1
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Guan Y, He H, Guo Y, Zhang L. Essential roles of Rad6 in conidial property, stress tolerance, and pathogenicity of Beauveria bassiana. Virulence 2024; 15:2362748. [PMID: 38860453 PMCID: PMC11174126 DOI: 10.1080/21505594.2024.2362748] [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] [Received: 01/12/2024] [Accepted: 05/28/2024] [Indexed: 06/12/2024] Open
Abstract
Rad6 functions as a ubiquitin-conjugating protein that regulates cellular processes in many fungal species. However, its role in filamentous entomopathogenic fungi remains poorly understood. This study characterizes Rad6 in Beauveria bassiana, a filamentous fungus widely employed as a critical fungicide globally. The results demonstrate a significant association between Rad6 and conidial properties, heat shock response, and UV-B tolerance. Concurrently, the mutant strain exhibited heightened sensitivity to oxidative stress, cell wall interfering agents, DNA damage stress, and prolonged heat shock. Furthermore, the absence of Rad6 significantly extended the median lethal time (LT50) of Galleria mellonella infected by B. bassiana. This delay could be attributed to reduced Pr1 proteases and extracellular cuticle-degrading enzymes, diminished dimorphic transition rates, and dysregulated antioxidant enzymes. Additionally, the absence of Rad6 had a more pronounced effect on genetic information processing, metabolism, and cellular processes under normal conditions. However, its impact was limited to metabolism in oxidative stress. This study offers a comprehensive understanding of the pivotal roles of Rad6 in conidial and hyphal stress tolerance, environmental adaptation, and the pathogenesis of Beauveria bassiana.
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Affiliation(s)
- Yi Guan
- Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fuzhou, Fujian, China
| | - Haomin He
- Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fuzhou, Fujian, China
| | - Yuhan Guo
- Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fuzhou, Fujian, China
| | - Longbin Zhang
- Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fuzhou, Fujian, China
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2
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Hu C, Zhu XT, He MH, Shao Y, Qin Z, Wu ZJ, Zhou JQ. Elimination of subtelomeric repeat sequences exerts little effect on telomere essential functions in Saccharomyces cerevisiae. eLife 2024; 12:RP91223. [PMID: 38656297 DOI: 10.7554/elife.91223] [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] [Indexed: 04/26/2024] Open
Abstract
Telomeres, which are chromosomal end structures, play a crucial role in maintaining genome stability and integrity in eukaryotes. In the baker's yeast Saccharomyces cerevisiae, the X- and Y'-elements are subtelomeric repetitive sequences found in all 32 and 17 telomeres, respectively. While the Y'-elements serve as a backup for telomere functions in cells lacking telomerase, the function of the X-elements remains unclear. This study utilized the S. cerevisiae strain SY12, which has three chromosomes and six telomeres, to investigate the role of X-elements (as well as Y'-elements) in telomere maintenance. Deletion of Y'-elements (SY12YΔ), X-elements (SY12XYΔ+Y), or both X- and Y'-elements (SY12XYΔ) did not impact the length of the terminal TG1-3 tracks or telomere silencing. However, inactivation of telomerase in SY12YΔ, SY12XYΔ+Y, and SY12XYΔ cells resulted in cellular senescence and the generation of survivors. These survivors either maintained their telomeres through homologous recombination-dependent TG1-3 track elongation or underwent microhomology-mediated intra-chromosomal end-to-end joining. Our findings indicate the non-essential role of subtelomeric X- and Y'-elements in telomere regulation in both telomerase-proficient and telomerase-null cells and suggest that these elements may represent remnants of S. cerevisiae genome evolution. Furthermore, strains with fewer or no subtelomeric elements exhibit more concise telomere structures and offer potential models for future studies in telomere biology.
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Affiliation(s)
- Can Hu
- The 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, Shanghai, China
| | - Xue-Ting Zhu
- The 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, Shanghai, China
| | - Ming-Hong He
- The 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, Shanghai, China
| | - Yangyang Shao
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Zhongjun Qin
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Zhi-Jing Wu
- The 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, Shanghai, China
- Key Laboratory of Systems Health Science of Zhejiang Province, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
| | - Jin-Qiu Zhou
- The 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, Shanghai, China
- Key Laboratory of Systems Health Science of Zhejiang Province, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China
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3
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Luo XC, Yu L, Xu SY, Ying SH, Feng MG. Rad6, a ubiquitin conjugator required for insect-pathogenic lifestyle, UV damage repair, and genomic expression of Beauveria bassiana. Microbiol Res 2024; 281:127622. [PMID: 38246123 DOI: 10.1016/j.micres.2024.127622] [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] [Received: 10/30/2023] [Revised: 11/09/2023] [Accepted: 01/13/2024] [Indexed: 01/23/2024]
Abstract
The E2 ubiquitin conjugator Rad6 is required for DNA damage bypass in budding yeast but remain functionally unknown in filamentous fungi. Here, we report pleiotropic effect of Rad6 ortholog in Beauveria bassiana, a wide-spectrum fungal insecticide. Global ubiquitination signal was greatly attenuated in the absence of rad6. The blocked ubiquitination led to severe growth defect, blocked asexual development, and abolished infectivity/insect pathogenicity, which correlated with compromised conidial quality (including viability, hydrophobicity, adherence to insect cuticle, and thermotolerance) and blocked secretion of cuticle-degrading enzymes including Pr1 family proteases. Importantly, Rad6 played much greater role in photoreactivation of UVB-impaired conidia by a 3- or 5-h light plus 9- or 7-h dark incubation than in dark reactivation of those impaired conidia by a 12-h dark incubation. The high activity of Rad6 in photoreactivation in vivo was derived from its link to a protein complex cored by the photolyase regulators WC1 and WC2 via the strong interactions of Rad6 with the E3 partner Rad18 and Rad18 with WC2 revealed in yeast two-hybrid assays. Transcriptomic analysis resulted in identification of 2700 differentially regulated genes involved in various function categories and metabolism pathways, indicating a regulatory role of Rad6-mediated ubiquitination in gene expression networks and genomic stability. Conclusively, Rad6 is required for asexual and insect-pathogenic lifecycles, solar UV damage repair, and genomic expression of B. bassiana. The primary dependence of its strong anti-UV role on photoreactivation in vivo unveils a scenario distinct from the core role of its yeast ortholog in DNA damage bypass.
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Affiliation(s)
- Xin-Cheng Luo
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Lei Yu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Si-Yuan Xu
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Sheng-Hua Ying
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ming-Guang Feng
- Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
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4
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Das A, Giri AK, Bhattacharjee P. Targeting 'histone mark': Advanced approaches in epigenetic regulation of telomere dynamics in cancer. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195007. [PMID: 38237857 DOI: 10.1016/j.bbagrm.2024.195007] [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: 08/01/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/23/2024]
Abstract
Telomere integrity is required for the maintenance of genome stability and prevention of oncogenic transformation of cells. Recent evidence suggests the presence of epigenetic modifications as an important regulator of mammalian telomeres. Telomeric and subtelomeric regions are rich in epigenetic marks that regulate telomere length majorly through DNA methylation and post-translational histone modifications. Specific histone modifying enzymes play an integral role in establishing telomeric histone codes necessary for the maintenance of structural integrity. Alterations of crucial histone moieties and histone modifiers cause deregulations in the telomeric chromatin leading to carcinogenic manifestations. This review delves into the significance of histone modifications and their influence on telomere dynamics concerning cancer. Additionally, it highlights the existing research gaps that hold the potential to drive the development of therapeutic interventions targeting the telomere epigenome.
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Affiliation(s)
- Ankita Das
- Department of Environmental Science, University of Calcutta, Kolkata 700019, India; Department of Zoology, University of Calcutta, Kolkata 700019, India
| | - Ashok K Giri
- Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Pritha Bhattacharjee
- Department of Environmental Science, University of Calcutta, Kolkata 700019, India.
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5
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Liu R, Wu J, Guo H, Yao W, Li S, Lu Y, Jia Y, Liang X, Tang J, Zhang H. Post-translational modifications of histones: Mechanisms, biological functions, and therapeutic targets. MedComm (Beijing) 2023; 4:e292. [PMID: 37220590 PMCID: PMC10200003 DOI: 10.1002/mco2.292] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 05/25/2023] Open
Abstract
Histones are DNA-binding basic proteins found in chromosomes. After the histone translation, its amino tail undergoes various modifications, such as methylation, acetylation, phosphorylation, ubiquitination, malonylation, propionylation, butyrylation, crotonylation, and lactylation, which together constitute the "histone code." The relationship between their combination and biological function can be used as an important epigenetic marker. Methylation and demethylation of the same histone residue, acetylation and deacetylation, phosphorylation and dephosphorylation, and even methylation and acetylation between different histone residues cooperate or antagonize with each other, forming a complex network. Histone-modifying enzymes, which cause numerous histone codes, have become a hot topic in the research on cancer therapeutic targets. Therefore, a thorough understanding of the role of histone post-translational modifications (PTMs) in cell life activities is very important for preventing and treating human diseases. In this review, several most thoroughly studied and newly discovered histone PTMs are introduced. Furthermore, we focus on the histone-modifying enzymes with carcinogenic potential, their abnormal modification sites in various tumors, and multiple essential molecular regulation mechanism. Finally, we summarize the missing areas of the current research and point out the direction of future research. We hope to provide a comprehensive understanding and promote further research in this field.
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Affiliation(s)
- Ruiqi Liu
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
- Graduate DepartmentBengbu Medical College, BengbuAnhuiChina
| | - Jiajun Wu
- Graduate DepartmentBengbu Medical College, BengbuAnhuiChina
- Otolaryngology & Head and Neck CenterCancer CenterDepartment of Head and Neck SurgeryZhejiang Provincial People's HospitalAffiliated People's Hospital, Hangzhou Medical CollegeHangzhouZhejiangChina
| | - Haiwei Guo
- Otolaryngology & Head and Neck CenterCancer CenterDepartment of Head and Neck SurgeryZhejiang Provincial People's HospitalAffiliated People's Hospital, Hangzhou Medical CollegeHangzhouZhejiangChina
| | - Weiping Yao
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
- Graduate DepartmentBengbu Medical College, BengbuAnhuiChina
| | - Shuang Li
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
- Graduate DepartmentJinzhou Medical UniversityJinzhouLiaoningChina
| | - Yanwei Lu
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
| | - Yongshi Jia
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
| | - Xiaodong Liang
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
- Graduate DepartmentBengbu Medical College, BengbuAnhuiChina
| | - Jianming Tang
- Department of Radiation OncologyThe First Hospital of Lanzhou UniversityLanzhou UniversityLanzhouGansuChina
| | - Haibo Zhang
- Cancer CenterDepartment of Radiation OncologyZhejiang Provincial People's HospitalAffiliated People's HospitalHangzhou Medical CollegeHangzhouZhejiangChina
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6
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Jezek M, Sun W, Negesse MY, Smith ZM, Orosz A, Green EM. Set1 regulates telomere function via H3K4 methylation-dependent and -independent pathways and calibrates the abundance of telomere maintenance factors. Mol Biol Cell 2023; 34:ar6. [PMID: 36416860 PMCID: PMC9816643 DOI: 10.1091/mbc.e22-06-0213] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/05/2022] [Accepted: 11/17/2022] [Indexed: 11/24/2022] Open
Abstract
Set1 is an H3K4 methyltransferase that comprises the catalytic subunit of the COMPASS complex and has been implicated in transcription, DNA repair, cell cycle control, and numerous other genomic functions. Set1 also promotes proper telomere maintenance, as cells lacking Set1 have short telomeres and disrupted subtelomeric gene repression; however, the precise role for Set1 in these processes has not been fully defined. In this study, we have tested mutants of Set1 and the COMPASS complex that differentially alter H3K4 methylation status, and we have attempted to separate catalytic and noncatalytic functions of Set1. Our data reveal that Set1-dependent subtelomeric gene repression relies on its catalytic activity toward H3K4, whereas telomere length is regulated by Set1 catalytic activity but likely independent of the H3K4 substrate. Furthermore, we uncover a role for Set1 in calibrating the abundance of critical telomere maintenance proteins, including components of the telomerase holoenzyme and members of the telomere capping CST (Cdc13-Stn1-Ten1) complex, through both transcriptional and posttranscriptional pathways. Altogether, our data provide new insights into the H3K4 methylation-dependent and -independent roles for Set1 in telomere maintenance in yeast and shed light on possible roles for Set1-related methyltransferases in other systems.
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Affiliation(s)
- Meagan Jezek
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250
| | - Winny Sun
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250
| | - Maraki Y. Negesse
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250
| | - Zachary M. Smith
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250
| | - Alexander Orosz
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250
| | - Erin M. Green
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201
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7
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Cai Q, Guo H, Fang R, Hua Y, Zhu Y, Zheng X, Yan J, Wang J, Hu Y, Zhang C, Zhang C, Duan R, Kong F, Zhang S, Chen D, Ji S. A Toll-dependent Bre1/Rad6-cact feedback loop in controlling host innate immune response. Cell Rep 2022; 41:111795. [PMID: 36516751 DOI: 10.1016/j.celrep.2022.111795] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 10/19/2022] [Accepted: 11/16/2022] [Indexed: 12/15/2022] Open
Abstract
The Toll signaling pathway was initially identified for its involvement in the control of early embryogenesis. It was later shown to be also part of a major innate immune pathway controlling the expression of anti-microbial peptides in many eukaryotes including humans; cactus, the essential negative regulator of this pathway in flies, was found to be induced in parallel to the Toll-dependent activation process during immune defenses. We were interested in the mechanisms of this dual effect and provide here evidence that upon pathogenic stimuli, dorsal, one of the transcription factors of the fly Toll pathway, can induce the expression of the E3 ligase Bre1. We further show that Bre1 complexes with the E2 Rad6 to mono-ubiquitinate histone H2B and to promote the transcription of cactus to achieve homeostasis of the Toll immune response. Our studies characterize a Toll signal-dependent regulatory machinery in governing the Toll pathway in Drosophila.
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Affiliation(s)
- Qingshuang Cai
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Huimin Guo
- Center for Biological Technology, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Rong Fang
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Yongzhi Hua
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Yangyang Zhu
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Xianrui Zheng
- Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou 363000, Fujian, China
| | - Jing Yan
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Jiale Wang
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Yixuan Hu
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Chuchu Zhang
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Chao Zhang
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Renjie Duan
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Fanrui Kong
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Shikun Zhang
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China
| | - Di Chen
- Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, Guangdong, China.
| | - Shanming Ji
- Center for Developmental Biology, School of Life Sciences, Anhui Agricultural University, Hefei 230036, Anhui, China.
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8
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Telomerase in Cancer: Function, Regulation, and Clinical Translation. Cancers (Basel) 2022; 14:cancers14030808. [PMID: 35159075 PMCID: PMC8834434 DOI: 10.3390/cancers14030808] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/29/2022] [Accepted: 02/02/2022] [Indexed: 02/04/2023] Open
Abstract
Simple Summary Cells undergoing malignant transformation must circumvent replicative senescence and eventual cell death associated with progressive telomere shortening that occurs through successive cell division. To do so, malignant cells reactivate telomerase to extend their telomeres and achieve cellular immortality, which is a “Hallmark of Cancer”. Here we review the telomere-dependent and -independent functions of telomerase in cancer, as well as its potential as a biomarker and therapeutic target to diagnose and treat cancer patients. Abstract During the process of malignant transformation, cells undergo a series of genetic, epigenetic, and phenotypic alterations, including the acquisition and propagation of genomic aberrations that impart survival and proliferative advantages. These changes are mediated in part by the induction of replicative immortality that is accompanied by active telomere elongation. Indeed, telomeres undergo dynamic changes to their lengths and higher-order structures throughout tumor formation and progression, processes overseen in most cancers by telomerase. Telomerase is a multimeric enzyme whose function is exquisitely regulated through diverse transcriptional, post-transcriptional, and post-translational mechanisms to facilitate telomere extension. In turn, telomerase function depends not only on its core components, but also on a suite of binding partners, transcription factors, and intra- and extracellular signaling effectors. Additionally, telomerase exhibits telomere-independent regulation of cancer cell growth by participating directly in cellular metabolism, signal transduction, and the regulation of gene expression in ways that are critical for tumorigenesis. In this review, we summarize the complex mechanisms underlying telomere maintenance, with a particular focus on both the telomeric and extratelomeric functions of telomerase. We also explore the clinical utility of telomeres and telomerase in the diagnosis, prognosis, and development of targeted therapies for primary, metastatic, and recurrent cancers.
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9
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Zipper head mechanism of telomere synthesis by human telomerase. Cell Res 2021; 31:1275-1290. [PMID: 34782750 PMCID: PMC8648750 DOI: 10.1038/s41422-021-00586-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 10/08/2021] [Indexed: 11/08/2022] Open
Abstract
Telomerase, a multi-subunit ribonucleoprotein complex, is a unique reverse transcriptase that catalyzes the processive addition of a repeat sequence to extend the telomere end using a short fragment of its own RNA component as the template. Despite recent structural characterizations of human and Tetrahymena telomerase, it is still a mystery how telomerase repeatedly uses its RNA template to synthesize telomeric DNA. Here, we report the cryo-EM structure of human telomerase holoenzyme bound with telomeric DNA at resolutions of 3.5 Å and 3.9 Å for the catalytic core and biogenesis module, respectively. The structure reveals that a leucine residue Leu980 in telomerase reverse transcriptase (TERT) catalytic subunit functions as a zipper head to limit the length of the short primer-template duplex in the active center. Moreover, our structural and computational analyses suggest that TERT and telomerase RNA (hTR) are organized to harbor a preformed active site that can accommodate short primer-template duplex substrates for catalysis. Furthermore, our findings unveil a double-fingers architecture in TERT that ensures nucleotide addition processivity of human telomerase. We propose that the zipper head Leu980 is a structural determinant for the sequence-based pausing signal of DNA synthesis that coincides with the RNA element-based physical template boundary. Functional analyses unveil that the non-glycine zipper head plays an essential role in both telomerase repeat addition processivity and telomere length homeostasis. In addition, we also demonstrate that this zipper head mechanism is conserved in all eukaryotic telomerases. Together, our study provides an integrated model for telomerase-mediated telomere synthesis.
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10
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Zhang J, Lu X, MoghaddamKohi S, Shi L, Xu X, Zhu WG. Histone lysine modifying enzymes and their critical roles in DNA double-strand break repair. DNA Repair (Amst) 2021; 107:103206. [PMID: 34411909 DOI: 10.1016/j.dnarep.2021.103206] [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] [Received: 03/29/2021] [Revised: 07/24/2021] [Accepted: 08/05/2021] [Indexed: 10/20/2022]
Abstract
Cells protect the integrity of the genome against DNA double-strand breaks through several well-characterized mechanisms including nonhomologous end-joining repair, homologous recombination repair, microhomology-mediated end-joining and single-strand annealing. However, aberrant DNA damage responses (DDRs) lead to genome instability and tumorigenesis. Clarification of the mechanisms underlying the DDR following lethal damage will facilitate the identification of therapeutic targets for cancer. Histones are small proteins that play a major role in condensing DNA into chromatin and regulating gene function. Histone modifications commonly occur in several residues including lysine, arginine, serine, threonine and tyrosine, which can be acetylated, methylated, ubiquitinated and phosphorylated. Of these, lysine modifications have been extensively explored during DDRs. Here, we focus on discussing the roles of lysine modifying enzymes involved in acetylation, methylation, and ubiquitination during the DDR. We provide a comprehensive understanding of the basis of potential epigenetic therapies driven by histone lysine modifications.
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Affiliation(s)
- Jun Zhang
- Department of Biochemistry and Molecular Biology, School of Medicine, Shenzhen University, Shenzhen, 518055, China
| | - Xiaopeng Lu
- Department of Biochemistry and Molecular Biology, School of Medicine, Shenzhen University, Shenzhen, 518055, China
| | - Sara MoghaddamKohi
- Department of Biochemistry and Molecular Biology, School of Medicine, Shenzhen University, Shenzhen, 518055, China
| | - Lei Shi
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, 300070, China.
| | - Xingzhi Xu
- Department of Cell Biology and Medical Genetics, School of Medicine, Shenzhen University, Shenzhen, 518055, China.
| | - Wei-Guo Zhu
- Department of Biochemistry and Molecular Biology, School of Medicine, Shenzhen University, Shenzhen, 518055, China.
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11
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Lu R, Zhang H, Jiang YN, Wang ZQ, Sun L, Zhou ZW. Post-Translational Modification of MRE11: Its Implication in DDR and Diseases. Genes (Basel) 2021; 12:1158. [PMID: 34440334 PMCID: PMC8392716 DOI: 10.3390/genes12081158] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 12/15/2022] Open
Abstract
Maintaining genomic stability is vital for cells as well as individual organisms. The meiotic recombination-related gene MRE11 (meiotic recombination 11) is essential for preserving genomic stability through its important roles in the resection of broken DNA ends, DNA damage response (DDR), DNA double-strand breaks (DSBs) repair, and telomere maintenance. The post-translational modifications (PTMs), such as phosphorylation, ubiquitination, and methylation, regulate directly the function of MRE11 and endow MRE11 with capabilities to respond to cellular processes in promptly, precisely, and with more diversified manners. Here in this paper, we focus primarily on the PTMs of MRE11 and their roles in DNA response and repair, maintenance of genomic stability, as well as their association with diseases such as cancer.
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Affiliation(s)
- Ruiqing Lu
- School of Medicine, Sun Yat-Sen University, Shenzhen 518107, China; (R.L.); (Y.-N.J.)
| | - Han Zhang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College; Kunming 650118, China;
| | - Yi-Nan Jiang
- School of Medicine, Sun Yat-Sen University, Shenzhen 518107, China; (R.L.); (Y.-N.J.)
| | - Zhao-Qi Wang
- Leibniz Institute on Aging–Fritz Lipmann Institute (FLI), 07745 Jena, Germany;
- Faculty of Biological Sciences, Friedrich-Schiller-University of Jena, 07745 Jena, Germany
| | - Litao Sun
- School of Public Health (Shenzhen), Sun Yat-Sen University, Shenzhen 518107, China
| | - Zhong-Wei Zhou
- School of Medicine, Sun Yat-Sen University, Shenzhen 518107, China; (R.L.); (Y.-N.J.)
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12
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Feng T, Ling S, Xu C, Ying L, Su D, Xu X. Ubiquitin-specific peptidase 22 in cancer. Cancer Lett 2021; 514:30-37. [PMID: 33989708 DOI: 10.1016/j.canlet.2021.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/21/2021] [Accepted: 05/05/2021] [Indexed: 02/07/2023]
Abstract
Recently, many studies have shown that deubiquitination modification of proteins is of great significance in major physiological processes such as cell proliferation, apoptosis, and differentiation. The ubiquitin-specific peptidase (USP) family is one of the most numerous and structurally diverse of the deubiquitinates known to date. USP22, an important member of the USP family, has been found to be closely associated with tumor cell cycle regulation, stemness maintenance, invasion and metastasis, chemoresistance, and immune regulation. We focus on recent advances regarding USP22's function in cancer and discuss the prospect of USP22 in this review.
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Affiliation(s)
- Tingting Feng
- Department of Pathology, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer(IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China; Cancer Research Institute, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer(IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China; Department of Colorectal Medicine, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer(IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China; Department of Hepatobiliary and Pancreatic Surgery, The Center for Integrated Oncology and Precision Medicine, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - Sunbin Ling
- Department of Hepatobiliary and Pancreatic Surgery, The Center for Integrated Oncology and Precision Medicine, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - Chenyang Xu
- Department of Pathology, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer(IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Lisha Ying
- Cancer Research Institute, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer(IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China
| | - Dan Su
- Department of Pathology, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer(IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China.
| | - Xiao Xu
- Department of Hepatobiliary and Pancreatic Surgery, The Center for Integrated Oncology and Precision Medicine, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China.
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13
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RPA-mediated recruitment of Bre1 couples histone H2B ubiquitination to DNA replication and repair. Proc Natl Acad Sci U S A 2021; 118:2017497118. [PMID: 33602814 DOI: 10.1073/pnas.2017497118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The ubiquitin E3 ligase Bre1-mediated H2B monoubiquitination (H2Bub) is essential for proper DNA replication and repair in eukaryotes. Deficiency in H2Bub causes genome instability and cancer. How the Bre1-H2Bub pathway is evoked in response to DNA replication or repair remains unknown. Here, we identify that the single-stranded DNA (ssDNA) binding factor RPA acts as a key mediator that couples Bre1-mediated H2Bub to DNA replication and repair in yeast. We found that RPA interacts with Bre1 in vitro and in vivo, and this interaction is stimulated by ssDNA. This association ensures the recruitment of Bre1 to replication forks or DNA breaks but does not affect its E3 ligase activity. Disruption of the interaction abolishes the local enrichment of H2Bub, resulting in impaired DNA replication, response to replication stress, and repair by homologous recombination, accompanied by increased genome instability and DNA damage sensitivity. Notably, we found that RNF20, the human homolog of Bre1, interacts with RPA70 in a conserved mode. Thus, RPA functions as a master regulator for the spatial-temporal control of H2Bub chromatin landscape during DNA replication and recombination, extending the versatile roles of RPA in guarding genome stability.
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14
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Liu JC, Li QJ, He MH, Hu C, Dai P, Meng FL, Zhou BO, Zhou JQ. Swc4 positively regulates telomere length independently of its roles in NuA4 and SWR1 complexes. Nucleic Acids Res 2021; 48:12792-12803. [PMID: 33270890 PMCID: PMC7736797 DOI: 10.1093/nar/gkaa1150] [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: 09/09/2020] [Revised: 10/19/2020] [Accepted: 11/10/2020] [Indexed: 01/25/2023] Open
Abstract
Telomeres at the ends of eukaryotic chromosomes are essential for genome integrality and stability. In order to identify genes that sustain telomere maintenance independently of telomerase recruitment, we have exploited the phenotype of over-long telomeres in the cells that express Cdc13-Est2 fusion protein, and examined 195 strains, in which individual non-essential gene deletion causes telomere shortening. We have identified 24 genes whose deletion results in dramatic failure of Cdc13-Est2 function, including those encoding components of telomerase, Yku, KEOPS and NMD complexes, as well as quite a few whose functions are not obvious in telomerase activity regulation. We have characterized Swc4, a shared subunit of histone acetyltransferase NuA4 and chromatin remodeling SWR1 (SWR1-C) complexes, in telomere length regulation. Deletion of SWC4, but not other non-essential subunits of either NuA4 or SWR1-C, causes significant telomere shortening. Consistently, simultaneous disassembly of NuA4 and SWR1-C does not affect telomere length. Interestingly, inactivation of Swc4 in telomerase null cells accelerates both telomere shortening and senescence rates. Swc4 associates with telomeric DNA in vivo, suggesting a direct role of Swc4 at telomeres. Taken together, our work reveals a distinct role of Swc4 in telomere length regulation, separable from its canonical roles in both NuA4 and SWR1-C.
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Affiliation(s)
- Jia-Cheng Liu
- The 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, Shanghai 200031, China
| | - Qian-Jin Li
- The 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, Shanghai 200031, China
| | - Ming-Hong He
- The 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, Shanghai 200031, China
| | - Can Hu
- The 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, Shanghai 200031, China
| | - Pengfei Dai
- The 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, Shanghai 200031, China
| | - Fei-Long Meng
- The 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, Shanghai 200031, China
| | - Bo O Zhou
- The 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, Shanghai 200031, China
| | - Jin-Qiu Zhou
- The 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, Shanghai 200031, China.,School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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15
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Lee JW, Ong EBB. Genomic Instability and Cellular Senescence: Lessons From the Budding Yeast. Front Cell Dev Biol 2021; 8:619126. [PMID: 33511130 PMCID: PMC7835410 DOI: 10.3389/fcell.2020.619126] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/15/2020] [Indexed: 01/14/2023] Open
Abstract
Aging is a complex biological process that occurs in all living organisms. Aging is initiated by the gradual accumulation of biomolecular damage in cells leading to the loss of cellular function and ultimately death. Cellular senescence is one such pathway that leads to aging. The accumulation of nucleic acid damage and genetic alterations that activate permanent cell-cycle arrest triggers the process of senescence. Cellular senescence can result from telomere erosion and ribosomal DNA instability. In this review, we summarize the molecular mechanisms of telomere length homeostasis and ribosomal DNA stability, and describe how these mechanisms are linked to cellular senescence and longevity through lessons learned from budding yeast.
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Affiliation(s)
- Jee Whu Lee
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia.,USM-RIKEN International Centre for Aging Science (URICAS), Universiti Sains Malaysia, Penang, Malaysia
| | - Eugene Boon Beng Ong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia.,USM-RIKEN International Centre for Aging Science (URICAS), Universiti Sains Malaysia, Penang, Malaysia
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16
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Liu J, Hong X, Liang CY, Liu JP. Simultaneous visualisation of the complete sets of telomeres from the MmeI generated terminal restriction fragments in yeasts. Yeast 2020; 37:585-595. [PMID: 32776370 DOI: 10.1002/yea.3517] [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] [Received: 05/12/2020] [Revised: 08/02/2020] [Accepted: 08/03/2020] [Indexed: 11/07/2022] Open
Abstract
Telomere length is measured using Southern blotting of the chromosomal terminal restriction fragments (TRFs) released by endonuclease digestion in cells from yeast to human. In the budding yeast Saccharomyces cerevisiae, XhoI or PstI is applied to cut the subtelomere Y' element and release TRFs from the 17 subtelomeres. However, telomeres from other 15 X-element-only subtelomeres are omitted from analysis. Here, we report a method for measuring all 32 telomeres in S. cerevisiae using the endonuclease MmeI. Based on analyses of the endonuclease cleavage sites, we found that the TRFs generated by MmeI displayed two distinguishable bands in the sizes of ~500 and ~700 bp comprising telomeres (300 bp) and subtelomeres (200-400 bp). The modified MmeI-restricted TRF (mTRF) method recapitulated telomere shortening and lengthening caused by deficiencies of YKu and Rif1 respectively in S. cerevisiae. Furthermore, we found that mTRF was also applicable to telomere length analysis in S. paradoxus strains. These results demonstrate a useful tool for simultaneous detection of telomeres from all chromosomal ends with both X-element-only and Y'-element subtelomeres in S. cerevisiae species.
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Affiliation(s)
- Jun Liu
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Xiaojing Hong
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Chao-Ya Liang
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Jun-Ping Liu
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
- Department of Immunology, Faculty of Medicine, Monash University, Prahran, Victoria, Australia
- Hudson Institute of Medical Research, Clayton, Victoria, Australia
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17
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Structural insights into telomere protection and homeostasis regulation by yeast CST complex. Nat Struct Mol Biol 2020; 27:752-762. [PMID: 32661422 DOI: 10.1038/s41594-020-0459-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 05/22/2020] [Indexed: 01/29/2023]
Abstract
Budding yeast Cdc13-Stn1-Ten1 (CST) complex plays an essential role in telomere protection and maintenance. Despite extensive studies, only structural information of individual domains of CST is available; the architecture of CST still remains unclear. Here, we report crystal structures of Kluyveromyces lactis Cdc13-telomeric-DNA, Cdc13-Stn1 and Stn1-Ten1 complexes and propose an integrated model depicting how CST assembles and plays its roles at telomeres. Surprisingly, two oligonucleotide/oligosaccharide-binding (OB) folds of Cdc13 (OB2 and OB4), previously believed to mediate Cdc13 homodimerization, actually form a stable intramolecular interaction. This OB2-OB4 module of Cdc13 is required for the Cdc13-Stn1 interaction that assembles CST into an architecture with a central ring-like core and multiple peripheral modules in a 2:2:2 stoichiometry. Functional analyses indicate that this unique CST architecture is essential for both telomere capping and homeostasis regulation. Overall, our results provide fundamentally valuable structural information regarding the CST complex and its roles in telomere biology.
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18
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Feng JX, Riddle NC. Epigenetics and genome stability. Mamm Genome 2020; 31:181-195. [PMID: 32296924 DOI: 10.1007/s00335-020-09836-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 04/07/2020] [Indexed: 12/19/2022]
Abstract
Maintaining genome stability is essential to an organism's health and survival. Breakdown of the mechanisms protecting the genome and the resulting genome instability are an important aspect of the aging process and have been linked to diseases such as cancer. Thus, a large network of interconnected pathways is responsible for ensuring genome integrity in the face of the continuous challenges that induce DNA damage. While these pathways are diverse, epigenetic mechanisms play a central role in many of them. DNA modifications, histone variants and modifications, chromatin structure, and non-coding RNAs all carry out a variety of functions to ensure that genome stability is maintained. Epigenetic mechanisms ensure the functions of centromeres and telomeres that are essential for genome stability. Epigenetic mechanisms also protect the genome from the invasion by transposable elements and contribute to various DNA repair pathways. In this review, we highlight the integral role of epigenetic mechanisms in the maintenance of genome stability and draw attention to issues in need of further study.
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Affiliation(s)
- Justina X Feng
- Department of Biology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nicole C Riddle
- Department of Biology, The University of Alabama at Birmingham, Birmingham, AL, USA.
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19
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He MH, Liu JC, Lu YS, Wu ZJ, Liu YY, Wu Z, Peng J, Zhou JQ. KEOPS complex promotes homologous recombination via DNA resection. Nucleic Acids Res 2019; 47:5684-5697. [PMID: 30937455 PMCID: PMC6582355 DOI: 10.1093/nar/gkz228] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 03/19/2019] [Accepted: 03/29/2019] [Indexed: 12/01/2022] Open
Abstract
KEOPS complex is one of the most conserved protein complexes in eukaryotes. It plays important roles in both telomere uncapping and tRNA N6-threonylcarbamoyladenosine (t6A) modification in budding yeast. But whether KEOPS complex plays any roles in DNA repair remains unknown. Here, we show that KEOPS complex plays positive roles in both DNA damage response and homologous recombination-mediated DNA repair independently of its t6A synthesis function. Additionally, KEOPS displays DNA binding activity in vitro, and is recruited to the chromatin at DNA breaks in vivo, suggesting a direct role of KEOPS in DSB repair. Mechanistically, KEOPS complex appears to promote DNA end resection through facilitating the association of Exo1 and Dna2 with DNA breaks. Interestingly, inactivation of both KEOPS and Mre11/Rad50/Xrs2 (MRX) complexes results in synergistic defect in DNA resection, revealing that KEOPS and MRX have some redundant functions in DNA resection. Thus we uncover a t6A-independent role of KEOPS complex in DNA resection, and propose that KEOPS might be a DSB sensor to assist cells in maintaining chromosome stability.
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Affiliation(s)
- Ming-Hong He
- The 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 Yueyang Road, Shanghai 200031, China
| | - Jia-Cheng Liu
- The 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 Yueyang Road, Shanghai 200031, China
| | - Yi-Si Lu
- The 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 Yueyang Road, Shanghai 200031, China
| | - Zhi-Jing Wu
- The 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 Yueyang Road, Shanghai 200031, China
| | - Ying-Ying Liu
- The 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 Yueyang Road, Shanghai 200031, China.,School of Life Science and Technology, Shanghai Tech University, 100 Haike Road, Shanghai 201201, China
| | - Zhenfang Wu
- The 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 Yueyang Road, Shanghai 200031, China
| | - Jing Peng
- The 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 Yueyang Road, Shanghai 200031, China
| | - Jin-Qiu Zhou
- The 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 Yueyang Road, Shanghai 200031, China.,School of Life Science and Technology, Shanghai Tech University, 100 Haike Road, Shanghai 201201, China
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20
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Zheng S, Li D, Lu Z, Liu G, Wang M, Xing P, Wang M, Dong Y, Wang X, Li J, Zhang S, Peng H, Ira G, Li G, Chen X. Bre1-dependent H2B ubiquitination promotes homologous recombination by stimulating histone eviction at DNA breaks. Nucleic Acids Res 2019; 46:11326-11339. [PMID: 30304473 PMCID: PMC6265479 DOI: 10.1093/nar/gky918] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 10/08/2018] [Indexed: 01/21/2023] Open
Abstract
Repair of DNA double-strand breaks (DSBs) requires eviction of the histones around DNA breaks to allow the loading of numerous repair and checkpoint proteins. However, the mechanism and regulation of this process remain poorly understood. Here, we show that histone H2B ubiquitination (uH2B) promotes histone eviction at DSBs independent of resection or ATP-dependent chromatin remodelers. Cells lacking uH2B or its E3 ubiquitin ligase Bre1 exhibit hyper-resection due to the loss of H3K79 methylation that recruits Rad9, a known negative regulator of resection. Unexpectedly, despite excessive single-strand DNA being produced, bre1Δ cells show defective RPA and Rad51 recruitment and impaired repair by homologous recombination and response to DNA damage. The HR defect in bre1Δ cells correlates with impaired histone loss at DSBs and can be largely rescued by depletion of CAF-1, a histone chaperone depositing histones H3-H4. Overexpression of Rad51 stimulates histone eviction and partially suppresses the recombination defects of bre1Δ mutant. Thus, we propose that Bre1 mediated-uH2B promotes DSB repair through facilitating histone eviction and subsequent loading of repair proteins.
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Affiliation(s)
- Sihao Zheng
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Dan Li
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Zhen Lu
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Guangxue Liu
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Meng Wang
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Poyuan Xing
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Min Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yang Dong
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Xuejie Wang
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Jingyao Li
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Simin Zhang
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Haoyang Peng
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
| | - Grzegorz Ira
- The Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Guohong Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuefeng Chen
- Hubei Key Laboratory of Cell Homeostasis, the Department of Genetics, College of Life Sciences and the Institute for Advanced Studies, Wuhan University, Wuhan, Hubei 430072, China
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21
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Jezek M, Green EM. Histone Modifications and the Maintenance of Telomere Integrity. Cells 2019; 8:E199. [PMID: 30823596 PMCID: PMC6407025 DOI: 10.3390/cells8020199] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 02/09/2019] [Accepted: 02/20/2019] [Indexed: 12/20/2022] Open
Abstract
Telomeres, the nucleoprotein structures at the ends of eukaryotic chromosomes, play an integral role in protecting linear DNA from degradation. Dysregulation of telomeres can result in genomic instability and has been implicated in increased rates of cellular senescence and many diseases, including cancer. The integrity of telomeres is maintained by a coordinated network of proteins and RNAs, such as the telomerase holoenzyme and protective proteins that prevent the recognition of the telomere ends as a DNA double-strand breaks. The structure of chromatin at telomeres and within adjacent subtelomeres has been implicated in telomere maintenance pathways in model systems and humans. Specific post-translational modifications of histones, including methylation, acetylation, and ubiquitination, have been shown to be necessary for maintaining a chromatin environment that promotes telomere integrity. Here we review the current knowledge regarding the role of histone modifications in maintaining telomeric and subtelomeric chromatin, discuss the implications of histone modification marks as they relate to human disease, and highlight key areas for future research.
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Affiliation(s)
- Meagan Jezek
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
| | - Erin M Green
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
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22
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Hsu SH, Chen SH, Kuo CC, Chang JY. Ubiquitin-conjugating enzyme E2 B regulates the ubiquitination of O 6-methylguanine-DNA methyltransferase and BCNU sensitivity in human nasopharyngeal carcinoma cells. Biochem Pharmacol 2018; 158:327-338. [PMID: 30449727 DOI: 10.1016/j.bcp.2018.10.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/25/2018] [Indexed: 02/06/2023]
Abstract
O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes the alkyl groups from the O6 position of guanine and is then degraded via ubiquitin-mediated degradation. Previous studies indicated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) facilitates the ubiquitination and degradation of MGMT in several types of cancer cells. However, the underlying mechanism of MGMT ubiquitination remains unclear. In this study, we demonstrated for the first time that ubiquitin-conjugating enzyme E2 B (UBE2B) is a novel regulator of MGMT ubiquitination mediated by BCNU in nasopharyngeal carcinoma (NPC) cells. The E3 ubiquitin ligase RAD18, a partner of UBE2B, is also involved in BCNU-mediated MGMT ubiquitination. Overexpression/knockdown of UBE2B enhanced/reduced BCNU-mediated MGMT ubiquitination. Surprisingly, UBE2B knockdown significantly increased BCNU cytotoxicity in NPC cells. Therefore, loss of UBE2B seems to disrupt ubiquitin-mediated degradation of alkylated MGMT. We found that UBE2B knockdown reduced MGMT activity, suggesting that loss of UBE2B leads to the accumulation of deactivated MGMT and suppresses MGMT protein turnover in BCNU-treated cells. These findings indicate that UBE2B modulates sensitivity to BCNU in NPC cells by regulating MGMT ubiquitination.
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Affiliation(s)
- Shih-Han Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan
| | - Shang-Hung Chen
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Chuan Kuo
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan
| | - Jang-Yang Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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23
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Zhang LL, Wu Z, Zhou JQ. Tel1 and Rif2 oppositely regulate telomere protection at uncapped telomeres in Saccharomyces cerevisiae. J Genet Genomics 2018; 45:467-476. [PMID: 30279093 DOI: 10.1016/j.jgg.2018.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 09/06/2018] [Accepted: 09/10/2018] [Indexed: 12/27/2022]
Abstract
It has been well documented that Tel1 positively regulates telomere-end resection by promoting Mre11-Rad50-Xrs2 (MRX) activity, while Rif2 negatively regulates telomere-end resection by inhibiting MRX activity. At uncapped telomeres, whether Tel1 or Rif2 plays any role remains largely unknown. In this work, we examined the roles of Tel1 and Rif2 at uncapped telomeres in yku70Δ and/or cdc13-1 mutant cells cultured at non-permissive temperature. We found that deletion of TEL1 exacerbates the temperature sensitivity of both yku70Δ and cdc13-1 cells. Further epistasis analysis indicated that MRX and Tel1 function in the same pathway in telomere protection. Consistently, TEL1 deletion increases accumulation of Exo1-dependent telomeric single-stranded DNA (ssDNA) at uncapped telomeres, which stimulates checkpoint-dependent cell cycle arrest. Moreover, TEL1 deletion in yku70Δ cells facilitates Rad51-dependent Y' recombination. In contrast, RIF2 deletion in yku70Δ cells decreases the accumulation of telomeric ssDNA after 8 h of incubation at the non-permissive temperature of 37 °C and suppresses the temperature sensitivity of yku70Δ cells, likely due to the increase of Mre11 association at telomeres. Collectively, our findings indicate that Tel1 and Rif2 regulate telomere protection at uncapped telomeres via their roles in balancing MRX activity in telomere resection.
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Affiliation(s)
- Ling-Li Zhang
- 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, Shanghai 200031, China
| | - Zhenfang Wu
- 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, Shanghai 200031, China.
| | - Jin-Qiu Zhou
- 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, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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24
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Rad6-Bre1 mediated histone H2Bub1 protects uncapped telomeres from exonuclease Exo1 in Saccharomyces cerevisiae. DNA Repair (Amst) 2018; 72:64-76. [PMID: 30254011 DOI: 10.1016/j.dnarep.2018.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/22/2018] [Accepted: 09/14/2018] [Indexed: 12/11/2022]
Abstract
Histone H2B lysine 123 mono-ubiquitination (H2Bub1), catalyzed by Rad6 and Bre1 in Saccharomyces cerevisiae, modulates chromatin structure and affects diverse cellular functions. H2Bub1 plays roles in telomeric silencing and telomere replication. Here, we have explored a novel role of H2Bub1 in telomere protection at uncapped telomeres in yku70Δ and cdc13-1 cells. Deletion of RAD6 or BRE1, or mutation of H2BK123R enhances the temperature sensitivity of both yku70Δ and cdc13-1 telomere capping mutants. Consistently, BRE1 deletion increases accumulation of telomeric single-stranded DNA (ssDNA) in yku70Δ and cdc13-1 cells, and EXO1 deletion improves the growth of yku70Δ bre1Δ and cdc13-1 bre1Δ cells and decreases ssDNA accumulation. Additionally, deletion of BRE1 exacerbates the rate of entry into senescence of yku70Δ mre11Δ cells with telomere defects, and increases the recombination of subtelomeric Y' element that is required for telomere maintenance and survivor generation. Furthermore, Exo1 contributes to the abrupt senescence of yku70Δ mre11Δ bre1Δ cells, and Rad51 is essential for Y' recombination to generate survivors. Finally, deletion of BRE1 or mutation of H2BK123R results in nucleosome instability at subtelomeric regions. Collectively, this study provides a mechanistic link between H2Bub1-mediated chromatin structure and telomere protection after telomere uncapping.
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25
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Shao Y, Lu N, Wu Z, Cai C, Wang S, Zhang LL, Zhou F, Xiao S, Liu L, Zeng X, Zheng H, Yang C, Zhao Z, Zhao G, Zhou JQ, Xue X, Qin Z. Creating a functional single-chromosome yeast. Nature 2018; 560:331-335. [PMID: 30069045 DOI: 10.1038/s41586-018-0382-x] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 06/22/2018] [Indexed: 02/02/2023]
Abstract
Eukaryotic genomes are generally organized in multiple chromosomes. Here we have created a functional single-chromosome yeast from a Saccharomyces cerevisiae haploid cell containing sixteen linear chromosomes, by successive end-to-end chromosome fusions and centromere deletions. The fusion of sixteen native linear chromosomes into a single chromosome results in marked changes to the global three-dimensional structure of the chromosome due to the loss of all centromere-associated inter-chromosomal interactions, most telomere-associated inter-chromosomal interactions and 67.4% of intra-chromosomal interactions. However, the single-chromosome and wild-type yeast cells have nearly identical transcriptome and similar phenome profiles. The giant single chromosome can support cell life, although this strain shows reduced growth across environments, competitiveness, gamete production and viability. This synthetic biology study demonstrates an approach to exploration of eukaryote evolution with respect to chromosome structure and function.
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Affiliation(s)
- Yangyang Shao
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ning Lu
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhenfang Wu
- The 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, Shanghai, China
| | - Chen Cai
- University of Chinese Academy of Sciences, Beijing, China.,The 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, Shanghai, China
| | - Shanshan Wang
- The 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, Shanghai, China
| | - Ling-Li Zhang
- University of Chinese Academy of Sciences, Beijing, China.,The 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, Shanghai, China
| | - Fan Zhou
- Frasergen Bioinformatics Co., Ltd, Wuhan, China
| | - Shijun Xiao
- Frasergen Bioinformatics Co., Ltd, Wuhan, China
| | - Lin Liu
- Frasergen Bioinformatics Co., Ltd, Wuhan, China
| | | | - Huajun Zheng
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Chen Yang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Zhihu Zhao
- Beijing Institute of Biotechnology, Beijing, China
| | - Guoping Zhao
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China. .,Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China. .,Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China. .,State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences and Institute of Biomedical Sciences, Fudan University, Shanghai, China.
| | - Jin-Qiu Zhou
- The 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, Shanghai, China.
| | - Xiaoli Xue
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
| | - Zhongjun Qin
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
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26
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Syed A, Tainer JA. The MRE11-RAD50-NBS1 Complex Conducts the Orchestration of Damage Signaling and Outcomes to Stress in DNA Replication and Repair. Annu Rev Biochem 2018; 87:263-294. [PMID: 29709199 PMCID: PMC6076887 DOI: 10.1146/annurev-biochem-062917-012415] [Citation(s) in RCA: 255] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Genomic instability in disease and its fidelity in health depend on the DNA damage response (DDR), regulated in part from the complex of meiotic recombination 11 homolog 1 (MRE11), ATP-binding cassette-ATPase (RAD50), and phosphopeptide-binding Nijmegen breakage syndrome protein 1 (NBS1). The MRE11-RAD50-NBS1 (MRN) complex forms a multifunctional DDR machine. Within its network assemblies, MRN is the core conductor for the initial and sustained responses to DNA double-strand breaks, stalled replication forks, dysfunctional telomeres, and viral DNA infection. MRN can interfere with cancer therapy and is an attractive target for precision medicine. Its conformations change the paradigm whereby kinases initiate damage sensing. Delineated results reveal kinase activation, posttranslational targeting, functional scaffolding, conformations storing binding energy and enabling access, interactions with hub proteins such as replication protein A (RPA), and distinct networks at DNA breaks and forks. MRN biochemistry provides prototypic insights into how it initiates, implements, and regulates multifunctional responses to genomic stress.
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Affiliation(s)
- Aleem Syed
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
| | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA; ,
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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27
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Yeast KEOPS complex regulates telomere length independently of its t 6A modification function. J Genet Genomics 2018; 45:247-257. [PMID: 29804714 DOI: 10.1016/j.jgg.2018.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/15/2018] [Accepted: 03/23/2018] [Indexed: 11/24/2022]
Abstract
In Saccharomyces cerevisiae, the highly conserved Sua5 and KEOPS complex (including five subunits Kae1, Bud32, Cgi121, Pcc1 and Gon7) catalyze a universal tRNA modification, namely N6-threonylcarbamoyladenosine (t6A), and regulate telomere replication and recombination. However, whether telomere regulation function of Sua5 and KEOPS complex depends on the t6A modification activity remains unclear. Here we show that Sua5 and KEOPS regulate telomere length in the same genetic pathway. Interestingly, the telomere length regulation by KEOPS is independent of its t6A biosynthesis activity. Cytoplasmic overexpression of Qri7, a functional counterpart of KEOPS in mitochondria, restores cytosolic tRNA t6A modification and cell growth, but is not sufficient to rescue telomere length in the KEOPS mutant kae1Δ cells, indicating that a t6A modification-independent function is responsible for the telomere regulation. The results of our in vitro biochemical and in vivo genetic assays suggest that telomerase RNA TLC1 might not be modified by Sua5 and KEOPS. Moreover, deletion of KEOPS subunits results in a dramatic reduction of telomeric G-overhang, suggesting that KEOPS regulates telomere length by promoting G-overhang generation. These findings support a model in which KEOPS regulates telomere replication independently of its function on tRNA modification.
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28
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The evolutionarily conserved factor Sus1/ENY2 plays a role in telomere length maintenance. Curr Genet 2017; 64:635-644. [DOI: 10.1007/s00294-017-0778-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 11/02/2017] [Accepted: 11/03/2017] [Indexed: 11/26/2022]
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