1
|
Olson CL, Wuttke DS. Guardians of the Genome: How the Single-Stranded DNA-Binding Proteins RPA and CST Facilitate Telomere Replication. Biomolecules 2024; 14:263. [PMID: 38540683 PMCID: PMC10968030 DOI: 10.3390/biom14030263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/02/2024] [Accepted: 02/20/2024] [Indexed: 04/26/2024] Open
Abstract
Telomeres act as the protective caps of eukaryotic linear chromosomes; thus, proper telomere maintenance is crucial for genome stability. Successful telomere replication is a cornerstone of telomere length regulation, but this process can be fraught due to the many intrinsic challenges telomeres pose to the replication machinery. In addition to the famous "end replication" problem due to the discontinuous nature of lagging strand synthesis, telomeres require various telomere-specific steps for maintaining the proper 3' overhang length. Bulk telomere replication also encounters its own difficulties as telomeres are prone to various forms of replication roadblocks. These roadblocks can result in an increase in replication stress that can cause replication forks to slow, stall, or become reversed. Ultimately, this leads to excess single-stranded DNA (ssDNA) that needs to be managed and protected for replication to continue and to prevent DNA damage and genome instability. RPA and CST are single-stranded DNA-binding protein complexes that play key roles in performing this task and help stabilize stalled forks for continued replication. The interplay between RPA and CST, their functions at telomeres during replication, and their specialized features for helping overcome replication stress at telomeres are the focus of this review.
Collapse
Affiliation(s)
- Conner L. Olson
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S. Wuttke
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| |
Collapse
|
2
|
Lim YS, Nguyen MT, Pham TX, Huynh TT, Park EM, Choi DH, Kang SM, Tark D, Hwang SB. Hepatitis C Virus Nonstructural 5A Protein Interacts with Telomere Length Regulation Protein: Implications for Telomere Shortening in Patients Infected with HCV. Mol Cells 2022; 45:148-157. [PMID: 34949741 PMCID: PMC8926864 DOI: 10.14348/molcells.2021.0167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/17/2021] [Accepted: 10/27/2021] [Indexed: 11/27/2022] Open
Abstract
Hepatitis C virus (HCV) is a major cause of chronic liver disease and is highly dependent on cellular proteins for viral propagation. Using protein microarray analysis, we identified 90 cellular proteins as HCV nonstructural 5A (NS5A) interacting partners, and selected telomere length regulation protein (TEN1) for further study. TEN1 forms a heterotrimeric complex with CTC and STN1, which is essential for telomere protection and maintenance. Telomere length decreases in patients with active HCV, chronic liver disease, and hepatocellular carcinoma. However, the molecular mechanism of telomere length shortening in HCV-associated disease is largely unknown. In the present study, protein interactions between NS5A and TEN1 were confirmed by immunoprecipitation assays. Silencing of TEN1 reduced both viral RNA and protein expression levels of HCV, while ectopic expression of the siRNA-resistant TEN1 recovered the viral protein level, suggesting that TEN1 was specifically required for HCV propagation. Importantly, we found that TEN1 is re-localized from the nucleus to the cytoplasm in HCV-infected cells. These data suggest that HCV exploits TEN1 to promote viral propagation and that telomere protection is compromised in HCV-infected cells. Overall, our findings provide mechanistic insight into the telomere shortening in HCV-infected cells.
Collapse
Affiliation(s)
- Yun-Sook Lim
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
| | - Men T.N. Nguyen
- Ilsong Institute of Life Science, Hallym University, Seoul 07247, Korea
| | - Thuy X. Pham
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
| | - Trang T.X. Huynh
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
| | - Eun-Mee Park
- Center for Immunology and Pathology, National Institute of Health, Korea Center for Disease Control & Prevention, Cheongju 28159, Korea
| | - Dong Hwa Choi
- Biocenter, Gyeonggido Business & Science Accelerator, Suwon 16229, Korea
| | - Sang Min Kang
- Laboratory for Infectious Disease Prevention, Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
| | - Dongseob Tark
- Laboratory for Infectious Disease Prevention, Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
| | - Soon B. Hwang
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Jeonbuk National University, Iksan 54531, Korea
- Ilsong Institute of Life Science, Hallym University, Seoul 07247, Korea
| |
Collapse
|
3
|
Schuck PL, Ball LE, Stewart JA. The DNA-binding protein CST associates with the cohesin complex and promotes chromosome cohesion. J Biol Chem 2021; 297:101026. [PMID: 34339741 PMCID: PMC8390553 DOI: 10.1016/j.jbc.2021.101026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/22/2021] [Accepted: 07/29/2021] [Indexed: 01/26/2023] Open
Abstract
Sister chromatid cohesion (SCC), the pairing of sister chromatids after DNA replication until mitosis, is established by loading of the cohesin complex on newly replicated chromatids. Cohesin must then be maintained until mitosis to prevent segregation defects and aneuploidy. However, how SCC is established and maintained until mitosis remains incompletely understood, and emerging evidence suggests that replication stress may lead to premature SCC loss. Here, we report that the ssDNA-binding protein CTC1-STN1-TEN1 (CST) aids in SCC. CST primarily functions in telomere length regulation but also has known roles in replication restart and DNA repair. After depletion of CST subunits, we observed an increase in the complete loss of SCC. In addition, we determined that CST associates with the cohesin complex. Unexpectedly, we did not find evidence of altered cohesin loading or mitotic progression in the absence of CST; however, we did find that treatment with various replication inhibitors increased the association between CST and cohesin. Because replication stress was recently shown to induce SCC loss, we hypothesized that CST may be required to maintain or remodel SCC after DNA replication fork stalling. In agreement with this idea, SCC loss was greatly increased in CST-depleted cells after exogenous replication stress. Based on our findings, we propose that CST aids in the maintenance of SCC at stalled replication forks to prevent premature cohesion loss.
Collapse
Affiliation(s)
- P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, USA
| | - Lauren E Ball
- Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, USA.
| |
Collapse
|
4
|
Barazas M, Annunziato S, Pettitt SJ, de Krijger I, Ghezraoui H, Roobol SJ, Lutz C, Frankum J, Song FF, Brough R, Evers B, Gogola E, Bhin J, van de Ven M, van Gent DC, Jacobs JJL, Chapman R, Lord CJ, Jonkers J, Rottenberg S. The CST Complex Mediates End Protection at Double-Strand Breaks and Promotes PARP Inhibitor Sensitivity in BRCA1-Deficient Cells. Cell Rep 2018; 23:2107-2118. [PMID: 29768208 PMCID: PMC5972230 DOI: 10.1016/j.celrep.2018.04.046] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/24/2018] [Accepted: 04/11/2018] [Indexed: 12/29/2022] Open
Abstract
Selective elimination of BRCA1-deficient cells by inhibitors of poly(ADP-ribose) polymerase (PARP) is a prime example of the concept of synthetic lethality in cancer therapy. This interaction is counteracted by the restoration of BRCA1-independent homologous recombination through loss of factors such as 53BP1, RIF1, and REV7/MAD2L2, which inhibit end resection of DNA double-strand breaks (DSBs). To identify additional factors involved in this process, we performed CRISPR/SpCas9-based loss-of-function screens and selected for factors that confer PARP inhibitor (PARPi) resistance in BRCA1-deficient cells. Loss of members of the CTC1-STN1-TEN1 (CST) complex were found to cause PARPi resistance in BRCA1-deficient cells in vitro and in vivo. We show that CTC1 depletion results in the restoration of end resection and that the CST complex may act downstream of 53BP1/RIF1. These data suggest that, in addition to its role in protecting telomeres, the CST complex also contributes to protecting DSBs from end resection.
Collapse
Affiliation(s)
- Marco Barazas
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Stefano Annunziato
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Stephen J Pettitt
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Inge de Krijger
- Division of Oncogenomics, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Hind Ghezraoui
- Genome Integrity Laboratory, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Stefan J Roobol
- Department of Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Radiology and Nuclear Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Catrin Lutz
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Jessica Frankum
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Fei Fei Song
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Rachel Brough
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Bastiaan Evers
- Division of Molecular Carcinogenesis, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Ewa Gogola
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Jinhyuk Bhin
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Division of Molecular Carcinogenesis, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Marieke van de Ven
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Mouse Clinic for Cancer and Aging Research (MCCA), Preclinical Intervention Unit, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Dik C van Gent
- Department of Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jacqueline J L Jacobs
- Division of Oncogenomics, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Ross Chapman
- Genome Integrity Laboratory, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Christopher J Lord
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Jos Jonkers
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands.
| | - Sven Rottenberg
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
| |
Collapse
|
5
|
Abstract
Mammalian CST (CTC1-STN1-TEN1) is a telomere-associated complex that functions in telomere duplex replication and fill-in synthesis of the telomeric C-strand following telomerase action. CST also facilitates genome-wide replication recovery after HU-induced fork stalling by increasing origin firing. CTC1 and STN1 were originally isolated as a DNA polymerase α stimulatory factor. Here we explore how CST abundance affects recovery from drugs that cause different types of DNA damage and replication stress. We show that recovery from HU and aphidicolin induced replication stress is increased by CST over-expression. Elevated CST increases dNTP incorporation and origin firing after HU release and decreases the incidence of anaphase bridges and micronuclei after aphidicolin removal. While the frequency of origin firing after HU release is proportional to CST abundance, the number of cells entering S-phase to initiate replication is unchanged by CST overexpression or STN1 depletion. Instead the CST-related changes in origin firing take place in cells that were already in S-phase at the time of HU addition, indicating that CST modulates firing of late or dormant origins. CST abundance also influences cell viability after treatment with HU, aphidicolin, MMS and camptothecin. Viability is increased by elevated CST and decreased by STN1 depletion, indicating that endogenous CST levels are limiting. However, CST abundance does not affect viability after MMC treatment. Thus, CST facilitates recovery from many, but not all, forms of exogenous DNA damage. Overall our results suggest that CST is needed in stoichiometric amounts to facilitate re-initiation of DNA replication at repaired forks and/or dormant origins.
Collapse
Affiliation(s)
- Feng Wang
- a Department of Cancer Biology ; University of Cincinnati ; Cincinnati , OH USA
| | | | | |
Collapse
|
6
|
Gramatges MM, Bertuch AA. Short telomeres: from dyskeratosis congenita to sporadic aplastic anemia and malignancy. Transl Res 2013; 162:353-63. [PMID: 23732052 DOI: 10.1016/j.trsl.2013.05.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 05/06/2013] [Accepted: 05/09/2013] [Indexed: 12/20/2022]
Abstract
Telomeres are DNA-protein structures that form a protective cap on chromosome ends. As such, they prevent the natural ends of linear chromosomes from being subjected to DNA repair activities that would result in telomere fusion, degradation, or recombination. Both the DNA and protein components of the telomere are required for this essential function, because insufficient telomeric DNA length, loss of the terminal telomeric DNA structure, or deficiency of key telomere-associated factors may elicit a DNA damage response and result in cellular senescence or apoptosis. In the setting of failed checkpoint mechanisms, such DNA-protein defects can also lead to genomic instability through telomere fusions or recombination. Thus, as shown in both model systems and in humans, defects in telomere biology are implicated in cellular and organismal aging as well as in tumorigenesis. Bone marrow failure and malignancy are 2 life-threatening disease manifestations in the inherited telomere biology disorder dyskeratosis congenita. We provide an overview of basic telomere structure and maintenance. We outline the telomere biology defects observed in dyskeratosis congenita, focusing on recent discoveries in this field. Last, we review the evidence of how telomere biology may impact sporadic aplastic anemia and the risk for various cancers.
Collapse
|