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Coordination between cell proliferation and apoptosis after DNA damage in Drosophila. Cell Death Differ 2022; 29:832-845. [PMID: 34824391 PMCID: PMC8989919 DOI: 10.1038/s41418-021-00898-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 12/31/2022] Open
Abstract
Exposure to genotoxic stress promotes cell cycle arrest and DNA repair or apoptosis. These "life" or "death" cell fate decisions often rely on the activity of the tumor suppressor gene p53. Therefore, the precise regulation of p53 is essential to maintain tissue homeostasis and to prevent cancer development. However, how cell cycle progression has an impact on p53 cell fate decision-making is mostly unknown. In this work, we demonstrate that Drosophila p53 proapoptotic activity can be impacted by the G2/M kinase Cdk1. We find that cell cycle arrested or endocycle-induced cells are refractory to ionizing radiation-induced apoptosis. We show that p53 binding to the regulatory elements of the proapoptotic genes and its ability to activate their expression is compromised in experimentally arrested cells. Our results indicate that p53 genetically and physically interacts with Cdk1 and that p53 proapoptotic role is regulated by the cell cycle status of the cell. We propose a model in which cell cycle progression and p53 proapoptotic activity are molecularly connected to coordinate the appropriate response after DNA damage.
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2
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A fly model establishes distinct mechanisms for synthetic CRISPR/Cas9 sex distorters. PLoS Genet 2020; 16:e1008647. [PMID: 32168334 PMCID: PMC7108745 DOI: 10.1371/journal.pgen.1008647] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 03/31/2020] [Accepted: 02/03/2020] [Indexed: 01/24/2023] Open
Abstract
Synthetic sex distorters have recently been developed in the malaria mosquito, relying on endonucleases that target the X-chromosome during spermatogenesis. Although inspired by naturally-occurring traits, it has remained unclear how they function and, given their potential for genetic control, how portable this strategy is across species. We established Drosophila models for two distinct mechanisms for CRISPR/Cas9 sex-ratio distortion—“X-shredding” and “X-poisoning”—and dissected their target-site requirements and repair dynamics. X-shredding resulted in sex distortion when Cas9 endonuclease activity occurred during the meiotic stages of spermatogenesis but not when Cas9 was expressed from the stem cell stages onwards. Our results suggest that X-shredding is counteracted by the NHEJ DNA repair pathway and can operate on a single repeat cluster of non-essential sequences, although the targeting of a number of such repeats had no effect on the sex ratio. X-poisoning by contrast, i.e. targeting putative haplolethal genes on the X chromosome, induced a high bias towards males (>92%) when we directed Cas9 cleavage to the X-linked ribosomal target gene RpS6. In the case of X-poisoning sex distortion was coupled to a loss in reproductive output, although a dominant-negative effect appeared to drive the mechanism of female lethality. These model systems will guide the study and the application of sex distorters to medically or agriculturally important insect target species. Harmful insect populations can be eliminated for a lack of females if they are made to produce mostly male offspring. There are genes that occur naturally that make males produce mostly sons and, although we don’t know exactly how they work, this appears to coincide with damage to the X-chromosome during the production of sperm. Recently, we showed in a mosquito species that such sex-biasing genes could also be constructed artificially from first principles. To better understand if this works in other species too, we designed and built male-biasing genes of two types in the fruit fly and determined what is needed to for a shift towards males. We show how different ways of cutting the X-chromosome DNA at different times with CRISPR, results in distinct outcomes and started to ask what cellular processes are involved in this. These models will help us to design such genes for the control of insect species that transmit disease or threaten crops.
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3
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Dhivya S, Premkumar K. Nomadic genetic elements contribute to oncogenic translocations: Implications in carcinogenesis. Crit Rev Oncol Hematol 2015; 98:81-93. [PMID: 26548742 DOI: 10.1016/j.critrevonc.2015.10.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 10/05/2015] [Accepted: 10/27/2015] [Indexed: 12/22/2022] Open
Abstract
Chromosomal translocations as molecular signatures have been reported in various malignancies but, the mechanism behind which is largely unknown. Swapping of chromosomal fragments occurs by induction of double strand breaks (DSBs), most of which were initially assumed de novo. However, decoding of human genome proved that transposable elements (TE) might have profound influence on genome integrity. TEs are highly conserved mobile genetic elements that generate DSBs, subsequently resulting in large chromosomal rearrangements. Previously TE insertions were thought to be harmless, but recently gains attention due to the origin of spectrum of post-insertional genomic alterations and subsequent transcriptional alterations leading to development of deleterious effects mainly carcinogenesis. Though the existing knowledge on the cancer-associated TE dynamics is very primitive, exploration of underlying mechanism promises better therapeutic strategies for cancer. Thus, this review focuses on the prevalence of TE in the genome, associated genomic instability upon transposition activation and impact on tumorigenesis.
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Affiliation(s)
- Sridaran Dhivya
- Cancer Genetics and Nanomedicine Laboratory, Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India
| | - Kumpati Premkumar
- Cancer Genetics and Nanomedicine Laboratory, Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
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4
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Lee HB, Sebo ZL, Peng Y, Guo Y. An optimized TALEN application for mutagenesis and screening in Drosophila melanogaster. CELLULAR LOGISTICS 2015. [PMID: 26196022 PMCID: PMC4501208 DOI: 10.1080/21592799.2015.1023423] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Transcription activator-like effector nucleases (TALENs) emerged as powerful tools for locus-specific genome engineering. Due to the ease of TALEN assembly, the key to streamlining TALEN-induced mutagenesis lies in identifying efficient TALEN pairs and optimizing TALEN mRNA injection concentrations to minimize the effort to screen for mutant offspring. Here we present a simple methodology to quantitatively assess bi-allelic TALEN cutting, as well as approaches that permit accurate measures of somatic and germline mutation rates in Drosophila melanogaster. We report that percent lethality from pilot injection of candidate TALEN mRNAs into Lig4 null embryos can be used to effectively gauge bi-allelic TALEN cutting efficiency and occurs in a dose-dependent manner. This timely Lig4-dependent embryonic survival assay also applies to CRISPR/Cas9-mediated targeting. Moreover, the somatic mutation rate of individual G0 flies can be rapidly quantitated using SURVEYOR nuclease and capillary electrophoresis, and germline transmission rate determined by scoring progeny of G0 outcrosses. Together, these optimized methods provide an effective step-wise guide for routine TALEN-mediated gene editing in the fly.
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Key Words
- TALEN
- TALENs, Transcription activator-like effector nucleases; TALEs, TAL effectors; ZFNs, Zinc Finger Nucleases; CRISPR, Clustered Regularly Interspersed Short Palindromic Repeats; Cas9, CRISPR-associated; RVDs, repeat-variable diresidues; DSBs, double-stranded breaks; NHEJ, non-homologous end joining; HR, homologous recombination; RFLP, restriction fragment length polymorphism; HRMA, high resolution melt analysis.
- engineered endonuclease
- genome engineering
- mutagenesis
- screening
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Affiliation(s)
- Han B Lee
- Graduate Program in Neurobiology of Disease; Mayo Graduate School; Mayo Clinic ; Rochester, MN, USA
| | | | - Ying Peng
- Department of Biochemistry and Molecular Biology; Mayo Clinic ; Rochester, MN, USA
| | - Yi Guo
- Department of Biochemistry and Molecular Biology; Mayo Clinic ; Rochester, MN, USA ; Division of Gastroenterology and Hepatology; Mayo Clinic ; Rochester, MN, USA
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5
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Milán M, Clemente-Ruiz M, Dekanty A, Muzzopappa M. Aneuploidy and tumorigenesis in Drosophila. Semin Cell Dev Biol 2014; 28:110-5. [DOI: 10.1016/j.semcdb.2014.03.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/03/2014] [Accepted: 03/10/2014] [Indexed: 12/15/2022]
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6
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Dekanty A, Barrio L, Milán M. Contributions of DNA repair, cell cycle checkpoints and cell death to suppressing the DNA damage-induced tumorigenic behavior of Drosophila epithelial cells. Oncogene 2014; 34:978-85. [DOI: 10.1038/onc.2014.42] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 02/04/2014] [Accepted: 02/07/2014] [Indexed: 12/21/2022]
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7
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Gaivão I, Rodríguez R, Sierra LM. Use of the Comet Assay to Study DNA Repair in Drosophila melanogaster. GENOTOXICITY AND DNA REPAIR 2014. [DOI: 10.1007/978-1-4939-1068-7_23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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8
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Díaz-Castillo C. Females and males contribute in opposite ways to the evolution of gene order in Drosophila. PLoS One 2013; 8:e64491. [PMID: 23696898 PMCID: PMC3655977 DOI: 10.1371/journal.pone.0064491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 04/16/2013] [Indexed: 11/19/2022] Open
Abstract
An intriguing association between the spatial layout of chromosomes within nuclei and the evolution of chromosome gene order was recently uncovered. Chromosome regions with conserved gene order in the Drosophila genus are larger if they interact with the inner side of the nuclear envelope in D. melanogaster somatic cells. This observation opens a new door to understand the evolution of chromosomes in the light of the dynamics of the spatial layout of chromosomes and the way double-strand breaks are repaired in D. melanogaster germ lines. Chromosome regions at the nuclear periphery in somatic cell nuclei relocate to more internal locations of male germ line cell nuclei, which might prefer a gene order-preserving mechanism to repair double-strand breaks. Conversely, chromosome regions at the nuclear periphery in somatic cells keep their location in female germ line cell nuclei, which might be inaccessible for cellular machinery that causes gene order-disrupting chromosome rearrangements. Thus, the gene order stability for genome regions at the periphery of somatic cell nuclei might result from the active repair of double-strand breaks using conservative mechanisms in male germ line cells, and the passive inaccessibility for gene order-disrupting factors at the periphery of nuclei of female germ line cells. In the present article, I find evidence consistent with a DNA break repair-based differential contribution of both D. melanogaster germ lines to the stability/disruption of gene order. The importance of germ line differences for the layout of chromosomes and DNA break repair strategies with regard to other genomic patterns is briefly discussed.
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Webber JL, Rebay I. Chromatin occupancy patterns of the ETS repressor Yan: a mechanism for buffering gene expression against noise? Fly (Austin) 2013; 7:92-8. [PMID: 23575308 DOI: 10.4161/fly.24162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Developmental programs are driven by transcription factors that coordinate precise patterns of gene expression. While recent publications have described the importance of coordinated action of transcriptional activators at multiple cis-regulatory modules or enhancers, the contribution of sequence-specific repressors to overall regulation and robustness of gene expression has been difficult to ascertain. The Ets transcriptional repressor Yan functions as part of a conserved network downstream of receptor tyrosine kinase (RTK) signaling in Drosophila. This network displays switch-like responsiveness to RTK signaling, with the transition from a high-Yan to a low-Yan state induced by mitogen-activated protein kinase (MAPK)-mediated phosphorylation and inactivation of Yan. The ability of Yan to self-associate through a conserved sterile α motif (SAM) is essential for Yan's repressive ability, and has been suggested to allow spreading of Yan repressive complexes along chromatin. Such a mechanism has the potential to confer both signal responsiveness and robustness to the Yan network. To explore this spreading model, we compared the genome-wide chromatin binding profiles of wild-type vs. monomeric Yan. Consistent with the starting prediction, we found that wild type chromatin occupancy at genes encoding crucial developmental regulators and core signaling pathway components occurs as clusters of peaks that "spread" over multiple kilobases. However monomeric Yan, which fails to rescue a yan null mutation and displays significantly impaired repressive ability, exhibits a broadly similar occupancy profile to that of wild-type Yan, with multi-kilobase binding at developmentally important genes. This unexpected result suggests that SAM-mediated self-association does not mediate Yan recruitment to DNA or chromatin spreading, and raises the questions of why developmentally important genes require extensive Yan chromatin occupancy and how SAM-mediated polymerization might contribute to active repressive mechanisms in this context. In this Extra View article we discuss potential mechanisms by which Yan self-association and extended chromatin occupancy may contribute to robust regulation of gene expression.
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Affiliation(s)
- Jemma L Webber
- Ben May Department for Cancer Research, The University of Chicago, Chicago, IL, USA
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10
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Abstract
Repair of meiotic double-strand breaks (DSBs) uses the homolog and recombination to yield crossovers while alternative pathways such as nonhomologous end joining (NHEJ) are suppressed. Our results indicate that NHEJ is blocked at two steps of DSB repair during meiotic prophase: first by the activity of the MCM-like protein MEI-218, which is required for crossover formation, and, second, by Rad51-related proteins SPN-B (XRCC3) and SPN-D (RAD51C), which physically interact and promote homologous recombination (HR). We further show that the MCM-like proteins also promote the activity of the DSB repair checkpoint pathway, indicating an early requirement for these proteins in DSB processing. We propose that when a meiotic DSB is formed in the absence of both MEI-218 and SPN-B or SPN-D, a DSB substrate is generated that can enter the NHEJ repair pathway. Indeed, due to its high error rate, multiple barriers may have evolved to prevent NHEJ activity during meiosis.
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Huefner ND, Mizuno Y, Weil CF, Korf I, Britt AB. Breadth by depth: expanding our understanding of the repair of transposon-induced DNA double strand breaks via deep-sequencing. DNA Repair (Amst) 2011; 10:1023-33. [PMID: 21889425 DOI: 10.1016/j.dnarep.2011.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 07/26/2011] [Indexed: 01/20/2023]
Abstract
The transposases of DNA transposable elements catalyze the excision of the element from the host genome, but are not involved in the repair of the resulting double-strand break. To elucidate the role of various host DNA repair and damage response proteins in the repair of the hairpin-ended double strand breaks (DSBs) generated during excision of the maize Ac element in Arabidopsis thaliana, we deep-sequenced hundreds of thousands of somatic excision products from a variety of repair- or response-defective mutants. We find that each of these repair/response defects negatively affects the preservation of the ends, resulting in an enhanced frequency of deletions, insertions, and inversions at the excision site. The spectra of the resulting repair products demonstrate, not unexpectedly, that the canonical nonhomologous end joining (NHEJ) proteins DNA ligase IV and KU70 play an important role in the repair of the lesion generated by Ac excision. Our data also indicate that auxiliary NHEJ repair proteins such as DNA ligase VI and DNA polymerase lambda are routinely involved in the repair of these lesions. Roles for the damage response kinases ATM and ATR in the repair of transposition-induced DSBs are also discussed.
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Affiliation(s)
- Neil D Huefner
- Department of Plant Biology, University of California, Davis, CA 95616, USA
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12
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Ahmed EA, Philippens MEP, Kal HB, de Rooij DG, de Boer P. Genetic probing of homologous recombination and non-homologous end joining during meiotic prophase in irradiated mouse spermatocytes. Mutat Res 2010; 688:12-18. [PMID: 20167225 DOI: 10.1016/j.mrfmmm.2010.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 01/28/2010] [Accepted: 02/09/2010] [Indexed: 05/28/2023]
Abstract
This study was designed to obtain a better insight into the relative contribution of homologous recombination (HR) and non-homologous end joining (NHEJ) to the repair of radiation-induced DNA double-strand breaks (DSBs) at first meiotic prophase. Early and late pachytene and early diplotene spermatocytes that had completed crossing over were sampled. We studied the kinetics of gamma-H2AX chromatin foci removal after irradiation of mice deficient for HR and mice deficient for NHEJ. Analyzing gamma-H2AX signals in unirradiated RAD54/RAD54B deficient spermatocytes indicated incomplete meiotic recombination repair due to the pronounced increase of gamma-H2AX foci in late prophase primary spermatocytes. In these mice, 8h after irradiation, early pachytene spermatocytes showed a reduction of the numbers of gamma-H2AX foci by 52% compared to 82% in the wild type, the difference being significant. However, after crossing over (in late pachytene and early diplotene), no effect of RAD54/RAD54B deficiency on the reduction of irradiation-induced foci was observed. In NHEJ deficient SCID mice, repair kinetics in early spermatocytes were similar to those in wild type mice. However, 1h after irradiation in late pachytene and early diplotene spermatocytes 1.7 times more foci were found than in wild type mice. This difference might be related to the absence of a DNA-PKcs dependent fast repair component in SCID mice. As subsequent repair is normal, HR likely is taking over. Taken together, the results obtained in RAD54/RAD54B deficient mice and in SCID mice indicate that DSB repair in early pachytene spermatocytes is mainly carried out through HR. In late spermatocytes (late pachytenes and early diplotenes) NHEJ is active. However, probably there is an interplay between these repair pathways and when in late spermatocytes the NHEJ pathway is compromised HR may take over.
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Affiliation(s)
- Emad A Ahmed
- Department of Endocrinology and Metabolism, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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13
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Genetic analysis of zinc-finger nuclease-induced gene targeting in Drosophila. Genetics 2009; 182:641-51. [PMID: 19380480 DOI: 10.1534/genetics.109.101329] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Using zinc-finger nucleases (ZFNs) to cleave the chromosomal target, we have achieved high frequencies of gene targeting in the Drosophila germline. Both local mutagenesis through nonhomologous end joining (NHEJ) and gene replacement via homologous recombination (HR) are stimulated by target cleavage. In this study we investigated the mechanisms that underlie these processes, using materials for the rosy (ry) locus. The frequency of HR dropped significantly in flies homozygous for mutations in spnA (Rad51) or okr (Rad54), two components of the invasion-mediated synthesis-dependent strand annealing (SDSA) pathway. When single-strand annealing (SSA) was also blocked by the use of a circular donor DNA, HR was completely abolished. This indicates that the majority of HR proceeds via SDSA, with a minority mediated by SSA. In flies deficient in lig4 (DNA ligase IV), a component of the major NHEJ pathway, the proportion of HR products rose significantly. This indicates that most NHEJ products are produced in a lig4-dependent process. When both spnA and lig4 were mutated and a circular donor was provided, the frequency of ry mutations was still high and no HR products were recovered. The local mutations produced in these circumstances must have arisen through an alternative, lig4-independent end-joining mechanism. These results show what repair pathways operate on double-strand breaks in this gene targeting system. They also demonstrate that the outcome can be biased toward gene replacement by disabling the major NHEJ pathway and toward simple mutagenesis by interfering with the major HR process.
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14
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Efficient gene targeting in Drosophila by direct embryo injection with zinc-finger nucleases. Proc Natl Acad Sci U S A 2008; 105:19821-6. [PMID: 19064913 DOI: 10.1073/pnas.0810475105] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We report very high gene targeting frequencies in Drosophila by direct embryo injection of mRNAs encoding specific zinc-finger nucleases (ZFNs). Both local mutagenesis via nonhomologous end joining (NHEJ) and targeted gene replacement via homologous recombination (HR) have been achieved in up to 10% of all targets at a given locus. In embryos that are wild type for DNA repair, the products are dominated by NHEJ mutations. In recipients deficient in the NHEJ component, DNA ligase IV, the majority of products arise by HR with a coinjected donor DNA, with no loss of overall efficiency in target modification. We describe the application of the ZFN injection procedure to mutagenesis by NHEJ of 2 new genes in Drosophila melanogaster: coil and pask. Pairs of novel ZFNs designed for targets within those genes led to the production of null mutations at each locus. The injection procedure is much more rapid than earlier approaches and makes possible the generation and recovery of targeted gene alterations at essentially any locus within 2 fly generations.
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15
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Siddique HR, Sharma A, Gupta SC, Murthy RC, Dhawan A, Saxena DK, Chowdhuri DK. DNA damage induced by industrial solid waste leachates in Drosophila melanogaster: a mechanistic approach. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:206-216. [PMID: 18240159 DOI: 10.1002/em.20373] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Genomic stability requires that error-free genetic information be transmitted from generation to generation, a process that is dependent upon efficient DNA repair. Industrial leachates which contain mixtures of diverse chemicals are a major environmental concern. The interaction between these chemicals may have synergistic, antagonistic, or simply additive effects on biological systems. In the present study, the Comet assay was used to measure the DNA damage produced by leachates of solid wastes from flashlight battery, pigment, and tanning factories in the midgut cells and brain ganglia of Drosophila melanogaster mutants deficient in DNA repair proteins. Larvae were allowed to feed for 48 or 72 hr on diets containing 0.1, 0.5, and 2.0% (v/v) of the leachates. Physicochemical analysis run on the solid wastes, leachates, and treated larvae detected elevated levels of heavy metals. Leachates produced significantly greater levels of DNA damage in mutant strains mei41 (deficient in cell cycle check point protein), mus201 (deficient in excision repair protein), mus308 (deficient in postreplication repair protein), and rad54 (deficient in double strand break repair protein) than in the OregonR(+) wild-type strain. Larvae of the ligaseIV mutant (deficient in double strand break repair protein) were hypersensitive only to the pigment plant waste leachate. Conversely, the dnase2 mutant (deficient in protein responsible for degrading fragmented DNA) was more sensitive to DNA damage induction from the flashlight battery and tannery waste leachates. Our data demonstrate that repair of DNA damage in organisms exposed to leachates is dependent upon several DNA repair proteins, indicative of the involvement of multiple overlapping repair pathways. The study further suggests the usefulness of the Comet assay for studying the mechanisms of DNA repair in Drosophila.
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Affiliation(s)
- Hifzur R Siddique
- Embryotoxicology Section, Industrial Toxicology Research Centre, Lucknow, Uttar Pradesh, India
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16
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Abstract
The study of DNA double-strand break (DSB) repair has been greatly facilitated by the use of rare-cutting endonucleases, which induce a break precisely at their cut sites that can be strategically placed in the genome. We previously established such a system in Drosophila and showed that the yeast I-SceI enzyme cuts efficiently in Drosophila cells and those breaks are effectively repaired by conserved mechanisms. In this study, we determined the genetic requirements for the repair of this I-SceI-induced DSB in the germline. We show that Drosophila Rad51 and Rad54 are both required for homologous repair by gene conversion, but are dispensable for single-strand annealing repair. We provided evidence suggesting that Rad51 is more stringently required than Rad54 for intersister gene conversion. We uncovered a significant role of DNA ligase IV in nonhomologous end joining. We conducted a screen for candidate mutations affecting DSB repair and discovered novel mutations in genes that include mutagen sensitive 206, single-strand annealing reducer, and others. In addition, we demonstrated an intricate balance among different repair pathways in which the cell differentially utilizes repair mechanisms in response to both changes in the genomic environment surrounding the break and deficiencies in one or the other repair pathways.
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Affiliation(s)
- Debbie S Wei
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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17
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Johnson-Schlitz DM, Flores C, Engels WR. Multiple-pathway analysis of double-strand break repair mutations in Drosophila. PLoS Genet 2007; 3:e50. [PMID: 17432935 PMCID: PMC1851981 DOI: 10.1371/journal.pgen.0030050] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Accepted: 02/20/2007] [Indexed: 11/19/2022] Open
Abstract
The analysis of double-strand break (DSB) repair is complicated by the existence of several pathways utilizing a large number of genes. Moreover, many of these genes have been shown to have multiple roles in DSB repair. To address this complexity we used a repair reporter construct designed to measure multiple repair outcomes simultaneously. This approach provides estimates of the relative usage of several DSB repair pathways in the premeiotic male germline of Drosophila. We applied this system to mutations at each of 11 repair loci plus various double mutants and altered dosage genotypes. Most of the mutants were found to suppress one of the pathways with a compensating increase in one or more of the others. Perhaps surprisingly, none of the single mutants suppressed more than one pathway, but they varied widely in how the suppression was compensated. We found several cases in which two or more loci were similar in which pathway was suppressed while differing in how this suppression was compensated. Taken as a whole, the data suggest that the choice of which repair pathway is used for a given DSB occurs by a two-stage "decision circuit" in which the DSB is first placed into one of two pools from which a specific pathway is then selected.
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Affiliation(s)
- Dena M Johnson-Schlitz
- Department of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Carlos Flores
- Department of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - William R Engels
- Department of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
- * To whom correspondence should be addressed. E-mail:
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18
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Abstract
The ability of a cell to sense and respond to DNA damage is essential for genome stability. An important aspect of the response is arrest of the cell cycle, presumably to allow time for repair. Ataxia telangiectasia mutated (ATM) and ATR are essential for such cell-cycle control, but some observations suggest that they also play a direct role in DNA repair. The Drosophila ortholog of ATR, MEI-41, mediates the DNA damage-dependent G2-M checkpoint. We examined the role of MEI-41 in repair of double-strand breaks (DSBs) induced by P-element excision. We found that mei-41 mutants are defective in completing the later steps of homologous recombination repair, but have no defects in end-joining repair. We hypothesized that these repair defects are the result of loss of checkpoint control. To test this, we genetically reduced mitotic cyclin levels and also examined repair in grp (DmChk1) and lok (DmChk2) mutants. Our results suggest that a significant component of the repair defects is due to loss of MEI-41-dependent cell cycle regulation. However, this does not account for all of the defects we observed. We propose a novel role for MEI-41 in DSB repair, independent of the Chk1/Chk2-mediated checkpoint response.
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Affiliation(s)
- Jeannine R LaRocque
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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19
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Robert V, Bessereau JL. Targeted engineering of the Caenorhabditis elegans genome following Mos1-triggered chromosomal breaks. EMBO J 2006; 26:170-83. [PMID: 17159906 PMCID: PMC1782371 DOI: 10.1038/sj.emboj.7601463] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 11/02/2006] [Indexed: 01/08/2023] Open
Abstract
The Drosophila element Mos1 is a class II transposon, which moves by a 'cut-and-paste' mechanism and can be experimentally mobilized in the Caenorhabditis elegans germ line. Here, we triggered the excision of identified Mos1 insertions to create chromosomal breaks at given sites and further manipulate the broken loci. Double-strand break (DSB) repair could be achieved by gene conversion using a transgene containing sequences homologous to the broken chromosomal region as a repair template. Consequently, mutations engineered in the transgene could be copied to a specific locus at high frequency. This pathway was further characterized to develop an efficient tool--called MosTIC--to manipulate the C. elegans genome. Analysis of DSB repair during MosTIC experiments demonstrated that DSBs could also be sealed by end-joining in the germ line, independently from the evolutionarily conserved Ku80 and ligase IV factors. In conjunction with a publicly available Mos1 insertion library currently being generated, MosTIC will provide a general tool to customize the C. elegans genome.
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Affiliation(s)
- Valérie Robert
- ENS, Biologie cellulaire de la synapse, Paris, France; Inserm, U789, Paris, France
| | - Jean-Louis Bessereau
- ENS, Biologie cellulaire de la synapse, Paris, France; Inserm, U789, Paris, France
- Ecole Normale Supérieure, INSERM U789, 46 Rue d'Ulm, Paris 75005, France. Tel.: +33 1 44 32 23 05; Fax: +33 1 44 32 36 54; E-mail:
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Abstract
The regulation of chromatin structure is of fundamental importance for many DNA-based processes in eukaryotes. Activation or repression of gene transcription or DNA replication depends on enzymes which can generate the appropriate chromatin environment. Several of these enzymes utilize the energy of ATP hydrolysis to alter nucleosome structure. In recent years our understanding of the multisubunit complexes within which they function, their mechanisms of action, their regulation and their in-vivo roles has increased. Much of what we have learned has been gleaned from studies in Drosophila melanogaster. Here we will review what we know about the main classes of ATP-dependent chromatin remodelers in Drosophila.
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Affiliation(s)
- Karim Bouazoune
- Massachusetts General Hospital, Department of Molecular Biology, Harvard Medical School, Department of Genetics, 185 Cambridge Street, Boston, MA 02114, USA
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McCaffrey R, St Johnston D, González-Reyes A. Drosophila mus301/spindle-C encodes a helicase with an essential role in double-strand DNA break repair and meiotic progression. Genetics 2006; 174:1273-85. [PMID: 16888338 PMCID: PMC1667076 DOI: 10.1534/genetics.106.058289] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
mus301 was identified independently in two genetic screens, one for mutants hypersensitive to chemical mutagens and another for maternal mutants with eggshell defects. mus301 is required for the proper specification of the oocyte and for progression through meiosis in the Drosophila ovary. We have cloned mus301 and show that it is a member of the Mus308 subfamily of ATP-dependent helicases and the closest homolog of human and mouse HEL308. Functional analyses demonstrate that Mus301 is involved in chromosome segregation in meiosis and in the repair of double-strand-DNA breaks in both meiotic and mitotic cells. Most of the oogenesis defects of mus301 mutants are suppressed by mutants in the checkpoint kinase Mei41 and in MeiW68, the Spo11 homolog that is thought to generate the dsDNA breaks that initiate recombination, indicating that these phenotypes are caused by activation of the DNA damage checkpoint in response to unrepaired Mei-W68-induced dsDNA breaks. However, neither mei-W68 nor mei-41 rescue the defects in oocyte specification of mus301 mutants, suggesting that this helicase has another function in oocyte selection that is independent from its role in meiotic recombination.
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Affiliation(s)
- Ruth McCaffrey
- MRC Laboratory of Molecular Biology, The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge CB2 1QR, United Kingdom
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Preston CR, Flores CC, Engels WR. Differential usage of alternative pathways of double-strand break repair in Drosophila. Genetics 2005; 172:1055-68. [PMID: 16299390 PMCID: PMC1456205 DOI: 10.1534/genetics.105.050138] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Double-strand DNA breaks can be repaired by any of several alternative mechanisms that differ greatly in the nature of the final repaired products. We used a reporter construct, designated "Repair reporter 3" (Rr3), to measure the relative usage of these pathways in Drosophila germ cells. The method works by creating a double-strand break at a specific location such that expression of the red fluorescent protein, DsRed, in the next generation can be used to infer the frequency at which each pathway was used. A key feature of this approach is that most data come from phenotypic scoring, thus allowing large sample sizes and considerable precision in measurements. Specifically, we measured the proportion of breaks repaired by (1) conversion repair, (2) nonhomologous end joining (NHEJ), or (3) single-strand annealing (SSA). For conversion repair, the frequency of mitotic crossing over in the germ line indicates the relative prevalence of repair by double Holliday junction (DHJ) formation vs. the synthesis-dependent strand annealing (SDSA) pathway. We used this method to show that breaks occurring early in germ-line development were much more frequently repaired via single-strand annealing and much less likely to be repaired by end joining compared with identical breaks occurring later in development. Conversion repair was relatively rare when breaks were made either very early or very late in development, but was much more frequent in between. Significantly, the changes in relative usage occurred in a compensatory fashion, such that an increase in one pathway was accompanied by decreases in others. This negative correlation is interpreted to mean that the pathways for double-strand break repair compete with each other to handle a given breakage event.
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Affiliation(s)
- Christine R Preston
- Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706, USA
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