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Vicars H, Karg T, Mills A, Sullivan W. Acentric chromosome congression and alignment on the metaphase plate via kinetochore-independent forces in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.14.567057. [PMID: 38798431 PMCID: PMC11118298 DOI: 10.1101/2023.11.14.567057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Chromosome congression and alignment on the metaphase plate involves lateral and microtubule plus-end interactions with the kinetochore. Here we take advantage of our ability to efficiently generate a GFP-marked acentric X chromosome fragment in Drosophila neuroblasts to identify forces acting on chromosome arms that drive congression and alignment. We find acentrics efficiently align on the metaphase plate, often more rapidly than kinetochore-bearing chromosomes. Unlike intact chromosomes, the paired sister acentrics oscillate as they move to and reside on the metaphase plate in a plane distinct and significantly further from the main mass of intact chromosomes. Consequently, at anaphase onset acentrics are oriented either parallel or perpendicular to the spindle. Parallel-oriented sisters separate by sliding while those oriented perpendicularly separate via unzipping. This oscillation, together with the fact that in monopolar spindles acentrics are rapidly shunted away from the poles, indicates that distributed plus-end directed forces are primarily responsible for acentric migration. This conclusion is supported by the observation that reduction of EB1 preferentially disrupts acentric alignment. In addition, reduction of Klp3a activity, a gene required for the establishment of pole-to-pole microtubules, preferentially disrupts acentric alignment. Taken together these studies suggest that plus-end forces mediated by the outer pole-to-pole microtubules are primarily responsible for acentric metaphase alignment. Surprisingly, we find that a small fraction of sister acentrics are anti-parallel aligned indicating that the kinetochore is required to ensure parallel alignment of sister chromatids. Finally, we find induction of acentric chromosome fragments results in a global reorganization of the congressed chromosomes into a torus configuration. Article Summary The kinetochore serves as a site for attaching microtubules and allows for successful alignment, separation, and segregation of replicated sister chromosomes during cell division. However, previous studies have revealed that sister chromosomes without kinetochores (acentrics) often align to the metaphase plate, undergo separation and segregation, and are properly transmitted to daughter cells. In this study, we discuss the forces acting on chromosomes, independent of the kinetochore, underlying their successful alignment in early mitosis.
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2
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Messer CL, Fox DT. Broken chromosomes heading into mitosis: More than one way to patch a flat tire. J Cell Biol 2024; 223:e202401085. [PMID: 38477879 PMCID: PMC10937182 DOI: 10.1083/jcb.202401085] [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: 01/17/2024] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
A cell dealing with a broken chromosome in mitosis is like a driver dealing with a flat tire on the highway: damage repair must occur under non-ideal circumstances. Mitotic chromosome breaks encounter problems related to structures called micronuclei. These aberrant nuclei are linked to cell death, mutagenesis, and cancer. In the last few years, a flurry of studies illuminated two mechanisms that prevent mitotic problems related to micronuclei. One mechanism prevents micronuclei from forming during mitosis and involves DNA Polymerase Theta, a DNA repair regulator that patches up broken mitotic chromosomes. A second mechanism is activated after micronuclei form and then rupture, and involves CIP2A and TOPBP1 proteins, which patch micronuclear fragments to promote their subsequent mitotic segregation. Here, we review recent progress in this field of mitotic DNA damage and discuss why multiple mechanisms exist. Future studies in this exciting area will reveal new DNA break responses and inform therapeutic strategies.
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Affiliation(s)
- C. Luke Messer
- Department of Biology, St. Bonaventure University, St. Bonaventure, NY, USA
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Donald T. Fox
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
- Duke Regeneration Center, Duke University Medical Center, Durham, NC, USA
- Duke Cancer Institute, Duke University Medical Center, Durham, NC, USA
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3
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Graham EL, Fernandez J, Gandhi S, Choudhry I, Kellam N, LaRocque JR. The impact of developmental stage, tissue type, and sex on DNA double-strand break repair in Drosophila melanogaster. PLoS Genet 2024; 20:e1011250. [PMID: 38683763 PMCID: PMC11057719 DOI: 10.1371/journal.pgen.1011250] [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: 12/15/2023] [Accepted: 04/04/2024] [Indexed: 05/02/2024] Open
Abstract
Accurate repair of DNA double-strand breaks (DSBs) is essential for the maintenance of genome integrity, as failure to repair DSBs can result in cell death. The cell has evolved two main mechanisms for DSB repair: non-homologous end-joining (NHEJ) and homology-directed repair (HDR), which includes single-strand annealing (SSA) and homologous recombination (HR). While certain factors like age and state of the chromatin are known to influence DSB repair pathway choice, the roles of developmental stage, tissue type, and sex have yet to be elucidated in multicellular organisms. To examine the influence of these factors, DSB repair in various embryonic developmental stages, larva, and adult tissues in Drosophila melanogaster was analyzed through molecular analysis of the DR-white assay using Tracking across Indels by DEcomposition (TIDE). The proportion of HR repair was highest in tissues that maintain the canonical (G1/S/G2/M) cell cycle and suppressed in both terminally differentiated and polyploid tissues. To determine the impact of sex on repair pathway choice, repair in different tissues in both males and females was analyzed. When molecularly examining tissues containing mostly somatic cells, males and females demonstrated similar proportions of HR and NHEJ. However, when DSB repair was analyzed in male and female premeiotic germline cells utilizing phenotypic analysis of the DR-white assay, there was a significant decrease in HR in females compared to males. This study describes the impact of development, tissue-specific cycling profile, and, in some cases, sex on DSB repair outcomes, underscoring the complexity of repair in multicellular organisms.
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Affiliation(s)
- Elizabeth L. Graham
- Department of Human Science, School of Health, Georgetown University Medical Center, Washington, District of Columbia, United States of America
| | - Joel Fernandez
- Department of Human Science, School of Health, Georgetown University Medical Center, Washington, District of Columbia, United States of America
| | - Shagun Gandhi
- Department of Human Science, School of Health, Georgetown University Medical Center, Washington, District of Columbia, United States of America
| | - Iqra Choudhry
- Department of Human Science, School of Health, Georgetown University Medical Center, Washington, District of Columbia, United States of America
| | - Natalia Kellam
- Department of Human Science, School of Health, Georgetown University Medical Center, Washington, District of Columbia, United States of America
| | - Jeannine R. LaRocque
- Department of Human Science, School of Health, Georgetown University Medical Center, Washington, District of Columbia, United States of America
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4
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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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5
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Wang Y, Tamori Y. Polyploid Cancer Cell Models in Drosophila. Genes (Basel) 2024; 15:96. [PMID: 38254985 PMCID: PMC10815460 DOI: 10.3390/genes15010096] [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: 11/06/2023] [Revised: 01/04/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Cells with an abnormal number of chromosomes have been found in more than 90% of solid tumors, and among these, polyploidy accounts for about 40%. Polyploidized cells most often have duplicate centrosomes as well as genomes, and thus their mitosis tends to promote merotelic spindle attachments and chromosomal instability, which produces a variety of aneuploid daughter cells. Polyploid cells have been found highly resistant to various stress and anticancer therapies, such as radiation and mitogenic inhibitors. In other words, common cancer therapies kill proliferative diploid cells, which make up the majority of cancer tissues, while polyploid cells, which lurk in smaller numbers, may survive. The surviving polyploid cells, prompted by acute environmental changes, begin to mitose with chromosomal instability, leading to an explosion of genetic heterogeneity and a concomitant cell competition and adaptive evolution. The result is a recurrence of the cancer during which the tenacious cells that survived treatment express malignant traits. Although the presence of polyploid cells in cancer tissues has been observed for more than 150 years, the function and exact role of these cells in cancer progression has remained elusive. For this reason, there is currently no effective therapeutic treatment directed against polyploid cells. This is due in part to the lack of suitable experimental models, but recently several models have become available to study polyploid cells in vivo. We propose that the experimental models in Drosophila, for which genetic techniques are highly developed, could be very useful in deciphering mechanisms of polyploidy and its role in cancer progression.
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Affiliation(s)
| | - Yoichiro Tamori
- Department of Molecular Oncology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
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6
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Wang P, Zhao D, Li J, Su J, Zhang C, Li S, Fan F, Dai Z, Liao X, Mao Z, Bi C, Zhang X. Artificial Diploid Escherichia coli by a CRISPR Chromosome-Doubling Technique. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205855. [PMID: 36642845 PMCID: PMC9982549 DOI: 10.1002/advs.202205855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Synthetic biology has been represented by the creation of artificial life forms at the genomic scale. In this work, a CRISPR-based chromosome-doubling technique is designed to first construct an artificial diploid Escherichia coli cell. The stable single-cell diploid E. coli is isolated by both maximal dilution plating and flow cytometry, and confirmed with quantitative PCR, fluorescent in situ hybridization, and third-generation genome sequencing. The diploid E. coli has a greatly reduced growth rate and elongated cells at 4-5 µm. It is robust against radiation, and the survival rate after exposure to UV increased 40-fold relative to WT. As a novel life form, the artificial diploid E. coli is an ideal substrate for research fundamental questions in life science concerning polyploidy. And this technique may be applied to other bacteria.
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Affiliation(s)
- Pengju Wang
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Dongdong Zhao
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Ju Li
- College of Life ScienceTianjin Normal UniversityTianjin300382P. R. China
| | - Junchang Su
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- School of Biological EngineeringDalian Polytechnic UniversityDalian116034P. R. China
| | - Chunzhi Zhang
- School of Biological EngineeringDalian Polytechnic UniversityDalian116034P. R. China
| | - Siwei Li
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Feiyu Fan
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Zhubo Dai
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Xiaoping Liao
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Biodesign CenterKey Laboratory of Systems Microbial BiotechnologyTianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Zhitao Mao
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Biodesign CenterKey Laboratory of Systems Microbial BiotechnologyTianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Changhao Bi
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
| | - Xueli Zhang
- Tianjin Institute of Industrial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
- Key Laboratory of Systems Microbial BiotechnologyChinese Academy of SciencesTianjin300308P. R. China
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7
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Warecki B, Bast I, Tajima M, Sullivan W. Connections between sister and non-sister telomeres of segregating chromatids maintain euploidy. Curr Biol 2023; 33:58-74.e5. [PMID: 36525974 PMCID: PMC9839490 DOI: 10.1016/j.cub.2022.11.038] [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: 05/04/2022] [Revised: 10/05/2022] [Accepted: 11/17/2022] [Indexed: 12/23/2022]
Abstract
The complete separation of sister chromatids during anaphase is a fundamental requirement for successful mitosis. Therefore, divisions with either persistent DNA-based connections or lagging chromosome fragments threaten aneuploidy if unresolved. Here, we demonstrate the existence of an anaphase mechanism in normally dividing cells in which pervasive connections between telomeres of segregating chromosomes aid in rescuing lagging chromosome fragments. We observe that in a large proportion of Drosophila melanogaster neuronal stem cell divisions, early anaphase sister and non-sister chromatids remain connected by thin telomeric DNA threads. Normally, these threads are resolved in mid-to-late anaphase via a spatial mechanism. However, we find that the presence of a nearby unrepaired DNA break recruits histones, BubR1 kinase, Polo kinase, Aurora B kinase, and BAF to the telomeric thread of the broken chromosome, stabilizing it. Stabilized connections then aid lagging chromosome rescue. These results suggest a model in which pervasive anaphase telomere-telomere connections that are normally resolved quickly can instead be stabilized to retain wayward chromosome fragments. Thus, the liability of persistent anaphase inter-chromosomal connections in normal divisions may be offset by their ability to maintain euploidy in the face of chromosome damage and genome loss.
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Affiliation(s)
- Brandt Warecki
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| | - Ian Bast
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Matthew Tajima
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
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8
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Clay DE, Jezuit EA, Montague RA, Fox DT. Conserved function of Drosophila Fancd2 monoubiquitination in response to double-strand DNA breaks. G3 (BETHESDA, MD.) 2022; 12:6589893. [PMID: 35595243 PMCID: PMC9339327 DOI: 10.1093/g3journal/jkac129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/12/2022] [Indexed: 11/12/2022]
Abstract
Fanconi anemia genes play key roles in metazoan DNA damage responses, and human FA mutations cause numerous disease phenotypes. In human cells, activating monoubiquitination of the Fanconi anemia protein Fancd2 occurs following diverse DNA damage stimuli. Monoubiquitinated Fancd2 forms nuclear foci to recruit additional repair factors. Fancd2 animal models to date have focused on molecular nulls or whole gene knockdown, leaving the specific in vivo role of monoubiquitination unclear. Using a point mutant in a conserved residue, we recently linked Drosophila Fancd2 monoubiquitination to a mitosis-specific DNA double-strand break response. In this context, we used CRISPR/Cas9 to generate the first animal model of an endogenous mutation in the conserved monoubiquitination site (fancd2K595R). Here, we expand upon our characterization of fancd2K595R. We also introduce and characterize additional Drosophila tools to study fancd2, including new mutant alleles and GFP-tagged rescue transgenes. Using these new reagents, we show the impact of Drosophila Fancd2 on organismal and cell viability, as well as on repair protein localization, in the presence or absence of double-strand breaks. These findings expand our understanding of Fanconi anemia gene function in vivo and provide useful reagents for DNA repair research.
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Affiliation(s)
- Delisa E Clay
- Department of Pharmacology and Cancer Biology, C318 Levine Science Research Center, Duke University Medical School, Durham, NC 27710, USA
| | - Erin A Jezuit
- Department of Pharmacology and Cancer Biology, C318 Levine Science Research Center, Duke University Medical School, Durham, NC 27710, USA
| | - Ruth A Montague
- Department of Pharmacology and Cancer Biology, C318 Levine Science Research Center, Duke University Medical School, Durham, NC 27710, USA
| | - Donald T Fox
- Corresponding author: Department of Pharmacology and Cancer Biology, C318 Levine Science Research Center, DUMC Box 3813, Duke University Medical School, Durham, NC 27710, USA.
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9
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Warecki B, Sullivan W. The Cell Biology of Heterochromatin. Cells 2022; 11:cells11071247. [PMID: 35406810 PMCID: PMC8997597 DOI: 10.3390/cells11071247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/30/2021] [Accepted: 01/04/2022] [Indexed: 12/10/2022] Open
Abstract
A conserved feature of virtually all higher eukaryotes is that the centromeres are embedded in heterochromatin. Here we provide evidence that this tight association between pericentric heterochromatin and the centromere is essential for proper metaphase exit and progression into telophase. Analysis of chromosome rearrangements that separate pericentric heterochromatin and centromeres indicates that they must remain associated in order to balance Cohesin/DNA catenation-based binding forces and centromere-based pulling forces during the metaphase–anaphase transition. In addition, a centromere embedded in heterochromatin facilitates nuclear envelope assembly around the entire complement of segregating chromosomes. Because the nuclear envelope initially forms on pericentric heterochromatin, nuclear envelope formation proceeds from the pole, thus providing time for incorporation of lagging and trailing chromosome arms into the newly formed nucleus. Additional analysis of noncanonical mitoses provides further insights into the functional significance of the tight association between heterochromatin and centromeres.
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10
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Clay DE, Bretscher HS, Jezuit EA, Bush KB, Fox DT. Persistent DNA damage signaling and DNA polymerase theta promote broken chromosome segregation. J Cell Biol 2021; 220:e202106116. [PMID: 34613334 PMCID: PMC8500225 DOI: 10.1083/jcb.202106116] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/24/2021] [Accepted: 09/14/2021] [Indexed: 01/16/2023] Open
Abstract
Cycling cells must respond to DNA double-strand breaks (DSBs) to avoid genome instability. Missegregation of chromosomes with DSBs during mitosis results in micronuclei, aberrant structures linked to disease. How cells respond to DSBs during mitosis is incompletely understood. We previously showed that Drosophilamelanogaster papillar cells lack DSB checkpoints (as observed in many cancer cells). Here, we show that papillar cells still recruit early acting repair machinery (Mre11 and RPA3) and the Fanconi anemia (FA) protein Fancd2 to DSBs. These proteins persist as foci on DSBs as cells enter mitosis. Repair foci are resolved in a stepwise manner during mitosis. DSB repair kinetics depends on both monoubiquitination of Fancd2 and the alternative end-joining protein DNA polymerase θ. Disruption of either or both of these factors causes micronuclei after DNA damage, which disrupts intestinal organogenesis. This study reveals a mechanism for how cells with inactive DSB checkpoints can respond to DNA damage that persists into mitosis.
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Affiliation(s)
- Delisa E. Clay
- Department of Cell Biology, Duke University School of Medicine, Durham, NC
| | - Heidi S. Bretscher
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
| | - Erin A. Jezuit
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
| | - Korie B. Bush
- University Program in Genetics and Genomics, Duke University School of Medicine, Durham, NC
| | - Donald T. Fox
- Department of Cell Biology, Duke University School of Medicine, Durham, NC
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC
- University Program in Genetics and Genomics, Duke University School of Medicine, Durham, NC
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11
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Zhan S, Siu J, Wang Z, Yu H, Bezabeh T, Deng Y, Du W, Fei P. Focal Point of Fanconi Anemia Signaling. Int J Mol Sci 2021; 22:12976. [PMID: 34884777 PMCID: PMC8657418 DOI: 10.3390/ijms222312976] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/26/2021] [Accepted: 11/26/2021] [Indexed: 12/11/2022] Open
Abstract
Among human genetic diseases, Fanconi Anemia (FA) tops all with its largest number of health complications in nearly all human organ systems, suggesting the significant roles played by FA genes in the maintenance of human health. With the accumulated research on FA, the encoded protein products by FA genes have been building up to the biggest cell defense signaling network, composed of not only 22+ FA proteins but also ATM, ATR, and many other non-FA proteins. The FA D2 group protein (FANCD2) and its paralog form the focal point of FA signaling to converge the effects of its upstream players in response to a variety of cellular insults and simultaneously with downstream players to protect humans from contracting diseases, including aging and cancer. In this review, we update and discuss how the FA signaling crucially eases cellular stresses through understanding its focal point.
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Affiliation(s)
- Sudong Zhan
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI 96813, USA; (S.Z.); (Z.W.); (H.Y.)
| | - Jolene Siu
- Student Research Experience Program of University of Hawaii, Honolulu, HI 96822, USA;
| | - Zhanwei Wang
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI 96813, USA; (S.Z.); (Z.W.); (H.Y.)
| | - Herbert Yu
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI 96813, USA; (S.Z.); (Z.W.); (H.Y.)
| | - Tedros Bezabeh
- Department of Chemistry, University of Guam, Mangilao, GU 96923, USA;
| | - Youping Deng
- Department of Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA;
| | - Wei Du
- Division of Hematology and Oncology, University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, Pittsburgh, PA 15232, USA;
| | - Peiwen Fei
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI 96813, USA; (S.Z.); (Z.W.); (H.Y.)
- Student Research Experience Program of University of Hawaii, Honolulu, HI 96822, USA;
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12
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Clay DE, Fox DT. DNA Damage Responses during the Cell Cycle: Insights from Model Organisms and Beyond. Genes (Basel) 2021; 12:1882. [PMID: 34946831 PMCID: PMC8701014 DOI: 10.3390/genes12121882] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/25/2022] Open
Abstract
Genome damage is a threat to all organisms. To respond to such damage, DNA damage responses (DDRs) lead to cell cycle arrest, DNA repair, and cell death. Many DDR components are highly conserved, whereas others have adapted to specific organismal needs. Immense progress in this field has been driven by model genetic organism research. This review has two main purposes. First, we provide a survey of model organism-based efforts to study DDRs. Second, we highlight how model organism study has contributed to understanding how specific DDRs are influenced by cell cycle stage. We also look forward, with a discussion of how future study can be expanded beyond typical model genetic organisms to further illuminate how the genome is protected.
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Affiliation(s)
- Delisa E. Clay
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA;
| | - Donald T. Fox
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA;
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
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13
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Almeida Machado Costa C, Wang XF, Ellsworth C, Deng WM. Polyploidy in development and tumor models in Drosophila. Semin Cancer Biol 2021; 81:106-118. [PMID: 34562587 DOI: 10.1016/j.semcancer.2021.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 09/03/2021] [Accepted: 09/18/2021] [Indexed: 12/26/2022]
Abstract
Polyploidy, a cell status defined as more than two sets of genomic DNA, is a conserved strategy across species that can increase cell size and biosynthetic production, but the functional aspects of polyploidy are nuanced and vary across cell types. Throughout Drosophila developmental stages (embryo, larva, pupa and adult), polyploid cells are present in numerous organs and help orchestrate development while contributing to normal growth, well-being and homeostasis of the organism. Conversely, increasing evidence has shown that polyploid cells are prevalent in Drosophila tumors and play important roles in tumor growth and invasiveness. Here, we summarize the genes and pathways involved in polyploidy during normal and tumorigenic development, the mechanisms underlying polyploidization, and the functional aspects of polyploidy in development, homeostasis and tumorigenesis in the Drosophila model.
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Affiliation(s)
- Caique Almeida Machado Costa
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, United States
| | - Xian-Feng Wang
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, United States
| | - Calder Ellsworth
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, United States
| | - Wu-Min Deng
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, United States.
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14
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Wang XF, Yang SA, Gong S, Chang CH, Portilla JM, Chatterjee D, Irianto J, Bao H, Huang YC, Deng WM. Polyploid mitosis and depolyploidization promote chromosomal instability and tumor progression in a Notch-induced tumor model. Dev Cell 2021; 56:1976-1988.e4. [PMID: 34146466 DOI: 10.1016/j.devcel.2021.05.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/18/2021] [Accepted: 05/27/2021] [Indexed: 02/07/2023]
Abstract
Ploidy variation is a cancer hallmark and is frequently associated with poor prognosis in high-grade cancers. Using a Drosophila solid-tumor model where oncogenic Notch drives tumorigenesis in a transition-zone microenvironment in the salivary gland imaginal ring, we find that the tumor-initiating cells normally undergo endoreplication to become polyploid. Upregulation of Notch signaling, however, induces these polyploid transition-zone cells to re-enter mitosis and undergo tumorigenesis. Growth and progression of the transition-zone tumor are fueled by a combination of polyploid mitosis, endoreplication, and depolyploidization. Both polyploid mitosis and depolyploidization are error prone, resulting in chromosomal copy-number variation and polyaneuploidy. Comparative RNA-seq and epistasis analysis reveal that the DNA-damage response genes, also active during meiosis, are upregulated in these tumors and are required for the ploidy-reduction division. Together, these findings suggest that polyploidy and associated cell-cycle variants are critical for increased tumor-cell heterogeneity and genome instability during cancer progression.
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Affiliation(s)
- Xian-Feng Wang
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Sheng-An Yang
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Shangyu Gong
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Chih-Hsuan Chang
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Juan Martin Portilla
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Deeptiman Chatterjee
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Jerome Irianto
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA
| | - Hongcun Bao
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Yi-Chun Huang
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Wu-Min Deng
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA; Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
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15
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Vicars H, Karg T, Warecki B, Bast I, Sullivan W. Kinetochore-independent mechanisms of sister chromosome separation. PLoS Genet 2021; 17:e1009304. [PMID: 33513180 PMCID: PMC7886193 DOI: 10.1371/journal.pgen.1009304] [Citation(s) in RCA: 3] [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: 08/11/2020] [Revised: 02/16/2021] [Accepted: 12/08/2020] [Indexed: 11/19/2022] Open
Abstract
Although kinetochores normally play a key role in sister chromatid separation and segregation, chromosome fragments lacking kinetochores (acentrics) can in some cases separate and segregate successfully. In Drosophila neuroblasts, acentric chromosomes undergo delayed, but otherwise normal sister separation, revealing the existence of kinetochore- independent mechanisms driving sister chromosome separation. Bulk cohesin removal from the acentric is not delayed, suggesting factors other than cohesin are responsible for the delay in acentric sister separation. In contrast to intact kinetochore-bearing chromosomes, we discovered that acentrics align parallel as well as perpendicular to the mitotic spindle. In addition, sister acentrics undergo unconventional patterns of separation. For example, rather than the simultaneous separation of sisters, acentrics oriented parallel to the spindle often slide past one another toward opposing poles. To identify the mechanisms driving acentric separation, we screened 117 RNAi gene knockdowns for synthetic lethality with acentric chromosome fragments. In addition to well-established DNA repair and checkpoint mutants, this candidate screen identified synthetic lethality with X-chromosome-derived acentric fragments in knockdowns of Greatwall (cell cycle kinase), EB1 (microtubule plus-end tracking protein), and Map205 (microtubule-stabilizing protein). Additional image-based screening revealed that reductions in Topoisomerase II levels disrupted sister acentric separation. Intriguingly, live imaging revealed that knockdowns of EB1, Map205, and Greatwall preferentially disrupted the sliding mode of sister acentric separation. Based on our analysis of EB1 localization and knockdown phenotypes, we propose that in the absence of a kinetochore, microtubule plus-end dynamics provide the force to resolve DNA catenations required for sister separation.
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Affiliation(s)
- Hannah Vicars
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Travis Karg
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Brandt Warecki
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Ian Bast
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - William Sullivan
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
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16
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Warecki B, Ling X, Bast I, Sullivan W. ESCRT-III-mediated membrane fusion drives chromosome fragments through nuclear envelope channels. J Cell Biol 2020; 219:133702. [PMID: 32032426 PMCID: PMC7054997 DOI: 10.1083/jcb.201905091] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 11/05/2019] [Accepted: 12/18/2019] [Indexed: 12/24/2022] Open
Abstract
Mitotic cells must form a single nucleus during telophase or exclude part of their genome as damage-prone micronuclei. While research has detailed how micronuclei arise from cells entering anaphase with lagging chromosomes, cellular mechanisms allowing late-segregating chromosomes to rejoin daughter nuclei remain underexplored. Here, we find that late-segregating acentric chromosome fragments that rejoin daughter nuclei are associated with nuclear membrane but devoid of lamin and nuclear pore complexes in Drosophila melanogaster. We show that acentrics pass through membrane-, lamin-, and nuclear pore-based channels in the nuclear envelope that extend and retract as acentrics enter nuclei. Membrane encompassing the acentrics fuses with the nuclear membrane, facilitating integration of the acentrics into newly formed nuclei. Fusion, mediated by the membrane fusion protein Comt/NSF and ESCRT-III components Shrub/CHMP4B and CHMP2B, facilitates reintegration of acentrics into nuclei. These results suggest a previously unsuspected role for membrane fusion, similar to nuclear repair, in the formation of a single nucleus during mitotic exit and the maintenance of genomic integrity.
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Affiliation(s)
- Brandt Warecki
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA
| | - Xi Ling
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA
| | - Ian Bast
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA
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17
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Gemble S, Basto R. CHRONOCRISIS: When Cell Cycle Asynchrony Generates DNA Damage in Polyploid Cells. Bioessays 2020; 42:e2000105. [PMID: 32885500 DOI: 10.1002/bies.202000105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/19/2020] [Indexed: 12/16/2022]
Abstract
Polyploid cells contain multiple copies of all chromosomes. Polyploidization can be developmentally programmed to sustain tissue barrier function or to increase metabolic potential and cell size. Programmed polyploidy is normally associated with terminal differentiation and poor proliferation capacity. Conversely, non-programmed polyploidy can give rise to cells that retain the ability to proliferate. This can fuel rapid genome rearrangements and lead to diseases like cancer. Here, the mechanisms that generate polyploidy are reviewed and the possible challenges upon polyploid cell division are discussed. The discussion is framed around a recent study showing that asynchronous cell cycle progression (an event that is named "chronocrisis") of different nuclei from a polyploid cell can generate DNA damage at mitotic entry. The potential mechanisms explaining how mitosis in non-programmed polyploid cells can generate abnormal karyotypes and genetic instability are highlighted.
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Affiliation(s)
- Simon Gemble
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, Paris, 75005, France
| | - Renata Basto
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, Paris, 75005, France
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18
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Nandakumar S, Grushko O, Buttitta LA. Polyploidy in the adult Drosophila brain. eLife 2020; 9:e54385. [PMID: 32840209 PMCID: PMC7447450 DOI: 10.7554/elife.54385] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Long-lived cells such as terminally differentiated postmitotic neurons and glia must cope with the accumulation of damage over the course of an animal's lifespan. How long-lived cells deal with ageing-related damage is poorly understood. Here we show that polyploid cells accumulate in the adult fly brain and that polyploidy protects against DNA damage-induced cell death. Multiple types of neurons and glia that are diploid at eclosion, become polyploid in the adult Drosophila brain. The optic lobes exhibit the highest levels of polyploidy, associated with an elevated DNA damage response in this brain region. Inducing oxidative stress or exogenous DNA damage leads to an earlier onset of polyploidy, and polyploid cells in the adult brain are more resistant to DNA damage-induced cell death than diploid cells. Our results suggest polyploidy may serve a protective role for neurons and glia in adult Drosophila melanogaster brains.
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Affiliation(s)
- Shyama Nandakumar
- Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
| | - Olga Grushko
- Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
| | - Laura A Buttitta
- Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
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19
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Warecki B, Sullivan W. Mechanisms driving acentric chromosome transmission. Chromosome Res 2020; 28:229-246. [PMID: 32712740 DOI: 10.1007/s10577-020-09636-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/16/2020] [Accepted: 07/19/2020] [Indexed: 02/07/2023]
Abstract
The kinetochore-microtubule association is a core, conserved event that drives chromosome transmission during mitosis. Failure to establish this association on even a single chromosome results in aneuploidy leading to cell death or the development of cancer. However, although many chromosomes lacking centromeres, termed acentrics, fail to segregate, studies in a number of systems reveal robust alternative mechanisms that can drive segregation and successful poleward transport of acentrics. In contrast to the canonical mechanism that relies on end-on microtubule attachments to kinetochores, mechanisms of acentric transmission largely fall into three categories: direct attachments to other chromosomes, kinetochore-independent lateral attachments to microtubules, and long-range tether-based attachments. Here, we review these "non-canonical" methods of acentric chromosome transmission. Just as the discovery and exploration of cell cycle checkpoints provided insight into both the origins of cancer and new therapies, identifying mechanisms and structures specifically involved in acentric segregation may have a significant impact on basic and applied cancer research.
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Affiliation(s)
- Brandt Warecki
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, USA.
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20
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Ren D, Song J, Ni M, Kang L, Guo W. Regulatory Mechanisms of Cell Polyploidy in Insects. Front Cell Dev Biol 2020; 8:361. [PMID: 32548115 PMCID: PMC7272692 DOI: 10.3389/fcell.2020.00361] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 04/22/2020] [Indexed: 12/14/2022] Open
Abstract
Polyploidy cells undergo the endocycle to generate DNA amplification without cell division and have important biological functions in growth, development, reproduction, immune response, nutrient support, and conferring resistance to DNA damage in animals. In this paper, we have specially summarized current research progresses in the regulatory mechanisms of cell polyploidy in insects. First, insect hormones including juvenile hormone and 20-hydroxyecdysone regulate the endocycle of variant cells in diverse insect species. Second, cells skip mitotic division in response to developmental programming and conditional stimuli such as wound healing, regeneration, and aging. Third, the reported regulatory pathways of mitotic to endocycle switch (MES), including Notch, Hippo, and JNK signaling pathways, are summarized and constructed into genetic network. Thus, we think that the studies in crosstalk of hormones and their effects on canonical pathways will shed light on the mechanism of cell polyploidy and elucidate the evolutionary adaptions of MES through diverse insect species.
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Affiliation(s)
- Dani Ren
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Juan Song
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Ming Ni
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, Hebei University, Baoding, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, Hebei University, Baoding, China
| | - Wei Guo
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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21
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Stolyarenko AD. Nuclear Argonaute Piwi Gene Mutation Affects rRNA by Inducing rRNA Fragment Accumulation, Antisense Expression, and Defective Processing in Drosophila Ovaries. Int J Mol Sci 2020; 21:ijms21031119. [PMID: 32046213 PMCID: PMC7037970 DOI: 10.3390/ijms21031119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/27/2020] [Accepted: 02/04/2020] [Indexed: 12/26/2022] Open
Abstract
Drosophila key nuclear piRNA silencing pathway protein Piwi of the Argonaute family has been classically studied as a factor controlling transposable elements and fertility. Piwi has been shown to concentrate in the nucleolus for reasons largely unknown. Ribosomal RNA is the main component of the nucleolus. In this work the effect of a piwi mutation on rRNA is described. This work led to three important conclusions: A mutation in piwi induces antisense 5S rRNA expression, a processing defect of 2S rRNA orthologous to the 3′-end of eukaryotic 5.8S rRNA, and accumulation of fragments of all five rRNAs in Drosophilamelanogaster ovaries. Hypotheses to explain these phenomena are proposed, possibly involving the interaction of the components of the piRNA pathway with the RNA surveillance machinery.
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Affiliation(s)
- Anastasia D Stolyarenko
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., Moscow 123182, Russia
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22
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Cohen E, Sawyer JK, Peterson NG, Dow JAT, Fox DT. Physiology, Development, and Disease Modeling in the Drosophila Excretory System. Genetics 2020; 214:235-264. [PMID: 32029579 PMCID: PMC7017010 DOI: 10.1534/genetics.119.302289] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
The insect excretory system contains two organ systems acting in concert: the Malpighian tubules and the hindgut perform essential roles in excretion and ionic and osmotic homeostasis. For over 350 years, these two organs have fascinated biologists as a model of organ structure and function. As part of a recent surge in interest, research on the Malpighian tubules and hindgut of Drosophila have uncovered important paradigms of organ physiology and development. Further, many human disease processes can be modeled in these organs. Here, focusing on discoveries in the past 10 years, we provide an overview of the anatomy and physiology of the Drosophila excretory system. We describe the major developmental events that build these organs during embryogenesis, remodel them during metamorphosis, and repair them following injury. Finally, we highlight the use of the Malpighian tubules and hindgut as accessible models of human disease biology. The Malpighian tubule is a particularly excellent model to study rapid fluid transport, neuroendocrine control of renal function, and modeling of numerous human renal conditions such as kidney stones, while the hindgut provides an outstanding model for processes such as the role of cell chirality in development, nonstem cell-based injury repair, cancer-promoting processes, and communication between the intestine and nervous system.
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Affiliation(s)
| | - Jessica K Sawyer
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, and
| | | | - Julian A T Dow
- Institute of Molecular, Cell, and Systems Biology, University of Glasgow, G12 8QQ, United Kingdom
| | - Donald T Fox
- Department of Cell Biology and
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, and
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23
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Peterson NG, Stormo BM, Schoenfelder KP, King JS, Lee RRS, Fox DT. Cytoplasmic sharing through apical membrane remodeling. eLife 2020; 9:58107. [PMID: 33051002 PMCID: PMC7655102 DOI: 10.7554/elife.58107] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 10/13/2020] [Indexed: 12/12/2022] Open
Abstract
Multiple nuclei sharing a common cytoplasm are found in diverse tissues, organisms, and diseases. Yet, multinucleation remains a poorly understood biological property. Cytoplasm sharing invariably involves plasma membrane breaches. In contrast, we discovered cytoplasm sharing without membrane breaching in highly resorptive Drosophila rectal papillae. During a six-hour developmental window, 100 individual papillar cells assemble a multinucleate cytoplasm, allowing passage of proteins of at least 62 kDa throughout papillar tissue. Papillar cytoplasm sharing does not employ canonical mechanisms such as incomplete cytokinesis or muscle fusion pore regulators. Instead, sharing requires gap junction proteins (normally associated with transport of molecules < 1 kDa), which are positioned by membrane remodeling GTPases. Our work reveals a new role for apical membrane remodeling in converting a multicellular epithelium into a giant multinucleate cytoplasm.
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Affiliation(s)
- Nora G Peterson
- Department of Cell Biology, Duke University Medical CenterDurhamUnited States
| | - Benjamin M Stormo
- Department of Cell Biology, Duke University Medical CenterDurhamUnited States
| | | | - Juliet S King
- Department of Pharmacology & Cancer Biology, Duke University Medical CenterDurhamUnited States
| | | | - Donald T Fox
- Department of Cell Biology, Duke University Medical CenterDurhamUnited States,University Program in Genetics and Genomics, Duke UniversityDurhamUnited States,Department of Pharmacology & Cancer Biology, Duke University Medical CenterDurhamUnited States
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24
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Nano M, Gemble S, Simon A, Pennetier C, Fraisier V, Marthiens V, Basto R. Cell-Cycle Asynchrony Generates DNA Damage at Mitotic Entry in Polyploid Cells. Curr Biol 2019; 29:3937-3945.e7. [PMID: 31708395 DOI: 10.1016/j.cub.2019.09.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/29/2019] [Accepted: 09/16/2019] [Indexed: 01/17/2023]
Abstract
Polyploidy arises from the gain of complete chromosome sets [1], and it is known to promote cancer genome evolution. Recent evidence suggests that a large proportion of human tumors experience whole-genome duplications (WGDs), which might favor the generation of highly abnormal karyotypes within a short time frame, rather than in a stepwise manner [2-6]. However, the molecular mechanisms linking whole-genome duplication to genetic instability remain poorly understood. Using repeated cytokinesis failure to induce polyploidization of Drosophila neural stem cells (NSCs) (also called neuroblasts [NBs]), we investigated the consequences of polyploidy in vivo. Surprisingly, we found that DNA damage is generated in a subset of nuclei of polyploid NBs during mitosis. Importantly, our observations in flies were confirmed in mouse NSCs (mNSCs) and human cancer cells after acute cytokinesis inhibition. Interestingly, DNA damage occurs in nuclei that were not ready to enter mitosis but were forced to do so when exposed to the mitotic environment of neighboring nuclei within the same cell. Additionally, we found that polyploid cells are cell-cycle asynchronous and forcing cell-cycle synchronization was sufficient to lower the levels of DNA damage generated during mitosis. Overall, this work supports a model in which DNA damage at mitotic entry can generate DNA structural abnormalities that might contribute to the onset of genetic instability.
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Affiliation(s)
- Maddalena Nano
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France.
| | - Simon Gemble
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France
| | - Anthony Simon
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France
| | - Carole Pennetier
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France
| | - Vincent Fraisier
- Plateforme Imagerie PICT-IBiSA, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France
| | - Veronique Marthiens
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France
| | - Renata Basto
- Biology of Centrosomes and Genetic Instability Lab, Institut Curie, PSL Research University, CNRS UMR144, 12 rue Lhomond, 75005 Paris, France.
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25
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Stormo BM, Fox DT. Interphase cohesin regulation ensures mitotic fidelity after genome reduplication. Mol Biol Cell 2019; 30:219-227. [PMID: 30462577 PMCID: PMC6589556 DOI: 10.1091/mbc.e17-10-0582] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 10/17/2018] [Accepted: 11/15/2018] [Indexed: 12/24/2022] Open
Abstract
To ensure faithful genome propagation, mitotic cells alternate one round of chromosome duplication with one round of chromosome separation. Chromosome separation failure thus causes genome reduplication, which alters mitotic chromosome structure. Such structural alterations are well documented to impair mitotic fidelity following aberrant genome reduplication, including in diseased states. In contrast, we recently showed that naturally occurring genome reduplication does not alter mitotic chromosome structure in Drosophila papillar cells. Our discovery raised the question of how a cell undergoing genome reduplication might regulate chromosome structure to prevent mitotic errors. Here, we show that papillar cells ensure mitotic fidelity through interphase cohesin regulation. We demonstrate a requirement for cohesins during programmed rounds of papillar genome reduplication known as endocycles. This interphase cohesin regulation relies on cohesin release but not cohesin cleavage and depends on the conserved cohesin regulator Pds5 . Our data suggest that a distinct form of interphase cohesin regulation ensures mitotic fidelity after genome reduplication.
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Affiliation(s)
- Benjamin M. Stormo
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710
| | - Donald T. Fox
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710
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26
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Gjelsvik KJ, Besen-McNally R, Losick VP. Solving the Polyploid Mystery in Health and Disease. Trends Genet 2019; 35:6-14. [PMID: 30470486 PMCID: PMC6457904 DOI: 10.1016/j.tig.2018.10.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/12/2018] [Accepted: 10/22/2018] [Indexed: 01/12/2023]
Abstract
Polyploidy (the more than doubling of a cell's genome) frequently arises during organogenesis, tissue repair, and age-associated diseases. Despite its prevalence, major gaps exist in how polyploid cells emerge and affect tissue function. Studies have begun to elucidate the signals required for polyploid cell growth as well as the advantages and disadvantages of polyploidy in health and disease. This review highlights the recent advances on the role and regulation of polyploidy in Drosophila and vertebrate models. The newly discovered versatility of polyploid cells has the potential to provide alternative strategies to promote tissue growth and repair, while limiting disease and dysfunction.
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Affiliation(s)
- K J Gjelsvik
- MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609, USA
| | - R Besen-McNally
- MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609, USA
| | - V P Losick
- MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609, USA.
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27
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Guo X, Ni J, Liang Z, Xue J, Fenech MF, Wang X. The molecular origins and pathophysiological consequences of micronuclei: New insights into an age-old problem. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 779:1-35. [PMID: 31097147 DOI: 10.1016/j.mrrev.2018.11.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 02/07/2023]
Abstract
Micronuclei (MN), the small nucleus-like bodies separated from the primary nucleus, can exist in cells with numerical and/or structural chromosomal aberrations in apparently normal tissues and more so in tumors in humans. While MN have been observed for over 100 years, they were merely and constantly considered as passive indicators of chromosome instability (CIN) for a long time. Relatively little is known about the molecular origins and biological consequences of MN. Rapid technological advances are helping to close these gaps. Very recent studies provide exciting evidence that MN act as key platform for chromothripsis and a trigger of innate immune response, suggesting that MN could affect cellular functions by both genetic and nongenetic means. These previously unappreciated findings have reawakened widespread interests in MN. In this review, the diverse mechanisms leading to MN generation and the complex fate profiles of MN are discussed, together with the evidence for their contribution to CIN, inflammation, senescence and cell death. Moreover, we put this knowledge together into a speculative perspective on how MN may be responsible for cancer development and how their presence may influence the choice of treatment. We suggest that the heterogeneous responses to MN may function physiological to ensure the arrestment, elimination and immune clearance of damaged cells, but pathologically, may enable the survival and oncogenic transformation of cells bearing CIN. These insights not only underscore the complexity of MN biology, but also raise a host of new questions and provide fertile ground for future research.
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Affiliation(s)
- Xihan Guo
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, 650500, China
| | - Juan Ni
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, 650500, China
| | - Ziqing Liang
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, 650500, China
| | - Jinglun Xue
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Michael F Fenech
- University of South Australia, Adelaide, SA, 5000, Australia; Genome Health Foundation, North Brighton, SA, 5048, Australia.
| | - Xu Wang
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, Yunnan, 650500, China.
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Micronuclei Formation Is Prevented by Aurora B-Mediated Exclusion of HP1a from Late-Segregating Chromatin in Drosophila. Genetics 2018; 210:171-187. [PMID: 29986897 PMCID: PMC6116970 DOI: 10.1534/genetics.118.301031] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/03/2018] [Indexed: 11/18/2022] Open
Abstract
While it is known that micronuclei pose a serious risk to genomic integrity by undergoing chromothripsis, mechanisms preventing micronucleus formation remain poorly understood. Here, we investigate how late-segregating acentric chromosomes that would otherwise form micronuclei instead reintegrate into daughter nuclei by passing through Aurora B kinase-dependent channels in the nuclear envelope of Drosophila melanogaster neuroblasts. We find that localized concentrations of Aurora B preferentially phosphorylate H3(S10) on acentrics and their associated DNA tethers. This phosphorylation event prevents HP1a from associating with heterochromatin and results in localized inhibition of nuclear envelope reassembly on endonuclease- and X-irradiation-induced acentrics, promoting channel formation. Finally, we find that HP1a also specifies initiation sites of nuclear envelope reassembly on undamaged chromatin. Taken together, these results demonstrate that Aurora B-mediated regulation of HP1a-chromatin interaction plays a key role in maintaining genome integrity by locally preventing nuclear envelope assembly and facilitating the incorporation of late-segregating acentrics into daughter nuclei.
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29
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Che R, Zhang J, Nepal M, Han B, Fei P. Multifaceted Fanconi Anemia Signaling. Trends Genet 2018; 34:171-183. [PMID: 29254745 PMCID: PMC5858900 DOI: 10.1016/j.tig.2017.11.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 11/28/2017] [Indexed: 01/26/2023]
Abstract
In 1927 Guido Fanconi described a hereditary condition presenting panmyelopathy accompanied by short stature and hyperpigmentation, now better known as Fanconi anemia (FA). With this discovery the genetic and molecular basis underlying FA has emerged as a field of great interest. FA signaling is crucial in the DNA damage response (DDR) to mediate the repair of damaged DNA. This has attracted a diverse range of investigators, especially those interested in aging and cancer. However, recent evidence suggests FA signaling also regulates functions outside the DDR, with implications for many other frontiers of research. We discuss here the characteristics of FA functions and expand upon current perspectives regarding the genetics of FA, indicating that FA plays a role in a myriad of molecular and cellular processes.
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Affiliation(s)
- Raymond Che
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA; Graduate Program of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI, USA
| | - Jun Zhang
- Department of Laboratory Medicine and Pathology, Mayo Clinic Foundation, USA
| | - Manoj Nepal
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA; Graduate Program of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI, USA
| | - Bing Han
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA
| | - Peiwen Fei
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA; Graduate Program of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI, USA.
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30
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Nikitaki Z, Holá M, Donà M, Pavlopoulou A, Michalopoulos I, Angelis KJ, Georgakilas AG, Macovei A, Balestrazzi A. Integrating plant and animal biology for the search of novel DNA damage biomarkers. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 775:21-38. [DOI: 10.1016/j.mrrev.2018.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 01/08/2018] [Accepted: 01/16/2018] [Indexed: 12/11/2022]
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31
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Stormo BM, Fox DT. Polyteny: still a giant player in chromosome research. Chromosome Res 2017; 25:201-214. [PMID: 28779272 PMCID: PMC5768140 DOI: 10.1007/s10577-017-9562-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/19/2017] [Accepted: 07/21/2017] [Indexed: 12/17/2022]
Abstract
In this era of high-resolution mapping of chromosome territories, topological interactions, and chromatin states, it is increasingly appreciated that the positioning of chromosomes and their interactions within the nucleus is critical for cellular function. Due to their large size and distinctive structure, polytene chromosomes have contributed a wealth of knowledge regarding chromosome regulation. In this review, we discuss the diversity of polytene chromosomes in nature and in disease, examine the recurring structural features of polytene chromosomes in terms of what they reveal about chromosome biology, and discuss recent advances regarding how polytene chromosomes are assembled and disassembled. After over 130 years of study, these giant chromosomes are still powerful tools to understand chromosome biology.
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Affiliation(s)
- Benjamin M Stormo
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Donald T Fox
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, 27710, USA.
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32
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Karg T, Elting MW, Vicars H, Dumont S, Sullivan W. The chromokinesin Klp3a and microtubules facilitate acentric chromosome segregation. J Cell Biol 2017; 216:1597-1608. [PMID: 28500183 PMCID: PMC5461011 DOI: 10.1083/jcb.201604079] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 02/03/2017] [Accepted: 04/07/2017] [Indexed: 11/23/2022] Open
Abstract
Although chromosome fragments lacking a centromere would be expected to show severe defects in their segregation during anaphase, they do exhibit poleward movement by an unclear mechanism. Karg et al. now show how microtubules and the chromokinesin Klp3a can work together to successfully segregate chromosome fragments to daughter nuclei. Although poleward segregation of acentric chromosomes is well documented, the underlying mechanisms remain poorly understood. Here, we demonstrate that microtubules play a key role in poleward movement of acentric chromosome fragments generated in Drosophila melanogaster neuroblasts. Acentrics segregate with either telomeres leading or lagging in equal frequency and are preferentially associated with peripheral bundled microtubules. In addition, laser ablation studies demonstrate that segregating acentrics are mechanically associated with microtubules. Finally, we show that successful acentric segregation requires the chromokinesin Klp3a. Reduced Klp3a function results in disorganized interpolar microtubules and shortened spindles. Normally, acentric poleward segregation occurs at the periphery of the spindle in association with interpolar microtubules. In klp3a mutants, acentrics fail to localize and segregate along the peripheral interpolar microtubules and are abnormally positioned in the spindle interior. These studies demonstrate an unsuspected role for interpolar microtubules in driving acentric segregation.
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Affiliation(s)
- Travis Karg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Mary Williard Elting
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143
| | - Hannah Vicars
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Sophie Dumont
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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34
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Stormo BM, Fox DT. Distinct responses to reduplicated chromosomes require distinct Mad2 responses. eLife 2016; 5. [PMID: 27159240 PMCID: PMC4898934 DOI: 10.7554/elife.15204] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/08/2016] [Indexed: 01/17/2023] Open
Abstract
Duplicating chromosomes once each cell cycle produces sister chromatid pairs, which separate accurately at anaphase. In contrast, reduplicating chromosomes without separation frequently produces polytene chromosomes, a barrier to accurate mitosis. Chromosome reduplication occurs in many contexts, including: polytene tissue development, polytene tumors, and following treatment with mitosis-blocking chemotherapeutics. However, mechanisms responding to or resolving polyteny during mitosis are poorly understood. Here, using Drosophila, we uncover two distinct reduplicated chromosome responses. First, when reduplicated polytene chromosomes persist into metaphase, an anaphase delay prevents tissue malformation and apoptosis. Second, reduplicated polytene chromosomes can also separate prior to metaphase through a spindle-independent mechanism termed Separation-Into-Recent-Sisters (SIRS). Both reduplication responses require the spindle assembly checkpoint protein Mad2. While Mad2 delays anaphase separation of metaphase polytene chromosomes, Mad2’s control of overall mitotic timing ensures efficient SIRS. Our results pinpoint mechanisms enabling continued proliferation after genome reduplication, a finding with implications for cancer progression and prevention. DOI:http://dx.doi.org/10.7554/eLife.15204.001 Before a cell divides, it duplicates all its genetic information, which is stored on chromosomes. Then, each chromosome evenly divides into two new cells so that each cell ends up with identical copies of the genetic information. Because the cellular machinery that evenly divides chromosomes is built to recognize chromosomes that were duplicated exactly once, it is important to maintain this pattern of alternating one round of duplication with one round of division. Cells that instead duplicate their chromosomes more than once can make mistakes during division that are associated with diseases such as cancer. Chromosomes with extra duplications are present in normal tissues such as the placenta of mammals. They can also occur in human diseases and may even result from chemotherapy treatment. However, we know almost nothing about how cells respond to these problematic chromosomes when dividing. By studying cells from the Drosophila melanogaster species of fruit fly, Stormo and Fox discovered two distinct ways in which cells respond to extra chromosome duplications. One response occurs in cells that were experimentally engineered to undergo an extra chromosome duplication. These cells delay division so that the chromosome separation machinery can somehow adapt to the challenge of separating more than two chromosome copies at once. The second response occurs in cells that naturally undergo extra chromosome duplications before division. In these cells, Stormo and Fox discovered a new type of chromosome separation, whereby the extra chromosome copies move apart from each other before cell division. In doing so the chromosomes can better interact with the chromosome separation machinery during division. Stormo and Fox also found that a protein named Mad2 is important in both responses, and gives the cell enough time to respond to extra chromosome copies. Without Mad2, the separation of chromosomes with extra duplications is too hasty, and can lead to severe cell division errors and cause organs to form incorrectly. Having uncovered two new responses that cells use to adapt to extra chromosomes, it will now be important to find other proteins like Mad2 that are important in these events. Understanding these processes and the proteins involved in more detail could help to prevent diseases that are associated with extra chromosomes. DOI:http://dx.doi.org/10.7554/eLife.15204.002
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Affiliation(s)
- Benjamin M Stormo
- Department of Cell Biology, Duke University Medical Center, Durham, United States
| | - Donald T Fox
- Department of Cell Biology, Duke University Medical Center, Durham, United States.,Department of Pharamacology and Cancer biology, Duke University Medical Center, Durham, United States
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