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CrmA orthologs from diverse poxviruses potently inhibit caspases-1 and -8, yet cleavage site mutagenesis frequently produces caspase-1-specific variants. Biochem J 2019; 476:1335-1357. [PMID: 30992316 DOI: 10.1042/bcj20190202] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/15/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022]
Abstract
Poxviruses encode many proteins that enable them to evade host anti-viral defense mechanisms. Spi-2 proteins, including Cowpox virus CrmA, suppress anti-viral immune responses and contribute to poxviral pathogenesis and lethality. These proteins are 'serpin' protease inhibitors, which function via a pseudosubstrate mechanism involving initial interactions between the protease and a cleavage site within the serpin. A conformational change within the serpin interrupts the cleavage reaction, deforming the protease active site and preventing dissociation. Spi-2 proteins like CrmA potently inhibit caspases-1, -4 and -5, which produce proinflammatory cytokines, and caspase-8, which facilitates cytotoxic lymphocyte-mediated target cell death. It is not clear whether both of these functions are equally perilous for the virus, or whether only one must be suppressed for poxviral infectivity and spread but the other is coincidently inhibited merely because these caspases are biochemically similar. We compared the caspase specificity of CrmA to three orthologs from orthopoxviruses and four from more distant chordopoxviruses. All potently blocked caspases-1, -4, -5 and -8 activity but exhibited negligible inhibition of caspases-2, -3 and -6. The orthologs differed markedly in their propensity to inhibit non-mammalian caspases. We determined the specificity of CrmA mutants bearing various residues in positions P4, P3 and P2 of the cleavage site. Almost all variants retained the ability to inhibit caspase-1, but many lacked caspase-8 inhibitory activity. The retention of Spi-2 proteins' caspase-8 specificity during chordopoxvirus evolution, despite this function being readily lost through cleavage site mutagenesis, suggests that caspase-8 inhibition is crucial for poxviral pathogenesis and spread.
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2
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Kasperkiewicz P, Altman Y, D'Angelo M, Salvesen GS, Drag M. Toolbox of Fluorescent Probes for Parallel Imaging Reveals Uneven Location of Serine Proteases in Neutrophils. J Am Chem Soc 2017; 139:10115-10125. [PMID: 28672107 DOI: 10.1021/jacs.7b04394] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Neutrophils, the front line defenders against infection, express four serine proteases (NSPs) that play roles in the control of cell-signaling pathways and defense against pathogens and whose imbalance leads to pathological conditions. Dissecting the roles of individual NSPs in humans is problematic because neutrophils are end-stage cells with a short half-life and minimal ongoing protein synthesis. To gain insight into the regulation of NSP activity we have generated a small-molecule chemical toolbox consisting of activity-based probes with different fluorophore-detecting groups with minimal wavelength overlap and highly selective natural and unnatural amino acid recognition sequences. The key feature of these activity-based probes is the ability to use them for simultaneous observation and detection of all four individual NSPs by fluorescence microscopy, a feature never achieved in previous studies. Using these probes we demonstrate uneven distribution of NSPs in neutrophil azurophil granules, such that they seem to be mutually excluded from each other, suggesting the existence of unknown granule-targeting mechanisms.
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Affiliation(s)
- Paulina Kasperkiewicz
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland.,NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute , La Jolla, California 92037, United States
| | - Yoav Altman
- NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute , La Jolla, California 92037, United States
| | - Maximiliano D'Angelo
- NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute , La Jolla, California 92037, United States
| | - Guy S Salvesen
- NCI-designated Cancer Center, Sanford-Burnham Prebys Medical Discovery Institute , La Jolla, California 92037, United States
| | - Marcin Drag
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
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3
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Abstract
One of the most valuable tools that have been developed for the study of apoptosis is the availability of recombinant active caspases. The determination of caspase substrate preference, the design of sensitive substrates and potent inhibitors, the resolution of caspase structures, the elucidation of their activation mechanisms, and the identification of their substrates were made possible by the availability of sufficient amounts of enzymatically pure caspases. The current chapter describes at length the expression, purification, and basic enzymatic characterization of apoptotic caspases.
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Affiliation(s)
- Dave Boucher
- Institute of Molecular Bioscience, University of Queensland, St. Lucia, QLD, Australia
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4
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Brand IL, Civciristov S, Taylor NL, Talbo GH, Pantaki-Eimany D, Levina V, Clem RJ, Perugini MA, Kvansakul M, Hawkins CJ. Caspase inhibitors of the P35 family are more active when purified from yeast than bacteria. PLoS One 2012; 7:e39248. [PMID: 22720082 PMCID: PMC3375223 DOI: 10.1371/journal.pone.0039248] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 05/22/2012] [Indexed: 11/19/2022] Open
Abstract
Many insect viruses express caspase inhibitors of the P35 superfamily, which prevent defensive host apoptosis to enable viral propagation. The prototypical P35 family member, AcP35 from Autographa californica M nucleopolyhedrovirus, has been extensively studied. Bacterially purified AcP35 has been previously shown to inhibit caspases from insect, mammalian and nematode species. This inhibition occurs via a pseudosubstrate mechanism involving caspase-mediated cleavage of a "reactive site loop" within the P35 protein, which ultimately leaves cleaved P35 covalently bound to the caspase's active site. We observed that AcP35 purifed from Saccharomyces cerevisae inhibited caspase activity more efficiently than AcP35 purified from Escherichia coli. This differential potency was more dramatic for another P35 family member, MaviP35, which inhibited human caspase 3 almost 300-fold more potently when purified from yeast than bacteria. Biophysical assays revealed that MaviP35 proteins produced in bacteria and yeast had similar primary and secondary structures. However, bacterially produced MaviP35 possessed greater thermal stability and propensity to form higher order oligomers than its counterpart purified from yeast. Caspase 3 could process yeast-purified MaviP35, but failed to detectably cleave bacterially purified MaviP35. These data suggest that bacterially produced P35 proteins adopt subtly different conformations from their yeast-expressed counterparts, which hinder caspase access to the reactive site loop to reduce the potency of caspase inhibition, and promote aggregation. These data highlight the differential caspase inhibition by recombinant P35 proteins purified from different sources, and caution that analyses of bacterially produced P35 family members (and perhaps other types of proteins) may underestimate their activity.
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Affiliation(s)
- Ingo L. Brand
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
| | - Srgjan Civciristov
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
| | - Nicole L. Taylor
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Gert H. Talbo
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
| | - Delara Pantaki-Eimany
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
| | - Vita Levina
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
| | - Rollie J. Clem
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Matthew A. Perugini
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Marc Kvansakul
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
| | - Christine J. Hawkins
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Australia
- * E-mail:
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5
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Abstract
During apoptosis, initiator caspases (8, 9 and 10) activate downstream executioner caspases (3, 6 and 7) by cleaving the IDC (interdomain connector) at two sites. Here, we demonstrate that both activation sites, site 1 and site 2, of caspase 7 are suboptimal for activation by initiator caspases 8 and 9 in cellulo, and in vitro using recombinant proteins and activation kinetics. Indeed, when both sites are replaced with the preferred motifs recognized by either caspase 8 or 9, we found an up to 36-fold improvement in activation. Moreover, cleavage at site 1 is preferred to site 2 because of its location within the IDC, since swapping sites does not lead to a more efficient activation. We also demonstrate the important role of Ile195 of site 1 involved in maintaining a network of contacts that preserves the proper conformation of the active enzyme. Finally, we show that the length of the IDC plays a crucial role in maintaining the necessity of proteolysis for activation. In fact, although we were unable to generate a caspase 7 that does not require proteolysis for activity, shortening the IDC of the initiator caspase 8 by four residues was sufficient to confer a requirement for proteolysis, a key feature of executioner caspases. Altogether, the results demonstrate the critical role of the primary structure of caspase 7's IDC for its activation and proteolytic activity.
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Affiliation(s)
| | | | - Marcin DRAG
- Division of Medicinal Chemistry and Microbiology, Faculty of Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, POLAND
| | - Jean-Bernard DENAULT
- Corresponding author: Jean-Bernard Denault, Université de Sherbrooke, Faculty of medicine and health sciences, Pharmacology department, 3001, 12th Avenue North, Sherbrooke QC, J1H 5N4, CANADA, Phone: +1-819-820-6868 x12789, Fax: +1-819-564-5400,
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6
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Tenev T, Bianchi K, Darding M, Broemer M, Langlais C, Wallberg F, Zachariou A, Lopez J, MacFarlane M, Cain K, Meier P. The Ripoptosome, a signaling platform that assembles in response to genotoxic stress and loss of IAPs. Mol Cell 2011; 43:432-48. [PMID: 21737329 DOI: 10.1016/j.molcel.2011.06.006] [Citation(s) in RCA: 729] [Impact Index Per Article: 56.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 05/16/2011] [Accepted: 06/08/2011] [Indexed: 10/18/2022]
Abstract
A better understanding of the mechanisms through which anticancer drugs exert their effects is essential to improve combination therapies. While studying how genotoxic stress kills cancer cells, we discovered a large ∼2MDa cell death-inducing platform, referred to as "Ripoptosome." It contains the core components RIP1, FADD, and caspase-8, and assembles in response to genotoxic stress-induced depletion of XIAP, cIAP1 and cIAP2. Importantly, it forms independently of TNF, CD95L/FASL, TRAIL, death-receptors, and mitochondrial pathways. It also forms upon Smac-mimetic (SM) treatment without involvement of autocrine TNF. Ripoptosome assembly requires RIP1's kinase activity and can stimulate caspase-8-mediated apoptosis as well as caspase-independent necrosis. It is negatively regulated by FLIP, cIAP1, cIAP2, and XIAP. Mechanistically, IAPs target components of this complex for ubiquitylation and inactivation. Moreover, we find that etoposide-stimulated Ripoptosome formation converts proinflammatory cytokines into prodeath signals. Together, our observations shed new light on fundamental mechanisms by which chemotherapeutics may kill cancer cells.
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Affiliation(s)
- Tencho Tenev
- The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, London, UK.
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7
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Rennenberg A, Lehmann C, Heitmann A, Witt T, Hansen G, Nagarajan K, Deschermeier C, Turk V, Hilgenfeld R, Heussler VT. Exoerythrocytic Plasmodium parasites secrete a cysteine protease inhibitor involved in sporozoite invasion and capable of blocking cell death of host hepatocytes. PLoS Pathog 2010; 6:e1000825. [PMID: 20361051 PMCID: PMC2845656 DOI: 10.1371/journal.ppat.1000825] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Accepted: 02/18/2010] [Indexed: 11/18/2022] Open
Abstract
Plasmodium parasites must control cysteine protease activity that is critical for hepatocyte invasion by sporozoites, liver stage development, host cell survival and merozoite liberation. Here we show that exoerythrocytic P. berghei parasites express a potent cysteine protease inhibitor (PbICP, P. berghei inhibitor of cysteine proteases). We provide evidence that it has an important function in sporozoite invasion and is capable of blocking hepatocyte cell death. Pre-incubation with specific anti-PbICP antiserum significantly decreased the ability of sporozoites to infect hepatocytes and expression of PbICP in mammalian cells protects them against peroxide- and camptothecin-induced cell death. PbICP is secreted by sporozoites prior to and after hepatocyte invasion, localizes to the parasitophorous vacuole as well as to the parasite cytoplasm in the schizont stage and is released into the host cell cytoplasm at the end of the liver stage. Like its homolog falstatin/PfICP in P. falciparum, PbICP consists of a classical N-terminal signal peptide, a long N-terminal extension region and a chagasin-like C-terminal domain. In exoerythrocytic parasites, PbICP is posttranslationally processed, leading to liberation of the C-terminal chagasin-like domain. Biochemical analysis has revealed that both full-length PbICP and the truncated C-terminal domain are very potent inhibitors of cathepsin L-like host and parasite cysteine proteases. The results presented in this study suggest that the inhibitor plays an important role in sporozoite invasion of host cells and in parasite survival during liver stage development by inhibiting host cell proteases involved in programmed cell death.
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Affiliation(s)
- Annika Rennenberg
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
| | - Christine Lehmann
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
| | - Anna Heitmann
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
| | - Tina Witt
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
| | - Guido Hansen
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Lübeck, Germany
| | - Krishna Nagarajan
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Lübeck, Germany
| | - Christina Deschermeier
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
| | - Vito Turk
- Josef Stefan Institute, Department of Biochemistry, Molecular and Structural Biology, Ljubljana, Slovenia
| | - Rolf Hilgenfeld
- Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Lübeck, Germany
| | - Volker T. Heussler
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
- * E-mail:
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8
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Denault JB, Békés M, Scott FL, Sexton KMB, Bogyo M, Salvesen GS. Engineered hybrid dimers: tracking the activation pathway of caspase-7. Mol Cell 2006; 23:523-33. [PMID: 16916640 DOI: 10.1016/j.molcel.2006.06.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 05/19/2006] [Accepted: 06/07/2006] [Indexed: 11/18/2022]
Abstract
Caspase-7 is an obligate dimer of catalytic domains, with generation of activity requiring limited proteolysis within a region that separates the large and small chains of each domain. Using hybrid dimers we distinguish the relative contribution of each domain to catalysis by the whole molecule. We demonstrate that the zymogen arises from direct dimerization and not domain swapping. In contrast to previous conclusions, we show that only one of the catalytic domains must be proteolyzed to enable activation. The processed domain of this singly cleaved zymogen has the same catalytic activity as a domain of fully active caspase-7. A transient intermediate of singly cleaved dimeric caspase-7 can be found in a cell-free model of apoptosis induction. However, we see no evidence for an analogous intermediate of the related executioner caspase-3. Our study demonstrates the efficiency by which the executioner caspases are activated in vivo.
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Affiliation(s)
- Jean-Bernard Denault
- The Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
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9
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Luttge BG, Moyer RW. Suppressors of a host range mutation in the rabbitpox virus serpin SPI-1 map to proteins essential for viral DNA replication. J Virol 2005; 79:9168-79. [PMID: 15994811 PMCID: PMC1168772 DOI: 10.1128/jvi.79.14.9168-9179.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The orthopoxvirus serpin SPI-1 is an intracellular serine protease inhibitor that is active against cathepsin G in vitro. Rabbitpox virus (RPV) mutants with deletions of the SPI-1 gene grow on monkey kidney cells (CV-1) but do not plaque on normally permissive human lung carcinoma cells (A549). This reduced-host-range (hr) phenotype suggests that SPI-1 may interact with cellular and/or other viral proteins. We devised a genetic screen for suppressors of SPI-1 hr mutations by first introducing a mutation into SPI-1 (T309R) at residue P14 of the serpin reactive center loop. The SPI-1 T309R serpin is inactive as a protease inhibitor in vitro. Introduction of the mutation into RPV leads to the same restricted hr phenotype as deletion of the SPI-1 gene. Second-site suppressors were selected by restoration of growth of the RPV SPI-1 T309R hr mutant on A549 cells. Both intragenic and extragenic suppressors of the T309R mutation were identified. One novel intragenic suppressor mutation, T309C, restored protease inhibition by SPI-1 in vitro. Extragenic suppressor mutations were mapped by a new procedure utilizing overlapping PCR products encompassing the entire genome in conjunction with marker rescue. One suppressor mutation, which also rendered the virus temperature sensitive for growth, mapped to the DNA polymerase gene (E9L). Several other suppressors mapped to gene D5R, an NTPase required for DNA replication. These results unexpectedly suggest that the host range function of SPI-1 may be associated with viral DNA replication by an as yet unknown mechanism.
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Affiliation(s)
- Benjamin G Luttge
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, P.O. Box 100266, Gainesville, FL 32610.
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10
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Li Q, Liston P, Moyer RW. Functional analysis of the inhibitor of apoptosis (iap) gene carried by the entomopoxvirus of Amsacta moorei. J Virol 2005; 79:2335-45. [PMID: 15681434 PMCID: PMC546542 DOI: 10.1128/jvi.79.4.2335-2345.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2004] [Accepted: 09/13/2004] [Indexed: 02/02/2023] Open
Abstract
The entomopoxvirus from Amsacta moorei (AmEPV) contains none of the commonly recognized vertebrate poxvirus apoptotic suppressor genes. However, AmEPV carries a single inhibitor of apoptosis (iap) gene (AMViap) not present in vertebrate poxviruses. The AMViap gene was active when coexpressed with the Drosophila proapoptotic gene hid in Ld652 cells and can rescue cells from apoptosis as shown by increased number of surviving cells and reduced levels of caspase-3-like activity. We also showed that expression of the AMViap gene rescued polyhedron production in Autographa californica M nucleopolyhedrovirus (AcMNPV)Deltap35-infected Sf9 cells during an otherwise abortive infection induced by apoptosis. Surprisingly, deletion of the AMViap gene from the AmEPV genome led to only a modest (10-fold) loss of virion production in infected Ld652 cells, indicating that the AMViap gene is nonessential for virus replication under these conditions. However, infection of Ld652 cells by AmEPV lacking a functional iap gene led to a more rapid induction of cytotoxicity and increased levels of caspase-3-like activity. Similar results were observed and were more pronounced in infected Sf9 and S2 cells. The purified AMVIAP protein also inhibits the enzymatic activities of human caspase-9 and caspase-3 in vitro. Our results indicate that while the AMViap gene was active in controlling apoptosis through the intrinsic pathway, the virus likely encodes additional proteins that also regulate apoptosis.
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Affiliation(s)
- Qianjun Li
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610-0266, USA
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11
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Abstract
The understanding of the apoptotic program has grown exponentially over the past decade. Numerous human diseases have been directly linked to genetic defects in the apoptotic pathways, including cancer, neurodegenerative disorders, and autoimmune diseases. Caspases initiate and amplify various death signals, allowing for selective and ordered cellular demolition. The fine balance between pro- and antiapoptotic Bcl-2 family members regulates the cell fate in response to many (but not all) stress or signaling pathways. Recent discoveries highlight the complex integration of signals from various organelles that determine cell fate and the multiple functions of central players in the apoptotic process. It is likely that the knowledge obtained in a relatively time will translate into better diagnostics and therapies to enhance or retard cell death in the appropriate clinical circumstances.
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Affiliation(s)
- David A Martin
- Division of Rheumatology, University of Washington, 1959 NE Pacific Avenue, Box 356428, Seattle, WA 98195, USA
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12
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Yang J, Hooper WC, Phillips DJ, Talkington DF. Interleukin-1beta responses to Mycoplasma pneumoniae infection are cell-type specific. Microb Pathog 2003; 34:17-25. [PMID: 12620381 DOI: 10.1016/s0882-4010(02)00190-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Interleukin-1beta (IL-1beta) is a major proinflammatory cytokine that is involved in many important cellular functions such as proliferation, differentiation, and activation of different cell types. Its mature form is released from the cells in response to various bacterial and viral infections, and it plays a significant role in host defense. Mycoplasma pneumoniae is a small bacterium without a cell wall that causes tracheobronchitis and atypical pneumonia in humans following attachment to respiratory epithelium, as well as extrapulmonary infections. Very little is known about the role of cytokines in pathogenesis or the response of target cells to M.pneumoniae attachment. The purpose of this study was to investigate the ability of M. pneumoniae to induce IL-1beta in human lung epithelial carcinoma A549 and in human monocytic U937 cell lines. Following M. pneumoniae infection, both IL-1beta mRNA and protein were induced in A549 cells vs. no induction in uninfected cells; however, the protein remained inside the A549 cells. Similarly, M. pneumoniae infection strongly increased mRNA and extracellular protein levels in U937 cells, which unlike A549 cells did exhibit baseline constitutive levels. De novo IL-1beta protein expression was verified by cycloheximide studies. M. pneumoniae infection did not affect constitutive caspase-1 mRNA or protein levels in either cell line. Reduced caspase-1 activity in A549 cell lysates suggests the presence of an endogenous caspase-1 inhibitory component in the A549 cells. These collective data confirm previous studies that show that M. pneumoniae is a potent inducer of cytokines following adherence to host target cells, and establish that IL-1beta release in response to M. pneumoniae infection is cell-type specific, thus emphasizing the importance of carefully considering multiple cell types in M. pneumoniae pathogenesis studies involving both immune cells and cytokine release patterns.
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Affiliation(s)
- Jun Yang
- Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Mail Stop G03, 1600 Clifton Road NE, Atlanta, GA 30333, USA
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13
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Feng P, Park J, Lee BS, Lee SH, Bram RJ, Jung JU. Kaposi's sarcoma-associated herpesvirus mitochondrial K7 protein targets a cellular calcium-modulating cyclophilin ligand to modulate intracellular calcium concentration and inhibit apoptosis. J Virol 2002; 76:11491-504. [PMID: 12388711 PMCID: PMC136794 DOI: 10.1128/jvi.76.22.11491-11504.2002] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
On viral infection, infected cells can become the target of host immune responses or can go through a programmed cell death process, called apoptosis, as a defense mechanism to limit the ability of the virus to replicate. To prevent this, viruses have evolved elaborate mechanisms to subvert the apoptotic process. Here, we report the identification of a novel antiapoptotic K7 protein of Kaposi's sarcoma-associated herpesvirus (KSHV) which expresses during lytic replication. The KSHV K7 gene encodes a small mitochondrial membrane protein, and its expression efficiently inhibits apoptosis induced by a variety of apoptogenic agents. The yeast two-hybrid screen has demonstrated that K7 targets cellular calcium-modulating cyclophilin ligand (CAML), a protein that regulates the intracellular Ca(2+) concentration. Similar to CAML, K7 expression significantly enhances the kinetics and amplitudes of the increase in intracellular Ca(2+) concentration on apoptotic stimulus. Mutational analysis showed that K7 interaction with CAML is required for its function in the inhibition of apoptosis. This indicates that K7 targets cellular CAML to increase the cytosolic Ca(2+) response, which consequently protects cells from mitochondrial damage and apoptosis. This is a novel viral antiapoptosis strategy where the KSHV mitochondrial K7 protein targets a cellular Ca(2+)-modulating protein to confer resistance to apoptosis, which allows completion of the viral lytic replication and, eventually, maintenance of persistent infection in infected host.
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Affiliation(s)
- Pinghui Feng
- Department of Microbiology and Molecular Genetics and Tumor Virology Division, New England Regional Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772, USA
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14
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Pedersen IM, Kitada S, Schimmer A, Kim Y, Zapata JM, Charboneau L, Rassenti L, Andreeff M, Bennett F, Sporn MB, Liotta LD, Kipps TJ, Reed JC. The triterpenoid CDDO induces apoptosis in refractory CLL B cells. Blood 2002; 100:2965-72. [PMID: 12351409 DOI: 10.1182/blood-2002-04-1174] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Chronic lymphocytic leukemia (CLL) cells develop chemo-resistance over time. Most anticancer agents function through induction of apoptosis, and therefore resistance against these agents is likely to be caused by selection for CLL cells with defects in the particular apoptosis pathway that is triggered by these drugs. Anticancer agents that function through alternative apoptotic pathways might therefore be useful in treating chemo-resistant CLL. Triterpenoids represent a class of naturally occurring and synthetic compounds with demonstrated antitumor activity. We examined the effects of CDDO (triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid) on CLL B cells in vitro. CDDO induced apoptosis in a dose-dependent manner in all (n = 30) CLL samples tested, including previously untreated and chemo-resistant CLL specimens. CDDO induced rapid proteolytic processing of caspase-8, but not caspase-9, in CLL B cells, suggesting activation of a mitochondria-independent pathway. CDDO-induced apoptosis of CLL B cells was blocked by cytokine response modifier A (CrmA), a suppressor of caspase-8, but not by X-linked inhibitor of apoptosis protein-baculovirus IAP repeat-3 (XIAP-BIR3), a fragment of XIAP, which selectively inhibits caspase-9. Examination of CDDO effects on expression of several apoptosis-relevant genes demonstrated significant reductions in the levels of caspase-8 homolog Fas-ligand interleukin-1-converting enzyme (FLICE)-inhibitory protein (c-FLIP), an endogenous antagonist of caspase-8. However, reductions of FLIP achieved by FLIP antisense oligonucleotides were insufficient for triggering apoptosis, indicating that CDDO has other targets in CLL B cells besides FLIP. These data suggest that the synthetic triterpenoid CDDO should be further explored as a possible therapeutic agent for treatment of chemo-resistant CLL.
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MESH Headings
- Antineoplastic Agents/therapeutic use
- Antineoplastic Agents/toxicity
- Apoptosis/drug effects
- B-Lymphocytes/drug effects
- B-Lymphocytes/pathology
- Caspases/blood
- Drug Resistance, Neoplasm
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/blood
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Nitric Oxide/antagonists & inhibitors
- Oleanolic Acid/analogs & derivatives
- Oleanolic Acid/pharmacology
- Vidarabine/analogs & derivatives
- Vidarabine/therapeutic use
- Vidarabine/toxicity
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Affiliation(s)
- Irene M Pedersen
- The Burnham Institute and University of California-San Diego, La Jolla, CA 92037, USA
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15
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Mohamed AAA, Jupp OJ, Anderson HM, Littlejohn AF, Vandenabeele P, MacEwan DJ. Tumour necrosis factor-induced activation of c-Jun N-terminal kinase is sensitive to caspase-dependent modulation while activation of mitogen-activated protein kinase (MAPK) or p38 MAPK is not. Biochem J 2002; 366:145-55. [PMID: 11996667 PMCID: PMC1222751 DOI: 10.1042/bj20020527] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Revised: 04/30/2002] [Accepted: 05/08/2002] [Indexed: 01/08/2023]
Abstract
The activation of the extracellular signal-regulated kinases (ERKs) by tumour necrosis factor-alpha (TNF) receptors (TNFRs) is an integral part of the cytokine's pleiotropic cellular responses. Here we report differences in the caspase sensitivity and TNFR subtype activation of members of the ERK family. Inhibition in HeLa cells of caspase function by pharmacological inhibitors or the expression of CrmA (cytokine response modifier A), a viral modifier protein, blocks TNF-induced apoptosis or caspase-dependent protein kinase Cdelta and poly(ADP-ribose) polymerase protein degradation. TNFR1- or TNFR2-stimulated c-Jun N-terminal kinase (JNK) activity was attenuated in cells in which caspase activity was inhibited either by pharmacological blockers or CrmA expression. Both TNFR1- and TNFR2-stimulated JNK activity was caspase-sensitive; however, only TNFR1 was capable of stimulating p42/44 mitogen-activated protein kinase (MAPK) and p38 MAPK activities. TNFR1-stimulated p42/44 MAPK and p38 MAPK activities were insensitive to pharmacological caspase inhibition or CrmA. These findings were supported when measuring TNF-induced cytosolic phospholipase A(2) activation, which is a downstream target for MAPK and p38 MAPK. Profiling caspase enzymes activated by TNF in HeLa cells showed sequential caspase-8, -3, -7, -6 and -9 activation, with their inhibition characteristics suggesting a role for caspase-3 and/or caspase-6 in modulating JNK activity. Taken together these results show delineated ERK-activation pathways employed by TNFR subtypes.
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Affiliation(s)
- Ahmed A A Mohamed
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, U.K
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16
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Abstract
Apoptosis, also known as programmed cell death, is a ubiquitous mode of cell death known to play an important role during embryogenesis, development, and adult cellular homeostasis. Disruption of this normal physiological cell death process can result in either excessive or insufficient apoptosis, which can lead to various disease states and pathology. Since most cells contain the machinery that brings about apoptosis, it is clear that living cells must contain inherent repressive mechanisms to keep the death process in check. In this review, we examine several modes of repression of apoptosis that exist in cells.
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Affiliation(s)
- Carl D Bortner
- The Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
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17
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Araya R, Takahashi R, Nomura Y. Yeast two-hybrid screening using constitutive-active caspase-7 as bait in the identification of PA28gamma as an effector caspase substrate. Cell Death Differ 2002; 9:322-8. [PMID: 11859414 DOI: 10.1038/sj.cdd.4400949] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2001] [Accepted: 08/21/2001] [Indexed: 11/09/2022] Open
Abstract
Caspase-3 and -7 represent executioner/effector caspases that directly cause apoptotic morphological changes by cleaving various death substrates. The substrates for caspases generally interact with active caspases, but not with inactive zymogens of caspase or procaspases. Here, to isolate proteins that interact with caspase-7, we established a yeast two-hybrid screening system using reversed-caspase-7, a constitutive active mutant of caspase-7 as a bait plasmid. Screening of an adult brain cDNA library led to isolation of proteasome activator 28 subunit, PA28gamma. In vitro translates of PA28gamma were cleaved by both recombinant caspase-3 and -7. Mutagenesis of potential cleavage site DGLD80 to EGLE80 completely abolished caspase-mediated cleavage. Moreover, endogenous PA28gamma was cleaved during not only Fas-induced apoptosis of HeLa cells, but also cisplatin-induced cell death of MCF7 cells, which are devoid of caspase-3. These findings indicate that PA28gamma is an endogenous substrate for caspase-3 and -7 and that yeast two-hybrid screening using reversed-caspase is a novel and useful approach to clone substrates for effector caspases.
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Affiliation(s)
- R Araya
- Laboratory for Motor System Neurodegeneration, RIKEN Brain Science Institute, Saitama 351-0198, Japan
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18
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Stennicke HR, Ryan CA, Salvesen GS. Reprieval from execution: the molecular basis of caspase inhibition. Trends Biochem Sci 2002; 27:94-101. [PMID: 11852247 DOI: 10.1016/s0968-0004(01)02045-x] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The suppression of apoptosis is essential to the propagation of viruses, and to the control of development and homeostasis in insects and mammals. The central components of all apoptotic pathways are proteases of the caspase family. Therefore, it is not surprising that the processes of natural selection, as well as pharmaceutical chemists, have designed compounds that directly target caspase activity in attempts to regulate apoptosis. The mechanisms used by highly specialized naturally occurring caspase inhibitors (both host and viral) have remained obscure for some time. However, recently there has been significant progress in this field, particularly because of the structural elucidation of the complexes between caspases and an endogenous inhibitor (XIAP) and a viral inhibitor (p35). This article reviews the newly defined molecular basis for the regulation of the caspases by viral and endogenous inhibitors.
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Affiliation(s)
- Henning R Stennicke
- The Finsen Laboratory, Copenhagen University Hospital, Strandboulevarden 49, DK-2100 Copenhagen, Denmark
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19
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MacEwan DJ. TNF ligands and receptors--a matter of life and death. Br J Pharmacol 2002; 135:855-75. [PMID: 11861313 PMCID: PMC1573213 DOI: 10.1038/sj.bjp.0704549] [Citation(s) in RCA: 273] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2001] [Revised: 12/06/2001] [Accepted: 12/07/2001] [Indexed: 12/24/2022] Open
Affiliation(s)
- David J MacEwan
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD.
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20
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Riedl SJ, Renatus M, Schwarzenbacher R, Zhou Q, Sun C, Fesik SW, Liddington RC, Salvesen GS. Structural basis for the inhibition of caspase-3 by XIAP. Cell 2001; 104:791-800. [PMID: 11257232 DOI: 10.1016/s0092-8674(01)00274-4] [Citation(s) in RCA: 564] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The molecular mechanism(s) that regulate apoptosis by caspase inhibition remain poorly understood. The main endogenous inhibitors are members of the IAP family and are exemplified by XIAP, which regulates the initiator caspase-9, and the executioner caspases-3 and -7. We report the crystal structure of the second BIR domain of XIAP (BIR2) in complex with caspase-3, at a resolution of 2.7 A, revealing the structural basis for inhibition. The inhibitor makes limited contacts through its BIR domain to the surface of the enzyme, and most contacts to caspase-3 originate from the N-terminal extension. This lies across the substrate binding cleft, but in reverse orientation compared to substrate binding. The mechanism of inhibition is due to a steric blockade prohibitive of substrate binding, and is distinct from the mechanism utilized by synthetic substrate analog inhibitors.
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Affiliation(s)
- S J Riedl
- The Program in Apoptosis and Cell, Death Research, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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