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Sahoo G, Samal D, Khandayataray P, Murthy MK. A Review on Caspases: Key Regulators of Biological Activities and Apoptosis. Mol Neurobiol 2023; 60:5805-5837. [PMID: 37349620 DOI: 10.1007/s12035-023-03433-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 06/06/2023] [Indexed: 06/24/2023]
Abstract
Caspases are proteolytic enzymes that belong to the cysteine protease family and play a crucial role in homeostasis and programmed cell death. Caspases have been broadly classified by their known roles in apoptosis (caspase-3, caspase-6, caspase-7, caspase-8, and caspase-9 in mammals) and in inflammation (caspase-1, caspase-4, caspase-5, and caspase-12 in humans, and caspase-1, caspase-11, and caspase-12 in mice). Caspases involved in apoptosis have been subclassified by their mechanism of action as either initiator caspases (caspase-8 and caspase-9) or executioner caspases (caspase-3, caspase-6, and caspase-7). Caspases that participate in apoptosis are inhibited by proteins known as inhibitors of apoptosis (IAPs). In addition to apoptosis, caspases play a role in necroptosis, pyroptosis, and autophagy, which are non-apoptotic cell death processes. Dysregulation of caspases features prominently in many human diseases, including cancer, autoimmunity, and neurodegenerative disorders, and increasing evidence shows that altering caspase activity can confer therapeutic benefits. This review covers the different types of caspases, their functions, and their physiological and biological activities and roles in different organisms.
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Affiliation(s)
- Gayatri Sahoo
- Department of Zoology, PSSJ College, Banarpal, 759128, Odisha, India
| | - Dibyaranjan Samal
- Department of Biotechnology, Academy of Management and Information Technology (AMIT, affiliated to Utkal University), Khurda, 752057, Odisha, India
| | | | - Meesala Krishna Murthy
- Department of Allied Health Sciences, Chitkara School of Health Sciences, Chitkara University, Rajpura, Punjab, 140401, India.
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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
,
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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Deep Conservation of Hid-Like RHG Gene Family Homologs in Winged Insects Revealed by "Taxon Hopping" BLAST. INSECTS 2021; 12:insects12110957. [PMID: 34821758 PMCID: PMC8620624 DOI: 10.3390/insects12110957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/16/2022]
Abstract
Together with sickle (skl), the Drosophila paralogs reaper (rpr), head involution defective (hid), and grim (RHG) control a critical switch in the induction of programmed cell death. RHG homologs have been identified in other dipteran and lepidopteran species but not beyond. Revisiting this issue with a "taxon hopping" BLAST search strategy in current genome and transcriptome resources, I detected high confidence RHG homologs in Coleoptera, Hymenoptera, Hemiptera, and Dictyoptera. Analyses of gene structure and protein sequence conservation revealed aconserved splicing pattern and highly conserved amino acid residues at both the N- and C-terminal ends that identify hid as the most ancestrally organized RHG gene family member in Drosophila. hid-like RHG homologs were also detected in mosquitoes, redefining their michelob_x (mx) genes as an expansion of derived RHG homologs. Only singleton homologs were detected in the large majority of other insect clades. Lepidopteran RHG homologs, however, stand out by producing an evolutionarily-derived splice isoform, identified in previous work, in addition to the newly detected hid-like isoform. Exceptional sequence diversification of select RHG homologs at the family- and genus-level explain their previous elusiveness in important insect genome model species like the red flour beetle Tribolium castaneum and the pea aphid Acyrthosiphon pisum. Combined, these findings expand the minimal age of the RHG gene family by about 100 million years and open new avenues for molecular cell death studies in insects.
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Arthurton L, Nahotko DA, Alonso J, Wendler F, Baena‐Lopez LA. Non-apoptotic caspase activation preserves Drosophila intestinal progenitor cells in quiescence. EMBO Rep 2020; 21:e48892. [PMID: 33135280 PMCID: PMC7726796 DOI: 10.15252/embr.201948892] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/21/2020] [Accepted: 10/01/2020] [Indexed: 12/11/2022] Open
Abstract
Caspase malfunction in stem cells often precedes the appearance and progression of multiple types of cancer, including human colorectal cancer. However, the caspase-dependent regulation of intestinal stem cell properties remains poorly understood. Here, we demonstrate that Dronc, the Drosophila ortholog of caspase-9/2 in mammals, limits the number of intestinal progenitor cells and their entry into the enterocyte differentiation programme. Strikingly, these unexpected roles for Dronc are non-apoptotic and have been uncovered under experimental conditions without epithelial replenishment. Supporting the non-apoptotic nature of these functions, we show that they require the enzymatic activity of Dronc, but are largely independent of the apoptotic pathway. Alternatively, our genetic and functional data suggest that they are linked to the caspase-mediated regulation of Notch signalling. Our findings provide novel insights into the non-apoptotic, caspase-dependent modulation of stem cell properties that could improve our understanding of the origin of intestinal malignancies.
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Affiliation(s)
- Lewis Arthurton
- Sir William Dunn School of PathologyUniversity of OxfordOxfordshireUK
| | | | - Jana Alonso
- Laboratorio de Agrobiología Juan José Bravo Rodríguez (Cabildo Insular de La Palma)Unidad Técnica del IPNA‐CSICSanta Cruz de La PalmaSpain
| | - Franz Wendler
- Sir William Dunn School of PathologyUniversity of OxfordOxfordshireUK
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5
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Functional characterization of the Drosophila suzukii pro-apoptotic genes reaper, head involution defective and grim. Apoptosis 2020; 25:864-874. [PMID: 33113043 DOI: 10.1007/s10495-020-01640-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2020] [Indexed: 12/18/2022]
Abstract
Apoptosis is a fundamental process for the elimination of damaged or unwanted cells, and is a key aspect of development. It is triggered by pro-apoptotic genes responding to the intrinsic pathway that senses cell stress or the extrinsic pathway that responds to signals from other cells. The disruption of these genes can therefore lead to developmental defects and disease. Pro-apoptotic genes have been studied in detail in the fruit fly Drosophila melanogaster, a widely-used developmental model. However, little is known about the corresponding genes in its relative D. suzukii, a pest of soft fruit crops that originates from Asia but is now an invasive species in many other regions. The characterization of D. suzukii pro-apoptotic genes could lead to the development of transgenic sexing strains for pest management. Here, we describe the isolation and characterization of the pro-apoptotic genes reaper (Dsrpr), head involution defective (Dshid) and grim (Dsgrim) from a laboratory strain of D. suzukii. We determined their expression profiles during development, revealing that all three genes are expressed throughout development but Dsrpr is expressed most strongly, especially at the pupal stage. Functional analysis was carried out by expressing single genes or pairs (linked by a 2A peptide) in S2 cell death assays, indicating that Dsgrim and Dshid are more potent pro-apoptotic genes than Dsrpr, and the lethality can be significantly enhanced by co-expression of two genes. Therefore, the binary or multiple expression of different pro-apoptotic genes can be considered to build an efficient transgenic sexing system in D. suzukii.
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Millet-Boureima C, Chingle R, Lubell WD, Gamberi C. Cyst Reduction in a Polycystic Kidney Disease Drosophila Model Using Smac Mimics. Biomedicines 2019; 7:biomedicines7040082. [PMID: 31635379 PMCID: PMC6966561 DOI: 10.3390/biomedicines7040082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 10/11/2019] [Accepted: 10/15/2019] [Indexed: 12/13/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is an inherited malady affecting 12.5 million people worldwide. Therapeutic options to treat PKD are limited, due in part to lack of precise knowledge of underlying pathological mechanisms. Mimics of the second mitochondria-derived activator of caspases (Smac) have exhibited activity as antineoplastic agents and reported recently to ameliorate cysts in a murine ADPKD model, possibly by differentially targeting cystic cells and sparing the surrounding tissue. A first-in-kind Drosophila PKD model has now been employed to probe further the activity of novel Smac mimics. Substantial reduction of cystic defects was observed in the Malpighian (renal) tubules of treated flies, underscoring mechanistic conservation of the cystic pathways and potential for efficient testing of drug prototypes in this PKD model. Moreover, the observed differential rescue of the anterior and posterior tubules overall, and within their physiologically diverse intermediate and terminal regions implied a nuanced response in distinct tubular regions contingent upon the structure of the Smac mimic. Knowledge gained from studying Smac mimics reveals the capacity for the Drosophila model to precisely probe PKD pharmacology highlighting the value for such critical evaluation of factors implicated in renal function and pathology.
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Affiliation(s)
| | - Ramesh Chingle
- Département de Chimie, Université de Montréal, Montreal, QC H3T 1J4, Canada.
| | - William D Lubell
- Département de Chimie, Université de Montréal, Montreal, QC H3T 1J4, Canada.
| | - Chiara Gamberi
- Biology Department, Concordia University, Montreal, QC H4B 1R6, Canada.
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Singh A, Permar V, Jain RK, Goswami S, Kumar RR, Canto T, Palukaitis P, Praveen S. Induction of cell death by tospoviral protein NSs and the motif critical for cell death does not control RNA silencing suppression activity. Virology 2017; 508:108-117. [PMID: 28527340 DOI: 10.1016/j.virol.2017.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 10/19/2022]
Abstract
Groundnut bud necrosis virus induces necrotic symptoms in different hosts. Previous studies showed reactive oxygen species-mediated programmed cell death (PCD) resulted in necrotic symptoms. Transgenic expression of viral protein NSs mimics viral symptoms. Here, we showed a role for NSs in influencing oxidative burst in the cell, by analyzing H2O2 accumulation, activities of antioxidant enzymes and expression levels of vacuolar processing enzymes, H2O2-responsive microRNA 319a.2 plus its possible target metacaspase-8. The role of NSs in PCD, was shown using two NSs mutants: one in the Trp/GH3 motif (a homologue of pro-apototic domain) (NSsS189R) and the other in a non-Trp/GH3 motif (NSsL172R). Tobacco rattle virus (TRV) expressing NSsS189R enhanced the PCD response, but not TRV-NSsL172R, while RNA silencing suppression activity was lost in TRV-NSsL172R, but not in TRV-NSsS189R. Therefore, we propose dual roles of NSs in RNA silencing suppression and induction of cell death, controlled by different motifs.
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Affiliation(s)
- Ajeet Singh
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India
| | - Vipin Permar
- Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi 110012, India
| | - R K Jain
- Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi 110012, India
| | - Suneha Goswami
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India
| | - Ranjeet Ranjan Kumar
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India
| | - Tomas Canto
- Centro de Investigaciones Biológicas, CIB, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Peter Palukaitis
- Department of Horticultural Science, Seoul Women's University, Seoul 01797, South Korea
| | - Shelly Praveen
- Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India.
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8
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Birkinshaw RW, Czabotar PE. The BCL-2 family of proteins and mitochondrial outer membrane permeabilisation. Semin Cell Dev Biol 2017; 72:152-162. [PMID: 28396106 DOI: 10.1016/j.semcdb.2017.04.001] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 03/03/2017] [Accepted: 04/06/2017] [Indexed: 01/24/2023]
Abstract
Apoptosis is a form of programmed cell death critical for the development and homeostasis of multicellular organisms. A key event within the mitochondrial pathway to apoptosis is the permeabilisation of the mitochondrial outer membrane (MOM), a point of no return in apoptotic progression. This event is governed by a complex interplay of interactions between BCL-2 family members. Here we discuss the roles of opposing factions within the family. We focus on the structural details of these interactions, how they promote or prevent apoptosis and recent developments towards understanding the conformational changes of BAK and BAX that lead to MOM permeabilisation. These interactions and structural insights are of particular interest for drug discovery, as highlighted by the development of therapeutics that target pro-survival family members and restore apoptosis in cancer cells.
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Affiliation(s)
- Richard W Birkinshaw
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Peter E Czabotar
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia.
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9
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Pinto-Teixeira F, Konstantinides N, Desplan C. Programmed cell death acts at different stages of Drosophila neurodevelopment to shape the central nervous system. FEBS Lett 2016; 590:2435-2453. [PMID: 27404003 DOI: 10.1002/1873-3468.12298] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 07/08/2016] [Accepted: 07/11/2016] [Indexed: 12/19/2022]
Abstract
Nervous system development is a process that integrates cell proliferation, differentiation, and programmed cell death (PCD). PCD is an evolutionary conserved mechanism and a fundamental developmental process by which the final cell number in a nervous system is established. In vertebrates and invertebrates, PCD can be determined intrinsically by cell lineage and age, as well as extrinsically by nutritional, metabolic, and hormonal states. Drosophila has been an instrumental model for understanding how this mechanism is regulated. We review the role of PCD in Drosophila central nervous system development from neural progenitors to neurons, its molecular mechanism and function, how it is regulated and implemented, and how it ultimately shapes the fly central nervous system from the embryo to the adult. Finally, we discuss ideas that emerged while integrating this information.
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Affiliation(s)
- Filipe Pinto-Teixeira
- Department of Biology, New York University 1009 Silver Center 100 Washington Square East, New York, NY 10003, USA.,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi 129188, UAE
| | - Nikolaos Konstantinides
- Department of Biology, New York University 1009 Silver Center 100 Washington Square East, New York, NY 10003, USA
| | - Claude Desplan
- Department of Biology, New York University 1009 Silver Center 100 Washington Square East, New York, NY 10003, USA.,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi 129188, UAE
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Abstract
Drosophila has served as a particularly attractive model to study cell death due to the vast array of tools for genetic manipulation under defined spatial and temporal conditions in vivo as well as in cultured cells. These genetic methods have been well supplemented by enzymatic assays and a panel of antibodies recognizing cell death markers. This chapter discusses reporters, mutants, and assays used by various laboratories to study cell death in the context of development and in response to external insults.
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Affiliation(s)
- Deepika Vasudevan
- Department of Cell Biology, New York University School of Medicine, 550 First Ave., New York, NY, 10016, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, 550 First Ave., New York, NY, 10016, USA.
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Clavier A, Rincheval-Arnold A, Colin J, Mignotte B, Guénal I. Apoptosis in Drosophila: which role for mitochondria? Apoptosis 2015; 21:239-51. [DOI: 10.1007/s10495-015-1209-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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12
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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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Abstract
The apoptotic machinery is highly conserved throughout evolution, and central to the regulation of apoptosis is the caspase family of cysteine proteases. Insights into the regulation and function of apoptosis in mammals have come from studies using model organisms. Drosophila provides an exceptional model system for identifying the function of conserved mechanisms regulating apoptosis, especially during development. The characteristic patterns of apoptosis during Drosophila development have been well described, as has the apoptotic response following DNA damage. The focus of this discussion is to introduce methodologies for monitoring apoptosis during Drosophila development and also in Drosophila cell lines.
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Affiliation(s)
- Donna Denton
- Centre for Cancer Biology, University of South Australia, Adelaide, South Australia 5001, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia, Adelaide, South Australia 5001, Australia
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Cell death in development: Signaling pathways and core mechanisms. Semin Cell Dev Biol 2015; 39:12-9. [PMID: 25668151 DOI: 10.1016/j.semcdb.2015.02.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/22/2015] [Accepted: 02/02/2015] [Indexed: 11/20/2022]
Abstract
Programmed cell death eliminates unneeded and dangerous cells in a timely and effective manner during development. In this review, we examine the role cell death plays during development in worms, flies and mammals. We discuss signaling pathways that regulate developmental cell death, and describe how they communicate with the core cell death pathways. In most organisms, the majority of developmental cell death is seen in the nervous system. Therefore we focus on what is known about the regulation of developmental cell death in this tissue. Understanding how the cell death is regulated during development may provide insight into how this process can be manipulated in the treatment of disease.
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Creagh EM. Caspase crosstalk: integration of apoptotic and innate immune signalling pathways. Trends Immunol 2014; 35:631-640. [PMID: 25457353 DOI: 10.1016/j.it.2014.10.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 01/30/2023]
Abstract
The caspase family of cysteine proteases has been functionally divided into two groups: those involved in apoptosis and those involved in innate immune signalling. Recent findings have identified 'apoptotic' caspases within inflammasome complexes and revealed that 'inflammatory' caspases are capable of inducing cell death, suggesting that the earlier view of caspase function may have been overly simplistic. Here, I review evidence attributing nonclassical functions to many caspases and propose that caspases serve as critical mediators in the integration of apoptotic and inflammatory pathways, thereby forming an integrated signalling system that regulates cell death and innate immune responses during development, infection, and homeostasis.
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Affiliation(s)
- Emma M Creagh
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland.
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Zhang B, Mehrotra S, Ng WL, Calvi BR. Low levels of p53 protein and chromatin silencing of p53 target genes repress apoptosis in Drosophila endocycling cells. PLoS Genet 2014; 10:e1004581. [PMID: 25211335 PMCID: PMC4161308 DOI: 10.1371/journal.pgen.1004581] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 07/03/2014] [Indexed: 12/23/2022] Open
Abstract
Apoptotic cell death is an important response to genotoxic stress that prevents oncogenesis. It is known that tissues can differ in their apoptotic response, but molecular mechanisms are little understood. Here, we show that Drosophila polyploid endocycling cells (G/S cycle) repress the apoptotic response to DNA damage through at least two mechanisms. First, the expression of all the Drosophila p53 protein isoforms is strongly repressed at a post-transcriptional step. Second, p53-regulated pro-apoptotic genes are epigenetically silenced in endocycling cells, preventing activation of a paused RNA Pol II by p53-dependent or p53-independent pathways. Over-expression of the p53A isoform did not activate this paused RNA Pol II complex in endocycling cells, but over-expression of the p53B isoform with a longer transactivation domain did, suggesting that dampened p53B protein levels are crucial for apoptotic repression. We also find that the p53A protein isoform is ubiquitinated and degraded by the proteasome in endocycling cells. In mitotic cycling cells, p53A was the only isoform expressed to detectable levels, and its mRNA and protein levels increased after irradiation, but there was no evidence for an increase in protein stability. However, our data suggest that p53A protein stability is regulated in unirradiated cells, which likely ensures that apoptosis does not occur in the absence of stress. Without irradiation, both p53A protein and a paused RNA pol II were pre-bound to the promoters of pro-apoptotic genes, preparing mitotic cycling cells for a rapid apoptotic response to genotoxic stress. Together, our results define molecular mechanisms by which different cells in development modulate their apoptotic response, with broader significance for the survival of normal and cancer polyploid cells in mammals. In order to maintain genome integrity, eukaryotic cells have evolved multiple ways to respond to DNA damage stress. One of the major cellular responses is apoptosis, during which the cell undergoes programmed cell death in order to prevent the propagation of the damaged genome to daughter cells. Although clinical observations and other studies have shown that tissues can differ in their apoptotic response, the molecular mechanisms underlying these differences are largely unknown. We have shown in our model system, Drosophila, that endocycling cells do not initiate cell death in response to DNA damage. The endocycle is a cell cycle variation that is widely found in nature and conserved from plant to animals. During the endocycle, cells duplicate their genomic DNA but do not enter mitosis to segregate chromosomes, resulting in a polyploid genome content. In this study, we investigate how the apoptotic response to DNA damage is repressed in endocycling cells. We find that the Drosophila ortholog of the human p53 tumor suppressor protein is expressed at very low levels in endocycling cells. Moreover, the downstream pro-apoptotic genes that are regulated by p53 are epigenetically silenced in endocycling cells. Our results provide important insights into tissue-specific apoptotic responses in development, with possible broader impact on understanding radiation therapy response and cancer of different tissues.
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Affiliation(s)
- Bingqing Zhang
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Sonam Mehrotra
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Wei Lun Ng
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Brian R. Calvi
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
- * E-mail:
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Denton D, Aung-Htut MT, Kumar S. Developmentally programmed cell death in Drosophila. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3499-3506. [DOI: 10.1016/j.bbamcr.2013.06.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 06/16/2013] [Indexed: 12/24/2022]
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Abstract
Bunyaviruses are the largest known family of RNA viruses, infecting vertebrates, insects, and plants. Here we isolated three novel bunyaviruses from mosquitoes sampled in Côte d'Ivoire, Ghana, and Uganda. The viruses define a highly diversified monophyletic sister clade to all members of the genus Orthobunyavirus and are virtually equidistant to orthobunyaviruses and tospoviruses. Maximal amino acid identities between homologous putative proteins of the novel group and orthobunyaviruses ranged between 12 and 25%. The type isolates, tentatively named Herbert virus (HEBV), Taï virus (TAIV), and Kibale virus (KIBV), comprised genomes with L, M, and S segments of about 7.4 kb, 2.7 kb, and 1.1 kb, respectively. HEBV, TAIV, and KIBV encode the shortest bunyavirus M segments known and did not seem to encode NSs and NSm proteins but contained an elongated L segment with an ∼500-nucleotide (nt) insertion that shows no identity to other bunyaviruses. The viruses replicated to high titers in insect cells but did not replicate in vertebrate cells. The enveloped virions were 90 to 110 nm in diameter and budded at cellular membranes with morphological features typical of the Golgi complex. Viral RNA recovered from infected cells showed 5'-terminal nontemplated sequences of 9 to 22 nt, suggestive of cap snatching during mRNA synthesis, as described for other bunyaviruses. Northern blotting identified RNA species of full and reduced lengths, suggested upon analogy with other bunyaviruses to constitute antigenomic-sense cRNA and transcript mRNAs, respectively. Functional studies will be necessary to determine if this group of viruses constitutes a novel genus in the bunyavirus family.
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Berthelet J, Dubrez L. Regulation of Apoptosis by Inhibitors of Apoptosis (IAPs). Cells 2013; 2:163-87. [PMID: 24709650 PMCID: PMC3972657 DOI: 10.3390/cells2010163] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 01/05/2023] Open
Abstract
Abstract Inhibitors of Apoptosis (IAPs) are a family of proteins with various biological functions including regulation of innate immunity and inflammation, cell proliferation, cell migration and apoptosis. They are characterized by the presence of at least one N-terminal baculoviral IAP repeat (BIR) domain involved in protein-protein interaction. Most of them also contain a C-terminal RING domain conferring an E3-ubiquitin ligase activity. In drosophila, IAPs are essential to ensure cell survival, preventing the uncontrolled activation of the apoptotic protease caspases. In mammals, IAPs can also regulate apoptosis through controlling caspase activity and caspase-activating platform formation. Mammalian IAPs, mainly X-linked IAP (XIAP) and cellular IAPs (cIAPs) appeared to be important determinants of the response of cells to endogenous or exogenous cellular injuries, able to convert the survival signal into a cell death-inducing signal. This review highlights the role of IAP in regulating apoptosis in Drosophila and Mammals.
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Affiliation(s)
- Jean Berthelet
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
| | - Laurence Dubrez
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
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Lee G, Sehgal R, Wang Z, Nair S, Kikuno K, Chen CH, Hay B, Park JH. Essential role of grim-led programmed cell death for the establishment of corazonin-producing peptidergic nervous system during embryogenesis and metamorphosis in Drosophila melanogaster. Biol Open 2013; 2:283-94. [PMID: 23519152 PMCID: PMC3603410 DOI: 10.1242/bio.20133384] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/10/2012] [Indexed: 11/04/2022] Open
Abstract
In Drosophila melanogaster, combinatorial activities of four death genes, head involution defective (hid), reaper (rpr), grim, and sickle (skl), have been known to play crucial roles in the developmentally regulated programmed cell death (PCD) of various tissues. However, different expression patterns of the death genes also suggest distinct functions played by each. During early metamorphosis, a great number of larval neurons unfit for adult life style are removed by PCD. Among them are eight pairs of corazonin-expressing larval peptidergic neurons in the ventral nerve cord (vCrz). To reveal death genes responsible for the PCD of vCrz neurons, we examined extant and recently available mutations as well as RNA interference that disrupt functions of single or multiple death genes. We found grim as a chief proapoptotic gene and skl and rpr as minor ones. The function of grim is also required for PCD of the mitotic sibling cells of the vCrz neuronal precursors (EW3-sib) during embryonic neurogenesis. An intergenic region between grim and rpr, which, it has been suggested, may enhance expression of three death genes in embryonic neuroblasts, appears to play a role for the vCrz PCD, but not for the EW3-sib cell death. The death of vCrz neurons and EW3-sib is triggered by ecdysone and the Notch signaling pathway, respectively, suggesting distinct regulatory mechanisms of grim expression in a cell- and developmental stage-specific manner.
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Affiliation(s)
- Gyunghee Lee
- Neurogenetics Laboratory, Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, TN 37996 , USA
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Anhezini L, Saita AP, Costa MS, Ramos RGP, Simon CR. Fhosencodes aDrosophilaFormin-Like Protein participating in autophagic programmed cell death. Genesis 2012; 50:672-84. [DOI: 10.1002/dvg.22025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 03/01/2012] [Accepted: 03/05/2012] [Indexed: 01/12/2023]
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Abstract
Programmed cell death (PCD) plays a fundamental role in animal development and tissue homeostasis. Abnormal regulation of this process is associated with a wide variety of human diseases, including immunological and developmental disorders, neurodegeneration, and cancer. Here, we provide a brief historical overview of the field and reflect on the regulation, roles, and modes of PCD during animal development. We also discuss the function and regulation of apoptotic proteins, including caspases, the key executioners of apoptosis, and review the nonlethal functions of these proteins in diverse developmental processes, such as cell differentiation and tissue remodeling. Finally, we explore a growing body of work about the connections between apoptosis, stem cells, and cancer, focusing on how apoptotic cells release a variety of signals to communicate with their cellular environment, including factors that promote cell division, tissue regeneration, and wound healing.
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Shukla A, Tapadia MG. Differential localization and processing of apoptotic proteins in Malpighian tubules of Drosophila during metamorphosis. Eur J Cell Biol 2011; 90:72-80. [DOI: 10.1016/j.ejcb.2010.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 08/13/2010] [Accepted: 08/26/2010] [Indexed: 01/11/2023] Open
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Abdelwahid E, Rolland S, Teng X, Conradt B, Hardwick JM, White K. Mitochondrial involvement in cell death of non-mammalian eukaryotes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:597-607. [PMID: 20950655 DOI: 10.1016/j.bbamcr.2010.10.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 09/29/2010] [Accepted: 10/04/2010] [Indexed: 12/28/2022]
Abstract
Although mitochondria are essential organelles for long-term survival of eukaryotic cells, recent discoveries in biochemistry and genetics have advanced our understanding of the requirements for mitochondria in cell death. Much of what we understand about cell death is based on the identification of conserved cell death genes in Drosophila melanogaster and Caenorhabditis elegans. However, the role of mitochondria in cell death in these models has been much less clear. Considering the active role that mitochondria play in apoptosis in mammalian cells, the mitochondrial contribution to cell death in non-mammalian systems has been an area of active investigation. In this article, we review the current research on this topic in three non-mammalian models, C. elegans, Drosophila, and Saccharomyces cerevisiae. In addition, we discuss how non-mammalian models have provided important insight into the mechanisms of human disease as they relate to the mitochondrial pathway of cell death. The unique perspective derived from each of these model systems provides a more complete understanding of mitochondria in programmed cell death. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- Eltyeb Abdelwahid
- Cutaneous Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
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25
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Vaux DL. Apoptogenic factors released from mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:546-50. [PMID: 20713095 DOI: 10.1016/j.bbamcr.2010.08.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 07/30/2010] [Accepted: 08/03/2010] [Indexed: 11/27/2022]
Abstract
When cells kill themselves, they usually do so by activating mechanisms that have evolved specifically for that purpose. These mechanisms, which are broadly conserved throughout the metazoa, involve two processes: activation in the cytosol of latent cysteine proteases (termed caspases), and disruption of mitochondrial functions. These processes are linked in a number of different ways. While active caspases can cleave proteins in the mitochondrial outer membrane, and cleave and thereby activate certain pro-apoptotic members of the Bcl-2 family, proteins released from the mitochondria can trigger caspase activation and antagonise IAP family proteins. This review will focus on the pro-apoptotic molecules that are released from the mitochondria of cells endeavouring to kill themselves. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- David L Vaux
- La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Victoria 3086, Australia.
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Zhai Z, Fuchs AL, Lohmann I. Cellular analysis of newly identified Hox downstream genes in Drosophila. Eur J Cell Biol 2009; 89:273-8. [PMID: 20018403 DOI: 10.1016/j.ejcb.2009.11.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Hox genes code for conserved homeodomain transcription factors, which act as regional regulators for the specification of segmental identities along the anterior-posterior axis in all animals studied. They execute their function mainly through the activation or repression of their downstream genes. We have recently identified a large number of genes to be directly or indirectly targeted by Hox proteins through gene expression profiling in the model organism Drosophila. However, the cell-specific regulation of these downstream genes and the functional significance of the regulation are largely unknown. We have validated and functionally studied many of the newly identified downstream genes of the Hox proteins Deformed (Dfd) and Abdominal-B (Abd-B), and provide evidence that Hox proteins regulate a diverse group of downstream genes, from transcription factors to realisators with major and minor roles during morphogenesis.
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Affiliation(s)
- Zongzhao Zhai
- BIOQUANT Center, Cluster of Excellence - CellNetworks, Heidelberg, University of Heidelberg, Im Neuenheimer Feld 267, D-69120 Heidelberg, Germany
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27
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Simon CR, Moda LMR, Octacilio-Silva S, Anhezini L, Machado-Gitai LCH, Ramos RGP. Precise temporal regulation of roughest is required for correct salivary gland autophagic cell death in Drosophila. Genesis 2009; 47:492-504. [PMID: 19415632 DOI: 10.1002/dvg.20527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The Drosophila roughest (rst) locus encodes an immunoglobulin superfamily transmembrane glycoprotein implicated in a variety of embryonic and postembryonic developmental processes. Here we demonstrate a previously unnoticed role for this gene in the autophagic elimination of larval salivary glands during early pupal stages by showing that overexpression of the Rst protein ectodomain in early pupa leads to persistence of salivary glands up to at least 12 hours after head eversion, although with variable penetrance. The same phenotype is observed in individuals carrying the dominant regulatory allele rst(D), but not in loss of function alleles. Analysis of persistent glands at the ultrastructural level showed that programmed cell death starts at the right time but is arrested at an early stage of the process. Finally we describe the expression pattern and intracellular distribution of Rst in wild type and rst(D) mutants, showing that its downregulation in salivary glands at the beginning of pupal stage is an important factor in the correct implementation of the autophagic program of this tissue in space and time.
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Affiliation(s)
- Claudio R Simon
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Universidade de São Paulo, Ribeirão Preto-SP, Brazil
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Zhai Z, Stein MAS, Lohmann I. Expression of the apoptosis gene reaper in homeotic, segmentation and other mutants in Drosophila. Gene Expr Patterns 2009; 9:357-63. [PMID: 19602391 DOI: 10.1016/j.gep.2009.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 01/23/2009] [Accepted: 01/27/2009] [Indexed: 11/18/2022]
Abstract
Apoptosis is an essential process required for development and morphogenesis in metazoan organisms. The apoptosis pathway and cell death machinery have been extensively studied, but little is known how apoptosis genes are regulated in the course of development . In this study, we analyzed the transcriptional regulation of the pro-apoptotic gene reaper (rpr) by performing whole-mount in situ hybridization in embryos mutant for a number of transcription factor genes in Drosophila melanogaster. In sum, our data show that all factors studied have very specific temporal and spatial effects on rpr transcription . Thus, our results reinforce the concept that apoptosis is an essential process for morphogenesis and that apoptosis related genes very tight developmental factors identified in sculpting the morphology of various embryonic structures by modulating the apoptosis pathway.
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Affiliation(s)
- Zongzhao Zhai
- MPI for Development Biology, Department of Molecular Bilogy, AC I. Lohmann, 72076 Tübingen, Germany
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Lin N, Zhang C, Pang J, Zhou L. By design or by chance: cell death during Drosophila embryogenesis. Apoptosis 2009; 14:935-42. [PMID: 19466551 DOI: 10.1007/s10495-009-0360-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cell death plays an essential role during Drosophila embryogenesis. However, it remains an enigma as to what mechanisms determine (or select) the specific cells to be eliminated at a particular developmental stage. Is it mostly dependent on the lineage of the cell, signifying genetic predetermination, or is it due to the failure of a cell to compete for growth factors, which is more or less by chance? Recent developments in studying the molecular mechanism of cell death during Drosophila embryogenesis has provided much insight into our understanding of the relative importance of, and the interaction between, these two mechanisms in shaping the embryo.
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Affiliation(s)
- Nianwei Lin
- Department of Molecular Genetics and Microbiology, UF Shands Cancer Center, University of Florida, Gainesville, FL 32610-0232, USA
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30
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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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31
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Bryant B, Zhang Y, Zhang C, Santos CP, Clem RJ, Zhou L. A lepidopteran orthologue of reaper reveals functional conservation and evolution of IAP antagonists. INSECT MOLECULAR BIOLOGY 2009; 18:341-351. [PMID: 19523066 PMCID: PMC2926934 DOI: 10.1111/j.1365-2583.2009.00878.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Genetic studies in Drosophila melanogaster have revealed that inhibitor of apoptosis (IAP) proteins and IAP antagonists such as reaper play a pivotal role in controlling cell death in insects. Interestingly, although the sequences and structures of IAPs are highly conserved, the sequence of IAP antagonists diverged very rapidly during evolution, making their identification difficult. Using a customized bioinformatics approach, we identified an IAP antagonist, IAP-binding motif 1 (Ibm1), from the genome of the silkworm Bombyx mori. This is the first reaper/grim orthologue identified in a nondipteran insect. Previous analysis indicated that both Reaper and Grim induce cell death through their N-terminal IBM as well as the Grim_helix3 (GH3) domain. Functional studies indicated that Ibm1 binds to an IAP protein from B. mori, BmIAP1, and induces apoptosis in insect cells via the IAP-binding motif, a seven amino acid sequence that is highly conserved in all IAP antagonists. Interestingly, Ibm1 also contains a region that is a statistically significant match to the GH3 domain. Mutational analysis indicated that the GH3-like motif in Ibm1 has an important supportive role in IAP-antagonist function and can trigger cell death under certain conditions.
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Affiliation(s)
- Bart Bryant
- Division of Biology, Kansas State University, Manhattan, KS 66506-4901
| | - Yanping Zhang
- Department of Molecular Genetics and Microbiology & UF Shands Cancer Center, College of Medicine, University of Florida. Gainesville, FL 32610
| | - Can Zhang
- Department of Molecular Genetics and Microbiology & UF Shands Cancer Center, College of Medicine, University of Florida. Gainesville, FL 32610
| | - Carl P. Santos
- Department of Molecular Genetics and Microbiology & UF Shands Cancer Center, College of Medicine, University of Florida. Gainesville, FL 32610
| | - Rollie J. Clem
- Division of Biology, Kansas State University, Manhattan, KS 66506-4901
| | - Lei Zhou
- Department of Molecular Genetics and Microbiology & UF Shands Cancer Center, College of Medicine, University of Florida. Gainesville, FL 32610
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32
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Abstract
DNA damage or unprotected telomeres can trigger apoptosis via signaling pathways that directly sense abnormal DNA structures and activate the p53 transcription factor. We describe a p53-independent mechanism that acts in parallel to the canonical DNA damage response pathway in Drosophila to induce apoptosis after exposure to ionizing radiation. Following recovery from damage-induced cell cycle arrest, p53 mutant cells activate the JNK pathway and expression of the pro-apoptotic gene hid. Mutations in grp, a cell cycle checkpoint gene, and puc, a negative regulator of the JNK pathway, sensitize p53 mutant cells to ionizing radiation (IR)-induced apoptosis. Induction of chromosome aberrations by DNA damage generates cells with segmental aneuploidy and heterozygous for mutations in ribosomal protein genes. p53-independent apoptosis limits the formation of these aneuploid cells following DNA damage. We propose that reduced copy number of haploinsufficient genes following chromosome damage activates apoptosis and helps maintain genomic integrity.
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Xu D, Woodfield SE, Lee TV, Fan Y, Antonio C, Bergmann A. Genetic control of programmed cell death (apoptosis) in Drosophila. Fly (Austin) 2009; 3:78-90. [PMID: 19182545 DOI: 10.4161/fly.3.1.7800] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Programmed cell death, or apoptosis, is a highly conserved cellular process that has been intensively investigated in nematodes, flies and mammals. The genetic conservation, the low redundancy, the feasibility for high-throughput genetic screens and the identification of temporally and spatially regulated apoptotic responses make Drosophila melanogaster a great model for the study of apoptosis. Here, we review the key players of the cell death pathway in Drosophila and discuss their roles in apoptotic and non-apoptotic processes.
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Affiliation(s)
- Dongbin Xu
- The University of Texas MD Anderson Cancer Center, The Genes and Development Graduate Program, Department of Biochemistry and Molecular Biology, Houston, Texas 77030, USA
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Abstract
Drosophila is a powerful model system for the identification of cell death genes and understanding the role of cell death in development. In this chapter, we describe three methods typically used for the detection of cell death in Drosophila. The TUNEL and acridine orange methods are used to detect dead or dying cells in a variety of tissues. We focus on methods for the embryo and the ovary, but these techniques can be used on other tissues as well. The third method is the detection of genetic interactions by expressing cell death genes in the Drosophila eye.
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Tanaka-Matakatsu M, Xu J, Cheng L, Du W. Regulation of apoptosis of rbf mutant cells during Drosophila development. Dev Biol 2008; 326:347-56. [PMID: 19100727 DOI: 10.1016/j.ydbio.2008.11.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 11/19/2008] [Indexed: 12/19/2022]
Abstract
Inactivation of the retinoblastoma gene Rb leads to defects in cell proliferation, differentiation, or apoptosis, depending on specific cell or tissue types. To gain insights into the genes that can modulate the consequences of Rb inactivation, we carried out a genetic screen in Drosophila to identify mutations that affected apoptosis induced by inactivation of the Retinoblastoma-family protein (rbf) and identified a mutation that blocked apoptosis induced by rbf. We found this mutation to be a new allele of head involution defective (hid) and showed that hid expression is deregulated in rbf mutant cells in larval imaginal discs. We identified an enhancer that regulates hid expression in response to developmental cues as well as to radiation and demonstrated that this hid enhancer is directly repressed by RBF through an E2F binding site. These observations indicate that apoptosis of rbf mutant cells is mediated by an upregulation of hid. Finally, we showed that bantam, a miRNA that regulates hid translation, is expressed in the interommatidial cells in the larval eye discs and modulates the survival of rbf mutant cells.
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Affiliation(s)
- Miho Tanaka-Matakatsu
- Ben May Department for Cancer Research, the University of Chicago, Chicago, IL 60637, USA
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36
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Zhang Y, Lin N, Carroll PM, Chan G, Guan B, Xiao H, Yao B, Wu SS, Zhou L. Epigenetic blocking of an enhancer region controls irradiation-induced proapoptotic gene expression in Drosophila embryos. Dev Cell 2008; 14:481-93. [PMID: 18410726 DOI: 10.1016/j.devcel.2008.01.018] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 11/29/2007] [Accepted: 01/31/2008] [Indexed: 11/25/2022]
Abstract
Drosophila embryos are highly sensitive to gamma-ray-induced apoptosis at early but not later, more differentiated stages during development. Two proapoptotic genes, reaper and hid, are upregulated rapidly following irradiation. However, in post-stage-12 embryos, in which most cells have begun differentiation, neither proapoptotic gene can be induced by high doses of irradiation. Our study indicates that the sensitive-to-resistant transition is due to epigenetic blocking of the irradiation-responsive enhancer region (IRER), which is located upstream of reaper but is also required for the induction of hid in response to irradiation. This IRER, but not the transcribed regions of reaper/hid, becomes enriched for trimethylated H3K27/H3K9 and forms a heterochromatin-like structure during the sensitive-to-resistant transition. The functions of histone-modifying enzymes Hdac1(rpd3) and Su(var)3-9 and PcG proteins Su(z)12 and Polycomb are required for this process. Thus, direct epigenetic regulation of two proapoptotic genes controls cellular sensitivity to cytotoxic stimuli.
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Affiliation(s)
- Yanping Zhang
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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Abstract
Insects have made major contributions to understanding the regulation of cell death, dating back to the pioneering work of Lockshin and Williams on death of muscle cells during postembryonic development of Manduca. A physically smaller cousin of moths, the fruit fly Drosophila melanogaster, offers unique advantages for studying the regulation of cell death in response to different apoptotic stimuli in situ. Different signaling pathways converge in Drosophila to activate a common death program through transcriptional activation of reaper, hid and grim. Reaper-family proteins induce apoptosis by binding to and antagonizing inhibitor of apoptosis proteins (IAPs), which in turn inhibit caspases. This switch from life to death relies extensively on targeted degradation of cell death proteins by the ubiquitin-proteasome pathway. Drosophila IAP-1 (Diap1) functions as an E3-ubiquitin ligase to protect cells from unwanted death by promoting the degradation of the initiator caspase Dronc. However, in response to apoptotic signals, Reaper-family proteins are produced, which promote the auto-ubiquitination and degradation of Diap1, thereby removing the 'brakes on death' in cells that are doomed to die. More recently, several other ubiquitin pathway proteins were found to play important roles for caspase regulation, indicating that the control of cell survival and death relies extensively on targeted degradation by the ubiquitin-proteasome pathway.
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The interaction of DIAP1 with dOmi/HtrA2 regulates cell death in Drosophila. Cell Death Differ 2008; 15:1073-83. [PMID: 18259196 DOI: 10.1038/cdd.2008.19] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Mitochondrial proteins such as cytochrome c, Smac/DIABLO and Omi/HtrA2 play important roles in the cell death pathways of mammalian cells. In Drosophila, the role of mitochondria in cell death is less clear. Here, we report the identification and characterization of the Drosophila ortholog of human Omi/HtrA2. We show that Drosophila Omi/HtrA2 is imported into the mitochondria where it undergoes proteolytic maturation to yield two isoforms, dOmi-L and dOmi-S. dOmi-L contains a canonical N-terminal IAP-binding motif (AVVS), whereas dOmi-S contains a distinct N-terminal motif (SKMT). DIAP1 was able to bind to both isoforms via its BIR1 and BIR2 domains. This resulted in cleavage of the linker region of DIAP1 between the BIR1 and BIR2 domains and further degradation of the BIR1 domain by the proteolytic activity of dOmi. The binding of DIAP1 to dOmi also resulted in DIAP1-mediated polyubiquitination of dOmi, suggesting that DIAP1 could target dOmi for proteasomal degradation. Consistent with this, expression of DIAP1 in Drosophila eye discs protected them from dOmi-induced eye ablation, indicating that DIAP1 plays an important role in protecting cells from the potentially lethal effects of dOmi. The ability of IAPs to bind to and ubiquitinate mitochondrial proteins such as dOmi may be a key conserved function to counterbalance the lethal effects of these proteins if accidentally released into the cytosol.
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Peterson JS, Bass BP, Jue D, Rodriguez A, Abrams JM, McCall K. Noncanonical cell death pathways act during Drosophila oogenesis. Genesis 2007; 45:396-404. [PMID: 17506088 DOI: 10.1002/dvg.20306] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Programmed cell death (PCD) is a highly conserved process that occurs during development and in response to adverse conditions. In Drosophila, most PCDs require the genes within the H99 deficiency, the adaptor molecule Ark, and caspases. Here we investigate 10 cell death genes for their potential roles in two distinct types of PCD that occur in oogenesis: developmental nurse cell PCD and starvation-induced PCD. Most of the genes investigated were found to have little effect on late stage developmental PCD in oogenesis, although ark mutants showed a partial inhibition. Mid-stage starvation-induced germline PCD was found to be independent of the upstream activators and ark although it requires caspases, suggesting an apoptosome-independent mechanism of caspase activation in mid-oogenesis. These results indicate that novel pathways must control PCD in the ovary.
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Affiliation(s)
- Jeanne S Peterson
- Department of Biology, Boston University, Boston, Massachusetts 02115, USA
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40
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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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Sato K, Hayashi Y, Ninomiya Y, Shigenobu S, Arita K, Mukai M, Kobayashi S. Maternal Nanos represses hid/skl-dependent apoptosis to maintain the germ line in Drosophila embryos. Proc Natl Acad Sci U S A 2007; 104:7455-60. [PMID: 17449640 PMCID: PMC1854842 DOI: 10.1073/pnas.0610052104] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nanos (Nos) is an evolutionarily conserved protein essential for the survival of primordial germ cells. In Drosophila, maternal Nos partitions into pole cells and suppresses apoptosis to permit proper germ-line development. However, how this critical event is regulated by Nos has remained elusive. Here, we report that Nos represses apoptosis of pole cells by suppressing translation of head involution defective (hid), a member of the RHG gene family that is required for Caspase activation. In addition, we demonstrate that hid acts in concert with another RHG gene, sickle (skl), to induce apoptosis. Expression of skl is induced in pole cells by maternal tao-1, a ste20-like serine/threonine kinase. Tao-1-dependent skl expression is required to potentiate hid activity. However, skl expression is largely suppressed in normal pole cells. Once the pole cells lack maternal Nos, Tao-1-dependent skl expression is fully activated, suggesting that skl expression is also restricted by Nos. These findings provide the first evidence that the germ line is maintained through the regulated expression of RHG genes.
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Affiliation(s)
- Kimihiro Sato
- *Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Yoshiki Hayashi
- *Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Yuichi Ninomiya
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama 350-1241, Japan; and
| | - Shuji Shigenobu
- *Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Kayo Arita
- *Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Masanori Mukai
- *Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Satoru Kobayashi
- *Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki 444-8787, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Honcho, Kawaguchi 332-0012, Japan
- To whom correspondence should be addressed. E-mail:
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Abstract
Cell death plays many roles during development, in the adult, and in the genesis of many pathological states. Much of this death is apoptotic in nature and requires the activity of members of the caspase family of proteases. It is now possible uniquely in Drosophila to carry out genetic screens for genes that determine the fate-life or death-of any population of cells during development and adulthood. This, in conjunction with the ability to obtain biochemical quantities of material, has made Drosophila a useful organism for exploring the mechanisms by which apoptosis is carried out and regulated. This review summarizes our knowledge of caspase-dependent cell death in Drosophila and compares that knowledge with what is known in worms and mammals. We also discuss the significance of recent work showing that a number of key cell death activators also play nonapoptotic roles. We highlight opportunities and outstanding questions along the way.
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Affiliation(s)
- Bruce A Hay
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
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Liu W, Silverstein AM, Shu H, Martinez B, Mumby MC. A functional genomics analysis of the B56 isoforms of Drosophila protein phosphatase 2A. Mol Cell Proteomics 2006; 6:319-32. [PMID: 17121811 DOI: 10.1074/mcp.m600272-mcp200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the B56 family of protein phosphatase 2A (PP2A) regulatory subunits play crucial roles in Drosophila cell survival. Distinct functions of two B56 subunits were investigated using a combination of RNA interference, DNA microarrays, and proteomics. RNA interference-mediated knockdown of the B56-1 subunit (PP2A-B') but not the catalytic (mts) or B56-2 subunit (wdb) of PP2A resulted in increased expression of the apoptotic inducers reaper and sickle. Co-knockdown of B56-1 with reaper, but not with sickle, reduced the apoptosis caused by depletion of the B56 subunits. Two-dimensional gel electrophoresis and mass spectrometry identified proteins modified in cells depleted of PP2A subunits. These included generation of caspase-dependent cleavage products, increases in protein abundance, and covalent modifications. Results suggested that up-regulation of the ribosome-associated protein stubarista can serve as a sensitive marker of apoptosis. Up-regulation of transcripts for multiple glutathione transferases and other proteins suggested that loss of PP2A affected pathways involved in the response to oxidative stress. Knockdown of PP2A elevated basal JNK activity and substantially decreased activation of ERK in response to oxidative stress. The results reveal that the B56-containing isoform of PP2A functions within multiple signaling pathways, including those that regulate expression of reaper and the response to oxidative stress, thus promoting cell survival in Drosophila.
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Affiliation(s)
- Wei Liu
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
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44
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Muro I, Berry DL, Huh JR, Chen CH, Huang H, Yoo SJ, Guo M, Baehrecke EH, Hay BA. The Drosophila caspase Ice is important for many apoptotic cell deaths and for spermatid individualization, a nonapoptotic process. Development 2006; 133:3305-15. [PMID: 16887831 DOI: 10.1242/dev.02495] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Caspase family proteases play important roles in the regulation of apoptotic cell death. Initiator caspases are activated in response to death stimuli, and they transduce and amplify these signals by cleaving and thereby activating effector caspases. In Drosophila, the initiator caspase Nc (previously Dronc) cleaves and activates two short-prodomain caspases, Dcp-1 and Ice (previously Drice), suggesting these as candidate effectors of Nc killing activity. dcp-1-null mutants are healthy and possess few defects in normally occurring cell death. To explore roles for Ice in cell death, we generated and characterized an Ice null mutant. Animals lacking Ice show a number of defects in cell death, including those that occur during embryonic development, as well as during formation of adult eyes, arista and wings. Ice mutants exhibit subtle defects in the destruction of larval tissues, and do not prevent destruction of salivary glands during metamorphosis. Cells from Ice animals are also markedly resistant to several stresses, including X-irradiation and inhibition of protein synthesis. Mutations in Ice also suppress cell death that is induced by expression of Rpr, Wrinkled (previously Hid) and Grim. These observations demonstrate that Ice plays an important non-redundant role as a cell death effector. Finally, we demonstrate that Ice participates in, but is not absolutely required for, the non-apoptotic process of spermatid differentiation.
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Affiliation(s)
- Israel Muro
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA.
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45
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Kolesnikova TD, Andreeva EN, Pindyurin AV, Ananko NG, Belyakin SN, Shloma VV, Yurlova AA, Makunin IV, Pokholkova GV, Volkova EI, Zarutskaya EA, Kokoza EB, Semeshin VF, Belyaeva ES, Zhimulev IF. Contribution of the SuUR gene to the organization of epigenetically repressed regions of Drosophila melanogaster chromosomes. RUSS J GENET+ 2006. [DOI: 10.1134/s1022795406080011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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46
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Means JC, Muro I, Clem RJ. Lack of involvement of mitochondrial factors in caspase activation in a Drosophila cell-free system. Cell Death Differ 2006; 13:1222-34. [PMID: 16322754 PMCID: PMC2575646 DOI: 10.1038/sj.cdd.4401821] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Although mitochondrial proteins play well-defined roles in caspase activation in mammalian cells, the role of mitochondrial factors in caspase activation in Drosophila is unclear. Using cell-free extracts, we demonstrate that mitochondrial factors play no apparent role in Drosophila caspase activation. Cytosolic extract from apoptotic S2 cells, in which caspases were inhibited, induced caspase activation in cytosolic extract from normal S2 cells. Mitochondrial extract did not activate caspases, nor did it influence caspase activation by cytosolic extract. Silencing of Hid, Reaper, or Grim reduced caspase activation by apoptotic cell extract. Furthermore, a peptide representing the amino terminus of Hid was sufficient to activate caspases in cytosolic extract, and this activity was not enhanced by addition of mitochondria or mitochondrial lysate. The Hid peptide also induced apoptosis when introduced into S2 cells. These results suggest that caspase activation in Drosophila is regulated solely by cytoplasmic factors and does not involve any mitochondrial factors.
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Affiliation(s)
- John C. Means
- Molecular, Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506
| | | | - Rollie J. Clem
- Molecular, Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506
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Vazquez-Pianzola P, Hernández G, Suter B, Rivera-Pomar R. Different modes of translation for hid, grim and sickle mRNAs in Drosophila. Cell Death Differ 2006; 14:286-95. [PMID: 16794603 DOI: 10.1038/sj.cdd.4401990] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Protein synthesis is inhibited during apoptosis. However, the translation of many mRNAs still proceeds driven by internal ribosome entry sites (IRESs). Here we show that the 5'UTR of hid and grim mRNAs promote translation of uncapped-mRNA reporters in cell-free embryonic extracts and that hid and grim mRNA 5'UTRs drive IRES-mediated translation. The translation of capped-reporters proceeds in the presence of cap competitor and in extracts where cap-dependent translation is impaired. We show that the endogenous hid and grim mRNAs are present in polysomes of heat-shocked embryos, indicating that cap recognition is not required for translation. In contrast, sickle mRNA is translated in a cap-dependent manner in all these assays. Our results show that IRES-dependent initiation may play a role in the translation of Drosophila proapoptotic genes and suggest a variety of regulatory pathways.
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Affiliation(s)
- P Vazquez-Pianzola
- Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Biologie, Am Fassberg 11, Göttingen, Germany
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48
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Choi YJ, Lee G, Park JH. Programmed cell death mechanisms of identifiable peptidergic neurons in Drosophila melanogaster. Development 2006; 133:2223-32. [PMID: 16672345 DOI: 10.1242/dev.02376] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The molecular basis of programmed cell death (PCD) of neurons during early metamorphic development of the central nervous system (CNS) in Drosophila melanogaster are largely unknown, in part owing to the lack of appropriate model systems. Here, we provide evidence showing that a group of neurons (vCrz) that express neuropeptide Corazonin (Crz) gene in the ventral nerve cord of the larval CNS undergo programmed death within 6 hours of the onset of metamorphosis. The death was prevented by targeted expression of caspase inhibitor p35, suggesting that these larval neurons are eliminated via a caspase-dependent pathway. Genetic and transgenic disruptions of ecdysone signal transduction involving ecdysone receptor-B (EcR-B) isoforms suppressed vCrz death, whereas transgenic re-introduction of either EcR-B1 or EcR-B2 isoform into the EcR-B-null mutant resumed normal death. Expression of reaper in vCrz neurons and suppression of vCrz-cell death in a reaper-null mutant suggest that reaper functions are required for the death, while no apparent role was found for hid or grim as a death promoter. Our data further suggest that diap1 does not play a role as a central regulator of the PCD of vCrz neurons. Significant delay of vCrz-cell death was observed in mutants that lack dronc or dark functions, indicating that formation of an apoptosome is necessary, but not sufficient, for timely execution of the death. These results suggest that activated ecdysone signaling determines precise developmental timing of the neuronal degeneration during early metamorphosis, and that subsequent reaper-mediated caspase activation occurs through a novel DIAP1-independent pathway.
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Affiliation(s)
- Youn-Jeong Choi
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, 37996, USA
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49
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Akdemir F, Farkas R, Chen P, Juhasz G, Medved'ová L, Sass M, Wang L, Wang X, Chittaranjan S, Gorski SM, Rodriguez A, Abrams JM. Autophagy occurs upstream or parallel to the apoptosome during histolytic cell death. Development 2006; 133:1457-65. [PMID: 16540507 DOI: 10.1242/dev.02332] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Histolysis refers to a widespread disintegration of tissues that is morphologically distinct from apoptosis and often associated with the stimulation of autophagy. Here, we establish that a component of the apoptosome, and pivotal regulator of apoptosis, is also required for histolytic cell death. Using in vivo and ex vivo assays, we demonstrate a global apoptogenic requirement for dark, the fly ortholog of Apaf1, and show that a required focus of dark(-) organismal lethality maps to the central nervous system. We further demonstrate that the Dark protein itself is a caspase substrate and find that alterations of this cleavage site produced the first hypermorphic point mutation within the Apaf1/Ced-4 gene family. In a model of ;autophagic cell death', dark was essential for histolysis but dispensable for characteristic features of the autophagic program, indicating that the induction of autophagy occurs upstream or parallel to histolytic cell death. These results demonstrate that stimulation of autophagy per se is not a ;killing event' and, at the same time, establish that common effector pathways, regulated by the apoptosome, can underlie morphologically distinct forms of programmed cell death.
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Affiliation(s)
- Fatih Akdemir
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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50
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Leaman D, Chen PY, Fak J, Yalcin A, Pearce M, Unnerstall U, Marks DS, Sander C, Tuschl T, Gaul U. Antisense-mediated depletion reveals essential and specific functions of microRNAs in Drosophila development. Cell 2005; 121:1097-108. [PMID: 15989958 DOI: 10.1016/j.cell.2005.04.016] [Citation(s) in RCA: 262] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Revised: 01/28/2005] [Accepted: 04/14/2005] [Indexed: 12/21/2022]
Abstract
MicroRNAs are small noncoding RNAs that control gene function posttranscriptionally through mRNA degradation or translational inhibition. Much has been learned about the processing and mechanism of action of microRNAs, but little is known about their biological function. Here, we demonstrate that injection of 2'O-methyl antisense oligoribonucleotides into early Drosophila embryos leads to specific and efficient depletion of microRNAs and thus permits systematic loss-of-function analysis in vivo. Twenty-five of the forty-six embryonically expressed microRNAs show readily discernible defects; pleiotropy is moderate and family members display similar yet distinct phenotypes. Processes under microRNA regulation include cellularization and patterning in the blastoderm, morphogenesis, and cell survival. The largest microRNA family in Drosophila (miR-2/6/11/13/308) is required for suppressing embryonic apoptosis; this is achieved by differential posttranscriptional repression of the proapoptotic factors hid, grim, reaper, and sickle. Our findings demonstrate that microRNAs act as specific and essential regulators in a wide range of developmental processes.
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Affiliation(s)
- Dan Leaman
- Laboratory of Developmental Neurogenetics, Rockefeller University, 1230 York Ave, New York, New York 10021, USA
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