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Impacts of chromatin dynamics and compartmentalization on DNA repair. DNA Repair (Amst) 2021; 105:103162. [PMID: 34182258 DOI: 10.1016/j.dnarep.2021.103162] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/10/2021] [Accepted: 06/17/2021] [Indexed: 11/22/2022]
Abstract
The proper spatial organization of DNA, RNA, and proteins is critical for a variety of cellular processes. The genome is organized into numerous functional units, such as topologically associating domains (TADs), the formation of which is regulated by both proteins and RNA. In addition, a group of chromatin-bound proteins with the ability to undergo liquid-liquid phase separation (LLPS) can affect the spatial organization and compartmentalization of chromatin, RNA, and proteins by forming condensates, conferring unique properties to specific chromosomal regions. Although the regulation of DNA repair by histone modifications and chromatin accessibility is well established, the impacts of higher-order chromatin and protein organization on the DNA damage response (DDR) have not been appreciated until recently. In this review, we will focus on the movement of chromatin during the DDR, the compartmentalization of DDR proteins via LLPS, and the roles of membraneless nuclear bodies and transcription in DNA repair. With this backdrop, we will discuss the importance of the spatial organization of chromatin and proteins for the maintenance of genome integrity.
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Velichko AK, Ovsyannikova N, Petrova NV, Luzhin AV, Vorobjeva M, Gavrikov AS, Mishin AS, Kireev II, Razin SV, Kantidze OL. Treacle and TOPBP1 control replication stress response in the nucleolus. J Cell Biol 2021; 220:212262. [PMID: 34100862 PMCID: PMC8190600 DOI: 10.1083/jcb.202008085] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 04/26/2021] [Accepted: 05/18/2021] [Indexed: 12/22/2022] Open
Abstract
Replication stress is one of the main sources of genome instability. Although the replication stress response in eukaryotic cells has been extensively studied, almost nothing is known about the replication stress response in nucleoli. Here, we demonstrate that initial replication stress-response factors, such as RPA, TOPBP1, and ATR, are recruited inside the nucleolus in response to drug-induced replication stress. The role of TOPBP1 goes beyond the typical replication stress response; it interacts with the low-complexity nucleolar protein Treacle (also referred to as TCOF1) and forms large Treacle-TOPBP1 foci inside the nucleolus. In response to replication stress, Treacle and TOPBP1 facilitate ATR signaling at stalled replication forks, reinforce ATR-mediated checkpoint activation inside the nucleolus, and promote the recruitment of downstream replication stress response proteins inside the nucleolus without forming nucleolar caps. Characterization of the Treacle-TOPBP1 interaction mode leads us to propose that these factors can form a molecular platform for efficient stress response in the nucleolus.
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Affiliation(s)
- Artem K Velichko
- Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia.,Institute for Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russia
| | - Natalia Ovsyannikova
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Artem V Luzhin
- Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
| | - Maria Vorobjeva
- Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
| | - Alexey S Gavrikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, Russia
| | - Alexander S Mishin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, Russia
| | - Igor I Kireev
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.,V.I. Kulakov National Medical Research Center for Obstetrics, Gynecology, and Perinatology, Moscow, Russia
| | - Sergey V Razin
- Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
| | - Omar L Kantidze
- Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
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Lesage E, Clouaire T, Legube G. Repair of DNA double-strand breaks in RNAPI- and RNAPII-transcribed loci. DNA Repair (Amst) 2021; 104:103139. [PMID: 34111758 DOI: 10.1016/j.dnarep.2021.103139] [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: 03/02/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 12/15/2022]
Abstract
DNA double-strand breaks (DSBs) are toxic lesions triggered not only by environmental sources, but also by a large number of physiological processes. Of importance, endogenous DSBs frequently occur in genomic loci that are transcriptionally active. Recent work suggests that DSBs occurring in transcribed loci are handled by specific pathway(s) that entail local transcriptional repression, chromatin signaling, the involvement of RNA species and DSB mobility. In this Graphical Review we provide an updated view of the "Transcription-Coupled DSB Repair" (TC-DSBR) pathway(s) that are mounted at DSBs occurring in loci transcribed by RNA Polymerase I (RNAPI) or RNA Polymerase II (RNAPII), highlighting differences and common features, as well as yet unanswered questions.
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Affiliation(s)
- E Lesage
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), UPS, CNRS, Toulouse, France
| | - T Clouaire
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), UPS, CNRS, Toulouse, France
| | - G Legube
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), UPS, CNRS, Toulouse, France.
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Abstract
Frattini et al. (2021) demonstrate that TopBP1 forms phase-separated nuclear condensates to promote activation of ATR in cells experiencing genomic stress.
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Thada V, Cortez D. ATR activation is regulated by dimerization of ATR activating proteins. J Biol Chem 2021; 296:100455. [PMID: 33636182 PMCID: PMC7994790 DOI: 10.1016/j.jbc.2021.100455] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 02/06/2023] Open
Abstract
The checkpoint kinase ATR regulates DNA repair, cell cycle progression, and other DNA damage and replication stress responses. ATR signaling is stimulated by an ATR activating protein, and in metazoan cells, there are at least two ATR activators: TOPBP1 and ETAA1. Current evidence indicates TOPBP1 and ETAA1 activate ATR via the same biochemical mechanism, but several aspects of this mechanism remain undefined. For example, ATR and its obligate binding partner ATR interacting protein (ATRIP) form a tetrameric complex consisting of two ATR and two ATRIP molecules, but whether TOPBP1 or ETAA1 dimerization is similarly required for ATR function is unclear. Here, we show that fusion of the TOPBP1 and ETAA1 ATR activation domains (AADs) to dimeric tags makes them more potent activators of ATR in vitro. Furthermore, induced dimerization of both AADs using chemical dimerization of a modified FKBP tag enhances ATR kinase activation and signaling in cells. ETAA1 forms oligomeric complexes mediated by regions of the protein that are predicted to be intrinsically disordered. Induced dimerization of a “mini-ETAA1” protein that contains the AAD and Replication Protein A (RPA) interaction motifs enhances ATR signaling, rescues cellular hypersensitivity to DNA damaging agents, and suppresses micronuclei formation in ETAA1-deficient cells. Together, our results indicate that TOPBP1 and ETAA1 dimerization is important for optimal ATR signaling and genome stability.
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Affiliation(s)
- Vaughn Thada
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville Tennessee, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville Tennessee, USA.
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