251
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Pankotai T, Komonyi O, Bodai L, Ujfaludi Z, Muratoglu S, Ciurciu A, Tora L, Szabad J, Boros I. The homologous Drosophila transcriptional adaptors ADA2a and ADA2b are both required for normal development but have different functions. Mol Cell Biol 2005; 25:8215-27. [PMID: 16135810 PMCID: PMC1234310 DOI: 10.1128/mcb.25.18.8215-8227.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
In Drosophila and several other metazoan organisms, there are two genes that encode related but distinct homologs of ADA2-type transcriptional adaptors. Here we describe mutations of the two Ada2 genes of Drosophila melanogaster. By using mutant Drosophila lines, which allow the functional study of individual ADA2s, we demonstrate that both Drosophila Ada2 genes are essential. Ada2a and Ada2b null homozygotes are late-larva and late-pupa lethal, respectively. Double mutants have a phenotype identical to that of the Ada2a mutant. The overproduction of ADA2a protein from transgenes cannot rescue the defects resulting from the loss of Ada2b, nor does complementation work vice versa, indicating that the two Ada2 genes of Drosophila have different functions. An analysis of germ line mosaics generated by pole-cell transplantation revealed that the Ada2a function (similar to that reported for Ada2b) is required in the female germ line. A loss of the function of either of the Ada2 genes interferes with cell proliferation. Interestingly, the Ada2b null mutation reduces histone H3 K14 and H3 K9 acetylation and changes TAF10 localization, while the Ada2a null mutation does not. Moreover, the two ADA2s are differently required for the expression of the rosy gene, involved in eye pigment production, and for Dmp53-mediated apoptosis. The data presented here demonstrate that the two genes encoding homologous transcriptional adaptor ADA2 proteins in Drosophila are both essential but are functionally distinct.
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Affiliation(s)
- Tibor Pankotai
- Department of Genetics and Molecular Biology, University of Szeged, Közép Fasor 52, H-6726 Szeged, Hungary
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252
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Affiliation(s)
- Alea A Mills
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
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253
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David-Pfeuty T. The flexible evolutionary anchorage-dependent Pardee's restriction point of mammalian cells: how its deregulation may lead to cancer. Biochim Biophys Acta Rev Cancer 2005; 1765:38-66. [PMID: 16219425 DOI: 10.1016/j.bbcan.2005.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 08/24/2005] [Accepted: 08/26/2005] [Indexed: 12/12/2022]
Abstract
Living cells oscillate between the two states of quiescence and division that stand poles apart in terms of energy requirements, macromolecular composition and structural organization and in which they fulfill dichotomous activities. Division is a highly dynamic and energy-consuming process that needs be carefully orchestrated to ensure the faithful transmission of the mother genotype to daughter cells. Quiescence is a low-energy state in which a cell may still have to struggle hard to maintain its homeostasis in the face of adversity while waiting sometimes for long periods before finding a propitious niche to reproduce. Thus, the perpetuation of single cells rests upon their ability to elaborate robust quiescent and dividing states. This led yeast and mammalian cells to evolve rigorous Start [L.H. Hartwell, J. Culotti, J. Pringle, B.J. Reid, Genetic control of the cell division cycle in yeast, Science 183 (1974) 46-51] and restriction (R) points [A.B. Pardee, A restriction point for control of normal animal cell proliferation, Proc. Natl. Acad. Sci. U. S. A. 71 (1974) 1286-1290], respectively, that reduce deadly interferences between the two states by enforcing their temporal insulation though still enabling a rapid transition from one to the other upon an unpredictable change in their environment. The constitutive cells of multi-celled organisms are extremely sensitive in addition to the nature of their adhering support that fluctuates depending on developmental stage and tissue specificity. Metazoan evolution has entailed, therefore, the need for exceedingly flexible anchorage-dependent R points empowered to assist cells in switching between quiescence and division at various times, places and conditions in the same organism. Programmed cell death may have evolved concurrently in specific contexts unfit for the operation of a stringent R point that increase the risk of deadly interferences between the two states (as it happens notably during development). But, because of their innate flexibility, anchorage-dependent R points have also the ability to readily adjust to a changing structural context so as to give mutated cells a chance to reproduce, thereby encouraging tumor genesis. The Rb and p53 proteins, which are regulated by the two products of the Ink4a-Arf locus [C.J. Sherr, The INK4a/ARF network in tumor suppression, Nat. Rev., Mol. Cell Biol. 2 (2001) 731-737], govern separable though interconnected pathways that cooperate to restrain cyclin D- and cyclin E-dependent kinases from precipitating untimely R point transit. The expression levels of the Ink4a and Arf proteins are especially sensitive to changes in cellular shape and adhesion that entirely remodel at the time when cells shift between quiescence and division. The Arf proteins further display an extremely high translational sensitivity and can activate the p53 pathway to delay R point transit, but, only when released from the nucleolus, 'an organelle formed by the act of building a ribosome' [T. Mélèse, Z. Xue, The nucleolus: an organelle formed by the act of building a ribosome, Curr. Opin. Cell Biol. 7 (1995) 319-324]. In this way, the Ink4a/Rb and Arf/p53 pathways emerge as key regulators of anchorage-dependent R point transit in mammalian cells and their deregulation is, indeed, a rule in human cancers. Thus, by selecting the nucleolus to mitigate cell cycle control by the Arf proteins, mammalian cells succeeded in forging a highly flexible R point enabling them to match cell division with a growth rate imposed by factors controlling nucleolar assembling, such as nutrients and adhesion. It is noteworthy that nutrient control of critical size at Start in budding yeast has been shown recently to be governed by a nucleolar protein interaction network [P. Jorgensen, J.L. Nishikawa, B.-J. Breitkreutz, M. Tyers, Systematic identification of pathways that couple cell growth and division in yeast, Science 297 (2002) 395-400].
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Affiliation(s)
- Thérèse David-Pfeuty
- UMR 146 du CNRS, Institut Curie-Recherche, Bâtiment 110, Centre Universitaire, 91405 Orsay, France.
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254
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Terashima J, Bownes M. A microarray analysis of genes involved in relating egg production to nutritional intake in Drosophila melanogaster. Cell Death Differ 2005; 12:429-40. [PMID: 15776001 DOI: 10.1038/sj.cdd.4401587] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Egg chambers of Drosophila are reabsorbed under conditions of nutritional shortage by inducing apoptosis at stages 8 and 9, midway through oogenesis. Nutritional shortage leads to an increase in ecdysone concentration in flies. Apoptosis at stage 8/9 is also induced by 20-hydroxyecdysone injection into the females maintained with adequate nutrition. The expression pattern in the ovary of some ecdysone response genes, E75A, BR-C, is different according to the nutritional environment and the overexpression of these genes induces apoptosis. Apoptosis is suppressed by Juvenile hormone analog treatment of females under nutritional shortage. We predict nutritional and stress response genes control hormone levels and the increase in ecdysone concentration in the flies following starvation induces the ovarian apoptosis. We therefore used a microarray approach to identify the genes involved in receiving the nutritional signal from the environment and translating it in the ovary, thus initiating and executing apoptosis.
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Affiliation(s)
- J Terashima
- Institute of Cell Biology, School of Biology, University of Edinburgh, UK.
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255
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Bourdon JC, Fernandes K, Murray-Zmijewski F, Liu G, Diot A, Xirodimas DP, Saville MK, Lane DP. p53 isoforms can regulate p53 transcriptional activity. Genes Dev 2005; 19:2122-37. [PMID: 16131611 PMCID: PMC1221884 DOI: 10.1101/gad.1339905] [Citation(s) in RCA: 589] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The recently discovered p53-related genes, p73 and p63, express multiple splice variants and N-terminally truncated forms initiated from an alternative promoter in intron 3. To date, no alternative promoter and multiple splice variants have been described for the p53 gene. In this study, we show that p53 has a gene structure similar to the p73 and p63 genes. The human p53 gene contains an alternative promoter and transcribes multiple splice variants. We show that p53 variants are expressed in normal human tissue in a tissue-dependent manner. We determine that the alternative promoter is conserved through evolution from Drosophila to man, suggesting that the p53 family gene structure plays an essential role in the multiple activities of the p53 family members. Consistent with this hypothesis, p53 variants are differentially expressed in human breast tumors compared with normal breast tissue. We establish that p53beta can bind differentially to promoters and can enhance p53 target gene expression in a promoter-dependent manner, while Delta133p53 is dominant-negative toward full-length p53, inhibiting p53-mediated apoptosis. The differential expression of the p53 isoforms in human tumors may explain the difficulties in linking p53 status to the biological properties and drug sensitivity of human cancer.
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MESH Headings
- Alternative Splicing
- Animals
- Apoptosis/genetics
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Cell Line, Tumor
- Drosophila/genetics
- Evolution, Molecular
- Gene Expression Regulation, Neoplastic
- Genes, Insect
- Genes, Reporter
- Genes, p53
- Genetic Variation
- HT29 Cells
- Humans
- Introns
- Luciferases/metabolism
- Promoter Regions, Genetic
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic
- Tumor Suppressor Protein p53/chemistry
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- Jean-Christophe Bourdon
- Department of Surgery, Cancer Research-UK Cell Transformation Research Group, University of Dundee, Ninewells Hospital, Scotland, UK.
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256
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Greenwood J, Gautier J. From oogenesis through gastrulation: developmental regulation of apoptosis. Semin Cell Dev Biol 2005; 16:215-24. [PMID: 15797832 DOI: 10.1016/j.semcdb.2004.12.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Apoptosis is a mechanism employed by multicellular organisms throughout development as a means of eliminating damaged or otherwise unwanted cells. From oogenesis through fertilization and gastrulation, organisms use an array of cell- and tissue-specific mechanisms to regulate the apoptotic program in response to stress or developmental cues. Since cell death regulation is tightly interwoven with cell cycle and checkpoint controls, and embryos of the fly, fish and frog exhibit unique embryonic cell cycle regulation, it is of great interest to understand how early embryos coordinate these cellular functions.
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Affiliation(s)
- Jessica Greenwood
- Integrated Program in Cellular, Molecular, and Biophysical Studies, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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257
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McEwen DG, Peifer M. Puckered, a Drosophila MAPK phosphatase, ensures cell viability by antagonizing JNK-induced apoptosis. Development 2005; 132:3935-46. [PMID: 16079158 DOI: 10.1242/dev.01949] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
MAPK phosphatases (MKPs) are important negative regulators of MAPKs in vivo, but ascertaining the role of specific MKPs is hindered by functional redundancy in vertebrates. Thus, we characterized MKP function by examining the function of Puckered (Puc), the sole Drosophila Jun N-terminal kinase (JNK)-specific MKP, during embryonic and imaginal disc development. We demonstrate that Puc is a key anti-apoptotic factor that prevents apoptosis in epithelial cells by restraining basal JNK signaling. Furthermore, we demonstrate that JNK signaling plays an important role in gamma-irradiation-induced apoptosis, and examine how JNK signaling fits into the circuitry regulating this process. Radiation upregulates both JNK activity and puc expression in a p53-dependent manner, and apoptosis induced by loss of Puc can be suppressed by p53 inactivation. JNK signaling acts upstream of both Reaper and effector caspases. Finally, we demonstrate that JNK signaling directs normal developmentally regulated apoptotic events. However, if cell death is prevented, JNK activation can trigger tissue overgrowth. Thus, MKPs are key regulators of the delicate balance between proliferation, differentiation and apoptosis during development.
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Affiliation(s)
- Donald G McEwen
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA.
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258
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Waldhuber M, Emoto K, Petritsch C. The Drosophila caspase DRONC is required for metamorphosis and cell death in response to irradiation and developmental signals. Mech Dev 2005; 122:914-27. [PMID: 15922568 DOI: 10.1016/j.mod.2005.04.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2004] [Revised: 03/22/2005] [Accepted: 04/06/2005] [Indexed: 12/28/2022]
Abstract
Cell death is essential for eliminating excess cells during development as well as removing damaged cells. While multiple conserved apoptosis pathways involving different cascades of caspases, which are cysteine proteases, have been identified, their regulation in the context of a developing organism is not very well understood. Expression of the Drosophila caspase-9 homolog, DRONC, can be induced by ecdysone, a steroid hormone, which induces metamorphosis. To elucidate the functional role of DRONC during metamorphosis and for cell death during development we have generated and analyzed two loss-of-function alleles of DRONC. We report that DRONC is required for developmentally induced neuroblast cell death and apoptosis in response to X irradiation. DRONC mutants show reduced pupariation even in the presence of high levels of ecdysone and impaired cell death of larval midgut. The levels of ecdysone-inducible transcripts such as E75A and Reaper (Rpr) are normal in the absence of DRONC, suggesting that DRONC acts downstream of these genes. In addition, Reaper and Grim, but not Hid induced apoptosis is sensitive to a reduction of DRONC levels. Our study places DRONC at a central point of convergence for multiple cell death pathways and for the ecdysone pathway regulating metamorphosis.
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Affiliation(s)
- Markus Waldhuber
- Laboratory for Molecular Biology, Gene Center, Ludwig-Maximilian-University Munich, Feodor-Lynen-Strasse 25, 81377, Munich, Germany
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259
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Lee SB, Park J, Jung JU, Chung J. Nef induces apoptosis by activating JNK signaling pathway and inhibits NF-kappaB-dependent immune responses in Drosophila. J Cell Sci 2005; 118:1851-9. [PMID: 15827086 DOI: 10.1242/jcs.02312] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) nef gene encodes a 27-kDa protein that plays a crucial role during AIDS pathogenesis, but its exact functional mechanism has not been fully elucidated and remains controversial. The present study illuminated the in vivo functions of Nef using Drosophila, in which genetic analyses can be conveniently conducted. Using Drosophila transgenic lines for wild-type Nef, we demonstrated that Nef is not involved in the regulation of cell proliferation but rather specifically induces caspase-dependent apoptosis in wings in a cell-autonomous manner. Interestingly, myristoylation-defective Nef completely failed to induce the apoptotic wing phenotypes, consistent with previous reports demonstrating a crucial role for membrane localization of Nef in vivo. Further genetic and immunohistochemical studies revealed that Nef-dependent JNK activation is responsible for apoptosis. Furthermore, we found that ectopic expression of Nef inhibits Drosophila innate immune responses including Relish NF-kappaB activation with subsequent induction of an antimicrobial peptide, diptericin. The in vivo functions of Nef in Drosophila are highly consistent with those found in mammals and so we propose that Nef regulates evolutionarily highly conserved signaling molecules of the JNK and NF-kappaB signaling pathways at the plasma membrane, and consequently modulates apoptosis and immune responses in HIV target cells.
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Affiliation(s)
- Sung Bae Lee
- National Creative Research Initiatives Center for Cell Growth Regulation and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea
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260
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Huyen Y, Jeffrey PD, Derry WB, Rothman JH, Pavletich NP, Stavridi ES, Halazonetis TD. Structural differences in the DNA binding domains of human p53 and its C. elegans ortholog Cep-1. Structure 2005; 12:1237-43. [PMID: 15242600 DOI: 10.1016/j.str.2004.05.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Revised: 05/10/2004] [Accepted: 05/10/2004] [Indexed: 11/16/2022]
Abstract
The DNA binding domains of human p53 and Cep-1, its C. elegans ortholog, recognize essentially identical DNA sequences despite poor sequence similarity. We solved the three-dimensional structure of the Cep-1 DNA binding domain in the absence of DNA and compared it to that of human p53. The two domains have similar overall folds. However, three loops, involved in DNA and Zn binding in human p53, contain small alpha helices in Cep-1. The alpha helix in loop L3 of Cep-1 orients the side chains of two conserved arginines toward DNA; in human p53, both arginines are mutation hotspots, but only one contacts DNA. The alpha helix in loop L1 of Cep-1 repositions the entire loop, making it unlikely for residues of this loop to contact bases in the major groove of DNA, as occurs in human p53. Thus, during evolution there have been considerable changes in the structure of the p53 DNA binding domain.
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261
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Besson MT, Ré DB, Moulin M, Birman S. High Affinity Transport of Taurine by the Drosophila Aspartate Transporter dEAAT2. J Biol Chem 2005; 280:6621-6. [PMID: 15611131 DOI: 10.1074/jbc.m412440200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Excitatory amino acid transporters (EAATs) are structurally related plasma membrane proteins known to mediate the Na(+)/K(+)-dependent uptake of the amino acids l-glutamate and dl-aspartate. In the nervous system, these proteins contribute to the clearance of glutamate from the synaptic cleft and maintain excitatory amino acid concentrations below excitotoxic levels. Two homologues exist in Drosophila melanogaster, dEAAT1 and dEAAT2, which are specifically expressed in the nervous tissue. We previously reported that dEAAT2 shows unique substrate discrimination as it mediates high affinity transport of aspartate but not glutamate. We now show that dEAAT2 can also transport the amino acid taurine with high affinity, a property that is not shared by two other transporters of the same family, Drosophila dEAAT1 and human hEAAT2. Taurine transport by dEAAT2 was efficiently blocked by an EAAT antagonist but not by inhibitors of the structurally unrelated mammalian taurine transporters. Taurine and aspartate are transported with similar K(m) and relative efficacy and behave as mutually competitive inhibitors. dEAAT2 can mediate either net uptake or the heteroexchange of its two substrates, both being dependent on the presence of Na(+) ions in the external medium. Interestingly, heteroexchange only occurs in one preferred substrate orientation, i.e. with taurine transported inwards and aspartate outwards, suggesting a mechanism of transinhibition of aspartate uptake by intracellular taurine. Therefore, dEAAT2 is actually an aspartate/taurine transporter. Further studies of this protein are expected to shed light on the role of taurine as a candidate neuromodulator and cell survival factor in the Drosophila nervous system.
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Affiliation(s)
- Marie Thérèse Besson
- Laboratoire de Génétique et Physiologie du Développement, UMR 6545 CNRS-Université de la Méditerranée, Developmental Biology Institute of Marseille, Campus de Luminy, Case 907, 13288 Marseille Cedex 9, France
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262
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Mather A, Rakgotho M, Ntwasa M. SNAMA, a novel protein with a DWNN domain and a RING finger-like motif: a possible role in apoptosis. ACTA ACUST UNITED AC 2005; 1727:169-76. [PMID: 15733535 DOI: 10.1016/j.bbaexp.2005.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Revised: 10/14/2004] [Accepted: 01/11/2005] [Indexed: 10/25/2022]
Abstract
We have characterized SNAMA a hitherto uncharacterized Drosophila protein that appears to play a role in apoptosis. SNAMA (something that sticks like glue) is a 1231 amino acid protein with a conserved 76 residue N-terminal domain called Domain With No Name (DWNN). The DWNN domain was first identified in cytotoxic T Cell-resistant CHO cells using promoter trap mutagenesis to screen for genes involved in apoptosis. Subsequently, this domain was identified in other eukaryotic organisms including animals and plants. The SNAMA transcript is abundant early in embryogenesis but reduced in older embryos and in adult males and females. Human and mouse homologues of SNAMA are known to bind to p53 and to the retinoblastoma protein (Rb) suggesting a role in transcriptional regulation and cell cycle control. We took advantage of a P-element insertion line in which the P-element is inserted in the first intron, to investigate the biological function of the gene. These mutants are lethal when homozygous. Apoptosis appears early during embryogenesis and is observed virtually throughout the gastrula. The DWNN domain has a ubiquitin-like fold and may interact with a subset of cellular proteins. There is also a conserved RING finger-like motif along the sequence of SNAMA following a C2HC zinc finger.
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Affiliation(s)
- Arshad Mather
- School of Molecular and Cell Biology, University of the Witwatersrand. Wits. 2050, South Africa
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263
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Tait SWG, Werner AB, de Vries E, Borst J. Mechanism of action of Drosophila Reaper in mammalian cells: Reaper globally inhibits protein synthesis and induces apoptosis independent of mitochondrial permeability. Cell Death Differ 2005; 11:800-11. [PMID: 15044965 DOI: 10.1038/sj.cdd.4401410] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Drosophila Reaper can bind inhibitor of apoptosis proteins (IAP) and thereby rescue caspases from proteasomal degradation. In insect cells, this is sufficient to induce apoptosis. Reaper can also induce apoptosis in mammalian cells, in which caspases need to be activated, usually via the mitochondrial pathway. Nevertheless, we find that Reaper efficiently induces apoptosis in mammalian cells in the absence of mitochondrial permeabilisation and cytochrome c release. Moreover, this capacity was only marginally affected by deletion of Reaper's amino-terminal IAP-binding motif. Independent of this motif, Reaper could globally suppress protein synthesis. Deletion of 20 amino acids from the carboxy-terminus of Reaper fully abrogated its potential to inhibit protein synthesis and to induce apoptosis in the absence of IAP-binding. Our findings indicate that the newly identified capacity of Reaper to suppress protein translation can operate in mammalian cells and may be key to its pro-apoptotic activity.
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Affiliation(s)
- S W G Tait
- Division of Immunology, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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264
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Berghmans S, Murphey RD, Wienholds E, Neuberg D, Kutok JL, Fletcher CDM, Morris JP, Liu TX, Schulte-Merker S, Kanki JP, Plasterk R, Zon LI, Look AT. tp53 mutant zebrafish develop malignant peripheral nerve sheath tumors. Proc Natl Acad Sci U S A 2005; 102:407-12. [PMID: 15630097 PMCID: PMC544293 DOI: 10.1073/pnas.0406252102] [Citation(s) in RCA: 470] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
TP53 is the most frequently mutated tumor suppressor gene in human cancer, with nearly 50% of all tumors exhibiting a loss-of-function mutation. To further elucidate the genetic pathways involving TP53 and cancer, we have exploited the zebrafish, a powerful vertebrate model system that is amenable to whole-genome forward-genetic analysis and synthetic-lethal screens. Zebrafish lines harboring missense mutations in the tp53 DNA-binding domain were identified by using a target-selected mutagenesis strategy. Homozygous mutant fish from two of these lines were viable and exhibited mutations similar to those found in human cancers (tp53(N168K) and tp53(M214K)). Although homozygous tp53(N168K) mutants were temperature-sensitive and suppressed radiation-induced apoptosis only at 37 degrees C, cells in the tp53(M214K) embryos failed to undergo apoptosis in response to gamma radiation at both 28 and 37 degrees C. Unlike wild-type control embryos, irradiated tp53(M214K) embryos also failed to up-regulate p21 and did not arrest at the G(1)/S checkpoint. Beginning at 8.5 months of age, 28% of tp53(M214K) mutant fish developed malignant peripheral nerve sheath tumors. In addition to providing a model for studying the molecular pathogenic pathways of malignant peripheral nerve sheath tumors, these mutant zebrafish lines provide a unique platform for modifier screens to identify genetic mutations or small molecules that affect tp53-related pathways, including apoptosis, cell-cycle delay, and tumor suppression.
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Affiliation(s)
- Stéphane Berghmans
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Division of Hematology/Oncology, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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265
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Lane DP. Exploiting the p53 pathway for the diagnosis and therapy of human cancer. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2005; 70:489-497. [PMID: 16869788 DOI: 10.1101/sqb.2005.70.049] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
After 26 years of research and the publication of 38,000 papers, our knowledge of the p53 human tumor suppressor protein is impressive. Over half of all human cancers have mutations in the p53 gene, and the p53 pathway in animal models dramatically regulates the cellular response to ionizing radiation and chemotherapeutic drugs. The ability to translate this knowledge to patient benefit is, however, still in its infancy. The many approaches to determining the status of the p53 pathway in human tumor biopsy samples and the attempts to develop p53-selective therapies are described. A great deal of our knowledge of the p53 system remains incomplete, and the issue of how to best conduct translational research in cancer is debated using the difficulties around the p53 system as an example. The need for a more unified and coordinated approach to critical technological developments and clinical trial protocols is discussed.
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Affiliation(s)
- D P Lane
- Institute of Cell and Molecular Biology, Singapore
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266
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Hay BA, Huh JR, Guo M. The genetics of cell death: approaches, insights and opportunities in Drosophila. Nat Rev Genet 2004; 5:911-22. [PMID: 15573123 DOI: 10.1038/nrg1491] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Cell death is ubiquitous in metazoans and involves the action of an evolutionarily conserved process known as programmed cell death or apoptosis. In Drosophila melanogaster, it is now uniquely possible to screen for genes that determine the fate - life or death - of any cell or population of cells during development and in the adult. This review describes these genetic approaches and the key insights into cell-death mechanisms that have been obtained, as well as the outstanding questions that these techniques can help to answer.
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Affiliation(s)
- Bruce A Hay
- Division of Biology, MC156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
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267
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Schumacher B, Schertel C, Wittenburg N, Tuck S, Mitani S, Gartner A, Conradt B, Shaham S. C. elegans ced-13 can promote apoptosis and is induced in response to DNA damage. Cell Death Differ 2004; 12:153-61. [PMID: 15605074 DOI: 10.1038/sj.cdd.4401539] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The p53 tumor suppressor promotes apoptosis in response to DNA damage. Here we describe the Caenorhabditis elegans gene ced-13, which encodes a conserved BH3-only protein. We show that ced-13 mRNA accumulates following DNA damage, and that this accumulation is dependent on an intact C. elegans cep-1/p53 gene. We demonstrate that CED-13 protein physically interacts with the antiapoptotic Bcl-2-related protein CED-9. Furthermore, overexpression of ced-13 in somatic cells leads to the death of cells that normally survive, and this death requires the core apoptotic pathway of C. elegans. Recent studies have implicated two BH3-only proteins, Noxa and PUMA, in p53-induced apoptosis in mammals. Our studies suggest that in addition to the BH3-only protein EGL-1, CED-13 might also promote apoptosis in the C. elegans germ line in response to p53 activation. We propose that an evolutionarily conserved pathway exists in which p53 promotes cell death by inducing expression of two BH3-only genes.
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Affiliation(s)
- B Schumacher
- Max-Planck-Institute of Biochemistry, Am Klopferspitz 18A, 82152 Martinsried, Germany
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268
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Pérez-Garijo A, Martín FA, Morata G. Caspase inhibition during apoptosis causes abnormal signalling and developmental aberrations inDrosophila. Development 2004; 131:5591-8. [PMID: 15496444 DOI: 10.1242/dev.01432] [Citation(s) in RCA: 271] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Programmed cell death or apoptosis plays an important role in the development of multicellular organisms and can also be induced by various stress events. In the Drosophila wing imaginal disc there is little apoptosis in normal development but X-rays can induce high apoptotic levels,which eliminate a large fraction of the disc cells. Nevertheless, irradiated discs form adult patterns of normal size, indicating the existence of compensatory mechanisms. We have characterised the apoptotic response of the wing disc to X-rays and heat shock and also the developmental consequences of compromising apoptosis. We have used the caspase inhibitor P35 to prevent the death of apoptotic cells and found that it causes increased non-autonomous cell proliferation, invasion of compartments and persistent misexpression of the wingless (wg) and decapentaplegic(dpp) signalling genes. We propose that a feature of cells undergoing apoptosis is to activate wg and dpp, probably as part of the mechanism to compensate for cell loss. If apoptotic cells are not eliminated,they continuously emit Wg and Dpp signals, which results in developmental aberrations. We suggest that a similar process of uncoupling apoptosis initiation and cell death may occur during tumour formation in mammalian cells.
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Affiliation(s)
- Ainhoa Pérez-Garijo
- Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid, Madrid 28049, Spain
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269
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Miguel-Aliaga I, Thor S. Segment-specific prevention of pioneer neuron apoptosis by cell-autonomous, postmitotic Hox gene activity. Development 2004; 131:6093-105. [PMID: 15537690 DOI: 10.1242/dev.01521] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In vertebrates, neurons often undergo apoptosis after differentiating and extending their axons. By contrast, in the developing nervous system of invertebrate embryos apoptosis typically occurs soon after cells are generated. Here, we show that the Drosophila dMP2 and MP1 pioneer neurons undergo segment-specific apoptosis at late embryonic stages, long after they have extended their axons and have performed their pioneering role in guiding follower axons. This segmental specificity is achieved by differential expression of the Hox gene Abdominal B, which in posterior segments prevents pioneer neuron death postmitotically and cell-autonomously by repressing the RHG-motif cell death activators reaper and grim. Our results identify the first clear case of a cell-autonomous and anti-apoptotic role for a Hox gene in vivo. In addition, they provide a novel mechanism linking Hox positional information to differences in neuronal architecture along the anteroposterior axis by the selective elimination of mature neurons.
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Affiliation(s)
- Irene Miguel-Aliaga
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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270
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Ciapponi L, Cenci G, Ducau J, Flores C, Johnson-Schlitz D, Gorski MM, Engels WR, Gatti M. The Drosophila Mre11/Rad50 complex is required to prevent both telomeric fusion and chromosome breakage. Curr Biol 2004; 14:1360-6. [PMID: 15296753 DOI: 10.1016/j.cub.2004.07.019] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 06/23/2004] [Accepted: 06/24/2004] [Indexed: 12/12/2022]
Abstract
The MRN complex consists of the two evolutionarily conserved components Mre11 and Rad50 and the third less-conserved component Nbs1/Xrs2. This complex mediates telomere maintenance in addition to a variety of functions in response to DNA double-strand breaks, including homologous recombination, nonhomologous end joining (NHEJ), and activation of DNA damage checkpoints. Mutations in the Mre11 gene cause the human ataxia-telangiectasia-like disorder (ATDL). Here, we show that null mutations in the Drosophila mre11 and rad50 genes cause both telomeric fusion and chromosome breakage. Moreover, we demonstrate that these mutations are in the same epistasis group required for telomere capping and mitotic chromosome integrity. Using an antibody against Rad50, we show that this protein is uniformly distributed along mitotic chromosomes, and that Rad50 is unstable in the absence of its binding partner Mre11. To define the roles of rad50 and mre11 in telomere protection, mutant chromosome preparations were immunostained for both HP1 and HOAP, two proteins that protect Drosophila telomeres from fusion. Cytological analysis revealed that mutations in rad50 and mre11 drastically reduce accumulation of HOAP and HP1 at telomeres. This suggests that the MRN complex protects Drosophila telomeres by facilitating recruitment of HOAP and HP1 at chromosome ends.
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Affiliation(s)
- Laura Ciapponi
- Dipartimento di Genetica e Biologia Molecolare and Istituto di Biologia e Patologia Molecolari del Consiglio Nazionale delle Ricerche, Università di Roma La Sapienza, 00185 Rome, Italy
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271
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Silva E, Tiong S, Pedersen M, Homola E, Royou A, Fasulo B, Siriaco G, Campbell SD. ATM is required for telomere maintenance and chromosome stability during Drosophila development. Curr Biol 2004; 14:1341-7. [PMID: 15296750 DOI: 10.1016/j.cub.2004.06.056] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 05/27/2004] [Accepted: 05/28/2004] [Indexed: 10/26/2022]
Abstract
ATM is a large, multifunctional protein kinase that regulates responses required for surviving DNA damage: including DNA repair, apoptosis, and cell cycle checkpoints. Here, we show that Drosophila ATM function is essential for normal adult development. Extensive, inappropriate apoptosis occurs in proliferating atm mutant tissues, and in clonally derived atm mutant embryos, frequent mitotic defects were seen. At a cellular level, spontaneous telomere fusions and other chromosomal abnormalities are common in atm larval neuroblasts, suggesting a conserved and essential role for dATM in the maintenance of normal telomeres and chromosome stability. Evidence from other systems supports the idea that DNA double-strand break (DSB) repair functions of ATM kinases promote telomere maintenance by inhibition of illegitimate recombination or fusion events between the legitimate ends of chromosomes and spontaneous DSBs. Drosophila will be an excellent model system for investigating how these ATM-dependent chromosome structural maintenance functions are deployed during development. Because neurons appear to be particularly sensitive to loss of ATM in both flies and humans, this system should be particularly useful for identifying cell-specific factors that influence sensitivity to loss of dATM and are relevant for understanding the human disease, ataxia-telangiectasia.
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Affiliation(s)
- Elizabeth Silva
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
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272
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Qi D, Larsson J, Mannervik M. Drosophila Ada2b is required for viability and normal histone H3 acetylation. Mol Cell Biol 2004; 24:8080-9. [PMID: 15340070 PMCID: PMC515027 DOI: 10.1128/mcb.24.18.8080-8089.2004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Regulation of chromatin through histone acetylation is an important step in gene expression. The Gcn5 histone acetyltransferase is part of protein complexes, e.g., the SAGA complex, that interact with transcriptional activators, targeting the enzyme to specific promoters and assisting in recruitment of the basal RNA polymerase transcription machinery. The Ada2 protein directly binds to Gcn5 and stimulates its catalytic activity. Drosophila contains two Ada2 proteins, Drosophila Ada2a (dAda2a) and dAda2b. We have generated flies that lack dAda2b, which is part of a Drosophila SAGA-like complex. dAda2b is required for viability in Drosophila, and its deletion causes a reduction in histone H3 acetylation. A global hypoacetylation of chromatin was detected on polytene chromosomes in dAda2b mutants. This indicates that the dGcn5-dAda2b complex could have functions in addition to assisting in transcriptional activation through gene-specific acetylation. Although the Drosophila p53 protein was previously shown to interact with the SAGA-like complex in vitro, we find that p53 induction of reaper gene expression occurs normally in dAda2b mutants. Moreover, dAda2b mutant animals show excessive p53-dependent apoptosis in response to gamma radiation. Based on this result, we speculate that dAda2b may be necessary for efficient DNA repair or generation of a DNA damage signal. This could be an evolutionarily conserved function, since a yeast ada2 mutant is also sensitive to a genotoxic agent.
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Affiliation(s)
- Dai Qi
- Department of Developmental Biology, Wenner-Gren Institute, Arrheniuslaboratories E3, Stockholm University, S-106 91 Stockholm, Sweden
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273
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Ryoo HD, Gorenc T, Steller H. Apoptotic Cells Can Induce Compensatory Cell Proliferation through the JNK and the Wingless Signaling Pathways. Dev Cell 2004; 7:491-501. [PMID: 15469838 DOI: 10.1016/j.devcel.2004.08.019] [Citation(s) in RCA: 478] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 08/31/2004] [Accepted: 08/31/2004] [Indexed: 10/26/2022]
Abstract
In many metazoans, damaged and potentially dangerous cells are rapidly eliminated by apoptosis. In Drosophila, this is often compensated for by extraproliferation of neighboring cells, which allows the organism to tolerate considerable cell death without compromising development and body size. Despite its importance, the mechanistic basis of such compensatory proliferation remains poorly understood. Here, we show that apoptotic cells express the secretory factors wingless (wg) and decapentaplegic (dpp). When cells undergoing apoptosis were kept alive with the caspase inhibitor p35, excessive nonautonomous cell proliferation was observed. Significantly, wg signaling is necessary and, at least in some cells, also sufficient for mitogenesis under these conditions. Finally, we provide evidence that the DIAP1 antagonists reaper and hid can activate the JNK pathway and that this pathway is required for inducing wg and cell proliferation. These findings support a model where apoptotic cells activate signaling cascades for compensatory proliferation.
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Affiliation(s)
- Hyung Don Ryoo
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, Box 252, New York, NY 10021, USA
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274
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Lin HV, Rogulja A, Cadigan KM. Wingless eliminates ommatidia from the edge of the developing eye through activation of apoptosis. Development 2004; 131:2409-18. [PMID: 15128670 DOI: 10.1242/dev.01104] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila compound eye is formed by selective recruitment of undifferentiated cells into clusters called ommatidia during late larval and early pupal development. Ommatidia at the edge of the eye, which often lack the full complement of photoreceptors and support cells, undergo apoptosis during mid-pupation. We have found that this cell death is triggered by the secreted glycoprotein Wingless, which activates its own expression in peripheral ommatidia via a positive feedback loop. Wingless signaling elevates the expression of the pro-apoptotic factors head involution defective, grim and reaper, which are required for ommatidial elimination. We estimate that approximately 6-8% of the total photoreceptor pool in each eye is removed by this mechanism. In addition, we show that the retinal apoptosis previously reported in apc1 mutants occurs at the same time as the peripheral ommatidial cell death and also depends on head involution defective, grim and reaper. We consider the implications of these findings for eye development and function in Drosophila and other organisms.
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Affiliation(s)
- Hua V Lin
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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275
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Richardson C, Horikoshi N, Pandita TK. The role of the DNA double-strand break response network in meiosis. DNA Repair (Amst) 2004; 3:1149-64. [PMID: 15279804 DOI: 10.1016/j.dnarep.2004.05.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Organisms with sexual reproduction have two homologous copies of each chromosome. Meiosis is characterized by two successive cell divisions that result in four haploid sperms or eggs, each carrying a single copy of homologous chromosome. This process requires a coordinated reorganization of chromatin and a complex network of meiotic-specific signaling cascades. At the beginning of meiosis, each chromosome must recognize its homolog, then the two become intimately aligned along their entire lengths which allows the exchange of DNA strands between homologous sequences to generate genetic diversity. DNA double-strand breaks (DSBs) initiate meiotic recombination in a variety of organisms. Numerous studies have identified both the genomic loci of the initiating DSBs and the proteins involved in their formation. This review will summarize the activation and signaling networks required for the DSB response in meiosis.
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Affiliation(s)
- Christine Richardson
- College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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276
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Oikemus SR, McGinnis N, Queiroz-Machado J, Tukachinsky H, Takada S, Sunkel CE, Brodsky MH. Drosophila atm/telomere fusion is required for telomeric localization of HP1 and telomere position effect. Genes Dev 2004; 18:1850-61. [PMID: 15256487 PMCID: PMC517405 DOI: 10.1101/gad.1202504] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Terminal deletions of Drosophila chromosomes can be stably protected from end-to-end fusion despite the absence of all telomere-associated sequences. The sequence-independent protection of these telomeres suggests that recognition of chromosome ends might contribute to the epigenetic protection of telomeres. In mammals, Ataxia Telangiectasia Mutated (ATM) is activated by DNA damage and acts through an unknown, telomerase-independent mechanism to regulate telomere length and protection. We demonstrate that the Drosophila homolog of ATM is encoded by the telomere fusion (tefu) gene. In the absence of ATM, telomere fusions occur even though telomere-specific Het-A sequences are still present. High levels of spontaneous apoptosis are observed in ATM-deficient tissues, indicating that telomere dysfunction induces apoptosis in Drosophila. Suppression of this apoptosis by p53 mutations suggests that loss of ATM activates apoptosis through a DNA damage-response mechanism. Loss of ATM reduces the levels of heterochromatin protein 1 (HP1) at telomeres and suppresses telomere position effect. We propose that recognition of chromosome ends by ATM prevents telomere fusion and apoptosis by recruiting chromatin-modifying complexes to telomeres.
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Affiliation(s)
- Sarah R Oikemus
- Program in Gene Function and Expression and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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277
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Sutcliffe JE, Brehm A. Of flies and men; p53, a tumour suppressor. FEBS Lett 2004; 567:86-91. [PMID: 15165898 DOI: 10.1016/j.febslet.2004.03.122] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Accepted: 03/14/2004] [Indexed: 12/25/2022]
Abstract
The completion of the Drosophila genome sequencing project [Science 287 (2000) 2185] has reconfirmed the fruit fly as a model organism to study human disease. Comparison studies have shown that two thirds of genes implicated in human cancers have counterparts in the fly [Curr. Opin. Genet. Dev. 11 (2001) 274; J. Cell Biol. 150 (2000) F23], including the tumour suppressor, p53. The suitability of the fruit fly to study the function of the tumour suppressor p53 is further exemplified by the lack of p53 family members within the fly genome, i.e., no homologues to p63 and p73 have been identified. Hence, there is no redundancy between family members greatly facilitating the analysis of p53 function. In addition, studying p53 in Drosophila provides an opportunity to learn about the evolution of tumour suppressors. Here, we will discuss what is known about Drosophila p53 in relation to human p53.
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Affiliation(s)
- Josephine E Sutcliffe
- Lehrstuhl für Molekularbiologie, Adolf-Butenandt-Institut, Ludwig-Maximilians-Universität, Schillerstrasse 44, 80336 Munich, Germany
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278
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Morey M, Corominas M, Serras F. DIAP1 suppresses ROS-induced apoptosis caused by impairment of the selD/sps1 homolog in Drosophila. J Cell Sci 2004; 116:4597-604. [PMID: 14576353 DOI: 10.1242/jcs.00783] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cellular antioxidant defense systems neutralize the cytotoxic by-products referred to as reactive oxygen species (ROS). Among them, selenoproteins have important antioxidant and detoxification functions. The interference in selenoprotein biosynthesis results in accumulation of ROS and consequently in a toxic intracellular environment. The resulting ROS imbalance can trigger apoptosis to eliminate the deleterious cells. In Drosophila, a null mutation in the selD gene (homologous to the human selenophosphate synthetase type 1) causes an impairment of selenoprotein biosynthesis, a ROS burst and lethality. We propose this mutation (known as selDptuf) as a tool to understand the link between ROS accumulation and cell death. To this aim we have analyzed the mechanism by which selDptuf mutant cells become apoptotic in Drosophila imaginal discs. The apoptotic effect of selDptuf does not require the activity of the Ras/MAPK-dependent proapoptotic gene hid, but results in stabilization of the tumor suppressor protein Dmp53 and transcription of the Drosophila pro-apoptotic gene reaper (rpr). We also provide genetic evidence that the initiator caspase DRONC is activated and that the effector caspase DRICE is processed to commit selDptuf mutant cells to death. Moreover, the ectopic expression of the inhibitor of apoptosis DIAP1 rescues the cellular viability of selDptuf mutant cells. These observations indicate that selDptuf ROS-induced apoptosis in Drosophila is mainly driven by the caspase-dependent Dmp53/Rpr pathway.
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Affiliation(s)
- Marta Morey
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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279
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Abstract
p53 is frequently mutated in cancer and as a result is one of the most intensely studied tumour suppressors. Analysis of the primitive forms of p53 found in Caenorhabditis elegans and Drosophila, alongside studies using transgenic mouse models, indicate that the induction of apoptosis is both the most conserved function of p53 and vital for tumour suppression. p53-mediated apoptosis occurs through a combination of mechanisms which include pathways that are both dependent and independent of alterations in gene expression. In response to genotoxic insult, these pathways probably act together, thereby amplifying the apoptotic signal. However, the picture is complicated because the p53 activity is determined by stress type and individual cellular characteristics. The numerous p53 responsive genes that have been identified also provide further means of controlling the actions of p53. The recent discoveries of proteins that interact with p53 and specifically regulate the ability of p53 to trigger apoptosis have provided further mechanistic insights into the role of p53 in inducing cell death. Understanding the molecular basis of the proapoptotic action of p53 can assist in our quest to reintroduce or reactivate p53 in human tumours.
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Affiliation(s)
- Elizabeth A Slee
- Imperial College School of Medicine at St Mary's, Ludwig Institute for Cancer Research, Norfolk Place, London W2 1PG, UK
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280
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Yamaguchi M, Hirose F, Inoue YH, Ohno K, Yoshida H, Hayashi Y, Deak P, Matsukage A. Genetic link between p53 and genes required for formation of the zonula adherens junction. Cancer Sci 2004; 95:436-41. [PMID: 15132772 PMCID: PMC11158819 DOI: 10.1111/j.1349-7006.2004.tb03228.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Revised: 03/10/2004] [Accepted: 03/10/2004] [Indexed: 11/27/2022] Open
Abstract
Ectopic expression of human p53 in Drosophila eye imaginal disc cells induces apoptosis and results in a rough eye phenotype in the adult flies. We have screened Drosophila stocks to identify mutations that enhance or suppress the p53-induced rough eye phenotype. One of the dominant enhancers of the p53-induced rough eye phenotype corresponds to a loss-of-function mutation of the crumbs gene, which is essential for the biogenesis of the zonula adherens junction and the establishment of apical polarity in epithelial cells. Enhancement of p53-induced apoptosis in the eye imaginal discs by a half-reduction of the crumbs gene dose was confirmed by a TUNEL method. Furthermore, mutations of genes for Shotgun (Drosophila E-cadherin) and Armadillo (Drosophila beta-catenin), the two main components of the adherens junction, also strongly enhanced the p53-induced rough eye phenotype. These results suggest that human p53 senses subtle abnormality at the adherens junction or in signals derived from the junction, and consequently induces apoptosis to remove abnormal cells from tissue. Thus p53 likely plays a role as a guardian of the tissue not only by sensing the damaged DNA, but also by sensing signals from the adherens junction.
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Affiliation(s)
- Masamitsu Yamaguchi
- Department of Applied Biology, Faculty of Textile Science, Drosophila Genetic Resource Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
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281
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Zaka R, Chenal C, Misset MT. Effects of low doses of short-term gamma irradiation on growth and development through two generations of Pisum sativum. THE SCIENCE OF THE TOTAL ENVIRONMENT 2004; 320:121-9. [PMID: 15016502 DOI: 10.1016/j.scitotenv.2003.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2002] [Accepted: 08/13/2003] [Indexed: 05/06/2023]
Abstract
The effects of short-term gamma radiation on pea plants were investigated by exposing 5-day-old seedlings with doses ranging from 0 to 60 Gy, and studying plant growth and development over two generations after irradiation. Doses higher than 6 Gy significantly inhibited the G1 plant growth and productivity, and no seedling survived irradiation with 40 Gy and above. These effects were transmitted and were even more severe in the next generation, G2. Irradiated G1 (> or =10 Gy) and G2 (> or = 0.4 Gy) plants were significantly smaller than controls. The mean number of pods produced per plant was reduced by at least 20% at all doses in both G1 and G2. In parallel, the mean numbers of ovules and normally developed seeds per pod were significantly reduced after 10 Gy in G1 and after 0.4 Gy in G2, leading to a significant drop in seed production. This effect was correlated with a linear decrease in male fertility linked to abnormal meiosis (tetrads with micronuclei) as a function of doses from 0 to 10 Gy, in G1 and G2 plants. These long-term changes in plant development demonstrate a genomic instability induced by irradiation. However, there were neither quantitative nor qualitative changes in storage proteins in G1 seeds at any of the irradiation doses tested from 0 to 10 Gy.
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Affiliation(s)
- R Zaka
- UMR-CNRS 6553 Ecobio, Equipe Evolution des Populations et des Espèces, Université de Rennes 1, Campus de Beaulieu Bât. 14, Rennes Cedex F 35042, France
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282
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Abstract
The recent discovery of two genes, termed p63 and p73, encoding transcription factors highly homologous to p53 presents unexpected challenges and opportunities for the understanding and treatment of cancers. The questions raised are many but center on determining whether these new genes possess novel tumor suppressor functions, cooperate with p53, or impart oncogenic effects. At present there is considerable discord in the field concerning these concepts with some favoring a tumor suppressor role for the p53 family members and others an oncogenic influence. In support of a tumor suppressor role is the ability of p73 and p63 isoforms to transactivate p53 target genes and the large body of work linking p73, and to some extent p63, in apoptotic events in response to cellular stresses generally considered the purview of p53. More recently, p73 has been implicated in cell death following T cell activation, the response of cancers to chemotherapy, and finally, along with p63, to the function of p53 itself. Opposing this view is the fact that the p73 and p63 genes are rarely mutated in cancers and the stark absence of tumors in the p73 null mouse. Moreover, the high expression of dominant negative (dn) versions of the p73 and p63 proteins supports an anti-p53 function and therefore possibly an oncogenic effect. Indeed, the p63 gene is located in a region of chromosome three amplified in squamous cell carcinomas and the number of reports of dn-p63 overexpression in these diseases is increasing. This review will examine both sides of these arguments in an attempt to decipher common themes and to identify opportunities these genes represent for understanding tumorigenesis.
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Affiliation(s)
- Frank D McKeon
- Department of Cell Biology, Harvard Medical School, USA.
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283
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Jaklevic BR, Su TT. Relative contribution of DNA repair, cell cycle checkpoints, and cell death to survival after DNA damage in Drosophila larvae. Curr Biol 2004; 14:23-32. [PMID: 14711410 DOI: 10.1016/j.cub.2003.12.032] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Components of the DNA damage checkpoint are essential for surviving exposure to DNA damaging agents. Checkpoint activation leads to cell cycle arrest, DNA repair, and apoptosis in eukaryotes. Cell cycle regulation and DNA repair appear essential for unicellular systems to survive DNA damage. The relative importance of these responses and apoptosis for surviving DNA damage in multicellular organisms remains unclear. RESULTS After exposure to ionizing radiation, wild-type Drosophila larvae regulate the cell cycle and repair DNA; grp (DmChk1) mutants cannot regulate the cell cycle but repair DNA; okra (DmRAD54) mutants regulate the cell cycle but are deficient in repair of double strand breaks (DSB); mei-41 (DmATR) mutants cannot regulate the cell cycle and are deficient in DSB repair. All undergo radiation-induced apoptosis. p53 mutants regulate the cell cycle but fail to undergo apoptosis. Of these, mutants deficient in DNA repair, mei-41 and okra, show progressive degeneration of imaginal discs and die as pupae, while other genotypes survive to adulthood after irradiation. Survival is accompanied by compensatory growth of imaginal discs via increased nutritional uptake and cell proliferation, presumably to replace dead cells. CONCLUSIONS DNA repair is essential for surviving radiation as expected; surprisingly, cell cycle regulation and p53-dependent cell death are not. We propose that processes resembling regeneration of discs act to maintain tissues and ultimately determine survival after irradiation, thus distinguishing requirements between muticellular and unicellular eukaryotes.
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284
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Brodsky MH, Weinert BT, Tsang G, Rong YS, McGinnis NM, Golic KG, Rio DC, Rubin GM. Drosophila melanogaster MNK/Chk2 and p53 regulate multiple DNA repair and apoptotic pathways following DNA damage. Mol Cell Biol 2004; 24:1219-31. [PMID: 14729967 PMCID: PMC321428 DOI: 10.1128/mcb.24.3.1219-1231.2004] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We have used genetic and microarray analysis to determine how ionizing radiation (IR) induces p53-dependent transcription and apoptosis in Drosophila melanogaster. IR induces MNK/Chk2-dependent phosphorylation of p53 without changing p53 protein levels, indicating that p53 activity can be regulated without an Mdm2-like activity. In a genome-wide analysis of IR-induced transcription in wild-type and mutant embryos, all IR-induced increases in transcript levels required both p53 and the Drosophila Chk2 homolog MNK. Proapoptotic targets of p53 include hid, reaper, sickle, and the tumor necrosis factor family member EIGER: Overexpression of Eiger is sufficient to induce apoptosis, but mutations in Eiger do not block IR-induced apoptosis. Animals heterozygous for deletions that span the reaper, sickle, and hid genes exhibited reduced IR-dependent apoptosis, indicating that this gene complex is haploinsufficient for induction of apoptosis. Among the genes in this region, hid plays a central, dosage-sensitive role in IR-induced apoptosis. p53 and MNK/Chk2 also regulate DNA repair genes, including two components of the nonhomologous end-joining repair pathway, Ku70 and Ku80. Our results indicate that MNK/Chk2-dependent modification of Drosophila p53 activates a global transcriptional response to DNA damage that induces error-prone DNA repair as well as intrinsic and extrinsic apoptosis pathways.
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Affiliation(s)
- Michael H Brodsky
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
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285
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Abstract
The p53 tumor suppressor acts to integrate multiple stress signals into a series of diverse antiproliferative responses. One of the most important p53 functions is its ability to activate apoptosis, and disruption of this process can promote tumor progression and chemoresistance. p53 apparently promotes apoptosis through transcription-dependent and -independent mechanisms that act in concert to ensure that the cell death program proceeds efficiently. Moreover, the apoptotic activity of p53 is tightly controlled, and is influenced by a series of quantitative and qualitative events that influence the outcome of p53 activation. Interestingly, other p53 family members can also promote apoptosis, either in parallel or in concert with p53. Although incomplete, our current understanding of p53 illustrates how apoptosis can be integrated into a larger tumor suppressor network controlled by different signals, environmental factors, and cell type. Understanding this network in more detail will provide insights into cancer and other diseases, and will identify strategies to improve their therapeutic treatment.
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286
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Jassim OW, Fink JL, Cagan RL. Dmp53 protects the Drosophila retina during a developmentally regulated DNA damage response. EMBO J 2004; 22:5622-32. [PMID: 14532134 PMCID: PMC213797 DOI: 10.1093/emboj/cdg543] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Ultraviolet (UV) light is absorbed by cellular proteins and DNA, promoting skin damage, aging and cancer. In this paper, we explore the UV response by cells of the Drosophila retina. We demonstrate that the retina enters a period of heightened UV sensitivity in the young developing pupa, a stage closely associated with its period of normal developmental programmed cell death. Injury to irradiated cells included morphology changes and apoptotic cell death; these defects could be completely accounted for by DNA damage. Cell death, but not morphological changes, was blocked by the caspase inhibitor P35. Utilizing genetic and microarray data, we provide evidence for the central role of Hid expression and for Diap1 protein stability in controlling the UV response. In contrast, we found that Reaper had no effect on UV sensitivity. Surprisingly, Dmp53 is required to protect cells from UV-mediated cell death, an effect attributed to its role in DNA repair. These in vivo results demonstrate that the cellular effects of DNA damage depend on the developmental status of the tissue.
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Affiliation(s)
- Omar W Jassim
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8103, Saint Louis, MO 63110, USA
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287
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Claveria C, Martinez-A C, Torres M. A Bax/Bak-independent Mitochondrial Death Pathway Triggered by Drosophila Grim GH3 Domain in Mammalian Cells. J Biol Chem 2004; 279:1368-75. [PMID: 14551193 DOI: 10.1074/jbc.m309819200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Grim encodes a protein required for programmed cell death in Drosophila, whose proapoptotic activity is conserved in mammalian cells. Two proapoptotic domains are relevant for Grim killing function; the N-terminal region, which induces apoptosis by disrupting inhibitor of apoptosis protein (IAP) blockage of caspase activity, and the internal GH3 domain, which triggers a mitochondrial pathway. We explored the role of these two domains in heterologous killing of mammalian cells by Grim. The GH3 domain is essential for Grim proapoptotic activity in mouse cells, whereas the N-terminal domain is dispensable. The GH3 domain is required and sufficient for Grim targeting to mitochondria and for cytochrome c release in a caspase- and N-terminal-independent, IAP-insensitive manner. These Grim GH3 activities do not require Bax or Bak function, revealing GH3 activity as the first proapoptotic stimulus able to trigger the mitochondrial death pathway in mammalian cells in the absence of multidomain proapoptotic Bcl-2 proteins.
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Affiliation(s)
- Cristina Claveria
- Departamento de Inmunologiía y Oncología, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Cientiíficas, Universidad Autónoma de Madrid Campus de Cantoblanco, E-28049 Madrid, Spain
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288
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Chandrasekaran V, Beckendorf SK. senseless is necessary for the survival of embryonic salivary glands in Drosophila. Development 2003; 130:4719-28. [PMID: 12925597 DOI: 10.1242/dev.00677] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Apoptosis in developing Drosophila embryos is rare and confined to specific groups of cells. We explain how one organ, salivary glands, of Drosophila embryos avoids apoptosis. senseless (sens), a Zn-finger transcription factor, is expressed in the salivary primordium and later in the differentiated salivary glands. The regulation of sens expression in the salivary placodes is more complex than observed in the embryonic PNS. We have shown that sens expression is initiated in the salivary placodes by fork head (fkh), a winged helix transcription factor. The expression of sens is maintained in the salivary glands by fkh and by daughterless (da), a bHLH family member. In this study, we have identified sage, a salivary-specific bHLH protein as a new heterodimeric partner for da protein in the salivary glands. In addition, our data suggest that sage RNAi embryos have a phenotype similar to sens and that sage is necessary to maintain expression of sens in the embryonic salivary glands. Furthermore, we show that in the salivary glands, sens acts as an anti-apoptotic protein by repressing reaper and possibly hid.
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Affiliation(s)
- Vidya Chandrasekaran
- Department of Molecular and Cell Biology, 401 Barker Hall, University of California, Berkeley, CA 94720, USA
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289
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Delanoue R, Legent K, Godefroy N, Flagiello D, Dutriaux A, Vaudin P, Becker JL, Silber J. The Drosophila wing differentiation factor Vestigial–Scalloped is required for cell proliferation and cell survival at the dorso-ventral boundary of the wing imaginal disc. Cell Death Differ 2003; 11:110-22. [PMID: 14526388 DOI: 10.1038/sj.cdd.4401321] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Links between genes involved in development, proliferation and apoptosis have been difficult to establish. In the Drosophila wing disc, the vestigial (vg) and the scalloped (sd) gene products dimerize to form a functional transcription factor. Ectopic expression of vg in other imaginal discs induces outgrowth and wing tissue specification. We investigated the role of the VG-SD dimer in proliferation and showed that vg antagonizes the effect of dacapo, the cyclin-cdk inhibitor. Moreover, ectopic vg drives cell cycle progression and in HeLa cultured cells, the VG-SD dimer induces cell proliferation per se. In Drosophila, ectopic vg induces expression of dE2F1 and its targets dRNR2 and string. In addition vg, but not dE2F1, interacts with and induces expression of dihydrofolate reductase (DHFR). Moreover, a decrease in VG or addition of aminopterin, a specific DHFR inhibitor, shift the dorso-ventral boundary cells of the disc to a cell death sensitive state that is correlated with reaper induction and DIAP1 downregulation. This indicates that vg in interaction with dE2F1 and DHFR is a critical player for both cell proliferation and cell survival in the presumptive wing margin area.
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Affiliation(s)
- R Delanoue
- Institut Jacques Monod, Tour 43, 2, Place Jussieu, 75251 Paris, France
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290
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Thompson LM, Marsh JL. Invertebrate models of neurologic disease: insights into pathogenesis and therapy. Curr Neurol Neurosci Rep 2003; 3:442-8. [PMID: 12914688 DOI: 10.1007/s11910-003-0028-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The search for cures of human diseases can be very slow, expensive, and serendipitous. Roughly five decades of basic research in a handful of model systems has revealed that most animals are quite similar to one another especially at the cellular and molecular levels. The commonalities allow one to use animal models to investigate human disease mechanisms. Here, we review contributions demonstrating the use of invertebrate models to investigate human neurodegenerative diseases. We conclude that the integration of fly and worm models into programs seeking to identify therapeutic strategies for neurodegenerative disease can significantly speed progress toward finding cures for these devastating diseases.
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Affiliation(s)
- Leslie Michels Thompson
- Department of Psychiatry and Human Behavior, University of California, Irvine, Gillespie 2121, Irvine, CA 92697-4260, USA.
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291
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Lee JH, Lee E, Park J, Kim E, Kim J, Chung J. In vivo p53 function is indispensable for DNA damage-induced apoptotic signaling in Drosophila. FEBS Lett 2003; 550:5-10. [PMID: 12935877 DOI: 10.1016/s0014-5793(03)00771-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
p53 is a representative tumor suppressor whose dysfunction is a major cause of human cancer syndrome. Here we isolated flies lacking Dmp53, which encodes the single Drosophila orthologue of mammalian p53 family. Dmp53 null mutants well developed into adults, only displaying mild defects in longevity and fertility. However, genomic stability and viability of Dmp53 mutants dramatically decreased upon ionizing irradiation. Moreover, mutating Dmp53 abolished irradiation-induced apoptosis and reaper induction. These results indicate that Dmp53 is a central component of DNA damage-dependent apoptotic signaling.
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Affiliation(s)
- Jun Hee Lee
- National Creative Research Initiatives Center for Cell Growth Regulation, Korea Advanced Institute of Science and Technology, Taejon 305-701, South Korea
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292
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Le Bras M, Bensaad K, Soussi T. Data mining the p53 pathway in the Fugu genome: evidence for strong conservation of the apoptotic pathway. Oncogene 2003; 22:5082-90. [PMID: 12902991 DOI: 10.1038/sj.onc.1206424] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The p53 tumour suppressor gene belongs to a small family of related proteins that includes two other members, p63 and p73. Phylogenetic and functional studies suggest that p63 and p73 are ancient genes that have essential roles in normal development, whereas p53 seems to have evolved more recently to prevent cell transformation. In mammalian cells, a plethora of proteins have been found to specifically regulate p53 activity. The genome of the fish Fugu rubripes has been recently published. It is the second vertebrate genome for which the entire sequence is now available. Phylogenetic studies are essential in order to analyse and define signalling pathways important for cell cycle regulation. The presence or absence of a critical member in any pathway can shed light about the evolution of these pathways. The Fugu genome databank has been analysed for several members of the p53 network, including p53, p63 and p73. A good conservation of the network that regulates p53 stability and apoptosis has been found. We also discovered that some cofactors that cooperate with p53 for apoptosis are also well conserved and belong to multigene families not detected in the human genome.
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Affiliation(s)
- Morgane Le Bras
- Laboratoire de Génotoxicologie des Tumeurs, Institut Curie, 26 rue d'Ulm, 75005 Paris, France
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293
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Edwards SJ, Hananeia L, Eccles MR, Zhang YF, Braithwaite AW. The proline-rich region of mouse p53 influences transactivation and apoptosis but is largely dispensable for these functions. Oncogene 2003; 22:4517-23. [PMID: 12881708 DOI: 10.1038/sj.onc.1206726] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The N-terminal proline-rich domain of human p53 has been shown to be important for the induction of apoptosis. However, the corresponding region in mouse and other species is not highly conserved and has been less well studied. In this paper, we have characterized mutants with deletions in this region of mouse p53. Our results demonstrate that deletions in the proline-rich domain have varying effects on function ranging from no effect to severe impairment of cell death activity, depending on precisely which residues are deleted. We also show that the mutants differ in their ability to transactivate different p53 target promoters. Although we have been able to obtain mutants selectively impaired for apoptosis, our data are not generally consistent with this region being a functional domain. The data are more consistent with the interpretation that the region influences function by altering local protein structure which may affect promoter discrimination.
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Affiliation(s)
- Sara J Edwards
- Department of Pathology, Dunedin School of Medicine, University of Otago, Box 913, Dunedin, New Zealand.
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294
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Abstract
For a century, the little fruitfly Drosophila melanogaster has taught generations of geneticists about how genes control the development of a multicellular organism. More recently, Drosophila has begun to contribute more directly towards our understanding of human disease [Bernards A, Hariharan IK. Of flies and men-studying human disease in Drosophila. Curr Opin Genet Dev 2001, 11, 274-278]. It is capable of doing this because it shares many disease-related genes with us. For example, the Drosophila genome sequencing project has revealed that two thirds of the genes implicated in human cancers have a counterpart in the fly genome [Adams MD, Celniker SE, Holt RA, et al. The genome sequence of Drosophila melanogaster. Science 2000, 287, 2185-2195, Fortini ME, Skupski MP, Boguski MS, Hariharan IK. A survey of human disease gene counterparts in the Drosophila genome. J Cell Biol 2000, 150, F23-30]. In particular, the fly has homologues of the Retinoblastoma protein (pRb) and of p53, two prototypical tumour suppressors which are inactivated in the majority of human tumours. Here, we will compare the fly's tumour suppressors with their human counterparts and we will review recent advances in our understanding of how these factors function in the fly.
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Affiliation(s)
- J E Sutcliffe
- Lehrstuhl für Molekularbiologie, Adolf-Butenandt-Institut, Ludwig-Maximilians-Universität, Schillerstr.44, 80336 Munich, Germany
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295
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Gullaud M, Delanoue R, Silber J. A Drosophila model to study the functions of TWIST orthologs in apoptosis and proliferation. Cell Death Differ 2003; 10:641-51. [PMID: 12761573 DOI: 10.1038/sj.cdd.4401222] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The twist gene has been characterized for its role in myogenesis in several species. In addition, in mammalian cultured cells, it has been shown that twist is a potential oncogene antagonizing p53-dependent apoptosis. To study, in vivo, the role of twist in apoptosis and proliferation, we constructed transgenic Drosophila lines allowing ectopic expression of different twist orthologs. We report that: (i) Drosophila twist induces apoptosis and activates the reaper promoter, (ii) nematode twist induces arrest of proliferation without apoptosis, and (iii) human twist retains its potentialities observed in mammalian cultured cells and antagonizes Drosophila p53-dependent apoptosis. In addition, we show that human twist is able to induce cell proliferation in Drosophila. Data suggest that the pathway by which human twist antagonizes Drosophila p53 could be conserved. These transgenic lines thus constitute a powerful tool to identify targets and modifiers of human twist.
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Affiliation(s)
- M Gullaud
- Institut Jacques Monod, Tour43, 2, Place Jussieu, 75005 Paris, France
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296
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Clavería C, Torres M. Mitochondrial apoptotic pathways induced by Drosophila programmed cell death regulators. Biochem Biophys Res Commun 2003; 304:531-7. [PMID: 12729588 DOI: 10.1016/s0006-291x(03)00626-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Multicellular organisms eliminate unwanted or damaged cells by cell death, a process essential to the maintenance of tissue homeostasis. Cell death is a tightly regulated event, whose alteration by excess or defect is involved in the pathogenesis of many diseases such as cancer, autoimmune syndromes, and neurodegenerative processes. Studies in model organisms, especially in the nematode Caenorhabditis elegans, have been crucial in identifying the key molecules implicated in the regulation and execution of programmed cell death. In contrast, the study of cell death in Drosophila melanogaster, often an excellent model organism, has identified regulators and mechanisms not obviously conserved in other metazoans. Recent molecular and cellular analyses suggest, however, that the mechanisms of action of the main programmed cell death regulators in Drosophila include a canonical mitochondrial pathway.
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Affiliation(s)
- Cristina Clavería
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, UAM Campus de Cantoblanco, E-28049 Madrid, Spain
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297
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Kusch T, Guelman S, Abmayr SM, Workman JL. Two Drosophila Ada2 homologues function in different multiprotein complexes. Mol Cell Biol 2003; 23:3305-19. [PMID: 12697829 PMCID: PMC153191 DOI: 10.1128/mcb.23.9.3305-3319.2003] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The reversible acetylation of the N-terminal tails of histones is crucial for transcription, DNA repair, and replication. The enzymatic reaction is catalyzed by large multiprotein complexes, of which the best characterized are the Gcn5-containing N-acetyltransferase (GNAT) complexes. GNAT complexes from yeast to humans share several conserved subunits, such as Ada2, Ada3, Spt3, and Tra1/TRRAP. We have characterized these factors in Drosophila and found that the flies have two distinct Ada2 variants (dAda2a and dAda2b). Using a combination of biochemical and cell biological approaches we demonstrate that only one of the two Drosophila Ada2 homologues, dAda2b, is a component of Spt-Ada-Gcn5-acetyltransferase (SAGA) complexes. The other Ada2 variant, dAda2a, can associate with dGcn5 but is not incorporated into dSAGA-type complexes. This is the first example of a complex-specific association of the Ada-type transcriptional adapter proteins with GNATs. In addition, dAda2a is part of Gcn5-independent complexes, which are concentrated at transcriptionally active regions on polytene chromosomes. This implicates novel functions for dAda2a in transcription. Humans and mice also possess two Ada2 variants with high homology to dAda2a and dAda2b, respectively. This suggests that the mammalian and fly homologues of the transcriptional adapter Ada2 form two functionally distinct subgroups with unique characteristics.
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Affiliation(s)
- Thomas Kusch
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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298
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Abstract
Organisms with renewable tissues use a network of genetic pathways and cellular responses to prevent cancer. The main mammalian tumour-suppressor pathways evolved from ancient mechanisms that, in simple post-mitotic organisms, act predominantly to regulate embryogenesis or to protect the germline. The shift from developmental and/or germline maintenance in simple organisms to somatic maintenance in complex organisms might have evolved at a cost. Recent evidence indicates that some mammalian tumour-suppressor mechanisms contribute to ageing. How might this have happened, and what are its implications for our ability to control cancer and ageing?
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Affiliation(s)
- Judith Campisi
- Lawrence Berkeley National Laboratory, Life Sciences Division, 1 Cyclotron Road, Berkeley, California 94720, USA.
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299
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Abstract
Programmed cell death or apoptosis is crucial to normal development and tissue homeostasis in multicellular organisms. In many cases malfunctioning of apoptotic pathways has disastrous consequences for the organism, like in the case of cancer, AIDS or neurodegenerative diseases, which all are associated with the inappropriate regulation of programmed cell death. In Drosophila, patterns of programmed cell death have been studied, and it is known that the induction of apoptosis requires the products of three closely linked genes, reaper (rpr), head involution defective (hid) and grim. Although it has been shown that rpr, hid and grim induce apoptosis through similar mechanisms, it is clear that they are not functionally equivalent, since their transcripts are differentially expressed in response to different signals. In this study, I dissected the temporal and spatial expression of the apoptosis promoting gene rpr by generating a series of reporter lines, which recapitulate various aspects of the endogenous rpr expression. Understanding the regulatory logic of reaper transcription will help to advance our knowledge of apoptosis regulation in Drosophila and in other organisms.
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Affiliation(s)
- Ingrid Lohmann
- Max Planck Institute for Developmental Biology, Department of Molecular Biology, Spemannstrasse 37-39, D-72076 Tübingen, Germany.
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300
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Sogame N, Kim M, Abrams JM. Drosophila p53 preserves genomic stability by regulating cell death. Proc Natl Acad Sci U S A 2003; 100:4696-701. [PMID: 12672954 PMCID: PMC153618 DOI: 10.1073/pnas.0736384100] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
When animal cells are exposed to stressful conditions, the tumor suppressor protein p53 restrains growth by promoting an arrested cell cycle or initiating a cell death program. How these distinct fates are specified through the action of a single protein is not known. To study its functions in vivo we produced a targeted mutation at the Drosophila p53 (Dmp53) locus. We show that Dmp53 is required for damage-induced apoptosis but not for cell-cycle arrest. Dmp53 function is also required for damage-induced transcription of two tightly linked cell death activators, reaper and sickle. When challenged by ionizing radiation, Dmp53 mutants exhibit radiosensitivity and genomic instability. Hence, elevated mutant loads were not caused by defective checkpoint functions but instead correlated with failures in p53-associated cell death. Our studies support the notion that core ancestral functions of the p53 gene family are intimately coupled to cell death as an adaptive response to maintain genomic stability.
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Affiliation(s)
- Naoko Sogame
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9039, USA
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