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Raimer Young HM, Hou PC, Bartosik AR, Atkin ND, Wang L, Wang Z, Ratan A, Zang C, Wang YH. DNA fragility at topologically associated domain boundaries is promoted by alternative DNA secondary structure and topoisomerase II activity. Nucleic Acids Res 2024; 52:3837-3855. [PMID: 38452213 DOI: 10.1093/nar/gkae164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/03/2024] [Accepted: 02/23/2024] [Indexed: 03/09/2024] Open
Abstract
CCCTC-binding factor (CTCF) binding sites are hotspots of genome instability. Although many factors have been associated with CTCF binding site fragility, no study has integrated all fragility-related factors to understand the mechanism(s) of how they work together. Using an unbiased, genome-wide approach, we found that DNA double-strand breaks (DSBs) are enriched at strong, but not weak, CTCF binding sites in five human cell types. Energetically favorable alternative DNA secondary structures underlie strong CTCF binding sites. These structures coincided with the location of topoisomerase II (TOP2) cleavage complex, suggesting that DNA secondary structure acts as a recognition sequence for TOP2 binding and cleavage at CTCF binding sites. Furthermore, CTCF knockdown significantly increased DSBs at strong CTCF binding sites and at CTCF sites that are located at topologically associated domain (TAD) boundaries. TAD boundary-associated CTCF sites that lost CTCF upon knockdown displayed increased DSBs when compared to the gained sites, and those lost sites are overrepresented with G-quadruplexes, suggesting that the structures act as boundary insulators in the absence of CTCF, and contribute to increased DSBs. These results model how alternative DNA secondary structures facilitate recruitment of TOP2 to CTCF binding sites, providing mechanistic insight into DNA fragility at CTCF binding sites.
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Affiliation(s)
- Heather M Raimer Young
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
| | - Pei-Chi Hou
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
| | - Anna R Bartosik
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
| | - Naomi D Atkin
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
| | - Lixin Wang
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA
| | - Zhenjia Wang
- Center for Public Health Genomics, University of Virginia School of Medicine, Charlottesville, VA 22908-0717, USA
| | - Aakrosh Ratan
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
- Center for Public Health Genomics, University of Virginia School of Medicine, Charlottesville, VA 22908-0717, USA
- Department of Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- University of Virginia Comprehensive Cancer Center, Charlottesville, VA 22908, USA
| | - Chongzhi Zang
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
- Center for Public Health Genomics, University of Virginia School of Medicine, Charlottesville, VA 22908-0717, USA
- Department of Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- University of Virginia Comprehensive Cancer Center, Charlottesville, VA 22908, USA
| | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA
- University of Virginia Comprehensive Cancer Center, Charlottesville, VA 22908, USA
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Gumina JM, Richardson AE, Shojiv MH, Chambers AE, Sandwith SN, Reisinger MA, Karns TJ, Osborne TL, Alashi HN, Anderson QT, Sharlow ME, Seiler DC, Rogers EM, Bartosik AR, Smaldino MA, Vaughn JP, Wang YH, Smaldino PJ, Haney RA. Differential Gene Expression following DHX36/ G4R1 Knockout Is Associated with G-Quadruplex Content and Cancer. Int J Mol Sci 2024; 25:1753. [PMID: 38339029 PMCID: PMC10855491 DOI: 10.3390/ijms25031753] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/18/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
G-quadruplexes (G4s) are secondary DNA and RNA structures stabilized by positive cations in a central channel formed by stacked tetrads of Hoogsteen base-paired guanines. G4s form from G-rich sequences across the genome, whose biased distribution in regulatory regions points towards a gene-regulatory role. G4s can themselves be regulated by helicases, such as DHX36 (aliases: G4R1 and RHAU), which possess the necessary activity to resolve these stable structures. G4s have been shown to both positively and negatively regulate gene expression when stabilized by ligands, or through the loss of helicase activity. Using DHX36 knockout Jurkat cell lines, we identified widespread, although often subtle, effects on gene expression that are associated with the presence or number of observed G-quadruplexes in promoters or gene regions. Genes that significantly change their expression, particularly those that show a significant increase in RNA abundance under DHX36 knockout, are associated with a range of cellular functions and processes, including numerous transcription factors and oncogenes, and are linked to several cancers. Our work highlights the direct and indirect role of DHX36 in the transcriptome of T-lymphocyte leukemia cells and the potential for DHX36 dysregulation in cancer.
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Affiliation(s)
- Joseph M. Gumina
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | | | | | | | | | | | - Taylor J. Karns
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | - Tyler L. Osborne
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | - Hasna N. Alashi
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | | | | | - Dylan C. Seiler
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | - Evan M. Rogers
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | - Anna R. Bartosik
- School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | | | | | - Yuh-Hwa Wang
- School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | | | - Robert A. Haney
- Department of Biology, Ball State University, Muncie, IN 47306, USA
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