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Ji Y, Hawkins CJ. Reconstitution of human pyroptotic cell death in Saccharomyces cerevisiae. Sci Rep 2023; 13:3095. [PMID: 36813876 PMCID: PMC9946934 DOI: 10.1038/s41598-023-29464-5] [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: 08/16/2022] [Accepted: 02/06/2023] [Indexed: 02/24/2023] Open
Abstract
Pyroptosis is a lytic form of programmed cell death induced by the activation of gasdermins. The precise mechanism of gasdermin activation by upstream proteases remains incompletely understood. Here, we reconstituted human pyroptotic cell death in yeast by inducible expression of caspases and gasdermins. Functional interactions were reflected by the detection of cleaved gasdermin-D (GSDMD) and gasdermin-E (GSDME), plasma membrane permeabilization, and reduced growth and proliferative potential. Following overexpression of human caspases-1, -4, -5, and -8, GSDMD was cleaved. Similarly, active caspase-3 induced proteolytic cleavage of co-expressed GSDME. Caspase-mediated cleavage of GSDMD or GSDME liberated the ~ 30 kDa cytotoxic N-terminal fragments of these proteins, permeabilized the plasma membrane and compromised yeast growth and proliferation potential. Interestingly, the observation of yeast lethality mediated by co-expression of caspases-1 or -2 with GSDME signified functional cooperation between these proteins in yeast. The small molecule pan-caspase inhibitor Q-VD-OPh reduced caspase-mediated yeast toxicity, allowing us to expand the utility of this yeast model to investigate the activation of gasdermins by caspases that would otherwise be highly lethal to yeast. These yeast biological models provide handy platforms to study pyroptotic cell death and to screen for and characterize potential necroptotic inhibitors.
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Affiliation(s)
- Yanhao Ji
- grid.1018.80000 0001 2342 0938Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC Australia
| | - Christine J. Hawkins
- grid.1018.80000 0001 2342 0938Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC Australia
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2
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Ohta T, Tanimura T, Kimura KI. A gain-of-function mutation in head involution defective , Wrinkled, causes precocious cell death of wing epidermal cells in Drosophila. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000703. [PMID: 36606079 PMCID: PMC9808536 DOI: 10.17912/micropub.biology.000703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/08/2022] [Accepted: 12/16/2022] [Indexed: 01/07/2023]
Abstract
In Drosophila , wing epidermal cells undergo programmed cell death as the last step of metamorphosis. The aim of this study was to evaluate the role of hid , particularly the Wrinkled mutation ( hid W ), an allele of hid , in the cell death. The wing epithelial cell death is suppressed by loss-of-function mutation of hid , indicating that the death is governed by a cascade involving hid . Examination of the cell death in hid W showed that precocious death started at G stage, 3 h before eclosion. Thus, mutated-HID in the hid W mutant was activated at G stage, supporting the gain-of-function effect of hid W mutation.
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Affiliation(s)
- Takumi Ohta
- Laboratory of Biology, Hokkaido University of Education, Sapporo Campus, Sapporo, Japan
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Department of Biology, Graduate School of Science, Kyushu University, Fukuoka, Japan
| | - Teiichi Tanimura
- Department of Biology, Graduate School of Science, Kyushu University, Fukuoka, Japan
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Present address: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Ken-ichi Kimura
- Laboratory of Biology, Hokkaido University of Education, Sapporo Campus, Sapporo, Japan
,
Correspondence to: Ken-ichi Kimura (
)
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3
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Russell SA, Laws KM, Bashaw GJ. Frazzled/Dcc acts independently of Netrin to promote germline survival during Drosophila oogenesis. Development 2021; 148:dev199762. [PMID: 34910816 PMCID: PMC8722396 DOI: 10.1242/dev.199762] [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: 04/29/2021] [Accepted: 11/16/2021] [Indexed: 11/20/2022]
Abstract
The Netrin receptor Frazzled/Dcc (Fra in Drosophila) functions in diverse tissue contexts to regulate cell migration, axon guidance and cell survival. Fra signals in response to Netrin to regulate the cytoskeleton and also acts independently of Netrin to directly regulate transcription during axon guidance in Drosophila. In other contexts, Dcc acts as a tumor suppressor by directly promoting apoptosis. In this study, we report that Fra is required in the Drosophila female germline for the progression of egg chambers through mid-oogenesis. Loss of Fra in the germline, but not the somatic cells of the ovary, results in the degeneration of egg chambers. Although a failure in nutrient sensing and disruptions in egg chamber polarity can result in degeneration at mid-oogenesis, these factors do not appear to be affected in fra germline mutants. However, similar to the degeneration that occurs in those contexts, the cell death effector Dcp-1 is activated in fra germline mutants. The function of Fra in the female germline is independent of Netrin and requires the transcriptional activation domain of Fra. In contrast to the role of Dcc in promoting cell death, our observations reveal a role for Fra in regulating germline survival by inhibiting apoptosis.
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Affiliation(s)
| | - Kaitlin M. Laws
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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4
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Zheng Q, Gao N, Sun Q, Li X, Wang Y, Xiao H. bfc, a novel serpent co-factor for the expression of croquemort, regulates efferocytosis in Drosophila melanogaster. PLoS Genet 2021; 17:e1009947. [PMID: 34860835 PMCID: PMC8673676 DOI: 10.1371/journal.pgen.1009947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 12/15/2021] [Accepted: 11/15/2021] [Indexed: 01/01/2023] Open
Abstract
Efferocytosis is the process by which phagocytes recognize, engulf, and digest (or clear) apoptotic cells during development. Impaired efferocytosis is associated with developmental defects and autoimmune diseases. In Drosophila melanogaster, recognition of apoptotic cells requires phagocyte surface receptors, including the scavenger receptor CD36-related protein, Croquemort (Crq, encoded by crq). In fact, Crq expression is upregulated in the presence of apoptotic cells, as well as in response to excessive apoptosis. Here, we identified a novel gene bfc (booster for croquemort), which plays a role in efferocytosis, specifically the regulation of the crq expression. We found that Bfc protein interacts with the zinc finger domain of the GATA transcription factor Serpent (Srp), to enhance its direct binding to the crq promoter; thus, they function together in regulating crq expression and efferocytosis. Overall, we show that Bfc serves as a Srp co-factor to upregulate the transcription of the crq encoded receptor, and consequently boosts macrophage efferocytosis in response to excessive apoptosis. Therefore, this study clarifies how phagocytes integrate apoptotic cell signals to mediate efferocytosis.
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Affiliation(s)
- Qian Zheng
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
| | - Ning Gao
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
| | - Qiling Sun
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
| | - Xiaowen Li
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
| | - Yanzhe Wang
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
| | - Hui Xiao
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
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5
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Ji Y, Ward LA, Hawkins CJ. Reconstitution of Human Necrosome Interactions in Saccharomyces cerevisiae. Biomolecules 2021; 11:biom11020153. [PMID: 33503908 PMCID: PMC7911209 DOI: 10.3390/biom11020153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/20/2021] [Accepted: 01/20/2021] [Indexed: 11/25/2022] Open
Abstract
The necrosome is a large-molecular-weight complex in which the terminal effector of the necroptotic pathway, Mixed Lineage Kinase Domain-Like protein (MLKL), is activated to induce necroptotic cell death. The precise mechanism of MLKL activation by the upstream kinase, Receptor Interacting Serine/Threonine Protein Kinase 3 (RIPK3) and the role of Receptor Interacting Serine/Threonine Protein Kinase 1 (RIPK1) in mediating MLKL activation remain incompletely understood. Here, we reconstituted human necrosome interactions in yeast by inducible expression of these necrosome effectors. Functional interactions were reflected by the detection of phosphorylated MLKL, plasma membrane permeabilization, and reduced proliferative potential. Following overexpression of human necrosome effectors in yeast, MLKL aggregated in the periphery of the cell, permeabilized the plasma membrane and compromised clonogenic potential. RIPK1 had little impact on RIPK3/MLKL-mediated yeast lethality; however, it exacerbated the toxicity provoked by co-expression of MLKL with a RIPK3 variant bearing a mutated RHIM-domain. Small molecule necroptotic inhibitors necrostatin-1 and TC13172, and viral inhibitors M45 (residues 1–90) and BAV_Rmil, abated the yeast toxicity triggered by the reconstituted necrosome. This yeast model provides a convenient tool to study necrosome protein interactions and to screen for and characterize potential necroptotic inhibitors.
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Suraweera CD, Anasir MI, Chugh S, Javorsky A, Impey RE, Hasan Zadeh M, Soares da Costa TP, Hinds MG, Kvansakul M. Structural insight into tanapoxvirus-mediated inhibition of apoptosis. FEBS J 2020; 287:3733-3750. [PMID: 32412687 DOI: 10.1111/febs.15365] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/26/2020] [Accepted: 05/12/2020] [Indexed: 01/07/2023]
Abstract
Premature programmed cell death or apoptosis of cells is a strategy utilized by multicellular organisms to counter microbial threats. Tanapoxvirus (TANV) is a large double-stranded DNA virus belonging to the poxviridae that causes mild monkeypox-like infections in humans and primates. TANV encodes for a putative apoptosis inhibitory protein 16L. We show that TANV16L is able to bind to a range of peptides spanning the BH3 motif of human proapoptotic Bcl-2 proteins and is able to counter growth arrest of yeast induced by human Bak and Bax. We then determined the crystal structures of TANV16L bound to three identified interactors, Bax, Bim and Puma BH3. TANV16L adopts a globular Bcl-2 fold comprising 7 α-helices and utilizes the canonical Bcl-2 binding groove to engage proapoptotic host cell Bcl-2 proteins. Unexpectedly, TANV16L is able to adopt both a monomeric and a domain-swapped dimeric topology where the α1 helix from one protomer is swapped into a neighbouring unit. Despite adopting two different oligomeric forms, the canonical ligand binding groove in TANV16L remains unchanged from monomer to domain-swapped dimer. Our results provide a structural and mechanistic basis for tanapoxvirus-mediated inhibition of host cell apoptosis and reveal the capacity of Bcl-2 proteins to adopt differential oligomeric states whilst maintaining the canonical ligand binding groove in an unchanged state. DATABASE: Structural data are available in the Protein Data Bank (PDB) under the accession numbers 6TPQ, 6TQQ and 6TRR.
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Affiliation(s)
- Chathura D Suraweera
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Mohd Ishtiaq Anasir
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Srishti Chugh
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Airah Javorsky
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Rachael E Impey
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Mohammad Hasan Zadeh
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Tatiana P Soares da Costa
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
| | - Mark G Hinds
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Australia
| | - Marc Kvansakul
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
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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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8
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Seong KM, Coates BS, Sun W, Clark JM, Pittendrigh BR. Changes in Neuronal Signaling and Cell Stress Response Pathways are Associated with a Multigenic Response of Drosophila melanogaster to DDT Selection. Genome Biol Evol 2018; 9:3356-3372. [PMID: 29211847 PMCID: PMC5737697 DOI: 10.1093/gbe/evx252] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2017] [Indexed: 12/11/2022] Open
Abstract
The adaptation of insect populations to insecticidal control is a continual threat to human health and sustainable agricultural practices, but many complex genomic mechanisms involved in this adaption remain poorly understood. This study applied a systems approach to investigate the interconnections between structural and functional variance in response to dichlorodiphenyltrichloroethane (DDT) within the Drosophila melanogaster strain 91-R. Directional selection in 6 selective sweeps coincided with constitutive gene expression differences in DDT resistant flies, including the most highly upregulated transcript, Unc-115 b, which plays a central role in axon guidance, and the most highly downregulated transcript, the angiopoietin-like CG31832, which is involved in directing vascular branching and dendrite outgrowth but likely may be under trans-regulatory control. Direct functions and protein–protein interactions mediated by differentially expressed transcripts control changes in cell migration, signal transduction, and gene regulatory cascades that impact the nervous system. Although changes to cellular stress response pathways involve 8 different cytochrome P450s, stress response, and apoptosis is controlled by a multifacetted regulatory mechanism. These data demonstrate that DDT selection in 91-R may have resulted in genome-wide adaptations that impacts genetic and signal transduction pathways that converge to modify stress response, cell survival, and neurological functions. This study implicates the involvement of a multigenic mechanism in the adaptation to a chemical insecticide, which impact interconnected regulatory cascades. We propose that DDT selection within 91-R might act systemically, wherein pathway interactions function to reinforce the epistatic effects of individual adaptive changes on an additive or nonadditive basis.
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Affiliation(s)
- Keon Mook Seong
- Department of Entomology, Michigan State University, East Lansing, Michigan, USA
| | - Brad S Coates
- Corn Insects & Crop Genetics Research Unit, USDA-ARS, Iowa State University, Ames, Iowa, USA
| | - Weilin Sun
- Department of Entomology, Michigan State University, East Lansing, Michigan, USA
| | - John M Clark
- Department of Veterinary & Animal Science, University of Massachusetts, Amherst, Massachusetts, USA
| | - Barry R Pittendrigh
- Department of Entomology, Michigan State University, East Lansing, Michigan, USA
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9
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Bushnell HL, Feiler CE, Ketosugbo KF, Hellerman MB, Nazzaro VL, Johnson RI. JNK is antagonized to ensure the correct number of interommatidial cells pattern the Drosophila retina. Dev Biol 2018; 433:94-107. [PMID: 29133184 PMCID: PMC6010229 DOI: 10.1016/j.ydbio.2017.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/29/2017] [Accepted: 11/04/2017] [Indexed: 11/25/2022]
Abstract
Apoptosis is crucial during the morphogenesis of most organs and tissues, and is utilized for tissues to achieve their proper size, shape and patterning. Many signaling pathways contribute to the precise regulation of apoptosis. Here we show that Jun N-terminal Kinase (JNK) activity contributes to the coordinated removal of interommatidial cells via apoptosis in the Drosophila pupal retina. This is consistent with previous findings that JNK activity promotes apoptosis in other epithelia. However, we found that JNK activity is repressed by Cindr (the CIN85 and CD2AP ortholog) in order to promote cell survival. Reducing the amount of Cindr resulted in ectopic cell death. Increased expression of the Drosophila JNK basket in the setting of reduced cindr expression was found to result in even more severe apoptosis, whilst ectopic death was found to be reduced if retinas were heterozygous for basket. Hence Cindr is required to properly restrict JNK-mediated apoptosis in the pupal eye, resulting in the correct number of interommatidial cells. A lack of precise control over developmental apoptosis can lead to improper tissue morphogenesis.
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Affiliation(s)
- Henry L Bushnell
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT, USA
| | - Christina E Feiler
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT, USA
| | - Kwami F Ketosugbo
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT, USA
| | - Mark B Hellerman
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT, USA
| | - Valerie L Nazzaro
- Quantitative Analysis Center, Wesleyan University, 222 Church Street, Middletown, CT, USA
| | - Ruth I Johnson
- Biology Department, Wesleyan University, 52 Lawn Avenue, Middletown, CT, USA.
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10
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Abstract
This chapter describes techniques for characterizing metazoan apoptotic pathways using Saccharomyces cerevisiae. Active forms of the major apoptotic effectors-caspases, Bax and Bak-are all lethal to yeast. Using this lethality as a readout of caspase/Bax/Bak activity, proteins and small molecules that directly or indirectly regulate the activity of these effectors can be investigated in yeast, and apoptotic inhibitors can be identified using functional yeast-based screens. Caspase activity can also be monitored in yeast by cleavage-dependent liberation of a transcription factor from the plasma membrane, enabling it to activate the lacZ reporter gene. This system can be used to define the sequences that can be efficiently cleaved by particular caspases.
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Wang Z, Xia X, Yang X, Zhang X, Liu Y, Wu D, Fang Y, Liu Y, Xu J, Qiu Y, Zhou X. A picorna-like virus suppresses the N-end rule pathway to inhibit apoptosis. eLife 2017; 6:30590. [PMID: 29231806 PMCID: PMC5739542 DOI: 10.7554/elife.30590] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 12/11/2017] [Indexed: 12/21/2022] Open
Abstract
The N-end rule pathway is an evolutionarily conserved proteolytic system that degrades proteins containing N-terminal degradation signals called N-degrons, and has emerged as a key regulator of various processes. Viruses manipulate diverse host pathways to facilitate viral replication and evade antiviral defenses. However, it remains unclear if viral infection has any impact on the N-end rule pathway. Here, using a picorna-like virus as a model, we found that viral infection promoted the accumulation of caspase-cleaved Drosophila inhibitor of apoptosis 1 (DIAP1) by inducing the degradation of N-terminal amidohydrolase 1 (NTAN1), a key N-end rule component that identifies N-degron to initiate the process. The virus-induced NTAN1 degradation is independent of polyubiquitylation but dependent on proteasome. Furthermore, the virus-induced N-end rule pathway suppression inhibits apoptosis and benefits viral replication. Thus, our findings demonstrate that a virus can suppress the N-end rule pathway, and uncover a new mechanism for virus to evade apoptosis.
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Affiliation(s)
- Zhaowei Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xiaoling Xia
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology & School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xueli Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xueyi Zhang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yongxiang Liu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Di Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yuan Fang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yujie Liu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Jiuyue Xu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Yang Qiu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Xi Zhou
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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12
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Vaccinia Virus Encodes a Novel Inhibitor of Apoptosis That Associates with the Apoptosome. J Virol 2017; 91:JVI.01385-17. [PMID: 28904196 DOI: 10.1128/jvi.01385-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/08/2017] [Indexed: 12/29/2022] Open
Abstract
Apoptosis is an important antiviral host defense mechanism. Here we report the identification of a novel apoptosis inhibitor encoded by the vaccinia virus (VACV) M1L gene. M1L is absent in the attenuated modified vaccinia virus Ankara (MVA) strain of VACV, a strain that stimulates apoptosis in several types of immune cells. M1 expression increased the viability of MVA-infected THP-1 and Jurkat cells and reduced several biochemical hallmarks of apoptosis, such as PARP-1 and procaspase-3 cleavage. Furthermore, ectopic M1L expression decreased staurosporine-induced (intrinsic) apoptosis in HeLa cells. We then identified the molecular basis for M1 inhibitory function. M1 allowed mitochondrial depolarization but blocked procaspase-9 processing, suggesting that M1 targeted the apoptosome. In support of this model, we found that M1 promoted survival in Saccharomyces cerevisiae overexpressing human Apaf-1 and procaspase-9, critical components of the apoptosome, or overexpressing only conformationally active caspase-9. In mammalian cells, M1 coimmunoprecipitated with Apaf-1-procaspase-9 complexes. The current model is that M1 associates with and allows the formation of the apoptosome but prevents apoptotic functions of the apoptosome. The M1 protein features 14 predicted ankyrin (ANK) repeat domains, and M1 is the first ANK-containing protein reported to use this inhibitory strategy. Since ANK-containing proteins are encoded by many large DNA viruses and found in all domains of life, studies of M1 may lead to a better understanding of the roles of ANK proteins in virus-host interactions.IMPORTANCE Apoptosis selectively eliminates dangerous cells such as virus-infected cells. Poxviruses express apoptosis antagonists to neutralize this antiviral host defense. The vaccinia virus (VACV) M1 ankyrin (ANK) protein, a protein with no previously ascribed function, inhibits apoptosis. M1 interacts with the apoptosome and prevents procaspase-9 processing as well as downstream procaspase-3 cleavage in several cell types and under multiple conditions. M1 is the first poxviral protein reported to associate with and prevent the function of the apoptosome, giving a more detailed picture of the threats VACV encounters during infection. Dysregulation of apoptosis is associated with several human diseases. One potential treatment of apoptosis-related diseases is through the use of designed ANK repeat proteins (DARPins), similar to M1, as caspase inhibitors. Thus, the study of the novel antiapoptosis effects of M1 via apoptosome association will be helpful for understanding how to control apoptosis using either natural or synthetic molecules.
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13
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Tran HT, Fransen M, Dimitrakopoulou D, Van Imschoot G, Willemarck N, Vleminckx K. Caspase-9 has a nonapoptotic function in Xenopus embryonic primitive blood formation. J Cell Sci 2017; 130:2371-2381. [PMID: 28576973 DOI: 10.1242/jcs.186411] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 05/30/2017] [Indexed: 12/29/2022] Open
Abstract
Caspases constitute a family of cysteine proteases centrally involved in programmed cell death, which is an integral part of normal embryonic and fetal development. However, it has become clear that specific caspases also have functions independent of cell death. In order to identify novel apoptotic and nonapoptotic developmental caspase functions, we designed and transgenically integrated novel fluorescent caspase reporter constructs in developing Xenopus embryos and tadpoles. This model organism has an external development, allowing direct and continuous monitoring. These studies uncovered a nonapoptotic role for the initiator caspase-9 in primitive blood formation. Functional experiments further corroborated that caspase-9, but possibly not the executioners caspase-3 and caspase-7, are required for primitive erythropoiesis in the early embryo. These data reveal a novel nonapoptotic function for the initiator caspase-9 and, for the first time, implicate nonapoptotic caspase activity in primitive blood formation.
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Affiliation(s)
- Hong Thi Tran
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium
| | - Mathias Fransen
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium
| | | | - Griet Van Imschoot
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium.,VIB-UGent Center for Inflammation Research, B-9052 Ghent, Belgium
| | - Nicolas Willemarck
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium
| | - Kris Vleminckx
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium
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14
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Caria S, Marshall B, Burton RL, Campbell S, Pantaki-Eimany D, Hawkins CJ, Barry M, Kvansakul M. The N Terminus of the Vaccinia Virus Protein F1L Is an Intrinsically Unstructured Region That Is Not Involved in Apoptosis Regulation. J Biol Chem 2016; 291:14600-8. [PMID: 27151220 DOI: 10.1074/jbc.m116.726851] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Indexed: 12/21/2022] Open
Abstract
Subversion of host cell apoptotic responses is a prominent feature of viral immune evasion strategies to prevent premature clearance of infected cells. Numerous poxviruses encode structural and functional homologs of the Bcl-2 family of proteins, and vaccinia virus harbors antiapoptotic F1L that potently inhibits the mitochondrial apoptotic checkpoint. Recently F1L has been assigned a caspase-9 inhibitory function attributed to an N-terminal α helical region of F1L spanning residues 1-15 (1) preceding the domain-swapped Bcl-2-like domains. Using a reconstituted caspase inhibition assay in yeast we found that unlike AcP35, a well characterized caspase-9 inhibitor from the insect virus Autographa californica multiple nucleopolyhedrovirus, F1L does not prevent caspase-9-mediated yeast cell death. Furthermore, we found that deletion of the F1L N-terminal region does not impede F1L antiapoptotic activity in the context of a viral infection. Solution analysis of the F1L N-terminal regions using small angle x-ray scattering indicates that the region of F1L spanning residues 1-50 located N-terminally from the Bcl-2 fold is an intrinsically unstructured region. We conclude that the N terminus of F1L is not involved in apoptosis inhibition and may act as a regulatory element in other signaling pathways in a manner reminiscent of other unstructured regulatory elements commonly found in mammalian prosurvival Bcl-2 members including Bcl-xL and Mcl-1.
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Affiliation(s)
- Sofia Caria
- From the La Trobe Institute for Molecular Science, Department of Biochemistry and Genetics, La Trobe University, Victoria 3086, Australia and
| | - Bevan Marshall
- From the La Trobe Institute for Molecular Science, Department of Biochemistry and Genetics, La Trobe University, Victoria 3086, Australia and
| | - Robyn-Lee Burton
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Stephanie Campbell
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Delara Pantaki-Eimany
- From the La Trobe Institute for Molecular Science, Department of Biochemistry and Genetics, La Trobe University, Victoria 3086, Australia and
| | - Christine J Hawkins
- From the La Trobe Institute for Molecular Science, Department of Biochemistry and Genetics, La Trobe University, Victoria 3086, Australia and
| | - Michele Barry
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Marc Kvansakul
- From the La Trobe Institute for Molecular Science, Department of Biochemistry and Genetics, La Trobe University, Victoria 3086, Australia and
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15
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Bhogal B, Plaza-Jennings A, Gavis ER. Nanos-mediated repression of hid protects larval sensory neurons after a global switch in sensitivity to apoptotic signals. Development 2016; 143:2147-59. [PMID: 27256879 DOI: 10.1242/dev.132415] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 04/11/2016] [Indexed: 01/05/2023]
Abstract
Dendritic arbor morphology is a key determinant of neuronal function. Once established, dendrite branching patterns must be maintained as the animal develops to ensure receptive field coverage. The translational repressors Nanos (Nos) and Pumilio (Pum) are required to maintain dendrite growth and branching of Drosophila larval class IV dendritic arborization (da) neurons, but their specific regulatory role remains unknown. We show that Nos-Pum-mediated repression of the pro-apoptotic gene head involution defective (hid) is required to maintain a balance of dendritic growth and retraction in class IV da neurons and that upregulation of hid results in decreased branching because of an increase in caspase activity. The temporal requirement for nos correlates with an ecdysone-triggered switch in sensitivity to apoptotic stimuli that occurs during the mid-L3 transition. We find that hid is required during pupariation for caspase-dependent pruning of class IV da neurons and that Nos and Pum delay pruning. Together, these results suggest that Nos and Pum provide a crucial neuroprotective regulatory layer to ensure that neurons behave appropriately in response to developmental cues.
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Affiliation(s)
- Balpreet Bhogal
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | | | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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16
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Unsain N, Barker PA. New Views on the Misconstrued: Executioner Caspases and Their Diverse Non-apoptotic Roles. Neuron 2016; 88:461-74. [PMID: 26539888 DOI: 10.1016/j.neuron.2015.08.029] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Initially characterized for their roles in apoptosis, executioner caspases have emerged as important regulators of an array of cellular activities. This is especially true in the nervous system, where sublethal caspase activity has been implicated in axonal pathfinding and branching, axonal degeneration, dendrite pruning, regeneration, long-term depression, and metaplasticity. Here we examine the roles of sublethal executioner caspase activity in nervous system development and maintenance, consider the mechanisms that locally activate and restrain these potential killers, and discuss how their activity be subverted in neurodegenerative disease.
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Affiliation(s)
- Nicolas Unsain
- Laboratorio de Neurobiología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, Instituto Nacional de Investigación Médica Córdoba-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba, Friuli 2434, Córdoba (5016), Argentina
| | - Philip A Barker
- Irving K. Barber School of Arts and Sciences, University of British Columbia, Kelowna, BC V1V 1V7, Canada.
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17
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Apoptotic Caspases in Promoting Cancer: Implications from Their Roles in Development and Tissue Homeostasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 930:89-112. [PMID: 27558818 DOI: 10.1007/978-3-319-39406-0_4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Apoptosis, a major form of programmed cell death, is an important mechanism to remove extra or unwanted cells during development. In tissue homeostasis apoptosis also acts as a monitoring machinery to eliminate damaged cells in response to environmental stresses. During these processes, caspases, a group of proteases, have been well defined as key drivers of cell death. However, a wealth of evidence is emerging which supports the existence of many other non-apoptotic functions of these caspases, which are essential not only in proper organism development but also in tissue homeostasis and post-injury recovery. In particular, apoptotic caspases in stress-induced dying cells can activate mitogenic signals leading to proliferation of neighbouring cells, a phenomenon termed apoptosis-induced proliferation. Apparently, such non-apoptotic functions of caspases need to be controlled and restrained in a context-dependent manner during development to prevent their detrimental effects. Intriguingly, accumulating studies suggest that cancer cells are able to utilise these functions of caspases to their advantage to enable their survival, proliferation and metastasis in order to grow and progress. This book chapter will review non-apoptotic functions of the caspases in development and tissue homeostasis with focus on how these cellular processes can be hijacked by cancer cells and contribute to tumourigenesis.
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18
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Abstract
Cell death and inflammation are ancient processes of fundamental biological importance in both normal physiology and human disease pathologies. The recent observation that apoptosis regulatory components have dual roles in cell death and inflammation suggests that these proteins function, not primarily to kill, but to coordinate tissue repair and remodeling. This perspective unifies cell death components as positive regulators of tissue repair that replaces malfunctioning or damaged tissues and enhances the resilience of epithelia to insult. It is now recognized that cells that die by apoptosis do not do so silently, but release a variety of paracrine signals to communicate with their cellular environment to ensure tissue regeneration, and wound healing. Moreover, inflammatory signaling pathways, such as those emanating from the TNF receptor or Toll-related receptors, take part in cell competition to eliminate developmentally aberrant clones. Ubiquitylation has emerged as crucial mediator of signal transduction in cell death and inflammation. Here, we focus on recent advances on ubiquitin-mediated regulation of cell death and inflammation, and how this is used to regulate the defense of homeostasis.
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19
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Abstract
Inhibitors of apoptosis (IAPs) family of genes encode baculovirus IAP-repeat domain-containing proteins with antiapoptotic function. These proteins also contain RING or UBC domains and act by binding to major proapoptotic factors and ubiquitylating them. High levels of IAPs inhibit caspase-mediated apoptosis. For these cells to undergo apoptosis, IAP function must be neutralized by IAP-antagonists. Mammalian IAP knockouts do not exhibit obvious developmental phenotypes, but the cells are more sensitized to apoptosis in response to injury. Loss of the mammalian IAP-antagonist ARTS results in reduced stem cell apoptosis. In addition to the antiapoptotic properties, IAPs regulate the innate immune response, and the loss of IAP function in humans is associated with immunodeficiency. The roles of IAPs in Drosophila apoptosis regulation are more apparent, where the loss of IAP1, or the expression of IAP-antagonists in Drosophila cells, is sufficient to trigger apoptosis. In this organism, apoptosis as a fate is conferred by the transcriptional induction of the IAP-antagonists. Many signaling pathways often converge on shared enhancer regions of IAP-antagonists. Cell death sensitivity is further regulated by posttranscriptional mechanisms, including those regulated by kinases, miRs, and ubiquitin ligases. These mechanisms are employed to eliminate damaged or virus-infected cells, limit neuroblast (neural stem cell) numbers, generate neuronal diversity, and sculpt tissue morphogenesis.
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Affiliation(s)
- Deepika Vasudevan
- Department of Cell Biology, New York University School of Medicine, New York, New York, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, New York, USA.
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20
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Zhang B, Xu Z, Zhang Y, Shao X, Xu X, Cheng J, Li Z. Fipronil induces apoptosis through caspase-dependent mitochondrial pathways in Drosophila S2 cells. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2015; 119:81-89. [PMID: 25868821 DOI: 10.1016/j.pestbp.2015.01.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 01/29/2015] [Accepted: 01/29/2015] [Indexed: 06/04/2023]
Abstract
Fipronil is the first phenylpyrazole insecticide widely used in controlling pests, including pyrethroid, organophosphate and carbamate insecticides. It is generally accepted that fipronil elicits neurotoxicity via interactions with GABA and glutamate receptors, although alternative mechanisms have recently been proposed. This study evaluates the genotoxicity of fipronil and its likely mode of action in Drosophila S2 cells, as an in vitro model. Fipronil administrated the concentration- and time-dependent S2 cell proliferation. Intracellular biochemical assays showed that fipronil-induced S2 cell apoptosis coincided with a decrease in the mitochondrial membrane potential and an increase reactive oxygen species generation, a significant decrease of Bcl-2 and DIAP1, and a marked augmentation of Cyt c and caspase-3. Because caspase-3 is the major executioner caspase downstream of caspase-9 in Drosophila, enzyme activity assays were used to determine the activities of caspase-3 and caspase-9. Our results indicated that fipronil effectively induced apoptosis in Drosophila S2 cells through caspase-dependent mitochondrial pathways.
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Affiliation(s)
- Baoyan Zhang
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Zhiping Xu
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
| | - Yixi Zhang
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Xusheng Shao
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Xiaoyong Xu
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Jiaogao Cheng
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Zhong Li
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
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21
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Chen YS, Qiu XB. Ubiquitin at the crossroad of cell death and survival. CHINESE JOURNAL OF CANCER 2013; 32:640-7. [PMID: 23816559 PMCID: PMC3870847 DOI: 10.5732/cjc.012.10283] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 02/20/2013] [Accepted: 03/15/2013] [Indexed: 12/19/2022]
Abstract
Ubiquitination is crucial for cellular processes, such as protein degradation, apoptosis, autophagy, and cell cycle progression. Dysregulation of the ubiquitination network accounts for the development of numerous diseases, including cancer. Thus, targeting ubiquitination is a promising strategy in cancer therapy. Both apoptosis and autophagy are involved in tumorigenesis and response to cancer therapy. Although both are categorized as types of cell death, autophagy is generally considered to have protective functions, including protecting cells from apoptosis under certain cellular stress conditions. This review highlights recent advances in understanding the regulation of apoptosis and autophagy by ubiquitination.
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Affiliation(s)
- Yu-Shan Chen
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, and College of Life Sciences, Beijing Normal University, Beijing 100875, P. R. China.
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22
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Beaumont TE, Shekhar TM, Kaur L, Pantaki-Eimany D, Kvansakul M, Hawkins CJ. Yeast techniques for modeling drugs targeting Bcl-2 and caspase family members. Cell Death Dis 2013; 4:e619. [PMID: 23640461 PMCID: PMC3674352 DOI: 10.1038/cddis.2013.143] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Development of drugs targeting Bcl-2 relatives and caspases, for treating diseases including cancer and inflammatory disorders, often involves measuring interactions with recombinant target molecules, and/or monitoring cancer cell killing in vitro. Here, we present yeast-based methods for evaluating drug-mediated inhibition of Bcl-2 relatives or caspases. Active Bax and caspases kill Saccharomyces cerevisiae, and pro-survival Bcl-2 proteins can inhibit Bax-induced yeast death. By measuring the growth or adenosine triphosphate content of transformants co-expressing Bax with pro-survival Bcl-2 relatives, we found that the Bcl-2 antagonist drugs ABT-737 or ABT-263 abolished Bcl-2 or Bcl-xL function and reduced Bcl-w activity, but failed to inhibit Mcl-1, A1 or the poxvirus orthologs DPV022 and SPPV14. Using this technique, we also demonstrated that adenoviral E1B19K was resistant to these agents. The caspase inhibitor Q-VD-OPh suppressed yeast death induced by caspases 1 and 3. Yeast engineered to express human apoptotic regulators enable simple, automatable assessment of the activity and specificity of candidate drugs targeting Bcl-2 relatives or caspases.
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Affiliation(s)
- T E Beaumont
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia
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23
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Ectopic antenna induction by overexpression of CG17836/Xrp1 encoding an AT-hook DNA binding motif protein in Drosophila. Biosci Biotechnol Biochem 2013; 77:339-44. [PMID: 23391928 DOI: 10.1271/bbb.120756] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Drosophila imaginal discs are an excellent model system for studies of developmental plasticity. In imaginal discs, most cells adhere strictly to their specific identity, but some cells undergo transdetermination, a process wherein the determined identity switches to another disc-specific identity. In this study, we performed gain-of-function screening and identified a gene, CG17836/Xrp1, that induces ectopic antennae in the eye field upon overexpression at the early eye disc stage. An essential factor in the distalization process, Distalles, and its upstream regulators Wingless, Hedgehog, and Decapentaplegic, are ectopically induced by CG17836/Xrp1 overexpression in eye discs, and this provides molecular evidence of the formation of ectopic antennae. Further, forced expression of CG17836/Xrp1 induced severe cell-proliferation defects. These findings suggest that CG17836/Xrp1 is involved in the regulation of cell proliferation in eye discs and affects disc identity specification.
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24
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Okamoto T, Campbell S, Mehta N, Thibault J, Colman PM, Barry M, Huang DCS, Kvansakul M. Sheeppox virus SPPV14 encodes a Bcl-2-like cell death inhibitor that counters a distinct set of mammalian proapoptotic proteins. J Virol 2012; 86:11501-11. [PMID: 22896610 PMCID: PMC3486325 DOI: 10.1128/jvi.01115-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/24/2012] [Indexed: 12/16/2022] Open
Abstract
Many viruses express inhibitors of programmed cell death (apoptosis), thereby countering host defenses that would otherwise rapidly clear infected cells. To counter this, viruses such as adenoviruses and herpesviruses express recognizable homologs of the mammalian prosurvival protein Bcl-2. In contrast, the majority of poxviruses lack viral Bcl-2 (vBcl-2) homologs that are readily identified by sequence similarities. One such virus, myxoma virus, which is the causative agent of myxomatosis, expresses a virulence factor that is a potent inhibitor of apoptosis. In spite of the scant sequence similarity to Bcl-2, myxoma virus M11L adopts an almost identical 3-dimensional fold. We used M11L as bait in a sequence similarity search for other Bcl-2-like proteins and identified six putative vBcl-2 proteins from poxviruses. Some are potent inhibitors of apoptosis, in particular sheeppox virus SPPV14, which inhibited cell death induced by multiple agents. Importantly, SPPV14 compensated for the loss of antiapoptotic F1L in vaccinia virus and acts to directly counter the cell death mediators Bax and Bak. SPPV14 also engages a unique subset of the death-promoting BH3-only ligands, including Bim, Puma, Bmf, and Hrk. This suggests that SPPV14 may have been selected for specific biological roles as a virulence factor for sheeppox virus.
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Affiliation(s)
- Toru Okamoto
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Stephanie Campbell
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Ninad Mehta
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - John Thibault
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Peter M. Colman
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Michele Barry
- Li Ka Shing Institute for Virology, Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - David C. S. Huang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Marc Kvansakul
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
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25
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Khoa DB, Takeda M. Expression analysis of inhibitor of apoptosis and related caspases in the midgut and silk gland of the greater wax moth, Galleria mellonella, during metamorphosis and under starvation. Gene 2012; 510:133-41. [PMID: 22975212 DOI: 10.1016/j.gene.2012.08.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 08/09/2012] [Accepted: 08/24/2012] [Indexed: 11/17/2022]
Abstract
We cloned a cDNA encoding inhibitor of apoptosis (IAP) from the greater wax moth, Galleria mellonella. The deduced amino acid sequence showed that GmIAP contains two baculoviral IAP repeat (BIR) motifs, followed by a RING finger. The sequence comparison showed that GmIAP had high homology to lepidopteran IAPs and baculoviral IAPs, as well as dipteran IAPs. GmIAP transcript and its protein appeared in both the midgut and the silk gland during metamorphosis and starvation where cell death was detected by TUNEL test. IAP, and capases-1, -3, -4 and -6 appeared as at least two peaks in the midgut and silk gland during metamorphosis. Caspase-1 transcript appeared at the highest level among caspases, while caspase-3 and caspase-6 seemed to be the most relevant caspases to IAP during metamorphosis suggesting that IAP and caspases may be involved in a core apoptosis pathway in the wax moth as in flies and mosquitoes.
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Affiliation(s)
- Dao Bach Khoa
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe-shi 657-8501 Japan
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26
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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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27
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Pereira C, Coutinho I, Soares J, Bessa C, Leão M, Saraiva L. New insights into cancer-related proteins provided by the yeast model. FEBS J 2012; 279:697-712. [PMID: 22239976 DOI: 10.1111/j.1742-4658.2012.08477.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cancer is a devastating disease with a profound impact on society. In recent years, yeast has provided a valuable contribution with respect to uncovering the molecular mechanisms underlying this disease, allowing the identification of new targets and novel therapeutic opportunities. Indeed, several attributes make yeast an ideal model system for the study of human diseases. It combines a high level of conservation between its cellular processes and those of mammalian cells, with advantages such as a short generation time, ease of genetic manipulation and a wealth of experimental tools for genome- and proteome-wide analyses. Additionally, the heterologous expression of disease-causing proteins in yeast has been successfully used to gain an understanding of the functions of these proteins and also to provide clues about the mechanisms of disease progression. Yeast research performed in recent years has demonstrated the tremendous potential of this model system, especially with the validation of findings obtained with yeast in more physiologically relevant models. The present review covers the major aspects of the most recent developments in the yeast research area with respect to cancer. It summarizes our current knowledge on yeast as a cellular model for investigating the molecular mechanisms of action of the major cancer-related proteins that, even without yeast orthologues, still recapitulate in yeast some of the key aspects of this cellular pathology. Moreover, the most recent contributions of yeast genetics and high-throughput screening technologies that aim to identify some of the potential causes underpinning this disorder, as well as discover new therapeutic agents, are discussed.
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Affiliation(s)
- Clara Pereira
- REQUIMTE, Department of Biological Sciences, Laboratory of Microbiology, University of Porto, Portugal
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28
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Brand IL, Green MM, Civciristov S, Pantaki-Eimany D, George C, Gort TR, Huang N, Clem RJ, Hawkins CJ. Functional and biochemical characterization of the baculovirus caspase inhibitor MaviP35. Cell Death Dis 2011; 2:e242. [PMID: 22170098 PMCID: PMC3252740 DOI: 10.1038/cddis.2011.127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Many viruses express proteins which prevent the host cell death that their infection would otherwise provoke. Some insect viruses suppress host apoptosis through the expression of caspase inhibitors belonging to the P35 superfamily. Although a number of P35 relatives have been identified, Autographa californica (Ac) P35 and Spodoptera littoralis (Spli) P49 have been the most extensively characterized. AcP35 was found to inhibit caspases via a suicide substrate mechanism: the caspase cleaves AcP35 within its ‘reactive site loop' then becomes trapped, irreversibly bound to the cleaved inhibitor. The Maruca vitrata multiple nucleopolyhedrovirus encodes a P35 family member (MaviP35) that exhibits 81% identity to AcP35. We found that this relative shared with AcP35 the ability to inhibit mammalian and insect cell death. Caspase-mediated cleavage within the MaviP35 reactive site loop occurred at a sequence distinct from that in AcP35, and the inhibitory profiles of the two P35 relatives differed. MaviP35 potently inhibited human caspases 2 and 3, DCP-1, DRICE and CED-3 in vitro, but (in contrast to AcP35) only weakly suppressed the proteolytic activity of the initiator human caspases 8, 9 and 10. Although MaviP35 inhibited the AcP35-resistant caspase DRONC in yeast, and was sensitive to cleavage by DRONC in vitro, MaviP35 failed to inhibit the proteolytic activity of bacterially produced DRONC in vitro.
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Affiliation(s)
- I L Brand
- Department of Biochemistry, La Trobe University, Bundoora, Victoria, Australia
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Ma X, Huang J, Yang L, Yang Y, Li W, Xue L. NOPO modulates Egr-induced JNK-independent cell death in Drosophila. Cell Res 2011; 22:425-31. [PMID: 21844890 DOI: 10.1038/cr.2011.135] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Tumor necrosis factor (TNF) family ligands play essential roles in regulating a variety of cellular processes including proliferation, differentiation and survival. Expression of Drosophila TNF ortholog Eiger (Egr) induces JNK-dependent cell death, while the roles of caspases in this process remain elusive. To further delineate the Egr-triggered cell death pathway, we performed a genetic screen to identify dominant modifiers of the Egr-induced cell death phenotype. Here we report that Egr elicits a caspase-mediated cell death pathway independent of JNK signaling. Furthermore, we show NOPO, the Drosophila ortholog of TRIP (TRAF interacting protein) encoding an E3 ubiquitin ligase, modulates Egr-induced Caspase-mediated cell death through transcriptional activation of pro-apoptotic genes reaper and hid. Finally, we found Bendless and dUEV1a, an ubiquitin-conjugating E2 enzyme complex, regulates NOPO-triggered cell death. Our results indicate that the Ben-dUEV1a complex constitutes a molecular switch that bifurcates the Egr-induced cell death signaling into two pathways mediated by JNK and caspases respectively.
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Affiliation(s)
- Xianjue Ma
- Shanghai Key Laboratory for Signaling and Diseases, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, China
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Czabotar PE, Lee EF, Thompson GV, Wardak AZ, Fairlie WD, Colman PM. Mutation to Bax beyond the BH3 domain disrupts interactions with pro-survival proteins and promotes apoptosis. J Biol Chem 2011; 286:7123-31. [PMID: 21199865 PMCID: PMC3044969 DOI: 10.1074/jbc.m110.161281] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 12/15/2010] [Indexed: 11/06/2022] Open
Abstract
Pro-survival members of the Bcl-2 family of proteins restrain the pro-apoptotic activity of Bax, either directly through interactions with Bax or indirectly by sequestration of activator BH3-only proteins, or both. Mutations in Bax that promote apoptosis can provide insight into how Bax is regulated. Here, we describe crystal structures of the pro-survival proteins Mcl-1 and Bcl-x(L) in complex with a 34-mer peptide from Bax that encompasses its BH3 domain. These structures reveal canonical interactions between four signature hydrophobic amino acids from the BaxBH3 domain and the BH3-binding groove of the pro-survival proteins. In both structures, Met-74 from the Bax peptide engages with the BH3-binding groove in a fifth hydrophobic interaction. Various Bax Met-74 mutants disrupt interactions between Bax and all pro-survival proteins, but these Bax mutants retain pro-apoptotic activity. Bax/Bak-deficient mouse embryonic fibroblast cells reconstituted with several Bax Met-74 mutants are more sensitive to the BH3 mimetic compound ABT-737 as compared with cells expressing wild-type Bax. Furthermore, the cells expressing Bax Met-74 mutants are less viable in colony assays even in the absence of an external apoptotic stimulus. These results support a model in which direct restraint of Bax by pro-survival Bcl-2 proteins is a barrier to apoptosis.
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Affiliation(s)
- Peter E. Czabotar
- From the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia and
| | - Erinna F. Lee
- From the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia and
| | - Geoff V. Thompson
- From the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia and
| | - Ahmad Z. Wardak
- From the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia and
| | - W. Douglas Fairlie
- From the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia and
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Peter M. Colman
- From the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia and
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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Induction of reaper ortholog mx in mosquito midgut cells following baculovirus infection. Cell Death Differ 2011; 18:1337-45. [PMID: 21331076 DOI: 10.1038/cdd.2011.8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Many vertebrate and insect viruses possess antiapoptotic genes that are required for their infectivity. This led to the hypothesis that apoptosis is an innate immunoresponse important for limiting virus infections. The role of apoptosis may be especially important in insect antiviral defense because of the lack of adaptive immunity. However, the cellular mechanism that elicits apoptosis in response to viral infection in insects has not been determined. Using an in vivo infection system with the mosquito baculovirus CuniNPV (Culex nigripalpus nucleopolyhedrovirus), we demonstrated that michelob_x (mx), the mosquito ortholog of Drosophila proapoptotic gene reaper, is specifically induced in larval midgut cells following viral infection. Interestingly, the dynamics of mx induction corresponds with the outcome of the infection. In the permissive mosquito C. quinquefasciatus, a slow induction of mx failed to induce prompt apoptosis, and the infected cells eventually undergo necrosis with heavy loads of encapsulated viruses. In contrast, in the refractory mosquito Aedes aegypti, a rapid induction of mx within 30 min p.i. is followed by apoptosis within 2-6 h p.i., suggesting a possible role for apoptosis in limiting viral infection. When the execution of apoptosis was delayed by caspase inhibitors, viral gene expression became detectable in the A. aegypti larvae.
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Structural basis for apoptosis inhibition by Epstein-Barr virus BHRF1. PLoS Pathog 2010; 6:e1001236. [PMID: 21203485 PMCID: PMC3009601 DOI: 10.1371/journal.ppat.1001236] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 11/22/2010] [Indexed: 01/19/2023] Open
Abstract
Epstein-Barr virus (EBV) is associated with human malignancies, especially those affecting the B cell compartment such as Burkitt lymphoma. The virally encoded homolog of the mammalian pro-survival protein Bcl-2, BHRF1 contributes to viral infectivity and lymphomagenesis. In addition to the pro-apoptotic BH3-only protein Bim, its key target in lymphoid cells, BHRF1 also binds a selective sub-set of pro-apoptotic proteins (Bid, Puma, Bak) expressed by host cells. A consequence of BHRF1 expression is marked resistance to a range of cytotoxic agents and in particular, we show that its expression renders a mouse model of Burkitt lymphoma untreatable. As current small organic antagonists of Bcl-2 do not target BHRF1, the structures of it in complex with Bim or Bak shown here will be useful to guide efforts to target BHRF1 in EBV-associated malignancies, which are usually associated with poor clinical outcomes. Altruistic suicide of infected host cells is a key defense mechanism to combat viral infection. To ensure their own survival and proliferation, certain viruses, including Epstein-Barr virus (EBV), have mechanisms to subvert apoptosis, including the expression of homologs of the mammalian pro-survival protein Bcl-2. EBV was first identified in association with Burkitt lymphoma and it is also linked to certain Hodgkin's lymphomas and nasopharyngeal carcinoma. Whereas increased expression of Bcl-2 promotes malignancies such as human follicular lymphoma, the precise role of the EBV encoded Bcl-2 homolog BHRF1 in EBV-associated malignancies is less well defined. BHRF1 is known to bind the pro-apoptotic BH3-only protein Bim, and here we demonstrate that it also binds other pro-apoptotic proteins (Bid, Puma, Bak) expressed by host cells. Crystal structures of BHRF1 with the BH3 regions of Bim and Bak illustrate these interactions in atomic detail. A consequence of BHRF1 expression is marked resistance to a range of cytotoxic agents, and we show that its expression renders a mouse model of Burkitt lymphoma untreatable. As current antagonists of Bcl-2 do not target BHRF1, our crystal structures will be useful to guide efforts to target BHRF1 in EBV-associated malignancies, which are usually associated with poor clinical outcomes.
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Abstract
Poxviruses encode numerous proteins that inhibit apoptosis, a form of cell death critical to the elimination of virally infected cells. Sequencing of the deerpox virus genome revealed DPV022, a protein that lacks obvious homology to cellular members of the Bcl-2 family but shares limited regions of amino acid identity with two unique poxviral inhibitors of apoptosis, M11L and F1L. Given the limited homology, we sought to determine whether DPV022 could inhibit apoptosis. Here we show that DPV022 localized to the mitochondria, where it inhibited apoptosis. We used a Saccharomyces cerevisiae model system to demonstrate that in the absence of all other Bcl-2 family proteins, DPV022 interacted directly with Bak and Bax. We confirmed the ability of DPV022 to interact with Bak and Bax by immunoprecipitation and showed that DPV022 prevented apoptosis induced by Bak and Bax overexpression. Moreover, we showed that DPV022 blocked apoptosis even when all the endogenous mammalian antiapoptotic proteins were neutralized by a combination of selective BH3 ligands. During virus infection, DPV022 interacted with endogenous Bak and Bax and prevented the conformational activation of both of them. Thus, we have characterized a novel poxviral inhibitor of apoptosis with intriguing amino acid differences from the well-studied proteins M11L and F1L.
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Abstract
The realization that alterations in inhibitor of apoptosis (IAP) proteins are found in many types of human cancer and are associated with chemoresistance, disease progression and poor prognosis, has sparked a worldwide frenzy in the development of small pharmacological inhibitors of IAPs. The development of such inhibitors has radically changed our knowledge of the signalling processes that are regulated by IAPs. Recent studies indicate that IAPs not only regulate caspases and apoptosis, but also modulate inflammatory signalling and immunity, mitogenic kinase signalling, proliferation and mitosis, as well as cell invasion and metastasis.
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Affiliation(s)
- Mads Gyrd-Hansen
- Biotech Research and Innovation Centre, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen DK2200, Denmark.
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Versatile assays for high throughput screening for activators or inhibitors of intracellular proteases and their cellular regulators. PLoS One 2009; 4:e7655. [PMID: 19876397 PMCID: PMC2764853 DOI: 10.1371/journal.pone.0007655] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Accepted: 08/06/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Intracellular proteases constitute a class of promising drug discovery targets. Methods for high throughput screening against these targets are generally limited to in vitro biochemical assays that can suffer many technical limitations, as well as failing to capture the biological context of proteases within the cellular pathways that lead to their activation. METHODS #ENTITYSTARTX00026; FINDINGS We describe here a versatile system for reconstituting protease activation networks in yeast and assaying the activity of these pathways using a cleavable transcription factor substrate in conjunction with reporter gene read-outs. The utility of these versatile assay components and their application for screening strategies was validated for all ten human Caspases, a family of intracellular proteases involved in cell death and inflammation, including implementation of assays for high throughput screening (HTS) of chemical libraries and functional screening of cDNA libraries. The versatility of the technology was also demonstrated for human autophagins, cysteine proteases involved in autophagy. CONCLUSIONS Altogether, the yeast-based systems described here for monitoring activity of ectopically expressed mammalian proteases provide a fascile platform for functional genomics and chemical library screening.
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Koto A, Kuranaga E, Miura M. Temporal regulation of Drosophila IAP1 determines caspase functions in sensory organ development. ACTA ACUST UNITED AC 2009; 187:219-31. [PMID: 19822670 PMCID: PMC2768825 DOI: 10.1083/jcb.200905110] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Caspase activation is regulated by the turnover of E3 ubiquitin ligase, DIAP1, and depends on cell type and maturity. The caspases comprise a family of cysteine proteases that function in various cellular processes, including apoptosis. However, how the balance is struck between the caspases’ role in cell death and their nonapoptotic functions is unclear. To address this issue, we monitored the protein turnover of an endogenous caspase inhibitor, Drosophila IAP1 (DIAP1). DIAP1 is an E3 ubiquitin ligase that promotes the ubiquitination of caspases and thereby prevents caspase activation. For this study, we developed a fluorescent probe to monitor DIAP1 turnover in the external sensory organ precursor (SOP) lineage of living Drosophila. The SOP divides asymmetrically to make the shaft, socket, and sheath cells, and the neuron that comprise each sensory organ. We found that the quantity of DIAP1 changed dramatically depending on the cell type and maturity, and that the temporal regulation of DIAP1 turnover determines whether caspases function nonapoptotically in cellular morphogenesis or cause cell death.
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Affiliation(s)
- Akiko Koto
- Department of Genetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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37
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The developmentally active and stress-inducible noncoding hsromega gene is a novel regulator of apoptosis in Drosophila. Genetics 2009; 183:831-52. [PMID: 19737742 DOI: 10.1534/genetics.109.108571] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The large nucleus limited noncoding hsromega-n RNA of Drosophila melanogaster is known to associate with a variety of heterogeneous nuclear RNA-binding proteins (hnRNPs) and certain other RNA-binding proteins to assemble the nucleoplasmic omega speckles. In this article, we show that RNAi-mediated depletion of this noncoding RNA dominantly suppresses apoptosis, in eye and other imaginal discs, triggered by induced expression of Rpr, Grim, or caspases (initiator as well as effector), all of which are key regulators/effectors of the canonical caspase-mediated cell death pathway. We also show, for the first time, a genetic interaction between the noncoding hsromega transcripts and the c-Jun N-terminal kinase (JNK) signaling pathway since downregulation of hsromega transcripts suppressed JNK activation. In addition, hsromega-RNAi also augmented the levels of Drosophila Inhibitor of Apoptosis Protein 1 (DIAP1) when apoptosis was activated. Suppression of induced cell death following depletion of hsromega transcripts was abrogated when the DIAP1-RNAi transgene was coexpressed. Our results suggest that the hsromega transcripts regulate cellular levels of DIAP1 via the hnRNP Hrb57A, which physically interacts with DIAP1, and any alteration in levels of the hsromega transcripts in eye disc cells enhances association between these two proteins. Our studies thus reveal a novel regulatory role of the hsromega noncoding RNA on the apoptotic cell death cascade through multiple paths. These observations add to the diversity of regulatory functions that the large noncoding RNAs carry out in the cells' life.
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38
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Caenorhabditis elegans caspase homolog CSP-2 inhibits CED-3 autoactivation and apoptosis in germ cells. Cell Death Differ 2009; 16:1385-94. [PMID: 19575016 PMCID: PMC2743765 DOI: 10.1038/cdd.2009.88] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In Caenorhabditis elegans, apoptosis in germ cells is mediated by the same core apoptotic machinery that controls apoptosis in somatic cells. These include the CED-3 caspase, the CED-3 activator CED-4, and the cell death inhibitor CED-9. However, germline apoptosis also differs from somatic apoptosis in its regulation. We found that CSP-3, a caspase homolog that blocks CED-3 autoactivation and apoptosis in somatic cells, does not affect apoptosis in germ cells. Interestingly, the second C. elegans caspase homolog, CSP-2, shares sequence similarity to both catalytic subunits of the CED-3 caspase, and surprisingly, contains a stretch of sequence that is almost identical to that of CSP-3. Unlike CSP-3 that acts specifically in somatic cells, loss of CSP-2 causes increased apoptosis only in germ cells, suggesting that CSP-2 is a germ cell-specific apoptosis inhibitor. Moreover, like CSP-3, CSP-2 associates with the CED-3 zymogen and inhibits its autoactivation, but does not inhibit CED-4-induced CED-3 activation or the activity of the activated CED-3 protease. Thus, two different C. elegans caspase homologs use the same mechanism to prevent caspase autoactivation and apoptosis in different tissues, suggesting that this could be a generally applicable strategy for regulating caspase activation and apoptosis.
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Orme M, Meier P. Inhibitor of apoptosis proteins in Drosophila: gatekeepers of death. Apoptosis 2009; 14:950-60. [PMID: 19495985 DOI: 10.1007/s10495-009-0358-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 05/01/2009] [Indexed: 01/25/2023]
Abstract
Regulation of apoptosis is crucial to ensure cellular viability, and failure to do so is linked to several human pathologies. The apoptotic cell death programme culminates in the activation of caspases, a family of highly specific cysteine proteases essential for the destruction of the cell. Although best known for their role in executing apoptosis, caspases also play important signalling roles in non-apoptotic processes, such as regulation of actin dynamics, innate immunity, cell proliferation, differentiation and survival. Under such conditions, caspases are activated without killing the cell. Caspase activation and activity is subject to complex regulation, and various cellular and viral inhibitors have been identified that control the activity of caspases in their apoptotic and non-apoptotic roles. Members of the Inhibitor of APoptosis (IAP) protein family ensure cell viability in Drosophila by directly binding to caspases and regulating their activities in a ubiquitin-dependent manner. The observation that IAPs are essential for cell survival in Drosophila, and are frequently deregulated in human cancer, contributing to tumourigenesis, chemoresistance, disease progression and poor patient survival, highlights the importance of this family of caspase regulators in health and disease. Here we summarise recent advances from Drosophila that start to elucidate how the cellular response to caspase activation is modulated by IAPs and their regulators.
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Affiliation(s)
- Mariam Orme
- The Breakthrough Toby Robins Breast Cancer Research Centre, Chester Beatty Laboratories, Institute of Cancer Research, London SW3 6JB, UK.
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40
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Apoptosis is triggered when prosurvival Bcl-2 proteins cannot restrain Bax. Proc Natl Acad Sci U S A 2008; 105:18081-7. [PMID: 18981409 DOI: 10.1073/pnas.0808691105] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A central issue in the control of apoptosis is whether its essential mediators Bax and Bak must be restrained by Bcl-2-like prosurvival relatives to prevent their damaging mitochondria and unleashing apoptosis. The issue is particularly vexed for Bax, which is largely a cytosolic monomer in unstressed cells. To determine whether Bax regulation requires its binding by prosurvival relatives, we replaced a conserved aspartate in its BH3 interaction domain with arginine. Bax D68R functioned and behaved like wild-type Bax in localization and activation but had greatly impaired binding to the prosurvival family members. Nevertheless, Bcl-x(L) remained able to block apoptosis induced by Bax D68R. Whereas cells with sufficient Bcl-x(L) tolerated expression of Bax D68R, it provoked apoptosis when Bcl-x(L) was absent, downregulated, or inactivated. Moreover, Bax D68R rendered membrane bound by a C-terminal anchor mutation overwhelmed endogenous Bcl-x(L) and killed cells. These unexpected results suggest that engagement of Bax by its prosurvival relatives is a major barrier to its full activation. We propose that the Bcl-2-like proteins must capture the small proportion of Bax molecules with an exposed BH3 domain, probably on the mitochondrial membrane, to prevent Bax-imposed cell death, but that Bcl-x(L) also controls Bax by other mechanisms.
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41
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Geng X, Shi Y, Nakagawa A, Yoshina S, Mitani S, Shi Y, Xue D. Inhibition of CED-3 zymogen activation and apoptosis in Caenorhabditis elegans by caspase homolog CSP-3. Nat Struct Mol Biol 2008; 15:1094-101. [PMID: 18776901 PMCID: PMC2574878 DOI: 10.1038/nsmb.1488] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 08/05/2008] [Indexed: 11/24/2022]
Abstract
Inhibitor of apoptosis (IAP) proteins have a crucial role in apoptosis, through negative regulation of caspases in species from fruitflies to mammals. In Caenorhabditis elegans, however, no IAP homolog or caspase inhibitor has been identified, calling into question how the cell-killing caspase CED-3 can be negatively regulated. Here we show that inactivation of the C. elegans csp-3 gene, which encodes a protein similar to the small subunit of the CED-3 caspase, causes cells that normally live to undergo apoptosis in a CED-3–dependent manner. Biochemical analysis reveals that CSP-3 associates with the large subunit of the CED-3 zymogen and inhibits zymogen autoactivation. However, CSP-3 does not block CED-3 activation induced by CED-4, nor does it inhibit the activity of the activated CED-3 protease. Therefore CSP-3 uses a previously unreported mechanism to protect cells from apoptosis.
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Affiliation(s)
- Xin Geng
- Department of Molecular, Cellular, and Developmental Biology, Campus Box 347, University of Colorado, Boulder, Colorado 80309, USA
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42
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Chowdhury I, Tharakan B, Bhat GK. Caspases - an update. Comp Biochem Physiol B Biochem Mol Biol 2008; 151:10-27. [PMID: 18602321 DOI: 10.1016/j.cbpb.2008.05.010] [Citation(s) in RCA: 259] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 05/23/2008] [Accepted: 05/23/2008] [Indexed: 02/07/2023]
Abstract
Caspases belong to a family of highly conserved aspartate-specific cysteine proteases and are members of the interleukin-1beta-converting enzyme family, present in multicellular organisms. The caspase gene family consists of 15 mammalian members that are grouped into two major sub-families, namely inflammatory caspases and apoptotic caspases. The apoptotic caspases are further subdivided into two sub-groups, initiator caspases and executioner caspases. The caspases form a caspase-cascade system that plays the central role in the induction, transduction and amplification of intracellular apoptotic signals for cell fate determination, regulation of immunity, and cellular proliferation and differentiation. The substrates of apoptotic caspases have been associated with cellular dismantling, while inflammatory caspases mediate the proteolytic activation of inflammatory cytokines. The activation of this delicate caspase-cascade system and its functions are regulated by a variety of regulatory molecules, such as the inhibitor of apoptosis protein (IAP), FLICE, calpain, and Ca(2+). Based on the available literature we have reviewed and discussed the members of the caspase family, caspase-cascade system, caspase-regulating molecules and their apoptotic and non-apoptotic functions in cellular life and death. Also recent progress in the molecular structure and physiological role of non-mammalian caspases such as paracaspases, metacaspases and caspase-like-protease family members are included in relation to that of mammalian species.
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Affiliation(s)
- Indrajit Chowdhury
- Department of Obstetrics and Gynecology, Morehouse School of Medicine, 720 Westview Drive, SW., Atlanta, GA 30310, USA
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Sellamuthu S, Shin BH, Lee ES, Rho SH, Hwang W, Lee YJ, Han HE, Kim JI, Park WJ. Engineering of protease variants exhibiting altered substrate specificity. Biochem Biophys Res Commun 2008; 371:122-6. [PMID: 18413229 DOI: 10.1016/j.bbrc.2008.04.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 04/03/2008] [Indexed: 10/22/2022]
Abstract
By using an improved genetic screening system, variants of the HAV 3CP protease which exhibit altered P2 specificity were obtained. We randomly mutated the His145, Lys146, Lys147, and Leu155 residues that constitute the S2 pocket of 3CP and then isolated variants that preferred substrates with Gln over the original Thr at the P2 position using a yeast-based screening method. One of the isolated variants cleaved the Gln-containing peptide substrate more efficiently in vitro, proving the efficiency of our method in isolating engineered proteases with desired substrate selectivity.
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Affiliation(s)
- Saravanan Sellamuthu
- Department of Life Science, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea
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Dewson G, Kratina T, Sim HW, Puthalakath H, Adams JM, Colman PM, Kluck RM. To trigger apoptosis, Bak exposes its BH3 domain and homodimerizes via BH3:groove interactions. Mol Cell 2008; 30:369-80. [PMID: 18471982 DOI: 10.1016/j.molcel.2008.04.005] [Citation(s) in RCA: 257] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 02/24/2008] [Accepted: 04/11/2008] [Indexed: 10/22/2022]
Abstract
The Bcl-2 relative Bak is thought to drive apoptosis by forming homo-oligomers that permeabilize mitochondria, but how it is activated and oligomerizes is unclear. To clarify these pivotal steps toward apoptosis, we have characterized multiple random loss-of-function Bak mutants and explored the mechanism of Bak conformation change during apoptosis. Single missense mutations located to the alpha helix 2-5 region of Bak, with most altering the BH3 domain or hydrophobic groove (BH1 domain). Loss of function invariably corresponded to impaired ability to oligomerize. An essential early step in Bak activation was shown to be exposure of the BH3 domain, which became reburied in dimers. We demonstrate that oligomerization involves insertion of the BH3 domain of one Bak molecule into the groove of another and may produce symmetric Bak dimers. We conclude that this BH3:groove interaction is essential to nucleate Bak oligomerization, which in turn is required for its proapoptotic function.
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Affiliation(s)
- Grant Dewson
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, Victoria 3050, Australia
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45
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Sir2 mediates apoptosis through JNK-dependent pathways in Drosophila. Proc Natl Acad Sci U S A 2008; 105:8673-8. [PMID: 18562277 DOI: 10.1073/pnas.0803837105] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Increased expression of the histone deacetylase sir2 has been reported to extend the life span of diverse organisms including yeast, Caenorhabditis elegans, and Drosophila melanogaster. A small molecule activator of Sir2, resveratrol, has also been suggested to extend the fitness and survival of these simple model organisms as well as mice fed high calorie diets. However, other studies in yeast have shown that Sir2 itself may prevent life extension, and high expression levels of Sir2 can be toxic to yeast and mouse cells. This conflicting evidence highlights the importance of understanding the mechanisms by which Sir2 expression or activation affects survival of organisms. To investigate the downstream signaling pathways affected by Sir2 in Drosophila, we generated transgenic flies expressing sir2. Here, we show that overexpression of sir2 in Drosophila promotes caspase-dependent but p53-independent apoptosis that is mediated by the JNK and FOXO signaling pathways. Furthermore, we find that a loss-of-function sir2 mutant partially prevents apoptosis induced by UV irradiation in the eye. Together, these results suggest that Sir2 normally participates in the regulation of cell survival and death in Drosophila.
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Xu L, Zhu J, Hu X, Zhu H, Kim HT, LaBaer J, Goldberg A, Yuan J. c-IAP1 cooperates with Myc by acting as a ubiquitin ligase for Mad1. Mol Cell 2008; 28:914-22. [PMID: 18082613 DOI: 10.1016/j.molcel.2007.10.027] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 09/10/2007] [Accepted: 10/30/2007] [Indexed: 11/30/2022]
Abstract
c-IAP1, a member of the inhibitor of apoptosis protein (IAP) family and a RING finger ubiquitin ligase (E3), has been proposed to be an important oncogene. In many types of cancers, the levels of c-IAP1 are upregulated, which contributes positively to tumorigenesis. However, the mechanism by which c-IAP1 promotes tumorigenesis has proven elusive. Although proteins in the IAP family may function as caspase inhibitors, c-IAP1 was shown to be a poor inhibitor of caspases. Here we show that c-IAP1 catalyzes ubiquitination of Max-dimerization protein-1 (Mad1), a cellular antagonist of Myc. Ubiquitination of Mad1 by c-IAP1 accelerates its degradation by the 26S proteasome pathway, and this reduction of the Mad1 levels cooperates with Myc to promote cell proliferation. Our results demonstrate that c-IAP1 exerts its oncogenic functions by promoting the degradation of an important negative regulator in the Myc pathway.
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Affiliation(s)
- Lei Xu
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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Westein SJ, Scott FL, Hawkins CJ. Analysis of the minimal specificity of CED-3 using a yeast transcriptional reporter system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1783:448-54. [PMID: 17996738 DOI: 10.1016/j.bbamcr.2007.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/28/2007] [Accepted: 10/04/2007] [Indexed: 10/22/2022]
Abstract
Determination of the substrate specificity of site-specific proteases helps define their physiological roles. We developed a yeast-based system for defining the minimal substrate specificity of site-specific proteases, within the context of a protein. Using this system, we characterized the P4-P1 substrate specificity of the nematode apoptotic caspase CED-3. Apart from an absolute requirement for aspartate at the P1 position, CED-3 is a relatively promiscuous caspase capable of cleaving substrates bearing many amino acids at P4-P2 sites.
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Affiliation(s)
- Sarah J Westein
- Department of Biochemistry, La Trobe University, Bundoora, Victoria, Australia
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Chandraratna D, Lawrence N, Welchman DP, Sanson B. An in vivo model of apoptosis: linking cell behaviours and caspase substrates in embryos lacking DIAP1. J Cell Sci 2007; 120:2594-608. [PMID: 17636001 DOI: 10.1242/jcs.03472] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The apoptotic phenotype is characterised by dynamic changes in cell behaviours such as cell rounding and blebbing, followed by chromatin condensation and cell fragmentation. Whereas the biochemical pathways leading to caspase activation have been actively studied, much less is known about how caspase activity changes cell behaviours during apoptosis. Here, we address this question using early Drosophila melanogaster embryos lacking DIAP1. Reflecting its central role in the inhibition of apoptosis, loss of DIAP1 causes massive caspase activation. We generated DIAP1-depleted embryos by either using homozygous null mutants for thread, the gene coding DIAP1, or by ectopically expressing in early embryos the RGH protein Reaper, which inhibits DIAP1. We show that (1) all cells in embryos lacking DIAP1 follow synchronously the stereotypic temporal sequence of behaviours described for apoptotic mammalian cells and (2) these cell behaviours specifically require caspase activity and are not merely a consequence of cellular stress. Next, we analyse the dynamic changes in the localisation of actomyosin, Discs large, Bazooka and DE-cadherin in the course of apoptosis. We show that early changes in Bazooka and Discs large correlate with early processing of these proteins by caspases. DE-cadherin and Myosin light chain do not appear to be cleaved, but their altered localisation can be explained by cleavage of known regulators. This illustrates how embryos lacking DIAP1 can be used to characterise apoptotic changes in the context of an embryo, thus providing an unprecedented in vivo model in which thousands of cells initiate apoptosis simultaneously.
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echinus, required for interommatidial cell sorting and cell death in the Drosophila pupal retina, encodes a protein with homology to ubiquitin-specific proteases. BMC DEVELOPMENTAL BIOLOGY 2007; 7:82. [PMID: 17612403 PMCID: PMC1950886 DOI: 10.1186/1471-213x-7-82] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 07/05/2007] [Indexed: 01/03/2023]
Abstract
BACKGROUND Programmed cell death is used to remove excess cells between ommatidia in the Drosophila pupal retina. This death is required to establish the crystalline, hexagonal packing of ommatidia that characterizes the adult fly eye. In previously described echinus mutants, interommatidial cell sorting, which precedes cell death, occurred relatively normally. Interommatidial cell death was partially suppressed, resulting in adult eyes that contained excess pigment cells, and in which ommatidia were mildly disordered. These results have suggested that echinus functions in the pupal retina primarily to promote interommatidial cell death. RESULTS We generated a number of new echinus alleles, some likely null mutants. Analysis of these alleles provides evidence that echinus has roles in cell sorting as well as cell death. echinus encodes a protein with homology to ubiquitin-specific proteases. These proteins cleave ubiquitin-conjugated proteins at the ubiquitin C-terminus. The echinus locus encodes multiple splice forms, including two proteins that lack residues thought to be critical for deubiquitination activity. Surprisingly, ubiquitous expression in the eye of versions of Echinus that lack residues critical for ubiquitin specific protease activity, as well as a version predicted to be functional, rescue the echinus loss-of-function phenotype. Finally, genetic interactions were not detected between echinus loss and gain-of-function and a number of known apoptotic regulators. These include Notch, EGFR, the caspases Dronc, Drice, Dcp-1, Dream, the caspase activators, Rpr, Hid, and Grim, the caspase inhibitor DIAP1, and Lozenge or Klumpfuss. CONCLUSION The echinus locus encodes multiple splice forms of a protein with homology to ubiquitin-specific proteases, but protease activity is unlikely to be required for echinus function, at least when echinus is overexpressed. Characterization of likely echinus null alleles and genetic interactions suggests that echinus acts at a novel point(s) to regulate interommatidial cell sorting and/or cell death in the fly eye.
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Köhler F. A co-localization assay for the analysis of protein-protein interactions. Gene 2007; 388:14-8. [PMID: 17157449 DOI: 10.1016/j.gene.2006.07.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 07/19/2006] [Accepted: 07/25/2006] [Indexed: 11/21/2022]
Abstract
The understanding and analysis of protein associations in living cells is a major goal of molecular biology. Here, we describe an assay for the analysis of protein-protein interactions based on the co-localization of a fused site-specific protease with a cleavable reporter in close proximity to the interaction partner under examination. We exemplified this scheme in the temperature-sensitive Saccharomyces cerevisiae cdc25-2 mutant strain using the nuclear inclusion protease of tobacco etch virus fused to the adaptor protein growth factor receptor binding protein 2 (Grb2). The growth-defective phenotype of cdc25-2 was complemented by expression of a membrane-targeted constitutively active Ras protein, which contained a TEV protease substrate sequence allowing for release from the membrane upon proteolysis. Interaction of Grb2 with the membrane-targeted intracellular domain of the oncogene vErbB resulted in co-localization of the TEV protease with its substrate, release of Ras from the membrane and restoration of the temperature-sensitive phenotype of cdc25-2. The flexibility of the general scheme of this approach may allow for its application in many different assay scenarios and may represent a suitable alternative in cases where other approaches fail.
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Affiliation(s)
- Fabian Köhler
- Institute for Biology III, Albert-Ludwigs-University of Freiburg and Max-Planck-Institute for Immunobiology, Stuebeweg 51, 79108 Freiburg, Germany.
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