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Danovski G, Panova G, Keister B, Georgiev G, Atemin A, Uzunova S, Stamatov R, Kanev PB, Aleksandrov R, Blagoev KB, Stoynov SS. Diffusion of activated ATM explains γH2AX and MDC1 spread beyond the DNA damage site. iScience 2024; 27:110826. [PMID: 39310780 PMCID: PMC11416226 DOI: 10.1016/j.isci.2024.110826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/12/2024] [Accepted: 08/22/2024] [Indexed: 09/25/2024] Open
Abstract
During DNA repair, ATM-induced H2AX histone phosphorylation and MDC1 recruitment spread megabases beyond the damage site. While loop extrusion has been suggested to drive this spread, the underlying mechanism remains unclear. Herein, we provide two lines of evidence that loop extrusion is not the only driver of damage-induced γH2AX spread. First, cohesin loader NIPBL and cohesin subunit RAD21 accumulate considerably later than the phosphorylation of H2AX and MDC1 recruitment at micro-IR-induced damage. Second, auxin-induced RAD21 depletion does not affect γH2AX/MDC1 spread following micro-irradiation or DSB induction by zeocin. To determine if diffusion of activated ATM could account for the observed behavior, we measured the exchange rate and diffusion constants of ATM and MDC1 within damaged and unperturbed chromatin. Using these measurements, we introduced a quantitative model in which the freely diffusing activated ATM phosphorylates H2AX. This model faithfully describes the dynamics of ATM and subsequent γH2AX/MDC1 spread at complex DNA lesions.
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Affiliation(s)
- Georgi Danovski
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
| | | | | | - Georgi Georgiev
- Faculty of Mathematics and Informatics, Sofia University, St. Kliment Ohridski, 5 James Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Aleksandar Atemin
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
| | - Sonya Uzunova
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
| | - Rumen Stamatov
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
| | - Petar-Bogomil Kanev
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
| | - Radoslav Aleksandrov
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
| | - Krastan B. Blagoev
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
- National Science Foundation, Alexandria, VA 22230, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Paris, France
| | - Stoyno S. Stoynov
- Institute of Molecular Biology, Bulgarian Academy of Sciences, 21, G. Bontchev Str, 1113 Sofia, Bulgaria
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Atemin A, Ivanova A, Kanev PB, Uzunova S, Nedelcheva-Veleva M, Stoynov S. Dynamics of Replication-Associated Protein Levels through the Cell Cycle. Int J Mol Sci 2024; 25:8230. [PMID: 39125800 PMCID: PMC11311332 DOI: 10.3390/ijms25158230] [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: 06/25/2024] [Revised: 07/25/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
The measurement of dynamic changes in protein level and localization throughout the cell cycle is of major relevance to studies of cellular processes tightly coordinated with the cycle, such as replication, transcription, DNA repair, and checkpoint control. Currently available methods include biochemical assays of cells in bulk following synchronization, which determine protein levels with poor temporal and no spatial resolution. Taking advantage of genetic engineering and live-cell microscopy, we performed time-lapse imaging of cells expressing fluorescently tagged proteins under the control of their endogenous regulatory elements in order to follow their levels throughout the cell cycle. We effectively discern between cell cycle phases and S subphases based on fluorescence intensity and distribution of co-expressed proliferating cell nuclear antigen (PCNA)-mCherry. This allowed us to precisely determine and compare the levels and distribution of multiple replication-associated factors, including Rap1-interacting factor 1 (RIF1), minichromosome maintenance complex component 6 (MCM6), origin recognition complex subunit 1 (ORC1, and Claspin, with high spatiotemporal resolution in HeLa Kyoto cells. Combining these data with available mass spectrometry-based measurements of protein concentrations reveals the changes in the concentration of these proteins throughout the cell cycle. Our approach provides a practical basis for a detailed interrogation of protein dynamics in the context of the cell cycle.
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Affiliation(s)
| | | | | | | | | | - Stoyno Stoynov
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G., Bonchev Str. Bl. 21, 1113 Sofia, Bulgaria; (A.A.); (A.I.); (P.-B.K.); (S.U.); (M.N.-V.)
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3
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Lange SM, McFarland MR, Lamoliatte F, Carroll T, Krshnan L, Pérez-Ràfols A, Kwasna D, Shen L, Wallace I, Cole I, Armstrong LA, Knebel A, Johnson C, De Cesare V, Kulathu Y. VCP/p97-associated proteins are binders and debranching enzymes of K48-K63-branched ubiquitin chains. Nat Struct Mol Biol 2024:10.1038/s41594-024-01354-y. [PMID: 38977901 DOI: 10.1038/s41594-024-01354-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 06/13/2024] [Indexed: 07/10/2024]
Abstract
Branched ubiquitin (Ub) chains constitute a sizable fraction of Ub polymers in human cells. Despite their abundance, our understanding of branched Ub function in cell signaling has been stunted by the absence of accessible methods and tools. Here we identify cellular branched-chain-specific binding proteins and devise approaches to probe K48-K63-branched Ub function. We establish a method to monitor cleavage of linkages within complex Ub chains and unveil ATXN3 and MINDY as debranching enzymes. We engineer a K48-K63 branch-specific nanobody and reveal the molecular basis of its specificity in crystal structures of nanobody-branched Ub chain complexes. Using this nanobody, we detect increased K48-K63-Ub branching following valosin-containing protein (VCP)/p97 inhibition and after DNA damage. Together with our discovery that multiple VCP/p97-associated proteins bind to or debranch K48-K63-linked Ub, these results suggest a function for K48-K63-branched chains in VCP/p97-related processes.
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Affiliation(s)
- Sven M Lange
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK.
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
| | - Matthew R McFarland
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Frederic Lamoliatte
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Thomas Carroll
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Logesvaran Krshnan
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Anna Pérez-Ràfols
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Dominika Kwasna
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
- Malopolska Centre of Biotechnology (MCB), Jagiellonian University, Krakow, Poland
| | - Linnan Shen
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Iona Wallace
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Isobel Cole
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Lee A Armstrong
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Axel Knebel
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Clare Johnson
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Virginia De Cesare
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Yogesh Kulathu
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK.
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4
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Kanev PB, Varhoshkova S, Georgieva I, Lukarska M, Kirova D, Danovski G, Stoynov S, Aleksandrov R. A unified mechanism for PARP inhibitor-induced PARP1 chromatin retention at DNA damage sites in living cells. Cell Rep 2024; 43:114234. [PMID: 38758646 DOI: 10.1016/j.celrep.2024.114234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 03/20/2024] [Accepted: 04/26/2024] [Indexed: 05/19/2024] Open
Abstract
Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) not only suppress PARP1 catalytic activity but also prolong its association to damaged chromatin. Here, through live-cell imaging, we quantify the alterations in PARP1 dynamics and activity elicited by seven PARPis over a wide range of concentrations to deliver a unified mechanism of PARPi-induced PARP1 chromatin retention. We find that gross PARP1 retention at DNA damage sites is jointly governed by catalytic inhibition and allosteric trapping, albeit in a strictly independent manner-catalytic inhibition causes multiple unproductive binding-dissociation cycles of PARP1, while allosteric trapping prolongs the lesion-bound state of PARP1 to greatly increase overall retention. Importantly, stronger PARP1 retention produces greater temporal shifts in downstream DNA repair events and superior cytotoxicity, highlighting PARP1 retention, a complex but precisely quantifiable characteristic of PARPis, as a valuable biomarker for PARPi efficacy. Our approach can be promptly repurposed for interrogating the properties of DNA-repair-targeting compounds beyond PARPis.
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Affiliation(s)
- Petar-Bogomil Kanev
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria
| | - Sylvia Varhoshkova
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria
| | - Irina Georgieva
- Transmembrane Signaling Laboratory, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria
| | - Maria Lukarska
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Dilyana Kirova
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria
| | - Georgi Danovski
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria
| | - Stoyno Stoynov
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria.
| | - Radoslav Aleksandrov
- Laboratory of Genomic Stability, Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl.21, 1113 Sofia, Bulgaria.
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5
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Krachmarova E, Petkov P, Lilkova E, Stoynova D, Malinova K, Hristova R, Gospodinov A, Ilieva N, Nacheva G, Litov L. Interferon- γ as a Potential Inhibitor of SARS-CoV-2 ORF6 Accessory Protein. Int J Mol Sci 2024; 25:2155. [PMID: 38396843 PMCID: PMC10889309 DOI: 10.3390/ijms25042155] [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: 01/02/2024] [Revised: 02/06/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
The ORF6 protein of the SARS-CoV-2 virus plays a crucial role in blocking the innate immune response of the infected cells by inhibiting interferon pathways. Additionally, it binds to and immobilises the RAE1 protein on the cytoplasmic membranes, thereby blocking mRNA transport from the nucleus to the cytoplasm. In all these cases, the host cell proteins are tethered by the flexible C-terminus of ORF6. A possible strategy to inhibit the biological activity of ORF6 is to bind its C-terminus with suitable ligands. Our in silico experiments suggest that hIFNγ binds the ORF6 protein with high affinity, thus impairing its interactions with RAE1 and, consequently, its activity in viral invasion. The in vitro studies reported here reveal a shift of the localisation of RAE1 in ORF6 overexpressing cells upon treatment with hIFNγ from predominantly cytoplasmic to mainly nuclear, resulting in the restoration of the export of mRNA from the nucleus. We also explored the expression of GFP in transfected-with-ORF6 cells by means of fluorescence microscopy and qRT-PCR, finding that treatment with hIFNγ unblocks the mRNA trafficking and reinstates the GFP expression level. The ability of the cytokine to block ORF6 is also reflected in minimising its negative effects on DNA replication by reducing accumulated RNA-DNA hybrids. Our results, therefore, suggest hIFNγ as a promising inhibitor of the most toxic SARS-CoV-2 protein.
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Affiliation(s)
- Elena Krachmarova
- Institute of Molecular Biology “Roumen Tsanev”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.M.); (R.H.); (A.G.); (G.N.)
| | - Peicho Petkov
- Faculty of Physics, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria (L.L.)
| | - Elena Lilkova
- Institute of Information and Communication Technologies, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (E.L.); (N.I.)
| | - Dayana Stoynova
- Faculty of Physics, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria (L.L.)
| | - Kristina Malinova
- Institute of Molecular Biology “Roumen Tsanev”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.M.); (R.H.); (A.G.); (G.N.)
| | - Rossitsa Hristova
- Institute of Molecular Biology “Roumen Tsanev”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.M.); (R.H.); (A.G.); (G.N.)
| | - Anastas Gospodinov
- Institute of Molecular Biology “Roumen Tsanev”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.M.); (R.H.); (A.G.); (G.N.)
| | - Nevena Ilieva
- Institute of Information and Communication Technologies, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (E.L.); (N.I.)
| | - Genoveva Nacheva
- Institute of Molecular Biology “Roumen Tsanev”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (K.M.); (R.H.); (A.G.); (G.N.)
| | - Leandar Litov
- Faculty of Physics, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria (L.L.)
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