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Zhou Y, Zhang H, Yan H, Han P, Zhang J, Liu Y. Deciphering the Role of Oxidative Stress in Male Infertility: Insights from Reactive Oxygen Species to Antioxidant Therapeutics. FRONT BIOSCI-LANDMRK 2025; 30:27046. [PMID: 40302329 DOI: 10.31083/fbl27046] [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: 10/20/2024] [Revised: 12/25/2024] [Accepted: 01/10/2025] [Indexed: 05/02/2025]
Abstract
Male infertility represents a major health concern, accounting for approximately 50% of all infertility cases in couples. This condition arises from multiple etiologies, with oxidative stress gaining increasing attention in recent studies. During the final stages of sperm maturation, the majority of the cytoplasm is discarded, leaving sperm with a diminished antioxidant defense system, which makes them highly susceptible to the detrimental effects of reactive oxygen species (ROS). ROS can be generated from both intrinsic and extrinsic sources. Intrinsically, ROS are primarily produced by mitochondrial activity, while extrinsic factors include alcohol consumption, smoking, circadian rhythm disruption, gut microbiota imbalance, and leukocyte infiltration. Excessive ROS production leads to DNA damage, apoptosis, and epigenetic modifications in sperm, ultimately impairing sperm motility and contributing to infertility. This review provides a comprehensive examination of ROS sources and examines the mechanisms by which ROS induce sperm damage. Furthermore, it explores the therapeutic potential of antioxidants in mitigating oxidative stress and improving sperm quality.
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Affiliation(s)
- Ye Zhou
- Department of Reproductive Medicine, Zhaotong Hospital of Traditional Chinese Medicine, 657000 Zhaotong, Yunnan, China
| | - Hengyan Zhang
- Department of Dermatology, Zhaotong Hospital of Traditional Chinese Medicine, 657000 Zhaotong, Yunnan, China
| | - Heguo Yan
- Department of Clinical Medicine, Yunnan University of Chinese Medicine, 650500 Kunming, Yunnan, China
- Department of Endocrinology, Zhaotong Hospital of Traditional Chinese Medicine, 657000 Zhaotong, Yunnan, China
| | - Pingxing Han
- Department of Reproductive Medicine, Zhaotong Hospital of Traditional Chinese Medicine, 657000 Zhaotong, Yunnan, China
| | - Jing Zhang
- Department of Reproductive Medicine, Zhaotong Hospital of Traditional Chinese Medicine, 657000 Zhaotong, Yunnan, China
| | - Yangwen Liu
- Department of Endocrinology, Zhaotong Hospital of Traditional Chinese Medicine, 657000 Zhaotong, Yunnan, China
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2
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Li B. Telomere maintenance in African trypanosomes. Front Mol Biosci 2023; 10:1302557. [PMID: 38074093 PMCID: PMC10704157 DOI: 10.3389/fmolb.2023.1302557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 02/12/2024] Open
Abstract
Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve a balance between stability and plasticity at telomere/subtelomere will help develop better means to eradicate human diseases caused by these pathogens. Telomere replication faces several challenges, and the "end replication problem" is a key obstacle that can cause progressive telomere shortening in proliferating cells. To overcome this challenge, most eukaryotes use telomerase to extend the G-rich telomere strand. In addition, a number of telomere proteins use sophisticated mechanisms to coordinate the telomerase-mediated de novo telomere G-strand synthesis and the telomere C-strand fill-in, which has been extensively studied in mammalian cells. However, we recently discovered that trypanosomes lack many telomere proteins identified in its mammalian host that are critical for telomere end processing. Rather, T. brucei uses a unique DNA polymerase, PolIE that belongs to the DNA polymerase A family (E. coli DNA PolI family), to coordinate the telomere G- and C-strand syntheses. In this review, I will first briefly summarize current understanding of telomere end processing in mammals. Subsequently, I will describe PolIE-mediated coordination of telomere G- and C-strand synthesis in T. brucei and implication of this recent discovery.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts and Sciences, Cleveland State University, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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3
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Choi BE, Lee HT. DNA-RNA hybrid G-quadruplex tends to form near the 3' end of telomere overhang. Biophys J 2022; 121:2962-2980. [PMID: 35769005 PMCID: PMC9388385 DOI: 10.1016/j.bpj.2022.06.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 01/14/2022] [Accepted: 06/24/2022] [Indexed: 11/25/2022] Open
Abstract
Telomeric repeat-containing RNA (TERRA) has been suggested to participate in telomere maintenance. TERRA consisting of UUAGGG repeats is capable of forming an intermolecular G-quadruplex (GQ) with single-stranded TTAGGG-repeat DNA in the telomere 3' overhang. To explore the structural features and potential functions of this DNA-RNA hybrid GQ (HGQ), we used single-molecule FRET to study the folding patterns of DNA with four to seven telomeric tandem repeats annealed with a short RNA consisting of two or five telomeric repeats. Our data highlight that RNA prefers to form DNA-RNA HGQ near the 3' end of telomeric DNA. Furthermore, the unfolding of secondary structures by a complementary C-rich sequence was observed for DNA GQ but not for DNA-RNA HGQ, which demonstrated the enhanced stability of the telomere 3' end via hybridization with RNA. These conformational and physical properties of telomeric DNA-RNA HGQ suggest that TERRA might limit access to the 3' end of the telomeric DNA overhang, which is known to be critical for the interaction with telomerase and other telomere-associated proteins.
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Affiliation(s)
- Bok-Eum Choi
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama
| | - Hui-Ting Lee
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama.
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Rabbani MAG, Tonini ML, Afrin M, Li B. POLIE suppresses telomerase-mediated telomere G-strand extension and helps ensure proper telomere C-strand synthesis in trypanosomes. Nucleic Acids Res 2022; 50:2036-2050. [PMID: 35061898 PMCID: PMC8887473 DOI: 10.1093/nar/gkac023] [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: 09/28/2021] [Revised: 01/05/2022] [Accepted: 01/07/2022] [Indexed: 11/15/2022] Open
Abstract
Trypanosoma brucei causes human African trypanosomiasis and sequentially expresses distinct VSGs, its major surface antigen, to achieve host immune evasion. VSGs are monoallelically expressed from subtelomeric loci, and telomere proteins regulate VSG monoallelic expression and VSG switching. T. brucei telomerase is essential for telomere maintenance, but no regulators of telomerase have been identified. T. brucei appears to lack OB fold-containing telomere-specific ssDNA binding factors that are critical for coordinating telomere G- and C-strand syntheses in higher eukaryotes. We identify POLIE as a telomere protein essential for telomere integrity. POLIE-depleted cells have more frequent VSG gene conversion-mediated VSG switching and an increased amount of telomeric circles (T-circles), indicating that POLIE suppresses DNA recombination at the telomere/subtelomere. POLIE-depletion elongates telomere 3' overhangs dramatically, indicating that POLIE is essential for coordinating DNA syntheses of the two telomere strands. POLIE depletion increases the level of telomerase-dependent telomere G-strand extension, identifying POLIE as the first T. brucei telomere protein that suppresses telomerase. Furthermore, depletion of POLIE results in an elevated telomeric C-circle level, suggesting that the telomere C-strand experiences replication stress and that POLIE may promote telomere C-strand synthesis. Therefore, T. brucei uses a novel mechanism to coordinate the telomere G- and C-strand DNA syntheses.
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Affiliation(s)
- M A G Rabbani
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Maiko Luis Tonini
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Marjia Afrin
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland OH 44195, USA
- Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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5
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Cui M, Bai Y, Li K, Rong YS. Taming active transposons at Drosophila telomeres: The interconnection between HipHop's roles in capping and transcriptional silencing. PLoS Genet 2021; 17:e1009925. [PMID: 34813587 PMCID: PMC8651111 DOI: 10.1371/journal.pgen.1009925] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/07/2021] [Accepted: 11/03/2021] [Indexed: 11/19/2022] Open
Abstract
Drosophila chromosomes are elongated by retrotransposon attachment, a process poorly understood. Here we characterized a mutation affecting the HipHop telomere-capping protein. In mutant ovaries and the embryos that they produce, telomere retrotransposons are activated and transposon RNP accumulates. Genetic results are consistent with that this hiphop mutation weakens the efficacy of HP1-mediated silencing while leaving piRNA-based mechanisms largely intact. Remarkably, mutant females display normal fecundity suggesting that telomere de-silencing is compatible with germline development. Moreover, unlike prior mutants with overactive telomeres, the hiphop stock does not over-accumulate transposons for hundreds of generations. This is likely due to the loss of HipHop’s abilities both to silence transcription and to recruit transposons to telomeres in the mutant. Furthermore, embryos produced by mutant mothers experience a checkpoint activation, and a further loss of maternal HipHop leads to end-to-end fusion and embryonic arrest. Telomeric retroelements fulfill an essential function yet maintain a potentially conflicting relationship with their Drosophila host. Our study thus showcases a possible intermediate in this arm race in which the host is adapting to over-activated transposons while maintaining genome stability. Our results suggest that the collapse of such a relationship might only occur when the selfish element acquires the ability to target non-telomeric regions of the genome. HipHop is likely part of this machinery restricting the elements to the gene-poor region of telomeres. Lastly, our hiphop mutation behaves as a recessive suppressor of PEV that is mediated by centric heterochromatin, suggesting its broader effect on chromatin not limited to telomeres. Transposons are selfish elements that multiply by inserting extra copies of themselves into the host genome. Active transposons thus threaten the stability of the host genome, while the host responses by transcriptionally silencing the selfish elements or targeting their insertions towards gene-poor regions of the genome. Chromosome ends (telomeres) in the fruit fly Drosophila are elongated by active transposition of retrotransposons. Although much is known about how these elements are silenced, little is known about the remarkable accuracy by which they are targeted to telomeres. Prime candidates through which the host mounts such defenses are members of the protein complexes that protect telomeres. Here we characterized a hypomorphic mutation of the HipHop protein, and showed that active telomeric transcription in the mutant germline persists for generations without leading to runaway telomere elongation, that embryos laid by the mutant female suffer rampant end-to-end fusions, and that telomeric targeting of the transposon machinery is defective in the mutant soma. Collectively our data suggest that HipHop is essential for preventing telomere fusions, silencing telomeric transposons, and recruiting transposon machinery to telomeres. Our study thus identifies a factor essential for the host control over active transposons and a paradigm for studying such control mechanisms.
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Affiliation(s)
- Min Cui
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Yaofu Bai
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Kaili Li
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Yikang S. Rong
- Hengyang College of Medicine, University of South China, Hengyang, China
- * E-mail:
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6
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Cowell W, Tang D, Yu J, Guo J, Wang S, Baccarelli AA, Perera F, Herbstman JB. Telomere dynamics across the early life course: Findings from a longitudinal study in children. Psychoneuroendocrinology 2021; 129:105270. [PMID: 34020264 PMCID: PMC8217283 DOI: 10.1016/j.psyneuen.2021.105270] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 01/07/2023]
Abstract
Telomeres are protective caps on chromosome ends that shorten with each cell division. Telomere length (TL) predicts the onset of cellular senescence and correlates with longevity and age-related disease risk. Previous research suggests that adults display fixed ranking and tracking of TL by age 20 years, supporting the importance of TL at birth and attrition during childhood. However, longitudinal research examining telomere dynamics during early life is sparse. Here, we used monochrome multiplex quantitative polymerase chain reaction to measure relative TL in leukocytes isolated from cord blood and child blood collected at ages 3, 5, 7, and 9 years among 224 minority children enrolled in a New York City-based birth cohort. We also measured maternal TL at delivery in a subset of 197 participants with a biobanked blood sample. TL decreased most rapidly in the first years of life (birth to 3 years), followed by a period of maintenance into the pre-puberty period. Mothers with longer telomeres gave birth to newborns with longer telomeres that remained longer across childhood, suggesting that the fixed ranking and tracking of TL observed among adults may extend to early childhood or even the prenatal period with a potential transgenerational basis. We did not find significant sex differences in the pattern of child TL change across development. These findings emphasize the need to understand factors and mechanisms that determine TL during early childhood.
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Affiliation(s)
- Whitney Cowell
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY 10128, USA.
| | - Deliang Tang
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Jie Yu
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Jia Guo
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Shuang Wang
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Andrea A Baccarelli
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Frederica Perera
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Julie B Herbstman
- Columbia Center for Children's Environmental Health, Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA; Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
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7
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Duan X, Hong J, Wang F, Wei K, Wang P, Hou F, Zhang M, Liu D, Yuan D, Liu S. The influence of ACYP2 polymorphisms on gastrointestinal cancer susceptibility in the Chinese Han population. Mol Genet Genomic Med 2019; 7:e00700. [PMID: 31070019 PMCID: PMC6625334 DOI: 10.1002/mgg3.700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/29/2019] [Accepted: 04/07/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Gastrointestinal cancer (GI cancer) is a type of cancer that has a high death rate. It has been reported that ACYP2 gene was associated with the development of gastric cancer and colorectal cancer, but it is not clear that the relationship between ACYP2 gene and GI cancer in Chinese Han population. This study aimed to investigate the association between polymorphisms of ACYP2 and GI cancer in the Chinese Han population. METHODS We used Agena MassARRAY to determine the genotypes of 1,160 GI cancer patients and 495 healthy controls. The correlation between ACYP2 variants and GI cancer risk was examined by logistic regression analysis. RESULTS We identified that rs6713088 (OR = 1.17, 95% CI: 1.00-1.36, p = 0.047), rs843711 (OR = 1.17, 95 CI: 1.01-1.36, p = 0.035), and rs11896604 (OR = 1.20, 95% CI: 1.00-1.45, p = 0.048) were correlated with an increased risk of GI cancer under allele model. Rs11125529 under the recessive model (OR = 2.05, 95% CI: 1.00-4.23, p = 0.038), rs843711 in recessive model (OR = 1.37, 95% CI: 1.04-1.82, p = 0.026), and rs11896604 under log-additive model (OR = 1.23, 95% CI: 1.01-1.51, p = 0.042) were associated with an increased risk of GI cancer. CONCLUSION Our study suggested that polymorphisms of ACYP2 gene might be associated with susceptibility to GI cancer.
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Affiliation(s)
- Xianglong Duan
- The Second Department of General SurgeryShaanxi Provincial People's HospitalXi'anChina
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of MedicineXizang Minzu UniversityXianyangChina
| | - Jiajing Hong
- College of Acupuncture and MassageChangchun University of Traditional Chinese MedicineChangchunChina
| | - Fuchun Wang
- Institute of Acupuncture and MassageChangchun University of Traditional Chinese MedicineChangchunChina
| | - Kun Wei
- Medical CollegeYan'an UniversityYan'anChina
| | - Pengyuan Wang
- Clinical Medical CollegeXi'an Medical UniversityXi'anChina
| | - Feng Hou
- Clinical Medical CollegeXi'an Medical UniversityXi'anChina
| | - Min Zhang
- Medical CollegeYan'an UniversityYan'anChina
| | - Dengfeng Liu
- Clinical Medical CollegeXi'an Medical UniversityXi'anChina
| | - Dongya Yuan
- Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of MedicineXizang Minzu UniversityXianyangChina
| | - Sida Liu
- The Second Department of General SurgeryShaanxi Provincial People's HospitalXi'anChina
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Monaghan P, Eisenberg DTA, Harrington L, Nussey D. Understanding diversity in telomere dynamics. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2016.0435. [PMID: 29335374 DOI: 10.1098/rstb.2016.0435] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2017] [Indexed: 12/13/2022] Open
Affiliation(s)
- Pat Monaghan
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Graham Kerr Building, Glasgow G12 8QQ, UK
| | - Dan T A Eisenberg
- Department of Anthropology, University of Washington, 314 Denny Hall, Box 353100 Seattle, WA 98195-3100, USA
| | - Lea Harrington
- Départemente de Médecine, Institut de recherche en immunologie et en cancérologie, Université de Montréal, 2950 chemin de Polytechnique, Montréal, Québec, Canada H3T 1J4
| | - Dan Nussey
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Labs, The King's Buildings, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
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Santana VP, Miranda-Furtado CL, Pedroso DCC, Eiras MC, Vasconcelos MAC, Ramos ES, Calado RT, Ferriani RA, Esteves SC, dos Reis RM. The relationship among sperm global DNA methylation, telomere length, and DNA fragmentation in varicocele: a cross-sectional study of 20 cases. Syst Biol Reprod Med 2019; 65:95-104. [DOI: 10.1080/19396368.2018.1557762] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Viviane Paiva Santana
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | - Daiana Cristina Chielli Pedroso
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Matheus Credendio Eiras
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | - Ester Silveira Ramos
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Rodrigo Tocantins Calado
- Department of Internal Medicine, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Rui Alberto Ferriani
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | - Rosana Maria dos Reis
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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Abstract
Dna2 is a nuclease and helicase that functions redundantly with other proteins in Okazaki fragment processing, double-strand break resection, and checkpoint kinase activation. Dna2 is an essential enzyme, required for yeast and mammalian cell viability. Here, we report that numerous mutations affecting the DNA damage checkpoint suppress dna2∆ lethality in Saccharomyces cerevisiaedna2∆ cells are also suppressed by deletion of helicases PIF1 and MPH1, and by deletion of POL32, a subunit of DNA polymerase δ. All dna2∆ cells are temperature sensitive, have telomere length defects, and low levels of telomeric 3' single-stranded DNA (ssDNA). Interestingly, Rfa1, a subunit of the major ssDNA binding protein RPA, and the telomere-specific ssDNA binding protein Cdc13, often colocalize in dna2∆ cells. This suggests that telomeric defects often occur in dna2∆ cells. There are several plausible explanations for why the most critical function of Dna2 is at telomeres. Telomeres modulate the DNA damage response at chromosome ends, inhibiting resection, ligation, and cell-cycle arrest. We suggest that Dna2 nuclease activity contributes to modulating the DNA damage response at telomeres by removing telomeric C-rich ssDNA and thus preventing checkpoint activation.
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11
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Cowell WJ, Wright RJ. Sex-Specific Effects of Combined Exposure to Chemical and Non-chemical Stressors on Neuroendocrine Development: a Review of Recent Findings and Putative Mechanisms. Curr Environ Health Rep 2018; 4:415-425. [PMID: 29027649 DOI: 10.1007/s40572-017-0165-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PURPOSE OF REVIEW Environmental toxicants and psychosocial stressors share many biological substrates and influence overlapping physiological pathways. Increasing evidence indicates stress-induced changes to the maternal milieu may prime rapidly developing physiological systems for disruption by concurrent or subsequent exposure to environmental chemicals. In this review, we highlight putative mechanisms underlying sex-specific susceptibility of the developing neuroendocrine system to the joint effects of stress or stress correlates and environmental toxicants (bisphenol A, alcohol, phthalates, lead, chlorpyrifos, and traffic-related air pollution). RECENT FINDINGS We provide evidence indicating that concurrent or tandem exposure to chemical and non-chemical stressors during windows of rapid development is associated with sex-specific synergistic, potentiated and reversed effects on several neuroendocrine endpoints related to hypothalamic-pituitary-adrenal axis function, sex steroid levels, neurotransmitter circuits, and innate immune function. We additionally identify gaps, such as the role that the endocrine-active placenta plays, in our understanding of these complex interactions. Finally, we discuss future research needs, including the investigation of non-hormonal biomarkers of stress. We demonstrate multiple physiologic systems are impacted by joint exposure to chemical and non-chemical stressors differentially among males and females. Collectively, the results highlight the importance of evaluating sex-specific endpoints when investigating the neuroendocrine system and underscore the need to examine exposure to chemical toxicants within the context of the social environment.
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Affiliation(s)
- Whitney J Cowell
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA. .,Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, 12th Floor, Mailman School of Public Health, 722 West 168th St, New York, NY, 10032, USA.
| | - Rosalind J Wright
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Institute for Exposomic Research, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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12
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Cheng L, Cui M, Rong YS. MTV sings jubilation for telomere biology in Drosophila. Fly (Austin) 2018; 12:41-45. [PMID: 28471262 PMCID: PMC5927694 DOI: 10.1080/19336934.2017.1325979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 04/28/2017] [Indexed: 02/08/2023] Open
Abstract
Telomere protects the ends of linear chromosomes. Telomere dysfunction fuels genome instability that can lead to diseases such as cancer. For over 30 years, Drosophila has fascinated the field as the only major model organism that does not rely on the conserved telomerase enzyme for end protection. Instead of short DNA repeats at chromosome ends, Drosophila has domesticated retrotransposons. In addition, telomere protection can be entirely sequence-independent under normal laboratory conditions, again dissimilar to what has been established for telomerase-maintained systems. Despite these major differences, recent studies from us and others have revealed remarkable similarities between the 2 systems. In particular, with the identification of the MTV complex as an ssDNA binding complex essential for telomere integrity in Drosophila (Zhang et al. 2016 Plos Genetics), we have now established several universal principles that are intrinsic to chromosome extremities but independent of the underlying DNA sequences or the telomerase enzyme. Telomere studies in Drosophila will continue to yield fundamental insights that are instrumental to the understanding of the evolution of telomere and telomeric functions.
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Affiliation(s)
- Lin Cheng
- School of life Sciences, State Key Laboratory of Bio-control, Sun Yat-sen University, Guangzhou, China
| | - Ming Cui
- School of life Sciences, State Key Laboratory of Bio-control, Sun Yat-sen University, Guangzhou, China
| | - Yikang S. Rong
- School of life Sciences, State Key Laboratory of Bio-control, Sun Yat-sen University, Guangzhou, China
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13
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Abstract
Telomere length is maintained in most eukaryotes by the action of a specialized enzyme, the telomerase. However, the complexity of mechanisms regulating telomeric DNA length as well as the heterogeneity in length of each telomere in a population of cells has made it very difficult to understand how telomerase is regulated in vivo. Here, we describe a method developed in Saccharomyces cerevisiae to monitor the addition of telomeric sequences to a single newly generated telomere in vivo. The primary strain consists of a HO endonuclease cleavage site that is placed directly adjacent to an 81-base-pair stretch of telomeric DNA inserted into the ADH4 locus of chromosome VII. Upon cleavage by HO, the de novo DNA end is rapidly healed by the telomerase enzyme and the analysis of this process allows to gain a mechanistic understanding of how telomerase action is regulated in the cell.
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Affiliation(s)
- Diego Bonetti
- Institute for Molecular Biology (IMB) gGMBH, Ackermannweg 4, 55128, Mainz, Germany.
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy.
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
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14
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Telomerase activity is required for the telomere G-overhang structure in Trypanosoma brucei. Sci Rep 2017; 7:15983. [PMID: 29167542 PMCID: PMC5700094 DOI: 10.1038/s41598-017-16182-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/08/2017] [Indexed: 01/24/2023] Open
Abstract
Trypanosoma brucei causes fatal human African trypanosomiasis and evades the host immune response by regularly switching its major surface antigen, VSG, which is expressed exclusively from subtelomeric loci. Telomere length and telomere proteins play important roles in regulating VSG silencing and switching. T. brucei telomerase plays a key role in maintaining telomere length, and T. brucei telomeres terminate in a single-stranded 3′ G-rich overhang. Understanding the detailed structure of the telomere G-overhang and its maintenance will contribute greatly to better understanding telomere maintenance mechanisms. Using an optimized adaptor ligation assay, we found that most T. brucei telomere G-overhangs end in 5′ TTAGGG 3′, while a small portion of G-overhangs end in 5′ TAGGGT 3′. Additionally, the protein and the RNA components of the telomerase (TbTERT and TbTR) and TbKu are required for telomere G-overhangs that end in 5′ TTAGGG 3′ but do not significantly affect the 5′ TAGGGT 3′-ending overhangs, indicating that telomerase-mediated telomere synthesis is important for the telomere G-overhang structure. Furthermore, using telomere oligo ligation-mediated PCR, we showed for the first time that the T. brucei telomere 5′ end sequence – an important feature of the telomere terminal structure – is not random but preferentially 5′ CCTAAC 3′.
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15
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Cesena D, Cassani C, Rizzo E, Lisby M, Bonetti D, Longhese MP. Regulation of telomere metabolism by the RNA processing protein Xrn1. Nucleic Acids Res 2017; 45:3860-3874. [PMID: 28160602 PMCID: PMC5397203 DOI: 10.1093/nar/gkx072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 01/23/2017] [Accepted: 01/25/2017] [Indexed: 11/19/2022] Open
Abstract
Telomeric DNA consists of repetitive G-rich sequences that terminate with a 3΄-ended single stranded overhang (G-tail), which is important for telomere extension by telomerase. Several proteins, including the CST complex, are necessary to maintain telomere structure and length in both yeast and mammals. Emerging evidence indicates that RNA processing factors play critical, yet poorly understood, roles in telomere metabolism. Here, we show that the lack of the RNA processing proteins Xrn1 or Rrp6 partially bypasses the requirement for the CST component Cdc13 in telomere protection by attenuating the activation of the DNA damage checkpoint. Xrn1 is necessary for checkpoint activation upon telomere uncapping because it promotes the generation of single-stranded DNA. Moreover, Xrn1 maintains telomere length by promoting the association of Cdc13 to telomeres independently of ssDNA generation and exerts this function by downregulating the transcript encoding the telomerase inhibitor Rif1. These findings reveal novel roles for RNA processing proteins in the regulation of telomere metabolism with implications for genome stability in eukaryotes.
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Affiliation(s)
- Daniele Cesena
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan 20126, Italy
| | - Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan 20126, Italy
| | - Emanuela Rizzo
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan 20126, Italy
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Diego Bonetti
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan 20126, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan 20126, Italy
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16
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Kyriakou D, Stavrou E, Demosthenous P, Angelidou G, San Luis BJ, Boone C, Promponas VJ, Kirmizis A. Functional characterisation of long intergenic non-coding RNAs through genetic interaction profiling in Saccharomyces cerevisiae. BMC Biol 2016; 14:106. [PMID: 27927215 PMCID: PMC5142380 DOI: 10.1186/s12915-016-0325-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/09/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Transcriptome studies have revealed that many eukaryotic genomes are pervasively transcribed producing numerous long non-coding RNAs (lncRNAs). However, only a few lncRNAs have been ascribed a cellular role thus far, with most regulating the expression of adjacent genes. Even less lncRNAs have been annotated as essential hence implying that the majority may be functionally redundant. Therefore, the function of lncRNAs could be illuminated through systematic analysis of their synthetic genetic interactions (GIs). RESULTS Here, we employ synthetic genetic array (SGA) in Saccharomyces cerevisiae to identify GIs between long intergenic non-coding RNAs (lincRNAs) and protein-coding genes. We first validate this approach by demonstrating that the telomerase RNA TLC1 displays a GI network that corresponds to its well-described function in telomere length maintenance. We subsequently performed SGA screens on a set of uncharacterised lincRNAs and uncover their connection to diverse cellular processes. One of these lincRNAs, SUT457, exhibits a GI profile associating it to telomere organisation and we consistently demonstrate that SUT457 is required for telomeric overhang homeostasis through an Exo1-dependent pathway. Furthermore, the GI profile of SUT457 is distinct from that of its neighbouring genes suggesting a function independent to its genomic location. Accordingly, we show that ectopic expression of this lincRNA suppresses telomeric overhang accumulation in sut457Δ cells assigning a trans-acting role for SUT457 in telomere biology. CONCLUSIONS Overall, our work proposes that systematic application of this genetic approach could determine the functional significance of individual lncRNAs in yeast and other complex organisms.
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Affiliation(s)
- Dimitris Kyriakou
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | - Emmanouil Stavrou
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | | | - Georgia Angelidou
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | - Bryan-Joseph San Luis
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada
| | - Charles Boone
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada
| | - Vasilis J Promponas
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | - Antonis Kirmizis
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus.
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MTV, an ssDNA Protecting Complex Essential for Transposon-Based Telomere Maintenance in Drosophila. PLoS Genet 2016; 12:e1006435. [PMID: 27835648 PMCID: PMC5105952 DOI: 10.1371/journal.pgen.1006435] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/20/2016] [Indexed: 12/25/2022] Open
Abstract
Multiple complexes protect telomeres. In telomerase-maintained organisms, Shelterin related complexes occupy the duplex region while the CST and Tpp1-Pot1 complexes bind the single stranded overhang of telomeres. Drosophila uses a transposon-based mechanism for end protection. We showed that the HOAP-HipHop complex occupies the duplex region. Whether an ssDNA-binding complex exists is not known. Here we discover a novel protein, Tea, that is specifically enriched at telomeres to prevent telomere fusion. We also identify a complex consisting of Tea and two known capping proteins, Ver and Moi. The Moi-Tea-Ver (MTV) complex purified in vitro binds and protects ssDNA in a sequence-independent manner. Tea recruits Ver and Moi to telomeres, and point mutations disrupting MTV interaction in vitro result in telomere uncapping, consistent with these proteins functioning as a complex in vivo. MTV thus shares functional similarities with CST or TPP1-POT1 in protecting ssDNA, highlighting a conserved feature in end protecting mechanisms. Chromosome ends are protected by the telomere structure maintained by the telomerase enzyme in most organisms. The fruit fly Drosophila has fascinated the field as the only major model organism that relies solely on a telomerase-independent mechanism for end protection. The fly model is arguably the best system to reveal the most basic features of the telomere. Here we characterize the MTV complex in flies and suggest that MTV fulfills similar function as the ssDNA-binding complexes in other organisms. This is striking considering that MTV subunits display highly accelerated rates of protein evolution. Our findings will be of interest to scientists interested in the molecular mechanisms of telomere protection and evolution biologists interested in how telomere and telomeric functions evolve.
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18
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Lloyd NR, Dickey TH, Hom RA, Wuttke DS. Tying up the Ends: Plasticity in the Recognition of Single-Stranded DNA at Telomeres. Biochemistry 2016; 55:5326-40. [PMID: 27575340 PMCID: PMC5656232 DOI: 10.1021/acs.biochem.6b00496] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Telomeres terminate nearly exclusively in single-stranded DNA (ssDNA) overhangs comprised of the G-rich 3' end. This overhang varies widely in length from species to species, ranging from just a few bases to several hundred nucleotides. These overhangs are not merely a remnant of DNA replication but rather are the result of complex further processing. Proper management of the telomeric overhang is required both to deter the action of the DNA damage machinery and to present the ends properly to the replicative enzyme telomerase. This Current Topic addresses the biochemical and structural features used by the proteins that manage these variable telomeric overhangs. The Pot1 protein tightly binds the single-stranded overhang, preventing DNA damage sensors from binding. Pot1 also orchestrates the access of telomerase to that same substrate. The remarkable plasticity of the binding interface exhibited by the Schizosaccharomyces pombe Pot1 provides mechanistic insight into how these roles may be accomplished, and disease-associated mutations clustered around the DNA-binding interface in the hPOT1 highlight the importance of this function. The budding yeast Cdc13-Stn1-Ten1, a telomeric RPA complex closely associated with telomere function, also interacts with ssDNA in a fashion that allows degenerate sequences to be recognized. A related human complex composed of hCTC1, hSTN1, and hTEN1 has recently emerged with links to both telomere maintenance and general DNA replication and also exhibits mutations associated with telomere pathologies. Overall, these sequence-specific ssDNA binders exhibit a range of recognition properties that allow them to perform their unique biological functions.
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Affiliation(s)
- Neil R. Lloyd
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | | | - Robert A. Hom
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S. Wuttke
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
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19
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Lustig AJ. Hypothesis: Paralog Formation from Progenitor Proteins and Paralog Mutagenesis Spur the Rapid Evolution of Telomere Binding Proteins. Front Genet 2016; 7:10. [PMID: 26904098 PMCID: PMC4748036 DOI: 10.3389/fgene.2016.00010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/22/2016] [Indexed: 12/31/2022] Open
Abstract
Through elegant studies in fungal cells and complex organisms, we propose a unifying paradigm for the rapid evolution of telomere binding proteins (TBPs) that associate with either (or both) telomeric DNA and telomeric proteins. TBPs protect and regulate telomere structure and function. Four critical factors are involved. First, TBPs that commonly bind to telomeric DNA include the c-Myb binding proteins, OB-fold single-stranded binding proteins, and G-G base paired Hoogsteen structure (G4) binding proteins. Each contributes independently or, in some cases, cooperatively, to provide a minimum level of telomere function. As a result of these minimal requirements and the great abundance of homologs of these motifs in the proteome, DNA telomere-binding activity may be generated more easily than expected. Second, telomere dysfunction gives rise to genome instability, through the elevation of recombination rates, genome ploidy, and the frequency of gene mutations. The formation of paralogs that diverge from their progenitor proteins ultimately can form a high frequency of altered TBPs with altered functions. Third, TBPs that assemble into complexes (e.g., mammalian shelterin) derive benefits from the novel emergent functions. Fourth, a limiting factor in the evolution of TBP complexes is the formation of mutually compatible interaction surfaces amongst the TBPs. These factors may have different degrees of importance in the evolution of different phyla, illustrated by the apparently simpler telomeres in complex plants. Selective pressures that can utilize the mechanisms of paralog formation and mutagenesis to drive TBP evolution along routes dependent on the requisite physiologic changes.
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Affiliation(s)
- Arthur J Lustig
- Department of Biochemistry and Molecular Biology, Tulane University, New Orleans LA, USA
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20
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Fission Yeast Exo1 and Rqh1-Dna2 Redundantly Contribute to Resection of Uncapped Telomeres. PLoS One 2015; 10:e0140456. [PMID: 26465752 PMCID: PMC4605587 DOI: 10.1371/journal.pone.0140456] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 09/25/2015] [Indexed: 01/01/2023] Open
Abstract
The uncapping of telomeres induces a DNA damage response. In Schizosaccharomyces pombe, deletion of pot1+ causes telomere uncapping and rapid telomere resection, resulting in chromosome fusion. Using the nmt-pot1-aid strain, we previously reported that Pot1 shut-off causes telomere loss and chromosome fusion in S. pombe. However, the factors responsible for the resection of uncapped telomeres remain unknown. In this study, we investigated these factors and found that concomitant deletion of rqh1+ and exo1+ alleviated the loss of telomeres following Pot1 shut-off, suggesting that Rqh1 and Exo1 are redundantly involved in the resection of uncapped telomeres. We also investigated the role of Rqh1 helicase activity and found it to be essential for the resection of uncapped telomeres. Moreover, we found that Dna2 and Exo1 function redundantly in the resection of uncapped telomeres. Taken together, these results suggest that Exo1 and Rqh1-Dna2 redundantly contribute to the resection of uncapped telomeres. Therefore, our results demonstrate that nmt-pot1-aid is an important model strain to study the role of helicases and nucleases in the resection of uncapped telomeres and to improve our understanding of DNA double-strand break repair.
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21
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Hoffmann RF, Moshkin YM, Mouton S, Grzeschik NA, Kalicharan RD, Kuipers J, Wolters AHG, Nishida K, Romashchenko AV, Postberg J, Lipps H, Berezikov E, Sibon OCM, Giepmans BNG, Lansdorp PM. Guanine quadruplex structures localize to heterochromatin. Nucleic Acids Res 2015; 44:152-63. [PMID: 26384414 PMCID: PMC4705689 DOI: 10.1093/nar/gkv900] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/21/2015] [Indexed: 12/27/2022] Open
Abstract
Increasing amounts of data support a role for guanine quadruplex (G4) DNA and RNA structures in various cellular processes. We stained different organisms with monoclonal antibody 1H6 specific for G4 DNA. Strikingly, immuno-electron microscopy showed exquisite specificity for heterochromatin. Polytene chromosomes from Drosophila salivary glands showed bands that co-localized with heterochromatin proteins HP1 and the SNF2 domain-containing protein SUUR. Staining was retained in SUUR knock-out mutants but lost upon overexpression of SUUR. Somatic cells in Macrostomum lignano were strongly labeled, but pluripotent stem cells labeled weakly. Similarly, germline stem cells in Drosophila ovaries were weakly labeled compared to most other cells. The unexpected presence of G4 structures in heterochromatin and the difference in G4 staining between somatic cells and stem cells with germline DNA in ciliates, flatworms, flies and mammals point to a conserved role for G4 structures in nuclear organization and cellular differentiation.
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Affiliation(s)
- Roland F Hoffmann
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Yuri M Moshkin
- Department of Biochemistry, Erasmus University Medical Center, Dr. Molewaterplein 50, NL-3015 GE Rotterdam, The Netherlands
| | - Stijn Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Nicola A Grzeschik
- Department of Cell Biology, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Ruby D Kalicharan
- Department of Cell Biology, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Jeroen Kuipers
- Department of Cell Biology, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Anouk H G Wolters
- Department of Cell Biology, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Kazuki Nishida
- Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Aleksander V Romashchenko
- Department of Biochemistry, Erasmus University Medical Center, Dr. Molewaterplein 50, NL-3015 GE Rotterdam, The Netherlands Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Jan Postberg
- Helios Medical Centre Wuppertal, Paediatrics Centre, Witten/Herdecke University, Wuppertal, Germany
| | - Hans Lipps
- Institute of Cell Biology, Centre for Biomedical Education and Research, Witten/Herdecke University, Witten, Germany
| | - Eugene Berezikov
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Ody C M Sibon
- Department of Cell Biology, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Ben N G Giepmans
- Department of Cell Biology, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands
| | - Peter M Lansdorp
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, NL-9713 AV Groningen, The Netherlands Terry Fox Laboratory, British Columbia Cancer Agency and Department of Medicine, University of British Columbia Vancouver, BC, V5Z 1L3, Canada
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22
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Singh AK, Lakhotia SC. The hnRNP A1 homolog Hrb87F/Hrp36 is important for telomere maintenance in Drosophila melanogaster. Chromosoma 2015; 125:373-88. [PMID: 26373285 DOI: 10.1007/s00412-015-0540-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/25/2015] [Accepted: 09/07/2015] [Indexed: 10/23/2022]
Abstract
Unlike the telomerase-dependent mammalian telomeres, HeT-A, TART, and TAHRE (HTT) retroposon arrays regulate Drosophila telomere length. Cap prevents telomeric associations (TAs) and telomeric fusions (TFs). Our results suggest important roles of Hrb87F in telomeric HTT array and cap maintenance in Drosophila. All chromosome arms, except 2L, in Df(3R)Hrb87F homozygotes (Hrb87F-null) displayed significantly elongated telomeres with amplified HTT arrays and high TAs, all of which resolved without damage. Presence of FLAG-tagged Hrb87F (FLAG-Hrb87F) on cap and subtelomeric regions following hsFLAG-Hrb87F transgene expression in Df(3R)Hrb87F homozygotes suppressed TAs without affecting telomere length. A normal X-chromosome telomere expanded within five generations in Hrb87F-null background and displayed high TAs, but not when hsFLAG-Hrb87F was co-expressed. Tel (1) /Gaiano line or HP1 loss-of-function mutant-derived expanded telomeres carry Hrb87F on cap and HTT arrays while Hrb87F-null telomeres have HP1 and HOAP on caps and expanded HTT arrays. ISWI, seen only on cap on normal telomeres, was abundant on Hrb87F-null expanded HTT arrays. Extended telomeres derived from Tel (1) (Gaiano) or HP1-null mutation background interact with those from Hrb87F-null, since while the end association frequency was negligible in Df(3R)Hrb87F/+ nuclei, it increased significantly in co-presence of Tel (1) or HP1-null-based expanded telomere/s. Together, these suggest complex interactions between members of the proteome of telomere so that absence of any key member leads to telomere expansion and/or enhanced TAs/TFs. HTT expansion in Hrb87F-null condition is not developmental but a germline event presumably because absence of Hrb87F in germline may deregulate HTT retroposition/replication leading to telomere elongation.
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Affiliation(s)
- Anand K Singh
- Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, 221005, India
| | - Subhash C Lakhotia
- Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, 221005, India.
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23
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Robles-Espinoza CD, Velasco-Herrera MDC, Hayward NK, Adams DJ. Telomere-regulating genes and the telomere interactome in familial cancers. Mol Cancer Res 2015; 13:211-22. [PMID: 25244922 PMCID: PMC4278843 DOI: 10.1158/1541-7786.mcr-14-0305] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Telomeres are repetitive sequence structures at the ends of linear chromosomes that consist of double-stranded DNA repeats followed by a short single-stranded DNA protrusion. Telomeres need to be replicated in each cell cycle and protected from DNA-processing enzymes, tasks that cells execute using specialized protein complexes such as telomerase (that includes TERT), which aids in telomere maintenance and replication, and the shelterin complex, which protects chromosome ends. These complexes are also able to interact with a variety of other proteins, referred to as the telomere interactome, to fulfill their biological functions and control signaling cascades originating from telomeres. Given their essential role in genomic maintenance and cell-cycle control, germline mutations in telomere-regulating proteins and their interacting partners have been found to underlie a variety of diseases and cancer-predisposition syndromes. These syndromes can be characterized by progressively shortening telomeres, in which carriers can present with organ failure due to stem cell senescence among other characteristics, or can also present with long or unprotected telomeres, providing an alternative route for cancer formation. This review summarizes the critical roles that telomere-regulating proteins play in cell-cycle control and cell fate and explores the current knowledge on different cancer-predisposing conditions that have been linked to germline defects in these proteins and their interacting partners.
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Affiliation(s)
| | | | - Nicholas K Hayward
- Oncogenomics Laboratory, QIMR Berghofer Medical Research Institute, Herston, Brisbane, Queensland, Australia
| | - David J Adams
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
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24
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Abstract
Telomeres are the physical ends of eukaryotic linear chromosomes. Telomeres form special structures that cap chromosome ends to prevent degradation by nucleolytic attack and to distinguish chromosome termini from DNA double-strand breaks. With few exceptions, telomeres are composed primarily of repetitive DNA associated with proteins that interact specifically with double- or single-stranded telomeric DNA or with each other, forming highly ordered and dynamic complexes involved in telomere maintenance and length regulation. In proliferative cells and unicellular organisms, telomeric DNA is replicated by the actions of telomerase, a specialized reverse transcriptase. In the absence of telomerase, some cells employ a recombination-based DNA replication pathway known as alternative lengthening of telomeres. However, mammalian somatic cells that naturally lack telomerase activity show telomere shortening with increasing age leading to cell cycle arrest and senescence. In another way, mutations or deletions of telomerase components can lead to inherited genetic disorders, and the depletion of telomeric proteins can elicit the action of distinct kinases-dependent DNA damage response, culminating in chromosomal abnormalities that are incompatible with life. In addition to the intricate network formed by the interrelationships among telomeric proteins, long noncoding RNAs that arise from subtelomeric regions, named telomeric repeat-containing RNA, are also implicated in telomerase regulation and telomere maintenance. The goal for the next years is to increase our knowledge about the mechanisms that regulate telomere homeostasis and the means by which their absence or defect can elicit telomere dysfunction, which generally results in gross genomic instability and genetic diseases.
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