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Exploring the Origin and Physiological Significance of DNA Double Strand Breaks in the Developing Neuroretina. Int J Mol Sci 2022; 23:ijms23126449. [PMID: 35742893 PMCID: PMC9224223 DOI: 10.3390/ijms23126449] [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: 05/14/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 02/04/2023] Open
Abstract
Genetic mosaicism is an intriguing physiological feature of the mammalian brain that generates altered genetic information and provides cellular, and prospectively functional, diversity in a manner similar to that of the immune system. However, both its origin and its physiological significance remain poorly characterized. Most, if not all, cases of somatic mosaicism require prior generation and repair of DNA double strand breaks (DSBs). The relationship between DSB generation, neurogenesis, and early neuronal cell death revealed by our studies in the developing retina provides new perspectives on the different mechanisms that contribute to DNA rearrangements in the developing brain. Here, we speculate on the physiological significance of these findings.
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Frizinsky S, Rechavi E, Barel O, Lee YN, Simon AJ, Lev A, Stauber T, Adam E, Somech R. Novel NHEJ1 pathogenic variant linked to severe combined immunodeficiency, microcephaly, and abnormal T and B cell receptor repertoires. Front Pediatr 2022; 10:883173. [PMID: 35967585 PMCID: PMC9363661 DOI: 10.3389/fped.2022.883173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/22/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND During the process of generating diverse T and B cell receptor (TCR and BCR, respectively) repertoires, double-strand DNA breaks are produced. Subsequently, these breaks are corrected by a complex system led by the non-homologous end-joining (NHEJ). Pathogenic variants in genes involved in this process, such as the NHEJ1 gene, cause severe combined immunodeficiency syndrome (SCID) along with neurodevelopmental disease and sensitivity to ionizing radiation. OBJECTIVE To provide new clinical and immunological insights on NHEJ1 deficiency arising from a newly diagnosed patient with severe immunodeficiency. MATERIALS AND METHODS A male infant, born to consanguineous parents, suspected of having primary immunodeficiency underwent immunological and genetic workup. This included a thorough assessment of T cell phenotyping and lymphocyte activation by mitogen stimulation tests, whole-exome sequencing (WES), TCR repertoire Vβ repertoire via flow cytometry analysis, and TCR and BCR repertoire analysis via next-generation sequencing (NGS). RESULTS Clinical findings included microcephaly, recurrent pneumonia, and failure to thrive. An immune workup revealed lymphopenia, reduced T cell function, and hypogammaglobulinemia. Skewed TCR Vβ repertoire, TCR gamma (TRG) repertoire, and BCR repertoire were determined in the patient. Genetic analysis identified a novel homozygous missense pathogenic variant in XLF/Cernunnos: c.A580Ins.T; p.M194fs. The patient underwent a successful hematopoietic stem cell transplantation (HSCT). CONCLUSION A novel NHEJ1 pathogenic variant is reported in a patient who presented with SCID phenotype that displayed clonally expanded T and B cells. An adjusted HSCT was safe to ensure full T cell immune reconstitution.
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Affiliation(s)
- Shirly Frizinsky
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Erez Rechavi
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ortal Barel
- The Wohl Institute for Translational Medicine and Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Yu Nee Lee
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,The Wohl Institute for Translational Medicine and Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Amos J Simon
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,The Wohl Institute for Translational Medicine and Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Atar Lev
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,The Wohl Institute for Translational Medicine and Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Tali Stauber
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,The Wohl Institute for Translational Medicine and Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
| | - Etai Adam
- Department of Pediatric Hematology, Oncology and Bone Marrow Transplant, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel
| | - Raz Somech
- Pediatric Department A and the Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,The Wohl Institute for Translational Medicine and Cancer Research Center, Sheba Medical Center, Ramat Gan, Israel
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Molecular characterization of a 1p36 chromosomal duplication and in utero interference define ENO1 as a candidate gene for polymicrogyria. Eur J Hum Genet 2020; 28:1703-1713. [PMID: 32488097 DOI: 10.1038/s41431-020-0659-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 05/12/2020] [Accepted: 05/19/2020] [Indexed: 11/08/2022] Open
Abstract
While chromosome 1p36 deletion syndrome is one of the most common terminal subtelomeric microdeletion syndrome, 1p36 microduplications are rare events. Polymicrogyria (PMG) is a brain malformation phenotype frequently present in patients with 1p36 monosomy. The gene whose haploinsufficiency could cause this phenotype remains to be identified. We used high-resolution arrayCGH in patients with various forms of PMG in order to identify chromosomal variants associated to the malformation and characterized the genes included in these regions in vitro and in vivo. We identified the smallest case of 1p36 duplication reported to date in a patient presenting intellectual disability, microcephaly, epilepsy, and perisylvian polymicrogyria. The duplicated segment is intrachromosomal, duplicated in mirror and contains two genes: enolase 1 (ENO1) and RERE, both disrupted by the rearrangement. Gene expression analysis performed using the patient cells revealed a reduced expression, mimicking haploinsufficiency. We performed in situ hybridization to describe the developmental expression profile of the two genes in mouse development. In addition, we used in utero electroporation of shRNAs to show that Eno1 inactivation in the rat causes a brain development defect. These experiments allowed us to define the ENO1 gene as the most likely candidate to contribute to the brain malformation phenotype of the studied patient and consequently a candidate to contribute to the malformations of the cerebral cortex observed in patients with 1p36 monosomy.
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Álvarez-Lindo N, Baleriola J, de Los Ríos V, Suárez T, de la Rosa EJ. RAG-2 deficiency results in fewer phosphorylated histone H2AX foci, but increased retinal ganglion cell death and altered axonal growth. Sci Rep 2019; 9:18486. [PMID: 31811168 PMCID: PMC6898044 DOI: 10.1038/s41598-019-54873-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023] Open
Abstract
DNA double-strand breaks (DSBs), selectively visualized as γ-H2AX+ foci, occur during the development of the central nervous system, including the retina, although their origin and biological significance are poorly understood. Mutant mice with DSB repair mechanism defects exhibit increased numbers of γ-H2AX+ foci, increased cell death during neural development, and alterations in axonogenesis in the embryonic retina. The aim of this study was to identify putative sources of DSBs. One of the identified DSBs sources is LINE-1 retrotransposition. While we did not detect changes in LINE-1 DNA content during the early period of cell death associated with retinal neurogenesis, retinal development was altered in mice lacking RAG-2, a component of the RAG-1,2-complex responsible for initiating somatic recombination in lymphocytes. Although γ-H2AX+ foci were less abundant in the rag2−/− mouse retina, retinal ganglion cell death was increased and axonal growth and navigation were impaired in the RAG-2 deficient mice, a phenotype shared with mutant mice with defective DNA repair mechanisms. These findings demonstrate that RAG-2 is necessary for proper retinal development, and suggest that both DSB generation and repair are genuine processes intrinsic to neural development.
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Affiliation(s)
- Noemí Álvarez-Lindo
- 3D Lab: Development, Differentiation & Degeneration, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CIB/CSIC), Madrid, Spain
| | - Jimena Baleriola
- 3D Lab: Development, Differentiation & Degeneration, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CIB/CSIC), Madrid, Spain.,Laboratory of local translation in neurons and glia, Achucarro Basque Center for Neuroscience; Department of Cell Biology and Histology, University of the Basque Country, Leioa; and Ikerbasque Foundation, Bilbao, Bizkaia, Spain
| | - Vivian de Los Ríos
- Proteomics and Genomics, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CIB/CSIC), Madrid, Spain
| | - Teresa Suárez
- 3D Lab: Development, Differentiation & Degeneration, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CIB/CSIC), Madrid, Spain
| | - Enrique J de la Rosa
- 3D Lab: Development, Differentiation & Degeneration, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CIB/CSIC), Madrid, Spain.
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Esmaeilzadeh H, Bordbar MR, Hojaji Z, Habibzadeh P, Afshinfar D, Miryounesi M, Fardaei M, Faghihi MA. An immunocompetent patient with a nonsense mutation in NHEJ1 gene. BMC MEDICAL GENETICS 2019; 20:45. [PMID: 30898087 PMCID: PMC6429708 DOI: 10.1186/s12881-019-0784-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 03/13/2019] [Indexed: 11/10/2022]
Abstract
BACKGROUND DNA double-strand breaks (DSBs) are among the most deleterious types of DNA damage. DSBs are repaired by homologous recombination or non-homologous end-joining (NHEJ). NHEJ, which is central to the process of V(D)J recombination is the principle pathway for DSB repair in higher eukaryotes. Mutations in NHEJ1 gene have been associated with severe combined immunodeficiency. CASE PRESENTATION The patient was a 3.5-year-old girl, a product of consanguineous first-degree cousin marriage, who was homozygous for a nonsense mutation in NHEJ1 gene. She had initially presented with failure to thrive, proportional microcephaly as well as autoimmune hemolytic anemia (AIHA), which responded well to treatment with prednisolone. However, the patient was immunocompetent despite having this pathogenic mutation. CONCLUSIONS Herein, we report on a patient who was clinically immunocompetent despite having a pathogenic mutation in NHEJ1 gene. Our findings provided evidence for the importance of other end-joining auxiliary pathways that would function in maintaining genetic stability. Clinicians should therefore be aware that pathogenic mutations in NHEJ pathway are not necessarily associated with clinical immunodeficiency.
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Affiliation(s)
- Hossein Esmaeilzadeh
- Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Allergy and Clinical Immunology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | - Zahra Hojaji
- Department of Allergy and Clinical Immunology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Parham Habibzadeh
- Persian BayanGene Research and Training Center, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Dorna Afshinfar
- Persian BayanGene Research and Training Center, Shiraz, Iran
| | - Mohammad Miryounesi
- Genomic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Majid Fardaei
- Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Medical Genetics, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ali Faghihi
- Persian BayanGene Research and Training Center, Shiraz, Iran. .,Center for Therapeutic Innovation, Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, USA.
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El Waly B, Cayre M, Durbec P. Promoting Myelin Repair through In Vivo Neuroblast Reprogramming. Stem Cell Reports 2018; 10:1492-1504. [PMID: 29606615 PMCID: PMC5995160 DOI: 10.1016/j.stemcr.2018.02.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/26/2018] [Accepted: 02/28/2018] [Indexed: 11/28/2022] Open
Abstract
Demyelination is frequently observed in a variety of CNS insults and neurodegenerative diseases. In rodents, adult neural stem cells can generate oligodendrocytes and participate to myelin repair. However, these cells mainly produce migratory neuroblasts that differentiate in the olfactory bulb. Here, we show that, in the demyelination context, a small subset of these neuroblasts can spontaneously convert into myelinating oligodendrocytes. Furthermore, we demonstrate that the contribution of neuroblasts to myelin repair can be improved by in vivo forced expression of two transcription factors: OLIG2 and SOX10. These factors promote directed fate conversion of endogenous subventricular zone neuroblasts into mature functional oligodendrocytes, leading to enhanced remyelination in a cuprizone-induced mouse model of demyelination. These findings highlight the unexpected plasticity of committed neuroblasts and provide proof of concept that they could be targeted for the treatment of demyelinated lesions in the adult brain. Sox10 and Olig2 convert endogenous neuroblasts into myelinating oligodendrocytes Converted cells migrate to the corpus callosum, striatum, and cortex Converted cells produce myelin and participate to the formation of node of Ranvier Forced neuroblast conversion improves myelin regeneration
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Affiliation(s)
- Bilal El Waly
- 1-Aix Marseille University, CNRS, IBDM-UMR 7288, Case 907, Parc Scientifique de Luminy, campus de Luminy, 13288 Marseille, Cedex 09, France
| | - Myriam Cayre
- 1-Aix Marseille University, CNRS, IBDM-UMR 7288, Case 907, Parc Scientifique de Luminy, campus de Luminy, 13288 Marseille, Cedex 09, France
| | - Pascale Durbec
- 1-Aix Marseille University, CNRS, IBDM-UMR 7288, Case 907, Parc Scientifique de Luminy, campus de Luminy, 13288 Marseille, Cedex 09, France.
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Increased neuronal death and disturbed axonal growth in the Polμ-deficient mouse embryonic retina. Sci Rep 2016; 6:25928. [PMID: 27172884 PMCID: PMC4865816 DOI: 10.1038/srep25928] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/25/2016] [Indexed: 01/04/2023] Open
Abstract
Programmed cell death occurs naturally at different stages of neural development, including neurogenesis. The functional role of this early phase of neural cell death, which affects recently differentiated neurons among other cell types, remains undefined. Some mouse models defective in DNA double-strand break (DSB) repair present massive cell death during neural development, occasionally provoking embryonic lethality, while other organs and tissues remain unaffected. This suggests that DSBs occur frequently and selectively in the developing nervous system. We analyzed the embryonic retina of a mouse model deficient in the error-prone DNA polymerase μ (Polμ), a key component of the non-homologous end-joining (NHEJ) repair system. DNA DSBs were increased in the mutant mouse at embryonic day 13.5 (E13.5), as well as the incidence of cell death that affected young neurons, including retinal ganglion cells (RGCs). Polμ(-/-) mice also showed disturbed RGC axonal growth and navigation, and altered distribution of the axonal guidance molecules L1-CAM and Bravo (also known as Nr-CAM). These findings demonstrate that Polμ is necessary for proper retinal development, and support that the generation of DSBs and their repair via the NHEJ pathway are genuine processes involved in neural development.
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