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Tian J, Jiang L, Li H, Dan J, Luo Y. The dual role of the DREAM/G2M pathway in non-tumorigenic immortalization of senescent cells. FEBS Open Bio 2024; 14:331-343. [PMID: 38073074 PMCID: PMC10839291 DOI: 10.1002/2211-5463.13748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/04/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023] Open
Abstract
Anti-aging and tumorigenesis share common genes and pathways, and thus targeting these genes as part of anti-aging interventions carries the risk of tumorigenesis. It is essential to understand the gene signatures that balance tumorigenesis and aging. To achieve this goal, we analyzed RNA-sequencing data from three non-tumorigenic immortalized cell lines that spontaneously escaped from senescence. By single sample gene set enrichment assay (ssGSEA) and GSEA analysis, we found that both cell growth signaling (E2F targets, MYC targets) and tumor surveillance mechanisms (DNA repair, G2M checkpoint, mitotic spindle) were up-regulated in all three cell lines, suggesting that these genes are potential signatures for non-tumorigenic immortalization. Further analysis revealed that the 182 commonly up-regulated genes in these three cell lines overlapped with the DREAM/G2M pathway, which is known to be the upstream regulator of E2F, Myc targets, DNA repair, G2M checkpoint and mitotic spindle pathways in its cell cycle activation or inhibitory form. By western blotting, quantitative PCR and co-immunoprecipitation, we verified that both forms of the DREAM pathway are up-regulated in all three cell lines; this pathway facilitates control of cell cycle progression, supporting a new mechanism for non-tumorigenic immortalization. Thus, we propose that the DREAM/G2M pathway plays important dual roles with respect to preventing tumorigenesis in the process of immortalization. Our data might serve as the basis for the identification of new signature pathways or gene biomarkers for non-tumorigenic immortalization, and may aid in the discovery of new targets for tumor-free anti-aging drug screening.
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Affiliation(s)
- Jie Tian
- Department of Pathophysiology, School of Basic MedicineGuizhou Medical UniversityGuiyangChina
| | - Liangxia Jiang
- Department of Pathophysiology, School of Basic MedicineGuizhou Medical UniversityGuiyangChina
| | - Haili Li
- School of Basic MedicineShandong First Medical University & Shandong Academy of Medical SciencesJinanChina
| | - Juhua Dan
- Laboratory of Molecular Genetics of Aging & Tumor, Medical SchoolKunming University of Science and TechnologyChina
| | - Ying Luo
- Department of Pathophysiology, School of Basic MedicineGuizhou Medical UniversityGuiyangChina
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2
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Ito M, Fujita Y, Shinohara A. Positive and negative regulators of RAD51/DMC1 in homologous recombination and DNA replication. DNA Repair (Amst) 2024; 134:103613. [PMID: 38142595 DOI: 10.1016/j.dnarep.2023.103613] [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: 08/02/2023] [Revised: 12/10/2023] [Accepted: 12/10/2023] [Indexed: 12/26/2023]
Abstract
RAD51 recombinase plays a central role in homologous recombination (HR) by forming a nucleoprotein filament on single-stranded DNA (ssDNA) to catalyze homology search and strand exchange between the ssDNA and a homologous double-stranded DNA (dsDNA). The catalytic activity of RAD51 assembled on ssDNA is critical for the DNA-homology-mediated repair of DNA double-strand breaks in somatic and meiotic cells and restarting stalled replication forks during DNA replication. The RAD51-ssDNA complex also plays a structural role in protecting the regressed/reversed replication fork. Two types of regulators control RAD51 filament formation, stability, and dynamics, namely positive regulators, including mediators, and negative regulators, so-called remodelers. The appropriate balance of action by the two regulators assures genome stability. This review describes the roles of positive and negative RAD51 regulators in HR and DNA replication and its meiosis-specific homolog DMC1 in meiotic recombination. We also provide future study directions for a comprehensive understanding of RAD51/DMC1-mediated regulation in maintaining and inheriting genome integrity.
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Affiliation(s)
- Masaru Ito
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
| | - Yurika Fujita
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
| | - Akira Shinohara
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
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3
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Loe TK, Lazzerini Denchi E, Tricola GM, Azeroglu B. ALTercations at telomeres: stress, recombination and extrachromosomal affairs. Biochem Soc Trans 2023; 51:1935-1946. [PMID: 37767563 DOI: 10.1042/bst20230265] [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: 08/11/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 09/29/2023]
Abstract
Approximately 15% of human cancers depend on the alternative lengthening of telomeres (ALT) pathway to maintain telomeres and proliferate. Telomeres that are elongated using ALT display unique features raising the exciting prospect of tailored cancer therapies. ALT-mediated telomere elongation shares several features with recombination-based DNA repair. Strikingly, cells that use the ALT pathway display abnormal levels of replication stress at telomeres and accumulate abundant extrachromosomal telomeric DNA. In this review, we examine recent findings that shed light on the ALT mechanisms and the strategies currently available to suppress this telomere elongation mechanism.
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Affiliation(s)
- Taylor K Loe
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, U.S.A
| | - Eros Lazzerini Denchi
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, U.S.A
| | - Gianna M Tricola
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, U.S.A
| | - Benura Azeroglu
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, U.S.A
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4
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Wang Q, Hou K, Yang J, Li H, Li C, Zhang Y, Tian J, Li C, Guo B, Jia S, Luo Y. Modified iPOND revealed the role of mutant p53 in promoting helicase function and telomere maintenance. Aging (Albany NY) 2023; 15:10767-10784. [PMID: 37827695 PMCID: PMC10599736 DOI: 10.18632/aging.205117] [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: 02/11/2023] [Accepted: 09/25/2023] [Indexed: 10/14/2023]
Abstract
The G-rich DNA, such as telomere, tends to form G-quadruplex (G4) structure, which slows down the replication fork progression, induces replication stress, and becomes the chromosome fragile sites. Here we described a molecular strategy that cells developed to overcome the DNA replication stress via DNA helicase regulation. The p53N236S (p53S) mutation has been found in the Werner syndrome mouse embryo fibroblast (MEFs) escaped from senescence, could be the driving force for cell escaping senescence. We revealed that the p53S could transcriptionally up-regulate DNA helicases expression, including Wrn, Blm, Timeless, Ddx, Mcm, Gins, Fanc, as well as telomere specific proteins Terf1, Pot1, through which p53S promoted the unwinding of G4 structures, and protected the cells from DNA replication stress induced by G4 stabilizer. By modified iPOND (isolation of proteins on nascent DNA) assay and telomere assay, we demonstrated that the p53S could promote the recruitment of those helicases to the DNA replication forks, facilitated the maintenance of telomere, and prevent the telomere dysfunction induced by G4 stabilizer. Interestingly, we did not observe the function of promoting G4 resolving and facilitating telomere lengthening in the cells with Li-Fraumeni Syndrome mutation-p53R172H (p53H), which suggests that this is the specific gain of function for p53S. Together our data suggest that the p53S could gain the new function of releasing the replication stress via regulating the helicase function and G4 structure, which benefits telomere lengthening. This strategy could be applied to the treatment of diseases caused by telomere replication stress.
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Affiliation(s)
- Qianqian Wang
- Department of Pathophysiology, School of Basic Medicine, Guizhou Medical University, Guiyang 550025, Guizhou, China
| | - Kailong Hou
- Lab of Molecular Genetics of Aging and Tumor, Medical School, Kunming University of Science and Technology, Kunming 650500, Yunnan Province, China
| | - Jun Yang
- Department of Pathophysiology, School of Basic Medicine, Guizhou Medical University, Guiyang 550025, Guizhou, China
| | - Haili Li
- Department of Human Anatomy, School of Basic Medicine, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, Shandong, China
| | - Cui Li
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, Guangdong, China
| | - Yanduo Zhang
- Lab of Molecular Genetics of Aging and Tumor, Medical School, Kunming University of Science and Technology, Kunming 650500, Yunnan Province, China
| | - Jie Tian
- Department of Pathophysiology, School of Basic Medicine, Guizhou Medical University, Guiyang 550025, Guizhou, China
| | - Chuanbiao Li
- Department of Pathophysiology, School of Basic Medicine, Guizhou Medical University, Guiyang 550025, Guizhou, China
| | - Bing Guo
- Department of Pathophysiology, School of Basic Medicine, Guizhou Medical University, Guiyang 550025, Guizhou, China
| | - Shuting Jia
- Lab of Molecular Genetics of Aging and Tumor, Medical School, Kunming University of Science and Technology, Kunming 650500, Yunnan Province, China
| | - Ying Luo
- Department of Pathophysiology, School of Basic Medicine, Guizhou Medical University, Guiyang 550025, Guizhou, China
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5
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Sohn EJ, Goralsky JA, Shay JW, Min J. The Molecular Mechanisms and Therapeutic Prospects of Alternative Lengthening of Telomeres (ALT). Cancers (Basel) 2023; 15:cancers15071945. [PMID: 37046606 PMCID: PMC10093677 DOI: 10.3390/cancers15071945] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 04/14/2023] Open
Abstract
As detailed by the end replication problem, the linear ends of a cell's chromosomes, known as telomeres, shorten with each successive round of replication until a cell enters into a state of growth arrest referred to as senescence. To maintain their immortal proliferation capacity, cancer cells must employ a telomere maintenance mechanism, such as telomerase activation or the Alternative Lengthening of Telomeres pathway (ALT). With only 10-15% of cancers utilizing the ALT mechanism, progress towards understanding its molecular components and associated hallmarks has only recently been made. This review analyzes the advances towards understanding the ALT pathway by: (1) detailing the mechanisms associated with engaging the ALT pathway as well as (2) identifying potential therapeutic targets of ALT that may lead to novel cancer therapeutic treatments. Collectively, these studies indicate that the ALT molecular mechanisms involve at least two distinct pathways induced by replication stress and damage at telomeres. We suggest exploiting tumor dependency on ALT is a promising field of study because it suggests new approaches to ALT-specific therapies for cancers with poorer prognosis. While substantial progress has been made in the ALT research field, additional progress will be required to realize these advances into clinical practices to treat ALT cancers and improve patient prognoses.
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Affiliation(s)
- Eric J Sohn
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Julia A Goralsky
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Jaewon Min
- Institute for Cancer Genetics, Columbia University Irving Medical Center, New York, NY 10032, USA
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA
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6
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Datta A, Brosh RM. WRN rescues replication forks compromised by a BRCA2 deficiency: Predictions for how inhibition of a helicase that suppresses premature aging tilts the balance to fork demise and chromosomal instability in cancer. Bioessays 2022; 44:e2200057. [PMID: 35751457 PMCID: PMC9527950 DOI: 10.1002/bies.202200057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 06/03/2022] [Accepted: 06/08/2022] [Indexed: 11/08/2022]
Abstract
Hereditary breast and ovarian cancers are frequently attributed to germline mutations in the tumor suppressor genes BRCA1 and BRCA2. BRCA1/2 act to repair double-strand breaks (DSBs) and suppress the demise of unstable replication forks. Our work elucidated a dynamic interplay between BRCA2 and the WRN DNA helicase/exonuclease defective in the premature aging disorder Werner syndrome. WRN and BRCA2 participate in complementary pathways to stabilize replication forks in cancer cells, allowing them to proliferate. Whether the functional overlap of WRN and BRCA2 is relevant to replication at gaps between newly synthesized DNA fragments, protection of telomeres, and/or metabolism of secondary DNA structures remain to be determined. Advances in understanding the mechanisms elicited during replication stress have prompted the community to reconsider avenues for cancer therapy. Insights from studies of PARP or topoisomerase inhibitors provide working models for the investigation of WRN's mechanism of action. We discuss these topics, focusing on the implications of the WRN-BRCA2 genetic interaction under conditions of replication stress.
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Affiliation(s)
- Arindam Datta
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, Maryland, USA
| | - Robert M Brosh
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, Maryland, USA
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7
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Gudmundsrud R, Skjånes TH, Gilmour BC, Caponio D, Lautrup S, Fang EF. Crosstalk among DNA Damage, Mitochondrial Dysfunction, Impaired Mitophagy, Stem Cell Attrition, and Senescence in the Accelerated Ageing Disorder Werner Syndrome. Cytogenet Genome Res 2021; 161:297-304. [PMID: 34433164 DOI: 10.1159/000516386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/10/2020] [Indexed: 12/13/2022] Open
Abstract
Werner syndrome (WS) is an accelerated ageing disease caused by multiple mutations in the gene encoding the Werner DNA helicase (WRN). The major clinical features of WS include wrinkles, grey hair, osteoporosis, and metabolic phenomena such as atherosclerosis, diabetes, and fatty liver, and resemble those seen in normal ageing, but occur earlier, in middle age. Defective DNA repair resulting from mutations in WRN explain the majority of the clinical features of WS, but the underlying mechanisms driving the larger metabolic dysfunction remain elusive. Recent studies in animal models of WS and in WS patient cells and blood samples suggest the involvement of impaired mitophagy, NAD+ depletion, and accumulation of damaged mitochondria in metabolic dysfunction. This mini-review summarizes recent progress in the understanding of the molecular mechanisms of metabolic dysfunction in WS, with the involvement of DNA damage, mitochondrial dysfunction, mitophagy reduction, stem cell impairment, and senescence. Future studies on NAD+ and mitophagy may shed light on potential therapeutic strategies for the WS patients.
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Affiliation(s)
- Ruben Gudmundsrud
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Tarjei H Skjånes
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Brian C Gilmour
- The Norwegian Centre on Healthy Ageing (NO-Age), Oslo, Norway
| | - Domenica Caponio
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Sofie Lautrup
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Evandro F Fang
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway.,The Norwegian Centre on Healthy Ageing (NO-Age), Oslo, Norway
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8
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Lee JH, Hong J, Zhang Z, de la Peña Avalos B, Proietti CJ, Deamicis AR, Guzmán G P, Lam HM, Garcia J, Roudier MP, Sisk AE, De La Rosa R, Vu K, Yang M, Liao Y, Scheirer J, Pechacek D, Yadav P, Rao MK, Zheng S, Johnson-Pais TL, Leach RJ, Elizalde PV, Dray E, Xu K. Regulation of telomere homeostasis and genomic stability in cancer by N 6-adenosine methylation (m 6A). SCIENCE ADVANCES 2021; 7:7/31/eabg7073. [PMID: 34321211 PMCID: PMC8318370 DOI: 10.1126/sciadv.abg7073] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 06/11/2021] [Indexed: 05/04/2023]
Abstract
The role of RNA methylation on N 6-adenosine (m6A) in cancer has been acknowledged, but the underlying mechanisms remain obscure. Here, we identified homeobox containing 1 (HMBOX1) as an authentic target mRNA of m6A machinery, which is highly methylated in malignant cells compared to the normal counterparts and subject to expedited degradation upon the modification. m6A-mediated down-regulation of HMBOX1 causes telomere dysfunction and inactivation of p53 signaling, which leads to chromosome abnormalities and aggressive phenotypes. CRISPR-based, m6A-editing tools further prove that the methyl groups on HMBOX1 per se contribute to the generation of altered cancer genome. In multiple types of human cancers, expression of the RNA methyltransferase METTL3 is negatively correlated with the telomere length but favorably with fractions of altered cancer genome, whereas HMBOX1 mRNA levels show the opposite patterns. Our work suggests that the cancer-driving genomic alterations may potentially be fixed by rectifying particular epitranscriptomic program.
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Affiliation(s)
- Ji Hoon Lee
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Juyeong Hong
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Zhao Zhang
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Bárbara de la Peña Avalos
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX 78229, USA
- Mays Cancer Center, UT Health San Antonio MD Anderson, San Antonio, TX 78229, USA
| | - Cecilia J Proietti
- Laboratory of Molecular Mechanisms of Carcinogenesis and Molecular Endocrinology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires C1428ADN, Argentina
| | - Agustina Roldán Deamicis
- Laboratory of Molecular Mechanisms of Carcinogenesis and Molecular Endocrinology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires C1428ADN, Argentina
| | - Pablo Guzmán G
- Departamento de Anatomía Patológica (BIOREN), Universidad de La Frontera, Temuco Casilla 54-D, Chile
| | - Hung-Ming Lam
- Department of Urology, University of Washington, Seattle, WA 98195, USA
| | - Jose Garcia
- Department of Urology, University of Washington, Seattle, WA 98195, USA
| | - Martine P Roudier
- Department of Urology, University of Washington, Seattle, WA 98195, USA
| | - Anthony E Sisk
- Department of Pathology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Richard De La Rosa
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Kevin Vu
- Department of Medical Education, Joe R. and Teresa Lozano Long School of Medicine, San Antonio, TX 78229, USA
| | - Mei Yang
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Yiji Liao
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Jessica Scheirer
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Douglas Pechacek
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Pooja Yadav
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Manjeet K Rao
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Siyuan Zheng
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Department of Population Health Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Teresa L Johnson-Pais
- Department of Urology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX 78229, USA
| | - Robin J Leach
- Mays Cancer Center, UT Health San Antonio MD Anderson, San Antonio, TX 78229, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Patricia V Elizalde
- Laboratory of Molecular Mechanisms of Carcinogenesis and Molecular Endocrinology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires C1428ADN, Argentina
| | - Eloïse Dray
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX 78229, USA
- Mays Cancer Center, UT Health San Antonio MD Anderson, San Antonio, TX 78229, USA
| | - Kexin Xu
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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9
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Wang T, Zhang H, Zhou Y, Shi J. Extrachromosomal circular DNA: a new potential role in cancer progression. J Transl Med 2021; 19:257. [PMID: 34112178 PMCID: PMC8194206 DOI: 10.1186/s12967-021-02927-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/04/2021] [Indexed: 12/15/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) is considered a circular DNA molecule that exists widely in nature and is independent of conventional chromosomes. eccDNA can be divided into small polydispersed circular DNA (spcDNA), telomeric circles (t-circles), microDNA, and extrachromosomal DNA (ecDNA) according to its size and sequence. Multiple studies have shown that eccDNA is the product of genomic instability, has rich and important biological functions, and is involved in the occurrence of many diseases, including cancer. In this review, we focus on the discovery history, formation process, characteristics, and physiological functions of eccDNAs; the potential functions of various eccDNAs in human cancer; and the research methods employed to study eccDNA.
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Affiliation(s)
- Tianyi Wang
- Nantong Key Laboratory of Translational Medicine in Cardiothoracic Diseases, and Research Institution of Translational Medicine in Cardiothoracic Diseases, Affiliated Hospital of Nantong University, No. 20, Xisi Road, Nantong, 226001, Jiangsu, China.,Department of Thoracic Surgery, Affiliated Hospital of Nantong University, No. 20, Xisi Road, Nantong, 226001, Jiangsu, China
| | - Haijian Zhang
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, No. 20, Xisi Road, Nantong, 226001, Jiangsu, China
| | - Youlang Zhou
- Research Center of Clinical Medicine, Affiliated Hospital of Nantong University, No. 20, Xisi Road, Nantong, 226001, Jiangsu, China
| | - Jiahai Shi
- Nantong Key Laboratory of Translational Medicine in Cardiothoracic Diseases, and Research Institution of Translational Medicine in Cardiothoracic Diseases, Affiliated Hospital of Nantong University, No. 20, Xisi Road, Nantong, 226001, Jiangsu, China. .,Department of Thoracic Surgery, Affiliated Hospital of Nantong University, No. 20, Xisi Road, Nantong, 226001, Jiangsu, China.
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10
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Ngoi NY, Liew AQ, Chong SJF, Davids MS, Clement MV, Pervaiz S. The redox-senescence axis and its therapeutic targeting. Redox Biol 2021; 45:102032. [PMID: 34147844 PMCID: PMC8220395 DOI: 10.1016/j.redox.2021.102032] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 12/14/2022] Open
Abstract
Significance Cellular growth arrest, associated with ‘senescence’, helps to safeguard against the accumulation of DNA damage which is often recognized as the underlying mechanism of a wide variety of age-related pathologies including cancer. Cellular senescence has also been described as a ‘double-edged sword’. In cancer, for example, the creation of an immune-suppressive milieu by senescent tumor cells through the senescence-associated secretory phenotype contributes toward carcinogenesis and cancer progression. Recent advances The potential for cellular senescence to confer multi-faceted effects on tissue fate has led to a rejuvenated interest in its landscape and targeting. Interestingly, redox pathways have been described as both triggers and propagators of cellular senescence, leading to intricate cross-links between both pathways. Critical issues In this review, we describe the mechanisms driving cellular senescence, the interface with cellular redox metabolism as well as the role that chemotherapy-induced senescence plays in secondary carcinogenesis. Notably, the role that anti-apoptotic proteins of the Bcl-2 family play in inducing drug resistance via mechanisms that involve senescence induction. Future directions Though the therapeutic targeting of senescent cells as cancer therapy remains in its infancy, we summarize the current development of senotherapeutics, including recognized senotherapies, as well as the repurposing of drugs as senomorphic/senolytic candidates.
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Affiliation(s)
- Natalie Yl Ngoi
- Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore
| | - Angeline Qx Liew
- Integrative Science and Engineering Programme (ISEP), NUS Graduate School (NUSGS), National University of Singapore, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Stephen J F Chong
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Matthew S Davids
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Marie-Veronique Clement
- Integrative Science and Engineering Programme (ISEP), NUS Graduate School (NUSGS), National University of Singapore, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; NUS Medicine Healthy Longevity Program, National University of Singapore, Singapore
| | - Shazib Pervaiz
- Integrative Science and Engineering Programme (ISEP), NUS Graduate School (NUSGS), National University of Singapore, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; NUS Medicine Healthy Longevity Program, National University of Singapore, Singapore; NUS Centre for Cancer Research (N2CR), Yong Loo Lin School of Medicine, National University of Singapore, Singapore; National University Cancer Institute, National University Health System, Singapore; Faculté de Medicine, University of Paris, Paris, France.
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11
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Kang SM, Yoon MH, Lee SJ, Ahn J, Yi SA, Nam KH, Park S, Woo TG, Cho JH, Lee J, Ha NC, Park BJ. Human WRN is an intrinsic inhibitor of progerin, abnormal splicing product of lamin A. Sci Rep 2021; 11:9122. [PMID: 33907225 PMCID: PMC8079706 DOI: 10.1038/s41598-021-88325-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 04/09/2021] [Indexed: 02/07/2023] Open
Abstract
Werner syndrome (WRN) is a rare progressive genetic disorder, caused by functional defects in WRN protein and RecQ4L DNA helicase. Acceleration of the aging process is initiated at puberty and the expected life span is approximately the late 50 s. However, a Wrn-deficient mouse model does not show premature aging phenotypes or a short life span, implying that aging processes differ greatly between humans and mice. Gene expression analysis of WRN cells reveals very similar results to gene expression analysis of Hutchinson Gilford progeria syndrome (HGPS) cells, suggesting that these human progeroid syndromes share a common pathological mechanism. Here we show that WRN cells also express progerin, an abnormal variant of the lamin A protein. In addition, we reveal that duplicated sequences of human WRN (hWRN) from exon 9 to exon 10, which differ from the sequence of mouse WRN (mWRN), are a natural inhibitor of progerin. Overexpression of hWRN reduced progerin expression and aging features in HGPS cells. Furthermore, the elimination of progerin by siRNA or a progerin-inhibitor (SLC-D011 also called progerinin) can ameliorate senescence phenotypes in WRN fibroblasts and cardiomyocytes, derived from WRN-iPSCs. These results suggest that progerin, which easily accumulates under WRN-deficient conditions, can lead to premature aging in WRN and that this effect can be prevented by SLC-D011.
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Affiliation(s)
- So-Mi Kang
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Min-Ho Yoon
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Su-Jin Lee
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Jinsook Ahn
- Program in Food Science and Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Sang Ah Yi
- School of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-Do, Republic of Korea
| | - Ki Hong Nam
- School of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-Do, Republic of Korea
| | - Soyoung Park
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Tae-Gyun Woo
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Jung-Hyun Cho
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea
| | - Jaecheol Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-Do, Republic of Korea
| | - Nam-Chul Ha
- Program in Food Science and Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Bum-Joon Park
- Department of Molecular Biology, Pusan National University, Busan, Republic of Korea.
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12
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Sir4 Deficiency Reverses Cell Senescence by Sub-Telomere Recombination. Cells 2021; 10:cells10040778. [PMID: 33915984 PMCID: PMC8066019 DOI: 10.3390/cells10040778] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/27/2021] [Accepted: 03/30/2021] [Indexed: 01/14/2023] Open
Abstract
Telomere shortening results in cellular senescence and the regulatory mechanisms remain unclear. Here, we report that the sub-telomere regions facilitate telomere lengthening by homologous recombination, thereby attenuating senescence in yeast Saccharomyces cerevisiae. The telomere protein complex Sir3/4 represses, whereas Rif1 promotes, the sub-telomere Y' element recombination. Genetic disruption of SIR4 increases Y' element abundance and rescues telomere-shortening-induced senescence in a Rad51-dependent manner, indicating a sub-telomere regulatory switch in regulating organismal senescence by DNA recombination. Inhibition of the sub-telomere recombination requires Sir4 binding to perinuclear protein Mps3 for telomere perinuclear localization and transcriptional repression of the telomeric repeat-containing RNA TERRA. Furthermore, Sir4 repression of Y' element recombination is negatively regulated by Rif1 that mediates senescence-evasion induced by Sir4 deficiency. Thus, our results demonstrate a dual opposing control mechanism of sub-telomeric Y' element recombination by Sir3/4 and Rif1 in the regulation of telomere shortening and cell senescence.
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13
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Zhang Y, Shao C, Li H, Wu K, Gong L, Zheng Q, Dan J, Jia S, Tang X, Wu X, Luo Y. The Distinct Function of p21 Waf1/Cip1 With p16 Ink4a in Modulating Aging Phenotypes of Werner Syndrome by Affecting Tissue Homeostasis. Front Genet 2021; 12:597566. [PMID: 33633779 PMCID: PMC7901894 DOI: 10.3389/fgene.2021.597566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 01/11/2021] [Indexed: 12/04/2022] Open
Abstract
Human Werner syndrome (WS) is an autosomal recessive progeria disease. A mouse model of WS manifests the disease through telomere dysfunction-induced aging phenotypes, which might result from cell cycle control and cellular senescence. Both p21Waf1/Cip1 (p21, encoded by the Cdkn1a gene) and p16Ink4a (p16, encoded by the Ink4a gene) are cell cycle inhibitors and are involved in regulating two key pathways of cellular senescence. To test the effect of p21 and p16 deficiencies in WS, we crossed WS mice (DKO) with p21–/– or p16–/– mice to construct triple knockout (p21-TKO or p16-TKO) mice. By studying the survival curve, bone density, regenerative tissue (testis), and stem cell capacity (intestine), we surprisingly found that p21-TKO mice displayed accelerated premature aging compared with DKO mice, while p16-TKO mice showed attenuation of the aging phenotypes. The incidence of apoptosis and cellular senescence were upregulated in p21-TKO mice tissue and downregulated in p16-TKO mice. Surprisingly, cellular proliferation in p21-TKO mice tissue was also upregulated, and the p21-TKO mice did not show telomere shortening compared with age-matched DKO mice, although p16-TKO mice displayed obvious enhancement of telomere lengthening. Consistent with these phenotypes, the SIRT1-PGC1 pathway was upregulated in p16-TKO but downregulated in p21-TKO compared with DKO mouse embryo fibroblasts (MEFs). However, the DNA damage response pathway was highly activated in p21-TKO, but rescued in p16-TKO, compared with DKO MEFs. These data suggest that p21 protected the stem cell reservoir by regulating cellular proliferation and turnover at a proper rate and that p21 loss in WS activated fairly severe DNA damage responses (DDR), which might cause an abnormal increase in tissue homeostasis. On the other hand, p16 promoted cellular senescence by inhibiting cellular proliferation, and p16 deficiency released this barrier signal without causing severe DDR.
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Affiliation(s)
- Yongjin Zhang
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Chihao Shao
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Haili Li
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China.,Guizhou Provincial Key Laboratory of Pathogenesis & Drug Development on Common Chronic Diseases, School of Basic Medicine, Guizhou Medical University, Guiyang, China
| | - Kun Wu
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China.,Yunnan Provincial Institute of Digestive Disease, Department of Gastroenterology, First People's Hospital of Yunnan Province, Kunming, China
| | - Lixin Gong
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Quan Zheng
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Juhua Dan
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Shuting Jia
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Xiaodan Tang
- Yunnan Provincial Institute of Digestive Disease, Department of Gastroenterology, First People's Hospital of Yunnan Province, Kunming, China
| | - Xiaoming Wu
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China
| | - Ying Luo
- Laboratory of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, China.,Guizhou Provincial Key Laboratory of Pathogenesis & Drug Development on Common Chronic Diseases, School of Basic Medicine, Guizhou Medical University, Guiyang, China.,Yunnan Provincial Institute of Digestive Disease, Department of Gastroenterology, First People's Hospital of Yunnan Province, Kunming, China
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14
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Alternative paths to telomere elongation. Semin Cell Dev Biol 2020; 113:88-96. [PMID: 33293233 DOI: 10.1016/j.semcdb.2020.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 10/31/2020] [Accepted: 11/09/2020] [Indexed: 11/24/2022]
Abstract
Overcoming cellular senescence that is induced by telomere shortening is critical in tumorigenesis. A majority of cancers achieve telomere maintenance through telomerase expression. However, a subset of cancers takes an alternate route for elongating telomeres: recombination-based alternative lengthening of telomeres (ALT). Current evidence suggests that break-induced replication (BIR), independent of RAD51, underlies ALT telomere synthesis. However, RAD51-dependent homologous recombination is required for homology search and inter-chromosomal telomere recombination in human ALT cancer cell maintenance. Accumulating evidence suggests that the breakdown of stalled replication forks, the replication stress, induces BIR at telomeres. Nevertheless, ALT research is still in its early stage and a comprehensive view is still unclear. Here, we review the current findings regarding the genesis of ALT, how this recombinant pathway is chosen, the epigenetic regulation of telomeres in ALT, and perspectives for clinical applications with the hope that this overview will generate new questions.
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15
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Dhar S, Datta A, Brosh RM. DNA helicases and their roles in cancer. DNA Repair (Amst) 2020; 96:102994. [PMID: 33137625 DOI: 10.1016/j.dnarep.2020.102994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/15/2022]
Abstract
DNA helicases, known for their fundamentally important roles in genomic stability, are high profile players in cancer. Not only are there monogenic helicase disorders with a strong disposition to cancer, it is well appreciated that helicase variants are associated with specific cancers (e.g., breast cancer). Flipping the coin, DNA helicases are frequently overexpressed in cancerous tissues and reduction in helicase gene expression results in reduced proliferation and growth capacity, as well as DNA damage induction and apoptosis of cancer cells. The seminal roles of helicases in the DNA damage and replication stress responses, as well as DNA repair pathways, validate their vital importance in cancer biology and suggest their potential values as targets in anti-cancer therapy. In recent years, many laboratories have characterized the specialized roles of helicase to resolve transcription-replication conflicts, maintain telomeres, mediate cell cycle checkpoints, remodel stalled replication forks, and regulate transcription. In vivo models, particularly mice, have been used to interrogate helicase function and serve as a bridge for preclinical studies that may lead to novel therapeutic approaches. In this review, we will summarize our current knowledge of DNA helicases and their roles in cancer, emphasizing the latest developments.
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Affiliation(s)
- Srijita Dhar
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Arindam Datta
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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16
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Datta A, Dhar S, Awate S, Brosh RM. Synthetic Lethal Interactions of RECQ Helicases. Trends Cancer 2020; 7:146-161. [PMID: 33041245 DOI: 10.1016/j.trecan.2020.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/20/2020] [Accepted: 09/04/2020] [Indexed: 02/06/2023]
Abstract
DNA helicases have risen to the forefront as genome caretakers. Their prominent roles in chromosomal stability are demonstrated by the linkage of mutations in helicase genes to hereditary disorders with defects in DNA repair, the replication stress response, and/or transcriptional activation. Conversely, accumulating evidence suggests that DNA helicases in cancer cells have a network of pathway interactions such that codeficiency of some helicases and their genetically interacting proteins results in synthetic lethality (SL). Such genetic interactions may potentially be exploited for cancer therapies. We discuss the roles of RECQ DNA helicases in cancer, emphasizing some of the more recent developments in SL.
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Affiliation(s)
- Arindam Datta
- Section on DNA Helicases, Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Srijita Dhar
- Section on DNA Helicases, Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Sanket Awate
- Section on DNA Helicases, Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Section on DNA Helicases, Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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17
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High homocysteine promotes telomere dysfunction and chromosomal instability in human neuroblastoma SH-SY5Y cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2020; 854-855:503197. [PMID: 32660821 DOI: 10.1016/j.mrgentox.2020.503197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 12/29/2022]
Abstract
Telomeres, specialized structures at the ends of linear chromosomes, protect chromosome ends from degradation, recombination, and mis-repair. Critically short telomere length (TL) may result in chromosome instability (CIN), causing tumor promotion and, at higher levels, cell death and tumor suppression. Homocysteine (Hcy) is a sulfur-containing amino acid involved in one-carbon metabolism. Elevated plasma Hcy is a cancer risk factor. Human SH-SY5Y neuroblastoma cells were treated with pathophysiological concentrations of Hcy (15-120 μM) for 14 and 28 days. The cytokinesis-block micronucleus cytome assay was used to determine cytostasis (nuclear division index, NDI), cell death (apoptosis and necrosis), and CIN (micronuclei, nucleoplasmic bridges, and nuclear buds in binucleated cells). Quantitative PCR was used to measure TL and the expression of hTERT, the gene encoding the catalytic subunit of telomerase for TL elongation. The results showed that Hcy induced elongation of TL and fluctuating changes in expression of hTERT. TL elongation was associated with increased CIN. Hcy decreased the NDI and increased cell death. This study shows that there is cross-talk between Hcy and TL in tumor cells and supports the concept that high Hcy inhibits cell division and promotes the death of tumor cells by abnormal elongation of TL and elevation of CIN.
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18
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Tomáška Ľ, Cesare AJ, AlTurki TM, Griffith JD. Twenty years of t-loops: A case study for the importance of collaboration in molecular biology. DNA Repair (Amst) 2020; 94:102901. [PMID: 32620538 DOI: 10.1016/j.dnarep.2020.102901] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 06/22/2020] [Indexed: 12/12/2022]
Abstract
Collaborative studies open doors to breakthroughs otherwise unattainable by any one laboratory alone. Here we describe the initial collaboration between the Griffith and de Lange laboratories that led to thinking about the telomere as a DNA template for homologous recombination, the proposal of telomere looping, and the first electron micrographs of t-loops. This was followed by collaborations that revealed t-loops across eukaryotic phyla. The Griffith and Tomáška/Nosek collaboration revealed circular telomeric DNA (t-circles) derived from the linear mitochondrial chromosomes of nonconventional yeast, which spurred discovery of t-circles in ALT-positive human cells. Collaborative work between the Griffith and McEachern labs demonstrated t-loops and t-circles in a series of yeast species. The de Lange and Zhuang laboratories then applied super-resolution light microscopy to demonstrate a genetic role for TRF2 in loop formation. Recent work from the Griffith laboratory linked telomere transcription with t-loop formation, providing a new model of the t-loop junction. A recent collaboration between the Cesare and Gaus laboratories utilized super-resolution light microscopy to provide details about t-loops as protective elements, followed by the Boulton and Cesare laboratories showing how cell cycle regulation of TRF2 and RTEL enables t-loop opening and reformation to promote telomere replication. Twenty years after the discovery of t-loops, we reflect on the collective history of their research as a case study in collaborative molecular biology.
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Affiliation(s)
- Ľubomír Tomáška
- Department of Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovicova 6, 84215, Bratislava, Slovakia
| | - Anthony J Cesare
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW, 2145, Australia
| | - Taghreed M AlTurki
- Lineberger Comprehensive Cancer Center and Departments of Microbiology and Immunology, and Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center and Departments of Microbiology and Immunology, and Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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19
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Brosh RM, Matson SW. History of DNA Helicases. Genes (Basel) 2020; 11:genes11030255. [PMID: 32120966 PMCID: PMC7140857 DOI: 10.3390/genes11030255] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 12/13/2022] Open
Abstract
Since the discovery of the DNA double helix, there has been a fascination in understanding the molecular mechanisms and cellular processes that account for: (i) the transmission of genetic information from one generation to the next and (ii) the remarkable stability of the genome. Nucleic acid biologists have endeavored to unravel the mysteries of DNA not only to understand the processes of DNA replication, repair, recombination, and transcription but to also characterize the underlying basis of genetic diseases characterized by chromosomal instability. Perhaps unexpectedly at first, DNA helicases have arisen as a key class of enzymes to study in this latter capacity. From the first discovery of ATP-dependent DNA unwinding enzymes in the mid 1970's to the burgeoning of helicase-dependent pathways found to be prevalent in all kingdoms of life, the story of scientific discovery in helicase research is rich and informative. Over four decades after their discovery, we take this opportunity to provide a history of DNA helicases. No doubt, many chapters are left to be written. Nonetheless, at this juncture we are privileged to share our perspective on the DNA helicase field - where it has been, its current state, and where it is headed.
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Affiliation(s)
- Robert M. Brosh
- Section on DNA Helicases, Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
- Correspondence: (R.M.B.J.); (S.W.M.); Tel.: +1-410-558-8578 (R.M.B.J.); +1-919-962-0005 (S.W.M.)
| | - Steven W. Matson
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Correspondence: (R.M.B.J.); (S.W.M.); Tel.: +1-410-558-8578 (R.M.B.J.); +1-919-962-0005 (S.W.M.)
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20
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Lovejoy CA, Takai K, Huh MS, Picketts DJ, de Lange T. ATRX affects the repair of telomeric DSBs by promoting cohesion and a DAXX-dependent activity. PLoS Biol 2020; 18:e3000594. [PMID: 31895940 PMCID: PMC6959610 DOI: 10.1371/journal.pbio.3000594] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/14/2020] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
Alpha thalassemia/mental retardation syndrome X-linked chromatin remodeler (ATRX), a DAXX (death domain-associated protein) interacting protein, is often lost in cells using the alternative lengthening of telomeres (ALT) pathway, but it is not known how ATRX loss leads to ALT. We report that ATRX deletion from mouse cells altered the repair of telomeric double-strand breaks (DSBs) and induced ALT-like phenotypes, including ALT-associated promyelocytic leukemia (PML) bodies (APBs), telomere sister chromatid exchanges (T-SCEs), and extrachromosomal telomeric signals (ECTSs). Mechanistically, we show that ATRX affects telomeric DSB repair by promoting cohesion of sister telomeres and that loss of ATRX in ALT cells results in diminished telomere cohesion. In addition, we document a role for DAXX in the repair of telomeric DSBs. Removal of telomeric cohesion in combination with DAXX deficiency recapitulates all telomeric DSB repair phenotypes associated with ATRX loss. The data reveal that ATRX has an effect on telomeric DSB repair and that this role involves both telomere cohesion and a DAXX-dependent pathway.
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Affiliation(s)
- Courtney A. Lovejoy
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Kaori Takai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Michael S. Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - David J. Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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21
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Doksani Y. The Response to DNA Damage at Telomeric Repeats and Its Consequences for Telomere Function. Genes (Basel) 2019; 10:genes10040318. [PMID: 31022960 PMCID: PMC6523756 DOI: 10.3390/genes10040318] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/13/2019] [Accepted: 04/18/2019] [Indexed: 01/17/2023] Open
Abstract
Telomeric repeats, coated by the shelterin complex, prevent inappropriate activation of the DNA damage response at the ends of linear chromosomes. Shelterin has evolved distinct solutions to protect telomeres from different aspects of the DNA damage response. These solutions include formation of t-loops, which can sequester the chromosome terminus from DNA-end sensors and inhibition of key steps in the DNA damage response. While blocking the DNA damage response at chromosome ends, telomeres make wide use of many of its players to deal with exogenous damage and replication stress. This review focuses on the interplay between the end-protection functions and the response to DNA damage occurring inside the telomeric repeats, as well as on the consequences that telomere damage has on telomere structure and function.
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Affiliation(s)
- Ylli Doksani
- IFOM, The FIRC Institute of Molecular Oncology, via Adamello 16, 20139 Milan, Italy.
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22
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Li H, Wei C, Zhou R, Wang B, Zhang Y, Shao C, Luo Y. Mouse models in modeling aging and cancer. Exp Gerontol 2019; 120:88-94. [PMID: 30876950 DOI: 10.1016/j.exger.2019.03.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/19/2019] [Accepted: 03/05/2019] [Indexed: 02/04/2023]
Abstract
Mouse models have been widely used in the research of human diseases. Aging, just as cancer, is influenced by the interaction of various genetic and environmental factors. Currently, aging could be induced by many mechanism, including telomere dysfunction, oxidase stress, DNA damage and epigenetic changes. Many of these genetic pathways are also shared by aging and cancer. The mouse models generated to study these pathways might manifest either aging or cancer phenotypes, sometimes both, which in deed has worked as a good model system in understanding the correlation between aging and cancer. Here, we reviewed these mouse models that were generated to model aging or cancer. These mouse models might help us put those related pathways in context and discover essential interactions in cancer and aging regulation.
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Affiliation(s)
- Haili Li
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China; Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Chuanyu Wei
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Ruoyu Zhou
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China; Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Boyuan Wang
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Yongjin Zhang
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Chihao Shao
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Ying Luo
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China; Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
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23
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Kwon M, Lee JJ, Min J, Hwang K, Park SG, Kim E, Kim BC, Bhak J, Lee H. Brca2 abrogation engages with the alternative lengthening of telomeres via break‐induced replication. FEBS J 2019; 286:1841-1858. [DOI: 10.1111/febs.14796] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/21/2019] [Accepted: 02/25/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Mi‐Sun Kwon
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Jennifer J. Lee
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Jaewon Min
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Kwangwoo Hwang
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Seung Gu Park
- Department of Biomedical Engineering UNIST Ulsan Korea
| | - Eun‐Hye Kim
- Department of Biomedical Engineering UNIST Ulsan Korea
| | | | - Jong Bhak
- Department of Biomedical Engineering UNIST Ulsan Korea
- Clinomics Inc. Ulsan Korea
| | - Hyunsook Lee
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
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Lerner LK, Sale JE. Replication of G Quadruplex DNA. Genes (Basel) 2019; 10:genes10020095. [PMID: 30700033 PMCID: PMC6409989 DOI: 10.3390/genes10020095] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 01/03/2023] Open
Abstract
A cursory look at any textbook image of DNA replication might suggest that the complex machine that is the replisome runs smoothly along the chromosomal DNA. However, many DNA sequences can adopt non-B form secondary structures and these have the potential to impede progression of the replisome. A picture is emerging in which the maintenance of processive DNA replication requires the action of a significant number of additional proteins beyond the core replisome to resolve secondary structures in the DNA template. By ensuring that DNA synthesis remains closely coupled to DNA unwinding by the replicative helicase, these factors prevent impediments to the replisome from causing genetic and epigenetic instability. This review considers the circumstances in which DNA forms secondary structures, the potential responses of the eukaryotic replisome to these impediments in the light of recent advances in our understanding of its structure and operation and the mechanisms cells deploy to remove secondary structure from the DNA. To illustrate the principles involved, we focus on one of the best understood DNA secondary structures, G quadruplexes (G4s), and on the helicases that promote their resolution.
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Affiliation(s)
- Leticia Koch Lerner
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Julian E Sale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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Datta A, Brosh RM. New Insights Into DNA Helicases as Druggable Targets for Cancer Therapy. Front Mol Biosci 2018; 5:59. [PMID: 29998112 PMCID: PMC6028597 DOI: 10.3389/fmolb.2018.00059] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/06/2018] [Indexed: 12/28/2022] Open
Abstract
Small molecules that deter the functions of DNA damage response machinery are postulated to be useful for enhancing the DNA damaging effects of chemotherapy or ionizing radiation treatments to combat cancer by impairing the proliferative capacity of rapidly dividing cells that accumulate replicative lesions. Chemically induced or genetic synthetic lethality is a promising area in personalized medicine, but it remains to be optimized. A new target in cancer therapy is DNA unwinding enzymes known as helicases. Helicases play critical roles in all aspects of nucleic acid metabolism. We and others have investigated small molecule targeted inhibition of helicase function by compound screens using biochemical and cell-based approaches. Small molecule-induced trapping of DNA helicases may represent a generalized mechanism exemplified by certain topoisomerase and PARP inhibitors that exert poisonous consequences, especially in rapidly dividing cancer cells. Taking the lead from the broader field of DNA repair inhibitors and new information gleaned from structural and biochemical studies of DNA helicases, we predict that an emerging strategy to identify useful helicase-interacting compounds will be structure-based molecular docking interfaced with a computational approach. Potency, specificity, drug resistance, and bioavailability of helicase inhibitor drugs and targeting such compounds to subcellular compartments where the respective helicases operate must be addressed. Beyond cancer therapy, continued and new developments in this area may lead to the discovery of helicase-interacting compounds that chemically rescue clinically relevant helicase missense mutant proteins or activate the catalytic function of wild-type DNA helicases, which may have novel therapeutic application.
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Affiliation(s)
- Arindam Datta
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD, United States
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, MD, United States
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De Vitis M, Berardinelli F, Sgura A. Telomere Length Maintenance in Cancer: At the Crossroad between Telomerase and Alternative Lengthening of Telomeres (ALT). Int J Mol Sci 2018; 19:ijms19020606. [PMID: 29463031 PMCID: PMC5855828 DOI: 10.3390/ijms19020606] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 02/07/2023] Open
Abstract
Eukaryotic cells undergo continuous telomere shortening as a consequence of multiple rounds of replications. During tumorigenesis, cells have to acquire telomere DNA maintenance mechanisms (TMMs) in order to counteract telomere shortening, to preserve telomeres from DNA damage repair systems and to avoid telomere-mediated senescence and/or apoptosis. For this reason, telomere maintenance is an essential step in cancer progression. Most human tumors maintain their telomeres expressing telomerase, whereas a lower but significant proportion activates the alternative lengthening of telomeres (ALT) pathway. However, evidence about the coexistence of ALT and telomerase has been found both in vivo in the same cancer populations and in vitro in engineered cellular models, making the distinction between telomerase- and ALT-positive tumors elusive. Indeed, after the development of drugs able to target telomerase, the capability for some cancer cells to escape death, switching from telomerase to ALT, was highlighted. Unfortunately, to date, the mechanism underlying the possible switching or the coexistence of telomerase and ALT within the same cell or populations is not completely understood and different factors could be involved. In recent years, different studies have tried to shed light on the complex regulation network that controls the transition between the two TMMs, suggesting a role for embryonic cancer origin, epigenetic modifications, and specific genes activation—both in vivo and in vitro. In this review, we examine recent findings about the cancer-associated differential activation of the two known TMMs and the possible factors implicated in this process. Furthermore, some studies on cancers are also described that did not display any TMM.
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Affiliation(s)
- Marco De Vitis
- Department of Science, Roma Tre University, 00146 Rome, Italy.
| | | | - Antonella Sgura
- Department of Science, Roma Tre University, 00146 Rome, Italy.
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Si X, Shao C, Li J, Jia S, Tang W, Zhang J, Yang J, Wu X, Luo Y. Loss of p21 promoted tumorigenesis in the background of telomere dysfunctions induced by TRF2 and Wrn deficiency. Int J Biol Sci 2018; 14:165-177. [PMID: 29483835 PMCID: PMC5821038 DOI: 10.7150/ijbs.23477] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/10/2017] [Indexed: 01/01/2023] Open
Abstract
Werner syndrome (WS) is a rare autosomal recessive progeria disease with genetic instability/cancer predisposition, thus a good model in understanding aging related carcinogenesis. Telomere dysfunction induced cellular senescence is essential in the manifestation of the WS phenotype. Our previous data has shown that p21 (encoded by Cdkn1a gene) could induce cellular senescence and suppress cellular growth of ALT (alternative lengthening of telomere) tumors derived from WS, suggested that p21 might play a key role in maintaining senescence of WS cells. To confirm the role of p21 in suppressing telomere dysfunction induced tumorigenesis, we overexpressed dominant negative protein TRF2ΔBΔM in p21-/- mouse embryonic fibroblasts (MEFs). To further stress the cell, we crossed Wrn-/-mice with p21-/- mice to obtained p21-/-Wrn-/- MEFs, and overexpressed TRF2ΔBΔM in these MEFs to induce telomere dysfunction similar to that in WS cells. Our data showed that, in the context of p21-/-TRF2ΔBΔM, loss of p21 function rescued cellular senescence, and induced p53 mutation, but did not induce tumorigenesis. However, in the set of p21-/-Wrn-/-TRF2ΔBΔM, loss of p21 function induced p53 mutation and tumorigenesis. To further verify the role of p21 in suppressing telomere dysfunction related tumorigenesis, we knocked down p21 in non-tumorigenic immortalized cells derived from WS MEFs (mTerc-/-Wrn-/-), and found that loss of p21 could induce ALT tumorigenesis, which displayed typical smear pattern of telomere length and arc-shaped telomeric DNA. In another hand, recovering telomerase activity in these MEFs could also induce tumorigenesis without affecting p21 expression level. Together our data suggested that p21 controlled cell cycle regulation played an essential role in suppressing telomere dysfunction-related tumorigenesis. These data also suggested that the genetic context is essential in determining the role of p21 in cancer prevention. Therefore, targeting p21 in the treatment of human degenerative diseases would require a personalized genetic background screen.
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Affiliation(s)
- Xiaoyu Si
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500.,College of Biological Engineering, Qilu University of Technology (Shandong Academy of Sciences), 3501 University Road, Changqing County, Jinan, Shandong Province, China, 250353
| | - Chihao Shao
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Jing Li
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500.,Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Shuting Jia
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Wenru Tang
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Jihong Zhang
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Julun Yang
- Faculty of Environmental Science and Engineering, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Xiaoming Wu
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500
| | - Ying Luo
- Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500.,College of Biological Engineering, Qilu University of Technology (Shandong Academy of Sciences), 3501 University Road, Changqing County, Jinan, Shandong Province, China, 250353.,Department of Pathology, Kunming General Hospital, 212 Daguan Road, Kunming, Yunnan Province, China, 650032
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28
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RecQ and Fe-S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions. Biochem Soc Trans 2017; 46:77-95. [PMID: 29273621 DOI: 10.1042/bst20170044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022]
Abstract
Helicases are molecular motors that play central roles in nucleic acid metabolism. Mutations in genes encoding DNA helicases of the RecQ and iron-sulfur (Fe-S) helicase families are linked to hereditary disorders characterized by chromosomal instabilities, highlighting the importance of these enzymes. Moreover, mono-allelic RecQ and Fe-S helicase mutations are associated with a broad spectrum of cancers. This review will discuss and contrast the specialized molecular functions and biological roles of RecQ and Fe-S helicases in DNA repair, the replication stress response, and the regulation of gene expression, laying a foundation for continued research in these important areas of study.
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Gunes C, Avila AI, Rudolph KL. Telomeres in cancer. Differentiation 2017; 99:41-50. [PMID: 29291448 DOI: 10.1016/j.diff.2017.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 02/07/2023]
Abstract
Telomere shortening as a consequence of cell divisions during aging and chronic diseases associates with an increased cancer risk. Experimental data revealed that telomere shortening results in telomere dysfunction, which in turn affects tumorigenesis in two ways. First, telomere dysfunction suppresses tumor progression by the activation of DNA damage checkpoints, which induce cell cycle arrest (senescence) or apoptosis, as well as by inducing metabolic compromise and activation of immune responses directed against senescent cells. Second, telomere dysfunction promotes tumorigenesis by inducing chromosomal instability in tumor initiating cells, by inhibiting proliferative competition of non-transformed cells, and possibly, also by influencing tumor cell plasticity. The tumor promoting effects of telomere dysfunction are context dependent and require the loss of p53-dependent DNA damage checkpoints or other genetic modifiers that attenuate DNA damage responses possibly involving complex interactions of different genes. The activation of telomere stabilizing mechanisms appears as a subsequent step, which is required to enable immortal grotwh of emerging cancer cells. Here, we conceptually discuss our current knowledge and new, unpublished experimental data on telomere dependent influences on tumor initiation and progression.
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Affiliation(s)
| | - Alush Irene Avila
- Research Group on Stem Cell Aging, Leibniz Institute on Aging, Fritz Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - K Lenhard Rudolph
- Research Group on Stem Cell Aging, Leibniz Institute on Aging, Fritz Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany.
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30
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Abstract
Aging, the universal phenomenon, affects human health and is the primary risk factor for major disease pathologies. Progeroid diseases, which mimic aging at an accelerated rate, have provided cues in understanding the hallmarks of aging. Mutations in DNA repair genes as well as in telomerase subunits are known to cause progeroid syndromes. Werner syndrome (WS), which is characterized by accelerated aging, is an autosomal-recessive genetic disorder. Hallmarks that define the aging process include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulation of nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. WS recapitulates these hallmarks of aging and shows increased incidence and early onset of specific cancers. Genome integrity and stability ensure the normal functioning of the cell and are mainly guarded by the DNA repair machinery and telomeres. WRN, being a RecQ helicase, protects genome stability by regulating DNA repair pathways and telomeres. Recent advances in WS research have elucidated WRN’s role in DNA repair pathway choice regulation, telomere maintenance, resolution of complex DNA structures, epigenetic regulation, and stem cell maintenance.
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Affiliation(s)
- Raghavendra A Shamanna
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Jong-Hyuk Lee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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31
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Crouch JD, Brosh RM. Mechanistic and biological considerations of oxidatively damaged DNA for helicase-dependent pathways of nucleic acid metabolism. Free Radic Biol Med 2017; 107:245-257. [PMID: 27884703 PMCID: PMC5440220 DOI: 10.1016/j.freeradbiomed.2016.11.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/11/2016] [Accepted: 11/13/2016] [Indexed: 12/21/2022]
Abstract
Cells are under constant assault from reactive oxygen species that occur endogenously or arise from environmental agents. An important consequence of such stress is the generation of oxidatively damaged DNA, which is represented by a wide range of non-helix distorting and helix-distorting bulkier lesions that potentially affect a number of pathways including replication and transcription; consequently DNA damage tolerance and repair pathways are elicited to help cells cope with the lesions. The cellular consequences and metabolism of oxidatively damaged DNA can be quite complex with a number of DNA metabolic proteins and pathways involved. Many of the responses to oxidative stress involve a specialized class of enzymes known as helicases, the topic of this review. Helicases are molecular motors that convert the energy of nucleoside triphosphate hydrolysis to unwinding of structured polynucleic acids. Helicases by their very nature play fundamentally important roles in DNA metabolism and are implicated in processes that suppress chromosomal instability, genetic disease, cancer, and aging. We will discuss the roles of helicases in response to nuclear and mitochondrial oxidative stress and how this important class of enzymes help cells cope with oxidatively generated DNA damage through their functions in the replication stress response, DNA repair, and transcriptional regulation.
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Affiliation(s)
- Jack D Crouch
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA.
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32
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Wu PF, Jin JY, Li JJ, He JQ, Fan LL, Jin M, Huang H, Xia K, Tang JY, Xiang R. A novel splice-site mutation of WRN (c.IVS28+2T>C) identified in a consanguineous family with Werner Syndrome. Mol Med Rep 2017; 15:3735-3738. [DOI: 10.3892/mmr.2017.6465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 01/16/2017] [Indexed: 11/06/2022] Open
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DNA Replication Origins and Fork Progression at Mammalian Telomeres. Genes (Basel) 2017; 8:genes8040112. [PMID: 28350373 PMCID: PMC5406859 DOI: 10.3390/genes8040112] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions.
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The Werner Syndrome Helicase Coordinates Sequential Strand Displacement and FEN1-Mediated Flap Cleavage during Polymerase δ Elongation. Mol Cell Biol 2017; 37:MCB.00560-16. [PMID: 27849570 DOI: 10.1128/mcb.00560-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/08/2016] [Indexed: 02/01/2023] Open
Abstract
The Werner syndrome protein (WRN) suppresses the loss of telomeres replicated by lagging-strand synthesis by a yet to be defined mechanism. Here, we show that whereas either WRN or the Bloom syndrome helicase (BLM) stimulates DNA polymerase δ progression across telomeric G-rich repeats, only WRN promotes sequential strand displacement synthesis and FEN1 cleavage, a critical step in Okazaki fragment maturation, at these sequences. Helicase activity, as well as the conserved winged-helix (WH) motif and the helicase and RNase D C-terminal (HRDC) domain play important but distinct roles in this process. Remarkably, WRN also influences the formation of FEN1 cleavage products during strand displacement on a nontelomeric substrate, suggesting that WRN recruitment and cooperative interaction with FEN1 during lagging-strand synthesis may serve to regulate sequential strand displacement and flap cleavage at other genomic sites. These findings define a biochemical context for the physiological role of WRN in maintaining genetic stability.
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Oshima J, Sidorova JM, Monnat RJ. Werner syndrome: Clinical features, pathogenesis and potential therapeutic interventions. Ageing Res Rev 2017; 33:105-114. [PMID: 26993153 PMCID: PMC5025328 DOI: 10.1016/j.arr.2016.03.002] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/09/2016] [Accepted: 03/11/2016] [Indexed: 12/20/2022]
Abstract
Werner syndrome (WS) is a prototypical segmental progeroid syndrome characterized by multiple features consistent with accelerated aging. It is caused by null mutations of the WRN gene, which encodes a member of the RECQ family of DNA helicases. A unique feature of the WRN helicase is the presence of an exonuclease domain in its N-terminal region. Biochemical and cell biological studies during the past decade have demonstrated involvements of the WRN protein in multiple DNA transactions, including DNA repair, recombination, replication and transcription. A role of the WRN protein in telomere maintenance could explain many of the WS phenotypes. Recent discoveries of new progeroid loci found in atypical Werner cases continue to support the concept of genomic instability as a major mechanism of biological aging. Based on these biological insights, efforts are underway to develop therapeutic interventions for WS and related progeroid syndromes.
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Affiliation(s)
- Junko Oshima
- Department of Pathology, University of Washington, Seattle, WA 98195, USA; Department of Medicine, Chiba University, Chiba, Japan.
| | - Julia M Sidorova
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Raymond J Monnat
- Department of Pathology, University of Washington, Seattle, WA 98195, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
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Shamanna RA, Lu H, de Freitas JK, Tian J, Croteau DL, Bohr VA. WRN regulates pathway choice between classical and alternative non-homologous end joining. Nat Commun 2016; 7:13785. [PMID: 27922005 PMCID: PMC5150655 DOI: 10.1038/ncomms13785] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 11/01/2016] [Indexed: 11/20/2022] Open
Abstract
Werner syndrome (WS) is an accelerated ageing disorder with genomic instability caused by WRN protein deficiency. Many features seen in WS can be explained by the diverse functions of WRN in DNA metabolism. However, the origin of the large genomic deletions and telomere fusions are not yet understood. Here, we report that WRN regulates the pathway choice between classical (c)- and alternative (alt)-nonhomologous end joining (NHEJ) during DNA double-strand break (DSB) repair. It promotes c-NHEJ via helicase and exonuclease activities and inhibits alt-NHEJ using non-enzymatic functions. When WRN is recruited to the DSBs it suppresses the recruitment of MRE11 and CtIP, and protects the DSBs from 5′ end resection. Moreover, knockdown of Wrn, alone or in combination with Trf2 in mouse embryonic fibroblasts results in increased telomere fusions, which were ablated by Ctip knockdown. We show that WRN regulates alt-NHEJ and shields DSBs from MRE11/CtIP-mediated resection to prevent large deletions and telomere fusions. Werner Syndrome is an accelerated aging disorder marked by genome instability, large deletions and telomere fusions, hallmarks of aberrant DNA repair. Here the authors report a role for the WRN helicase in regulating the choice between classical and alternative non-homologous end-joning.
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Affiliation(s)
- Raghavendra A Shamanna
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Huiming Lu
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Jessica K de Freitas
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Jane Tian
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
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37
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Kargaran PK, Yasaei H, Anjomani-Virmouni S, Mangiapane G, Slijepcevic P. Analysis of alternative lengthening of telomere markers in BRCA1 defective cells. Genes Chromosomes Cancer 2016; 55:864-76. [PMID: 27295426 PMCID: PMC5113789 DOI: 10.1002/gcc.22386] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 06/03/2016] [Accepted: 06/03/2016] [Indexed: 12/15/2022] Open
Abstract
Telomeres are specialized structures responsible for the chromosome end protection. Previous studies have revealed that defective BRCA1 may lead to elevated telomere fusions and accelerated telomere shortening. In addition, BRCA1 associates with promyelocytic leukemia (PML) bodies in alternative lengthening of telomeres (ALTs) positive cells. We report here elevated recombination rates at telomeres in cells from human BRCA1 mutation carriers and in mouse embryonic stem cells lacking both copies of functional Brca1. An increased recombination rate at telomeres is one of the signs of ALT. To investigate this possibility further we employed the C-circle assay that identifies ALT unequivocally. Our results revealed elevated levels of ALT activity in Brca1 defective mouse cells. Similar results were obtained when the same cells were assayed for the presence of another ALT marker, namely the frequency of PML bodies. These results suggest that BRCA1 may act as a repressor of ALT. © 2016 The Authors Genes, Chromosomes & Cancer Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Parisa K Kargaran
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
| | - Hemad Yasaei
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
| | - Sara Anjomani-Virmouni
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
| | - Giovanna Mangiapane
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
| | - Predrag Slijepcevic
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK.
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Yokote K, Chanprasert S, Lee L, Eirich K, Takemoto M, Watanabe A, Koizumi N, Lessel D, Mori T, Hisama FM, Ladd PD, Angle B, Baris H, Cefle K, Palanduz S, Ozturk S, Chateau A, Deguchi K, Easwar TKM, Federico A, Fox A, Grebe TA, Hay B, Nampoothiri S, Seiter K, Streeten E, Piña-Aguilar RE, Poke G, Poot M, Posmyk R, Martin GM, Kubisch C, Schindler D, Oshima J. WRN Mutation Update: Mutation Spectrum, Patient Registries, and Translational Prospects. Hum Mutat 2016; 38:7-15. [PMID: 27667302 DOI: 10.1002/humu.23128] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/16/2016] [Accepted: 09/20/2016] [Indexed: 12/19/2022]
Abstract
Werner syndrome (WS) is a rare autosomal recessive disorder characterized by a constellation of adult onset phenotypes consistent with an acceleration of intrinsic biological aging. It is caused by pathogenic variants in the WRN gene, which encodes a multifunctional nuclear protein with exonuclease and helicase activities. WRN protein is thought to be involved in optimization of various aspects of DNA metabolism, including DNA repair, recombination, replication, and transcription. In this update, we summarize a total of 83 different WRN mutations, including eight previously unpublished mutations identified by the International Registry of Werner Syndrome (Seattle, WA) and the Japanese Werner Consortium (Chiba, Japan), as well as 75 mutations already reported in the literature. The Seattle International Registry recruits patients from all over the world to investigate genetic causes of a wide variety of progeroid syndromes in order to contribute to the knowledge of basic mechanisms of human aging. Given the unusually high prevalence of WS patients and heterozygous carriers in Japan, the major goal of the Japanese Consortium is to develop effective therapies and to establish management guidelines for WS patients in Japan and elsewhere. This review will also discuss potential translational approaches to this disorder, including those currently under investigation.
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Affiliation(s)
- Koutaro Yokote
- Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Sirisak Chanprasert
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, Washington
| | - Lin Lee
- Department of Pathology, University of Washington, Seattle, Washington
| | - Katharina Eirich
- Department of Human Genetics, University of Wuerzburg, Wuerzburg, Germany
| | - Minoru Takemoto
- Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Aki Watanabe
- Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Naoko Koizumi
- Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Davor Lessel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Takayasu Mori
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, Washington
| | - Fuki M Hisama
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, Washington
| | - Paula D Ladd
- Department of Pathology, University of Washington, Seattle, Washington
| | - Brad Angle
- Advocate Lutheran General Hospital and Advocate Children's Hospital, Park Ridge, Illinois
| | - Hagit Baris
- The Genetics Institute, Rambam Health Care Campus and Rappaport School of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Kivanc Cefle
- Department of Internal Medicine, Division of Medical Genetics, Istanbul Medical Faculty, Istanbul University, Turkey
| | - Sukru Palanduz
- Department of Internal Medicine, Division of Medical Genetics, Istanbul Medical Faculty, Istanbul University, Turkey
| | - Sukru Ozturk
- Department of Internal Medicine, Division of Medical Genetics, Istanbul Medical Faculty, Istanbul University, Turkey
| | - Antoinette Chateau
- Department of Dermatology, Greys Hospital, Pietermaritzburg, South Africa
| | - Kentaro Deguchi
- Department of Neurology, Okayama City Hospital, Okayama, Japan
| | | | - Antonio Federico
- Department of Medicine, Surgery and Neurosciences, Unit Clinical Neurology and Neurometabolic Diseases, Medical School, University of Siena, Siena, Italy
| | - Amy Fox
- Department of Dermatology, University of North Carolina, Chapel Hill, North Carolina
| | - Theresa A Grebe
- Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, Arizona
| | - Beverly Hay
- Division of Genetics, UMass Memorial Medical Center, Worcester, Massachusetts
| | - Sheela Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences and Research Center, Kochi, Kerala, India
| | - Karen Seiter
- Department of Medicine, New York Medical College, Hawthorne, New York
| | - Elizabeth Streeten
- Division of Genetics, University of Maryland School of Medicine, Baltimore, Maryland
| | | | - Gemma Poke
- Genetic Health Service NZ, Wellington, New Zealand
| | - Martin Poot
- University Medical Center, Utrecht, Netherlands
| | - Renata Posmyk
- Department of Clinical Genetics, Podlaskie Medical Center, Bialystok, Poland
- Department of Perinatology, Medical University of Bialystok, Bialystok, Poland
| | - George M Martin
- Department of Pathology, University of Washington, Seattle, Washington
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Detlev Schindler
- Department of Human Genetics, University of Wuerzburg, Wuerzburg, Germany
| | - Junko Oshima
- Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Pathology, University of Washington, Seattle, Washington
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Tang W, Robles AI, Beyer RP, Gray LT, Nguyen GH, Oshima J, Maizels N, Harris CC, Monnat RJ. The Werner syndrome RECQ helicase targets G4 DNA in human cells to modulate transcription. Hum Mol Genet 2016; 25:2060-2069. [PMID: 26984941 DOI: 10.1093/hmg/ddw079] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/07/2016] [Indexed: 11/12/2022] Open
Abstract
The Werner syndrome (WS) is a prototypic adult Mendelian progeroid syndrome in which signs of premature aging are associated with genomic instability and an elevated risk of cancer. The WRN RECQ helicase protein binds and unwinds G-quadruplex (G4) DNA substrates in vitro, and we identified significant enrichment in G4 sequence motifs at the transcription start site and 5' ends of first introns (false discovery rate < 0.001) of genes down-regulated in WS patient fibroblasts. This finding provides strong evidence that WRN binds G4 DNA structures at many chromosomal sites to modulate gene expression. WRN appears to bind a distinct subpopulation of G4 motifs in human cells, when compared with the related Bloom syndrome RECQ helicase protein. Functional annotation of the genes and miRNAs altered in WS provided new insight into WS disease pathogenesis. WS patient fibroblasts displayed altered expression of multiple, mechanistically distinct, senescence-associated gene expression programs, with altered expression of disease-associated miRNAs, and dysregulation of canonical pathways that regulate cell signaling, genome stability and tumorigenesis. WS fibroblasts also displayed a highly statistically significant and distinct gene expression signature, with coordinate overexpression of nearly all of the cytoplasmic tRNA synthetases and associated ARS-interacting multifunctional protein genes. The 'non-canonical' functions of many of these upregulated tRNA charging proteins may together promote WS disease pathogenesis. Our results identify the human WRN RECQ protein as a G4 helicase that modulates gene expression in G4-dependent fashion at many chromosomal sites and provide several new and unexpected mechanistic insights into WS disease pathogenesis.
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Affiliation(s)
| | - Ana I Robles
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA and
| | | | | | - Giang H Nguyen
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Junko Oshima
- Department of Pathology, Department of Medicine, Chiba University, Chiba, Japan
| | - Nancy Maizels
- Department of Pathology, Department of Immunology, Department of Biochemistry
| | - Curtis C Harris
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Raymond J Monnat
- Department of Pathology, Department of Genome Sciences, University of Washington, Seattle, WA, USA,
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Spontaneous tumor development in bone marrow-rescued DNA-PKcs(3A/3A) mice due to dysfunction of telomere leading strand deprotection. Oncogene 2015; 35:3909-18. [PMID: 26616856 PMCID: PMC4885801 DOI: 10.1038/onc.2015.459] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 10/29/2015] [Accepted: 10/30/2015] [Indexed: 12/16/2022]
Abstract
Phosphorylation of the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) at the Thr2609 cluster is essential for its complete function in DNA repair and tissue stem cell homeostasis. This phenomenon is demonstrated by congenital bone marrow failure occurring in DNA-PKcs3A/3A mutant mice, which require bone marrow transplantation (BMT) to prevent early mortality. Surprisingly, an increased incidence of spontaneous tumors, especially skin cancer, was observed in adult BMT-rescued DNA-PKcs3A/3A mice. Upon further investigation we found that spontaneous γH2AX foci occurred in DNA-PKcs3A/3A skin biopsies and primary keratinocytes and that these foci overlapped with telomeres during mitosis, indicating impairment of telomere replication and maturation. Consistently, we observed significantly elevated frequencies of telomere fusion events in DNA-PKcs3A/3A cells as compared to wild type and DNA-PKcs knockout cells. In addition, a previously identified DNA-PKcs Thr2609Pro mutation, found in breast cancer, also induces a similar impairment of telomere leading end maturation. Taken together, our current analyses indicate that the functional DNA-PKcs T2609 cluster is required to facilitate telomere leading strand maturation and prevention of genomic instability and cancer development.
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Cheung HH, Pei D, Chan WY. Stem cell aging in adult progeria. ACTA ACUST UNITED AC 2015; 4:6. [PMID: 26435834 PMCID: PMC4592574 DOI: 10.1186/s13619-015-0021-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/29/2015] [Indexed: 12/21/2022]
Abstract
Aging is considered an irreversible biological process and also a major risk factor for a spectrum of geriatric diseases. Advanced age-related decline in physiological functions, such as neurodegeneration, development of cardiovascular disease, endocrine and metabolic dysfunction, and neoplastic transformation, has become the focus in aging research. Natural aging is not regarded as a programmed process. However, accelerated aging due to inherited genetic defects in patients of progeria is programmed and resembles many aspects of natural aging. Among several premature aging syndromes, Werner syndrome (WS) and Hutchinson–Gilford progeria syndrome (HGPS) are two broadly investigated diseases. In this review, we discuss how stem cell aging in WS helps us understand the biology of aging. We also discuss briefly how the altered epigenetic landscape in aged cells can be reversed to a “juvenile” state. Lastly, we explore the potential application of the latest genomic editing technique for stem cell-based therapy and regenerative medicine in the context of aging.
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Affiliation(s)
- Hoi-Hung Cheung
- CUHK-CAS GIBH Joint Research Laboratory on Stem Cell and Regenerative Medicine, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., China
| | - Duanqing Pei
- Chinese Academy of Sciences (CAS) Guangzhou Institutes of Biomedicine and Health (GIBH), Guangzhou, China
| | - Wai-Yee Chan
- CUHK-CAS GIBH Joint Research Laboratory on Stem Cell and Regenerative Medicine, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., China ; The Chinese University of Hong Kong, Room G03A, Lo Kwee-Seong Intergrated Biomedical Science Building, Shatin, N.T., Hong Kong S.A.R., China
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42
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The DNA structure and sequence preferences of WRN underlie its function in telomeric recombination events. Nat Commun 2015; 6:8331. [PMID: 26420422 PMCID: PMC4589872 DOI: 10.1038/ncomms9331] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/11/2015] [Indexed: 12/27/2022] Open
Abstract
Telomeric abnormalities caused by loss of function of the RecQ helicase WRN are linked to the multiple premature ageing phenotypes that characterize Werner syndrome. Here we examine WRN's role in telomeric maintenance, by comparing its action on a variety of DNA structures without or with telomeric sequences. Our results show that WRN clearly prefers to act on strand invasion intermediates in a manner that favours strand invasion and exchange. Moreover, WRN unwinding of these recombination structures is further enhanced when the invading strand contains at least three G-rich single-stranded telomeric repeats. These selectivities are most pronounced at NaCl concentrations within the reported intranuclear monovalent cation concentration range, and are partly conferred by WRN's C-terminal region. Importantly, WRN's specificity for the G-rich telomeric sequence within this precise structural context is particularly relevant to telomere metabolism and strongly suggests a physiological role in telomeric recombination processes, including T-loop dynamics.
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Ilicheva NV, Podgornaya OI, Voronin AP. Telomere Repeat-Binding Factor 2 Is Responsible for the Telomere Attachment to the Nuclear Membrane. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 101:67-96. [DOI: 10.1016/bs.apcsb.2015.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Acharya S, Kaul Z, Gocha AS, Martinez AR, Harris J, Parvin JD, Groden J. Association of BLM and BRCA1 during Telomere Maintenance in ALT Cells. PLoS One 2014; 9:e103819. [PMID: 25084169 PMCID: PMC4118958 DOI: 10.1371/journal.pone.0103819] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 07/07/2014] [Indexed: 11/18/2022] Open
Abstract
Fifteen percent of tumors utilize recombination-based alternative lengthening of telomeres (ALT) to maintain telomeres. The mechanisms underlying ALT are unclear but involve several proteins involved in homologous recombination including the BLM helicase, mutated in Bloom's syndrome, and the BRCA1 tumor suppressor. Cells deficient in either BLM or BRCA1 have phenotypes consistent with telomere dysfunction. Although BLM associates with numerous DNA damage repair proteins including BRCA1 during DNA repair, the functional consequences of BLM-BRCA1 association in telomere maintenance are not completely understood. Our earlier work showed the involvement of BRCA1 in different mechanisms of ALT, and telomere shortening upon loss of BLM in ALT cells. In order to delineate their roles in telomere maintenance, we studied their association in telomere metabolism in cells using ALT. This work shows that BLM and BRCA1 co-localize with RAD50 at telomeres during S- and G2-phases of the cell cycle in immortalized human cells using ALT but not in cells using telomerase to maintain telomeres. Co-immunoprecipitation of BRCA1 and BLM is enhanced in ALT cells at G2. Furthermore, BRCA1 and BLM interact with RAD50 predominantly in S- and G2-phases, respectively. Biochemical assays demonstrate that full-length BRCA1 increases the unwinding rate of BLM three-fold in assays using a DNA substrate that models a forked structure composed of telomeric repeats. Our results suggest that BRCA1 participates in ALT through its interactions with RAD50 and BLM.
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Affiliation(s)
- Samir Acharya
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Zeenia Kaul
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - April Sandy Gocha
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Alaina R. Martinez
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Julia Harris
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Jeffrey D. Parvin
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Joanna Groden
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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45
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Edwards DN, Orren DK, Machwe A. Strand exchange of telomeric DNA catalyzed by the Werner syndrome protein (WRN) is specifically stimulated by TRF2. Nucleic Acids Res 2014; 42:7748-61. [PMID: 24880691 PMCID: PMC4081078 DOI: 10.1093/nar/gku454] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Werner syndrome (WS), caused by loss of function of the RecQ helicase WRN, is a hereditary disease characterized by premature aging and elevated cancer incidence. WRN has DNA binding, exonuclease, ATPase, helicase and strand annealing activities, suggesting possible roles in recombination-related processes. Evidence indicates that WRN deficiency causes telomeric abnormalities that likely underlie early onset of aging phenotypes in WS. Furthermore, TRF2, a protein essential for telomere protection, interacts with WRN and influences its basic helicase and exonuclease activities. However, these studies provided little insight into WRN's specific function at telomeres. Here, we explored the possibility that WRN and TRF2 cooperate during telomeric recombination processes. Our results indicate that TRF2, through its interactions with both WRN and telomeric DNA, stimulates WRN-mediated strand exchange specifically between telomeric substrates; TRF2's basic domain is particularly important for this stimulation. Although TRF1 binds telomeric DNA with similar affinity, it has minimal effects on WRN-mediated strand exchange of telomeric DNA. Moreover, TRF2 is displaced from telomeric DNA by WRN, independent of its ATPase and helicase activities. Together, these results suggest that TRF2 and WRN act coordinately during telomeric recombination processes, consistent with certain telomeric abnormalities associated with alteration of WRN function.
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Affiliation(s)
- Deanna N Edwards
- Graduate Center for Toxicology and Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - David K Orren
- Graduate Center for Toxicology and Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Amrita Machwe
- Graduate Center for Toxicology and Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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Gocha ARS, Acharya S, Groden J. WRN loss induces switching of telomerase-independent mechanisms of telomere elongation. PLoS One 2014; 9:e93991. [PMID: 24709898 PMCID: PMC3977986 DOI: 10.1371/journal.pone.0093991] [Citation(s) in RCA: 20] [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: 01/14/2014] [Accepted: 03/11/2014] [Indexed: 12/24/2022] Open
Abstract
Telomere maintenance can occur in the presence of telomerase or in its absence, termed alternative lengthening of telomeres (ALT). ALT adds telomere repeats using recombination-based processes and DNA repair proteins that function in homologous recombination. Our previous work reported that the RecQ-like BLM helicase is required for ALT and that it unwinds telomeric substrates in vitro. WRN is also a RecQ-like helicase that shares many biochemical functions with BLM. WRN interacts with BLM, unwinds telomeric substrates, and co-localizes to ALT-associated PML bodies (APBs), suggesting that it may also be required for ALT processes. Using long-term siRNA knockdown of WRN in three ALT cell lines, we show that some, but not all, cell lines require WRN for telomere maintenance. VA-13 cells require WRN to prevent telomere loss and for the formation of APBs; Saos-2 cells do not. A third ALT cell line, U-2 OS, requires WRN for APB formation, however WRN loss results in p53-mediated apoptosis. In the absence of WRN and p53, U-2 OS cells undergo telomere loss for an intermediate number of population doublings (50-70), at which point they maintain telomere length even with the continued loss of WRN. WRN and the tumor suppressor BRCA1 co-localize to APBs in VA-13 and U-2 OS, but not in Saos-2 cells. WRN loss in U-2 OS is associated with a loss of BRCA1 from APBs. While the loss of WRN significantly increases telomere sister chromatid exchanges (T-SCE) in these three ALT cell lines, loss of both BRCA1 and WRN does not significantly alter T-SCE. This work demonstrates that ALT cell lines use different telomerase-independent maintenance mechanisms that variably require the WRN helicase and that some cells can switch from one mechanism to another that permits telomere elongation in the absence of WRN. Our data suggest that BRCA1 localization may define these mechanisms.
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Affiliation(s)
- April Renee Sandy Gocha
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Samir Acharya
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Joanna Groden
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, Ohio, United States of America
- * E-mail:
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Cheung HH, Liu X, Canterel-Thouennon L, Li L, Edmonson C, Rennert OM. Telomerase protects werner syndrome lineage-specific stem cells from premature aging. Stem Cell Reports 2014; 2:534-46. [PMID: 24749076 PMCID: PMC3986587 DOI: 10.1016/j.stemcr.2014.02.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 02/20/2014] [Accepted: 02/20/2014] [Indexed: 12/12/2022] Open
Abstract
Werner syndrome (WS) patients exhibit premature aging predominantly in mesenchyme-derived tissues, but not in neural lineages, a consequence of telomere dysfunction and accelerated senescence. The cause of this lineage-specific aging remains unknown. Here, we document that reprogramming of WS fibroblasts to pluripotency elongated telomere length and prevented telomere dysfunction. To obtain mechanistic insight into the origin of tissue-specific aging, we differentiated iPSCs to mesenchymal stem cells (MSCs) and neural stem/progenitor cells (NPCs). We observed recurrence of premature senescence associated with accelerated telomere attrition and defective synthesis of the lagging strand telomeres in MSCs, but not in NPCs. We postulate this “aging” discrepancy is regulated by telomerase. Expression of hTERT or p53 knockdown ameliorated the accelerated aging phenotypein MSC, whereas inhibition of telomerase sensitized NPCs to DNA damage. Our findings unveil a role for telomerase in the protection of accelerated aging in a specific lineage of stem cells. Prevention of premature senescence with corrected telomeres in reprogrammed WS iPSCs Recurrence of premature senescence and telomere dysfunction in WS iPSC-derived MSCs Rescue of premature senescence in WS MSCs by hTERT overexpression or p53 depletion Telomerase protects and prevents NPCs from DNA damage
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Affiliation(s)
- Hoi-Hung Cheung
- Laboratory of Clinical and Developmental Genomics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA ; School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, N.T., 852 Hong Kong S.A.R
| | - Xiaozhuo Liu
- Laboratory of Clinical and Developmental Genomics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA ; School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, N.T., 852 Hong Kong S.A.R
| | - Lucile Canterel-Thouennon
- Laboratory of Clinical and Developmental Genomics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lu Li
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, N.T., 852 Hong Kong S.A.R
| | - Catherine Edmonson
- Laboratory of Clinical and Developmental Genomics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Owen M Rennert
- Laboratory of Clinical and Developmental Genomics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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48
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Popuri V, Hsu J, Khadka P, Horvath K, Liu Y, Croteau DL, Bohr VA. Human RECQL1 participates in telomere maintenance. Nucleic Acids Res 2014; 42:5671-88. [PMID: 24623817 PMCID: PMC4027191 DOI: 10.1093/nar/gku200] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A variety of human tumors employ alternative and recombination-mediated lengthening for telomere maintenance (ALT). Human RecQ helicases, such as BLM and WRN, can efficiently unwind alternate/secondary structures during telomere replication and/or recombination. Here, we report a novel role for RECQL1, the most abundant human RecQ helicase but functionally least studied, in telomere maintenance. RECQL1 associates with telomeres in ALT cells and actively resolves telomeric D-loops and Holliday junction substrates. RECQL1 physically and functionally interacts with telomere repeat-binding factor 2 that in turn regulates its helicase activity on telomeric substrates. The telomeric single-stranded binding protein, protection of telomeres 1 efficiently stimulates RECQL1 on telomeric substrates containing thymine glycol, a replicative blocking lesion. Loss of RECQL1 results in dysfunctional telomeres, telomere loss and telomere shortening, elevation of telomere sister-chromatid exchanges and increased aphidicolin-induced telomere fragility, indicating a role for RECQL1 in telomere maintenance. Further, our results indicate that RECQL1 may participate in the same pathway as WRN, probably in telomere replication.
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Affiliation(s)
- Venkateswarlu Popuri
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
| | - Joseph Hsu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
| | - Prabhat Khadka
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
| | - Kent Horvath
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
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Croteau DL, Popuri V, Opresko PL, Bohr VA. Human RecQ helicases in DNA repair, recombination, and replication. Annu Rev Biochem 2014; 83:519-52. [PMID: 24606147 DOI: 10.1146/annurev-biochem-060713-035428] [Citation(s) in RCA: 398] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
RecQ helicases are an important family of genome surveillance proteins conserved from bacteria to humans. Each of the five human RecQ helicases plays critical roles in genome maintenance and stability, and the RecQ protein family members are often referred to as guardians of the genome. The importance of these proteins in cellular homeostasis is underscored by the fact that defects in BLM, WRN, and RECQL4 are linked to distinct heritable human disease syndromes. Each human RecQ helicase has a unique set of protein-interacting partners, and these interactions dictate its specialized functions in genome maintenance, including DNA repair, recombination, replication, and transcription. Human RecQ helicases also interact with each other, and these interactions have significant impact on enzyme function. Future research goals in this field include a better understanding of the division of labor among the human RecQ helicases and learning how human RecQ helicases collaborate and cooperate to enhance genome stability.
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Affiliation(s)
- Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, Maryland 21224;
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Morrish TA, Bekbolysnov D, Velliquette D, Morgan M, Ross B, Wang Y, Chaney B, McQuigg J, Fager N, Maine IP. Multiple Mechanisms Contribute To Telomere Maintenance. JOURNAL OF CANCER BIOLOGY & RESEARCH 2013; 1:1012. [PMID: 25285314 PMCID: PMC4181876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The unlimited growth potential of tumors depends on telomere maintenance and typically depends on telomerase, an RNA-dependent DNA polymerase, which reverse transcribes the telomerase RNA template, synthesizing telomere repeats at the ends of chromosomes. Studies in various model organisms genetically deleted for telomerase indicate that several recombination-based mechanisms also contribute to telomere maintenance. Understanding the molecular basis of these mechanisms is critical since some human tumors form without telomerase, yet the sequence is maintained at the telomeres. Recombination-based mechanisms also likely contribute at some frequency to telomere maintenance in tumors expressing telomerase. Preventing telomere maintenance is predicted to impact tumor growth, yet inhibiting telomerase may select for the recombination-based mechanisms. Telomere recombination mechanisms likely involve altered or unregulated pathways of DNA repair. The use of some DNA damaging agents may encourage the use of these unregulated pathways of DNA repair to be utilized and may allow some tumors to generate resistance to these agents depending on which repair pathways are altered in the tumors. This review will discuss the various telomere recombination mechanisms and will provide rationale regarding the possibility that L1 retrotransposition may contribute to telomere maintenance in tumors lacking telomerase.
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Affiliation(s)
- Tammy A. Morrish
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Dulat Bekbolysnov
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
- Graduate Program in Microbiology and Immunology, University of Toledo, Toledo, OH 43614 USA
| | - David Velliquette
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Michelle Morgan
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Bryan Ross
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Yongheng Wang
- Department of Biological Sciences, University of Toledo, OH 43614, USA
| | - Benjamin Chaney
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Jessica McQuigg
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Nathan Fager
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
| | - Ira P. Maine
- Department of Biochemistry and Cancer Biology, University of Toledo, Toledo, OH 43614, USA
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