1
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Rourke C, Jaramillo-Lambert A. TOP-2 is differentially required for the proper maintenance of the cohesin subunit REC-8 on meiotic chromosomes in Caenorhabditis elegans spermatogenesis and oogenesis. Genetics 2022; 222:iyac120. [PMID: 35951744 PMCID: PMC9526062 DOI: 10.1093/genetics/iyac120] [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: 07/06/2022] [Accepted: 08/01/2022] [Indexed: 11/14/2022] Open
Abstract
During meiotic prophase I, accurate segregation of homologous chromosomes requires the establishment of chromosomes with a meiosis-specific architecture. The sister chromatid cohesin complex and the enzyme Topoisomerase II (TOP-2) are important components of meiotic chromosome architecture, but the relationship of these proteins in the context of meiotic chromosome segregation is poorly defined. Here, we analyzed the role of TOP-2 in the timely release of the sister chromatid cohesin subunit REC-8 during spermatogenesis and oogenesis of Caenorhabditis elegans. We show that there is a different requirement for TOP-2 in meiosis of spermatogenesis and oogenesis. The loss-of-function mutation top-2(it7) results in premature REC-8 removal in spermatogenesis, but not oogenesis. This correlates with a failure to maintain the HORMA-domain proteins HTP-1 and HTP-2 (HTP-1/2) on chromosome axes at diakinesis and mislocalization of the downstream components that control REC-8 release including Aurora B kinase. In oogenesis, top-2(it7) causes a delay in the localization of Aurora B to oocyte chromosomes but can be rescued through premature activation of the maturation promoting factor via knockdown of the inhibitor kinase WEE-1.3. The delay in Aurora B localization is associated with an increase in the length of diakinesis bivalents and wee-1.3 RNAi mediated rescue of Aurora B localization in top-2(it7) is associated with a decrease in diakinesis bivalent length. Our results imply that the sex-specific effects of TOP-2 on REC-8 release are due to differences in the temporal regulation of meiosis and chromosome structure in late prophase I in spermatogenesis and oogenesis.
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Affiliation(s)
- Christine Rourke
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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2
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Topoisomerase II is regulated by translationally controlled tumor protein for cell survival during organ growth in Drosophila. Cell Death Dis 2021; 12:811. [PMID: 34453033 PMCID: PMC8397738 DOI: 10.1038/s41419-021-04091-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 07/28/2021] [Accepted: 08/12/2021] [Indexed: 11/08/2022]
Abstract
Regulation of cell survival is critical for organ development. Translationally controlled tumor protein (TCTP) is a conserved protein family implicated in the control of cell survival during normal development and tumorigenesis. Previously, we have identified a human Topoisomerase II (TOP2) as a TCTP partner, but its role in vivo has been unknown. To determine the significance of this interaction, we examined their roles in developing Drosophila organs. Top2 RNAi in the wing disc leads to tissue reduction and caspase activation, indicating the essential role of Top2 for cell survival. Top2 RNAi in the eye disc also causes loss of eye and head tissues. Tctp RNAi enhances the phenotypes of Top2 RNAi. The depletion of Tctp reduces Top2 levels in the wing disc and vice versa. Wing size is reduced by Top2 overexpression, implying that proper regulation of Top2 level is important for normal organ development. The wing phenotype of Tctp RNAi is partially suppressed by Top2 overexpression. This study suggests that mutual regulation of Tctp and Top2 protein levels is critical for cell survival during organ development.
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3
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Hsu SJ, Stow EC, Simmons JR, Wallace HA, Lopez AM, Stroud S, Labrador M. Mutations in the insulator protein Suppressor of Hairy wing induce genome instability. Chromosoma 2020; 129:255-274. [PMID: 33140220 DOI: 10.1007/s00412-020-00743-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 12/14/2022]
Abstract
Insulator proteins orchestrate the three-dimensional organization of the genome. Insulators function by facilitating communications between regulatory sequences and gene promoters, allowing accurate gene transcription regulation during embryo development and cell differentiation. However, the role of insulator proteins beyond genome organization and transcription regulation remains unclear. Suppressor of Hairy wing [Su(Hw)] is a Drosophila insulator protein that plays an important function in female oogenesis. Here we find that su(Hw) has an unsuspected role in genome stability during cell differentiation. We show that su(Hw) mutant developing egg chambers have poorly formed microtubule organization centers (MTOCs) in the germarium and display mislocalization of the anterior/posterior axis specification factor gurken in later oogenesis stages. Additionally, eggshells from partially rescued su(Hw) mutant female germline exhibit dorsoventral patterning defects. These phenotypes are very similar to phenotypes found in the important class of spindle mutants or in piRNA pathway mutants in Drosophila, in which defects generally result from the failure of germ cells to repair DNA damage. Similarities between mutations in su(Hw) and spindle and piRNA mutants are further supported by an excess of DNA damage in nurse cells, and because Gurken localization defects are partially rescued by mutations in the ATR (mei-41) and Chk1 (grapes) DNA damage response genes. Finally, we also show that su(Hw) mutants produce an elevated number of chromosome breaks in dividing neuroblasts from larval brains. Together, these findings suggest that Su(Hw) is necessary for the maintenance of genome integrity during Drosophila development, in both germline and dividing somatic cells.
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Affiliation(s)
- Shih-Jui Hsu
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Emily C Stow
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - James R Simmons
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Heather A Wallace
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Andrea Mancheno Lopez
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Shannon Stroud
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - Mariano Labrador
- Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, 37996, USA.
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4
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Wormser O, Levy Y, Bakhrat A, Bonaccorsi S, Graziadio L, Gatti M, AbuMadighem A, McKenney RJ, Okada K, El Riati S, Har-Vardi I, Huleihel M, Levitas E, Birk OS, Abdu U. Absence of SCAPER causes male infertility in humans and Drosophila by modulating microtubule dynamics during meiosis. J Med Genet 2020; 58:254-263. [PMID: 32527956 PMCID: PMC10405349 DOI: 10.1136/jmedgenet-2020-106946] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 04/22/2020] [Accepted: 04/25/2020] [Indexed: 12/25/2022]
Abstract
BACKGROUND Mutation in S-phase cyclin A-associated protein rin the endoplasmic reticulum (SCAPER) have been found across ethnicities and have been shown to cause variable penetrance of an array of pathological traits, including intellectual disability, retinitis pigmentosa and ciliopathies. METHODS Human clinical phenotyping, surgical testicular sperm extraction and testicular tissue staining. Generation and analysis of short spindle 3 (ssp3) (SCAPER orthologue) Drosophila CAS9-knockout lines. In vitro microtubule (MT) binding assayed by total internal reflection fluorescence microscopy. RESULTS We show that patients homozygous for a SCAPER mutation lack SCAPER expression in spermatogonia (SPG) and are azoospermic due to early defects in spermatogenesis, leading to the complete absence of meiotic cells. Interestingly, Drosophila null mutants for the ubiquitously expressed ssp3 gene are viable and female fertile but male sterile. We further show that male sterility in ssp3 null mutants is due to failure in both chromosome segregation and cytokinesis. In cells undergoing male meiosis, the MTs emanating from the centrosomes do not appear to interact properly with the chromosomes, which remain dispersed within dividing spermatocytes (SPCs). In addition, mutant SPCs are unable to assemble a normal central spindle and undergo cytokinesis. Consistent with these results, an in vitro assay demonstrated that both SCAPER and Ssp3 directly bind MTs. CONCLUSIONS Our results show that SCAPER null mutations block the entry into meiosis of SPG, causing azoospermia. Null mutations in ssp3 specifically disrupt MT dynamics during male meiosis, leading to sterility. Moreover, both SCAPER and Ssp3 bind MTs in vitro. These results raise the intriguing possibility of a common feature between human and Drosophila meiosis.
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Affiliation(s)
- Ohad Wormser
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ygal Levy
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Anna Bakhrat
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Silvia Bonaccorsi
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza University of Rome, Rome, Italy
| | - Lucia Graziadio
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza University of Rome, Rome, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza University of Rome, Rome, Italy.,Istituto di Biologia e Patologia Molecolari Consiglio Nazionale delle Ricerche, Roma, Italy
| | - Ali AbuMadighem
- Shraga Segal Department of Microbiology, Immunology and Genetics, Ben-Gurion University of the Negev Faculty of Health Sciences, Beer-Sheva, Israel.,The Center of Advanced Research and Education in Reproduction (CARER), Ben-Gurion University of the Negev Faculty of Health Sciences, Beer-Sheva, Israel
| | - Richard J McKenney
- Department of Molecular and Cellular Biology, UC Davis, Davis, California, USA
| | - Kyoko Okada
- Department of Molecular and Cellular Biology, UC Davis, Davis, California, USA
| | - Saad El Riati
- Southern District, Clalit Health Services, Beer-Sheva, Israel
| | - Iris Har-Vardi
- The Center of Advanced Research and Education in Reproduction (CARER), Ben-Gurion University of the Negev Faculty of Health Sciences, Beer-Sheva, Israel.,Fertility and IVF Unit, Department of Obstetrics and Gynecology, Soroka University Medical Center, Beer-Sheva, Israel
| | - Mahmoud Huleihel
- Shraga Segal Department of Microbiology, Immunology and Genetics, Ben-Gurion University of the Negev Faculty of Health Sciences, Beer-Sheva, Israel.,The Center of Advanced Research and Education in Reproduction (CARER), Ben-Gurion University of the Negev Faculty of Health Sciences, Beer-Sheva, Israel
| | - Eliahu Levitas
- The Center of Advanced Research and Education in Reproduction (CARER), Ben-Gurion University of the Negev Faculty of Health Sciences, Beer-Sheva, Israel.,Fertility and IVF Unit, Department of Obstetrics and Gynecology, Soroka University Medical Center, Beer-Sheva, Israel
| | - Ohad S Birk
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel .,Genetics Institute, Soroka University Medical Center, Beer-Sheva, Israel
| | - Uri Abdu
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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5
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Heldrich J, Sun X, Vale-Silva LA, Markowitz TE, Hochwagen A. Topoisomerases Modulate the Timing of Meiotic DNA Breakage and Chromosome Morphogenesis in Saccharomyces cerevisiae. Genetics 2020; 215:59-73. [PMID: 32152049 PMCID: PMC7198267 DOI: 10.1534/genetics.120.303060] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 03/05/2020] [Indexed: 12/12/2022] Open
Abstract
During meiotic prophase, concurrent transcription, recombination, and chromosome synapsis place substantial topological strain on chromosomal DNA, but the role of topoisomerases in this context remains poorly defined. Here, we analyzed the roles of topoisomerases I and II (Top1 and Top2) during meiotic prophase in Saccharomyces cerevisiae We show that both topoisomerases accumulate primarily in promoter-containing intergenic regions of actively transcribing genes, including many meiotic double-strand break (DSB) hotspots. Despite the comparable binding patterns, top1 and top2 mutations have different effects on meiotic recombination. TOP1 disruption delays DSB induction and shortens the window of DSB accumulation by an unknown mechanism. By contrast, temperature-sensitive top2-1 mutants exhibit a marked delay in meiotic chromosome remodeling and elevated DSB signals on synapsed chromosomes. The problems in chromosome remodeling were linked to altered Top2 binding patterns rather than a loss of Top2 catalytic activity, and stemmed from a defect in recruiting the chromosome remodeler Pch2/TRIP13 to synapsed chromosomes. No chromosomal defects were observed in the absence of TOP1 Our results imply independent roles for Top1 and Top2 in modulating meiotic chromosome structure and recombination.
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Affiliation(s)
- Jonna Heldrich
- Department of Biology, New York University, New York 10003
| | - Xiaoji Sun
- Department of Biology, New York University, New York 10003
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6
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Identification of Suppressors of top-2 Embryonic Lethality in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2020; 10:1183-1191. [PMID: 32086248 PMCID: PMC7144083 DOI: 10.1534/g3.119.400927] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Topoisomerase II is an enzyme with important roles in chromosome biology. This enzyme relieves supercoiling and DNA and RNA entanglements generated during mitosis. Recent studies have demonstrated that Topoisomerase II is also involved in the segregation of homologous chromosomes during the first meiotic division. However, the function and regulation of Topoisomerase II in meiosis has not been fully elucidated. Here, we conducted a genetic suppressor screen in Caenorhabditis elegans to identify putative genes that interact with topoisomerase II during meiosis. Using a temperature-sensitive allele of topoisomerase II, top-2(it7ts), we identified eleven suppressors of top-2-induced embryonic lethality. We used whole-genome sequencing and a combination of RNAi and CRISPR/Cas9 genome editing to identify and validate the responsible suppressor mutations. We found both recessive and dominant suppressing mutations that include one intragenic and 10 extragenic loci. The extragenic suppressors consist of a known Topoisomerase II-interacting protein and two novel interactors. We anticipate that further analysis of these suppressing mutations will provide new insights into the function of Topoisomerase II during meiosis.
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7
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Palumbo V, Tariq A, Borgal L, Metz J, Brancaccio M, Gatti M, Wakefield JG, Bonaccorsi S. Drosophila Morgana is an Hsp90-interacting protein with a direct role in microtubule polymerisation. J Cell Sci 2020; 133:jcs236786. [PMID: 31907206 PMCID: PMC6983718 DOI: 10.1242/jcs.236786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 12/17/2019] [Indexed: 12/25/2022] Open
Abstract
Morgana (Mora, also known as CHORD in flies) and its mammalian homologue, called CHORDC1 or CHP1, is a highly conserved cysteine and histidine-rich domain (CHORD)-containing protein that has been proposed to function as an Hsp90 co-chaperone. Morgana deregulation promotes carcinogenesis in both mice and humans while, in Drosophila, loss of mora causes lethality and a complex mitotic phenotype that is rescued by a human morgana transgene. Here, we show that Drosophila Mora localises to mitotic spindles and co-purifies with the Hsp90-R2TP-TTT supercomplex and with additional well-known Hsp90 co-chaperones. Acute inhibition of Mora function in the early embryo results in a dramatic reduction in centrosomal microtubule stability, leading to small spindles nucleated from mitotic chromatin. Purified Mora binds to microtubules directly and promotes microtubule polymerisation in vitro, suggesting that Mora directly regulates spindle dynamics independently of its Hsp90 co-chaperone role.
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Affiliation(s)
- Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie Sapienza, Università di Roma, 00185 Rome, Italy
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Ammarah Tariq
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Lori Borgal
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Jeremy Metz
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Mara Brancaccio
- Dipartimento di Genetica, Biologia e Biochimica, Università di Torino, 10126 Torino, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie Sapienza, Università di Roma, 00185 Rome, Italy
- Istituto di Biologia e Patologia Molecolari del CNR, 00185 Rome, Italy
| | - James G Wakefield
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Silvia Bonaccorsi
- Dipartimento di Biologia e Biotecnologie Sapienza, Università di Roma, 00185 Rome, Italy
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8
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Dokshin GA, Davis GM, Sawle AD, Eldridge MD, Nicholls PK, Gourley TE, Romer KA, Molesworth LW, Tatnell HR, Ozturk AR, de Rooij DG, Hannon GJ, Page DC, Mello CC, Carmell MA. GCNA Interacts with Spartan and Topoisomerase II to Regulate Genome Stability. Dev Cell 2020; 52:53-68.e6. [PMID: 31839538 PMCID: PMC7227305 DOI: 10.1016/j.devcel.2019.11.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 08/14/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022]
Abstract
GCNA proteins are expressed across eukarya in pluripotent cells and have conserved functions in fertility. GCNA homologs Spartan (DVC-1) and Wss1 resolve DNA-protein crosslinks (DPCs), including Topoisomerase-DNA adducts, during DNA replication. Here, we show that GCNA mutants in mouse and C. elegans display defects in genome maintenance including DNA damage, aberrant chromosome condensation, and crossover defects in mouse spermatocytes and spontaneous genomic rearrangements in C. elegans. We show that GCNA and topoisomerase II (TOP2) physically interact in both mice and worms and colocalize on condensed chromosomes during mitosis in C. elegans embryos. Moreover, C. elegans gcna-1 mutants are hypersensitive to TOP2 poison. Together, our findings support a model in which GCNA provides genome maintenance functions in the germline and may do so, in part, by promoting the resolution of TOP2 DPCs.
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Affiliation(s)
- Gregoriy A Dokshin
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Gregory M Davis
- School of Health and Life Sciences, Federation University, VIC 3841, Australia
| | - Ashley D Sawle
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK
| | - Matthew D Eldridge
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK
| | | | - Taylin E Gourley
- School of Health and Life Sciences, Federation University, VIC 3841, Australia
| | - Katherine A Romer
- Whitehead Institute, 455 Main Street, Cambridge, MA 02142, USA; Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Luke W Molesworth
- School of Health and Life Sciences, Federation University, VIC 3841, Australia
| | - Hannah R Tatnell
- School of Health and Life Sciences, Federation University, VIC 3841, Australia
| | - Ahmet R Ozturk
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Dirk G de Rooij
- Whitehead Institute, 455 Main Street, Cambridge, MA 02142, USA; Reproductive Biology Group, Division of Developmental Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584, the Netherlands; Center for Reproductive Medicine, Academic Medical Center, University of Amsterdam 1105, the Netherlands
| | - Gregory J Hannon
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK; Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - David C Page
- Whitehead Institute, 455 Main Street, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Whitehead Institute, Cambridge, MA 02142, USA
| | - Craig C Mello
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Michelle A Carmell
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Whitehead Institute, 455 Main Street, Cambridge, MA 02142, USA; Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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9
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Roles of Topoisomerases in Heterochromatin, Aging, and Diseases. Genes (Basel) 2019; 10:genes10110884. [PMID: 31683993 PMCID: PMC6896002 DOI: 10.3390/genes10110884] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/23/2019] [Accepted: 10/26/2019] [Indexed: 12/11/2022] Open
Abstract
Heterochromatin is a transcriptionally repressive chromatin architecture that has a low abundance of genes but an enrichment of transposons. Defects in heterochromatin can cause the de-repression of genes and transposons, leading to deleterious physiological changes such as aging, cancer, and neurological disorders. While the roles of topoisomerases in many DNA-based processes have been investigated and reviewed, their roles in heterochromatin formation and function are only beginning to be understood. In this review, we discuss recent findings on how topoisomerases can promote heterochromatin organization and impact the transcription of genes and transposons. We will focus on two topoisomerases: Top2α, which catenates and decatenates double-stranded DNA, and Top3β, which can change the topology of not only DNA, but also RNA. Both enzymes are required for normal heterochromatin formation and function, as the inactivation of either protein by genetic mutations or chemical inhibitors can result in defective heterochromatin formation and the de-silencing of transposons. These defects may contribute to the shortened lifespan and neurological disorders observed in individuals carrying mutations of Top3β. We propose that topological stress may be generated in both DNA and RNA during heterochromatin formation and function, which depend on multiple topoisomerases to resolve.
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10
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A new role for Drosophila Aurora-A in maintaining chromosome integrity. Chromosoma 2019; 128:41-52. [PMID: 30612150 DOI: 10.1007/s00412-018-00687-0] [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: 07/16/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 02/07/2023]
Abstract
Aurora-A is a conserved mitotic kinase overexpressed in many types of cancer. Growing evidence shows that Aurora-A plays a crucial role in DNA damage response (DDR) although this aspect has been less characterized. We isolated a new aur-A mutation, named aur-A949, in Drosophila, and we showed that it causes chromosome aberrations (CABs). In addition, aur-A949 mutants were sensitive to X-ray treatment and showed impaired γ-H2Av foci dissolution kinetics. To identify the pathway in which Aur-A works, we conducted an epistasis analysis by evaluating CAB frequencies in double mutants carrying aur-A949 mutation combined to mutations in genes related to DNA damage response (DDR). We found that mutations in tefu (ATM) and in the histone variant H2Av were epistatic over aur-A949 indicating that Aur-A works in DDR and that it is required for γ-H2Av foci dissolution. More interestingly, we found that a mutation in lig4, a gene belonging to the non-homologous end joining (NHEJ) repair pathway, was epistatic over aur-A949. Based on studies in other systems, which show that phosphorylation is important to target Lig4 for degradation, we hypothesized that in aur-A949 mutant cells, there is a persistence of Lig4 that could be, in the end, responsible for CABs. Finally, we observed a synergistic interaction between Aur-A and the homologous recombination (HR) repair system component Rad 51 in the process that converts chromatid deletions into isochromatid deletions. Altogether, these data indicate that Aur-A depletion can elicit chromosome damage. This conclusion should be taken into consideration, since some anticancer therapies are aimed at reducing Aurora-A expression.
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11
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Merigliano C, Mascolo E, Burla R, Saggio I, Vernì F. The Relationship Between Vitamin B6, Diabetes and Cancer. Front Genet 2018; 9:388. [PMID: 30271425 PMCID: PMC6146109 DOI: 10.3389/fgene.2018.00388] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 08/29/2018] [Indexed: 11/15/2022] Open
Abstract
Pyridoxal 5′-phosphate (PLP), the active form of vitamin B6, works as cofactor in numerous enzymatic reactions and it behaves as antioxidant molecule. PLP deficiency has been associated to many human pathologies including cancer and diabetes and the mechanism behind this connection is now becoming clearer. Inadequate intake of this vitamin increases the risk of many cancers; furthermore, PLP deprivation impairs insulin secretion in rats, whereas PLP supplementation prevents diabetic complications and improves gestational diabetes. Growing evidence shows that diabetes and cancer are correlated not only because they share same risk factors but also because diabetic patients have a higher risk of developing tumors, although the underlying mechanisms remain elusive. In this review, we will explore data obtained in Drosophila revealing the existence of a connection between vitamin B6, DNA damage and diabetes, as flies in the past decade turned out to be a promising model also for metabolic diseases including diabetes. We will focus on recent studies that revealed a specific role for PLP in maintaining chromosome integrity and glucose homeostasis, and we will show that these aspects are correlated. In addition, we will discuss recent data identifying PLP as a putative linking factor between diabetes and cancer.
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Affiliation(s)
- Chiara Merigliano
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma, Rome, Italy
| | - Elisa Mascolo
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma, Rome, Italy
| | - Romina Burla
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma, Rome, Italy
| | - Isabella Saggio
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma, Rome, Italy.,Institute of Structural Biology, School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Fiammetta Vernì
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma, Rome, Italy
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12
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Graziadio L, Palumbo V, Cipressa F, Williams BC, Cenci G, Gatti M, Goldberg ML, Bonaccorsi S. Phenotypic characterization of diamond (dind), a Drosophila gene required for multiple aspects of cell division. Chromosoma 2018; 127:489-504. [PMID: 30120539 DOI: 10.1007/s00412-018-0680-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 01/04/2023]
Abstract
Many genes are required for the assembly of the mitotic apparatus and for proper chromosome behavior during mitosis and meiosis. A fruitful approach to elucidate the mechanisms underlying cell division is the accurate phenotypic characterization of mutations in these genes. Here, we report the identification and characterization of diamond (dind), an essential Drosophila gene required both for mitosis of larval brain cells and for male meiosis. Larvae homozygous for any of the five EMS-induced mutations die in the third-instar stage and exhibit multiple mitotic defects. Mutant brain cells exhibit poorly condensed chromosomes and frequent chromosome breaks and rearrangements; they also show centriole fragmentation, disorganized mitotic spindles, defective chromosome segregation, endoreduplicated metaphases, and hyperploid and polyploid cells. Comparable phenotypes occur in mutant spermatogonia and spermatocytes. The dind gene encodes a non-conserved protein with no known functional motifs. Although the Dind protein exhibits a rather diffuse localization in both interphase and mitotic cells, fractionation experiments indicate that some Dind is tightly associated with the chromatin. Collectively, these results suggest that loss of Dind affects chromatin organization leading to defects in chromosome condensation and integrity, which in turn affect centriole stability and spindle assembly. However, our results do not exclude the possibility that Dind directly affects some behaviors of the spindle and centrosomes.
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Affiliation(s)
- Lucia Graziadio
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy
| | - Francesca Cipressa
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.,Museo storico della fisica e centro di studi e ricerche Enrico Fermi, Rome, Italy
| | - Byron C Williams
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.,Istituto Pasteur Fondazione Cenci Bolognetti, Rome, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.,Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
| | - Michael L Goldberg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
| | - Silvia Bonaccorsi
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.
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13
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Piskadlo E, Oliveira RA. A Topology-Centric View on Mitotic Chromosome Architecture. Int J Mol Sci 2017; 18:E2751. [PMID: 29258269 PMCID: PMC5751350 DOI: 10.3390/ijms18122751] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 02/04/2023] Open
Abstract
Mitotic chromosomes are long-known structures, but their internal organization and the exact process by which they are assembled are still a great mystery in biology. Topoisomerase II is crucial for various aspects of mitotic chromosome organization. The unique ability of this enzyme to untangle topologically intertwined DNA molecules (catenations) is of utmost importance for the resolution of sister chromatid intertwines. Although still controversial, topoisomerase II has also been proposed to directly contribute to chromosome compaction, possibly by promoting chromosome self-entanglements. These two functions raise a strong directionality issue towards topoisomerase II reactions that are able to disentangle sister DNA molecules (in trans) while compacting the same DNA molecule (in cis). Here, we review the current knowledge on topoisomerase II role specifically during mitosis, and the mechanisms that directly or indirectly regulate its activity to ensure faithful chromosome segregation. In particular, we discuss how the activity or directionality of this enzyme could be regulated by the SMC (structural maintenance of chromosomes) complexes, predominantly cohesin and condensin, throughout mitosis.
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Affiliation(s)
- Ewa Piskadlo
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal.
| | - Raquel A Oliveira
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal.
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14
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Bianchi FT, Tocco C, Pallavicini G, Liu Y, Vernì F, Merigliano C, Bonaccorsi S, El-Assawy N, Priano L, Gai M, Berto GE, Chiotto AMA, Sgrò F, Caramello A, Tasca L, Ala U, Neri F, Oliviero S, Mauro A, Geley S, Gatti M, Di Cunto F. Citron Kinase Deficiency Leads to Chromosomal Instability and TP53-Sensitive Microcephaly. Cell Rep 2017; 18:1674-1686. [PMID: 28199840 PMCID: PMC5318669 DOI: 10.1016/j.celrep.2017.01.054] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 12/16/2016] [Accepted: 01/22/2017] [Indexed: 11/16/2022] Open
Abstract
Mutations in citron (CIT), leading to loss or inactivation of the citron kinase protein (CITK), cause primary microcephaly in humans and rodents, associated with cytokinesis failure and apoptosis in neural progenitors. We show that CITK loss induces DNA damage accumulation and chromosomal instability in both mammals and Drosophila. CITK-deficient cells display "spontaneous" DNA damage, increased sensitivity to ionizing radiation, and defective recovery from radiation-induced DNA lesions. In CITK-deficient cells, DNA double-strand breaks increase independently of cytokinesis failure. Recruitment of RAD51 to DNA damage foci is compromised by CITK loss, and CITK physically interacts with RAD51, suggesting an involvement of CITK in homologous recombination. Consistent with this scenario, in doubly CitK and Trp53 mutant mice, neural progenitor cell death is dramatically reduced; moreover, clinical and neuroanatomical phenotypes are remarkably improved. Our results underscore a crucial role of CIT in the maintenance of genomic integrity during brain development.
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Affiliation(s)
- Federico Tommaso Bianchi
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of Turin, 10043 Orbassano (TO), Italy.
| | - Chiara Tocco
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Gianmarco Pallavicini
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of Turin, 10043 Orbassano (TO), Italy
| | - Yifan Liu
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Fiammetta Vernì
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University, 00185 Rome, Italy
| | - Chiara Merigliano
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University, 00185 Rome, Italy
| | - Silvia Bonaccorsi
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University, 00185 Rome, Italy
| | - Nadia El-Assawy
- Department of Neurology and Neurorehabilitation, San Giuseppe Hospital, Istituto Auxologico Italiano IRCCS, 28824 Piancavallo (VB), Italy
| | - Lorenzo Priano
- Department of Neurology and Neurorehabilitation, San Giuseppe Hospital, Istituto Auxologico Italiano IRCCS, 28824 Piancavallo (VB), Italy; Department of Neuroscience, University of Torino, 10126 Torino, Italy
| | - Marta Gai
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Gaia Elena Berto
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of Turin, 10043 Orbassano (TO), Italy
| | - Alessandra Maria Adelaide Chiotto
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of Turin, 10043 Orbassano (TO), Italy
| | - Francesco Sgrò
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Alessia Caramello
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Laura Tasca
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of Turin, 10043 Orbassano (TO), Italy
| | - Ugo Ala
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Francesco Neri
- Human Genetics Foundation (HuGeF), via Nizza 52, 10126 Torino, Italy
| | | | - Alessandro Mauro
- Department of Neurology and Neurorehabilitation, San Giuseppe Hospital, Istituto Auxologico Italiano IRCCS, 28824 Piancavallo (VB), Italy; Department of Neuroscience, University of Torino, 10126 Torino, Italy
| | - Stephan Geley
- Division of Molecular Pathophysiology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Maurizio Gatti
- Department of Biology and Biotechnology "Charles Darwin," Sapienza University, 00185 Rome, Italy; Institute of Molecular Biology and Pathology (IBPM), CNR, 00185 Rome, Italy
| | - Ferdinando Di Cunto
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy; Neuroscience Institute Cavalieri Ottolenghi, University of Turin, 10043 Orbassano (TO), Italy.
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15
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The Hybrid Incompatibility Genes Lhr and Hmr Are Required for Sister Chromatid Detachment During Anaphase but Not for Centromere Function. Genetics 2017; 207:1457-1472. [PMID: 29046402 DOI: 10.1534/genetics.117.300390] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/13/2017] [Indexed: 11/18/2022] Open
Abstract
Crosses between Drosophila melanogaster females and Drosophila simulans males produce hybrid sons that die at the larval stage. This hybrid lethality is suppressed by loss-of-function mutations in the D. melanogaster Hybrid male rescue (Hmr) or in the D. simulans Lethal hybrid rescue (Lhr) genes. Previous studies have shown that Hmr and Lhr interact with heterochromatin proteins and suppress expression of transposable elements within D. melanogaster It also has been proposed that Hmr and Lhr function at the centromere. We examined mitotic divisions in larval brains from Hmr and Lhr single mutants and Hmr; Lhr double mutants in D. melanogaster In none of the mutants did we observe defects in metaphase chromosome alignment or hyperploid cells, which are hallmarks of centromere or kinetochore dysfunction. In addition, we found that Hmr-HA and Lhr-HA do not colocalize with centromeres either during interphase or mitotic division. However, all mutants displayed anaphase bridges and chromosome aberrations resulting from the breakage of these bridges, predominantly at the euchromatin-heterochromatin junction. The few dividing cells present in hybrid males showed fuzzy and irregularly condensed chromosomes with unresolved sister chromatids. Despite this defect in condensation, chromosomes in hybrids managed to align on the metaphase plate and undergo anaphase. We conclude that there is no evidence for a centromeric function of Hmr and Lhr within D. melanogaster nor for a centromere defect causing hybrid lethality. Instead, we find that Hmr and Lhr are required in D. melanogaster for detachment of sister chromatids during anaphase.
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16
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Tang X, Cao J, Zhang L, Huang Y, Zhang Q, Rong YS. Maternal Haploid, a Metalloprotease Enriched at the Largest Satellite Repeat and Essential for Genome Integrity in Drosophila Embryos. Genetics 2017; 206:1829-1839. [PMID: 28615282 PMCID: PMC5560791 DOI: 10.1534/genetics.117.200949] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/30/2017] [Indexed: 01/03/2023] Open
Abstract
The incorporation of the paternal genome into the zygote during fertilization requires chromatin remodeling. The maternal haploid (mh) mutation in Drosophila affects this process and leads to the formation of haploid embryos without the paternal genome. mh encodes the Drosophila homolog of SPRTN, a conserved protease essential for resolving DNA-protein cross-linked products. Here we characterize the role of MH in genome maintenance. It is not understood how MH protects the paternal genome during fertilization, particularly in light of our finding that MH is present in both parental pronuclei during zygote formation. We showed that maternal chromosomes in mh mutant embryos experience instabilities in the absence of the paternal genome, which suggests that MH is generally required for chromosome stability during embryogenesis. This is consistent with our finding that MH is abundantly present on chromatin throughout the cell cycle. Remarkably, MH is prominently enriched at the 359-bp satellite repeats during interphase, which becomes unstable without MH. This dynamic localization and specific enrichment of MH at the 359 repeats resemble that of Topoisomerase 2 (Top2), suggesting that MH regulates Top2, possibly as a protease for the resolution of Top2-DNA intermediates. We propose that maternal MH removes proteins specifically enriched on sperm chromatin. In the absence of that function, paternal chromosomes are precipitously lost. This mode of paternal chromatin remodeling is likely conserved and the unique phenotype of the Drosophila mh mutants represents a rare opportunity to gain insights into the process that has been difficult to study.
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Affiliation(s)
- Xiaona Tang
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892
| | - Jinguo Cao
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892
- Department of Medicine, Jinggangshan University, Ji'an, 343009, China
| | - Liang Zhang
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892
| | - Yingzi Huang
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892
| | - Qianyi Zhang
- State Key Laboratory of Bio-control, Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Yikang S Rong
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892
- State Key Laboratory of Bio-control, Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
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17
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Merigliano C, Marzio A, Renda F, Somma MP, Gatti M, Vernì F. A Role for the Twins Protein Phosphatase (PP2A-B55) in the Maintenance of Drosophila Genome Integrity. Genetics 2017; 205:1151-1167. [PMID: 28040742 PMCID: PMC5340330 DOI: 10.1534/genetics.116.192781] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/21/2016] [Indexed: 01/14/2023] Open
Abstract
The protein phosphatase 2A (PP2A) is a conserved heterotrimeric enzyme that regulates several cellular processes including the DNA damage response and mitosis. Consistent with these functions, PP2A is mutated in many types of cancer and acts as a tumor suppressor. In mammalian cells, PP2A inhibition results in DNA double strand breaks (DSBs) and chromosome aberrations (CABs). However, the mechanisms through which PP2A prevents DNA damage are still unclear. Here, we focus on the role of the Drosophila twins (tws) gene in the maintenance of chromosome integrity; tws encodes the B regulatory subunit (B/B55) of PP2A. Mutations in tws cause high frequencies of CABs (0.5 CABs/cell) in Drosophila larval brain cells and lead to an abnormal persistence of γ-H2Av repair foci. However, mutations that disrupt the PP4 phosphatase activity impair foci dissolution but do not cause CABs, suggesting that a delayed foci regression is not clastogenic. We also show that Tws is required for activation of the G2/M DNA damage checkpoint while PP4 is required for checkpoint recovery, a result that points to a conserved function of these phosphatases from flies to humans. Mutations in the ATM-coding gene tefu are strictly epistatic to tws mutations for the CAB phenotype, suggesting that failure to dephosphorylate an ATM substrate(s) impairs DNA DSBs repair. In addition, mutations in the Ku70 gene, which do not cause CABs, completely suppress CAB formation in tws Ku70 double mutants. These results suggest the hypothesis that an improperly phosphorylated Ku70 protein can lead to DNA damage and CABs.
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Affiliation(s)
- Chiara Merigliano
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza, Università di Roma, 00185, Italy
| | - Antonio Marzio
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza, Università di Roma, 00185, Italy
| | - Fioranna Renda
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza, Università di Roma, 00185, Italy
| | - Maria Patrizia Somma
- Istituto di Biologia e Patologia Molecolari del Consiglio Nazionale delle Ricerche, Sapienza, Università di Roma, 00185, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza, Università di Roma, 00185, Italy
- Istituto di Biologia e Patologia Molecolari del Consiglio Nazionale delle Ricerche, Sapienza, Università di Roma, 00185, Italy
| | - Fiammetta Vernì
- Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza, Università di Roma, 00185, Italy
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18
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Jaramillo-Lambert A, Fabritius AS, Hansen TJ, Smith HE, Golden A. The Identification of a Novel Mutant Allele of topoisomerase II in Caenorhabditis elegans Reveals a Unique Role in Chromosome Segregation During Spermatogenesis. Genetics 2016; 204:1407-1422. [PMID: 27707787 PMCID: PMC5161275 DOI: 10.1534/genetics.116.195099] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 09/30/2016] [Indexed: 01/03/2023] Open
Abstract
Topoisomerase II alleviates DNA entanglements that are generated during mitotic DNA replication, transcription, and sister chromatid separation. In contrast to mitosis, meiosis has two rounds of chromosome segregation following one round of DNA replication. In meiosis II, sister chromatids segregate from each other, similar to mitosis. Meiosis I, on the other hand, segregates homologs, which requires pairing, synapsis, and recombination. The exact role that topoisomerase II plays during meiosis is unknown. In a screen reexamining Caenorhabditis elegans legacy mutants isolated 30 years ago, we identified a novel allele of the gene encoding topoisomerase II, top-2(it7). In this study, we demonstrate that top-2(it7) males produce dead embryos, even when fertilizing wild-type oocytes. Characterization of early embryonic events indicates that fertilization is successful and sperm components are transmitted to the embryo. However, sperm chromatin is not detected in these fertilized embryos. Examination of top-2(it7) spermatogenic germ lines reveals that the sperm DNA fails to segregate properly during anaphase I of meiosis, resulting in anucleate sperm. top-2(it7) chromosome-segregation defects observed during anaphase I are not due to residual entanglements incurred during meiotic DNA replication and are not dependent on SPO-11-induced double-strand DNA breaks. Finally, we show that TOP-2 associates with chromosomes in meiotic prophase and that chromosome association is disrupted in the germ lines of top-2(it7) mutants.
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Affiliation(s)
- Aimee Jaramillo-Lambert
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Amy S Fabritius
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Tyler J Hansen
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Harold E Smith
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Andy Golden
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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