator due to its inhibition of STAT1 in multiple signaling pathways and provide an understanding of the type 1 interferon-independent activities of this protein.
Collapse
Affiliation(s)
- Johnathan Ho
- School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Christin Pelzel
- School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Andreas Begitt
- School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Maureen Mee
- School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Hany M. Elsheikha
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, United Kingdom
| | - David J. Scott
- ISIS Spallation Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, United Kingdom
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, United Kingdom
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Uwe Vinkemeier
- School of Life Sciences, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
- * E-mail:
| |
Collapse
|
36
|
Yao K, Wu Y, Chen Q, Zhang Z, Chen X, Zhang Y. The Arginine/Lysine-Rich Element within the DNA-Binding Domain Is Essential for Nuclear Localization and Function of the Intracellular Pathogen Resistance 1. PLoS One 2016; 11:e0162832. [PMID: 27622275 PMCID: PMC5021326 DOI: 10.1371/journal.pone.0162832] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/29/2016] [Indexed: 12/22/2022] Open
Abstract
The mouse intracellular pathogen resistance 1 (Ipr1) gene plays important roles in mediating host immunity and previous work showed that it enhances macrophage apoptosis upon mycobacterium infection. However, to date, little is known about the regulation pattern of Ipr1 action. Recent studies have investigated the protein-coding genes and microRNAs regulated by Ipr1 in mouse macrophages, but the structure and the functional motif of the Ipr1 protein have yet to be explored. In this study, we analyzed the domains and functional motif of the Ipr1 protein. The resulting data reveal that Ipr1 protein forms a homodimer and that the Sp100-like domain mediates the targeting of Ipr1 protein to nuclear dots (NDs). Moreover, we found that an Ipr1 mutant lacking the classic nuclear localization signal (cNLS) also translocated into the nuclei, suggesting that the cNLS is not the only factor that directs Ipr1 nuclear localization. Additionally, mechanistic studies revealed that an arginine/lysine-rich element within the DNA-binding domain (SAND domain) is critical for Ipr1 binding to the importin protein receptor NPI-1, demonstrating that this element plays an essential role in mediating the nuclear localization of Ipr1 protein. Furthermore, our results show that this arginine/lysine-rich element contributes to the transcriptional regulation and apoptotic activity of Ipr1. These findings highlight the structural foundations of Ipr1 action and provide new insights into the mechanism of Ipr1-mediated resistance to mycobacterium.
Collapse
Affiliation(s)
- Kezhen Yao
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Yongyan Wu
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Qi Chen
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Zihan Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Xin Chen
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Yong Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Animal Biotechnology, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
- * E-mail:
| |
Collapse
|
37
|
Ehrlichia chaffeensis TRP32 is a Nucleomodulin that Directly Regulates Expression of Host Genes Governing Differentiation and Proliferation. Infect Immun 2016; 84:3182-3194. [PMID: 27572329 DOI: 10.1128/iai.00657-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ehrlichia chaffeensis is an obligately intracellular bacterium that reprograms the mononuclear phagocyte through diverse effector-host interactions to modulate numerous host cell processes, including transcription. In a previous study, we reported that E. chaffeensis TRP32, a type 1 secreted effector, interacts with multiple host nucleus-associated proteins and also auto-activates reporter gene expression in yeast. In this study, we demonstrate that TRP32 is a nucleomodulin that binds host DNA and alters host gene transcription. TRP32 enters the host cell nucleus via a noncanonical translocation mechanism that involves phosphorylation of Y179 located in a C-terminal tri-tyrosine motif. Both genistein and mutation of Y179 inhibited TRP32 nuclear entry. An electromobility shift assay (EMSA) demonstrated TRP32 host DNA binding via its tandem repeat domain. TRP32 DNA binding and motif preference were further confirmed by supershift assays, as well as competition and mutant probe analyses. Using ChIP-Seq, we determined that TRP32 binds a G-rich motif primarily within ±500 bp of the gene transcription start site. An ontology analysis identified genes involved in processes such as immune cell differentiation, chromatin remodeling, and RNA transcription and processing, as primary TRP32 targets. TRP32 bound genes (n=1223) were distributed on all chromosomes and included several global regulators of proliferation and inflammation such as FOS and JUN, AKT3 and NRAS, and non-coding RNA genes, miRNA 21 and miRNA 142. TRP32 target genes were differentially regulated during infection, the majority of which were repressed, and direct repression/activation of these genes by TRP32 was confirmed in vitro with a cellular luciferase reporter assay.
Collapse
|
38
|
Ren Y, Zhao P, Liu J, Yuan Y, Cheng Q, Zuo Y, Qian L, Liu C, Guo T, Zhang L, Wang X, Qian G, Li L, Ge J, Dai J, Xiong S, Zheng H. Deubiquitinase USP2a Sustains Interferons Antiviral Activity by Restricting Ubiquitination of Activated STAT1 in the Nucleus. PLoS Pathog 2016; 12:e1005764. [PMID: 27434509 PMCID: PMC4951015 DOI: 10.1371/journal.ppat.1005764] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 06/22/2016] [Indexed: 11/29/2022] Open
Abstract
STAT1 is a critical transcription factor for regulating host antiviral defenses. STAT1 activation is largely dependent on phosphorylation at tyrosine 701 site of STAT1 (pY701-STAT1). Understanding how pY701-STAT1 is regulated by intracellular signaling remains a major challenge. Here we find that pY701-STAT1 is the major form of ubiquitinated-STAT1 induced by interferons (IFNs). While total STAT1 remains relatively stable during the early stages of IFNs signaling, pY701-STAT1 can be rapidly downregulated by the ubiquitin-proteasome system. Moreover, ubiquitinated pY701-STAT1 is located predominantly in the nucleus, and inhibiting nuclear import of pY701-STAT1 significantly blocks ubiquitination and downregulation of pY701-STAT1. Furthermore, we reveal that the deubiquitinase USP2a translocates into the nucleus and binds to pY701-STAT1, and inhibits K48-linked ubiquitination and degradation of pY701-STAT1. Importantly, USP2a sustains IFNs-induced pY701-STAT1 levels, and enhances all three classes of IFNs- mediated signaling and antiviral activity. To our knowledge, this is the first identified deubiquitinase that targets activated pY701-STAT1. These findings uncover a positive mechanism by which IFNs execute efficient antiviral signaling and function, and may provide potential targets for improving IFNs-based antiviral therapy. Phosphorylated STAT1 at tyrosine 701 site (pY701-STAT1) is critical for regulating many cellular functions including antiviral immunity. Maintaining sufficient pY701-STAT1 levels in the nucleus is essential to sustain efficient interferons (IFNs) signaling and antiviral functions. Therefore, it is important to clarify how pY701-STAT1 levels are positively regulated in the nucleus. Here, we demonstrated for the first time that IFNs-induced pY701-STAT1 largely raised STAT1 ubiquitination, and ubiquitinated-pY701-STAT1 is located predominantly in the nucleus and regulated by proteasome-dependent degradation. In IFNs signaling, the deubiquitinase USP2a translocates into the nucleus and binds to pY701-STAT1. USP2a positively regulates pY701-STAT1 levels through inhibiting its K48-linked ubiquitination and degradation. Importantly, USP2a sustains all three classes of IFNs-mediated signaling and antiviral function. Our studies uncover an important positive mechanism in the nucleus by which IFNs can execute efficient antiviral signaling and functions.
Collapse
Affiliation(s)
- Ying Ren
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Peng Zhao
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Jin Liu
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Yukang Yuan
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Qiao Cheng
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Yibo Zuo
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Liping Qian
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Chang Liu
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Tingting Guo
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Liting Zhang
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Xiaofang Wang
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Guanghui Qian
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Lemin Li
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Jun Ge
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Jianfeng Dai
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
| | - Sidong Xiong
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
- Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Jiangsu, China
- * E-mail: (SX); (HZ)
| | - Hui Zheng
- Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China
- Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Jiangsu, China
- * E-mail: (SX); (HZ)
| |
Collapse
|
39
|
Metrick CM, Heldwein EE. Novel Structure and Unexpected RNA-Binding Ability of the C-Terminal Domain of Herpes Simplex Virus 1 Tegument Protein UL21. J Virol 2016; 90:5759-69. [PMID: 27053559 PMCID: PMC4886797 DOI: 10.1128/jvi.00475-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 04/01/2016] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED Proteins forming the tegument layers of herpesviral virions mediate many essential processes in the viral replication cycle, yet few have been characterized in detail. UL21 is one such multifunctional tegument protein and is conserved among alphaherpesviruses. While UL21 has been implicated in many processes in viral replication, ranging from nuclear egress to virion morphogenesis to cell-cell spread, its precise roles remain unclear. Here we report the 2.7-Å crystal structure of the C-terminal domain of herpes simplex virus 1 (HSV-1) UL21 (UL21C), which has a unique α-helical fold resembling a dragonfly. Analysis of evolutionary conservation patterns and surface electrostatics pinpointed four regions of potential functional importance on the surface of UL21C to be pursued by mutagenesis. In combination with the previously determined structure of the N-terminal domain of UL21, the structure of UL21C provides a 3-dimensional framework for targeted exploration of the multiple roles of UL21 in the replication and pathogenesis of alphaherpesviruses. Additionally, we describe an unanticipated ability of UL21 to bind RNA, which may hint at a yet unexplored function. IMPORTANCE Due to the limited genomic coding capacity of viruses, viral proteins are often multifunctional, which makes them attractive antiviral targets. Such multifunctionality, however, complicates their study, which often involves constructing and characterizing null mutant viruses. Systematic exploration of these multifunctional proteins requires detailed road maps in the form of 3-dimensional structures. In this work, we determined the crystal structure of the C-terminal domain of UL21, a multifunctional tegument protein that is conserved among alphaherpesviruses. Structural analysis pinpointed surface areas of potential functional importance that provide a starting point for mutagenesis. In addition, the unexpected RNA-binding ability of UL21 may expand its functional repertoire. The structure of UL21C and the observation of its RNA-binding ability are the latest additions to the navigational chart that can guide the exploration of the multiple functions of UL21.
Collapse
Affiliation(s)
- Claire M Metrick
- Department of Molecular Biology and Microbiology and Graduate Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USAUniversity of California, Irvine
| | - Ekaterina E Heldwein
- Department of Molecular Biology and Microbiology and Graduate Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USAUniversity of California, Irvine
| |
Collapse
|
40
|
The unique role of STAT2 in constitutive and IFN-induced transcription and antiviral responses. Cytokine Growth Factor Rev 2016; 29:71-81. [PMID: 27053489 DOI: 10.1016/j.cytogfr.2016.02.010] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/27/2016] [Indexed: 11/20/2022]
Abstract
In the canonical pathway of IFN-I-mediated signaling, phosphorylation of STAT1 and STAT2 leads to heterodimerization and interaction with IRF9. This complex, also known as IFN-stimulated gene factor 3 (ISGF3), then translocates into the nucleus and binds the IFN-I-stimulated response element (ISRE) leading to the activation of transcription of over 300 interferon stimulated genes (ISGs). In addition, STAT1 homodimers [known as γ-activated factor (GAF)] are formed and translocate to the nucleus, where they target genes containing the γ-activated sequence (GAS). The primary function of ISGF3 is to mediate a rapid and robust IFN-I activated response by regulating transient transcription of antiviral ISGs. This requires the quick assembly of ISGF3 from its pre-existing components STAT1, STAT2 and IRF9 and transport to the nucleus to bind ISRE-containing ISGs. The exact events that take place in formation, nuclear translocation and DNA-binding of active ISGF3 are still not clear. Over the years many studies have provided evidence for the existence of a multitude of alternative STAT2-containing (ISRE or GAS-binding) complexes involved in IFN-I signaling, emphasizing the importance of STAT2 in the regulation of specific IFN-I-induced transcriptional programs, independent of its involvement in the classical ISGF3 complex. This review describes the unique role of STAT2 in differential complex formation of unphosphorylated and phosphorylated ISGF3 components that direct constitutive and IFN-I-stimulated transcriptional responses. In addition, we highlight the existence of a STAT1-independent IFN-I signaling pathway, where STAT2/IRF9 can potentially substitute for the role of ISGF3 and offer a back-up response against viral infection.
Collapse
|
41
|
van der Watt PJ, Chi A, Stelma T, Stowell C, Strydom E, Carden S, Angus L, Hadley K, Lang D, Wei W, Birrer MJ, Trent JO, Leaner VD. Targeting the Nuclear Import Receptor Kpnβ1 as an Anticancer Therapeutic. Mol Cancer Ther 2016; 15:560-73. [PMID: 26832790 DOI: 10.1158/1535-7163.mct-15-0052] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 01/15/2016] [Indexed: 11/16/2022]
Abstract
Karyopherin beta 1 (Kpnβ1) is a nuclear transport receptor that imports cargoes into the nucleus. Recently, elevated Kpnβ1 expression was found in certain cancers and Kpnβ1 silencing with siRNA was shown to induce cancer cell death. This study aimed to identify novel small molecule inhibitors of Kpnβ1, and determine their anticancer activity. An in silico screen identified molecules that potentially bind Kpnβ1 and Inhibitor of Nuclear Import-43, INI-43 (3-(1H-benzimidazol-2-yl)-1-(3-dimethylaminopropyl)pyrrolo[5,4-b]quinoxalin-2-amine) was investigated further as it interfered with the nuclear localization of Kpnβ1 and known Kpnβ1 cargoes NFAT, NFκB, AP-1, and NFY and inhibited the proliferation of cancer cells of different tissue origins. Minimum effect on the proliferation of noncancer cells was observed at the concentration of INI-43 that showed a significant cytotoxic effect on various cervical and esophageal cancer cell lines. A rescue experiment confirmed that INI-43 exerted its cell killing effects, in part, by targeting Kpnβ1. INI-43 treatment elicited a G2-M cell-cycle arrest in cancer cells and induced the intrinsic apoptotic pathway. Intraperitoneal administration of INI-43 significantly inhibited the growth of subcutaneously xenografted esophageal and cervical tumor cells. We propose that Kpnβ1 inhibitors could have therapeutic potential for the treatment of cancer. Mol Cancer Ther; 15(4); 560-73. ©2016 AACR.
Collapse
Affiliation(s)
- Pauline J van der Watt
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Alicia Chi
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Tamara Stelma
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Catherine Stowell
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Erin Strydom
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Sarah Carden
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Liselotte Angus
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Kate Hadley
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Dirk Lang
- Confocal and Light Microscope Imaging Facility, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Wei Wei
- Center for Cancer Research, The Gillette Center for Gynecologic Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Michael J Birrer
- Center for Cancer Research, The Gillette Center for Gynecologic Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - John O Trent
- Department of Medicine, J.G. Brown Cancer Center, University of Louisville, Louisville, Kentucky
| | - Virna D Leaner
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, SAMRC/UCT Gynaecological Cancer Research Centre, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
| |
Collapse
|
42
|
Christie M, Chang CW, Róna G, Smith KM, Stewart AG, Takeda AAS, Fontes MRM, Stewart M, Vértessy BG, Forwood JK, Kobe B. Structural Biology and Regulation of Protein Import into the Nucleus. J Mol Biol 2015; 428:2060-90. [PMID: 26523678 DOI: 10.1016/j.jmb.2015.10.023] [Citation(s) in RCA: 176] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/16/2015] [Accepted: 10/24/2015] [Indexed: 11/28/2022]
Abstract
Proteins are translated in the cytoplasm, but many need to access the nucleus to perform their functions. Understanding how these nuclear proteins are transported through the nuclear envelope and how the import processes are regulated is therefore an important aspect of understanding cell function. Structural biology has played a key role in understanding the molecular events during the transport processes and their regulation, including the recognition of nuclear targeting signals by the corresponding receptors. Here, we review the structural basis of the principal nuclear import pathways and the molecular basis of their regulation. The pathways involve transport factors that are members of the β-karyopherin family, which can bind cargo directly (e.g., importin-β, transportin-1, transportin-3, importin-13) or through adaptor proteins (e.g., importin-α, snurportin-1, symportin-1), as well as unrelated transport factors such as Hikeshi, involved in the transport of heat-shock proteins, and NTF2, involved in the transport of RanGDP. Solenoid proteins feature prominently in these pathways. Nuclear transport factors recognize nuclear targeting signals on the cargo proteins, including the classical nuclear localization signals, recognized by the adaptor importin-α, and the PY nuclear localization signals, recognized by transportin-1. Post-translational modifications, particularly phosphorylation, constitute key regulatory mechanisms operating in these pathways.
Collapse
Affiliation(s)
- Mary Christie
- The Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, University of New South Wales Faculty of Medicine, Darlinghurst, NSW 2010, Australia
| | - Chiung-Wen Chang
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Gergely Róna
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest H-1117, Hungary; Department of Applied Biotechnology and Food Sciences, Budapest University of Technology and Economics, Budapest H-1111, Hungary
| | - Kate M Smith
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia
| | - Alastair G Stewart
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Agnes A S Takeda
- Department of Physics and Biophysics, Institute of Biosciences, Universidade Estadual Paulista, Botucatu, São Paulo 18618-000, Brazil
| | - Marcos R M Fontes
- Department of Physics and Biophysics, Institute of Biosciences, Universidade Estadual Paulista, Botucatu, São Paulo 18618-000, Brazil
| | - Murray Stewart
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom
| | - Beáta G Vértessy
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest H-1117, Hungary; Department of Applied Biotechnology and Food Sciences, Budapest University of Technology and Economics, Budapest H-1111, Hungary
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia.
| |
Collapse
|
43
|
The two interfaces of the STAT1 N-terminus exhibit opposite functions in IFNγ-regulated gene expression. Mol Immunol 2015; 67:596-606. [PMID: 26275341 DOI: 10.1016/j.molimm.2015.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/13/2015] [Accepted: 07/13/2015] [Indexed: 01/07/2023]
Abstract
Defective cooperative DNA binding of STAT1 (signal transducer and activator of transcription 1) transcription factor has impact on interferon-γ(IFNγ)-regulated transcriptional responses. In this study, we generated N-terminal gain-of-function mutants of this protein which exhibited hyperactive cooperativity and assessed their functional consequences on gene expression. Our data show that four negatively charged, surface-exposed amino acid residues in the N-terminal domain dimer are engaged in the disassembly of tyrosine-phosphorylated tetrameric complexes on DNA and prevent the occurrence of higher-order STAT1 oligomers on low-affinity DNA binding sites. Owing to their improved tetramer stability, the N-terminal mutants showed relaxed sequence requirements for the binding to DNA as compared to the wild-type protein. Similarly to a STAT1 mutant with impaired tetramerization, the N-terminal gain-of-function mutants showed elevated tyrosine-phosphorylation levels and prolonged nuclear accumulation upon stimulation of cells with IFNγ. However, in contrast to the global impairment of IFNγ signalling in tetramerization-deficient mutants, the transcriptional consequences of the N-terminal gain-of-function mutants are rather distinct and affect gene expression locally in a promoter-specific manner. Thus, we conclude that the STAT1 N-domain acts as a double-edged sword: while one interface is crucial for the formation of tetrameric complexes on IFNγ-regulated promoters, the opposite interface harbours an inhibitory mechanism that limits the accumulation of higher-order oligomers simply by disrupting cooperative DNA binding.
Collapse
|
44
|
Abstract
The human genome encodes seven isoforms of importin α which are grouped into three subfamilies known as α1, α2 and α3. All isoforms share a fundamentally conserved architecture that consists of an N-terminal, autoinhibitory, importin-β-binding (IBB) domain and a C-terminal Arm (Armadillo)-core that associates with nuclear localization signal (NLS) cargoes. Despite striking similarity in amino acid sequence and 3D structure, importin-α isoforms display remarkable substrate specificity in vivo. In the present review, we look at key differences among importin-α isoforms and provide a comprehensive inventory of known viral and cellular cargoes that have been shown to associate preferentially with specific isoforms. We illustrate how the diversification of the adaptor importin α into seven isoforms expands the dynamic range and regulatory control of nucleocytoplasmic transport, offering unexpected opportunities for pharmacological intervention. The emerging view of importin α is that of a key signalling molecule, with isoforms that confer preferential nuclear entry and spatiotemporal specificity on viral and cellular cargoes directly linked to human diseases.
Collapse
|
45
|
Pandit V, Watson A, Ren L, Mixon A, Kotha SP. Multilayered Nanoparticles for Gene Delivery Used to Reprogram Human Foreskin Fibroblasts to Neurospheres. Tissue Eng Part C Methods 2015; 21:786-94. [PMID: 25687130 DOI: 10.1089/ten.tec.2014.0482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Polycationic nanocomplexes are a robust means for achieving nucleic acid condensation and efficient intracellular gene deliveries. To enhance delivery, a multilayered nanoparticle consisting of a core of electrostatically bound elements was used. These included a histone-mimetic peptides, poly-l-arginine and poly-d-glutamic acid was coated with silicate before surface functionalization with poly-l-arginine. Transfection efficiencies and duration of expression were similar when using green fluorescent protein (GFP) plasmid DNA (pDNA) or GFP mRNA. These nanoparticles demonstrated significantly higher (>100%) and significantly longer (15 vs. 4 days) transfection efficiencies in comparison to a commercial transfection agent (Lipofectamine 2000). Reprogramming of human foreskin fibroblasts using mRNA to the Sox2 transcription factor resulted in three-fold higher neurosphere formation in comparison to the commercial reagent. These results demonstrate the potential of these nanoparticles as ideal vectors for gene delivery.
Collapse
Affiliation(s)
- Vaibhav Pandit
- 1 Department of Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York
| | | | - Liyun Ren
- 3 Department of Material Science and Engineering, Rensselaer Polytechnic Institute , Troy, New York
| | - Amanda Mixon
- 1 Department of Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York
| | - Shiva P Kotha
- 1 Department of Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York
| |
Collapse
|
46
|
Riebeling T, Staab J, Herrmann-Lingen C, Meyer T. DNA binding reduces the dissociation rate of STAT1 dimers and impairs the interdimeric exchange of protomers. BMC BIOCHEMISTRY 2014; 15:28. [PMID: 25526807 PMCID: PMC4284922 DOI: 10.1186/s12858-014-0028-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 12/11/2014] [Indexed: 01/14/2023]
Abstract
BACKGROUND A shift between two dimer conformations has been proposed for the transcription factor STAT1 (signal transducer and activator of transcription 1) which links DNA binding of the parallel dimer to tyrosine dephosphorylation of the antiparallel dimer as two consecutive and important steps in interferon- γ (IFNγ)-mediated signalling. However, neither the kinetics nor the molecular mechanisms involved in this conformational transition have been determined so far. RESULTS Our results demonstrated that the dissociation of dimers into monomers and their subsequent re-association into newly formed tyrosine-phosphorylated dimers is a relatively slow process as compared to the fast release from high-affinity DNA-binding sites, termed GAS (gamma-activated sequence). In addition, we noted an inhibitory effect of GAS binding on the exchange rate of protomers, indicating that DNA binding substantially impedes the recombination of dimeric STAT1. Furthermore, we found that reciprocal aminoterminal interactions between two STAT1 molecules are not required for the interchange of protomers, as an oligomerization-deficient point mutant displayed similar interdimeric exchange kinetics as the wild-type molecule. CONCLUSIONS Our results demonstrate that DNA binding impairs the oscillation rate between STAT1 conformers. Furthermore, these data suggest that the rapid release from high-affinity GAS sites is not a rate-limiting step in IFNγ-mediated signal transduction. Further investigations are needed to decipher the physiological significance of the observed dissociation/re-association process of STAT1 dimers.
Collapse
Affiliation(s)
- Theresa Riebeling
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Waldweg 33, 37073, Göttingen, Germany.
| | - Julia Staab
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Waldweg 33, 37073, Göttingen, Germany.
| | - Christoph Herrmann-Lingen
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Waldweg 33, 37073, Göttingen, Germany.
| | - Thomas Meyer
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Waldweg 33, 37073, Göttingen, Germany.
| |
Collapse
|
47
|
Mycoplasma gallisepticum MGA_0676 is a membrane-associated cytotoxic nuclease with a staphylococcal nuclease region essential for nuclear translocation and apoptosis induction in chicken cells. Appl Microbiol Biotechnol 2014; 99:1859-71. [DOI: 10.1007/s00253-014-6185-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/20/2014] [Accepted: 10/21/2014] [Indexed: 01/24/2023]
|
48
|
Wunderlich CM, Hövelmeyer N, Wunderlich FT. Mechanisms of chronic JAK-STAT3-SOCS3 signaling in obesity. JAKSTAT 2014; 2:e23878. [PMID: 24058813 PMCID: PMC3710326 DOI: 10.4161/jkst.23878] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/03/2013] [Accepted: 02/04/2013] [Indexed: 02/01/2023] Open
Abstract
Janus kinase (JAK)-signal transducers and activators of transcription (STAT) signaling pathways are critical for the maintenance of homeostatic and developmental processes; however, deregulation and chronic activation of JAK-STAT3 results in numerous diseases. Among others, obesity is currently being intensively studied. In obesity, chronic JAK-STAT3 is activated by the CNS by increased circulating leptin levels leading to the development of leptin resistance, whereas in the peripheral organs chronic IL-6-induced JAK-STAT3 impairs insulin action. We report the consequences of chronic JAK-STAT3 induced signaling as present under obese conditions in the main metabolic organs.
Collapse
Affiliation(s)
- Claudia M Wunderlich
- Max Planck Institute for Neurological Research; Institute for Genetics; University of Cologne and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC); Cologne, Germany
| | | | | |
Collapse
|
49
|
Hüntelmann B, Staab J, Herrmann-Lingen C, Meyer T. A conserved motif in the linker domain of STAT1 transcription factor is required for both recognition and release from high-affinity DNA-binding sites. PLoS One 2014; 9:e97633. [PMID: 24847715 PMCID: PMC4029728 DOI: 10.1371/journal.pone.0097633] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/22/2014] [Indexed: 12/24/2022] Open
Abstract
Binding to specific palindromic sequences termed gamma-activated sites (GAS) is a hallmark of gene activation by members of the STAT (signal transducer and activator of transcription) family of cytokine-inducible transcription factors. However, the precise molecular mechanisms involved in the signal-dependent finding of target genes by STAT dimers have not yet been very well studied. In this study, we have characterized a sequence motif in the STAT1 linker domain which is highly conserved among the seven human STAT proteins and includes surface-exposed residues in close proximity to the bound DNA. Using site-directed mutagenesis, we have demonstrated that a lysine residue in position 567 of the full-length molecule is required for GAS recognition. The substitution of alanine for this residue completely abolished both binding to high-affinity GAS elements and transcriptional activation of endogenous target genes in cells stimulated with interferon-γ (IFNγ), while the time course of transient nuclear accumulation and tyrosine phosphorylation were virtually unchanged. In contrast, two glutamic acid residues (E559 and E563) on each monomer are important for the dissociation of dimeric STAT1 from DNA and, when mutated to alanine, result in elevated levels of tyrosine-phosphorylated STAT1 as well as prolonged IFNγ-stimulated nuclear accumulation. In conclusion, our data indicate that the kinetics of signal-dependent GAS binding is determined by an array of glutamic acid residues located at the interior surface of the STAT1 dimer. These negatively charged residues appear to align the long axis of the STAT1 dimer in a position perpendicular to the DNA, thereby facilitating the interaction between lysine 567 and the phosphodiester backbone of a bound GAS element, which is a prerequisite for transient gene induction.
Collapse
Affiliation(s)
- Bettina Hüntelmann
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Julia Staab
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Christoph Herrmann-Lingen
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Thomas Meyer
- Klinik für Psychosomatische Medizin und Psychotherapie, Georg-August-Universität Göttingen, Göttingen, Germany
- * E-mail:
| |
Collapse
|
50
|
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.
Collapse
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.
| |
Collapse
|