1
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Herriage HC, Huang YT, Calvi BR. The antagonistic relationship between apoptosis and polyploidy in development and cancer. Semin Cell Dev Biol 2024; 156:35-43. [PMID: 37331841 PMCID: PMC10724375 DOI: 10.1016/j.semcdb.2023.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/23/2023] [Accepted: 05/30/2023] [Indexed: 06/20/2023]
Abstract
One of the important functions of regulated cell death is to prevent cells from inappropriately acquiring extra copies of their genome, a state known as polyploidy. Apoptosis is the primary cell death mechanism that prevents polyploidy, and defects in this apoptotic response can result in polyploid cells whose subsequent error-prone chromosome segregation are a major contributor to genome instability and cancer progression. Conversely, some cells actively repress apoptosis to become polyploid as part of normal development or regeneration. Thus, although apoptosis prevents polyploidy, the polyploid state can actively repress apoptosis. In this review, we discuss progress in understanding the antagonistic relationship between apoptosis and polyploidy in development and cancer. Despite recent advances, a key conclusion is that much remains unknown about the mechanisms that link apoptosis to polyploid cell cycles. We suggest that drawing parallels between the regulation of apoptosis in development and cancer could help to fill this knowledge gap and lead to more effective therapies.
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Affiliation(s)
- Hunter C Herriage
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Yi-Ting Huang
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Brian R Calvi
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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2
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Colon Plaza S, Su TT. Ionizing radiation induces cells with past caspase activity that contribute to the adult organ in Drosophila and show reduced Loss of Heterozygosity. Cell Death Discov 2024; 10:6. [PMID: 38182576 PMCID: PMC10770159 DOI: 10.1038/s41420-023-01769-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 12/01/2023] [Accepted: 12/07/2023] [Indexed: 01/07/2024] Open
Abstract
There is increasing recognition that cells may activate apoptotic caspases but not die, instead displaying various physiologically relevant consequences. Mechanisms that underlie the life-or-death decision in a cell that has activated apoptotic caspases, however, are incompletely understood. By optimizing a published reporter for past caspase activity, we were able to visualize cells that survived caspase activation specifically after exposure to ionizing radiation in Drosophila larval wing discs. We found that cells with X-ray-induced past active caspases (XPAC) did not arise at random but were born at specific locations within the developing wing imaginal discs of Drosophila larvae. Inhibiting key components of the apoptotic pathway decreased XPAC number, suggesting that apoptotic signaling is needed to induce XPAC cells. Yet, XPAC cells appeared in stereotypical patterns that did not follow the pattern of IR-induced apoptosis, suggesting additional controls at play. Functional testing identified the contribution of wingless (Drosophila Wnt1) and Ras signaling to the prevalence of XPAC cells. Furthermore, by following irradiated larvae into adulthood, we found that XPAC cells contribute to the adult wing. To address the relationship between XPAC and genome stability, we combined a reporter for past caspase activity with mwh, an adult marker for Loss of Heterozygosity (LOH). We found a lower incidence of LOH among XPAC compared to cells that did not activate the reporter for past caspase activity. In addition, at time points when wing disc cells are finishing DNA repair, XPAC cells show an anti-correlation with cells with unrepaired IR-induced double-stranded breaks. Our data suggest that non-lethal caspase activity safeguards the genome by facilitating DNA repair and reducing LOH after transient exposure to X-rays. These results identify a physiological role for non-lethal caspase activity during recovery from radiation damage.
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Affiliation(s)
- Sarah Colon Plaza
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309-0347, USA
| | - Tin Tin Su
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309-0347, USA.
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3
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Brown J, Su TT. E2F1, DIAP1, and the presence of a homologous chromosome promote while JNK inhibits radiation-induced loss of heterozygosity in Drosophila melanogaster. Genetics 2024; 226:iyad192. [PMID: 37874851 PMCID: PMC10763536 DOI: 10.1093/genetics/iyad192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 08/25/2023] [Accepted: 10/04/2023] [Indexed: 10/26/2023] Open
Abstract
Loss of heterozygosity (LOH) can occur when a heterozygous mutant cell loses the remaining wild-type allele to become a homozygous mutant. LOH can have physiological consequences if, for example, the affected gene encodes a tumor suppressor. We used fluorescent reporters to study the mechanisms of LOH induction by X-rays, a type of ionizing radiation (IR), in Drosophila melanogaster larval wing discs. IR is used to treat more than half of patients with cancer, so understanding its effects is of biomedical relevance. Quantitative analysis of IR-induced LOH at different positions between the telomere and the centromere on the X chromosome showed a strong sex dependence and the need for a recombination-proficient homologous chromosome, whereas, paradoxically, position along the chromosome made little difference in LOH incidence. We propose that published data documenting high recombination frequency within centromeric heterochromatin on the X chromosome can explain these data. Using a focused screen, we identified E2F1 as a key promotor of LOH and further testing suggests a mechanism involving its role in cell-cycle regulation. We leveraged the loss of a transcriptional repressor through LOH to express transgenes specifically in cells that have already acquired LOH. This approach identified JNK signaling and apoptosis as key determinants of LOH maintenance. These studies reveal previously unknown mechanisms for the generation and elimination of cells with chromosome aberrations after exposure to IR.
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Affiliation(s)
- Jeremy Brown
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309-0347, USA
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, 13001 E. 17th Pl., Aurora, CO 80045, USA
| | - Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309-0347, USA
- University of Colorado Cancer Center, Anschutz Medical Campus, 13001 E. 17th Pl., Aurora, CO 80045, USA
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4
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Brown J, Su TT. E2F1 promotes, JNK and DIAP1 inhibit, and chromosomal position has little effect on radiation-induced Loss of Heterozygosity in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.540084. [PMID: 37214983 PMCID: PMC10197609 DOI: 10.1101/2023.05.09.540084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Loss of Heterozygosity (LOH) can occur when a heterozygous mutant cell loses the remaining wild type allele to become a homozygous mutant. LOH can have physiological consequences if, for example, the affected gene encodes a tumor suppressor. We used two fluorescent reporters to study mechanisms of LOH induction by X-rays, a type of ionizing radiation (IR), in Drosophila larval wing discs. IR is used to treat more than half of cancer patients, so understanding its effects is of biomedical relevance. We report that IR-induced LOH does not correlate with the chromosomal position of the LOH locus, unlike previously shown for spontaneously occurring LOH. Like spontaneous LOH, however, IR-induced LOH of X-linked loci shows a sex-dependence, occurring predominately in females. A focused genetic screen identified E2F1 as a key promotor of LOH and further testing suggests a mechanism involving its role in cell cycle regulation rather than apoptosis. We combined the QF/QS LOH reporter with QUAS-transgenes to manipulate gene function after LOH induction. This approach identified JNK signaling and apoptosis as key determinants of LOH maintenance. These studies reveal previously unknown mechanisms for generation and maintenance of cells with chromosome aberrations after exposure to IR.
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5
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Lama J, Srivastav S, Tasnim S, Hubbard D, Hadjipanteli S, Smith BR, Macdonald SJ, Green L, Kelleher ES. Genetic variation in P-element dysgenic sterility is associated with double-strand break repair and alternative splicing of TE transcripts. PLoS Genet 2022; 18:e1010080. [PMID: 36477699 PMCID: PMC9762592 DOI: 10.1371/journal.pgen.1010080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 12/19/2022] [Accepted: 11/02/2022] [Indexed: 12/12/2022] Open
Abstract
The germline mobilization of transposable elements (TEs) by small RNA mediated silencing pathways is conserved across eukaryotes and critical for ensuring the integrity of gamete genomes. However, genomes are recurrently invaded by novel TEs through horizontal transfer. These invading TEs are not targeted by host small RNAs, and their unregulated activity can cause DNA damage in germline cells and ultimately lead to sterility. Here we use hybrid dysgenesis-a sterility syndrome of Drosophila caused by transposition of invading P-element DNA transposons-to uncover host genetic variants that modulate dysgenic sterility. Using a panel of highly recombinant inbred lines of Drosophila melanogaster, we identified two linked quantitative trait loci (QTL) that determine the severity of dysgenic sterility in young and old females, respectively. We show that ovaries of fertile genotypes exhibit increased expression of splicing factors that suppress the production of transposase encoding transcripts, which likely reduces the transposition rate and associated DNA damage. We also show that fertile alleles are associated with decreased sensitivity to double-stranded breaks and enhanced DNA repair, explaining their ability to withstand high germline transposition rates. Together, our work reveals a diversity of mechanisms whereby host genotype modulates the cost of an invading TE, and points to genetic variants that were likely beneficial during the P-element invasion.
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Affiliation(s)
- Jyoti Lama
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Satyam Srivastav
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Sadia Tasnim
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Donald Hubbard
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Savana Hadjipanteli
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Brittny R. Smith
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Stuart J. Macdonald
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Llewellyn Green
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Erin S. Kelleher
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
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6
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Baonza A, Tur-Gracia S, Pérez-Aguilera M, Estella C. Regulation and coordination of the different DNA damage responses in Drosophila. Front Cell Dev Biol 2022; 10:993257. [PMID: 36147740 PMCID: PMC9486394 DOI: 10.3389/fcell.2022.993257] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/10/2022] [Indexed: 11/17/2022] Open
Abstract
Cells have evolved mechanisms that allow them to respond to DNA damage to preserve genomic integrity and maintain tissue homeostasis. These responses include the activation of the cell cycle checkpoints and the repair mechanisms or the induction of apoptosis that eventually will eliminate damaged cells. These “life” vs. “death” decisions differ depending on the cell type, stages of development, and the proliferation status of the cell. The apoptotic response after DNA damage is of special interest as defects in its induction could contribute to tumorigenesis or the resistance of cancer cells to therapeutic agents such as radiotherapy. Multiples studies have elucidated the molecular mechanisms that mediate the activation of the DNA damage response pathway (DDR) and specifically the role of p53. However, much less is known about how the different cellular responses such as cell proliferation control and apoptosis are coordinated to maintain tissue homeostasis. Another interesting question is how the differential apoptotic response to DNA damage is regulated in distinct cell types. The use of Drosophila melanogaster as a model organism has been fundamental to understand the molecular and cellular mechanisms triggered by genotoxic stress. Here, we review the current knowledge regarding the cellular responses to ionizing radiation as the cause of DNA damage with special attention to apoptosis in Drosophila: how these responses are regulated and coordinated in different cellular contexts and in different tissues. The existence of intrinsic mechanisms that might attenuate the apoptotic pathway in response to this sort of DNA damage may well be informative for the differences in the clinical responsiveness of tumor cells after radiation therapy.
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7
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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: 16] [Impact Index Per Article: 8.0] [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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8
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Colon-Plaza S, Su TT. Non-Apoptotic Role of Apoptotic Caspases in the Drosophila Nervous System. Front Cell Dev Biol 2022; 10:839358. [PMID: 35223857 PMCID: PMC8863954 DOI: 10.3389/fcell.2022.839358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 01/14/2022] [Indexed: 01/11/2023] Open
Abstract
An increasing number of studies demonstrate that cells can activate apoptotic caspases but not die and, instead, display profound changes in cellular structure and function. In this minireview, we will discuss observations in the nervous system of Drosophila melanogaster that illustrate non-apoptotic roles of apoptotic caspases. We will preface these examples with similar observations in other experimental systems and end with a discussion of how apoptotic caspase activity might be constrained to provide non-lethal functions without killing the cell.
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Affiliation(s)
- Sarah Colon-Plaza
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States
| | - Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States
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9
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Nguyen TTN, Shim J, Song YH. Chk2-p53 and JNK in irradiation-induced cell death of hematopoietic progenitors and differentiated cells in Drosophila larval lymph gland. Biol Open 2021; 10:271116. [PMID: 34328173 PMCID: PMC8411456 DOI: 10.1242/bio.058809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/22/2021] [Indexed: 11/20/2022] Open
Abstract
Ionizing radiation (IR) induces DNA double-strand breaks that activate the DNA damage response (DDR), which leads to cell cycle arrest, senescence, or apoptotic cell death. Understanding the DDR of stem cells is critical to tissue homeostasis and the survival of the organism. Drosophila hematopoiesis serves as a model system for sensing stress and environmental changes; however, their response to DNA damage remains largely unexplored. The Drosophila lymph gland is the larval hematopoietic organ, where stem-like progenitors proliferate and differentiate into mature blood cells called hemocytes. We found that apoptotic cell death was induced in progenitors and hemocytes after 40 Gy irradiation, with progenitors showing more resistance to IR-induced cell death compared to hemocytes at a lower dose. Furthermore, we found that Drosophila ATM (tefu), Chk2 (lok), p53, and reaper were necessary for IR-induced cell death in the progenitors. Notably, IR-induced cell death in mature hemocytes required tefu, Drosophila JNK (bsk), and reaper, but not lok or p53. In summary, we found that DNA damage induces apoptotic cell death in the late third instar larval lymph gland and identified lok/p53-dependent and -independent cell death pathways in progenitors and mature hemocytes, respectively.
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Affiliation(s)
- Tram Thi Ngoc Nguyen
- Department of Biomedical Gerontology, Hallym University, Chuncheon, Gangwon-do 24252, Republic of Korea.,Ilsong Institute of Life Science, Hallym University, Seoul 07247, Republic of Korea
| | - Jiwon Shim
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Young-Han Song
- Department of Biomedical Gerontology, Hallym University, Chuncheon, Gangwon-do 24252, Republic of Korea.,Ilsong Institute of Life Science, Hallym University, Seoul 07247, Republic of Korea
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10
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Abstract
Drosophila melanogaster remains a foremost genetic model to study basic cell biological processes in the context of multi-cellular development. In such context, the behavior of one cell can influence another. Non-autonomous signaling among cells occurs throughout metazoan development and disease, and is too vast to be covered by a single review. I will focus here on non-autonomous signaling events that occur in response to cell death in the larval epithelia and affect the life-death decision of surviving cells. I will summarize the use of Drosophila to study cell death-induced proliferation, apoptosis-induced apoptosis, and apoptosis-induced survival signaling. Key insights from Drosophila will be discussed in the context of analogous processes in mammalian development and cancer biology.
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Affiliation(s)
- Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309-0347, USA
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11
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Su TT. Non-autonomous consequences of cell death and other perks of being metazoan. AIMS GENETICS 2021. [DOI: 10.3934/genet.2015.1.54] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abstract
Drosophila melanogaster remains a foremost genetic model to study basic cell biological processes in the context of multi-cellular development. In such context, the behavior of one cell can influence another. Non-autonomous signaling among cells occurs throughout metazoan development and disease, and is too vast to be covered by a single review. I will focus here on non-autonomous signaling events that occur in response to cell death in the larval epithelia and affect the life-death decision of surviving cells. I will summarize the use of Drosophila to study cell death-induced proliferation, apoptosis-induced apoptosis, and apoptosis-induced survival signaling. Key insights from Drosophila will be discussed in the context of analogous processes in mammalian development and cancer biology.
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Affiliation(s)
- Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309-0347, USA
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12
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Ji Z, Chuen J, Kiparaki M, Baker N. Cell competition removes segmental aneuploid cells from Drosophila imaginal disc-derived tissues based on ribosomal protein gene dose. eLife 2021; 10:61172. [PMID: 33847264 PMCID: PMC8043752 DOI: 10.7554/elife.61172] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 03/08/2021] [Indexed: 12/22/2022] Open
Abstract
Aneuploidy causes birth defects and miscarriages, occurs in nearly all cancers and is a hallmark of aging. Individual aneuploid cells can be eliminated from developing tissues by unknown mechanisms. Cells with ribosomal protein (Rp) gene mutations are also eliminated, by cell competition with normal cells. Because Rp genes are spread across the genome, their copy number is a potential marker for aneuploidy. We found that elimination of imaginal disc cells with irradiation-induced genome damage often required cell competition genes. Segmentally aneuploid cells derived from targeted chromosome excisions were eliminated by the RpS12-Xrp1 cell competition pathway if they differed from neighboring cells in Rp gene dose, whereas cells with normal doses of the Rp and eIF2γ genes survived and differentiated adult tissues. Thus, cell competition, triggered by differences in Rp gene dose between cells, is a significant mechanism for the elimination of aneuploid somatic cells, likely to contribute to preventing cancer. Aneuploid cells emerge when cellular division goes awry and a cell ends up with the wrong number of chromosomes, the tiny genetic structures carrying the instructions that control life’s processes. Aneuploidy can lead to fatal conditions during development, and to cancer in an adult organism. A safety mechanism may exist that helps the body to detect and remove these cells. Yet, exactly this happens is still poorly understood: in particular, it is unclear how cells manage to ‘count’ their chromosomes. One way they could do so is through the ribosomes, the molecular ‘factories’ that create the building blocks required for life. In a cell, every chromosome carries genes that code for the proteins (known as Rps) forming ribosomes. Aneuploidy will alter the number of Rp genes, and in turn the amount and type of Rps the cell produces, so that ribosomes and the genes for Rps could act as a ‘readout’ of aneuploidy. Ji et al set out to test this theory in fruit flies. The first experiment used a genetic manipulation technique called site-specific recombination to remove parts of chromosomes from cells in the developing eye and wing. Cells which retained all their Rp genes survived, while those that were missing some usually died – but only when the surrounding cells were normal. In this situation, healthy cells eliminated their damaged neighbours through a process known as cell competition. A second experiment, using radiation as an alternative method of damaging chromosomes, also gave similar results. The work by Ji et al. reveals how the body can detect and eliminate aneuploid cells, potentially before they can cause harm. If the same mechanism applies in humans, boosting cell competition may, one day, helps to combat diseases like cancer.
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Affiliation(s)
- Zhejun Ji
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Jacky Chuen
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Marianthi Kiparaki
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Nicholas Baker
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
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13
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Brown J, Bush I, Bozon J, Su TT. Cells with loss-of-heterozygosity after exposure to ionizing radiation in Drosophila are culled by p53-dependent and p53-independent mechanisms. PLoS Genet 2020; 16:e1009056. [PMID: 33075096 PMCID: PMC7595702 DOI: 10.1371/journal.pgen.1009056] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 10/29/2020] [Accepted: 08/17/2020] [Indexed: 11/18/2022] Open
Abstract
Loss of Heterozygosity (LOH) typically refers to a phenomenon in which diploid cells that are heterozygous for a mutant allele lose their wild type allele through mutations. LOH is implicated in oncogenesis when it affects the remaining wild type copy of a tumor suppressor. Drosophila has been a useful model to identify genes that regulate the incidence of LOH, but most of these studies use adult phenotypic markers such as multiple wing hair (mwh). Here, we describe a cell-autonomous fluorescence-based system that relies on the QF/QS transcriptional module to detect LOH, which may be used in larval, pupal and adult stages and in conjunction with the GAL4/UAS system. Using the QF/QS system, we were able to detect the induction of cells with LOH by X-rays in a dose-dependent manner in the larval wing discs, and to monitor their fate through subsequent development in pupa and adult stages. We tested the genetic requirement for changes in LOH, using both classical mutants and GAL4/UAS-mediated RNAi. Our results identify two distinct culling phases that eliminate cells with LOH, one in late larval stages and another in the pupa. The two culling phases are genetically separable, showing differential requirement for pro-apoptotic genes of the H99 locus and transcription factor Srp. A direct comparison of mwh LOH and QF/QS LOH suggests that cells with different LOH events are distinguished from each other in a p53-dependent manner and are retained to different degrees in the final adult structure. These studies reveal previously unknown mechanisms for the elimination of cells with chromosome aberrations.
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Affiliation(s)
- Jeremy Brown
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO, United States of America
| | - Inle Bush
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO, United States of America
| | - Justine Bozon
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO, United States of America
| | - Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, 347 UCB, University of Colorado, Boulder, CO, United States of America
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14
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Nakajima K, Gao T, Kume K, Iwata H, Hirai S, Omachi C, Tomita J, Ogino H, Naito M, Shibamoto Y. Fruit Fly, Drosophila melanogaster, as an In Vivo Tool to Study the Biological Effects of Proton Irradiation. Radiat Res 2020; 194:143-152. [PMID: 32845992 DOI: 10.1667/rade-20-00006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 03/27/2020] [Indexed: 11/03/2022]
Abstract
The clinical superiority of proton therapy over photon therapy has recently gained recognition; however, the biological effects of proton therapy remain poorly understood. The lack of in vivo evidence is especially important. Therefore, the goal of this study was to validate the usefulness of Drosophila melanogaster as an alternative tool in proton radiobiology. To determine whether the comparative biological effects of protons and X rays are detectable in Drosophila, we assessed their influence on survival and mRNA expression. Postirradiation observation revealed that protons inhibited their development and reduced the overall survival rates more effectively than X rays. The relative biological effectiveness of the proton beams compared to the X rays estimated from the 50% lethal doses was 1.31. At 2 or 24 h postirradiation, mRNA expression analysis demonstrated that the expression patterns of several genes (such as DNA-repair-, apoptosis- and angiogenesis-related genes) followed different time courses depending on radiation type. Moreover, our trials suggested that the knockdown of individual genes by the GAL4/UAS system changes the radiosensitivity in a radiation type-specific manner. We confirmed this Drosophila model to be considerably useful to evaluate the findings from in vitro studies in an in vivo system. Furthermore, this model has a potential to elucidate more complex biological mechanisms underlying proton irradiation.
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Affiliation(s)
- Koichiro Nakajima
- Departments of Radiation Oncology.,Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - TianXiang Gao
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Kazuhiko Kume
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hiromitsu Iwata
- Departments of Radiation Oncology.,Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Shuichi Hirai
- Department of Anatomy, Aichi Medical University, Nagakute, Japan
| | - Chihiro Omachi
- Departments of Radiation Oncology and Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Japan
| | - Jun Tomita
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hiroyuki Ogino
- Departments of Radiation Oncology.,Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Munekazu Naito
- Department of Anatomy, Aichi Medical University, Nagakute, Japan
| | - Yuta Shibamoto
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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15
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Puspitasari A, Yamazaki H, Kawamura H, Nakano T, Takahashi A, Shirao T, Held KD. X-irradiation of developing hippocampal neurons causes changes in neuron population phenotypes, dendritic morphology and synaptic protein expression in surviving neurons at maturity. Neurosci Res 2019; 160:11-24. [PMID: 31711782 DOI: 10.1016/j.neures.2019.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/16/2019] [Accepted: 11/06/2019] [Indexed: 01/02/2023]
Abstract
The effects of X-irradiation on developing neurons and their functions are unclear. We used primary cultures of mouse hippocampal neurons to investigate the effects of X-irradiation on cell death in developing neurons by analyzing caspase-3, MAP2 and DAPI-labeled cells, and the phenotypes and function of surviving neurons, by examining GAD67-positive cells as a GABAergic marker, and the synaptic markers synapsin 1, drebrin and PSD-95 through its maturation. One-day in vitro (DIV 1) cells were exposed to 0.5 Gy or 1 Gy of X-rays. A significant increase in the percentage of activated caspase-3, a decrease in the number of MAP2/DAPI-positive cells and change in the percentage of GAD67 positive neurons, compared with sham controls, were found 6 days after 1 Gy and 13 days after 0.5 Gy of X-rays. The expression of PSD-95 and drebrin, as well as drebrin clusters, in the remaining neurons was decreased at DIV 21, in both 0.5 Gy and on 1 Gy-irradiation there was a reduced number of dendritic intersection as well. Together, our findings show that 0.5 Gy and 1 Gy of X-irradiation at DIV 1 not only causes neuronal cell death but elicits an increase in the percentage of inhibitory neurons, changes in the dendrites and decrease in expression of important synaptic proteins in the surviving neurons at maturity 3 weeks after exposure.
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Affiliation(s)
| | - Hiroyuki Yamazaki
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Hidemasa Kawamura
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takashi Nakano
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Akihisa Takahashi
- Gunma University Heavy Ion Medical Center, Maebashi, Graduate School of Medicine, Gunma, Japan
| | - Tomoaki Shirao
- Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Kathryn D Held
- Gunma University Initiative for Advanced Research, Maebashi, Japan; Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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16
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Park JH, Nguyen TTN, Lee EM, Castro-Aceituno V, Wagle R, Lee KS, Choi J, Song YH. Role of p53 isoforms in the DNA damage response during Drosophila oogenesis. Sci Rep 2019; 9:11473. [PMID: 31391501 PMCID: PMC6685966 DOI: 10.1038/s41598-019-47913-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/26/2019] [Indexed: 01/08/2023] Open
Abstract
The tumor suppressor p53 is involved in the DNA damage response and induces cell cycle arrest or apoptosis upon DNA damage. Drosophila p53 encodes two isoforms, p53A and p53B, that induce apoptosis in somatic cells. To investigate the roles of Drosophila p53 isoforms in female germline cells, the DNA damage response was analyzed in the adult ovary. Early oogenesis was sensitive to irradiation and lok-, p53-, and hid-dependent cell death occurred rapidly after both low- and high-dose irradiation. Both p53 isoforms were responsible for this cell death. On the other hand, delayed cell death in mid-oogenesis was induced at a low level only after high-dose irradiation in a p53-independent manner. The daily egg production, which did not change after low-dose irradiation, was severely reduced after high-dose irradiation in p53 mutant females due to the loss of germline stem cells. When the p53A or p53B isoform was expressed in the germline cells in the p53 mutant females at levels that do not affect normal oogenesis, p53A, but not p53B, restored the fertility of the irradiated female. In summary, moderate expression of p53A is critical to maintain the function of germline stem cells during normal oogenesis as well as after high-dose irradiation.
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Affiliation(s)
- Ji-Hong Park
- Department of Biomedical Gerontology, Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Tram Thi Ngoc Nguyen
- Department of Biomedical Gerontology, Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Eun-Mi Lee
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea
| | | | - Ram Wagle
- Department of Biomedical Gerontology, Hallym University, Chuncheon, Gangwon-do, Republic of Korea
| | - Kwang-Soon Lee
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea
| | - Juyoung Choi
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea
| | - Young-Han Song
- Department of Biomedical Gerontology, Hallym University, Chuncheon, Gangwon-do, Republic of Korea. .,Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Republic of Korea.
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17
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Khan C, Muliyil S, Rao BJ. Genome Damage Sensing Leads to Tissue Homeostasis in Drosophila. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2019; 345:173-224. [PMID: 30904193 DOI: 10.1016/bs.ircmb.2018.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA repair is a critical cellular process required for the maintenance of genomic integrity. It is now well appreciated that cells employ several DNA repair pathways to take care of distinct types of DNA damage. It is also well known that a cascade of signals namely DNA damage response or DDR is activated in response to DNA damage which comprise cellular responses, such as cell cycle arrest, DNA repair and cell death, if the damage is irreparable. There is also emerging literature suggesting a cross-talk between DNA damage signaling and several signaling networks within a cell. Moreover, cell death players themselves are also well known to engage in processes outside their canonical function of apoptosis. This chapter attempts to build a link between DNA damage, DDR and signaling from the studies mainly conducted in mammals and Drosophila model systems, with a special emphasis on their relevance in overall tissue homeostasis and development.
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Affiliation(s)
- Chaitali Khan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sonia Muliyil
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - B J Rao
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India.
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18
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Verghese S, Su TT. Ionizing radiation induces stem cell-like properties in a caspase-dependent manner in Drosophila. PLoS Genet 2018; 14:e1007659. [PMID: 30462636 PMCID: PMC6248896 DOI: 10.1371/journal.pgen.1007659] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 08/27/2018] [Indexed: 11/18/2022] Open
Abstract
Cancer treatments including ionizing radiation (IR) can induce cancer stem cell-like properties in non-stem cancer cells, an outcome that can interfere with therapeutic success. Yet, we understand little about what consequences of IR induces stem cell like properties and why some cancer cells show this response but not others. In previous studies, we identified a pool of epithelial cells in Drosophila larval wing discs that display IR-induced stem cell-like properties. These cells are resistant to killing by IR and, after radiation damage, change fate and translocate to regenerate parts of the disc that suffered more cell death. Here, we report the identification of two new pools of cells with IR-induced regenerative capability. We addressed how IR exposure results in the induction of stem cell-like behavior, and found a requirement for IR-induced caspase activity and for Zfh2, a transcription factor and an effector in the JAK/STAT pathway. Unexpectedly, the requirement for caspase activity was cell-autonomous within cell populations that display regenerative behavior. We propose a model in which the requirement for caspase activity and Zfh2 can be explained by apoptotic and non-apoptotic functions of caspases in the induction of stem cell-like behavior. Ionizing Radiation (IR), alone or in combination with other therapies, is used to treat an estimated half of all cancer patients. Yet, we understand little about why some tumors cells respond to treatment while others grow back (regenerate). We identified specific pools of cells within a Drosophila organ that are capable of regeneration after damage by IR. We also identified what it is about IR damage that allows these cells to regenerate. These results help us understand how tissues regenerate after IR damage and will aid in designing better therapies that involve radiation.
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Affiliation(s)
- Shilpi Verghese
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States of America
| | - Tin Tin Su
- University of Colorado Comprehensive Cancer Center, Anschutz Medical Campus, Aurora, CO, United States of America
- * E-mail:
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19
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Bayer FE, Zimmermann M, Preiss A, Nagel AC. Overexpression of the Drosophila ATR homologous checkpoint kinase Mei-41 induces a G2/M checkpoint in Drosophila imaginal tissue. Hereditas 2018; 155:27. [PMID: 30202398 PMCID: PMC6125995 DOI: 10.1186/s41065-018-0066-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 08/28/2018] [Indexed: 11/25/2022] Open
Abstract
Background DNA damage generally results in the activation of ATM/ATR kinases and the downstream checkpoint kinases Chk1/Chk2. In Drosophila melanogaster, the ATR homologue meiotic 41 (mei-41) is pivotal to DNA damage repair and cell cycle checkpoint signalling. Although various mei-41 mutant alleles have been analyzed in the past, no gain-of-function allele is yet available. To fill this gap, we have generated transgenic flies allowing temporal and tissue-specific induction of mei-41. Results Overexpression of mei-41 in wing and eye anlagen affects proliferation and a G2/M checkpoint even in the absence of genomic stress. Similar consequences were observed following the overexpression of the downstream kinase Grapes (Grp) but not of Loki (Lok), encoding the respective Drosophila Chk1 and Chk2 homologues, in agreement with their previously reported activities. Moreover, we show that irradiation induced cell cycle arrest was prolonged in the presence of ectopic mei-41 expression. Similar to irradiation stress, mei-41 triggered the occurrence of a slower migrating form of Grp, implying specific phosphorylation of Grp in response to either signal. Using a p53R-GFP biosensor, we further show that overexpression of mei-41 was sufficient to elicit a robust p53 activation in vivo. Conclusion We conclude that overexpression of the Drosophila ATR homologue mei-41 elicits an effectual DNA damage response irrespective of irradiation. Electronic supplementary material The online version of this article (10.1186/s41065-018-0066-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fabienne E Bayer
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
| | - Mirjam Zimmermann
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anette Preiss
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anja C Nagel
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
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20
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Gorelick-Ashkenazi A, Weiss R, Sapozhnikov L, Florentin A, Tarayrah-Ibraheim L, Dweik D, Yacobi-Sharon K, Arama E. Caspases maintain tissue integrity by an apoptosis-independent inhibition of cell migration and invasion. Nat Commun 2018; 9:2806. [PMID: 30022065 PMCID: PMC6052023 DOI: 10.1038/s41467-018-05204-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 05/22/2018] [Indexed: 11/15/2022] Open
Abstract
Maintenance of tissue integrity during development and homeostasis requires the precise coordination of several cell-based processes, including cell death. In animals, the majority of such cell death occurs by apoptosis, a process mediated by caspase proteases. To elucidate the role of caspases in tissue integrity, we investigated the behavior of Drosophila epithelial cells that are severely compromised for caspase activity. We show that these cells acquire migratory and invasive capacities, either within 1–2 days following irradiation or spontaneously during development. Importantly, low levels of effector caspase activity, which are far below the threshold required to induce apoptosis, can potently inhibit this process, as well as a distinct, developmental paradigm of primordial germ cell migration. These findings may have implications for radiation therapy in cancer treatment. Furthermore, given the presence of caspases throughout metazoa, our results could imply that preventing unwanted cell migration constitutes an ancient non-apoptotic function of these proteases. In addition to regulating programmed cell death, caspases also have non-apoptotic roles. Here, the authors show that low level caspase activity prevents cell migration to maintain tissue integrity.
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Affiliation(s)
| | - Ron Weiss
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Lena Sapozhnikov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Anat Florentin
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel.,Department of Cellular Biology, University of Georgia, Athens, GA, 30602-2607, USA
| | | | - Dima Dweik
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Keren Yacobi-Sharon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Eli Arama
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, 76100, Israel.
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21
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Gene-knocked out chimeric antigen receptor (CAR) T cells: Tuning up for the next generation cancer immunotherapy. Cancer Lett 2018; 423:95-104. [DOI: 10.1016/j.canlet.2018.03.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/06/2018] [Accepted: 03/07/2018] [Indexed: 12/15/2022]
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22
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Yoon YJ, Suh MJ, Lee HY, Lee HJ, Choi EH, Moon IS, Song K. Anti-tumor effects of cold atmospheric pressure plasma on vestibular schwannoma demonstrate its feasibility as an intra-operative adjuvant treatment. Free Radic Biol Med 2018; 115:43-56. [PMID: 29138018 DOI: 10.1016/j.freeradbiomed.2017.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 11/07/2017] [Accepted: 11/10/2017] [Indexed: 12/12/2022]
Abstract
Vestibular schwannoma (VS), although a benign intracranial tumor, causes morbidities by brainstem compression. Since chemotherapy is not very effective in most Nf2-negative schwannomas, surgical removal or radiation therapy is required. However, depending on the size and site of the tumor, these approaches may cause loss of auditory or vestibular functions, and severely decrease the post-surgical wellbeing. Here, we examined the feasibility of cold atmospheric pressure plasma (CAP) as an intra-operative adjuvant treatment for VS after surgery. Cell death was efficiently induced in both human HEI-193 and mouse SC4 VS cell lines upon exposure to CAP for seven minutes. Interestingly, both apoptosis and necroptosis were simultaneously induced by CAP treatment, and cell death was not completely inhibited by pan-caspase and receptor-interacting serine/threonine-protein kinase 1 (RIK1) inhibitors. Upon CAP exposure, cell death phenotype was similarly observed in patient-derived primary VS cells and tumor mass. In addition, CAP exposure after the surgical removal of primary tumor efficiently inhibited tumor recurrence in SC4-grafted mouse models. Collectively, these results strongly suggest that CAP should be developed as an efficient adjuvant treatment for VS after surgery to eliminate the possible remnant tumor cells, and to minimize the surgical area in the brain for post-surgical wellbeing.
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Affiliation(s)
- Yeo Jun Yoon
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Michelle J Suh
- Department of Otorhinolaryngology, College of Medicine, Yonsei University, Seoul 03722, Korea
| | - Hyun Young Lee
- Department of Electrical Engineering, Pusan National University, Pusan 46269, Korea
| | - Hae June Lee
- Department of Electrical Engineering, Pusan National University, Pusan 46269, Korea
| | - Eun Ha Choi
- Plasma Bioscience Research Center and Department of Electrical and Biological Physics, Kwangwoon University, Seoul 01897, Korea
| | - In Seok Moon
- Department of Otorhinolaryngology, College of Medicine, Yonsei University, Seoul 03722, Korea.
| | - Kiwon Song
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul 03722, Korea.
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23
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Lu KL, Yamashita YM. Germ cell connectivity enhances cell death in response to DNA damage in the Drosophila testis. eLife 2017; 6:27960. [PMID: 28809158 PMCID: PMC5577909 DOI: 10.7554/elife.27960] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/21/2017] [Indexed: 12/25/2022] Open
Abstract
Two broadly known characteristics of germ cells in many organisms are their development as a ‘cyst’ of interconnected cells and their high sensitivity to DNA damage. Here we provide evidence that in the Drosophila testis, connectivity serves as a mechanism that confers to spermatogonia a high sensitivity to DNA damage. We show that all spermatogonia within a cyst die synchronously even when only a subset of them exhibit detectable DNA damage. Mutants of the fusome, an organelle that is known to facilitate intracyst communication, compromise synchronous spermatogonial death and reduces overall germ cell death. Our data indicate that a death-promoting signal is shared within the cyst, leading to death of the entire cyst. Taken together, we propose that intercellular connectivity supported by the fusome uniquely increases the sensitivity of the germline to DNA damage, thereby protecting the integrity of gamete genomes that are passed on to the next generation.
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Affiliation(s)
- Kevin L Lu
- Life Sciences Institute, University of Michigan, Ann Arbor, United States.,Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, United States.,Medical Scientist Training Program, University of Michigan, Ann Arbor, United States
| | - Yukiko M Yamashita
- Life Sciences Institute, University of Michigan, Ann Arbor, United States.,Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, United States.,Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, United States.,Howard Hughes Medical Institute, University of Michigan, Ann Arbor, United States
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24
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Yim JH, Yun JM, Kim JY, Lee IK, Nam SY, Kim CS. Phosphoprotein profiles of candidate markers for early cellular responses to low-dose γ-radiation in normal human fibroblast cells. JOURNAL OF RADIATION RESEARCH 2017; 58:329-340. [PMID: 28122968 PMCID: PMC5440887 DOI: 10.1093/jrr/rrw126] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/24/2016] [Accepted: 12/09/2016] [Indexed: 05/24/2023]
Abstract
Ionizing radiation causes biological damage that leads to severe health effects. However, the effects and subsequent health implications caused by exposure to low-dose radiation are unclear. The objective of this study was to determine phosphoprotein profiles in normal human fibroblast cell lines in response to low-dose and high-dose γ-radiation. We examined the cellular response in MRC-5 cells 0.5 h after exposure to 0.05 or 2 Gy. Using 1318 antibodies by antibody array, we observed ≥1.3-fold increases in a number of identified phosphoproteins in cells subjected to low-dose (0.05 Gy) and high-dose (2 Gy) radiation, suggesting that both radiation levels stimulate distinct signaling pathways. Low-dose radiation induced nucleic acid-binding transcription factor activity, developmental processes, and multicellular organismal processes. By contrast, high-dose radiation stimulated apoptotic processes, cell adhesion and regulation, and cellular organization and biogenesis. We found that phospho-BTK (Tyr550) and phospho-Gab2 (Tyr643) protein levels at 0.5 h after treatment were higher in cells subjected to low-dose radiation than in cells treated with high-dose radiation. We also determined that the phosphorylation of BTK and Gab2 in response to ionizing radiation was regulated in a dose-dependent manner in MRC-5 and NHDF cells. Our study provides new insights into the biological responses to low-dose γ-radiation and identifies potential candidate markers for monitoring exposure to low-dose ionizing radiation.
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Affiliation(s)
- Ji-Hye Yim
- Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seongnam-si, Gyeonggi-do, 13605, Korea
| | - Jung Mi Yun
- Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seongnam-si, Gyeonggi-do, 13605, Korea
| | - Ji Young Kim
- Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seongnam-si, Gyeonggi-do, 13605, Korea
| | - In Kyung Lee
- Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seongnam-si, Gyeonggi-do, 13605, Korea
| | - Seon Young Nam
- Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seongnam-si, Gyeonggi-do, 13605, Korea
| | - Cha Soon Kim
- Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seongnam-si, Gyeonggi-do, 13605, Korea
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25
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Carroll BL, Pulkoski-Gross MJ, Hannun YA, Obeid LM. CHK1 regulates NF-κB signaling upon DNA damage in p53- deficient cells and associated tumor-derived microvesicles. Oncotarget 2017; 7:18159-70. [PMID: 26921248 PMCID: PMC4951279 DOI: 10.18632/oncotarget.7566] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/23/2016] [Indexed: 12/15/2022] Open
Abstract
The recently discovered CHK1-Suppressed (CS) pathway is activated by inhibition or loss of the checkpoint kinase CHK1, promoting an apoptotic response to DNA damage mediated by caspase-2 in p53-deficient cells. Although functions of the CS-pathway have been investigated biochemically, it remains unclear whether and how CHK1 inhibition can be regulated endogenously and whether this constitutes a key component of the DNA damage response (DDR). Here, we present data that define the first endogenous activation of the CS-pathway whereby, upon DNA damage, wild type p53 acts as an endogenous regulator of CHK1 levels that modulates caspase-2 activation. Moreover, we demonstrate that persistence of CHK1 levels in response to DNA damage in p53-deficient cancer cells, leads to CHK1-mediated activation of NF-κB and induction of NF-κB-regulated genes in cells and in associated tumor-derived microvesicles (TMVs), both of which are abrogated by loss or inhibition of CHK1. These data define a novel role for CHK1 in the DDR pathway as a regulator NF-κB activity. Our data provide evidence that targeting CHK1 in p53-deficient cancers may abrogate NF-κB signaling that is associated with increased cellular survival and chemoresistance.
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Affiliation(s)
- Brittany L Carroll
- Stony Brook Cancer Center and The Department of Medicine, Stony Brook, New York, USA
| | - Michael J Pulkoski-Gross
- Stony Brook Cancer Center and The Department of Medicine, Stony Brook, New York, USA.,Pharmacological Sciences, Stony Brook University, Health Sciences Center, Stony Brook, New York, USA
| | - Yusuf A Hannun
- Stony Brook Cancer Center and The Department of Medicine, Stony Brook, New York, USA
| | - Lina M Obeid
- Stony Brook Cancer Center and The Department of Medicine, Stony Brook, New York, USA.,Northport Veterans Affairs Medical Center, Northport, New York, USA
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26
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Male-killing symbiont damages host's dosage-compensated sex chromosome to induce embryonic apoptosis. Nat Commun 2016; 7:12781. [PMID: 27650264 PMCID: PMC5036004 DOI: 10.1038/ncomms12781] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/01/2016] [Indexed: 12/02/2022] Open
Abstract
Some symbiotic bacteria are capable of interfering with host reproduction in selfish ways. How such bacteria can manipulate host's sex-related mechanisms is of fundamental interest encompassing cell, developmental and evolutionary biology. Here, we uncover the molecular and cellular mechanisms underlying Spiroplasma-induced embryonic male lethality in Drosophila melanogaster. Transcriptomic analysis reveals that many genes related to DNA damage and apoptosis are up-regulated specifically in infected male embryos. Detailed genetic and cytological analyses demonstrate that male-killing Spiroplasma causes DNA damage on the male X chromosome interacting with the male-specific lethal (MSL) complex. The damaged male X chromosome exhibits a chromatin bridge during mitosis, and bridge breakage triggers sex-specific abnormal apoptosis via p53-dependent pathways. Notably, the MSL complex is not only necessary but also sufficient for this cytotoxic process. These results highlight symbiont's sophisticated strategy to target host's sex chromosome and recruit host's molecular cascades toward massive apoptosis in a sex-specific manner. Symbiotic bacteria are able to interfere with host reproduction in ways that are detrimental to the host organism. Here the authors show that Spiroplasma induces DNA damage on the male X chromosome in Drosophila, causing sex-specific apoptosis.
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27
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Drosophila Wnt and STAT Define Apoptosis-Resistant Epithelial Cells for Tissue Regeneration after Irradiation. PLoS Biol 2016; 14:e1002536. [PMID: 27584613 PMCID: PMC5008734 DOI: 10.1371/journal.pbio.1002536] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 07/27/2016] [Indexed: 01/05/2023] Open
Abstract
Drosophila melanogaster larvae irradiated with doses of ionizing radiation (IR) that kill about half of the cells in larval imaginal discs still develop into viable adults. How surviving cells compensate for IR-induced cell death to produce organs of normal size and appearance remains an active area of investigation. We have identified a subpopulation of cells within the continuous epithelium of Drosophila larval wing discs that shows intrinsic resistance to IR- and drug-induced apoptosis. These cells reside in domains of high Wingless (Wg, Drosophila Wnt-1) and STAT92E (sole Drosophila signal transducer and activator of transcription [STAT] homolog) activity and would normally form the hinge in the adult fly. Resistance to IR-induced apoptosis requires STAT and Wg and is mediated by transcriptional repression of the pro-apoptotic gene reaper. Lineage tracing experiments show that, following irradiation, apoptosis-resistant cells lose their identity and translocate to areas of the wing disc that suffered abundant cell death. Our findings provide a new paradigm for regeneration in which it is unnecessary to invoke special damage-resistant cell types such as stem cells. Instead, differences in gene expression within a population of genetically identical epithelial cells can create a subpopulation with greater resistance, which, following damage, survive, alter their fate, and help regenerate the tissue. After widespread radiation damage in the developing fruit fly, organs are formed by regeneration from an apoptosis-resistant subpopulation of cells marked by high levels of Wingless and STAT. Like other insects, Drosophila larvae have epithelial structures called imaginal discs that will give rise to most of the external adult structures, such as wings, limbs, or antennae; these organ precursors are formed by a single layer of epithelial cells that folds into a sac. Imaginal discs manage to regenerate efficiently if they are damaged. Previous studies have shown that dying cells produce signals that activate cell proliferation of some of their neighbors, allowing them to regenerate the disc and thereby enabling the flies to develop into normal adults. But a dedicated stem cell population that contributes to regeneration, if any, remained to be identified. Here, we report the identification of a subpopulation of cells in wing imaginal discs that is more resistant to the cytotoxic effects of radiation and drugs. We show that the protection of these cells depends on two signaling pathways—Wingless and STAT—that are conserved in humans. Following tissue damage by radiation, we observe that protected cells change their location and their identity, allowing them to fill in for dead cells in other parts of the same organ precursor. In sum, this work identified ways in which a subset of cells in Drosophila imaginal wing discs is preserved through radiation exposure so that they could participate in regeneration of the organ after radiation damage. We also discuss how this situation may resemble human cancers.
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28
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Qi S, Calvi BR. Different cell cycle modifications repress apoptosis at different steps independent of developmental signaling in Drosophila. Mol Biol Cell 2016; 27:1885-97. [PMID: 27075174 PMCID: PMC4907722 DOI: 10.1091/mbc.e16-03-0139] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/08/2016] [Indexed: 11/11/2022] Open
Abstract
Genetic manipulations of the cell cycle repress apoptosis independent of developmental signaling. The findings have broader relevance to understanding the coordination of cell proliferation and apoptosis in development and disease. Apoptotic cell death is important for the normal development of a variety of organisms. Apoptosis is also a response to DNA damage and an important barrier to oncogenesis. The apoptotic response to DNA damage is dampened in specific cell types during development. Developmental signaling pathways can repress apoptosis, and reduced cell proliferation also correlates with a lower apoptotic response. However, because developmental signaling regulates both cell proliferation and apoptosis, the relative contribution of cell division to the apoptotic response has been hard to discern in vivo. Here we use Drosophila oogenesis as an in vivo model system to determine the extent to which cell proliferation influences the apoptotic response to DNA damage. We find that different types of cell cycle modifications are sufficient to repress the apoptotic response to ionizing radiation independent of developmental signaling. The step(s) at which the apoptosis pathway was repressed depended on the type of cell cycle modification—either upstream or downstream of expression of the p53-regulated proapoptotic genes. Our findings have important implications for understanding the coordination of cell proliferation with the apoptotic response in development and disease, including cancer and the tissue-specific responses to radiation therapy.
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Affiliation(s)
- Suozhi Qi
- Department of Biology, Indiana University, Bloomington, IN 47405
| | - Brian R Calvi
- Department of Biology, Indiana University, Bloomington, IN 47405
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Abstract
Drosophila has served as a particularly attractive model to study cell death due to the vast array of tools for genetic manipulation under defined spatial and temporal conditions in vivo as well as in cultured cells. These genetic methods have been well supplemented by enzymatic assays and a panel of antibodies recognizing cell death markers. This chapter discusses reporters, mutants, and assays used by various laboratories to study cell death in the context of development and in response to external insults.
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Affiliation(s)
- Deepika Vasudevan
- Department of Cell Biology, New York University School of Medicine, 550 First Ave., New York, NY, 10016, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, 550 First Ave., New York, NY, 10016, USA.
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Zhang B, Rotelli M, Dixon M, Calvi BR. The function of Drosophila p53 isoforms in apoptosis. Cell Death Differ 2015; 22:2058-67. [PMID: 25882045 DOI: 10.1038/cdd.2015.40] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 12/20/2022] Open
Abstract
The p53 protein is a major mediator of the cellular response to genotoxic stress and is a crucial suppressor of tumor formation. In a variety of organisms, p53 and its paralogs, p63 and p73, each encode multiple protein isoforms through alternative splicing, promoters, and translation start sites. The function of these isoforms in development and disease are still being defined. Here, we evaluate the apoptotic potential of multiple isoforms of the single p53 gene in the genetic model Drosophila melanogaster. Most previous studies have focused on the p53A isoform, but it has been recently shown that a larger p53B isoform can induce apoptosis when overexpressed. It has remained unclear, however, whether one or both isoforms are required for the apoptotic response to genotoxic stress. We show that p53B is a much more potent inducer of apoptosis than p53A when overexpressed. Overexpression of two newly identified short isoforms perturbed development and inhibited the apoptotic response to ionizing radiation. Analysis of physiological protein expression indicated that p53A is the most abundant isoform, and that both p53A and p53B can form a complex and co-localize to sub-nuclear compartments. In contrast to the overexpression results, new isoform-specific loss-of-function mutants indicated that it is the shorter p53A isoform, not full-length p53B, that is the primary mediator of pro-apoptotic gene transcription and apoptosis after ionizing radiation. Together, our data show that it is the shorter p53A isoform that mediates the apoptotic response to DNA damage, and further suggest that p53B and shorter isoforms have specialized functions.
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Affiliation(s)
- B Zhang
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - M Rotelli
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - M Dixon
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - B R Calvi
- Department of Biology, Indiana University, Bloomington, IN, USA
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31
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Responses of solid tumor cells in DMEM to reactive oxygen species generated by non-thermal plasma and chemically induced ROS systems. Sci Rep 2015; 5:8587. [PMID: 25715710 PMCID: PMC4341198 DOI: 10.1038/srep08587] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/27/2015] [Indexed: 02/08/2023] Open
Abstract
In this study, we assessed the role of different reactive oxygen species (ROS) generated by soft jet plasma and chemical-induced ROS systems with regard to cell death in T98G, A549, HEK293 and MRC5 cell lines. For a comparison with plasma, we generated superoxide anion (O2−), hydroxyl radical (HO·), and hydrogen peroxide (H2O2) with chemicals inside an in vitro cell culture. Our data revealed that plasma decreased the viability and intracellular ATP values of cells and increased the apoptotic population via a caspase activation mechanism. Plasma altered the mitochondrial membrane potential and eventually up-regulated the mRNA expression levels of BAX, BAK1 and H2AX gene but simultaneously down-regulated the levels of Bcl-2 in solid tumor cells. Moreover, a western blot analysis confirmed that plasma also altered phosphorylated ERK1/2/MAPK protein levels. At the same time, using ROS scavengers with plasma, we observed that scavengers of HO· (mannitol) and H2O2 (catalase and sodium pyruvate) attenuated the activity of plasma on cells to a large extent. In contrast, radicals generated by specific chemical systems enhanced cell death drastically in cancer as well as normal cell lines in a dose-dependent fashion but not specific with regard to the cell type as compared to plasma.
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Zhang C, Casas-Tintó S, Li G, Lin N, Chung M, Moreno E, Moberg KH, Zhou L. An intergenic regulatory region mediates Drosophila Myc-induced apoptosis and blocks tissue hyperplasia. Oncogene 2014; 34:2385-97. [PMID: 24931167 PMCID: PMC4268096 DOI: 10.1038/onc.2014.160] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 12/31/2022]
Abstract
Induction of cell-autonomous apoptosis following oncogene-induced overproliferation is a major tumor-suppressive mechanism in vertebrates. However, the detailed mechanism mediating this process remains enigmatic. In this study, we demonstrate that dMyc-induced cell-autonomous apoptosis in the fruit fly Drosophila melanogaster relies on an intergenic sequence termed the IRER (irradiation-responsive enhancer region). The IRER mediates the expression of surrounding proapoptotic genes, and we use an in vivo reporter of the IRER chromatin state to gather evidence that epigenetic control of DNA accessibility within the IRER is an important determinant of the strength of this response to excess dMyc. In a previous work, we showed that the IRER also mediates P53-dependent induction of proapoptotic genes following DNA damage, and the chromatin conformation within IRER is regulated by polycomb group-mediated histone modifications. dMyc-induced apoptosis and the P53-mediated DNA damage response thus overlap in a requirement for the IRER. The epigenetic mechanisms controlling IRER accessibility appear to set thresholds for the P53- and dMyc-induced expression of apoptotic genes in vivo and may have a profound impact on cellular sensitivity to oncogene-induced stress.
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Affiliation(s)
- C Zhang
- 1] Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA [2] Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - S Casas-Tintó
- Cajal Institute, Spanish Research Council (CSIC), Madrid, Spain
| | - G Li
- 1] Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA [2] UF Genetics Institute, University of Florida, Gainesville, FL, USA
| | - N Lin
- Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA
| | - M Chung
- Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA
| | - E Moreno
- Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - K H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - L Zhou
- 1] Department of Molecular Genetics and Microbiology and UF Shands Cancer Center, University of Florida, Gainesville, FL, USA [2] UF Genetics Institute, University of Florida, Gainesville, FL, USA
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Lin R, Angelin A, Da Settimo F, Martini C, Taliani S, Zhu S, Wallace DC. Genetic analysis of dTSPO, an outer mitochondrial membrane protein, reveals its functions in apoptosis, longevity, and Ab42-induced neurodegeneration. Aging Cell 2014; 13:507-18. [PMID: 24977274 PMCID: PMC4076708 DOI: 10.1111/acel.12200] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The outer mitochondrial membrane (OMM) protein, the translocator protein 18 kDa (TSPO), formerly named the peripheral benzodiazepine receptor (PBR), has been proposed to participate in the pathogenesis of neurodegenerative diseases. To clarify the TSPO function, we identified the Drosophila homolog, CG2789/dTSPO, and studied the effects of its inactivation by P-element insertion, RNAi knockdown, and inhibition by ligands (PK11195, Ro5-4864). Inhibition of dTSPO inhibited wing disk apoptosis in response to γ-irradiation or H2O2 exposure, as well as extended male fly lifespan and inhibited Aβ42-induced neurodegeneration in association with decreased caspase activation. Therefore, dTSPO is an essential mediator of apoptosis in Drosophila and plays a central role in controlling longevity and neurodegenerative disease, making it a promising drug target.
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Affiliation(s)
- Ran Lin
- Department of Physiology and Pathophysiology School of Basic Medical Sciences Health Science Center Peking University Beijing 100191China
- Center for Mitochondrial and Epigenomic Medicine Children's Hospital of Philadelphia Research Institute Philadelphia PA 19104USA
| | - Alessia Angelin
- Center for Mitochondrial and Epigenomic Medicine Children's Hospital of Philadelphia Research Institute Philadelphia PA 19104USA
| | | | - Claudia Martini
- Dipartimento di Farmacia Università di Pisa via Bonanno 656126Pisa Italy
| | - Sabrina Taliani
- Dipartimento di Farmacia Università di Pisa via Bonanno 656126Pisa Italy
| | - Shigong Zhu
- Department of Physiology and Pathophysiology School of Basic Medical Sciences Health Science Center Peking University Beijing 100191China
| | - Douglas C. Wallace
- Center for Mitochondrial and Epigenomic Medicine Children's Hospital of Philadelphia Research Institute Philadelphia PA 19104USA
- Department of Pathology and Laboratory Medicine Perelman School of Medicine University of Pennsylvania Philadelphia PA 19104USA
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34
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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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Dying cells protect survivors from radiation-induced cell death in Drosophila. PLoS Genet 2014; 10:e1004220. [PMID: 24675716 PMCID: PMC3967929 DOI: 10.1371/journal.pgen.1004220] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 01/20/2014] [Indexed: 12/19/2022] Open
Abstract
We report a phenomenon wherein induction of cell death by a variety of means in wing imaginal discs of Drosophila larvae resulted in the activation of an anti-apoptotic microRNA, bantam. Cells in the vicinity of dying cells also become harder to kill by ionizing radiation (IR)-induced apoptosis. Both ban activation and increased protection from IR required receptor tyrosine kinase Tie, which we identified in a genetic screen for modifiers of ban. tie mutants were hypersensitive to radiation, and radiation sensitivity of tie mutants was rescued by increased ban gene dosage. We propose that dying cells activate ban in surviving cells through Tie to make the latter cells harder to kill, thereby preserving tissues and ensuring organism survival. The protective effect we report differs from classical radiation bystander effect in which neighbors of irradiated cells become more prone to death. The protective effect also differs from the previously described effect of dying cells that results in proliferation of nearby cells in Drosophila larval discs. If conserved in mammals, a phenomenon in which dying cells make the rest harder to kill by IR could have implications for treatments that involve the sequential use of cytotoxic agents and radiation therapy. In multicellular organisms where cells exist in the context of other cells, the behavior of one affects the others. The consequences of such interactions include not just cell fate choices but also life and death decisions. In the wing primordia of Drosophila melanogaster larvae, dying cells release mitogenic signals that stimulate the neighbors to proliferate. Such an effect is proposed to compensate for cell loss and help regenerate the tissue. We report here that, in the same experimental system, dying cells activate a pro-survival microRNA, bantam, in surviving cells. This results in increased protection from the killing effect of ionizing radiation (IR). Activation of ban requires tie, which encodes a receptor tyrosine kinase. tie and ban mutant larvae are hypersensitive to killing by IR, suggesting that the responses described here are important for organismal survival following radiation exposure.
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Shim HJ, Lee EM, Nguyen LD, Shim J, Song YH. High-dose irradiation induces cell cycle arrest, apoptosis, and developmental defects during Drosophila oogenesis. PLoS One 2014; 9:e89009. [PMID: 24551207 PMCID: PMC3923870 DOI: 10.1371/journal.pone.0089009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 01/14/2014] [Indexed: 11/18/2022] Open
Abstract
Ionizing radiation (IR) treatment induces a DNA damage response, including cell cycle arrest, DNA repair, and apoptosis in metazoan somatic cells. Because little has been reported in germline cells, we performed a temporal analysis of the DNA damage response utilizing Drosophila oogenesis as a model system. Oogenesis in the adult Drosophila female begins with the generation of 16-cell cyst by four mitotic divisions of a cystoblast derived from the germline stem cells. We found that high-dose irradiation induced S and G2 arrests in these mitotically dividing germline cells in a grp/Chk1- and mnk/Chk2-dependent manner. However, the upstream kinase mei-41, Drosophila ATR ortholog, was required for the S-phase checkpoint but not for the G2 arrest. As in somatic cells, mnk/Chk2 and dp53 were required for the major cell death observed in early oogenesis when oocyte selection and meiotic recombination occurs. Similar to the unscheduled DNA double-strand breaks (DSBs) generated from defective repair during meiotic recombination, IR-induced DSBs produced developmental defects affecting the spherical morphology of meiotic chromosomes and dorsal-ventral patterning. Moreover, various morphological abnormalities in the ovary were detected after irradiation. Most of the IR-induced defects observed in oogenesis were reversible and were restored between 24 and 96 h after irradiation. These defects in oogenesis severely reduced daily egg production and the hatch rate of the embryos of irradiated female. In summary, irradiated germline cells induced DSBs, cell cycle arrest, apoptosis, and developmental defects resulting in reduction of egg production and defective embryogenesis.
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Affiliation(s)
- Hee Jin Shim
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Korea
| | - Eun-Mi Lee
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Korea
| | - Long Duy Nguyen
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Korea
| | - Jaekyung Shim
- Department of Molecular Biology, Sejong University, Seoul, Korea
| | - Young-Han Song
- Ilsong Institute of Life Science, Hallym University, Anyang, Gyeonggi-do, Korea
- * E-mail:
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Hassel C, Zhang B, Dixon M, Calvi BR. Induction of endocycles represses apoptosis independently of differentiation and predisposes cells to genome instability. Development 2013; 141:112-23. [PMID: 24284207 DOI: 10.1242/dev.098871] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The endocycle is a common developmental cell cycle variation wherein cells become polyploid through repeated genome duplication without mitosis. We previously showed that Drosophila endocycling cells repress the apoptotic cell death response to genotoxic stress. Here, we investigate whether it is differentiation or endocycle remodeling that promotes apoptotic repression. We find that when nurse and follicle cells switch into endocycles during oogenesis they repress the apoptotic response to DNA damage caused by ionizing radiation, and that this repression has been conserved in the genus Drosophila over 40 million years of evolution. Follicle cells defective for Notch signaling failed to switch into endocycles or differentiate and remained apoptotic competent. However, genetic ablation of mitosis by knockdown of Cyclin A or overexpression of fzr/Cdh1 induced follicle cell endocycles and repressed apoptosis independently of Notch signaling and differentiation. Cells recovering from these induced endocycles regained apoptotic competence, showing that repression is reversible. Recovery from fzr/Cdh1 overexpression also resulted in an error-prone mitosis with amplified centrosomes and high levels of chromosome loss and fragmentation. Our results reveal an unanticipated link between endocycles and the repression of apoptosis, with broader implications for how endocycles may contribute to genome instability and oncogenesis.
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Affiliation(s)
- Christiane Hassel
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Fereres S, Simón R, Busturia A. A novel dRYBP–SCF complex functions to inhibit apoptosis in Drosophila. Apoptosis 2013; 18:1500-12. [DOI: 10.1007/s10495-013-0897-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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39
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Halacli SO, Canpinar H, Cimen E, Sunguroglu A. Effects of gamma irradiation on cell cycle, apoptosis and telomerase activity in p53 wild-type and deficient HCT116 colon cancer cell lines. Oncol Lett 2013; 6:807-810. [PMID: 24137415 PMCID: PMC3789084 DOI: 10.3892/ol.2013.1441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 06/19/2013] [Indexed: 11/15/2022] Open
Abstract
Radiotherapy serves as adjunctive treatment to chemotherapy and surgical resection of colorectal cancer. However, the cellular response to irradiation varies depending on the expression of tumor suppressor p53, which plays a significant role in the regulation of cell cycle arrest, apoptosis and telomerase activity in various cancers. The present study aimed to investigate cell cycle arrest, apoptosis and telomerase activity with respect to p53 expression in p53 wild-type (+/+) and deficient (−/−) HCT116 colon cancer cell lines following 5 Gy γ-irradiation. Cell cycle arrest and apoptosis were evaluated using flow cytometry. The telomerase activity was measured using a TRAP (telomerase repeat amplification protocol) assay. Following treatment with irradiation, G1/S cell cycle arrest occurred in the p53+/+ cells, whereas the p53−/− cells accumulated in the G2 phase. No differences were observed in the apoptotic ratios between the two cell lines following irradiation. Decreased telomerase activity was observed in the p53+/+ cells, whereas telomerase activity was increased in the p53−/− cells. The results showed that while telomerase activity and G1 cell cycle arrest were regulated depending on the p53 status, G2 arrest and the apoptotic response were promoted via a p53-independent pathway.
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Affiliation(s)
- Sevil Oskay Halacli
- Pediatric Immunology Unit, Institute of Children's Health, Hacettepe University, Sihhiye, Ankara 06100, Turkey
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40
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James A, Cindass R, Mayer D, Terhoeve S, Mumphrey C, DiMario P. Nucleolar stress in Drosophila melanogaster: RNAi-mediated depletion of Nopp140. Nucleus 2013; 4:123-33. [PMID: 23412656 DOI: 10.4161/nucl.23944] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Nucleolar stress results when ribosome biogenesis is disrupted. An excellent example is the human Treacher Collins syndrome in which the loss of the nucleolar chaperone, Treacle, leads to p53-dependent apoptosis in embryonic neural crest cells and ultimately to craniofacial birth defects. Here, we show that depletion of the related nucleolar phosphoprotein, Nopp140, in Drosophila melanogaster led to nucleolar stress and eventual lethality when multiple tissues were depleted of Nopp140. We used TEM, immuno-blot analysis and metabolic protein labeling to show the loss of ribosomes. Targeted loss of Nopp140 in larval wing discs caused Caspase-dependent apoptosis which eventually led to defects in the adult wings. These defects were not rescued by a p53 gene deletion, as the craniofacial defects were in the murine model of TCS, thus suggesting that apoptosis caused by nucleolar stress in Drosophila is induced by a p53-independent mechanism. Loss of Nopp140 in larval polyploid midgut cells induced premature autophagy as marked by the accumulation of mCherry-ATG8a into autophagic vesicles. We also found elevated phenoloxidase A3 levels in whole larval lysates and within the hemolymph of Nopp140-depleted larvae vs. hemolymph from parental genotype larvae. Phenoloxidase A3 enrichment was coincident with the appearance of melanotic tumors in the Nopp140-depleted larvae. The occurrence of apoptosis, autophagy and phenoloxidase A3 release to the hemolymph upon nucleolar stress correlated well with the demonstrated activation of Jun N-terminal kinase (JNK) in Nopp140-depleted larvae. We propose that JNK is a central stress response effector that is activated by nucleolar stress in Drosophila larvae.
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Affiliation(s)
- Allison James
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
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41
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Baculoviruses modulate a proapoptotic DNA damage response to promote virus multiplication. J Virol 2012; 86:13542-53. [PMID: 23035220 DOI: 10.1128/jvi.02246-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) initiates apoptosis in diverse insects through events triggered by virus DNA (vDNA) replication. To define the proapoptotic pathway and its role in antivirus defense, we investigated the link between the host's DNA damage response (DDR) and apoptosis. We report here that AcMNPV elicits a DDR in the model insect Drosophila melanogaster. Replication of vDNA activated DDR kinases, as evidenced by ATM-driven phosphorylation of the Drosophila histone H2AX homolog (H2Av), a critical regulator of the DDR. Ablation or inhibition of ATM repressed H2Av phosphorylation and blocked virus-induced apoptosis. The DDR kinase inhibitors caffeine and KU55933 also prevented virus-induced apoptosis in cells derived from the permissive AcMNPV host, Spodoptera frugiperda. This block occurred at a step upstream of virus-mediated depletion of the cellular inhibitor-of-apoptosis protein, an event that initiates apoptosis in Spodoptera and Drosophila. Thus, the DDR is a conserved, proapoptotic response to baculovirus infection. DDR inhibition also repressed vDNA replication and reduced virus yields 100,000-fold, demonstrating that the DDR contributes to virus production, despite its recognized antivirus role. In contrast to virus-induced phosphorylation of Drosophila H2Av, AcMNPV blocked phosphorylation of the Spodoptera H2AX homolog (SfH2AX). Remarkably, AcMNPV also suppressed SfH2AX phosphorylation following pharmacologically induced DNA damage. These findings indicate that AcMNPV alters canonical DDR signaling in permissive cells. We conclude that AcMNPV triggers a proapoptotic DDR that is subsequently modified, presumably to stimulate vDNA replication. Thus, manipulation of the DDR to facilitate multiplication is an evolutionarily conserved strategy among DNA viruses of insects and mammals.
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The tumor suppressor Caliban regulates DNA damage-induced apoptosis through p53-dependent and -independent activity. Oncogene 2012; 32:3857-66. [PMID: 22964637 DOI: 10.1038/onc.2012.395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 06/04/2012] [Accepted: 07/20/2012] [Indexed: 12/18/2022]
Abstract
We previously identified Caliban (Clbn) as the Drosophila homolog of human Serologically defined colon cancer antigen 1 gene and demonstrated that it could function as a tumor suppressor in human non-small-cell lung cancer (NSCLC) cells, although its mode of action was unknown. Herein, we identify roles for Clbn in DNA damage response. We generate clbn knockout flies using homologous recombination and demonstrate that they have a heightened sensitivity to irradiation. We show that normal Clbn function facilitates both p53-dependent and -independent DNA damage-induced apoptosis. Clbn coordinates different apoptosis pathways, showing a two-stage upregulation following DNA damage. Clbn has proapoptotic functions, working with both caspase and the proapoptotic gene Hid. Finally, ecotopic expression of clbn(+) in NSCLC cells suppresses tumor formation in athymic nude mice. We conclude that Caliban is a regulator of DNA damage-induced apoptosis, functioning as a tumor suppressor in both p53-dependent and -independent pathways.
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Checkpoint kinase 2 (Chk2) inhibits the activity of the Cdc45/MCM2-7/GINS (CMG) replicative helicase complex. Proc Natl Acad Sci U S A 2012; 109:13163-70. [PMID: 22853956 DOI: 10.1073/pnas.1211525109] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The replication of eukaryote chromosomes slows down when DNA is damaged and the proteins that work at the fork (the replisome) are known targets for the signaling pathways that mediate such responses critical for accurate genomic inheritance. However, the molecular mechanisms and details of how this response is mediated are poorly understood. In this report we show that the activity of replisome helicase, the Cdc45/MCM2-7/GINS (CMG) complex, can be inhibited by protein phosphorylation. Recombinant Drosophila melanogaster CMG can be stimulated by treatment with phosphatase whereas Chk2 but not Chk1 interferes with the helicase activity in vitro. The targets for Chk2 phosphorylation have been identified and reside in MCM subunits 3 and 4 and in the GINS protein Psf2. Interference requires a combination of modifications and we suggest that the formation of negative charges might create a surface on the helicase to allosterically affect its function. The treatment of developing fly embryos with ionizing radiation leads to hyperphosphorylation of Psf2 subunit in the active helicase complex. Taken together these data suggest that the direct modification of the CMG helicase by Chk2 is an important nexus for response to DNA damage.
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Liu W, Jiang F, Bi X, Zhang YQ. Drosophila FMRP participates in the DNA damage response by regulating G2/M cell cycle checkpoint and apoptosis. Hum Mol Genet 2012; 21:4655-68. [PMID: 22843500 DOI: 10.1093/hmg/dds307] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Fragile X syndrome, the most common form of inherited mental retardation, is caused by the loss of the fragile X mental retardation protein (FMRP). FMRP is a ubiquitously expressed, multi-domain RNA-binding protein, but its in vivo function remains poorly understood. Recent studies have shown that FMRP participates in cell cycle control during development. Here, we used Drosophila mutants to test if FMRP plays a role in DNA damage response under genotoxic stress. We found significantly fewer dfmr1 mutants survived to adulthood than wild-types following irradiation or exposure to chemical mutagens, demonstrating that the loss of drosophila FMRP (dFMRP) results in hypersensitivity to genotoxic stress. Genotoxic stress significantly reduced mitotic cells in wild-type brains, indicating the activation of a DNA damage-induced G2/M checkpoint, while mitosis was only moderately suppressed in dfmr1 mutants. Elevated expression of cyclin B, a protein critical for the G2 to M transition, was observed in the larval brains of dfmr1 mutants. CycB mRNA transcripts were enriched in the dFMRP-containing complex, suggesting that dFMRP regulates DNA damage-induced G2/M checkpoint by repressing CycB mRNA translation. Reducing CycB dose by half in dfmr1 mutants rescued the defective G2/M checkpoint and reversed hypersensitivity to genotoxic stress. In addition, dfmr1 mutants exhibited more DNA breaks and elevated p53-dependent apoptosis following irradiation. Moreover, a loss-of-heterozygosity assay showed decreased irradiation-induced genome stability in dfmr1 mutants. Thus, dFMRP maintains genome stability under genotoxic stress and regulates the G2/M DNA damage checkpoint by suppressing CycB expression.
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Affiliation(s)
- Wei Liu
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
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van Bergeijk P, Heimiller J, Uyetake L, Su TT. Genome-wide expression analysis identifies a modulator of ionizing radiation-induced p53-independent apoptosis in Drosophila melanogaster. PLoS One 2012; 7:e36539. [PMID: 22666323 PMCID: PMC3362589 DOI: 10.1371/journal.pone.0036539] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/09/2012] [Indexed: 12/20/2022] Open
Abstract
Tumor suppressor p53 plays a key role in DNA damage responses in metazoa, yet more than half of human tumors show p53 deficiencies. Therefore, understanding how therapeutic genotoxins such as ionizing radiation (IR) can elicit DNA damage responses in a p53-independent manner is of clinical importance. Drosophila has been a good model to study the effects of IR because DNA damage responses as well as underlying genes are conserved in this model, and because streamlined gene families make loss-of-function analyses feasible. Indeed, Drosophila is the only genetically tractable model for IR-induced, p53-independent apoptosis and for tissue regeneration and homeostasis after radiation damage. While these phenomenon occur only in the larvae, all genome-wide gene expression analyses after irradiation to date have been in embryos. We report here the first analysis of IR-induced, genome-wide gene expression changes in wild type and p53 mutant Drosophila larvae. Key data from microarrays were confirmed by quantitative RT-PCR. The results solidify the central role of p53 in IR-induced transcriptome changes, but also show that nearly all changes are made of both p53-dependent and p53-independent components. p53 is found to be necessary not just for the induction of but also for the repression of transcript levels for many genes in response to IR. Furthermore, Functional analysis of one of the top-changing genes, EF1a-100E, implicates it in repression of IR-induced p53-independent apoptosis. These and other results support the emerging notion that there is not a single dominant mechanism but that both positive and negative inputs collaborate to induce p53-independent apoptosis in response to IR in Drosophila larvae.
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Affiliation(s)
- Petra van Bergeijk
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Joseph Heimiller
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Lyle Uyetake
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
- * E-mail:
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Gowda PS, Zhou F, Chadwell LV, McEwen DG. p53 binding prevents phosphatase-mediated inactivation of diphosphorylated c-Jun N-terminal kinase. J Biol Chem 2012; 287:17554-17567. [PMID: 22467874 DOI: 10.1074/jbc.m111.319277] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
c-Jun N-terminal kinase (JNK) is a serine/threonine phosphotransferase whose sustained activation in response to genotoxic stress promotes apoptosis. In Drosophila, the normally rapid JNK-dependent apoptotic response to genotoxic stress is significantly delayed in Dmp53 (Drosophila p53) mutants. Likewise, the extent of JNK activity after UV irradiation is dependent on p53 in murine embryonic fibroblasts with loss of p53 resulting in diminished JNK activity. Together, these results suggest that p53 potentiates the JNK-dependent response to genotoxic stress; however, the mechanism whereby p53 stimulates JNK activity remains undefined. Here, we demonstrate that both Drosophila and human p53 can directly stimulate JNK activity independently of p53-dependent gene transcription. Furthermore, we demonstrate that both the Drosophila and human p53 orthologs form a physical complex with diphosphorylated JNK ((DP)JNK) both in vivo and in vitro, suggesting that the interaction is evolutionarily conserved. Focusing on human p53, we demonstrate that the interaction maps to the DNA binding domain (hp53(DBD)). Intriguingly, binding of p53(DBD) alone to (DP)JNK prevented its inactivation by MAPK phosphatase (MKP)-5; however, JNK was still able to phosphorylate c-Jun while in a complex with the p53(DBD). Apparent dissociation constants for the p53(DBD)·(DP)JNK (274 ± 14 nm) and MKP-5·(DP)JNK (55 ± 8 nm) complexes were established; however, binding of MKP-5 and p53 to JNK was not mutually exclusive. Together, these results suggest that stress-dependent increases in p53 levels potentiate JNK activation by preventing its rapid dephosphorylation by MKPs and that the simultaneous activation of p53 and JNK may constitute a "fail-safe" switch for the JNK-dependent apoptotic response.
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Affiliation(s)
- Pramod S Gowda
- Departments of Biochemistry and The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Fuchun Zhou
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center, San Antonio, Texas 78229; Department of Pediatrics and The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Linda V Chadwell
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center, San Antonio, Texas 78229
| | - Donald G McEwen
- Departments of Biochemistry and The University of Texas Health Science Center, San Antonio, Texas 78229; Greehey Children's Cancer Research Institute, The University of Texas Health Science Center, San Antonio, Texas 78229.
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Pyun J, Kang S, Hwang H, Oh Y, Kang S, Lim Y, Choo O, Kim C. Epicatechin inhibits radiation-induced auditory cell death by suppression of reactive oxygen species generation. Neuroscience 2011; 199:410-20. [DOI: 10.1016/j.neuroscience.2011.09.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 09/03/2011] [Accepted: 09/07/2011] [Indexed: 10/17/2022]
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Wells BS, Johnston LA. Maintenance of imaginal disc plasticity and regenerative potential in Drosophila by p53. Dev Biol 2011; 361:263-76. [PMID: 22036477 DOI: 10.1016/j.ydbio.2011.10.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 09/14/2011] [Accepted: 10/08/2011] [Indexed: 10/16/2022]
Abstract
Following irradiation (IR), the DNA damage response (DDR) activates p53, which triggers death of cells in which repair cannot be completed. Lost tissue is then replaced and re-patterned through regeneration. We have examined the role of p53 in co-regulation of the DDR and tissue regeneration following IR damage in Drosophila. We find that after IR, p53 is required for imaginal disc cells to repair DNA, and in its absence the damage marker, γ-H2AX is persistently expressed. p53 is also required for the compensatory proliferation and re-patterning of the damaged discs, and our results indicate that cell death is not required to trigger these processes. We identify an IR-induced delay in developmental patterning in wing discs that accompanies an animal-wide delay of the juvenile-adult transition, and demonstrate that both of these delays require p53. In p53 mutants, the lack of developmental delays and of damage resolution leads to anueploidy and tissue defects, and ultimately to morphological abnormalities and adult inviability. We propose that p53 maintains plasticity of imaginal discs by co-regulating the maintenance of genome integrity and disc regeneration, and coordinating these processes with the physiology of the animal. These findings place p53 in a role as master coordinator of DNA and tissue repair following IR.
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Affiliation(s)
- Brent S Wells
- Department of Genetics & Development, Columbia University Medical Center, New York, NY 10032, USA
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Su TT. Safeguarding genetic information in Drosophila. Chromosoma 2011; 120:547-55. [PMID: 21927823 DOI: 10.1007/s00412-011-0342-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/24/2011] [Accepted: 08/26/2011] [Indexed: 12/11/2022]
Abstract
Eukaryotic cells employ a plethora of conserved proteins and mechanisms to ensure genome integrity. In metazoa, these mechanisms must operate in the context of organism development. This mini-review highlights two emerging features of DNA damage responses in Drosophila: a crosstalk between DNA damage responses and components of the spindle assembly checkpoint, and increasing evidence for the effect of DNA damage on the developmental program at multiple points during the Drosophila life cycle.
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Affiliation(s)
- Tin Tin Su
- MCD Biology, University of Colorado, Boulder, USA.
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Baculovirus infection induces a DNA damage response that is required for efficient viral replication. J Virol 2011; 85:12547-56. [PMID: 21917957 DOI: 10.1128/jvi.05766-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several mammalian viruses have been shown to induce a cellular DNA damage response during replication, and in some cases, this response is required for optimal virus replication. However, nothing is known about whether a DNA damage response is stimulated by DNA viruses in invertebrates. Cell cycle arrest and apoptosis are two of the downstream effects of the DNA damage response, and both are stimulated by baculovirus infection, suggesting a possible relationship between baculoviruses and the DNA damage response. In the study described in this report, we found that replication of the baculovirus Autographa californica M nucleopolyhedrovirus (AcMNPV) in the cell line Sf9, derived from the lepidopteran insect Spodoptera frugiperda, stimulated a DNA damage response, as indicated by an increased abundance of the S. frugiperda P53 protein (SfP53) and phosphorylation of the histone variant protein H2AX. Stimulation of the DNA damage response was dependent on viral DNA replication. Inhibition of the DNA damage response prevented both the increase in SfP53 accumulation and H2AX phosphorylation and also caused a 10- to 100-fold reduction in virus production, along with decreased viral DNA replication and late gene expression. However, silencing of Sfp53 expression by RNA interference did not significantly affect AcMNPV replication or induction of apoptosis by a mutant of AcMNPV lacking the antiapoptotic gene p35, indicating that these processes are not dependent on SfP53 in Sf9 cells.
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