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Hourvitz N, Awad A, Tzfati Y. The many faces of the helicase RTEL1 at telomeres and beyond. Trends Cell Biol 2024; 34:109-121. [PMID: 37532653 DOI: 10.1016/j.tcb.2023.07.002] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/01/2023] [Accepted: 07/05/2023] [Indexed: 08/04/2023]
Abstract
Regulator of telomere elongation 1 (RTEL1) is known as a DNA helicase that is important for telomeres and genome integrity. However, the diverse phenotypes of RTEL1 dysfunction, the wide spectrum of symptoms caused by germline RTEL1 mutations, and the association of RTEL1 mutations with cancers suggest that RTEL1 is a complex machine that interacts with DNA, RNA, and proteins, and functions in diverse cellular pathways. We summarize the proposed functions of RTEL1 and discuss their implications for telomere maintenance. Studying RTEL1 is crucial for understanding the complex interplay between telomere maintenance and other nuclear pathways, and how compromising these pathways causes telomere biology diseases, various aging-associated pathologies, and cancer.
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Affiliation(s)
- Noa Hourvitz
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Jerusalem 91904, Israel
| | - Aya Awad
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Jerusalem 91904, Israel
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Jerusalem 91904, Israel.
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Hourvitz N, Kurolap A, Mory A, Haratz KK, Kidron D, Malinger G, Baris Feldman H, Yaron Y. SMARCC1 is a susceptibility gene for congenital hydrocephalus with an autosomal dominant inheritance mode and incomplete penetrance. Prenat Diagn 2023; 43:1374-1377. [PMID: 37639281 DOI: 10.1002/pd.6426] [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: 06/25/2023] [Revised: 08/10/2023] [Accepted: 08/13/2023] [Indexed: 08/29/2023]
Abstract
A Jewish couple of mixed origin was referred for genetic counseling following termination of pregnancy at 18 weeks of gestation due to severe ventriculomegaly with aqueduct stenosis. Trio exome sequencing revealed a loss-of-function heterozygous variant in the SMARCC1 gene inherited from an unaffected mother. The SMARCC1 gene is associated with embryonic neurodevelopmental processes. Recent studies have linked perturbations of the gene with autosomal dominant congenital hydrocephalus, albeit with reduced penetrance. However, these studies were not referenced in the SMARCC1 OMIM record (*601732) and the gene was not considered, at the time, an OMIM morbid gene. Following our case and appeal, SMARCC1 is now considered a susceptibility gene for hydrocephalus. This allowed us to reclassify the variant as likely pathogenic and empowered the couple to make informed reproductive choices.
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Affiliation(s)
- Noa Hourvitz
- The Genetics Institute and Genomics Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Alina Kurolap
- The Genetics Institute and Genomics Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Adi Mory
- The Genetics Institute and Genomics Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Karina Krajden Haratz
- Division of Ultrasound in Obstetrics and Gynecology, Lis Maternity and Hospital for Women's Health, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dvora Kidron
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Pathology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Gustavo Malinger
- Division of Ultrasound in Obstetrics and Gynecology, Lis Maternity and Hospital for Women's Health, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hagit Baris Feldman
- The Genetics Institute and Genomics Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yuval Yaron
- The Genetics Institute and Genomics Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Haj M, Levon A, Frey Y, Hourvitz N, Campisi J, Tzfati Y, Elkon R, Ziv Y, Shiloh Y. Accelerated replicative senescence of ataxia-telangiectasia skin fibroblasts is retained at physiologic oxygen levels, with unique and common transcriptional patterns. Aging Cell 2023; 22:e13869. [PMID: 37254625 PMCID: PMC10410012 DOI: 10.1111/acel.13869] [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: 11/28/2022] [Revised: 04/23/2023] [Accepted: 04/28/2023] [Indexed: 06/01/2023] Open
Abstract
The genetic disorder, ataxia-telangiectasia (A-T), is caused by loss of the homeostatic protein kinase, ATM, and combines genome instability, tissue degeneration, cancer predisposition, and premature aging. Primary fibroblasts from A-T patients exhibit premature senescence when grown at ambient oxygen concentration (21%). Here, we show that reducing oxygen concentration to a physiological level range (3%) dramatically extends the proliferative lifespan of human A-T skin fibroblasts. However, they still undergo senescence earlier than control cells grown under the same conditions and exhibit high genome instability. Comparative RNA-seq analysis of A-T and control fibroblasts cultured at 3% oxygen followed by cluster analysis of differentially expressed genes and functional enrichment analysis, revealed distinct transcriptional dynamics in A-T fibroblasts senescing in physiological oxygen concentration. While some transcriptional patterns were similar to those observed during replicative senescence of control cells, others were unique to the senescing A-T cells. We observed in them a robust activation of interferon-stimulated genes, with undetected expression the interferon genes themselves. This finding suggests an activation of a non-canonical cGAS-STING-mediated pathway, which presumably responds to cytosolic DNA emanating from extranuclear micronuclei detected in these cells. Senescing A-T fibroblasts also exhibited a marked, intriguely complex alteration in the expression of genes associated with extracellular matrix (ECM) remodeling. Notably, many of the induced ECM genes encode senescence-associated secretory phenotype (SASP) factors known for their paracrine pro-fibrotic effects. Our data provide a molecular dimension to the segmental premature aging observed in A-T patients and its associated symptoms, which develop as the patients advance in age.
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Affiliation(s)
- Majd Haj
- Department of Human Molecular Genetics and BiochemistryTel Aviv University School of MedicineTel AvivIsrael
| | - Amit Levon
- Department of Human Molecular Genetics and BiochemistryTel Aviv University School of MedicineTel AvivIsrael
| | - Yann Frey
- Department of Human Molecular Genetics and BiochemistryTel Aviv University School of MedicineTel AvivIsrael
| | - Noa Hourvitz
- The Alexander Silberman Institute of Life SciencesThe Hebrew University of JerusalemJerusalemIsrael
| | | | - Yehuda Tzfati
- The Alexander Silberman Institute of Life SciencesThe Hebrew University of JerusalemJerusalemIsrael
| | - Ran Elkon
- Department of Human Molecular Genetics and BiochemistryTel Aviv University School of MedicineTel AvivIsrael
| | - Yael Ziv
- Department of Human Molecular Genetics and BiochemistryTel Aviv University School of MedicineTel AvivIsrael
| | - Yosef Shiloh
- Department of Human Molecular Genetics and BiochemistryTel Aviv University School of MedicineTel AvivIsrael
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Hourvitz N. Small STEPs toward a big change. Cell 2023; 186:1092-1096. [PMID: 36931238 DOI: 10.1016/j.cell.2023.02.012] [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: 11/11/2022] [Revised: 12/29/2022] [Accepted: 02/08/2023] [Indexed: 03/18/2023]
Abstract
Noa Hourvitz is a graduate of the Science Training Encouraging Peace (STEP) program. The STEP Program funds pairs of Israeli and Palestinian students to study together for the length of their graduate degrees. She writes about the friendship she developed with her STEP partner and how science bridged political barriers.
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Affiliation(s)
- Noa Hourvitz
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel; The Genetics Institute and Genomic Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
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Awad A, Glousker G, Lamm N, Tawil S, Hourvitz N, Smoom R, Revy P, Tzfati Y. Full length RTEL1 is required for the elongation of the single-stranded telomeric overhang by telomerase. Nucleic Acids Res 2020; 48:7239-7251. [PMID: 32542379 PMCID: PMC7367169 DOI: 10.1093/nar/gkaa503] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 05/29/2020] [Accepted: 06/02/2020] [Indexed: 12/17/2022] Open
Abstract
Telomeres cap the ends of eukaryotic chromosomes and distinguish them from broken DNA ends to suppress DNA damage response, cell cycle arrest and genomic instability. Telomeres are elongated by telomerase to compensate for incomplete replication and nuclease degradation and to extend the proliferation potential of germ and stem cells and most cancers. However, telomeres in somatic cells gradually shorten with age, ultimately leading to cellular senescence. Hoyeraal-Hreidarsson syndrome (HHS) is characterized by accelerated telomere shortening and diverse symptoms including bone marrow failure, immunodeficiency, and neurodevelopmental defects. HHS is caused by germline mutations in telomerase subunits, factors essential for its biogenesis and recruitment to telomeres, and in the helicase RTEL1. While diverse phenotypes were associated with RTEL1 deficiency, the telomeric role of RTEL1 affected in HHS is yet unknown. Inducible ectopic expression of wild-type RTEL1 in patient fibroblasts rescued the cells, enabled telomerase-dependent telomere elongation and suppressed the abnormal cellular phenotypes, while silencing its expression resulted in gradual telomere shortening. Our observations reveal an essential role of the RTEL1 C-terminus in facilitating telomerase action at the telomeric 3′ overhang. Thus, the common etiology for HHS is the compromised telomerase action, resulting in telomere shortening and reduced lifespan of telomerase positive cells.
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Affiliation(s)
- Aya Awad
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Galina Glousker
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Noa Lamm
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Shadi Tawil
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Noa Hourvitz
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Riham Smoom
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer and Paris Descartes-Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
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