1
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Ramirez-Otero MA, Costanzo V. "Bridging the DNA divide": Understanding the interplay between replication- gaps and homologous recombination proteins RAD51 and BRCA1/2. DNA Repair (Amst) 2024; 141:103738. [PMID: 39084178 DOI: 10.1016/j.dnarep.2024.103738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/24/2024] [Accepted: 07/25/2024] [Indexed: 08/02/2024]
Abstract
A key but often neglected component of genomic instability is the emergence of single-stranded DNA (ssDNA) gaps during DNA replication in the absence of functional homologous recombination (HR) proteins, such as RAD51 and BRCA1/2. Research in prokaryotes has shed light on the dual role of RAD51's bacterial ortholog, RecA, in HR and the protection of replication forks, emphasizing its essential role in preventing the formation of ssDNA gaps, which is vital for cellular viability. This phenomenon was corroborated in eukaryotic cells deficient in HR, where the formation of ssDNA gaps within newly synthesized DNA and their subsequent processing by the MRE11 nuclease were observed. Without functional HR proteins, cells employ alternative ssDNA gap-filling mechanisms to ensure survival, though this compensatory response can compromise genomic stability. A notable example is the involvement of the translesion synthesis (TLS) polymerase POLζ, along with the repair protein POLθ, in the suppression of replicative ssDNA gaps. Persistent ssDNA gaps may result in replication fork collapse, chromosomal anomalies, and cell death, which contribute to cancer progression and resistance to therapy. Elucidating the processes that avert ssDNA gaps and safeguard replication forks is critical for enhancing cancer treatment approaches by exploiting the vulnerabilities of cancer cells in these pathways.
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Affiliation(s)
| | - Vincenzo Costanzo
- IFOM ETS - The AIRC Institute of Molecular Oncology, Italy; Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy.
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2
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Técher H. T-Rex escaped from the cytosolic park: Re-thinking the impact of TREX1 exonuclease deficiencies on genomic stability. Bioessays 2024; 46:e2400066. [PMID: 38837436 DOI: 10.1002/bies.202400066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/25/2024] [Accepted: 05/27/2024] [Indexed: 06/07/2024]
Abstract
The Three Prime Repair Exonuclease 1 (TREX1) has been implicated in several pathologies characterized by chronic and inborn inflammation. Aberrant innate immunity caused by DNA sensing through the cGAS-STING pathway has been proposed to play a major role in the etiology of these interferonopathies. However, the molecular source of this DNA sensing and the possible involvement of TREX1 in genome (in)stability remains poorly understood. Recent findings reignite the debate about the cellular functions performed by TREX1 nuclease, notably in chromosome biology and stability. Here I put into perspective recent findings that suggest that TREX1 is at the crossroads of DNA damage response and inflammation in different pathological contexts.
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Affiliation(s)
- Hervé Técher
- Université Côte d'Azur, CNRS, INSERM, Institute for Research on Cancer and Aging of Nice - IRCAN, Nice, France
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3
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Wen C, Cao L, Wang S, Xu W, Yu Y, Zhao S, Yang F, Chen ZJ, Zhao S, Yang Y, Qin Y. MCM8 interacts with DDX5 to promote R-loop resolution. EMBO J 2024; 43:3044-3071. [PMID: 38858601 PMCID: PMC11251167 DOI: 10.1038/s44318-024-00134-0] [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: 08/12/2023] [Revised: 05/17/2024] [Accepted: 05/21/2024] [Indexed: 06/12/2024] Open
Abstract
MCM8 has emerged as a core gene in reproductive aging and is crucial for meiotic homologous recombination repair. It also safeguards genome stability by coordinating the replication stress response during mitosis, but its function in mitotic germ cells remains elusive. Here we found that disabling MCM8 in mice resulted in proliferation defects of primordial germ cells (PGCs) and ultimately impaired fertility. We further demonstrated that MCM8 interacted with two known helicases DDX5 and DHX9, and loss of MCM8 led to R-loop accumulation by reducing the retention of these helicases at R-loops, thus inducing genome instability. Cells expressing premature ovarian insufficiency-causative mutants of MCM8 with decreased interaction with DDX5 displayed increased R-loop levels. These results show MCM8 interacts with R-loop-resolving factors to prevent R-loop-induced DNA damage, which may contribute to the maintenance of genome integrity of PGCs and reproductive reserve establishment. Our findings thus reveal an essential role for MCM8 in PGC development and improve our understanding of reproductive aging caused by genome instability in mitotic germ cells.
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Affiliation(s)
- Canxin Wen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Lili Cao
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Shuhan Wang
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Weiwei Xu
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Yongze Yu
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Simin Zhao
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Fan Yang
- Advanced Medical Research Institute, Meili Lake Translational Research Park, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, 250012, China
| | - Zi-Jiang Chen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
- Department of Reproductive Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shidou Zhao
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China.
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China.
| | - Yajuan Yang
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China.
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China.
| | - Yingying Qin
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China.
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China.
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4
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Goehring L, Keegan S, Lahiri S, Xia W, Kong M, Jimenez-Sainz J, Gupta D, Drapkin R, Jensen RB, Smith DJ, Rothenberg E, Fenyö D, Huang TT. Dormant origin firing promotes head-on transcription-replication conflicts at transcription termination sites in response to BRCA2 deficiency. Nat Commun 2024; 15:4716. [PMID: 38830843 PMCID: PMC11148086 DOI: 10.1038/s41467-024-48286-1] [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: 08/19/2023] [Accepted: 04/24/2024] [Indexed: 06/05/2024] Open
Abstract
BRCA2 is a tumor suppressor protein responsible for safeguarding the cellular genome from replication stress and genotoxicity, but the specific mechanism(s) by which this is achieved to prevent early oncogenesis remains unclear. Here, we provide evidence that BRCA2 acts as a critical suppressor of head-on transcription-replication conflicts (HO-TRCs). Using Okazaki-fragment sequencing (Ok-seq) and computational analysis, we identified origins (dormant origins) that are activated near the transcription termination sites (TTS) of highly expressed, long genes in response to replication stress. Dormant origins are a source for HO-TRCs, and drug treatments that inhibit dormant origin firing led to a reduction in HO-TRCs, R-loop formation, and DNA damage. Using super-resolution microscopy, we showed that HO-TRC events track with elongating RNA polymerase II, but not with transcription initiation. Importantly, RNase H2 is recruited to sites of HO-TRCs in a BRCA2-dependent manner to help alleviate toxic R-loops associated with HO-TRCs. Collectively, our results provide a mechanistic basis for how BRCA2 shields against genomic instability by preventing HO-TRCs through both direct and indirect means occurring at predetermined genomic sites based on the pre-cancer transcriptome.
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Affiliation(s)
- Liana Goehring
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Sarah Keegan
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Institute for Systems Genetics, New York University School of Medicine, New York University School of Medicine, New York, NY, USA
| | - Sudipta Lahiri
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Wenxin Xia
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Michael Kong
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | | | - Dipika Gupta
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Ronny Drapkin
- Penn Ovarian Cancer Research Center, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
- Basser Center for BRCA, Abramson Cancer Center, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Duncan J Smith
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Eli Rothenberg
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - David Fenyö
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Institute for Systems Genetics, New York University School of Medicine, New York University School of Medicine, New York, NY, USA
| | - Tony T Huang
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
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5
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Heuzé J, Kemiha S, Barthe A, Vilarrubias AT, Aouadi E, Aiello U, Libri D, Lin Y, Lengronne A, Poli J, Pasero P. RNase H2 degrades toxic RNA:DNA hybrids behind stalled forks to promote replication restart. EMBO J 2023; 42:e113104. [PMID: 37855233 PMCID: PMC10690446 DOI: 10.15252/embj.2022113104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 09/27/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023] Open
Abstract
R-loops represent a major source of replication stress, but the mechanism by which these structures impede fork progression remains unclear. To address this question, we monitored fork progression, arrest, and restart in Saccharomyces cerevisiae cells lacking RNase H1 and H2, two enzymes responsible for degrading RNA:DNA hybrids. We found that while RNase H-deficient cells could replicate their chromosomes normally under unchallenged growth conditions, their replication was impaired when exposed to hydroxyurea (HU) or methyl methanesulfonate (MMS). Treated cells exhibited increased levels of RNA:DNA hybrids at stalled forks and were unable to generate RPA-coated single-stranded (ssDNA), an important postreplicative intermediate in resuming replication. Similar impairments in nascent DNA resection and ssDNA formation at HU-arrested forks were observed in human cells lacking RNase H2. However, fork resection was fully restored by addition of triptolide, an inhibitor of transcription that induces RNA polymerase degradation. Taken together, these data indicate that RNA:DNA hybrids not only act as barriers to replication forks, but also interfere with postreplicative fork repair mechanisms if not promptly degraded by RNase H.
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Affiliation(s)
- Jonathan Heuzé
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Samira Kemiha
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Antoine Barthe
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Alba Torán Vilarrubias
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Elyès Aouadi
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Umberto Aiello
- Université Paris Cité, CNRS, Institut Jacques MonodParisFrance
- Department of GeneticsStanford UniversityStanfordCAUSA
| | - Domenico Libri
- Université Paris Cité, CNRS, Institut Jacques MonodParisFrance
- Present address:
Institut de Génétique Moléculaire de MontpellierUniversité de Montpellier, CNRSMontpellierFrance
| | - Yea‐Lih Lin
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Armelle Lengronne
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Jérôme Poli
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
- Institut Universitaire de France (IUF)ParisFrance
| | - Philippe Pasero
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
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6
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Thakur BL, Kusi NA, Mosavarpour S, Zhu R, Redon CE, Fu H, Dhall A, Pongor LS, Sebastian R, Indig FE, Aladjem MI. SIRT1 Prevents R-Loops during Chronological Aging by Modulating DNA Replication at rDNA Loci. Cells 2023; 12:2630. [PMID: 37998365 PMCID: PMC10669956 DOI: 10.3390/cells12222630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/25/2023] Open
Abstract
In metazoans, the largest sirtuin, SIRT1, is a nuclear protein implicated in epigenetic modifications, circadian signaling, DNA recombination, replication, and repair. Our previous studies have demonstrated that SIRT1 binds replication origins and inhibits replication initiation from a group of potential initiation sites (dormant origins). We studied the effects of aging and SIRT1 activity on replication origin usage and the incidence of transcription-replication collisions (creating R-loop structures) in adult human cells obtained at different time points during chronological aging and in cancer cells. In primary, untransformed cells, SIRT1 activity declined and the prevalence of R-loops rose with chronological aging. Both the reduction in SIRT1 activity and the increased abundance of R-loops were also observed during the passage of primary cells in culture. All cells, regardless of donor age or transformation status, reacted to the short-term, acute chemical inhibition of SIRT1 with the activation of excessive replication initiation events coincident with an increased prevalence of R-loops. However, cancer cells activated dormant replication origins, genome-wide, during long-term proliferation with mutated or depleted SIRT1, whereas, in primary cells, the aging-associated SIRT1-mediated activation of dormant origins was restricted to rDNA loci. These observations suggest that chronological aging and the associated decline in SIRT1 activity relax the regulatory networks that protect cells against excess replication and that the mechanisms protecting from replication-transcription collisions at the rDNA loci manifest as differentially enhanced sensitivities to SIRT1 decline and chronological aging.
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Affiliation(s)
- Bhushan L. Thakur
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Nana A. Kusi
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Sara Mosavarpour
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Roger Zhu
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Christophe E. Redon
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Haiqing Fu
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Anjali Dhall
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Lorinc S. Pongor
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Robin Sebastian
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
| | - Fred E. Indig
- Confocal Imaging Facility, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA;
| | - Mirit I. Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (B.L.T.); (N.A.K.); (S.M.); (R.Z.); (C.E.R.); (H.F.); (A.D.); (L.S.P.); (R.S.)
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7
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Gambelli A, Ferrando A, Boncristiani C, Schoeftner S. Regulation and function of R-loops at repetitive elements. Biochimie 2023; 214:141-155. [PMID: 37619810 DOI: 10.1016/j.biochi.2023.08.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/13/2023] [Accepted: 08/19/2023] [Indexed: 08/26/2023]
Abstract
R-loops are atypical, three-stranded nucleic acid structures that contain a stretch of RNA:DNA hybrids and an unpaired, single stranded DNA loop. R-loops are physiological relevant and can act as regulators of gene expression, chromatin structure, DNA damage repair and DNA replication. However, unscheduled and persistent R-loops are mutagenic and can mediate replication-transcription conflicts, leading to DNA damage and genome instability if left unchecked. Detailed transcriptome analysis unveiled that 85% of the human genome, including repetitive regions, hold transcriptional activity. This anticipates that R-loops management plays a central role for the regulation and integrity of genomes. This function is expected to have a particular relevance for repetitive sequences that make up to 75% of the human genome. Here, we review the impact of R-loops on the function and stability of repetitive regions such as centromeres, telomeres, rDNA arrays, transposable elements and triplet repeat expansions and discuss their relevance for associated pathological conditions.
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Affiliation(s)
- Alice Gambelli
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Alessandro Ferrando
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Chiara Boncristiani
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Stefan Schoeftner
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.
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8
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Heuzé J, Lin YL, Lengronne A, Poli J, Pasero P. Impact of R-loops on oncogene-induced replication stress in cancer cells. C R Biol 2023; 346:95-105. [PMID: 37779381 DOI: 10.5802/crbiol.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 10/03/2023]
Abstract
Replication stress is an alteration in the progression of replication forks caused by a variety of events of endogenous or exogenous origin. In precancerous lesions, this stress is exacerbated by the deregulation of oncogenic pathways, which notably disrupts the coordination between replication and transcription, and leads to genetic instability and cancer development. It is now well established that transcription can interfere with genome replication in different ways, such as head-on collisions between polymerases, accumulation of positive DNA supercoils or formation of R-loops. These structures form during transcription when nascent RNA reanneals with DNA behind the RNA polymerase, forming a stable DNA:RNA hybrid. In this review, we discuss how these different cotranscriptional processes disrupt the progression of replication forks and how they contribute to genetic instability in cancer cells.
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9
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Miller CLW, Winston F. The conserved histone chaperone Spt6 is strongly required for DNA replication and genome stability. Cell Rep 2023; 42:112264. [PMID: 36924499 PMCID: PMC10106089 DOI: 10.1016/j.celrep.2023.112264] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 12/31/2022] [Accepted: 02/27/2023] [Indexed: 03/17/2023] Open
Abstract
Histone chaperones are an important class of proteins that regulate chromatin accessibility for DNA-templated processes. Spt6 is a conserved histone chaperone and key regulator of transcription and chromatin structure. However, its functions outside of these roles have been little explored. In this work, we demonstrate a requirement for S. cerevisiae Spt6 in DNA replication and, more broadly, as a regulator of genome stability. Depletion or mutation of Spt6 impairs DNA replication in vivo. Additionally, spt6 mutants are sensitive to DNA replication stress-inducing agents. Interestingly, this sensitivity is independent of the association of Spt6 with RNA polymerase II (RNAPII), suggesting that spt6 mutants have a transcription-independent impairment of DNA replication. Specifically, genomic studies reveal that spt6 mutants have decreased loading of the MCM replicative helicase at replication origins, suggesting that Spt6 promotes origin licensing. Our results identify Spt6 as a regulator of genome stability, at least in part through a role in DNA replication.
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Affiliation(s)
- Catherine L W Miller
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Fred Winston
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
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10
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RNA:DNA hybrids from Okazaki fragments contribute to establish the Ku-mediated barrier to replication-fork degradation. Mol Cell 2023; 83:1061-1074.e6. [PMID: 36868227 DOI: 10.1016/j.molcel.2023.02.008] [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: 12/14/2021] [Revised: 12/09/2022] [Accepted: 02/04/2023] [Indexed: 03/05/2023]
Abstract
Nonhomologous end-joining (NHEJ) factors act in replication-fork protection, restart, and repair. Here, we identified a mechanism related to RNA:DNA hybrids to establish the NHEJ factor Ku-mediated barrier to nascent strand degradation in fission yeast. RNase H activities promote nascent strand degradation and replication restart, with a prominent role of RNase H2 in processing RNA:DNA hybrids to overcome the Ku barrier to nascent strand degradation. RNase H2 cooperates with the MRN-Ctp1 axis to sustain cell resistance to replication stress in a Ku-dependent manner. Mechanistically, the need of RNaseH2 in nascent strand degradation requires the primase activity that allows establishing the Ku barrier to Exo1, whereas impairing Okazaki fragment maturation reinforces the Ku barrier. Finally, replication stress induces Ku foci in a primase-dependent manner and favors Ku binding to RNA:DNA hybrids. We propose a function for the RNA:DNA hybrid originating from Okazaki fragments in controlling the Ku barrier specifying nuclease requirement to engage fork resection.
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11
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Boddu PC, Gupta A, Roy R, De La Pena Avalos B, Herrero AO, Neuenkirchen N, Zimmer J, Chandhok N, King D, Nannya Y, Ogawa S, Lin H, Simon M, Dray E, Kupfer G, Verma AK, Neugebauer KM, Pillai MM. Transcription elongation defects link oncogenic splicing factor mutations to targetable alterations in chromatin landscape. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.25.530019. [PMID: 36891287 PMCID: PMC9994134 DOI: 10.1101/2023.02.25.530019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Transcription and splicing of pre-messenger RNA are closely coordinated, but how this functional coupling is disrupted in human disease remains unexplored. Here, we investigated the impact of non-synonymous mutations in SF3B1 and U2AF1, two commonly mutated splicing factors in cancer, on transcription. We find that the mutations impair RNA Polymerase II (RNAPII) transcription elongation along gene bodies leading to transcription-replication conflicts, replication stress and altered chromatin organization. This elongation defect is linked to disrupted pre-spliceosome assembly due to impaired association of HTATSF1 with mutant SF3B1. Through an unbiased screen, we identified epigenetic factors in the Sin3/HDAC complex, which, when modulated, normalize transcription defects and their downstream effects. Our findings shed light on the mechanisms by which oncogenic mutant spliceosomes impact chromatin organization through their effects on RNAPII transcription elongation and present a rationale for targeting the Sin3/HDAC complex as a potential therapeutic strategy. GRAPHICAL ABSTRACT HIGHLIGHTS Oncogenic mutations of SF3B1 and U2AF1 cause a gene-body RNAPII elongation defectRNAPII transcription elongation defect leads to transcription replication conflicts, DNA damage response, and changes to chromatin organization and H3K4me3 marksThe transcription elongation defect is linked to disruption of the early spliceosome formation through impaired interaction of HTATSF1 with mutant SF3B1.Changes to chromatin organization reveal potential therapeutic strategies by targeting the Sin3/HDAC pathway.
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12
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Brown RE, Su XA, Fair S, Wu K, Verra L, Jong R, Andrykovich K, Freudenreich CH. The RNA export and RNA decay complexes THO and TRAMP prevent transcription-replication conflicts, DNA breaks, and CAG repeat contractions. PLoS Biol 2022; 20:e3001940. [PMID: 36574440 PMCID: PMC9829180 DOI: 10.1371/journal.pbio.3001940] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/09/2023] [Accepted: 12/01/2022] [Indexed: 12/28/2022] Open
Abstract
Expansion of structure-forming CAG/CTG repetitive sequences is the cause of several neurodegenerative disorders and deletion of repeats is a potential therapeutic strategy. Transcription-associated mechanisms are known to cause CAG repeat instability. In this study, we discovered that Thp2, an RNA export factor and member of the THO (suppressors of transcriptional defects of hpr1Δ by overexpression) complex, and Trf4, a key component of the TRAMP (Trf4/5-Air1/2-Mtr4 polyadenylation) complex involved in nuclear RNA polyadenylation and degradation, are necessary to prevent CAG fragility and repeat contractions in a Saccharomyces cerevisiae model system. Depletion of both Thp2 and Trf4 proteins causes a highly synergistic increase in CAG repeat fragility, indicating a complementary role of the THO and TRAMP complexes in preventing genome instability. Loss of either Thp2 or Trf4 causes an increase in RNA polymerase stalling at the CAG repeats and other genomic loci, as well as genome-wide transcription-replication conflicts (TRCs), implicating TRCs as a cause of CAG fragility and instability in their absence. Analysis of the effect of RNase H1 overexpression on CAG fragility, RNAPII stalling, and TRCs suggests that RNAPII stalling with associated R-loops are the main cause of CAG fragility in the thp2Δ mutants. In contrast, CAG fragility and TRCs in the trf4Δ mutant can be compensated for by RPA overexpression, suggesting that excess unprocessed RNA in TRAMP4 mutants leads to reduced RPA availability and high levels of TRCs. Our results show the importance of RNA surveillance pathways in preventing RNAPII stalling, TRCs, and DNA breaks, and show that RNA export and RNA decay factors work collaboratively to maintain genome stability.
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Affiliation(s)
- Rebecca E. Brown
- Program in Genetics, Tufts University School of Graduate Biomedical Sciences, Boston, Massachusetts, United States of America
| | - Xiaofeng A. Su
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
- David H. Koch Institute for Integrative Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Stacey Fair
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Katherine Wu
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Lauren Verra
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Robyn Jong
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Kristin Andrykovich
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Catherine H. Freudenreich
- Program in Genetics, Tufts University School of Graduate Biomedical Sciences, Boston, Massachusetts, United States of America
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
- * E-mail:
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13
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Said M, Barra V, Balzano E, Talhaoui I, Pelliccia F, Giunta S, Naim V. FANCD2 promotes mitotic rescue from transcription-mediated replication stress in SETX-deficient cancer cells. Commun Biol 2022; 5:1395. [PMID: 36543851 PMCID: PMC9772326 DOI: 10.1038/s42003-022-04360-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Replication stress (RS) is a leading cause of genome instability and cancer development. A substantial source of endogenous RS originates from the encounter between the transcription and replication machineries operating on the same DNA template. This occurs predominantly under specific contexts, such as oncogene activation, metabolic stress, or a deficiency in proteins that specifically act to prevent or resolve those transcription-replication conflicts (TRCs). One such protein is Senataxin (SETX), an RNA:DNA helicase involved in resolution of TRCs and R-loops. Here we identify a synthetic lethal interaction between SETX and proteins of the Fanconi anemia (FA) pathway. Depletion of SETX induces spontaneous under-replication and chromosome fragility due to active transcription and R-loops that persist in mitosis. These fragile loci are targeted by the Fanconi anemia protein, FANCD2, to facilitate the resolution of under-replicated DNA, thus preventing chromosome mis-segregation and allowing cells to proliferate. Mechanistically, we show that FANCD2 promotes mitotic DNA synthesis that is dependent on XPF and MUS81 endonucleases. Importantly, co-depleting FANCD2 together with SETX impairs cancer cell proliferation, without significantly affecting non-cancerous cells. Therefore, we uncovered a synthetic lethality between SETX and FA proteins for tolerance of transcription-mediated RS that may be exploited for cancer therapy.
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Affiliation(s)
- Maha Said
- grid.14925.3b0000 0001 2284 9388CNRS UMR9019, Université Paris-Saclay, Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Viviana Barra
- grid.10776.370000 0004 1762 5517Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Elisa Balzano
- grid.7841.aDepartment of Biology & Biotechnology “Charles Darwin”, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Ibtissam Talhaoui
- grid.14925.3b0000 0001 2284 9388CNRS UMR9019, Université Paris-Saclay, Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Franca Pelliccia
- grid.7841.aDepartment of Biology & Biotechnology “Charles Darwin”, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Simona Giunta
- grid.7841.aDepartment of Biology & Biotechnology “Charles Darwin”, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Valeria Naim
- grid.14925.3b0000 0001 2284 9388CNRS UMR9019, Université Paris-Saclay, Gustave Roussy, 114 rue Edouard Vaillant, 94805 Villejuif, France
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14
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Bhowmick R, Lerdrup M, Gadi SA, Rossetti GG, Singh MI, Liu Y, Halazonetis TD, Hickson ID. RAD51 protects human cells from transcription-replication conflicts. Mol Cell 2022; 82:3366-3381.e9. [PMID: 36002000 DOI: 10.1016/j.molcel.2022.07.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 06/02/2022] [Accepted: 07/16/2022] [Indexed: 12/16/2022]
Abstract
Oncogene activation during tumorigenesis promotes DNA replication stress (RS), which subsequently drives the formation of cancer-associated chromosomal rearrangements. Many episodes of physiological RS likely arise due to conflicts between the DNA replication and transcription machineries operating simultaneously at the same loci. One role of the RAD51 recombinase in human cells is to protect replication forks undergoing RS. Here, we have identified a key role for RAD51 in preventing transcription-replication conflicts (TRCs) from triggering replication fork breakage. The genomic regions most affected by RAD51 deficiency are characterized by being replicated and transcribed in early S-phase and show significant overlap with loci prone to cancer-associated amplification. Consistent with a role for RAD51 in protecting against transcription-replication conflicts, many of the adverse effects of RAD51 depletion are ameliorated by inhibiting early S-phase transcription. We propose a model whereby RAD51 suppresses fork breakage and subsequent inadvertent amplification of genomic loci prone to experiencing TRCs.
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Affiliation(s)
- Rahul Bhowmick
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Mads Lerdrup
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Sampath Amitash Gadi
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Giacomo G Rossetti
- Department of Molecular Biology, University of Geneva, 30, quai Ernest-Ansermet, 1205, Geneva, Switzerland
| | - Manika I Singh
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Ying Liu
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Thanos D Halazonetis
- Department of Molecular Biology, University of Geneva, 30, quai Ernest-Ansermet, 1205, Geneva, Switzerland
| | - Ian D Hickson
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark.
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15
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Shaw AE, Kairamkonda S, Ghodke H, Schauer GD. Biochemical and single-molecule techniques to study accessory helicase resolution of R-loop proteins at stalled replication forks. Methods Enzymol 2022; 673:191-225. [PMID: 35965008 DOI: 10.1016/bs.mie.2022.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
R-loop proteins present a stable and robust blockade to the progression of a DNA replication fork during S-phase. The consequences of this block can include mutagenesis and other irreversible chromosomal catastrophes, causing genomic instability and disease. As such, further investigation into the molecular mechanisms underlying R-loop protein resolution is warranted. The critical role of non-replicative accessory helicases in R-loop protein resolution has increasingly come into light in recent years. Such helicases include the Pif1-family, monomeric helicases that have been studied in many different contexts and that have been ascribed to a multitude of separable protective functions in the cell. In this chapter, we present protocols to study R-loop protein resolution by Pif1 helicase at stalled replication forks using purified proteins, both at the biochemical and single-molecule level. Our system uses recombinant proteins expressed in Saccharomyces cerevisiae but could apply to practically any organism of interest due to the high interspecies homology of the proteins involved in DNA replication. The methods we outline are extensible to many systems and should be applicable to studying R-loop clearance by any Superfamily (SF) 1B helicase. These techniques will further enable mechanistic research on these critical but understudied components of the genomic maintenance program.
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Affiliation(s)
- Alisa E Shaw
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
| | - Sreeya Kairamkonda
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
| | - Harshad Ghodke
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia; Illawarra Health & Medical Research Institute, Wollongong, NSW, Australia
| | - Grant D Schauer
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States.
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16
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Chen J, Li S, Chen Y, Yang J, Dong J. Highly selective detection of adenine and guanine by NH 2-MIL-53(Fe)/CS/MXene nanocomposites with excellent electrochemical performance. Mikrochim Acta 2022; 189:328. [PMID: 35962293 DOI: 10.1007/s00604-022-05376-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/17/2022] [Indexed: 11/28/2022]
Abstract
Adenine (A) and guanine (G) are mainly found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) and play a crucial role in genetic information transfer and protein synthesis. In this study, NH2-MIL-53(Fe)/CS/MXene nanocomposites were prepared for detecting guanine and adenine. With high specific surface area, excellent water dispersion, and numerous active sites, MXene (transition metal carbides, nitrides, and carbonitrides) provides a good platform for loading primitive metal-organic frameworks (MOFs). At the same time, the problem of poor conductivity and dispersion of MOFs is solved. The electrochemical catalytic oxidation of adenine and guanine of NH2-MIL-53 (Fe)/CS/MXene nanocomposites was carried out by differential pulse voltammetry (DPV). Operating voltage of DPV: 0.7-0.9 V (vs. Ag/AgCl) for G, 1.0-1.2 V (vs. Ag/AgCl) for A, 0.8 V (vs. Ag/AgCl), and 1.1 V (vs. Ag/AgCl) for G and A. The concentration ranges for detecting A and G were 3-118 μM and 2-120 μM with detection limits of 0.57 μM and 0.17 μM (S/N = 3), respectively. The nanocomposite was used for detecting G and A in herring sperm DNA, and the content of G and A was found to be about 9 and 11 μM; the RSD values were 3.4 and 1.3%, respectively.
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Affiliation(s)
- Jing Chen
- Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, People's Republic of China.
| | - Shuying Li
- Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, People's Republic of China
| | | | - Jiao Yang
- Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, People's Republic of China
| | - Jianbin Dong
- Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, People's Republic of China
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17
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Brickner JR, Garzon JL, Cimprich KA. Walking a tightrope: The complex balancing act of R-loops in genome stability. Mol Cell 2022; 82:2267-2297. [PMID: 35508167 DOI: 10.1016/j.molcel.2022.04.014] [Citation(s) in RCA: 96] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/28/2022] [Accepted: 04/10/2022] [Indexed: 12/14/2022]
Abstract
Although transcription is an essential cellular process, it is paradoxically also a well-recognized cause of genomic instability. R-loops, non-B DNA structures formed when nascent RNA hybridizes to DNA to displace the non-template strand as single-stranded DNA (ssDNA), are partially responsible for this instability. Yet, recent work has begun to elucidate regulatory roles for R-loops in maintaining the genome. In this review, we discuss the cellular contexts in which R-loops contribute to genomic instability, particularly during DNA replication and double-strand break (DSB) repair. We also summarize the evidence that R-loops participate as an intermediate during repair and may influence pathway choice to preserve genomic integrity. Finally, we discuss the immunogenic potential of R-loops and highlight their links to disease should they become pathogenic.
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Affiliation(s)
- Joshua R Brickner
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jada L Garzon
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Karlene A Cimprich
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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