1
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Székvölgyi L. Chromosomal R-loops: who R they? Biol Futur 2024; 75:177-182. [PMID: 38457033 DOI: 10.1007/s42977-024-00213-7] [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: 11/19/2023] [Accepted: 02/14/2024] [Indexed: 03/09/2024]
Abstract
R-loops, composed of DNA-RNA hybrids and displaced single-stranded DNA, are known to pose a severe threat to genome integrity. Therefore, extensive research has focused on identifying regulatory proteins involved in controlling R-loop levels. These proteins play critical roles in preventing R-loop accumulation and associated genome instability. Herein I summarize recent knowledge on R-loop regulators affecting R-loop homeostasis, involving a wide array of R-loop screening methods that have enabled their characterization, from forward genetic and siRNA-based screens to proximity labeling and machine learning. These approaches not only deepen our understanding on R-loop formation processes, but also hold promise to find new targets in R-loop dysregulation associated with human pathologies.
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Affiliation(s)
- Lóránt Székvölgyi
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Department of Molecular and Nanopharmaceutics, Faculty of Pharmacy, University of Debrecen, Debrecen, 4032, Hungary.
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2
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Wang Y, Gao B, Zhang L, Wang X, Zhu X, Yang H, Zhang F, Zhu X, Zhou B, Yao S, Nagayama A, Lee S, Ouyang J, Koh SB, Eisenhauer EL, Zarrella D, Lu K, Rueda BR, Zou L, Su XA, Yeku O, Ellisen LW, Wang XS, Lan L. Meiotic protein SYCP2 confers resistance to DNA-damaging agents through R-loop-mediated DNA repair. Nat Commun 2024; 15:1568. [PMID: 38383600 PMCID: PMC10881575 DOI: 10.1038/s41467-024-45693-2] [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: 02/10/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
Drugs targeting the DNA damage response (DDR) are widely used in cancer therapy, but resistance to these drugs remains a major clinical challenge. Here, we show that SYCP2, a meiotic protein in the synaptonemal complex, is aberrantly and commonly expressed in breast and ovarian cancers and associated with broad resistance to DDR drugs. Mechanistically, SYCP2 enhances the repair of DNA double-strand breaks (DSBs) through transcription-coupled homologous recombination (TC-HR). SYCP2 promotes R-loop formation at DSBs and facilitates RAD51 recruitment independently of BRCA1. SYCP2 loss impairs RAD51 localization, reduces TC-HR, and renders tumors sensitive to PARP and topoisomerase I (TOP1) inhibitors. Furthermore, our studies of two clinical cohorts find that SYCP2 overexpression correlates with breast cancer resistance to antibody-conjugated TOP1 inhibitor and ovarian cancer resistance to platinum treatment. Collectively, our data suggest that SYCP2 confers cancer cell resistance to DNA-damaging agents by stimulating R-loop-mediated DSB repair, offering opportunities to improve DDR therapy.
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Affiliation(s)
- Yumin Wang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Boya Gao
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
- Department of Molecular Biology and Microbiology, Duke University School of Medicine, 213 Research Drive, Durham, NC, 27710, USA
| | - Luyuan Zhang
- Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Xudong Wang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Xiaolan Zhu
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Haibo Yang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Fengqi Zhang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
- Department of Molecular Biology and Microbiology, Duke University School of Medicine, 213 Research Drive, Durham, NC, 27710, USA
| | - Xueping Zhu
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Badi Zhou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Sean Yao
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Aiko Nagayama
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
- Ludwig Center at Harvard, Boston, MA, 02215, USA
| | - Sanghoon Lee
- UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Ave, Pittsburgh, PA, 15232, USA
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, 15232, USA
- Department of Biomedical Informatics, University of Pittsburgh, Pittsburgh, PA, 15232, USA
| | - Jian Ouyang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
| | - Siang-Boon Koh
- School of Cellular & Molecular Medicine, University of Bristol; University Walk, Bristol, BS8 1TD, UK
| | - Eric L Eisenhauer
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, 55 Fruit St, Massachusetts General Hospital, Boston, MA, 02114, USA
- Obstetrics, Gynecology and Reproductive Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Dominique Zarrella
- Vincent Center for Reproductive Biology, Department of Obstetrics and Gynecology, 55 Fruit St, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Kate Lu
- David H. Koch Institute for Integrative Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Bo R Rueda
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, 55 Fruit St, Massachusetts General Hospital, Boston, MA, 02114, USA
- Obstetrics, Gynecology and Reproductive Biology, Harvard Medical School, Boston, MA, 02115, USA
- Vincent Center for Reproductive Biology, Department of Obstetrics and Gynecology, 55 Fruit St, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, Boston, MA, 02114, USA
- Department of Pharmacology & Cancer Biology, Duke University School of Medicine, 213 Research Drive, Durham, NC, 27710, USA
| | - Xiaofeng A Su
- David H. Koch Institute for Integrative Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Oladapo Yeku
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
- Division of Hematology-Oncology, Massachusetts General Hospital, 55 Fruit St, Boston, MA, 02114, USA
- Department of Medicine, Massachusetts General Hospital, 55 Fruit St, Boston, MA, 02114, USA
| | - Leif W Ellisen
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA
- Ludwig Center at Harvard, Boston, MA, 02215, USA
| | - Xiao-Song Wang
- UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Ave, Pittsburgh, PA, 15232, USA
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, 15232, USA
- Department of Biomedical Informatics, University of Pittsburgh, Pittsburgh, PA, 15232, USA
| | - Li Lan
- Massachusetts General Hospital Cancer Center, Harvard Medical School, 13th Street, Charlestown, MA, 02129, USA.
- Department of Molecular Biology and Microbiology, Duke University School of Medicine, 213 Research Drive, Durham, NC, 27710, USA.
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3
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Kumar C, Remus D. Looping out of control: R-loops in transcription-replication conflict. Chromosoma 2024; 133:37-56. [PMID: 37419963 PMCID: PMC10771546 DOI: 10.1007/s00412-023-00804-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/09/2023]
Abstract
Transcription-replication conflict is a major cause of replication stress that arises when replication forks collide with the transcription machinery. Replication fork stalling at sites of transcription compromises chromosome replication fidelity and can induce DNA damage with potentially deleterious consequences for genome stability and organismal health. The block to DNA replication by the transcription machinery is complex and can involve stalled or elongating RNA polymerases, promoter-bound transcription factor complexes, or DNA topology constraints. In addition, studies over the past two decades have identified co-transcriptional R-loops as a major source for impairment of DNA replication forks at active genes. However, how R-loops impede DNA replication at the molecular level is incompletely understood. Current evidence suggests that RNA:DNA hybrids, DNA secondary structures, stalled RNA polymerases, and condensed chromatin states associated with R-loops contribute to the of fork progression. Moreover, since both R-loops and replication forks are intrinsically asymmetric structures, the outcome of R-loop-replisome collisions is influenced by collision orientation. Collectively, the data suggest that the impact of R-loops on DNA replication is highly dependent on their specific structural composition. Here, we will summarize our current understanding of the molecular basis for R-loop-induced replication fork progression defects.
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Affiliation(s)
- Charanya Kumar
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, 10065, USA
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, 10065, USA.
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4
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Gómez-González B, Aguilera A. Break-induced RNA-DNA hybrids (BIRDHs) in homologous recombination: friend or foe? EMBO Rep 2023; 24:e57801. [PMID: 37818834 DOI: 10.15252/embr.202357801] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/29/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023] Open
Abstract
Double-strand breaks (DSBs) are the most harmful DNA lesions, with a strong impact on cell proliferation and genome integrity. Depending on cell cycle stage, DSBs are preferentially repaired by non-homologous end joining or homologous recombination (HR). In recent years, numerous reports have revealed that DSBs enhance DNA-RNA hybrid formation around the break site. We call these hybrids "break-induced RNA-DNA hybrids" (BIRDHs) to differentiate them from sporadic R-loops consisting of DNA-RNA hybrids and a displaced single-strand DNA occurring co-transcriptionally in intact DNA. Here, we review and discuss the most relevant data about BIRDHs, with a focus on two main questions raised: (i) whether BIRDHs form by de novo transcription after a DSB or by a pre-existing nascent RNA in DNA regions undergoing transcription and (ii) whether they have a positive role in HR or are just obstacles to HR accidentally generated as an intrinsic risk of transcription. We aim to provide a comprehensive view of the exciting and yet unresolved questions about the source and impact of BIRDHs in the cell.
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Affiliation(s)
- Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Seville, Spain
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5
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Fernandes RV, Lingner J. The THO complex counteracts TERRA R-loop-mediated telomere fragility in telomerase+ cells and telomeric recombination in ALT+ cells. Nucleic Acids Res 2023; 51:6702-6722. [PMID: 37246640 PMCID: PMC10359610 DOI: 10.1093/nar/gkad448] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 04/26/2023] [Accepted: 05/14/2023] [Indexed: 05/30/2023] Open
Abstract
Telomeres are the nucleoprotein structures at the ends of linear chromosomes. Telomeres are transcribed into long non-coding Telomeric Repeat-Containing RNA (TERRA), whose functions rely on its ability to associate with telomeric chromatin. The conserved THO complex (THOC) was previously identified at human telomeres. It links transcription with RNA processing, decreasing the accumulation of co-transcriptional DNA:RNA hybrids throughout the genome. Here, we explore the role of THOC at human telomeres, as a regulator of TERRA localization to chromosome ends. We show that THOC counteracts TERRA association with telomeres via R-loops formed co-transcriptionally and also post-transcriptionally, in trans. We demonstrate that THOC binds nucleoplasmic TERRA, and that RNaseH1 loss, which increases telomeric R-loops, promotes THOC occupancy at telomeres. Additionally, we show that THOC counteracts lagging and mainly leading strand telomere fragility, suggesting that TERRA R-loops can interfere with replication fork progression. Finally, we observed that THOC suppresses telomeric sister-chromatid exchange and C-circle accumulation in ALT cancer cells, which maintain telomeres by recombination. Altogether, our findings reveal crucial roles of THOC in telomeric homeostasis through the co- and post-transcriptional regulation of TERRA R-loops.
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Affiliation(s)
- Rita Valador Fernandes
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Joachim Lingner
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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6
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Thomas M, Dubacq C, Rabut E, Lopez BS, Guirouilh-Barbat J. Noncanonical Roles of RAD51. Cells 2023; 12:cells12081169. [PMID: 37190078 DOI: 10.3390/cells12081169] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 05/17/2023] Open
Abstract
Homologous recombination (HR), an evolutionary conserved pathway, plays a paramount role(s) in genome plasticity. The pivotal HR step is the strand invasion/exchange of double-stranded DNA by a homologous single-stranded DNA (ssDNA) covered by RAD51. Thus, RAD51 plays a prime role in HR through this canonical catalytic strand invasion/exchange activity. The mutations in many HR genes cause oncogenesis. Surprisingly, despite its central role in HR, the invalidation of RAD51 is not classified as being cancer prone, constituting the "RAD51 paradox". This suggests that RAD51 exercises other noncanonical roles that are independent of its catalytic strand invasion/exchange function. For example, the binding of RAD51 on ssDNA prevents nonconservative mutagenic DNA repair, which is independent of its strand exchange activity but relies on its ssDNA occupancy. At the arrested replication forks, RAD51 plays several noncanonical roles in the formation, protection, and management of fork reversal, allowing for the resumption of replication. RAD51 also exhibits noncanonical roles in RNA-mediated processes. Finally, RAD51 pathogenic variants have been described in the congenital mirror movement syndrome, revealing an unexpected role in brain development. In this review, we present and discuss the different noncanonical roles of RAD51, whose presence does not automatically result in an HR event, revealing the multiple faces of this prominent actor in genomic plasticity.
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Affiliation(s)
- Mélissa Thomas
- INSERM U1016, UMR 8104 CNRS, Institut Cochin, Université de Paris Cité, 24 rue du Faubourg St. Jacques, F-75014 Paris, France
| | - Caroline Dubacq
- Institut de Biologie Paris Seine, IBPS, Neuroscience Paris Seine, NPS, INSERM, CNRS, Sorbonne Université, F-75005 Paris, France
| | - Elise Rabut
- INSERM U1016, UMR 8104 CNRS, Institut Cochin, Université de Paris Cité, 24 rue du Faubourg St. Jacques, F-75014 Paris, France
| | - Bernard S Lopez
- INSERM U1016, UMR 8104 CNRS, Institut Cochin, Université de Paris Cité, 24 rue du Faubourg St. Jacques, F-75014 Paris, France
| | - Josée Guirouilh-Barbat
- INSERM U1016, UMR 8104 CNRS, Institut Cochin, Université de Paris Cité, 24 rue du Faubourg St. Jacques, F-75014 Paris, France
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7
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Saha S, Pommier Y. R-loops, type I topoisomerases and cancer. NAR Cancer 2023; 5:zcad013. [PMID: 37600974 PMCID: PMC9984992 DOI: 10.1093/narcan/zcad013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/18/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
R-loops are abundant and dynamic structures ubiquitously present in human cells both in the nuclear and mitochondrial genomes. They form in cis in the wake of transcription complexes and in trans apart from transcription complexes. In this review, we focus on the relationship between R-loops and topoisomerases, and cancer genomics and therapies. We summarize the topological parameters associated with the formation and resolution of R-loops, which absorb and release high levels of genomic negative supercoiling (Sc-). We review the deleterious consequences of excessive R-loops and rationalize how human type IA (TOP3B) and type IB (TOP1) topoisomerases regulate and resolve R-loops in coordination with helicase and RNase H enzymes. We also review the drugs (topoisomerase inhibitors, splicing inhibitors, G4 stabilizing ligands) and cancer predisposing genes (BRCA1/2, transcription, and splicing genes) known to induce R-loops, and whether stabilizing R-loops and thereby inducing genomic damage can be viewed as a strategy for cancer treatment.
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Affiliation(s)
- Sourav Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Yves Pommier
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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8
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Cañas JC, García-Rubio ML, García A, Antequera F, Gómez-González B, Aguilera A. A role for the Saccharomyces cerevisiae Rtt109 histone acetyltransferase in R-loop homeostasis and associated genome instability. Genetics 2022; 222:6648348. [PMID: 35866610 PMCID: PMC9434296 DOI: 10.1093/genetics/iyac108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 07/08/2022] [Indexed: 12/02/2022] Open
Abstract
The stability of the genome is occasionally challenged by the formation of DNA–RNA hybrids and R-loops, which can be influenced by the chromatin context. This is mainly due to the fact that DNA–RNA hybrids hamper the progression of replication forks, leading to fork stalling and, ultimately, DNA breaks. Through a specific screening of chromatin modifiers performed in the yeast Saccharomyces cerevisiae, we have found that the Rtt109 histone acetyltransferase is involved in several steps of R-loop-metabolism and their associated genetic instability. On the one hand, Rtt109 prevents DNA–RNA hybridization by the acetylation of histone H3 lysines 14 and 23 and, on the other hand, it is involved in the repair of replication-born DNA breaks, such as those that can be caused by R-loops, by acetylating lysines 14 and 56. In addition, Rtt109 loss renders cells highly sensitive to replication stress in combination with R-loop-accumulating THO-complex mutants. Our data evidence that the chromatin context simultaneously influences the occurrence of DNA–RNA hybrid-associated DNA damage and its repair, adding complexity to the source of R-loop-associated genetic instability.
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Affiliation(s)
- Juan Carlos Cañas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain.,Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - María Luisa García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain.,Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Alicia García
- Instituto de Biología Funcional y Genómica (IBFG), CSIC-Universidad de Salamanca, 37007, Salamanca, Spain
| | - Francisco Antequera
- Instituto de Biología Funcional y Genómica (IBFG), CSIC-Universidad de Salamanca, 37007, Salamanca, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain.,Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC, 41092 Seville, Spain.,Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
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9
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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: 81] [Impact Index Per Article: 40.5] [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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10
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Ou-Yang H, Yang SH, Chen W, Yang SH, Cidem A, Sung LY, Chen CM. Cruciform DNA Structures Act as Legible Templates for Accelerating Homologous Recombination in Transgenic Animals. Int J Mol Sci 2022; 23:3973. [PMID: 35409332 PMCID: PMC9000021 DOI: 10.3390/ijms23073973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 03/27/2022] [Accepted: 03/29/2022] [Indexed: 11/16/2022] Open
Abstract
Inverted repeat (IR) DNA sequences compose cruciform structures. Some genetic disorders are the result of genome inversion or translocation by cruciform DNA structures. The present study examined whether exogenous DNA integration into the chromosomes of transgenic animals was related to cruciform DNA structures. Large imperfect cruciform structures were frequently predicted around predestinated transgene integration sites in host genomes of microinjection-based transgenic (Tg) animals (αLA-LPH Tg goat, Akr1A1eGFP/eGFP Tg mouse, and NFκB-Luc Tg mouse) or CRISPR/Cas9 gene-editing (GE) animals (αLA-AP1 GE mouse). Transgene cassettes were imperfectly matched with their predestinated sequences. According to the analyzed data, we proposed a putative model in which the flexible cruciform DNA structures acted as a legible template for DNA integration into linear DNAs or double-strand break (DSB) alleles. To demonstrate this model, artificial inverted repeat knock-in (KI) reporter plasmids were created to analyze the KI rate using the CRISPR/Cas9 system in NIH3T3 cells. Notably, the KI rate of the 5′ homologous arm inverted repeat donor plasmid (5′IR) with the ROSA gRNA group (31.5%) was significantly higher than the knock-in reporter donor plasmid (KIR) with the ROSA gRNA group (21.3%, p < 0.05). However, the KI rate of the 3′ inverted terminal repeat/inverted repeat donor plasmid (3′ITRIR) group was not different from the KIR group (23.0% vs. 22.0%). These results demonstrated that the legibility of the sequence with the cruciform DNA existing in the transgene promoted homologous recombination (HR) with a higher KI rate. Our findings suggest that flexible cruciform DNAs folded by IR sequences improve the legibility and accelerate DNA 3′-overhang integration into the host genome via homologous recombination machinery.
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Affiliation(s)
- Huan Ou-Yang
- Program in Translational Medicine, Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.); (A.C.)
- Institute of Biotechnology, College of Bioresources and Agriculture, National Taiwan University, Taipei 106, Taiwan
| | - Shiao-Hsuan Yang
- Program in Translational Medicine, Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.); (A.C.)
- Reproductive Medicine Center, Department of Gynecology, Changhua Christian Hospital, Changhua 515, Taiwan
| | - Wei Chen
- Division of Pulmonary and Critical Care Medicine, Chia-Yi Christian Hospital, Chiayi 600, Taiwan;
| | - Shang-Hsun Yang
- Department of Physiology, National Cheng Kung University, Tainan 701, Taiwan;
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Abdulkadir Cidem
- Program in Translational Medicine, Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.); (A.C.)
- Department of Molecular Biology and Genetics, Erzurum Technical University, Erzurum 25250, Turkey
| | - Li-Ying Sung
- Institute of Biotechnology, College of Bioresources and Agriculture, National Taiwan University, Taipei 106, Taiwan
| | - Chuan-Mu Chen
- Program in Translational Medicine, Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.); (A.C.)
- The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
- Rong-Hsing Translational Medicine Research Center, Taichung Veterans General Hospital, Taichung 407, Taiwan
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11
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Abstract
It has recently been demonstrated that budding yeast telomeres are transcribed into TERRA, a long noncoding RNA. Due to the G-rich nature of the coding strand, TERRA has a tendency to form DNA-RNA hybrids and potentially R-loops, which in turn, promote repair at short telomeres. Here, we report two methods to detect DNA-RNA hybrids at yeast telomeres, namely, DRIP, which employs the S9.6 hybrid-recognizing antibody, and R-ChIP, which takes advantage of a catalytic dead form of RNase H1 (Rnh1-cd). We use cross-linked material for both protocols as we have found that this does not negatively affect recovered material, and furthermore allows the precipitation of other proteins from the identical cross-linked material. Although both methods are successful in terms of detecting DNA-RNA hybrids at telomeres, the R-ChIP method yields an approximately ten-fold increased enrichment.
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Affiliation(s)
- Carolin B Wagner
- Institute of Molecular Biology (IMB), Mainz, Germany
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg-University Mainz, Mainz, Germany
| | - Brian Luke
- Institute of Molecular Biology (IMB), Mainz, Germany.
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg-University Mainz, Mainz, Germany.
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12
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Cañas JC, Aguilera A, Gómez-González B. Detection of R-Loops by In Vivo and In Vitro Cytosine Deamination in Saccharomyces cerevisiae. Methods Mol Biol 2022; 2528:39-53. [PMID: 35704184 DOI: 10.1007/978-1-0716-2477-7_4] [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] [Indexed: 06/15/2023]
Abstract
R-loops are transcriptional by-products formed by a hybrid of the nascent RNA molecule with its DNA template and the displaced nontemplate DNA strand. The single stranded nature of the displaced nontemplate strand makes it vulnerable to attack. This property is used in nature to cause directed mutagenesis and breaks by the action of the activation-induced cytosine deaminase (AID) enzyme and can thus be exploited to detect the presence of R-loops even when they form at low frequencies by overexpressing this enzyme in vivo or by in vitro treatment with the bisulfite anion, which further allows nucleotide resolution. This is of particular relevance given the fact that R-loops have the potential to hamper DNA replication and repair, threatening genome integrity. Here, we describe the protocols used in the yeast Saccharomyces cerevisiae to infer the presence of R-loops through increased AID-induced DNA damage, measured as increased recombination or Rad52 foci formation as well as to detect single R-loop molecules and determine their length at particular genomic sites via bisulfite treatment and amplification.
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Affiliation(s)
- Juan C Cañas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain.
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13
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Hurst V, Challa K, Jonas F, Forey R, Sack R, Seebacher J, Schmid CD, Barkai N, Shimada K, Gasser SM, Poli J. A regulatory phosphorylation site on Mec1 controls chromatin occupancy of RNA polymerases during replication stress. EMBO J 2021; 40:e108439. [PMID: 34569643 PMCID: PMC8561635 DOI: 10.15252/embj.2021108439] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 01/16/2023] Open
Abstract
Upon replication stress, budding yeast checkpoint kinase Mec1ATR triggers the downregulation of transcription, thereby reducing the level of RNA polymerase (RNAP) on chromatin to facilitate replication fork progression. Here, we identify a hydroxyurea-induced phosphorylation site on Mec1, Mec1-S1991, that contributes to the eviction of RNAPII and RNAPIII during replication stress. The expression of the non-phosphorylatable mec1-S1991A mutant reduces replication fork progression genome-wide and compromises survival on hydroxyurea. This defect can be suppressed by destabilizing chromatin-bound RNAPII through a TAP fusion to its Rpb3 subunit, suggesting that lethality in mec1-S1991A mutants arises from replication-transcription conflicts. Coincident with a failure to repress gene expression on hydroxyurea in mec1-S1991A cells, highly transcribed genes such as GAL1 remain bound at nuclear pores. Consistently, we find that nuclear pore proteins and factors controlling RNAPII and RNAPIII are phosphorylated in a Mec1-dependent manner on hydroxyurea. Moreover, we show that Mec1 kinase also contributes to reduced RNAPII occupancy on chromatin during an unperturbed S phase by promoting degradation of the Rpb1 subunit.
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Affiliation(s)
- Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Felix Jonas
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Romain Forey
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Ragna Sack
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jan Seebacher
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Christoph D Schmid
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Naama Barkai
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Jérôme Poli
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
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14
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Sanchez A, Lee D, Kim DI, Miller KM. Making Connections: Integrative Signaling Mechanisms Coordinate DNA Break Repair in Chromatin. Front Genet 2021; 12:747734. [PMID: 34659365 PMCID: PMC8514019 DOI: 10.3389/fgene.2021.747734] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/31/2021] [Indexed: 01/25/2023] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous to genome integrity and can promote mutations and disease if not handled correctly. Cells respond to these dangers by engaging DNA damage response (DDR) pathways that are able to identify DNA breaks within chromatin leading ultimately to their repair. The recognition and repair of DSBs by the DDR is largely dependent on the ability of DNA damage sensing factors to bind to and interact with nucleic acids, nucleosomes and their modified forms to target these activities to the break site. These contacts orientate and localize factors to lesions within chromatin, allowing signaling and faithful repair of the break to occur. Coordinating these events requires the integration of several signaling and binding events. Studies are revealing an enormously complex array of interactions that contribute to DNA lesion recognition and repair including binding events on DNA, as well as RNA, RNA:DNA hybrids, nucleosomes, histone and non-histone protein post-translational modifications and protein-protein interactions. Here we examine several DDR pathways that highlight and provide prime examples of these emerging concepts. A combination of approaches including genetic, cellular, and structural biology have begun to reveal new insights into the molecular interactions that govern the DDR within chromatin. While many questions remain, a clearer picture has started to emerge for how DNA-templated processes including transcription, replication and DSB repair are coordinated. Multivalent interactions with several biomolecules serve as key signals to recruit and orientate proteins at DNA lesions, which is essential to integrate signaling events and coordinate the DDR within the milieu of the nucleus where competing genome functions take place. Genome architecture, chromatin structure and phase separation have emerged as additional vital regulatory mechanisms that also influence genome integrity pathways including DSB repair. Collectively, recent advancements in the field have not only provided a deeper understanding of these fundamental processes that maintain genome integrity and cellular homeostasis but have also started to identify new strategies to target deficiencies in these pathways that are prevalent in human diseases including cancer.
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Affiliation(s)
- Anthony Sanchez
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States
| | - Doohyung Lee
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States
| | - Dae In Kim
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States
| | - Kyle M Miller
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States.,Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, TX, United States
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15
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Shaw A, Gullerova M. Home and Away: The Role of Non-Coding RNA in Intracellular and Intercellular DNA Damage Response. Genes (Basel) 2021; 12:1475. [PMID: 34680868 PMCID: PMC8535248 DOI: 10.3390/genes12101475] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 12/14/2022] Open
Abstract
Non-coding RNA (ncRNA) has recently emerged as a vital component of the DNA damage response (DDR), which was previously believed to be solely regulated by proteins. Many species of ncRNA can directly or indirectly influence DDR and enhance DNA repair, particularly in response to double-strand DNA breaks, which may hold therapeutic potential in the context of cancer. These include long non-coding RNA (lncRNA), microRNA, damage-induced lncRNA, DNA damage response small RNA, and DNA:RNA hybrid structures, which can be categorised as cis or trans based on the location of their synthesis relative to DNA damage sites. Mechanisms of RNA-dependent DDR include the recruitment or scaffolding of repair factors at DNA break sites, the regulation of repair factor expression, and the stabilisation of repair intermediates. DDR can also be communicated intercellularly via exosomes, leading to bystander responses in healthy neighbour cells to generate a population-wide response to damage. Many microRNA species have been directly implicated in the propagation of bystander DNA damage, autophagy, and radioresistance, which may prove significant for enhancing cancer treatment via radiotherapy. Here, we review recent developments centred around ncRNA and their contributions to intracellular and intercellular DDR mechanisms.
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Affiliation(s)
| | - Monika Gullerova
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK;
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16
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Abstract
Telomeres protect chromosome ends from nucleolytic degradation, uncontrolled recombination by DNA repair enzymes and checkpoint signaling, and they provide mechanisms for their maintenance by semiconservative DNA replication, telomerase and homologous recombination. The telomeric long noncoding RNA TERRA is transcribed from a large number of chromosome ends. TERRA has been implicated in modulating telomeric chromatin structure and checkpoint signaling, and in telomere maintenance by homology directed repair, and telomerase – when telomeres are damaged or very short. Recent work indicates that TERRA association with telomeres involves the formation of DNA:RNA hybrid structures that can be formed post transcription by the RAD51 DNA recombinase, which in turn may trigger homologous recombination between telomeric repeats and telomere elongation. In this review, we describe the mechanisms of TERRA recruitment to telomeres, R-loop formation and its regulation by shelterin proteins. We discuss the consequences of R-loop formation, with regard to telomere maintenance by DNA recombination and how this may impinge on telomere replication while counteracting telomere shortening in normal cells and in ALT cancer cells, which maintain telomeres in the absence of telomerase.
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Affiliation(s)
- Rita Valador Fernandes
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
| | - Marianna Feretzaki
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
| | - Joachim Lingner
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
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17
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San Martin-Alonso M, Soler-Oliva ME, García-Rubio M, García-Muse T, Aguilera A. Harmful R-loops are prevented via different cell cycle-specific mechanisms. Nat Commun 2021; 12:4451. [PMID: 34294712 PMCID: PMC8298424 DOI: 10.1038/s41467-021-24737-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 07/01/2021] [Indexed: 12/13/2022] Open
Abstract
Identifying how R-loops are generated is crucial to know how transcription compromises genome integrity. We show by genome-wide analysis of conditional yeast mutants that the THO transcription complex, prevents R-loop formation in G1 and S-phase, whereas the Sen1 DNA-RNA helicase prevents them only in S-phase. Interestingly, damage accumulates asymmetrically downstream of the replication fork in sen1 cells but symmetrically in the hpr1 THO mutant. Our results indicate that: R-loops form co-transcriptionally independently of DNA replication; that THO is a general and cell-cycle independent safeguard against R-loops, and that Sen1, in contrast to previously believed, is an S-phase-specific R-loop resolvase. These conclusions have important implications for the mechanism of R-loop formation and the role of other factors reported to affect on R-loop homeostasis.
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Affiliation(s)
- Marta San Martin-Alonso
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-UPO, Seville, Spain
| | - María E Soler-Oliva
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-UPO, Seville, Spain
| | - María García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-UPO, Seville, Spain
| | - Tatiana García-Muse
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-UPO, Seville, Spain.
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-UPO, Seville, Spain.
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18
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Palancade B, Rothstein R. The Ultimate (Mis)match: When DNA Meets RNA. Cells 2021; 10:cells10061433. [PMID: 34201169 PMCID: PMC8227541 DOI: 10.3390/cells10061433] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/04/2021] [Accepted: 06/05/2021] [Indexed: 12/20/2022] Open
Abstract
RNA-containing structures, including ribonucleotide insertions, DNA:RNA hybrids and R-loops, have recently emerged as critical players in the maintenance of genome integrity. Strikingly, different enzymatic activities classically involved in genome maintenance contribute to their generation, their processing into genotoxic or repair intermediates, or their removal. Here we review how this substrate promiscuity can account for the detrimental and beneficial impacts of RNA insertions during genome metabolism. We summarize how in vivo and in vitro experiments support the contribution of DNA polymerases and homologous recombination proteins in the formation of RNA-containing structures, and we discuss the role of DNA repair enzymes in their removal. The diversity of pathways that are thus affected by RNA insertions likely reflects the ancestral function of RNA molecules in genome maintenance and transmission.
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Affiliation(s)
- Benoit Palancade
- Institut Jacques Monod, Université de Paris, CNRS, F-75006 Paris, France
- Correspondence: (B.P.); (R.R.)
| | - Rodney Rothstein
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, USA
- Correspondence: (B.P.); (R.R.)
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19
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R-loops as Janus-faced modulators of DNA repair. Nat Cell Biol 2021; 23:305-313. [PMID: 33837288 DOI: 10.1038/s41556-021-00663-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/05/2021] [Indexed: 02/01/2023]
Abstract
R-loops are non-B DNA structures with intriguing dual consequences for gene expression and genome stability. In addition to their recognized roles in triggering DNA double-strand breaks (DSBs), R-loops have recently been demonstrated to accumulate in cis to DSBs, especially those induced in transcriptionally active loci. In this Review, we discuss whether R-loops actively participate in DSB repair or are detrimental by-products that must be removed to avoid genome instability.
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20
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Gómez-González B, Aguilera A. Origin matters: spontaneous DNA-RNA hybrids do not form in trans as a source of genome instability. Curr Genet 2020; 67:93-97. [PMID: 33095299 DOI: 10.1007/s00294-020-01117-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/07/2020] [Accepted: 10/10/2020] [Indexed: 12/30/2022]
Abstract
Multiple exogenous and endogenous genotoxic agents threaten the integrity of the genome, but one major source of spontaneous DNA damage is the formation of unscheduled DNA-RNA hybrids. These can be genetically detected by their ability to induce recombination. The origin of spontaneous hybrids has been mainly attributed to the nascent RNA formed co-transcriptionally in cis invading its own DNA template. However, it was unclear whether hybrids could also be spontaneously generated by RNA produced in a different locus (in trans). Using new genetic systems in the yeast Saccharomyces cerevisiae, we recently tested whether hybrids could be formed in trans and compromise genome integrity. Whereas we detected recombinogenic DNA-RNA hybrids in cis and in a Rad51-independent manner, we found no evidence for recombinogenic DNA-RNA hybrids to be formed with RNAs produced in trans. Here, we further discuss the implications in the field for the origin of genetic instability and the threats coming from RNAs.
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Affiliation(s)
- Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC, Seville, Spain.,Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC, Seville, Spain. .,Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain.
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