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Giotis ES, Laidlaw SM, Bidgood SR, Albrecht D, Burden JJ, Robey RC, Mercer J, Skinner MA. Modulation of Early Host Innate Immune Response by an Avipox Vaccine Virus' Lateral Body Protein. Biomedicines 2020; 8:E634. [PMID: 33352813 PMCID: PMC7766033 DOI: 10.3390/biomedicines8120634] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/14/2022] Open
Abstract
The avian pathogen fowlpox virus (FWPV) has been successfully used as a vaccine vector in poultry and humans, but relatively little is known about its ability to modulate host antiviral immune responses in these hosts, which are replication-permissive and nonpermissive, respectively. FWPV is highly resistant to avian type I interferon (IFN) and able to completely block the host IFN-response. Microarray screening of host IFN-regulated gene expression in cells infected with 59 different, nonessential FWPV gene knockout mutants revealed that FPV184 confers immunomodulatory capacity. We report that the FPV184-knockout virus (FWPVΔ184) induces the cellular IFN response as early as 2 h postinfection. The wild-type, uninduced phenotype can be rescued by transient expression of FPV184 in FWPVΔ184-infected cells. Ectopic expression of FPV184 inhibited polyI:C activation of the chicken IFN-β promoter and IFN-α activation of the chicken Mx1 promoter. Confocal and correlative super-resolution light and electron microscopy demonstrated that FPV184 has a functional nuclear localisation signal domain and is packaged in the lateral bodies of the virions. Taken together, these results provide a paradigm for a late poxvirus structural protein packaged in the lateral bodies, capable of suppressing IFN induction early during the next round of infection.
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Affiliation(s)
- Efstathios S. Giotis
- Section of Virology, School of Medicine, St Mary’s Campus, Imperial College, London W2 1PG, UK; (S.M.L.); (R.C.R.); (M.A.S.)
- School of Life Sciences, University of Essex, Colchester C04 3SQ, UK
| | - Stephen M. Laidlaw
- Section of Virology, School of Medicine, St Mary’s Campus, Imperial College, London W2 1PG, UK; (S.M.L.); (R.C.R.); (M.A.S.)
| | - Susanna R. Bidgood
- Medical Research Council-Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK; (S.R.B.); (D.A.); (J.J.B.); (J.M.)
| | - David Albrecht
- Medical Research Council-Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK; (S.R.B.); (D.A.); (J.J.B.); (J.M.)
| | - Jemima J. Burden
- Medical Research Council-Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK; (S.R.B.); (D.A.); (J.J.B.); (J.M.)
| | - Rebecca C. Robey
- Section of Virology, School of Medicine, St Mary’s Campus, Imperial College, London W2 1PG, UK; (S.M.L.); (R.C.R.); (M.A.S.)
| | - Jason Mercer
- Medical Research Council-Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK; (S.R.B.); (D.A.); (J.J.B.); (J.M.)
| | - Michael A. Skinner
- Section of Virology, School of Medicine, St Mary’s Campus, Imperial College, London W2 1PG, UK; (S.M.L.); (R.C.R.); (M.A.S.)
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2
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The Yersinia virulence effector YopM binds caspase-1 to arrest inflammasome assembly and processing. Cell Host Microbe 2013; 12:799-805. [PMID: 23245324 DOI: 10.1016/j.chom.2012.10.020] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 08/16/2012] [Accepted: 10/19/2012] [Indexed: 12/18/2022]
Abstract
Inflammasome assembly activates caspase-1 and initiates the inflammatory cell death program pyroptosis, which is protective against numerous pathogens. Consequently, several pathogens, including the plague causing bacterium Yersinia pestis, avoid activating this pathway to enhance their virulence. However, bacterial molecules that directly modulate the inflammasome have yet to be identified. Examining the contribution of Yersinia type III secretion effectors to caspase-1 activation, we identified the leucine-rich repeat effector YopM as a potent antagonist of both caspase-1 activity and activation. YopM directly binds caspase-1, which both inhibits caspase-1 activity and sequesters it to block formation of the mature inflammasome. Caspase-1 activation antagonizes Yersinia survival in vivo, and consequently YopM inhibition of caspase-1 is required for Yersinia pathogenesis. Thus, a bacterium obstructs pyroptosis utilizing a direct mechanism of caspase-1 inhibition that is distinct from known viral or host inhibitors.
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Garg AD, Krysko DV, Verfaillie T, Kaczmarek A, Ferreira GB, Marysael T, Rubio N, Firczuk M, Mathieu C, Roebroek AJM, Annaert W, Golab J, de Witte P, Vandenabeele P, Agostinis P. A novel pathway combining calreticulin exposure and ATP secretion in immunogenic cancer cell death. EMBO J 2012; 31:1062-79. [PMID: 22252128 PMCID: PMC3298003 DOI: 10.1038/emboj.2011.497] [Citation(s) in RCA: 590] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 12/21/2011] [Indexed: 12/19/2022] Open
Abstract
Surface-exposed calreticulin (ecto-CRT) and secreted ATP are crucial damage-associated molecular patterns (DAMPs) for immunogenic apoptosis. Inducers of immunogenic apoptosis rely on an endoplasmic reticulum (ER)-based (reactive oxygen species (ROS)-regulated) pathway for ecto-CRT induction, but the ATP secretion pathway is unknown. We found that after photodynamic therapy (PDT), which generates ROS-mediated ER stress, dying cancer cells undergo immunogenic apoptosis characterized by phenotypic maturation (CD80(high), CD83(high), CD86(high), MHC-II(high)) and functional stimulation (NO(high), IL-10(absent), IL-1β(high)) of dendritic cells as well as induction of a protective antitumour immune response. Intriguingly, early after PDT the cancer cells displayed ecto-CRT and secreted ATP before exhibiting biochemical signatures of apoptosis, through overlapping PERK-orchestrated pathways that require a functional secretory pathway and phosphoinositide 3-kinase (PI3K)-mediated plasma membrane/extracellular trafficking. Interestingly, eIF2α phosphorylation and caspase-8 signalling are dispensable for this ecto-CRT exposure. We also identified LRP1/CD91 as the surface docking site for ecto-CRT and found that depletion of PERK, PI3K p110α and LRP1 but not caspase-8 reduced the immunogenicity of the cancer cells. These results unravel a novel PERK-dependent subroutine for the early and simultaneous emission of two critical DAMPs following ROS-mediated ER stress.
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Affiliation(s)
- Abhishek D Garg
- Cell Death Research and Therapy Unit, Department of Cellular and Molecular Medicine KU Leuven, KU Leuven, Leuven, Belgium
| | - Dmitri V Krysko
- Molecular Signaling and Cell Death Unit, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Tom Verfaillie
- Cell Death Research and Therapy Unit, Department of Cellular and Molecular Medicine KU Leuven, KU Leuven, Leuven, Belgium
| | - Agnieszka Kaczmarek
- Molecular Signaling and Cell Death Unit, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Gabriela B Ferreira
- Laboratory for Experimental Medicine and Endocrinology (LEGENDO), Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Thierry Marysael
- Laboratory for Pharmaceutical Biology, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Noemi Rubio
- Cell Death Research and Therapy Unit, Department of Cellular and Molecular Medicine KU Leuven, KU Leuven, Leuven, Belgium
| | - Malgorzata Firczuk
- Department of Immunology, Centre of Biostructure Research, Medical University of Warsaw, Warsaw, Poland
- Department 3, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Chantal Mathieu
- Laboratory for Experimental Medicine and Endocrinology (LEGENDO), Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Anton J M Roebroek
- Experimental Mouse Genetics, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Wim Annaert
- Laboratory for Membrane Trafficking, Department of Human Genetics, KU Leuven and VIB-Center for the Biology of Disease, Leuven, Belgium
| | - Jakub Golab
- Department of Immunology, Centre of Biostructure Research, Medical University of Warsaw, Warsaw, Poland
- Department 3, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Peter de Witte
- Laboratory for Pharmaceutical Biology, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Peter Vandenabeele
- Molecular Signaling and Cell Death Unit, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Patrizia Agostinis
- Cell Death Research and Therapy Unit, Department of Cellular and Molecular Medicine KU Leuven, KU Leuven, Leuven, Belgium
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Wang P, Liu GH, Wu K, Qu J, Huang B, Zhang X, Zhou X, Gerace L, Chen C. Repression of classical nuclear export by S-nitrosylation of CRM1. J Cell Sci 2009; 122:3772-9. [PMID: 19812309 PMCID: PMC2758806 DOI: 10.1242/jcs.057026] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2009] [Indexed: 02/06/2023] Open
Abstract
The karyopherin chromosomal region maintenance 1 (CRM1) is the major receptor for classical nuclear protein export. However, little is known about the regulation of CRM1 itself. Here, we report that cellular CRM1 became S-nitrosylated after extensive exposure to endogenous or exogenous nitric oxide (NO). This abrogated the interaction of CRM1 with nuclear export signals (NESs) and repressed classical protein export. Analysis by mass spectrometry and involving the use of S-nitrosylation mimetic mutations indicated that modification at either of two specific cysteines of CRM1 was sufficient to abolish the CRM1-NES association. Moreover, ectopic overexpression of the corresponding S-nitrosylation-resistant CRM1 mutants rescued NO-induced repression of nuclear export. We also found that inactivation of CRM1 by NO facilitated the nuclear accumulation of the antioxidant response transcription factor Nrf2 and transcriptional activation of Nrf2-controlled genes. Together, these data demonstrate that CRM1 is negatively regulated by S-nitrosylation under nitrosative stress. We speculate that this is important for promoting a cytoprotective transcriptional response to nitrosative stress.
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Affiliation(s)
- Peng Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 PR China
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Torriglia A, Leprêtre C, Padrón-Barthe L, Chahory S, Martin E. Molecular mechanism of L-DNase II activation and function as a molecular switch in apoptosis. Biochem Pharmacol 2008; 76:1490-502. [DOI: 10.1016/j.bcp.2008.07.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 07/14/2008] [Accepted: 07/15/2008] [Indexed: 01/22/2023]
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Leprêtre C, Fleurier Y, Martin E, Torriglia A. Nuclear export of LEI/L-DNase II by Crm1 is essential for cell survival. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1783:1068-75. [PMID: 18342633 DOI: 10.1016/j.bbamcr.2008.02.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 02/05/2008] [Accepted: 02/05/2008] [Indexed: 01/24/2023]
Abstract
LEI/L-DNase II is the key protein of a caspase-independent pathway activated by serine proteases. LEI (Leukocyte elastase inhibitor), L-DNase II precursor, is a member of the clade B serpins (also called serpin b1). In its native conformation it inhibits several intracellular proteases and has an anti-apoptotic activity. Following a metabolic stress and the increase of protease activity in the cell, LEI is cleaved and transformed into L-DNase II (LEI-derived DNase II). This transformation is due to a conformational modification that exposes a nuclear localization signal and an endonuclease active site. In this paper we show that LEI can bind the exportin Crm1, and we identify on LEI a nuclear export signal involved in the control of LEI/L-DNase II nuclearization in healthy cells. Point mutation of this site increases the accumulation of the molecule in the nucleus and triggers cell death.
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Moshynskyy I, Viswanathan S, Vasilenko N, Lobanov V, Petric M, Babiuk LA, Zakhartchouk AN. Intracellular localization of the SARS coronavirus protein 9b: evidence of active export from the nucleus. Virus Res 2007; 127:116-21. [PMID: 17448558 PMCID: PMC7114319 DOI: 10.1016/j.virusres.2007.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 03/08/2007] [Accepted: 03/14/2007] [Indexed: 01/29/2023]
Abstract
Open reading frame 9b (ORF 9b) encodes a 98 amino acid group-specific protein of severe acute respiratory syndrome (SARS) coronavirus (CoV). It has no homology with known proteins and its function in SARS CoV replication has not been determined. The N-terminal part of the 9b protein was used to raise polyclonal antibodies in rabbits, and these antibodies could detect 9b protein in infected cells. We analyzed the sub-cellular localization of recombinant 9b protein using fluorescence microscopy of live transfected cells and indirect immunofluorescence of transfected fixed cells. Our findings indicate that the 9b protein is exported outside of a cell nucleus and localizes to the endoplasmic reticulum. Our data also suggest that the 46-LRLGSQLSL-54 amino acid sequence of 9b functions as a nuclear export signal (NES).
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Affiliation(s)
- Igor Moshynskyy
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
| | - Sathiyanarayanan Viswanathan
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
| | - Natalia Vasilenko
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
| | - Vladislav Lobanov
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
| | - Martin Petric
- The University of British Columbia Centre for Disease Control, Vancouver, BC V5Z 4R4, Canada
| | - Lorne A. Babiuk
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
| | - Alexander N. Zakhartchouk
- Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada
- Corresponding author. Tel.: +1 306 966 1570; fax: +1 306 966 7478.
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Blink EJ, Jiansheng Z, Hu W, Calanni ST, Trapani JA, Bird PI, Jans DA. Interaction of the nuclear localizing cytolytic granule serine protease granzyme B with importin alpha or beta: modulation by the serpin inhibitor PI-9. J Cell Biochem 2005; 95:598-610. [PMID: 15791691 DOI: 10.1002/jcb.20415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Conditional on perforin-dependent delivery to the nucleus of target cells, the cytolytic granule serine protease granzyme B (GrB) plays a central role in eliciting the nuclear events of apoptosis, as shown by the fact that reducing GrB nuclear entry prevents nuclear apoptosis. Apart from a requirement for cytosolic factors and lack of dependence on the guanine-nucleotide-binding protein Ran, little is known regarding the nuclear import pathway of GrB. In this study we use quantitative yeast two-hybrid and direct binding assays to show that GrB can be recognized independently by either of the nuclear import receptor family members importin (IMP) alpha and beta1, but that these proteins either alone or in combination cannot replace exogenous cytosol to reconstitute GrB nuclear import in vitro. Whereas antibodies to IMP(alpha) inhibit transport, indicating that IMP(alpha) is required for GrB nuclear import, those to IMP(beta) enhance transport, implying that IMP(beta) inhibits GrB nuclear import; consistent with this, the addition of recombinant IMP(beta) but not IMP(alpha) reduces maximal nuclear accumulation in the presence of cytosol. Intriguingly, complexation of GrB with its specific serpin inhibitor PI-9 was found to prevent recognition by IMP(beta) but not by IMP(alpha), and eliminate the apparent requirement for IMP(alpha) for nuclear import. We conclude that GrB nuclear import exhibits complex regulation by IMPs; that heterodimerization with PI-9 can modulate the interaction has implications for protection against apoptosis.
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Affiliation(s)
- Elizabeth J Blink
- Nuclear Signalling Laboratory, Division for Biochemistry and Molecular Biology, John Curtin School of Medical Research, Canberra City, Australia
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Simonovic M, Denault JB, Salvesen GS, Volz K, Gettins PGW. Lack of involvement of strand s1′A of the viral serpin CrmA in anti-apoptotic or caspase-inhibitory functions. Arch Biochem Biophys 2005; 440:1-9. [PMID: 15993378 DOI: 10.1016/j.abb.2005.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 05/12/2005] [Accepted: 05/13/2005] [Indexed: 11/15/2022]
Abstract
CrmA is a cowpox virus serpin required for full host infectivity and virulence. Residues 51-56 (DKNKDD), the only region that differs significantly from related viral serpins, were investigated for functional importance. A 1.6A X-ray structure reported here showed that this region can adopt either structured or unstructured conformations. Three variants were expressed, one with the region 51-56 deleted, one substituted by alanines, and one in which this region was replaced by the sequence encoded in smallpox virus. NMR showed that the region is an exposed, flexible loop that can be deleted without perturbing the serpin. The region is also very susceptible to proteolysis. Significantly, inhibition of caspases 1 and 8 was unaffected by the mutations, and each of the variants was as effective as wild-type CrmA in promoting survival from apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Thus, although the 51-56 region of CrmA is unique, and is exposed and highly susceptible to proteolysis, any in vivo role must involve a function other than proteinase inhibition or cell sparing.
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Affiliation(s)
- Miljan Simonovic
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, USA
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Kurooka H, Yokota Y. Nucleo-cytoplasmic shuttling of Id2, a negative regulator of basic helix-loop-helix transcription factors. J Biol Chem 2004; 280:4313-20. [PMID: 15563451 DOI: 10.1074/jbc.m412614200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Id proteins function as negative regulators for basic helix-loop-helix transcriptional factors that play important roles in cell fate determination. They preferentially associate with ubiquitously expressed E proteins of the basic helix-loop-helix family and prevent them from binding to DNA and activating transcription. Although their small size suggests that Id proteins enter and exit the nucleus by passive diffusion, several studies have indicated that other pathways may regulate their subcellular localization. In this study, we obtained evidence that Id2 has the ability to shuttle between the nucleus and the cytoplasm. When passive diffusion was prevented by fusion with green fluorescent protein (GFP), Id2 was predominantly localized in the cytoplasm. Using GFP fusion constructs, we demonstrated that the C-terminal region is required for cytoplasmic localization. Nuclear accumulation of GFP-Id2 in cells treated with the nuclear export inhibitor leptomycin B suggests that the nuclear export receptor chromosome region maintenance protein 1 mediates the cytoplasmic localization of Id2. Id2 contains two putative leucine-rich nuclear export signals, and the nuclear export signal in the C-terminal region is essential for nuclear export. On the other hand, the helix-loop-helix domain is important for nuclear localization. Finally, experiments using reporter assays revealed an inverse correlation between nuclear export and transcriptional repression via the E-box sequence. Based on all these findings, we propose that nucleo-cytoplasmic shuttling is a novel mechanism for the regulation of Id2 function.
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Affiliation(s)
- Hisanori Kurooka
- Department of Molecular Genetics, School of Medicine, University of Fukui, 23-3, Shimoaizuki, Matsuoka, Fukui 910-1193, Japan
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Danielli A, Barillas-Mury C, Kumar S, Kafatos FC, Loukeris TG. Overexpression and altered nucleocytoplasmic distribution of Anopheles ovalbumin-like SRPN10 serpins in Plasmodium-infected midgut cells. Cell Microbiol 2004; 7:181-90. [PMID: 15659062 DOI: 10.1111/j.1462-5822.2004.00445.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The design of effective, vector-based malaria transmission blocking strategies relies on a thorough understanding of the molecular and cellular interactions that occur during the parasite sporogonic cycle in the mosquito. During Plasmodium berghei invasion, transcription from the SRPN10 locus, encoding four serine protease inhibitors of the ovalbumin family, is strongly induced in the mosquito midgut. Herein we demonstrate that intense induction as well as redistribution of SRPN10 occurs specifically in the parasite-invaded midgut epithelial cells. Quantitative analysis establishes that in response to epithelial invasion, SRPN10 translocates from the nucleus to the cytoplasm and this is followed by strong SRPN10 overexpression. The invaded cells exhibit signs of apoptosis, suggesting a link between this type of intracellular serpin and epithelial damage. The SRPN10 gene products constitute a novel, robust and cell-autonomous marker of midgut invasion by ookinetes. The SRPN10 dynamics at the subcellular level confirm and further elaborate the 'time bomb' model of P. berghei invasion in both Anopheles stephensi and Anopheles gambiae. In contrast, this syndrome of responses is not elicited by mutant P. berghei ookinetes lacking the major ookinete surface proteins, P28 and P25. Molecular markers with defined expression patterns, in combination with mutant parasite strains, will facilitate dissection of the molecular mechanisms underlying vector competence and development of effective transmission blocking strategies.
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Affiliation(s)
- Alberto Danielli
- European Molecular Biology Laboratory (EMBL), Meyerhoftrasse 1, 69117 Heidelberg, Germany
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Vischioni B, Giaccone G, Span SW, Kruyt FAE, Rodriguez JA. Nuclear shuttling and TRAF2-mediated retention in the cytoplasm regulate the subcellular localization of cIAP1 and cIAP2. Exp Cell Res 2004; 298:535-48. [PMID: 15265700 DOI: 10.1016/j.yexcr.2004.04.040] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2003] [Revised: 03/10/2004] [Indexed: 11/29/2022]
Abstract
Dynamic subcellular localization is an important regulatory mechanism for many proteins. cIAP1 and cIAP2 are two closely related members of inhibitor of apoptosis (IAP) family that play a role both as caspase inhibitors and as mediators of tumor necrosis factor (TNF) receptor signaling. Here, we report that cIAP1 and cIAP2 are nuclear shuttling proteins, whose subcellular localization is mediated by the CRM1-dependent nuclear export pathway. Blocking export with leptomycin B induces accumulation of both endogenous cIAP1 and epitope-tagged cIAP1 and cIAP2 in the nucleus of human cancer cells. We have identified a new CRM1-dependent leucine-rich nuclear export signal (NES) in the linker region between cIAP1 BIR2 and BIR3 repeats. Mutational inactivation of the NES, which is not conserved in cIAP2, reduces cIAP1 nuclear export. Forced relocation of cIAP1 to the nucleus did not significantly alter its ability to prevent apoptosis. Interestingly, co-expression experiments showed that the cIAP1 and cIAP2-interacting protein TNF receptor-associated factor 2 (TRAF2) plays an important role as regulator of IAP nucleocytoplasmic localization, by preventing nuclear translocation of cIAP1 and cIAP2. TRAF2-mediated cytoplasmic retention of cIAP1 was reduced upon TNFalpha treatment. Our results identify molecular mechanisms that contribute to regulate the subcellular localization of cIAP1 and cIAP2. Translocation between different cell compartments may add a further level of control for cIAP1 and cIAP2 activity.
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Affiliation(s)
- Barbara Vischioni
- Department of Medical Oncology, VU University Medical Center, HV1081 Amsterdam, The Netherlands
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