1
|
Klushevskaya ES, Alembekov IR, Kravatsky YV, Tchurikov NA. Homeotic DUX4 Genes Shape Dynamic Inter-Chromosomal Contacts with Nucleoli in Human Cells. DOKL BIOCHEM BIOPHYS 2024:10.1134/S1607672924700935. [PMID: 39002012 DOI: 10.1134/s1607672924700935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 07/15/2024]
Abstract
Nucleoli form interchromosomal contacts with genes controlling differentiation and carcinogenesis. DUX4 genes specify transcription factor possessing two homeodomains. Previously, using Circular Chromosome Conformation Capture (4С) approach on population of cells, it was demonstrated that DUX4 gene clusters form frequent contacts with nucleoli. It was found also that these contacts are almost completely abolished after heat shock treatment. 4C approach as all ligation-mediated methods is capable to detect rather close interactions between chromatin loops in nuclei. In order to independently confirm the formation and the frequency of the contacts in single cells we used FISH approach. Here, we show that DUX genes in single cells form stable contacts in all tested HEK293T cells. During heat shock, DUX4 genes reversibly move 1-3 µm away from the nuclei. We conclude that interchromosomal contacts formed by nucleoli are strong, dynamic, and reversible, providing both the initiation and maintenance of a differentiated state.
Collapse
Affiliation(s)
- E S Klushevskaya
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
| | - I R Alembekov
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
| | - Y V Kravatsky
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
| | - N A Tchurikov
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia.
| |
Collapse
|
2
|
Amoiridis M, Verigos J, Meaburn K, Gittens WH, Ye T, Neale MJ, Soutoglou E. Inhibition of topoisomerase 2 catalytic activity impacts the integrity of heterochromatin and repetitive DNA and leads to interlinks between clustered repeats. Nat Commun 2024; 15:5727. [PMID: 38977669 PMCID: PMC11231352 DOI: 10.1038/s41467-024-49816-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 06/14/2024] [Indexed: 07/10/2024] Open
Abstract
DNA replication and transcription generate DNA supercoiling, which can cause topological stress and intertwining of daughter chromatin fibers, posing challenges to the completion of DNA replication and chromosome segregation. Type II topoisomerases (Top2s) are enzymes that relieve DNA supercoiling and decatenate braided sister chromatids. How Top2 complexes deal with the topological challenges in different chromatin contexts, and whether all chromosomal contexts are subjected equally to torsional stress and require Top2 activity is unknown. Here we show that catalytic inhibition of the Top2 complex in interphase has a profound effect on the stability of heterochromatin and repetitive DNA elements. Mechanistically, we find that catalytically inactive Top2 is trapped around heterochromatin leading to DNA breaks and unresolved catenates, which necessitate the recruitment of the structure specific endonuclease, Ercc1-XPF, in an SLX4- and SUMO-dependent manner. Our data are consistent with a model in which Top2 complex resolves not only catenates between sister chromatids but also inter-chromosomal catenates between clustered repetitive elements.
Collapse
Affiliation(s)
- Michalis Amoiridis
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France
- Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - John Verigos
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
| | - Karen Meaburn
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
| | - William H Gittens
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
| | - Tao Ye
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France
- Centre National de Recherche Scientifique (CNRS), UMR7104, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Matthew J Neale
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK
| | - Evi Soutoglou
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RH, UK.
| |
Collapse
|
3
|
Agabekian IA, Abdulkina LR, Lushnenko AY, Young PG, Valeeva LR, Boskovic O, Lilly EG, Sharipova MR, Shippen DE, Juenger TE, Shakirov EV. Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control. PLANT MOLECULAR BIOLOGY 2024; 114:65. [PMID: 38816532 DOI: 10.1007/s11103-024-01457-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/23/2024] [Indexed: 06/01/2024]
Abstract
Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a -deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.
Collapse
Affiliation(s)
- Inna A Agabekian
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Liliia R Abdulkina
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Alina Y Lushnenko
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Pierce G Young
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas, 77843-2128, USA
| | - Lia R Valeeva
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Olivia Boskovic
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Ethan G Lilly
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Margarita R Sharipova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas, 77843-2128, USA.
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78712, USA.
| | - Eugene V Shakirov
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA.
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, 25755, USA.
| |
Collapse
|
4
|
Sadler DE, Watts PC, Uusi-Heikkilä S. Directional selection, not the direction of selection, affects telomere length and copy number at ribosomal RNA loci. Sci Rep 2024; 14:12162. [PMID: 38802448 PMCID: PMC11130246 DOI: 10.1038/s41598-024-63030-x] [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: 03/14/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024] Open
Abstract
Many fisheries exert directional selection on traits such as body size and growth rate. Whether directional selection impacts regions of the genome associated with traits related to growth is unknown. To address this issue, we characterised copy number variation in three regions of the genome associated with cell division, (1) telomeric DNA, (2) loci transcribed as ribosomal RNA (rDNA), and (3) mitochondrial DNA (mtDNA), in three selection lines of zebrafish reared at three temperatures (22 °C, 28 °C, and 34 °C). Selection lines differed in (1) the direction of selection (two lines experienced directional selection for large or small body size) and (2) whether they experienced any directional selection itself. Lines that had experienced directional selection were smaller, had lower growth rate, shorter telomeres, and lower rDNA copy number than the line that experiencing no directional selection. Neither telomere length nor rDNA copy number were affected by temperature. In contrast, mtDNA content increased at elevated temperature but did not differ among selection lines. Though directional selection impacts rDNA and telomere length, direction of such selection did not matter, whereas mtDNA acts as a stress marker for temperature. Future work should examine the consequences of these genomic changes in natural fish stocks.
Collapse
Affiliation(s)
- Daniel E Sadler
- Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland.
| | - Phillip C Watts
- Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| | - Silva Uusi-Heikkilä
- Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| |
Collapse
|
5
|
Zhang Y, Hu G, Zhang Q, Hong S, Su Z, Wang L, Wang T, Yu S, Yuan F, Zhu X, Jia G. Cellular senescence mediates hexavalent chromium-associated lung function decline: Insights from a structural equation Model. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 349:123947. [PMID: 38608856 DOI: 10.1016/j.envpol.2024.123947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/14/2024]
Abstract
There is sufficient evidence suggesting that exposure to hexavalent chromium [Cr(VI)] can cause a decline in lung function and the onset of lung diseases. However, no studies have yet explored the underlying mechanisms of these effects from various perspectives such as systemic inflammation, oxidative stress, and cellular senescence, simultaneously. This cross-sectional study was conducted among 304 workers engaged in chromate production and processing in China. Urine was used for detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F2α (8-iso-PGF2α), while RNA and DNA extraction from peripheral blood cells was used for detection of mRNA, telomere length, and ribosomal DNA copy numbers (rDNA CNs). A 2.7-fold elevation in blood chromate (Cr) corresponded to a 7.86% (95% CI: 2.57%, 13.42%) rise in urinary 8-OHdG and a 4.14% (0.02%, 8.42%) increase in urinary 8-iso-PGF2α, indicating that exposure to chromates can cause oxidative stress. Furthermore, strong correlations emerged between blood Cr concentration and mRNA levels of P16, P21, TP53, and P15 in the cellular senescence pathway. Simultaneously, a 2.7-fold elevation in blood Cr associated with a -5.47% (-8.72%, -2.1%) change in telomere length, while rDNA CNs (5S, 5.8S, 18S, and 28S) changed by -3.91% (-7.99%, 0.34%), -9.4% (-15.73%, -2.6%), -8.06% (-14.01%, -1.69%), and -5.86% (-10.67%, -0.78%), respectively. Structural equation model highlighted that cellular senescence exerted significant indirect effects on Cr(VI)-associated lung function decline, with a mediation proportion of 23.3%. This study provided data supporting for 8-iso-PGF2α, telomere length, and rDNA CNs as novel biomarkers of chromate exposure, emphasizing the significant role of cellular senescence in the mechanism underlying chromate-induced lung function decline.
Collapse
Affiliation(s)
- Yali Zhang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, School of Public Health, Peking University, Beijing 100191, China
| | - Guiping Hu
- School of Engineering Medicine and Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University, Beijing 100191, China
| | - Qiaojian Zhang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, School of Public Health, Peking University, Beijing 100191, China
| | - Shiyi Hong
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, School of Public Health, Peking University, Beijing 100191, China
| | - Zekang Su
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, School of Public Health, Peking University, Beijing 100191, China
| | - Li Wang
- Department of Occupational and Environmental Health Science, Baotou Medical College, Baotou, Inner Mongolia 014030, China
| | - Tiancheng Wang
- Department of Clinical Laboratory, Third Hospital of Peking University, Beijing 100191, China
| | - Shanfa Yu
- Henan Institute for Occupational Medicine, Zhengzhou City, Henan Province 450052, China
| | - Fang Yuan
- Department of Occupational Health and Radiological Health, Chongqing Center for Disease Control and Prevention, Chongqing 400042, China
| | - Xiaojun Zhu
- National Center for Occupational Safety and Health, Beijing 102308, China
| | - Guang Jia
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, School of Public Health, Peking University, Beijing 100191, China.
| |
Collapse
|
6
|
Wu C, Tu T, Xie M, Wang Y, Yan B, Gong Y, Zhang J, Zhou X, Xie Z. Spatially resolved transcriptome of the aging mouse brain. Aging Cell 2024; 23:e14109. [PMID: 38372175 PMCID: PMC11113349 DOI: 10.1111/acel.14109] [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: 09/28/2023] [Revised: 01/22/2024] [Accepted: 01/29/2024] [Indexed: 02/20/2024] Open
Abstract
Brain aging is associated with cognitive decline, memory loss and many neurodegenerative disorders. The mammalian brain has distinct structural regions that perform specific functions. However, our understanding in gene expression and cell types within the context of the spatial organization of the mammalian aging brain is limited. Here we generated spatial transcriptomic maps of young and old mouse brains. We identified 27 distinguished brain spatial domains, including layer-specific subregions that are difficult to dissect individually. We comprehensively characterized spatial-specific changes in gene expression in the aging brain, particularly for isocortex, the hippocampal formation, brainstem and fiber tracts, and validated some gene expression differences by qPCR and immunohistochemistry. We identified aging-related genes and pathways that vary in a coordinated manner across spatial regions and parsed the spatial features of aging-related signals, providing important clues to understand genes with specific functions in different brain regions during aging. Combined with single-cell transcriptomics data, we characterized the spatial distribution of brain cell types. The proportion of immature neurons decreased in the DG region with aging, indicating that the formation of new neurons is blocked. Finally, we detected changes in information interactions between regions and found specific pathways were deregulated with aging, including classic signaling WNT and layer-specific signaling COLLAGEN. In summary, we established a spatial molecular atlas of the aging mouse brain (http://sysbio.gzzoc.com/Mouse-Brain-Aging/), which provides important resources and novel insights into the molecular mechanism of brain aging.
Collapse
Affiliation(s)
- Cheng Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat‐sen UniversityGuangzhouChina
| | - Tianxiang Tu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat‐sen UniversityGuangzhouChina
| | - Mingzhe Xie
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat‐sen UniversityGuangzhouChina
| | - Yiting Wang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, MOE Innovative Center for New Drug Development of Immune Inflammatory DiseasesInstitutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan UniversityShanghaiChina
| | - Biao Yan
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, MOE Innovative Center for New Drug Development of Immune Inflammatory DiseasesInstitutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan UniversityShanghaiChina
| | - Yajun Gong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat‐sen UniversityGuangzhouChina
| | - Jiayi Zhang
- State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, MOE Innovative Center for New Drug Development of Immune Inflammatory DiseasesInstitutes of Brain Science, Institute for Medical and Engineering Innovation, Department of Ophthalmology, Eye & ENT Hospital, Fudan UniversityShanghaiChina
| | - Xiaolai Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat‐sen UniversityGuangzhouChina
| | - Zhi Xie
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic CenterSun Yat‐sen UniversityGuangzhouChina
| |
Collapse
|
7
|
Watase GJ, Yamashita YM. RNA polymerase II-mediated rDNA transcription mediates rDNA copy number expansion in Drosophila. PLoS Genet 2024; 20:e1011136. [PMID: 38758955 PMCID: PMC11139327 DOI: 10.1371/journal.pgen.1011136] [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: 01/11/2024] [Revised: 05/30/2024] [Accepted: 05/08/2024] [Indexed: 05/19/2024] Open
Abstract
Ribosomal DNA (rDNA), which encodes ribosomal RNA, is an essential but unstable genomic element due to its tandemly repeated nature. rDNA's repetitive nature causes spontaneous intrachromatid recombination, leading to copy number (CN) reduction, which must be counteracted by a mechanism that recovers CN to sustain cells' viability. Akin to telomere maintenance, rDNA maintenance is particularly important in cell types that proliferate for an extended time period, most notably in the germline that passes the genome through generations. In Drosophila, the process of rDNA CN recovery, known as 'rDNA magnification', has been studied extensively. rDNA magnification is mediated by unequal sister chromatid exchange (USCE), which generates a sister chromatid that gains the rDNA CN by stealing copies from its sister. However, much remains elusive regarding how germ cells sense rDNA CN to decide when to initiate magnification, and how germ cells balance between the need to generate DNA double-strand breaks (DSBs) to trigger USCE vs. avoiding harmful DSBs. Recently, we identified an rDNA-binding Zinc-finger protein Indra as a factor required for rDNA magnification, however, the underlying mechanism of action remains unknown. Here we show that Indra is a negative regulator of rDNA magnification, balancing the need of rDNA magnification and repression of dangerous DSBs. Mechanistically, we show that Indra is a repressor of RNA polymerase II (Pol II)-dependent transcription of rDNA: Under low rDNA CN conditions, Indra protein amount is downregulated, leading to Pol II-mediated transcription of rDNA. This results in the expression of rDNA-specific retrotransposon, R2, which we have shown to facilitate rDNA magnification via generation of DBSs at rDNA. We propose that differential use of Pol I and Pol II plays a critical role in regulating rDNA CN expansion only when it is necessary.
Collapse
Affiliation(s)
- George J. Watase
- Department of Germline Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Chuo-ku, Kumamoto-shi, Kumamoto, JAPAN
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Yukiko M. Yamashita
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
- Howard Hughes Medical Institute, Cambridge, Massachusetts, United States of America
| |
Collapse
|
8
|
Ghimire P, Motamedi M, Joh R. Mathematical model for the role of multiple pericentromeric repeats on heterochromatin assembly. PLoS Comput Biol 2024; 20:e1012027. [PMID: 38598558 PMCID: PMC11034663 DOI: 10.1371/journal.pcbi.1012027] [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: 08/04/2023] [Revised: 04/22/2024] [Accepted: 03/27/2024] [Indexed: 04/12/2024] Open
Abstract
Although the length and constituting sequences for pericentromeric repeats are highly variable across eukaryotes, the presence of multiple pericentromeric repeats is one of the conserved features of the eukaryotic chromosomes. Pericentromeric heterochromatin is often misregulated in human diseases, with the expansion of pericentromeric repeats in human solid cancers. In this article, we have developed a mathematical model of the RNAi-dependent methylation of H3K9 in the pericentromeric region of fission yeast. Our model, which takes copy number as an explicit parameter, predicts that the pericentromere is silenced only if there are many copies of repeats. It becomes bistable or desilenced if the copy number of repeats is reduced. This suggests that the copy number of pericentromeric repeats alone can determine the fate of heterochromatin silencing in fission yeast. Through sensitivity analysis, we identified parameters that favor bistability and desilencing. Stochastic simulation shows that faster cell division and noise favor the desilenced state. These results show the unexpected role of pericentromeric repeat copy number in gene silencing and provide a quantitative basis for how the copy number allows or protects repetitive and unique parts of the genome from heterochromatin silencing, respectively.
Collapse
Affiliation(s)
- Puranjan Ghimire
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Mo Motamedi
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, Boston, Massachusetts, United States of America
| | - Richard Joh
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Massey Cancer Center, Virginia Commonwealth University, Richmond Virginia, United States of America
| |
Collapse
|
9
|
Showman S, Talbert PB, Xu Y, Adeyemi RO, Henikoff S. Expansion of human centromeric arrays in cells undergoing break-induced replication. Cell Rep 2024; 43:113851. [PMID: 38427559 PMCID: PMC11034957 DOI: 10.1016/j.celrep.2024.113851] [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: 11/11/2023] [Revised: 01/10/2024] [Accepted: 02/07/2024] [Indexed: 03/03/2024] Open
Abstract
Human centromeres are located within α-satellite arrays and evolve rapidly, which can lead to individual variation in array length. Proposed mechanisms for such alterations in length are unequal crossover between sister chromatids, gene conversion, and break-induced replication. However, the underlying molecular mechanisms responsible for the massive, complex, and homogeneous organization of centromeric arrays have not been experimentally validated. Here, we use droplet digital PCR assays to demonstrate that centromeric arrays can expand and contract within ∼20 somatic cell divisions of an alternative lengthening of telomere (ALT)-positive cell line. We find that the frequency of array variation among single-cell-derived subclones ranges from a minimum of ∼7% to a maximum of ∼100%. Further clonal evolution revealed that centromere expansion is favored over contraction. We find that the homologous recombination protein RAD52 and the helicase PIF1 are required for extensive array change, suggesting that centromere sequence evolution can occur via break-induced replication.
Collapse
Affiliation(s)
- Soyeon Showman
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Paul B Talbert
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Yiling Xu
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Richard O Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
| |
Collapse
|
10
|
Liang Y, Yuan Q, Zheng Q, Mei Z, Song Y, Yan H, Yang J, Wu S, Yuan J, Wu W. DNA Damage Atlas: an atlas of DNA damage and repair. Nucleic Acids Res 2024; 52:D1218-D1226. [PMID: 37831087 PMCID: PMC10767978 DOI: 10.1093/nar/gkad845] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 09/06/2023] [Accepted: 09/21/2023] [Indexed: 10/14/2023] Open
Abstract
DNA damage and its improper repair are the major source of genomic alterations responsible for many human diseases, particularly cancer. To aid researchers in understanding the underlying mechanisms of genome instability, a number of genome-wide profiling approaches have been developed to monitor DNA damage and repair events. The rapid accumulation of published datasets underscores the critical necessity of a comprehensive database to curate sequencing data on DNA damage and repair intermediates. Here, we present DNA Damage Atlas (DDA, http://www.bioinformaticspa.com/DDA/), the first large-scale repository of DNA damage and repair information. Currently, DDA comprises 6,030 samples from 262 datasets by 59 technologies, covering 16 species, 10 types of damage and 135 treatments. Data collected in DDA was processed through a standardized workflow, including quality checks, hotspots identification and a series of feature characterization for the hotspots. Notably, DDA encompasses analyses of highly repetitive regions, ribosomal DNA and telomere. DDA offers a user-friendly interface that facilitates browsing, searching, genome browser visualization, hotspots comparison and data downloading, enabling convenient and thorough exploration for datasets of interest. In summary, DDA will stand as a valuable resource for research in genome instability and its association with diseases.
Collapse
Affiliation(s)
- Yu Liang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Qingqing Yuan
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Qijie Zheng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Zilv Mei
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Yawei Song
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Huan Yan
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, Guangzhou National Laboratory, Guangzhou Medical University, Guangzhou, China
| | - Jiajie Yang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Shuheng Wu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Jiao Yuan
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, Guangzhou National Laboratory, Guangzhou Medical University, Guangzhou, China
| | - Wei Wu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| |
Collapse
|
11
|
Razzaq A, Bejaoui Y, Alam T, Saad M, El Hajj N. Ribosomal DNA Copy Number Variation is Coupled with DNA Methylation Changes at the 45S rDNA Locus. Epigenetics 2023; 18:2229203. [PMID: 37368968 DOI: 10.1080/15592294.2023.2229203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 06/04/2023] [Accepted: 06/20/2023] [Indexed: 06/29/2023] Open
Abstract
The human ribosomal DNA (rDNA) copy number (CN) has been challenging to analyse, and its sequence has been excluded from reference genomes due to its highly repetitive nature. The 45S rDNA locus encodes essential components of the cell, nevertheless rDNA displays high inter-individual CN variation that could influence human health and disease. CN alterations in rDNA have been hypothesized as a possible factor in autism spectrum disorders (ASD) and were shown to be altered in Schizophrenia patients. We tested whether whole-genome bisulphite sequencing can be used to simultaneously quantify rDNA CN and measure DNA methylation at the 45S rDNA locus. Using this approach, we observed high inter-individual variation in rDNA CN, and limited intra-individual copy differences in several post-mortem tissues. Furthermore, we did not observe any significant alterations in rDNA CN or DNA methylation in Autism Spectrum Disorder (ASD) brains in 16 ASD vs 11 control samples. Similarly, no difference was detected when comparing neurons form 28 Schizophrenia (Scz) patients vs 25 controls or oligodendrocytes from 22 Scz samples vs 20 controls. However, our analysis revealed a strong positive correlation between CN and DNA methylation at the 45S rDNA locus in multiple tissues. This was observed in brain and confirmed in small intestine, adipose tissue, and gastric tissue. This should shed light on a possible dosage compensation mechanism that silences additional rDNA copies to ensure homoeostatic regulation of ribosome biogenesis.
Collapse
Affiliation(s)
- Aleem Razzaq
- College of Health and Life Sciences, Qatar Foundation, Hamad Bin Khalifa University, Doha, Qatar
| | - Yosra Bejaoui
- College of Health and Life Sciences, Qatar Foundation, Hamad Bin Khalifa University, Doha, Qatar
| | - Tanvir Alam
- College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar
| | - Mohamad Saad
- Qatar Computing Research Institute, Hamad Bin Khalifa University, Doha, Qatar
| | - Nady El Hajj
- College of Health and Life Sciences, Qatar Foundation, Hamad Bin Khalifa University, Doha, Qatar
- College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar
| |
Collapse
|
12
|
Smirnov E, Molínová P, Chmúrčiaková N, Vacík T, Cmarko D. Non-canonical DNA structures in the human ribosomal DNA. Histochem Cell Biol 2023; 160:499-515. [PMID: 37750997 DOI: 10.1007/s00418-023-02233-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2023] [Indexed: 09/27/2023]
Abstract
Non-canonical structures (NCS) refer to the various forms of DNA that differ from the B-conformation described by Watson and Crick. It has been found that these structures are usual components of the genome, actively participating in its essential functions. The present review is focused on the nine kinds of NCS appearing or likely to appear in human ribosomal DNA (rDNA): supercoiling structures, R-loops, G-quadruplexes, i-motifs, DNA triplexes, cruciform structures, DNA bubbles, and A and Z DNA conformations. We discuss the conditions of their generation, including their sequence specificity, distribution within the locus, dynamics, and beneficial and detrimental role in the cell.
Collapse
Affiliation(s)
- Evgeny Smirnov
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic.
| | - Pavla Molínová
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Nikola Chmúrčiaková
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Tomáš Vacík
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| | - Dušan Cmarko
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00, Prague, Czech Republic
| |
Collapse
|
13
|
Showman S, Talbert PB, Xu Y, Adeyemi RO, Henikoff S. Expansion of human centromeric arrays in cells undergoing break-induced replication. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.11.566714. [PMID: 38014305 PMCID: PMC10680626 DOI: 10.1101/2023.11.11.566714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Human centromeres are located within α-satellite arrays and evolve rapidly, which can lead to individual variation in array lengths. Proposed mechanisms for such alterations in lengths are unequal cross-over between sister chromatids, gene conversion, and break-induced replication. However, the underlying molecular mechanisms responsible for the massive, complex, and homogeneous organization of centromeric arrays have not been experimentally validated. Here, we use droplet digital PCR assays to demonstrate that centromeric arrays can expand and contract within ~20 somatic cell divisions of a cell line. We find that the frequency of array variation among single-cell-derived subclones ranges from a minimum of ~7% to a maximum of ~100%. Further clonal evolution revealed that centromere expansion is favored over contraction. We find that the homologous recombination protein RAD52 and the helicase PIF1 are required for extensive array change, suggesting that centromere sequence evolution can occur via break-induced replication.
Collapse
Affiliation(s)
- Soyeon Showman
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Paul B. Talbert
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Yiling Xu
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Richard O. Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| |
Collapse
|
14
|
Agabekian IA, Abdulkina LR, Lushnenko AY, Young PG, Valeeva LR, Boskovic O, Lilly EG, Sharipova MR, Shippen DE, Juenger TE, Shakirov EV. Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control. RESEARCH SQUARE 2023:rs.3.rs-3438810. [PMID: 37961382 PMCID: PMC10635316 DOI: 10.21203/rs.3.rs-3438810/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a - deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.
Collapse
Affiliation(s)
- Inna A Agabekian
- Kazan Federal University: Kazanskij Privolzskij federal'nyj universitet
| | | | - Alina Y Lushnenko
- Kazan Federal University: Kazanskij Privolzskij federal'nyj universitet
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Sharp NP, Smith DR, Driscoll G, Sun K, Vickerman CM, Martin SCT. Contribution of Spontaneous Mutations to Quantitative and Molecular Variation at the Highly Repetitive rDNA Locus in Yeast. Genome Biol Evol 2023; 15:evad179. [PMID: 37847861 PMCID: PMC10581546 DOI: 10.1093/gbe/evad179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2023] [Indexed: 10/19/2023] Open
Abstract
The ribosomal DNA array in Saccharomyces cerevisiae consists of many tandem repeats whose copy number is believed to be functionally important but highly labile. Regulatory mechanisms have evolved to maintain copy number by directed mutation, but how spontaneous variation at this locus is generated and selected has not been well characterized. We applied a mutation accumulation approach to quantify the impacts of mutation and selection on this unique genomic feature across hundreds of mutant strains. We find that mutational variance for this trait is relatively high, and that unselected mutations elsewhere in the genome can disrupt copy number maintenance. In consequence, copy number generally declines gradually, consistent with a previously proposed model of rDNA maintenance where a downward mutational bias is normally compensated by mechanisms that increase copy number when it is low. This pattern holds across ploidy levels and strains in the standard lab environment but differs under some stressful conditions. We identify several alleles, gene categories, and genomic features that likely affect copy number, including aneuploidy for chromosome XII. Copy number change is associated with reduced growth in diploids, consistent with stabilizing selection. Levels of standing variation in copy number are well predicted by a balance between mutation and stabilizing selection, suggesting this trait is not subject to strong diversifying selection in the wild. The rate and spectrum of point mutations within the rDNA locus itself are distinct from the rest of the genome and predictive of polymorphism locations. Our findings help differentiate the roles of mutation and selection and indicate that spontaneous mutation patterns shape several aspects of ribosomal DNA evolution.
Collapse
Affiliation(s)
- Nathaniel P Sharp
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Denise R Smith
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gregory Driscoll
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kexin Sun
- Present address: Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina, USA
| | | | - Sterling C T Martin
- Present address: Department of Biology, Washington University, St. Louis, Missouri, USA
| |
Collapse
|
16
|
Bâcle J, Groizard L, Kumanski S, Moriel-Carretero M. Nuclear envelope-remodeling events as models to assess the potential role of membranes on genome stability. FEBS Lett 2023; 597:1946-1956. [PMID: 37339935 DOI: 10.1002/1873-3468.14688] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/31/2023] [Accepted: 05/31/2023] [Indexed: 06/22/2023]
Abstract
The nuclear envelope (NE) encloses the genetic material and functions in chromatin organization and stability. In Saccharomyces cerevisiae, the NE is bound to the ribosomal DNA (rDNA), highly repeated and transcribed, thus prone to genetic instability. While tethering limits instability, it simultaneously triggers notable NE remodeling. We posit here that NE remodeling may contribute to genome integrity maintenance. The NE importance in genome expression, structure, and integrity is well recognized, yet studies mostly focus on peripheral proteins and nuclear pores, not on the membrane itself. We recently characterized a NE invagination drastically obliterating the rDNA, which we propose here as a model to probe if and how membranes play an active role in genome stability preservation.
Collapse
Affiliation(s)
- Janélie Bâcle
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| | - Léa Groizard
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| | - Sylvain Kumanski
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| | - María Moriel-Carretero
- Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Centre National de la Recherche Scientifique, Université de Montpellier, France
| |
Collapse
|
17
|
Santana-Sosa S, Matos-Perdomo E, Ayra-Plasencia J, Machín F. A Yeast Mitotic Tale for the Nucleus and the Vacuoles to Embrace. Int J Mol Sci 2023; 24:9829. [PMID: 37372977 DOI: 10.3390/ijms24129829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/02/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
The morphology of the nucleus is roughly spherical in most eukaryotic cells. However, this organelle shape needs to change as the cell travels through narrow intercellular spaces during cell migration and during cell division in organisms that undergo closed mitosis, i.e., without dismantling the nuclear envelope, such as yeast. In addition, the nuclear morphology is often modified under stress and in pathological conditions, being a hallmark of cancer and senescent cells. Thus, understanding nuclear morphological dynamics is of uttermost importance, as pathways and proteins involved in nuclear shaping can be targeted in anticancer, antiaging, and antifungal therapies. Here, we review how and why the nuclear shape changes during mitotic blocks in yeast, introducing novel data that associate these changes with both the nucleolus and the vacuole. Altogether, these findings suggest a close relationship between the nucleolar domain of the nucleus and the autophagic organelle, which we also discuss here. Encouragingly, recent evidence in tumor cell lines has linked aberrant nuclear morphology to defects in lysosomal function.
Collapse
Affiliation(s)
- Silvia Santana-Sosa
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Emiliano Matos-Perdomo
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Jessel Ayra-Plasencia
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Félix Machín
- Research Unit, University Hospital Ntra Sra de Candelaria, Ctra del Rosario 145, 38010 Santa Cruz de Tenerife, Spain
- Institute of Biomedical Technologies, University of La Laguna, 38200 San Cristóbal de La Laguna, Spain
- Faculty of Health Sciences, Fernando Pessoa Canarias University, 35450 Santa María de Guía, Spain
| |
Collapse
|
18
|
Morton EA, Hall AN, Cuperus JT, Queitsch C. Substantial rDNA copy number reductions alter timing of development and produce variable tissue-specific phenotypes in C. elegans. Genetics 2023; 224:iyad039. [PMID: 36919976 PMCID: PMC10474940 DOI: 10.1093/genetics/iyad039] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 03/16/2023] Open
Abstract
The genes that encode ribosomal RNAs are present in several hundred copies in most eukaryotes. These vast arrays of repetitive ribosomal DNA (rDNA) have been implicated not just in ribosome biogenesis, but also aging, cancer, genome stability, and global gene expression. rDNA copy number is highly variable among and within species; this variability is thought to associate with traits relevant to human health and disease. Here we investigate the phenotypic consequences of multicellular life at the lower bounds of rDNA copy number. We use the model Caenorhabditis elegans, which has previously been found to complete embryogenesis using only maternally provided ribosomes. We find that individuals with rDNA copy number reduced to ∼5% of wild type are capable of further development with variable penetrance. Such individuals are sterile and exhibit severe morphological defects, particularly in post-embryonically dividing tissues such as germline and vulva. Developmental completion and fertility are supported by an rDNA copy number ∼10% of wild type, with substantially delayed development. Worms with rDNA copy number reduced to ∼33% of wild type display a subtle developmental timing defect that was absent in worms with higher copy numbers. Our results support the hypothesis that rDNA requirements vary across tissues and indicate that the minimum rDNA copy number for fertile adulthood is substantially less than the lowest naturally observed total copy number. The phenotype of individuals with severely reduced rDNA copy number is highly variable in penetrance and presentation, highlighting the need for continued investigation into the biological consequences of rDNA copy number variation.
Collapse
Affiliation(s)
| | - Ashley N Hall
- Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI 53726, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| |
Collapse
|
19
|
Ni C, Buszczak M. The homeostatic regulation of ribosome biogenesis. Semin Cell Dev Biol 2023; 136:13-26. [PMID: 35440410 PMCID: PMC9569395 DOI: 10.1016/j.semcdb.2022.03.043] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 12/22/2022]
Abstract
The continued integrity of biological systems depends on a balance between interdependent elements at the molecular, cellular, and organismal levels. This is particularly true for the generation of ribosomes, which influence almost every aspect of cell and organismal biology. Ribosome biogenesis (RiBi) is an energetically demanding process that involves all three RNA polymerases, numerous RNA processing factors, chaperones, and the coordinated expression of 79-80 ribosomal proteins (r-proteins). Work over the last several decades has revealed that the dynamic regulation of ribosome production represents a major mechanism by which cells maintain homeostasis in response to changing environmental conditions and acute stress. More recent studies suggest that cells and tissues within multicellular organisms exhibit dramatically different levels of ribosome production and protein synthesis, marked by the differential expression of RiBi factors. Thus, distinct bottlenecks in the RiBi process, downstream of rRNA transcription, may exist within different cell populations of multicellular organisms during development and in adulthood. This review will focus on our current understanding of the mechanisms that link the complex molecular process of ribosome biogenesis with cellular and organismal physiology. We will discuss diverse topics including how different steps in the RiBi process are coordinated with one another, how MYC and mTOR impact RiBi, and how RiBi levels change between stem cells and their differentiated progeny. In turn, we will also review how regulated changes in ribosome production itself can feedback to influence cell fate and function.
Collapse
Affiliation(s)
- Chunyang Ni
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA
| | - Michael Buszczak
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
| |
Collapse
|
20
|
Comparative Research: Regulatory Mechanisms of Ribosomal Gene Transcription in Saccharomyces cerevisiae and Schizosaccharomyces pombe. Biomolecules 2023; 13:biom13020288. [PMID: 36830657 PMCID: PMC9952952 DOI: 10.3390/biom13020288] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
Restricting ribosome biosynthesis and assembly in response to nutrient starvation is a universal phenomenon that enables cells to survive with limited intracellular resources. When cells experience starvation, nutrient signaling pathways, such as the target of rapamycin (TOR) and protein kinase A (PKA), become quiescent, leading to several transcription factors and histone modification enzymes cooperatively and rapidly repressing ribosomal genes. Fission yeast has factors for heterochromatin formation similar to mammalian cells, such as H3K9 methyltransferase and HP1 protein, which are absent in budding yeast. However, limited studies on heterochromatinization in ribosomal genes have been conducted on fission yeast. Herein, we shed light on and compare the regulatory mechanisms of ribosomal gene transcription in two species with the latest insights.
Collapse
|
21
|
Regulation of ribosomal RNA gene copy number, transcription and nucleolus organization in eukaryotes. Nat Rev Mol Cell Biol 2023; 24:414-429. [PMID: 36732602 DOI: 10.1038/s41580-022-00573-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2022] [Indexed: 02/04/2023]
Abstract
One of the first biological machineries to be created seems to have been the ribosome. Since then, organisms have dedicated great efforts to optimize this apparatus. The ribosomal RNA (rRNA) contained within ribosomes is crucial for protein synthesis and maintenance of cellular function in all known organisms. In eukaryotic cells, rRNA is produced from ribosomal DNA clusters of tandem rRNA genes, whose organization in the nucleolus, maintenance and transcription are strictly regulated to satisfy the substantial demand for rRNA required for ribosome biogenesis. Recent studies have elucidated mechanisms underlying the integrity of ribosomal DNA and regulation of its transcription, including epigenetic mechanisms and a unique recombination and copy-number control system to stably maintain high rRNA gene copy number. In this Review, we disucss how the crucial maintenance of rRNA gene copy number through control of gene amplification and of rRNA production by RNA polymerase I are orchestrated. We also discuss how liquid-liquid phase separation controls the architecture and function of the nucleolus and the relationship between rRNA production, cell senescence and disease.
Collapse
|
22
|
de Moraes RLR, Sassi FDMC, Marinho MMF, Ráb P, Porto JIR, Feldberg E, Cioffi MDB. Small Body, Large Chromosomes: Centric Fusions Shaped the Karyotype of the Amazonian Miniature Fish Nannostomus anduzei (Characiformes, Lebiasinidae). Genes (Basel) 2023; 14:192. [PMID: 36672933 PMCID: PMC9858914 DOI: 10.3390/genes14010192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/04/2023] [Accepted: 01/10/2023] [Indexed: 01/13/2023] Open
Abstract
Miniature refers to species with extraordinarily small adult body size when adult and can be found within all major metazoan groups. It is considered that miniature species have experienced severe alteration of numerous morphological traits during evolution. For a variety of reasons, including severe labor concerns during collecting, chromosomal acquisition, and taxonomic issues, miniature fishes are neglected and understudied. Since some available studies indicate possible relationship between diploid chromosome number (2n) and body size in fishes, we aimed to study one of the smallest Neotropical fish Nannostomus anduzei (Teleostei, Characiformes, Lebiasinidae), using both conventional (Giemsa staining, C-banding) and molecular cytogenetic methods (FISH mapping of rDNAs, microsatellites, and telomeric sequences). Our research revealed that N. anduzei possesses one of the lowest diploid chromosome numbers (2n = 22) among teleost fishes, and its karyotype is entirely composed of large metacentric chromosomes. All chromosomes, except for pair number 11, showed an 18S rDNA signal in the pericentromeric region. 5S rDNA signals were detected in the pericentromeric regions of chromosome pair number 1 and 6, displaying synteny to 18S rDNA signals. Interstitial telomeric sites (ITS) were identified in the centromeric region of pairs 6 and 8, indicating that centric fusions played a significant role in karyotype evolution of studied species. Our study provides further evidence supporting the trend of diploid chromosome number reduction along with miniaturization of adult body size in fishes.
Collapse
Affiliation(s)
- Renata Luiza Rosa de Moraes
- Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luiz Km. 235, C.P. 676, São Carlos 13565-905, SP, Brazil
| | - Francisco de Menezes Cavalcante Sassi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luiz Km. 235, C.P. 676, São Carlos 13565-905, SP, Brazil
| | - Manoela Maria Ferreira Marinho
- Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, Cidade Universitária, Castelo Branco, João Pessoa 58051-900, PB, Brazil
| | - Petr Ráb
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Rumburská 89, 277 21 Liběchov, Czech Republic
| | - Jorge Ivan Rebelo Porto
- Laboratório de Genética Animal, Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo 2936, Petrópolis, Manaus 69067-375, AM, Brazil
| | - Eliana Feldberg
- Laboratório de Genética Animal, Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo 2936, Petrópolis, Manaus 69067-375, AM, Brazil
| | - Marcelo de Bello Cioffi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luiz Km. 235, C.P. 676, São Carlos 13565-905, SP, Brazil
| |
Collapse
|
23
|
Greco M, Morard R, Darling K, Kucera M. Macroevolutionary patterns in intragenomic rDNA variability among planktonic foraminifera. PeerJ 2023; 11:e15255. [PMID: 37123000 PMCID: PMC10143585 DOI: 10.7717/peerj.15255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 03/28/2023] [Indexed: 05/02/2023] Open
Abstract
Ribosomal intragenomic variability in prokaryotes and eukaryotes is a genomic feature commonly studied for its inflationary impact on molecular diversity assessments. However, the evolutionary mechanisms and distribution of this phenomenon within a microbial group are rarely explored. Here, we investigate the intragenomic variability in 33 species of planktonic foraminifera, calcifying marine protists, by inspecting 2,403 partial SSU sequences obtained from single-cell clone libraries. Our analyses show that polymorphisms are common among planktonic foraminifera species, but the number of polymorphic sites significantly differs among clades. With our molecular simulations, we could assess that most of these mutations are located in paired regions that do not affect the secondary structure of the SSU fragment. Finally, by mapping the number of polymorphic sites on the phylogeny of the clades, we were able to discuss the evolution and potential sources of intragenomic variability in planktonic foraminifera, linking this trait to the distinctive nuclear and genomic dynamics of this microbial group.
Collapse
Affiliation(s)
- Mattia Greco
- Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Institut de Ciències del Mar (ICM), Consejo Superior de Investigaciones Científicas, Barcelona, Spain
| | - Raphaël Morard
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Kate Darling
- School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom
- Biological and Environmental Sciences, University of Stirling, Stirling, United Kingdom
| | - Michal Kucera
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| |
Collapse
|
24
|
Research on Werner Syndrome: Trends from Past to Present and Future Prospects. Genes (Basel) 2022; 13:genes13101802. [PMID: 36292687 PMCID: PMC9601476 DOI: 10.3390/genes13101802] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/02/2022] [Accepted: 10/04/2022] [Indexed: 11/17/2022] Open
Abstract
A rare and autosomal recessive premature aging disorder, Werner syndrome (WS) is characterized by the early onset of aging-associated diseases, including shortening stature, alopecia, bilateral cataracts, skin ulcers, diabetes, osteoporosis, arteriosclerosis, and chromosomal instability, as well as cancer predisposition. WRN, the gene responsible for WS, encodes DNA helicase with a 3′ to 5′ exonuclease activity, and numerous studies have revealed that WRN helicase is involved in the maintenance of chromosome stability through actions in DNA, e.g., DNA replication, repair, recombination, and epigenetic regulation via interaction with DNA repair factors, telomere-binding proteins, histone modification enzymes, and other DNA metabolic factors. However, although these efforts have elucidated the cellular functions of the helicase in cell lines, they have not been linked to the treatment of the disease. Life expectancy has improved for WS patients over the past three decades, and it is hoped that a fundamental treatment for the disease will be developed. Disease-specific induced pluripotent stem (iPS) cells have been established, and these are expected to be used in drug discovery and regenerative medicine for WS patients. In this article, we review trends in research to date and present some perspectives on WS research with regard to the application of pluripotent stem cells. Furthermore, the elucidation of disease mechanisms and drug discovery utilizing the vast amount of scientific data accumulated to date will be discussed.
Collapse
|
25
|
Therapeutic Effect of Melatonin in Premature Ovarian Insufficiency: Hippo Pathway Is Involved. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:3425877. [PMID: 36017238 PMCID: PMC9398856 DOI: 10.1155/2022/3425877] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/20/2022] [Accepted: 08/01/2022] [Indexed: 11/23/2022]
Abstract
Objective Premature ovarian insufficiency (POI) is a female reproductive disorder of unknown etiology with no definite pathogenesis. Melatonin (MT) is an endogenous hormone synthesized mainly by pineal cells and has strong endogenous effects in regulating ovarian function. To systematically explore the pharmacological mechanism of MT on POI therapy, a literature review approach was conducted at the signaling pathways level. Methods Relevant literatures were searched and downloaded from databases, including PubMed and China National Knowledge Infrastructure, using the keywords “premature ovarian insufficiency,” “Hippo signaling pathways,” and “melatonin.” The search criteria were from 2010 to 2022. Text mining was also performed. Results MT is involved in the regulation of Hippo signaling pathway in a variety of modes and has been correlated with ovarian function. Conclusions The purpose of this review is to summarize the research progress of Hippo signaling pathways and significance of MT in POI, the potential crosstalk between MT and Hippo signaling pathways, and the prospective therapy.
Collapse
|
26
|
Watase GJ, Nelson JO, Yamashita YM. Nonrandom sister chromatid segregation mediates rDNA copy number maintenance in Drosophila. SCIENCE ADVANCES 2022; 8:eabo4443. [PMID: 35895823 PMCID: PMC9328678 DOI: 10.1126/sciadv.abo4443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/10/2022] [Indexed: 06/15/2023]
Abstract
Although considered to be exact copies of each other, sister chromatids can segregate nonrandomly in some cases. For example, sister chromatids of the X and Y chromosomes segregate nonrandomly during asymmetric division of male germline stem cells (GSCs) in Drosophila melanogaster. Here, we demonstrate that the ribosomal DNA (rDNA) loci, which are located on the X and Y chromosomes, and an rDNA binding protein Indra are required for nonrandom sister chromatid segregation (NRSS). We provide the evidence that NRSS, following unequal sister chromatid exchange, is a mechanism by which GSCs recover rDNA copy number, counteracting the spontaneous copy number loss that occurs during aging. Our study reveals an unexpected role for NRSS in maintaining germline immortality through maintenance of a vulnerable genomic element, rDNA.
Collapse
Affiliation(s)
- George J. Watase
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, 455 Main Street, Cambridge, MA 02142, USA
| | - Jonathan O. Nelson
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, 455 Main Street, Cambridge, MA 02142, USA
| | - Yukiko M. Yamashita
- Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, 455 Main Street, Cambridge, MA 02142, USA
| |
Collapse
|
27
|
Jagadeesan SK, Potter T, Al-Gafari M, Hooshyar M, Hewapathirana CM, Takallou S, Hajikarimlou M, Burnside D, Samanfar B, Moteshareie H, Smith M, Golshani A. Discovery and identification of genes involved in DNA damage repair in yeast. Gene 2022; 831:146549. [PMID: 35569766 DOI: 10.1016/j.gene.2022.146549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 02/16/2022] [Accepted: 05/06/2022] [Indexed: 11/04/2022]
Abstract
DNA repair defects are common in tumour cells and can lead to misrepair of double-strand breaks (DSBs), posing a significant challenge to cellular integrity. The overall mechanisms of DSB have been known for decades. However, the list of the genes that affect the efficiency of DSB repair continues to grow. Additional factors that play a role in DSB repair pathways have yet to be identified. In this study, we present a computational approach to identify novel gene functions that are involved in DNA damage repair in Saccharomyces cerevisiae. Among the primary candidates, GAL7, YMR130W, and YHI9 were selected for further analysis since they had not previously been identified as being active in DNA repair pathways. Originally, GAL7 was linked to galactose metabolism. YHI9 and YMR130W encode proteins of unknown functions. Laboratory testing of deletion strains gal7Δ, ymr130wΔ, and yhi9Δ implicated all 3 genes in Homologous Recombination (HR) and/or Non-Homologous End Joining (NHEJ) repair pathways, and enhanced sensitivity to DNA damage-inducing drugs suggested involvement in the broader DNA damage repair machinery. A subsequent genetic interaction analysis revealed interconnections of these three genes, most strikingly through SIR2, SIR3 and SIR4 that are involved in chromatin regulation and DNA damage repair network.
Collapse
Affiliation(s)
- Sasi Kumar Jagadeesan
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Taylor Potter
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Mustafa Al-Gafari
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Mohsen Hooshyar
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | | | - Sarah Takallou
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Maryam Hajikarimlou
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Daniel Burnside
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Bahram Samanfar
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre (ORDC), Ottawa, Ontario, Canada.
| | - Houman Moteshareie
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Myron Smith
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada.
| | - Ashkan Golshani
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada; Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| |
Collapse
|
28
|
Abstract
Genome instability causes cellular senescence in many organisms. The rRNA gene cluster (rDNA) is one of the most unstable regions in the genome and this instability might convey a signal that induces senescence in the budding yeast. The instability of rDNA mostly depends on replication fork blocking (RFB) activity which induces recombination and gene amplification. By overexpression of Fob1, responsible for the RFB activity, we found that unstable rDNA induces cell cycle arrest and restricts replicative life span. We isolated yeast mutants that grew normally while Fob1 was overexpressed, expecting that some of the mutated genes would be related to the production of a “senescence signal” that elongates cell cycle, stops cell division and finally restricts replicative life span. Our screen identified three suppressor genes, RPS12, UBC4, and CCR4. Replicative life spans of the rps12 and ubc4 mutants were longer than that of wild-type cells. An increase in the levels of extrachromosomal rDNA circles and noncoding transcripts, known to shorten replicative life span, was observed in ubc4 and rps12 respectively, while DNA double strand-breaks at the RFB that are triggers of rDNA instability were reduced in the rps12 mutant. Overall, our observations indicate that Rps12 and Ubc4 contribute to the connection between rDNA instability and replicative life span.
Collapse
|
29
|
Abstract
Centromeres, the chromosomal loci where spindle fibers attach during cell division to segregate chromosomes, are typically found within satellite arrays in plants and animals. Satellite arrays have been difficult to analyze because they comprise megabases of tandem head-to-tail highly repeated DNA sequences. Much evidence suggests that centromeres are epigenetically defined by the location of nucleosomes containing the centromere-specific histone H3 variant cenH3, independently of the DNA sequences where they are located; however, the reason that cenH3 nucleosomes are generally found on rapidly evolving satellite arrays has remained unclear. Recently, long-read sequencing technology has clarified the structures of satellite arrays and sparked rethinking of how they evolve, and new experiments and analyses have helped bring both understanding and further speculation about the role these highly repeated sequences play in centromere identification.
Collapse
Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| |
Collapse
|
30
|
Ding Q, Li R, Ren X, Chan LY, Ho VWS, Xie D, Ye P, Zhao Z. Genomic architecture of 5S rDNA cluster and its variations within and between species. BMC Genomics 2022; 23:238. [PMID: 35346033 PMCID: PMC8961926 DOI: 10.1186/s12864-022-08476-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/16/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ribosomal DNAs (rDNAs) are arranged in purely tandem repeats, preventing them from being reliably assembled onto chromosomes during generation of genome assembly. The uncertainty of rDNA genomic structure presents a significant barrier for studying their function and evolution. RESULTS Here we generate ultra-long Oxford Nanopore Technologies (ONT) and short NGS reads to delineate the architecture and variation of the 5S rDNA cluster in the different strains of C. elegans and C. briggsae. We classify the individual rDNA's repeating units into 25 types based on the unique sequence variations in each unit of C. elegans (N2). We next perform assembly of the cluster by taking advantage of the long reads that carry these units, which led to an assembly of 5S rDNA cluster consisting of up to 167 consecutive 5S rDNA units in the N2 strain. The ordering and copy number of various rDNA units are consistent with the separation time between strains. Surprisingly, we observed a drastically reduced level of variation in the unit composition in the 5S rDNA cluster in the C. elegans CB4856 and C. briggsae AF16 strains than in the C. elegans N2 strain, suggesting that N2, a widely used reference strain, is likely to be defective in maintaining the 5S rDNA cluster stability compared with other wild isolates of C. elegans or C. briggsae. CONCLUSIONS The results demonstrate that Nanopore DNA sequencing reads are capable of generating assembly of highly repetitive sequences, and rDNA units are highly dynamic both within and between population(s) of the same species in terms of sequence and copy number. The detailed structure and variation of the 5S rDNA units within the rDNA cluster pave the way for functional and evolutionary studies.
Collapse
Affiliation(s)
- Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
- Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong SAR, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Lu-Yan Chan
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Vincy W S Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Dongying Xie
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Pohao Ye
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China.
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong SAR, China.
| |
Collapse
|
31
|
Fefelova EA, Pleshakova IM, Mikhaleva EA, Pirogov SA, Poltorachenko V, Abramov Y, Romashin D, Shatskikh A, Blokh R, Gvozdev V, Klenov M. Impaired function of rDNA transcription initiation machinery leads to derepression of ribosomal genes with insertions of R2 retrotransposon. Nucleic Acids Res 2022; 50:867-884. [PMID: 35037046 PMCID: PMC8789037 DOI: 10.1093/nar/gkab1276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 11/21/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic genomes harbor hundreds of rRNA genes, many of which are transcriptionally silent. However, little is known about selective regulation of individual rDNA units. In Drosophila melanogaster, some rDNA repeats contain insertions of the R2 retrotransposon, which is capable to be transcribed only as part of pre-rRNA molecules. rDNA units with R2 insertions are usually inactivated, although R2 expression may be beneficial in cells with decreased rDNA copy number. Here we found that R2-inserted rDNA units are enriched with HP1a and H3K9me3 repressive mark, whereas disruption of the heterochromatin components slightly affects their silencing in ovarian germ cells. Surprisingly, we observed a dramatic upregulation of R2-inserted rRNA genes in ovaries lacking Udd (Under-developed) or other subunits (TAF1b and TAF1c-like) of the SL1-like complex, which is homologues to mammalian Selective factor 1 (SL1) involved in rDNA transcription initiation. Derepression of rRNA genes with R2 insertions was accompanied by a reduction of H3K9me3 and HP1a enrichment. We suggest that the impairment of the SL1-like complex affects a mechanism of selective activation of intact rDNA units which competes with heterochromatin formation. We also propose that R2 derepression may serve as an adaptive response to compromised rRNA synthesis.
Collapse
Affiliation(s)
- Elena A Fefelova
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena 91125, USA
| | - Irina M Pleshakova
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
- Laboratory for Neurobiology of Memory, P.K. Anokhin Institute of Normal Physiology, Moscow 125315, Russia
| | - Elena A Mikhaleva
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Sergei A Pirogov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Valentin A Poltorachenko
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Yuri A Abramov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Daniil D Romashin
- Laboratory of Precision Biosystems, V. N. Orekhovich Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow 119121, Russia
| | - Aleksei S Shatskikh
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Roman S Blokh
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
- Department of Functional Genomics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilova Street, Moscow 119334, Russia
| | - Vladimir A Gvozdev
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| | - Mikhail S Klenov
- Department of Molecular Genetics of the Cell, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute», Moscow 123182, Russia
| |
Collapse
|
32
|
Denisenko O. Epigenetics of Ribosomal RNA Genes. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:S103-S131. [PMID: 35501990 DOI: 10.1134/s0006297922140097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 06/14/2023]
Abstract
This review is focused on biology of genes encoding ribosomal RNA (rRNA) in mammals. rRNA is a structural component of the most abundant cellular molecule, the ribosome. There are many copies of rRNA genes per genome that are under tight transcriptional control by epigenetic mechanisms serving to meet cellular needs in protein synthesis. Curiously, only a fraction of rRNA genes is used even in the fast-growing cells, raising a question why unused copies of these genes have not been lost during evolution. Two plausible explanations are discussed. First, there is evidence that besides their direct function in production of rRNA, ribosomal RNA genes are involved in regulation of many other genes in the nucleus by forming either temporary or persistent complexes with these genes. Second, it seems that rRNA genes also play a role in the maintenance of genome stability, where lower copy number of rRNA genes destabilizes the genome. These "additional" functions of rRNA genes make them recurrent candidate drivers of chronic human diseases and aging. Experimental support for the involvement of these genes in human diseases and potential mechanisms are also discussed.
Collapse
Affiliation(s)
- Oleg Denisenko
- Department of Medicine, University of Washington, Seattle, WA, USA.
| |
Collapse
|
33
|
Jespersen N, Monrroy L, Barandun J. Impact of Genome Reduction in Microsporidia. EXPERIENTIA SUPPLEMENTUM (2012) 2022; 114:1-42. [PMID: 35543997 DOI: 10.1007/978-3-030-93306-7_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Microsporidia represent an evolutionary outlier in the tree of life and occupy the extreme edge of the eukaryotic domain with some of their biological features. Many of these unicellular fungi-like organisms have reduced their genomic content to potentially the lowest limit. With some of the most compacted eukaryotic genomes, microsporidia are excellent model organisms to study reductive evolution and its functional consequences. While the growing number of sequenced microsporidian genomes have elucidated genome composition and organization, a recent increase in complementary post-genomic studies has started to shed light on the impacts of genome reduction in these unique pathogens. This chapter will discuss the biological framework enabling genome minimization and will use one of the most ancient and essential macromolecular complexes, the ribosome, to illustrate the effects of extreme genome reduction on a structural, molecular, and cellular level. We outline how reductive evolution in microsporidia has shaped DNA organization, the composition and function of the ribosome, and the complexity of the ribosome biogenesis process. Studying compacted mechanisms, processes, or macromolecular machines in microsporidia illuminates their unique lifestyle and provides valuable insights for comparative eukaryotic structural biology.
Collapse
Affiliation(s)
- Nathan Jespersen
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
| | - Leonardo Monrroy
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden
| | - Jonas Barandun
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
| |
Collapse
|
34
|
Kasselimi E, Pefani DE, Taraviras S, Lygerou Z. Ribosomal DNA and the nucleolus at the heart of aging. Trends Biochem Sci 2022; 47:328-341. [DOI: 10.1016/j.tibs.2021.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/15/2022]
|
35
|
Wu W, He JN, Lan M, Zhang P, Chu WK. Transcription-Replication Collisions and Chromosome Fragility. Front Genet 2021; 12:804547. [PMID: 34956339 PMCID: PMC8703014 DOI: 10.3389/fgene.2021.804547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
Accurate replication of the entire genome is critical for cell division and propagation. Certain regions in the genome, such as fragile sites (common fragile sites, rare fragile sites, early replicating fragile sites), rDNA and telomeres, are intrinsically difficult to replicate, especially in the presence of replication stress caused by, for example, oncogene activation during tumor development. Therefore, these regions are particularly prone to deletions and chromosome rearrangements during tumorigenesis, rendering chromosome fragility. Although, the mechanism underlying their “difficult-to-replicate” nature and genomic instability is still not fully understood, accumulating evidence suggests transcription might be a major source of endogenous replication stress (RS) leading to chromosome fragility. Here, we provide an updated overview of how transcription affects chromosome fragility. Furthermore, we will use the well characterized common fragile sites (CFSs) as a model to discuss pathways involved in offsetting transcription-induced RS at these loci with a focus on the recently discovered atypical DNA synthesis repair pathway Mitotic DNA Synthesis (MiDAS).
Collapse
Affiliation(s)
- Wei Wu
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Jing Na He
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong, China
| | - Mengjiao Lan
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Pumin Zhang
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Wai Kit Chu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong, China
| |
Collapse
|
36
|
Georgeson J, Schwartz S. The ribosome epitranscriptome: inert-or a platform for functional plasticity? RNA (NEW YORK, N.Y.) 2021; 27:1293-1301. [PMID: 34312287 PMCID: PMC8522695 DOI: 10.1261/rna.078859.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A universal property of all rRNAs explored to date is the prevalence of post-transcriptional ("epitranscriptional") modifications, which expand the chemical and topological properties of the four standard nucleosides. Are these modifications an inert, constitutive part of the ribosome? Or could they, in part, also regulate the structure or function of the ribosome? In this review, we summarize emerging evidence that rRNA modifications are more heterogeneous than previously thought, and that they can also vary from one condition to another, such as in the context of a cellular response or a developmental trajectory. We discuss the implications of these results and key open questions on the path toward connecting such heterogeneity with function.
Collapse
Affiliation(s)
- Joseph Georgeson
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| |
Collapse
|
37
|
Haig D. Concerted evolution of ribosomal DNA: Somatic peace amid germinal strife: Intranuclear and cellular selection maintain the quality of rRNA. Bioessays 2021; 43:e2100179. [PMID: 34704616 DOI: 10.1002/bies.202100179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/12/2021] [Indexed: 11/10/2022]
Abstract
Most eukaryotes possess many copies of rDNA. Organismal selection alone cannot maintain rRNA function because the effects of mutations in one rDNA are diluted by the presence of many other rDNAs. rRNA quality is maintained by processes that increase homogeneity of rRNA within, and heterogeneity among, germ cells thereby increasing the effectiveness of cellular selection on ribosomal function. A successful rDNA repeat will possess adaptations for spreading within tandem arrays by intranuclear selection. These adaptations reside in the non-coding regions of rDNA. Single-copy genes are predicted to manage processes of intranuclear and cellular selection in the germline to maintain the quality of rRNA expressed in somatic cells of future generations.
Collapse
Affiliation(s)
- David Haig
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| |
Collapse
|
38
|
Iida T, Kobayashi T. Establishment of an "in saccharo" experimental system. Genes Genet Syst 2021; 96:107-118. [PMID: 34108346 DOI: 10.1266/ggs.21-00004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Many proteins form complexes that function in reaction pathways. Therefore, to understand protein function, it is necessary to reconstitute complexes and pathways in vitro. However, it is not straightforward to achieve full activity in reconstituted systems. To address this problem, we present a yeast system named "in saccharo" analysis, which uses budding yeast for simultaneous expression and analysis of many kinds of non-host proteins, such as human proteins. For this purpose, vectors that can accommodate many genes are required. Here, we describe the construction of a chromosome vector by insertion of unique barcode sequences (BCs) into the ribosomal RNA gene repeat (rDNA). Each unit of the rDNA has a BC that is used as the target for integration of an external gene. Because rDNA is naturally capable of maintaining many repetitive copies, the vector is expected to retain the numerous external genes that may be required for reconstitution of functional protein complexes and reaction pathways. Consistent with this prediction, we were able to clone three human genes that form the RNA silencing pathway, which has no functional equivalent in budding yeast, and to demonstrate functionality in this in saccharo analysis system.
Collapse
Affiliation(s)
- Tetsushi Iida
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo
| | - Takehiko Kobayashi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| |
Collapse
|
39
|
Tchurikov NA, Kravatsky YV. The Role of rDNA Clusters in Global Epigenetic Gene Regulation. Front Genet 2021; 12:730633. [PMID: 34531902 PMCID: PMC8438155 DOI: 10.3389/fgene.2021.730633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/02/2021] [Indexed: 12/26/2022] Open
Abstract
The regulation of gene expression has been studied for decades, but the underlying mechanisms are still not fully understood. As well as local and distant regulation, there are specific mechanisms of regulation during development and physiological modulation of gene activity in differentiated cells. Current research strongly supports a role for the 3D chromosomal structure in the regulation of gene expression. However, it is not known whether the genome structure reflects the formation of active or repressed chromosomal domains or if these structures play a primary role in the regulation of gene expression. During early development, heterochromatinization of ribosomal DNA (rDNA) is coupled with silencing or activation of the expression of different sets of genes. Although the mechanisms behind this type of regulation are not known, rDNA clusters shape frequent inter-chromosomal contacts with a large group of genes controlling development. This review aims to shed light on the involvement of clusters of ribosomal genes in the global regulation of gene expression. We also discuss the possible role of RNA-mediated and phase-separation mechanisms in the global regulation of gene expression by nucleoli.
Collapse
Affiliation(s)
- Nickolai A Tchurikov
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
| | - Yuri V Kravatsky
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
40
|
Lambert M, Benmoussa A, Diallo I, Ouellet-Boutin K, Dorval V, Majeau N, Joly-Beauparlant C, Droit A, Bergeron A, Têtu B, Fradet Y, Pouliot F, Provost P. Identification of Abundant and Functional dodecaRNAs (doRNAs) Derived from Ribosomal RNA. Int J Mol Sci 2021; 22:9757. [PMID: 34575920 PMCID: PMC8467515 DOI: 10.3390/ijms22189757] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/02/2021] [Accepted: 09/05/2021] [Indexed: 12/17/2022] Open
Abstract
Using a modified RNA-sequencing (RNA-seq) approach, we discovered a new family of unusually short RNAs mapping to ribosomal RNA 5.8S, which we named dodecaRNAs (doRNAs), according to the number of core nucleotides (12 nt) their members contain. Using a new quantitative detection method that we developed, we confirmed our RNA-seq data and determined that the minimal core doRNA sequence and its 13-nt variant C-doRNA (doRNA with a 5' Cytosine) are the two most abundant doRNAs, which, together, may outnumber microRNAs. The C-doRNA/doRNA ratio is stable within species but differed between species. doRNA and C-doRNA are mainly cytoplasmic and interact with heterogeneous nuclear ribonucleoproteins (hnRNP) A0, A1 and A2B1, but not Argonaute 2. Reporter gene activity assays suggest that C-doRNA may function as a regulator of Annexin II receptor (AXIIR) expression. doRNAs are differentially expressed in prostate cancer cells/tissues and may control cell migration. These findings suggest that unusually short RNAs may be more abundant and important than previously thought.
Collapse
Affiliation(s)
- Marine Lambert
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Department of Microbiology, Infectious Diseases and Immunology, Université Laval, Quebec City, QC G1V 4G2, Canada
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Abderrahim Benmoussa
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Department of Microbiology, Infectious Diseases and Immunology, Université Laval, Quebec City, QC G1V 4G2, Canada
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Idrissa Diallo
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Department of Microbiology, Infectious Diseases and Immunology, Université Laval, Quebec City, QC G1V 4G2, Canada
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Katheryn Ouellet-Boutin
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Department of Microbiology, Infectious Diseases and Immunology, Université Laval, Quebec City, QC G1V 4G2, Canada
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Véronique Dorval
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
| | - Nathalie Majeau
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
| | - Charles Joly-Beauparlant
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
- Department of Molecular Medicine, Université Laval, Quebec City, QC G1V 4G2, Canada
| | - Arnaud Droit
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
- Department of Molecular Medicine, Université Laval, Quebec City, QC G1V 4G2, Canada
| | - Alain Bergeron
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
- Department of Surgery, Université Laval, Quebec City, QC G1R 2J6, Canada
| | - Bernard Têtu
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Yves Fradet
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
- Department of Surgery, Université Laval, Quebec City, QC G1R 2J6, Canada
| | - Frédéric Pouliot
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
- Department of Surgery, Université Laval, Quebec City, QC G1R 2J6, Canada
| | - Patrick Provost
- CHU de Québec Research Center/CHUL Pavilion—Université Laval, 2705 boulevard Laurier, Quebec City, QC G1V 4G2, Canada; (M.L.); (A.B.); (I.D.); (K.O.-B.); (N.M.); (C.J.-B.); (A.D.); (A.B.); (B.T.); (Y.F.); (F.P.)
- Department of Microbiology, Infectious Diseases and Immunology, Université Laval, Quebec City, QC G1V 4G2, Canada
- Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
| |
Collapse
|
41
|
Ortega P, Gómez-González B, Aguilera A. Heterogeneity of DNA damage incidence and repair in different chromatin contexts. DNA Repair (Amst) 2021; 107:103210. [PMID: 34416542 DOI: 10.1016/j.dnarep.2021.103210] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/02/2021] [Accepted: 08/11/2021] [Indexed: 11/18/2022]
Abstract
It has been long known that some regions of the genome are more susceptible to damage and mutagenicity than others. Recent advances have determined a critical role of chromatin both in the incidence of damage and in its repair. Thus, chromatin arises as a guardian of the stability of the genome, which is altered in cancer cells. In this review, we focus into the mechanisms by which chromatin influences the occurrence and repair of the most cytotoxic DNA lesions, double-strand breaks, in particular at actively transcribed chromatin or related to DNA replication.
Collapse
Affiliation(s)
- Pedro Ortega
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain.
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| |
Collapse
|
42
|
Ellis DA, Reyes-Martín F, Rodríguez-López M, Cotobal C, Sun XM, Saintain Q, Jeffares DC, Marguerat S, Tallada VA, Bähler J. R-loops and regulatory changes in chronologically ageing fission yeast cells drive non-random patterns of genome rearrangements. PLoS Genet 2021; 17:e1009784. [PMID: 34464389 PMCID: PMC8437301 DOI: 10.1371/journal.pgen.1009784] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 09/13/2021] [Accepted: 08/18/2021] [Indexed: 12/03/2022] Open
Abstract
Aberrant repair of DNA double-strand breaks can recombine distant chromosomal breakpoints. Chromosomal rearrangements compromise genome function and are a hallmark of ageing. Rearrangements are challenging to detect in non-dividing cell populations, because they reflect individually rare, heterogeneous events. The genomic distribution of de novo rearrangements in non-dividing cells, and their dynamics during ageing, remain therefore poorly characterized. Studies of genomic instability during ageing have focussed on mitochondrial DNA, small genetic variants, or proliferating cells. To characterize genome rearrangements during cellular ageing in non-dividing cells, we interrogated a single diagnostic measure, DNA breakpoint junctions, using Schizosaccharomyces pombe as a model system. Aberrant DNA junctions that accumulated with age were associated with microhomology sequences and R-loops. Global hotspots for age-associated breakpoint formation were evident near telomeric genes and linked to remote breakpoints elsewhere in the genome, including the mitochondrial chromosome. Formation of breakpoint junctions at global hotspots was inhibited by the Sir2 histone deacetylase and might be triggered by an age-dependent de-repression of chromatin silencing. An unexpected mechanism of genomic instability may cause more local hotspots: age-associated reduction in an RNA-binding protein triggering R-loops at target loci. This result suggests that biological processes other than transcription or replication can drive genome rearrangements. Notably, we detected similar signatures of genome rearrangements that accumulated in old brain cells of humans. These findings provide insights into the unique patterns and possible mechanisms of genome rearrangements in non-dividing cells, which can be promoted by ageing-related changes in gene-regulatory proteins.
Collapse
Affiliation(s)
- David A. Ellis
- Institute of Healthy Ageing, Department of Genetics, Evolution & Environment, University College London, London, United Kingdom
| | - Félix Reyes-Martín
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - María Rodríguez-López
- Institute of Healthy Ageing, Department of Genetics, Evolution & Environment, University College London, London, United Kingdom
| | - Cristina Cotobal
- Institute of Healthy Ageing, Department of Genetics, Evolution & Environment, University College London, London, United Kingdom
| | - Xi-Ming Sun
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Quentin Saintain
- Institute of Healthy Ageing, Department of Genetics, Evolution & Environment, University College London, London, United Kingdom
| | - Daniel C. Jeffares
- Institute of Healthy Ageing, Department of Genetics, Evolution & Environment, University College London, London, United Kingdom
| | - Samuel Marguerat
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Víctor A. Tallada
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - Jürg Bähler
- Institute of Healthy Ageing, Department of Genetics, Evolution & Environment, University College London, London, United Kingdom
| |
Collapse
|
43
|
Guo YM, Sun TC, Wang HP, Chen X. Research progress of melatonin (MT) in improving ovarian function: a review of the current status. Aging (Albany NY) 2021; 13:17930-17947. [PMID: 34228638 PMCID: PMC8312436 DOI: 10.18632/aging.203231] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 06/14/2021] [Indexed: 12/17/2022]
Abstract
Melatonin (MT) is an endogenous hormone mainly synthesized by pineal cells, which has strong endogenous effects of eliminating free radicals and resisting oxidative damages. Melatonin (MT) can not only regulate the body’s seasonal and circadian rhythms; but also delay ovarian senescence, regulate ovarian biological rhythm, promote follicles formation, and improve oocyte quality and fertilization rate. This review aimd to provide evidence concerning the synthesis and distribution, ovarian function, and role of MT in development of follicles and oocytes. Moreover, the role of MT as antioxidative, participating in biological rhythm regulation, was also reviewed. Furthermore, the effects of MT on various ovarian related diseases were analyzed, particularly for the ovarian aging and polycystic ovary syndrome (PCOS).
Collapse
Affiliation(s)
- Yi Ming Guo
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.,National Engineering Research Center of Reproductive Health, National Research Institute for Family Planning, Beijing 100081, China
| | - Tie Cheng Sun
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University International Hospital, Beijing 102206, China
| | - Hui Ping Wang
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.,National Engineering Research Center of Reproductive Health, National Research Institute for Family Planning, Beijing 100081, China
| | - Xi Chen
- Reproductive Medical Center, Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China
| |
Collapse
|
44
|
Jernfors T, Danforth J, Kesäniemi J, Lavrinienko A, Tukalenko E, Fajkus J, Dvořáčková M, Mappes T, Watts PC. Expansion of rDNA and pericentromere satellite repeats in the genomes of bank voles Myodes glareolus exposed to environmental radionuclides. Ecol Evol 2021; 11:8754-8767. [PMID: 34257925 PMCID: PMC8258220 DOI: 10.1002/ece3.7684] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/27/2021] [Accepted: 05/05/2021] [Indexed: 12/21/2022] Open
Abstract
Altered copy number of certain highly repetitive regions of the genome, such as satellite DNA within heterochromatin and ribosomal RNA loci (rDNA), is hypothesized to help safeguard the genome against damage derived from external stressors. We quantified copy number of the 18S rDNA and a pericentromeric satellite DNA (Msat-160) in bank voles (Myodes glareolus) inhabiting the Chernobyl Exclusion Zone (CEZ), an area that is contaminated by radionuclides and where organisms are exposed to elevated levels of ionizing radiation. We found a significant increase in 18S rDNA and Msat-160 content in the genomes of bank voles from contaminated locations within the CEZ compared with animals from uncontaminated locations. Moreover, 18S rDNA and Msat-160 copy number were positively correlated in the genomes of bank voles from uncontaminated, but not in the genomes of animals inhabiting contaminated, areas. These results show the capacity for local-scale geographic variation in genome architecture and are consistent with the genomic safeguard hypothesis. Disruption of cellular processes related to genomic stability appears to be a hallmark effect in bank voles inhabiting areas contaminated by radionuclides.
Collapse
Affiliation(s)
- Toni Jernfors
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - John Danforth
- Department of Biochemistry & Molecular BiologyRobson DNA Science CentreArnie Charbonneau Cancer InstituteCumming School of MedicineUniversity of CalgaryCalgaryCanada
| | - Jenni Kesäniemi
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Anton Lavrinienko
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Eugene Tukalenko
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
- National Research Center for Radiation Medicine of the National Academy of Medical ScienceKyivUkraine
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and ProteomicsCentral European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
- Laboratory of Functional Genomics and ProteomicsNCBRFaculty of ScienceMasaryk UniversityBrnoCzech Republic
- Department of Cell Biology and RadiobiologyInstitute of Biophysics of the Czech Academy of SciencesBrnoCzech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and ProteomicsCentral European Institute of Technology (CEITEC)Masaryk UniversityBrnoCzech Republic
| | - Tapio Mappes
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Phillip C. Watts
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| |
Collapse
|
45
|
Lopez FB, Fort A, Tadini L, Probst AV, McHale M, Friel J, Ryder P, Pontvianne F, Pesaresi P, Sulpice R, McKeown P, Brychkova G, Spillane C. Gene dosage compensation of rRNA transcript levels in Arabidopsis thaliana lines with reduced ribosomal gene copy number. THE PLANT CELL 2021; 33:1135-1150. [PMID: 33793816 PMCID: PMC8225240 DOI: 10.1093/plcell/koab020] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 12/24/2020] [Indexed: 05/08/2023]
Abstract
The 45S rRNA genes (rDNA) are among the largest repetitive elements in eukaryotic genomes. rDNA consists of tandem arrays of rRNA genes, many of which are transcriptionally silenced. Silent rDNA repeats may act as 'back-up' copies for ribosome biogenesis and have nuclear organization roles. Through Cas9-mediated genome editing in the Arabidopsis thaliana female gametophyte, we reduced 45S rDNA copy number (CN) to a plateau of ∼10%. Two independent lines had rDNA CNs reduced by up to 90% at the T7 generation, named low copy number (LCN) lines. Despite drastic reduction of rDNA copies, rRNA transcriptional rates, and steady-state levels remained the same as wild-type plants. Gene dosage compensation of rRNA transcript levels was associated with reduction of silencing histone marks at rDNA loci and altered Nucleolar Organiser Region 2 organization. Although overall genome integrity of LCN lines appears unaffected, a chromosome segmental duplication occurred in one of the lines. Transcriptome analysis of LCN seedlings identified several shared dysregulated genes and pathways in both independent lines. Cas9 genome editing of rRNA repeats to generate LCN lines provides a powerful technique to elucidate rDNA dosage compensation mechanisms and impacts of low rDNA CN on genome stability, development, and cellular processes.
Collapse
Affiliation(s)
- Francesca B Lopez
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Antoine Fort
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
- Systems Biology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Luca Tadini
- Dipartimento di Bioscienze, Universit� degli Studi di Milano, 20133 Milano, Italy
| | - Aline V Probst
- CNRS, GReD, Universit� Clermont Auvergne, INSERM, 63001 Clermont–Ferrand, France
| | - Marcus McHale
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
- Systems Biology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - James Friel
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Peter Ryder
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Fr�d�ric Pontvianne
- CNRS, Laboratoire G�nome et D�veloppement des Plantes (LGDP), Universit� de Perpignan Via Domitia, Perpignan, France
| | - Paolo Pesaresi
- Dipartimento di Bioscienze, Universit� degli Studi di Milano, 20133 Milano, Italy
| | - Ronan Sulpice
- Systems Biology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Peter McKeown
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Galina Brychkova
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Charles Spillane
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
- Author for correspondence:
| |
Collapse
|
46
|
Shyian M, Shore D. Approaching Protein Barriers: Emerging Mechanisms of Replication Pausing in Eukaryotes. Front Cell Dev Biol 2021; 9:672510. [PMID: 34124054 PMCID: PMC8194067 DOI: 10.3389/fcell.2021.672510] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/03/2021] [Indexed: 11/13/2022] Open
Abstract
During nuclear DNA replication multiprotein replisome machines have to jointly traverse and duplicate the total length of each chromosome during each cell cycle. At certain genomic locations replisomes encounter tight DNA-protein complexes and slow down. This fork pausing is an active process involving recognition of a protein barrier by the approaching replisome via an evolutionarily conserved Fork Pausing/Protection Complex (FPC). Action of the FPC protects forks from collapse at both programmed and accidental protein barriers, thus promoting genome integrity. In addition, FPC stimulates the DNA replication checkpoint and regulates topological transitions near the replication fork. Eukaryotic cells have been proposed to employ physiological programmed fork pausing for various purposes, such as maintaining copy number at repetitive loci, precluding replication-transcription encounters, regulating kinetochore assembly, or controlling gene conversion events during mating-type switching. Here we review the growing number of approaches used to study replication pausing in vivo and in vitro as well as the characterization of additional factors recently reported to modulate fork pausing in different systems. Specifically, we focus on the positive role of topoisomerases in fork pausing. We describe a model where replisome progression is inherently cautious, which ensures general preservation of fork stability and genome integrity but can also carry out specialized functions at certain loci. Furthermore, we highlight classical and novel outstanding questions in the field and propose venues for addressing them. Given how little is known about replisome pausing at protein barriers in human cells more studies are required to address how conserved these mechanisms are.
Collapse
Affiliation(s)
- Maksym Shyian
- Department of Molecular Biology, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| | - David Shore
- Department of Molecular Biology, Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
| |
Collapse
|
47
|
The S-Phase Cyclin Clb5 Promotes rRNA Gene (rDNA) Stability by Maintaining Replication Initiation Efficiency in rDNA. Mol Cell Biol 2021; 41:MCB.00324-20. [PMID: 33619126 PMCID: PMC8088266 DOI: 10.1128/mcb.00324-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 02/05/2021] [Indexed: 11/26/2022] Open
Abstract
Regulation of replication origins is important for complete duplication of the genome, but the effect of origin activation on the cellular response to replication stress is poorly understood. The budding yeast rRNA gene (rDNA) forms tandem repeats and undergoes replication fork arrest at the replication fork barrier (RFB), inducing DNA double-strand breaks (DSBs) and genome instability accompanied by copy number alterations. Regulation of replication origins is important for complete duplication of the genome, but the effect of origin activation on the cellular response to replication stress is poorly understood. The budding yeast rRNA gene (rDNA) forms tandem repeats and undergoes replication fork arrest at the replication fork barrier (RFB), inducing DNA double-strand breaks (DSBs) and genome instability accompanied by copy number alterations. Here, we demonstrate that the S-phase cyclin Clb5 promotes rDNA stability. Absence of Clb5 led to reduced efficiency of replication initiation in rDNA but had little effect on the number of replication forks arrested at the RFB, suggesting that arrival of the converging fork is delayed and forks are more stably arrested at the RFB. Deletion of CLB5 affected neither DSB formation nor its repair at the RFB but led to homologous recombination-dependent rDNA instability. Therefore, arrested forks at the RFB may be subject to DSB-independent, recombination-dependent rDNA instability. The rDNA instability in clb5Δ was not completely suppressed by the absence of Fob1, which is responsible for fork arrest at the RFB. Thus, Clb5 establishes the proper interval for active replication origins and shortens the travel distance for DNA polymerases, which may reduce Fob1-independent DNA damage.
Collapse
|
48
|
Ribeiro T, Nascimento J, Santos A, Félix LP, Guerra M. Origin and evolution of highly polymorphic rDNA sites in Alstroemeria longistaminea (Alstroemeriaceae) and related species. Genome 2021; 64:833-845. [PMID: 33852822 DOI: 10.1139/gen-2020-0159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Alstroemeria (Alstroemeriaceae) displays a conserved and highly asymmetric karyotype, where most rDNA sites can be properly recognized by the size and morphology of the chromosomes. We analyzed the intraspecific variation of rDNA sites in A. longistaminea and compared with their distribution in other species (A. caryophyllaea and A. piauhyensis) and a representative of a sister genus, Bomarea edulis. All three species of Alstroemeria presented 2n = 16, and one to six B chromosomes were found in some individuals of A. longistaminea. There was a set of 12 conserved rDNA sites (four 5S and eight 35S) and up to 11 variable sites. B chromosomes were almost entirely covered by 35S signals, coupled with tiny 5S sites. Noteworthy, most rDNA sites found in A. caryophyllaea and A. piauhyensis were localized in chromosome positions similar to those in A. longistaminea, suggesting the existence of conserved hotspots for rDNA accumulation. Some of these hotspots were absent in Chilean Alstromeria as well in B. edulis. We propose that insertions of rDNA sequences on chromosomes do not occur randomly but rather on preferential sites or hotspots for insertions. The maintenance of these arrays, however, may be favored/constrained by different factors, resulting in stable or polymorphic sites.
Collapse
Affiliation(s)
- Tiago Ribeiro
- Laboratório de Citogenética e Evolução Vegetal, Universidade Federal de Pernambuco, Departamento de Botânica, Recife, Pernambuco, Brasil
| | - Jéssica Nascimento
- Laboratório de Citogenética e Evolução Vegetal, Universidade Federal de Pernambuco, Departamento de Botânica, Recife, Pernambuco, Brasil
| | - Amanda Santos
- Laboratório de Citogenética e Evolução Vegetal, Universidade Federal de Pernambuco, Departamento de Botânica, Recife, Pernambuco, Brasil
| | - Leonardo P Félix
- Universidade Federal da Paraíba, Departamento de Biociências, Campus II, Areia, Paraíba, Brasil
| | - Marcelo Guerra
- Laboratório de Citogenética e Evolução Vegetal, Universidade Federal de Pernambuco, Departamento de Botânica, Recife, Pernambuco, Brasil
| |
Collapse
|
49
|
Overcoming the design, build, test bottleneck for synthesis of nonrepetitive protein-RNA cassettes. Nat Commun 2021; 12:1576. [PMID: 33707432 PMCID: PMC7952577 DOI: 10.1038/s41467-021-21578-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 01/20/2021] [Indexed: 01/03/2023] Open
Abstract
We apply an oligo-library and machine learning-approach to characterize the sequence and structural determinants of binding of the phage coat proteins (CPs) of bacteriophages MS2 (MCP), PP7 (PCP), and Qβ (QCP) to RNA. Using the oligo library, we generate thousands of candidate binding sites for each CP, and screen for binding using a high-throughput dose-response Sort-seq assay (iSort-seq). We then apply a neural network to expand this space of binding sites, which allowed us to identify the critical structural and sequence features for binding of each CP. To verify our model and experimental findings, we design several non-repetitive binding site cassettes and validate their functionality in mammalian cells. We find that the binding of each CP to RNA is characterized by a unique space of sequence and structural determinants, thus providing a more complete description of CP-RNA interaction as compared with previous low-throughput findings. Finally, based on the binding spaces we demonstrate a computational tool for the successful design and rapid synthesis of functional non-repetitive binding-site cassettes. Phage-coat proteins can be used to build synthetic biology parts. Here the authors use an oligo library and machine learning to predict and verify sequences based on binding scores.
Collapse
|
50
|
Yarimizu K, Sildever S, Hamamoto Y, Tazawa S, Oikawa H, Yamaguchi H, Basti L, Mardones JI, Paredes-Mella J, Nagai S. Development of an absolute quantification method for ribosomal RNA gene copy numbers per eukaryotic single cell by digital PCR. HARMFUL ALGAE 2021; 103:102008. [PMID: 33980448 DOI: 10.1016/j.hal.2021.102008] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
Recent increase of Harmful Algal Blooms (HAB) causes world-wide ecological, economical, and health issues, and more attention is paid to frequent coastal monitoring for the early detection of HAB species to prevent or reduce such impacts. Use of molecular tools in addition to traditional microscopy-based observation has become one of the promising methodologies for coastal monitoring. However, as ribosomal RNA (rRNA) genes are commonly targeted in molecular studies, variability in the rRNA gene copy number within and between species must be considered to provide quantitative information in quantitative PCR (qPCR), digital PCR (dPCR), and metabarcoding analyses. Currently, this information is only available for a limited number of species. The present study utilized a dPCR technology to quantify copy numbers of rRNA genes per single cell in 16 phytoplankton species, the majority of which are toxin-producers, using a newly developed universal primer set accompanied by a labeled probe with a fluorophore and a double-quencher. In silico PCR using the newly developed primers allowed the detection of taxa from 8 supergroups, demonstrating universality and broad coverage of the primer set. Chelex buffer was found to be suitable for DNA extraction to obtain DNA fragments with suitable size to avoid underestimation of the copy numbers. The study successfully demonstrated the first comparison of absolute quantification of 18S rRNA copy numbers per cell from 16 phytoplankton species by the dPCR technology.
Collapse
Affiliation(s)
- Kyoko Yarimizu
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan; Office of Industry-Academia-Government and Community Collaboration, Hiroshima University, 1-3-2 22 Kagamiyama, Higashi-Hiroshima City, Hiroshima 739-8511, Japan
| | - Sirje Sildever
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan; Department of Marine Systems, Tallinn University of Technology, Akadeemia tee 15A, 12618 Tallinn, Estonia
| | - Yoko Hamamoto
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan
| | - Satoshi Tazawa
- AXIOHELIX Co. Ltd, 12-17 Kandaizumicho, Chiyoda-ku, Tokyo 101-0024, Japan
| | - Hiroshi Oikawa
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan
| | - Haruo Yamaguchi
- Faculty of Agriculture and Marine Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Leila Basti
- Department of Ocean Sciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan
| | - Jorge I Mardones
- Instituto de Fomento Pesquero, Centro de Estudios de Algas Nocivas (IFOP-CREAN), Padre Harter 574, Puerto Montt 5501679, Chile; Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile
| | - Javier Paredes-Mella
- Instituto de Fomento Pesquero, Centro de Estudios de Algas Nocivas (IFOP-CREAN), Padre Harter 574, Puerto Montt 5501679, Chile
| | - Satoshi Nagai
- Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Fisheries Stock Assessment Center, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan.
| |
Collapse
|