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Wang X, Yue F. Hijacked enhancer-promoter and silencer-promoter loops in cancer. Curr Opin Genet Dev 2024; 86:102199. [PMID: 38669773 DOI: 10.1016/j.gde.2024.102199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 03/19/2024] [Accepted: 04/07/2024] [Indexed: 04/28/2024]
Abstract
Recent work has shown that besides inducing fusion genes, structural variations (SVs) can also contribute to oncogenesis by disrupting the three-dimensional genome organization and dysregulating gene expression. At the chromatin-loop level, SVs can relocate enhancers or silencers from their original genomic loci to activate oncogenes or repress tumor suppressor genes. On a larger scale, different types of alterations in topologically associating domains (TADs) have been reported in cancer, such as TAD expansion, shuffling, and SV-induced neo-TADs. Furthermore, the transformation from normal cells to cancerous cells is usually coupled with active or repressive compartmental switches, and cancer-specific compartments have been proposed. This review discusses the sites, and the other latest advances in studying how SVs disrupt higher-order genome structure in cancer, which in turn leads to oncogene dysregulation. We also highlight the clinical implications of these changes and the challenges ahead in this field.
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Affiliation(s)
- Xiaotao Wang
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China; Shanghai Key Laboratory of Reproduction and Development, Shanghai, China.
| | - Feng Yue
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine Northwestern University, Chicago, Illinois, USA; Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois, USA.
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Qin Y, Meng FL. Taming AID mutator activity in somatic hypermutation. Trends Biochem Sci 2024:S0968-0004(24)00077-X. [PMID: 38614818 DOI: 10.1016/j.tibs.2024.03.011] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 03/05/2024] [Accepted: 03/19/2024] [Indexed: 04/15/2024]
Abstract
Activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) by introducing base substitutions into antibody genes, a process enabling antibody affinity maturation in immune response. How a mutator is tamed to precisely and safely generate programmed DNA lesions in a physiological process remains unsettled, as its dysregulation drives lymphomagenesis. Recent research has revealed several hidden features of AID-initiated mutagenesis: preferential activity on flexible DNA substrates, restrained activity within chromatin loop domains, unique DNA repair factors to differentially decode AID-caused lesions, and diverse consequences of aberrant deamination. Here, we depict the multifaceted regulation of AID activity with a focus on emerging concepts/factors and discuss their implications for the design of base editors (BEs) that install somatic mutations to correct deleterious genomic variants.
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Affiliation(s)
- Yining Qin
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences; Shanghai 200031, China
| | - Fei-Long Meng
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences; Shanghai 200031, China.
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Lauring MC, Basu U. Somatic hypermutation mechanisms during lymphomagenesis and transformation. Curr Opin Genet Dev 2024; 85:102165. [PMID: 38428317 DOI: 10.1016/j.gde.2024.102165] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 03/03/2024]
Abstract
B cells undergoing physiologically programmed or aberrant genomic alterations provide an opportune system to study the causes and consequences of genome mutagenesis. Activated B cells in germinal centers express activation-induced cytidine deaminase (AID) to accomplish physiological somatic hypermutation (SHM) of their antibody-encoding genes. In attempting to diversify their immunoglobulin (Ig) heavy- and light-chain genes, several B-cell clones successfully optimize their antigen-binding affinities. However, SHM can sometimes occur at non-Ig loci, causing genetic alternations that lay the foundation for lymphomagenesis, particularly diffuse large B-cell lymphoma. Thus, SHM acts as a double-edged sword, bestowing superb humoral immunity at the potential risk of initiating disease. We refer to off-target, non-Ig AID mutations - that are often but not always associated with disease - as aberrant SHM (aSHM). A key challenge in understanding SHM and aSHM is determining how AID targets and mutates specific DNA sequences in the Ig loci to generate antibody diversity and non-Ig genes to initiate lymphomagenesis. Herein, we discuss some current advances regarding the regulation of AID's DNA mutagenesis activity in B cells.
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Affiliation(s)
- Max C Lauring
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York 10032, USA.
| | - Uttiya Basu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York 10032, USA.
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Dauba A, Näser E, Andrieux D, Cogné M, Denizot Y, Khamlichi AA. The immunoglobulin heavy chain super enhancer controls class switch recombination in developing B cells. Sci Rep 2024; 14:7370. [PMID: 38548819 PMCID: PMC10979011 DOI: 10.1038/s41598-024-57576-z] [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: 12/08/2023] [Accepted: 03/19/2024] [Indexed: 04/01/2024] Open
Abstract
Class switch recombination (CSR) plays an important role in adaptive immune response by enabling mature B cells to replace the initial IgM by another antibody class (IgG, IgE or IgA). CSR is preceded by transcription of the IgH constant genes and is controlled by the super-enhancer 3' regulatory region (3'RR) in an activation-specific manner. The 3'RR is composed of four enhancers (hs3a, hs1-2, hs3b and hs4). In mature B cells, 3'RR activity correlates with transcription of its enhancers. CSR can also occur in primary developing B cells though at low frequency, but in contrast to mature B cells, the transcriptional elements that regulate the process in developing B cells are ill-known. In particular, the role of the 3'RR in the control of constant genes' transcription and CSR has not been addressed. Here, by using a mouse line devoid of the 3'RR and a culture system that highly enriches in pro-B cells, we show that the 3'RR activity is indeed required for switch transcription and CSR, though its effect varies in an isotype-specific manner and correlates with transcription of hs4 enhancer only.
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Affiliation(s)
- Audrey Dauba
- Institut de Pharmacologie Et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), CNRS UMR5089, 205 Route de Narbonne, BP 64182, 31077, Toulouse, France
| | - Emmanuelle Näser
- Institut de Pharmacologie Et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), CNRS UMR5089, 205 Route de Narbonne, BP 64182, 31077, Toulouse, France
| | - Dylan Andrieux
- Institut de Pharmacologie Et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), CNRS UMR5089, 205 Route de Narbonne, BP 64182, 31077, Toulouse, France
| | - Michel Cogné
- MOBIDIC, INSERM U1236, Université de Rennes 1, Rennes, France
| | - Yves Denizot
- UMR CNRS 7276, INSERM U1262, Université de Limoges, CBRS, Limoges, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie Et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), CNRS UMR5089, 205 Route de Narbonne, BP 64182, 31077, Toulouse, France.
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Malzl D, Peycheva M, Rahjouei A, Gnan S, Klein KN, Nazarova M, Schoeberl UE, Gilbert DM, Buonomo SCB, Di Virgilio M, Neumann T, Pavri R. RIF1 regulates early replication timing in murine B cells. Nat Commun 2023; 14:8049. [PMID: 38081811 PMCID: PMC10713614 DOI: 10.1038/s41467-023-43778-y] [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: 04/27/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
The mammalian DNA replication timing (RT) program is crucial for the proper functioning and integrity of the genome. The best-known mechanism for controlling RT is the suppression of late origins of replication in heterochromatin by RIF1. Here, we report that in antigen-activated, hypermutating murine B lymphocytes, RIF1 binds predominantly to early-replicating active chromatin and promotes early replication, but plays a minor role in regulating replication origin activity, gene expression and genome organization in B cells. Furthermore, we find that RIF1 functions in a complementary and non-epistatic manner with minichromosome maintenance (MCM) proteins to establish early RT signatures genome-wide and, specifically, to ensure the early replication of highly transcribed genes. These findings reveal additional layers of regulation within the B cell RT program, driven by the coordinated activity of RIF1 and MCM proteins.
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Affiliation(s)
- Daniel Malzl
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030, Vienna, Austria
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090, Lazarettgasse 14, Vienna, Austria
| | - Mihaela Peycheva
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030, Vienna, Austria
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090, Lazarettgasse 14, Vienna, Austria
| | - Ali Rahjouei
- Max-Delbruck Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Stefano Gnan
- School of Biological Sciences, Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3FF, UK
| | - Kyle N Klein
- San Diego Biomedical Research Institute, San Diego, CA, 92121, USA
| | - Mariia Nazarova
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030, Vienna, Austria
| | - Ursula E Schoeberl
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030, Vienna, Austria
| | - David M Gilbert
- San Diego Biomedical Research Institute, San Diego, CA, 92121, USA
| | - Sara C B Buonomo
- School of Biological Sciences, Institute of Cell Biology, University of Edinburgh, Edinburgh, EH9 3FF, UK
| | - Michela Di Virgilio
- Max-Delbruck Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
| | - Tobias Neumann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030, Vienna, Austria.
- Quantro Therapeutics, Vienna Biocenter, 1030, Vienna, Austria.
| | - Rushad Pavri
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030, Vienna, Austria.
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