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Kannan A, Gangadharan Leela S, Branzei D, Gangwani L. Role of senataxin in R-loop-mediated neurodegeneration. Brain Commun 2024; 6:fcae239. [PMID: 39070547 PMCID: PMC11277865 DOI: 10.1093/braincomms/fcae239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 06/14/2024] [Accepted: 07/13/2024] [Indexed: 07/30/2024] Open
Abstract
Senataxin is an RNA:DNA helicase that plays an important role in the resolution of RNA:DNA hybrids (R-loops) formed during transcription. R-loops are involved in the regulation of biological processes such as immunoglobulin class switching, gene expression and DNA repair. Excessive accumulation of R-loops results in DNA damage and loss of genomic integrity. Senataxin is critical for maintaining optimal levels of R-loops to prevent DNA damage and acts as a genome guardian. Within the nucleus, senataxin interacts with various RNA processing factors and DNA damage response and repair proteins. Senataxin interactors include survival motor neuron and zinc finger protein 1, with whom it co-localizes in sub-nuclear bodies. Despite its ubiquitous expression, mutations in senataxin specifically affect neurons and result in distinct neurodegenerative diseases such as amyotrophic lateral sclerosis type 4 and ataxia with oculomotor apraxia type 2, which are attributed to the gain-of-function and the loss-of-function mutations in senataxin, respectively. In addition, low levels of senataxin (loss-of-function) in spinal muscular atrophy result in the accumulation of R-loops causing DNA damage and motor neuron degeneration. Senataxin may play multiple functions in diverse cellular processes; however, its emerging role in R-loop resolution and maintenance of genomic integrity is gaining attention in the field of neurodegenerative diseases. In this review, we highlight the role of senataxin in R-loop resolution and its potential as a therapeutic target to treat neurodegenerative diseases.
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Affiliation(s)
| | - Shyni Gangadharan Leela
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
| | - Dana Branzei
- The AIRC Institute of Molecular Oncology Foundation, IFOM ETS, Milan 20139, Italy
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia 27100, Italy
| | - Laxman Gangwani
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
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Lopergolo D, Rosini F, Pretegiani E, Bargagli A, Serchi V, Rufa A. Autosomal recessive cerebellar ataxias: a diagnostic classification approach according to ocular features. Front Integr Neurosci 2024; 17:1275794. [PMID: 38390227 PMCID: PMC10883068 DOI: 10.3389/fnint.2023.1275794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/10/2023] [Indexed: 02/24/2024] Open
Abstract
Autosomal recessive cerebellar ataxias (ARCAs) are a heterogeneous group of neurodegenerative disorders affecting primarily the cerebellum and/or its afferent tracts, often accompanied by damage of other neurological or extra-neurological systems. Due to the overlap of clinical presentation among ARCAs and the variety of hereditary, acquired, and reversible etiologies that can determine cerebellar dysfunction, the differential diagnosis is challenging, but also urgent considering the ongoing development of promising target therapies. The examination of afferent and efferent visual system may provide neurophysiological and structural information related to cerebellar dysfunction and neurodegeneration thus allowing a possible diagnostic classification approach according to ocular features. While optic coherence tomography (OCT) is applied for the parametrization of the optic nerve and macular area, the eye movements analysis relies on a wide range of eye-tracker devices and the application of machine-learning techniques. We discuss the results of clinical and eye-tracking oculomotor examination, the OCT findings and some advancing of computer science in ARCAs thus providing evidence sustaining the identification of robust eye parameters as possible markers of ARCAs.
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Affiliation(s)
- Diego Lopergolo
- Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- UOC Neurologia e Malattie Neurometaboliche, Azienda Ospedaliero-Universitaria Senese, Siena, Italy
| | - Francesca Rosini
- UOC Stroke Unit, Department of Emergenza-Urgenza, Azienda Ospedaliero-Universitaria Senese, Siena, Italy
| | - Elena Pretegiani
- Unit of Neurology, Centre Hospitalier Universitaire Vaudoise Lausanne, Unit of Neurology and Cognitive Neurorehabilitation, Universitary Hospital of Fribourg, Fribourg, Switzerland
| | - Alessia Bargagli
- Evalab-Neurosense, Department of Medicine Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Valeria Serchi
- Evalab-Neurosense, Department of Medicine Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Alessandra Rufa
- Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- UOC Neurologia e Malattie Neurometaboliche, Azienda Ospedaliero-Universitaria Senese, Siena, Italy
- Evalab-Neurosense, Department of Medicine Surgery and Neuroscience, University of Siena, Siena, Italy
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3
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Tsui A, Kouznetsova VL, Kesari S, Fiala M, Tsigelny IF. Role of Senataxin in Amyotrophic Lateral Sclerosis. J Mol Neurosci 2023; 73:996-1009. [PMID: 37982993 DOI: 10.1007/s12031-023-02169-0] [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] [Received: 09/05/2023] [Accepted: 10/23/2023] [Indexed: 11/21/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive, uncurable neurodegenerative disorder characterized by the degradation of motor neurons leading to muscle impairment, failure, and death. Senataxin, encoded by the SETX gene, is a human helicase protein whose mutations have been linked with ALS onset, particularly in its juvenile ALS4 form. Using senataxin's yeast homolog Sen1 as a model for study, it is suggested that senataxin's N-terminus interacts with RNA polymerase II, whilst its C-terminus engages in helicase activity. Senataxin is heavily involved in transcription regulation, termination, and R-loop resolution, enabled by recruitment and interactions with enzymes such as ubiquitin protein ligase SAN1 and ribonuclease H (RNase H). Senataxin also engages in DNA damage response (DDR), primarily interacting with the exosome subunit Rrp45. The Sen1 mutation E1597K, alongside the L389S and R2136H gain-of-function mutations to senataxin, is shown to cause negative structural and thus functional effects to the protein, thus contributing to a disruption in WT functions, motor neuron (MN) degeneration, and the manifestation of ALS clinical symptoms. This review corroborates and summarizes published papers concerning the structure and function of senataxin as well as the effects of their mutations in ALS pathology in order to compile current knowledge and provide a reference for future research. The findings compiled in this review are indicative of the experimental and therapeutic potential of senataxin and its mutations as a target in future ALS treatment/cure discovery, with some potential therapeutic routes also being discussed in the review.
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Affiliation(s)
- Andrew Tsui
- REHS Program, San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA
| | - Valentina L Kouznetsova
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA
- CureScience Institute, San Diego, CA, USA
- BiAna, San Diego, La Jolla, CA, USA
| | | | - Milan Fiala
- Department of Integrative Biology and Physiology, School of Medicine, UCLA, Los Angeles, CA, USA
| | - Igor F Tsigelny
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA, USA.
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.
- CureScience Institute, San Diego, CA, USA.
- BiAna, San Diego, La Jolla, CA, USA.
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Bennett CL, Dastidar S, Arnold FJ, McKinstry SU, Stockford C, Freibaum BD, Sopher BL, Wu M, Seidner G, Joiner W, Taylor JP, West RJH, La Spada AR. Senataxin helicase, the causal gene defect in ALS4, is a significant modifier of C9orf72 ALS G4C2 and arginine-containing dipeptide repeat toxicity. Acta Neuropathol Commun 2023; 11:164. [PMID: 37845749 PMCID: PMC10580588 DOI: 10.1186/s40478-023-01665-z] [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: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/18/2023] Open
Abstract
Identifying genetic modifiers of familial amyotrophic lateral sclerosis (ALS) may reveal targets for therapeutic modulation with potential application to sporadic ALS. GGGGCC (G4C2) repeat expansions in the C9orf72 gene underlie the most common form of familial ALS, and generate toxic arginine-containing dipeptide repeats (DPRs), which interfere with membraneless organelles, such as the nucleolus. Here we considered senataxin (SETX), the genetic cause of ALS4, as a modifier of C9orf72 ALS, because SETX is a nuclear helicase that may regulate RNA-protein interactions involved in ALS dysfunction. After documenting that decreased SETX expression enhances arginine-containing DPR toxicity and C9orf72 repeat expansion toxicity in HEK293 cells and primary neurons, we generated SETX fly lines and evaluated the effect of SETX in flies expressing either (G4C2)58 repeats or glycine-arginine-50 [GR(50)] DPRs. We observed dramatic suppression of disease phenotypes in (G4C2)58 and GR(50) Drosophila models, and detected a striking relocalization of GR(50) out of the nucleolus in flies co-expressing SETX. Next-generation GR(1000) fly models, that show age-related motor deficits in climbing and movement assays, were similarly rescued with SETX co-expression. We noted that the physical interaction between SETX and arginine-containing DPRs is partially RNA-dependent. Finally, we directly assessed the nucleolus in cells expressing GR-DPRs, confirmed reduced mobility of proteins trafficking to the nucleolus upon GR-DPR expression, and found that SETX dosage modulated nucleolus liquidity in GR-DPR-expressing cells and motor neurons. These findings reveal a hitherto unknown connection between SETX function and cellular processes contributing to neuron demise in the most common form of familial ALS.
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Affiliation(s)
- Craig L Bennett
- Departments of Pathology, Laboratory Medicine, Neurology, and Biological Chemistry, UCI Center for Neurotherapeutics, University of California Irvine School of Medicine, Irvine, CA, 92697, USA
- Department of Neurology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Somasish Dastidar
- Department of Neurology, Duke University School of Medicine, Durham, NC, 27710, USA
- Center for Molecular Neurosciences, Kasturba Medical College, Manipal, 576104, India
| | - Frederick J Arnold
- Departments of Pathology, Laboratory Medicine, Neurology, and Biological Chemistry, UCI Center for Neurotherapeutics, University of California Irvine School of Medicine, Irvine, CA, 92697, USA
| | - Spencer U McKinstry
- Department of Neurology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Cameron Stockford
- Departments of Pathology, Laboratory Medicine, Neurology, and Biological Chemistry, UCI Center for Neurotherapeutics, University of California Irvine School of Medicine, Irvine, CA, 92697, USA
| | - Brian D Freibaum
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Bryce L Sopher
- Department of Laboratory Medicine and Pathology, University of Washington Medical Center, Seattle, WA, 98195, USA
| | - Meilin Wu
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Glen Seidner
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, 92093, USA
| | - William Joiner
- Department of Laboratory Medicine and Pathology, University of Washington Medical Center, Seattle, WA, 98195, USA
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, 20815, USA
| | - Ryan J H West
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, S10 2HQ, UK.
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK.
| | - Albert R La Spada
- Departments of Pathology, Laboratory Medicine, Neurology, and Biological Chemistry, UCI Center for Neurotherapeutics, University of California Irvine School of Medicine, Irvine, CA, 92697, USA.
- Department of Neurology, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Neurobiology and Behavior, University of California Irvine School of Biosciences, Irvine, CA, 92697, USA.
- UCI Center for Neurotherapeutics, University of California Irvine, Irvine, CA, 92697, USA.
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Cheng X, Yang W, Lin W, Mei F. Paradoxes of Cellular SUMOylation Regulation: A Role of Biomolecular Condensates? Pharmacol Rev 2023; 75:979-1006. [PMID: 37137717 PMCID: PMC10441629 DOI: 10.1124/pharmrev.122.000784] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 05/05/2023] Open
Abstract
Protein SUMOylation is a major post-translational modification essential for maintaining cellular homeostasis. SUMOylation has long been associated with stress responses as a diverse array of cellular stress signals are known to trigger rapid alternations in global protein SUMOylation. In addition, while there are large families of ubiquitination enzymes, all small ubiquitin-like modifiers (SUMOs) are conjugated by a set of enzymatic machinery comprising one heterodimeric SUMO-activating enzyme, a single SUMO-conjugating enzyme, and a small number of SUMO protein ligases and SUMO-specific proteases. How a few SUMOylation enzymes specifically modify thousands of functional targets in response to diverse cellular stresses remains an enigma. Here we review recent progress toward understanding the mechanisms of SUMO regulation, particularly the potential roles of liquid-liquid phase separation/biomolecular condensates in regulating cellular SUMOylation during cellular stresses. In addition, we discuss the role of protein SUMOylation in pathogenesis and the development of novel therapeutics targeting SUMOylation. SIGNIFICANCE STATEMENT: Protein SUMOylation is one of the most prevalent post-translational modifications and plays a vital role in maintaining cellular homeostasis in response to stresses. Protein SUMOylation has been implicated in human pathogenesis, such as cancer, cardiovascular diseases, neurodegeneration, and infection. After more than a quarter century of extensive research, intriguing enigmas remain regarding the mechanism of cellular SUMOylation regulation and the therapeutic potential of targeting SUMOylation.
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Affiliation(s)
- Xiaodong Cheng
- Department of Integrative Biology & Pharmacology and Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Wenli Yang
- Department of Integrative Biology & Pharmacology and Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Wei Lin
- Department of Integrative Biology & Pharmacology and Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Fang Mei
- Department of Integrative Biology & Pharmacology and Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
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Templeton CW, Laimins LA. p53-dependent R-loop formation and HPV pathogenesis. Proc Natl Acad Sci U S A 2023; 120:e2305907120. [PMID: 37611058 PMCID: PMC10467572 DOI: 10.1073/pnas.2305907120] [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: 04/12/2023] [Accepted: 06/30/2023] [Indexed: 08/25/2023] Open
Abstract
R-loops are trimeric RNA: DNA hybrids that are important physiological regulators of transcription; however, their aberrant formation or turnover leads to genomic instability and DNA breaks. High-risk human papillomaviruses (HPV) are the causative agents of genital as well as oropharyngeal cancers and exhibit enhanced amounts of DNA breaks. The levels of R-loops were found to be increased up to 50-fold in cells that maintain high-risk HPV genomes and were readily detected in squamous cell cervical carcinomas in vivo but not in normal cells. The high levels of R-loops in HPV-positive cells were present on both viral and cellular sites together with RNase H1, an enzyme that controls their resolution. Depletion of RNase H1 in HPV-positive cells further increased R-loop levels, resulting in impaired viral transcription and replication along with reduced expression of the DNA repair genes such as FANCD2 and ATR, both of which are necessary for viral functions. Overexpression of RNase H1 decreased total R-loop levels, resulting in a reduction of DNA breaks by over 50%. Furthermore, increased RNase H1 expression blocked viral transcription and replication while enhancing the expression of factors in the innate immune regulatory pathway. This suggests that maintaining elevated R-loop levels is important for the HPV life cycle. The E6 viral oncoprotein was found to be responsible for inducing high levels of R-loops by inhibiting p53's transcriptional activity. Our studies indicate that high R-loop levels are critical for HPV pathogenesis and that this depends on suppressing the p53 pathway.
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Affiliation(s)
- Conor Winslow Templeton
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Laimonis A. Laimins
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
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Gatti V, De Domenico S, Melino G, Peschiaroli A. Senataxin and R-loops homeostasis: multifaced implications in carcinogenesis. Cell Death Discov 2023; 9:145. [PMID: 37147318 PMCID: PMC10163015 DOI: 10.1038/s41420-023-01441-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/06/2023] [Accepted: 04/20/2023] [Indexed: 05/07/2023] Open
Abstract
R-loops are inherent byproducts of transcription consisting of an RNA:DNA hybrid and a displaced single-stranded DNA. These structures are of key importance in controlling numerous physiological processes and their homeostasis is tightly controlled by the activities of several enzymes deputed to process R-loops and prevent their unproper accumulation. Senataxin (SETX) is an RNA/DNA helicase which catalyzes the unwinding of RNA:DNA hybrid portion of the R-loops, promoting thus their resolution. The key importance of SETX in R-loops homeostasis and its relevance with pathophysiological events is highlighted by the evidence that gain or loss of function SETX mutations underlie the pathogenesis of two distinct neurological disorders. Here, we aim to describe the potential impact of SETX on tumor onset and progression, trying to emphasize how dysregulation of this enzyme observed in human tumors might impact tumorigenesis. To this aim, we will describe the functional relevance of SETX in regulating gene expression, genome integrity, and inflammation response and discuss how cancer-associated SETX mutations might affect these pathways, contributing thus to tumor development.
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Affiliation(s)
- Veronica Gatti
- National Research Council of Italy, Institute of Translational Pharmacology, Rome, Italy
| | - Sara De Domenico
- Department of Experimental Medicine, TOR, University of Rome Tor Vergata, Rome, Italy
| | - Gerry Melino
- Department of Experimental Medicine, TOR, University of Rome Tor Vergata, Rome, Italy
| | - Angelo Peschiaroli
- National Research Council of Italy, Institute of Translational Pharmacology, Rome, Italy.
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Kassouf T, Shrivastava R, Meszka I, Bailly A, Polanowska J, Trauchessec H, Mandrioli J, Carra S, Xirodimas DP. Targeting the NEDP1 enzyme to ameliorate ALS phenotypes through stress granule disassembly. SCIENCE ADVANCES 2023; 9:eabq7585. [PMID: 37000881 PMCID: PMC10065448 DOI: 10.1126/sciadv.abq7585] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 02/27/2023] [Indexed: 06/19/2023]
Abstract
The elimination of aberrant inclusions is regarded as a therapeutic approach in neurodegeneration. In amyotrophic lateral sclerosis (ALS), mutations in proteins found within cytoplasmic condensates called stress granules (SGs) are linked to the formation of pathological SGs, aberrant protein inclusions, and neuronal toxicity. We found that inhibition of NEDP1, the enzyme that processes/deconjugates the ubiquitin-like molecule NEDD8, promotes the disassembly of physiological and pathological SGs. Reduction in poly(ADP-ribose) polymerase1 activity through hyper-NEDDylation is a key mechanism for the observed phenotype. These effects are related to improved cell survival in human cells, and in C. elegans, nedp1 deletion ameliorates ALS phenotypes related to animal motility. Our studies reveal NEDP1 as potential therapeutic target for ALS, correlated to the disassembly of pathological SGs.
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Affiliation(s)
| | | | - Igor Meszka
- CRBM, Univ. Montpellier, CNRS, Montpellier, France
| | | | | | | | - Jessica Mandrioli
- Neurology Unit, Azienda Ospedaliero Universitaria di Modena, 41126 Modena, Italy
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia,G. Campi 287, 41125 Modena, Italy
| | - Serena Carra
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia,G. Campi 287, 41125 Modena, Italy
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The Phosphorylated Form of the Histone H2AX (γH2AX) in the Brain from Embryonic Life to Old Age. Molecules 2021; 26:molecules26237198. [PMID: 34885784 PMCID: PMC8659122 DOI: 10.3390/molecules26237198] [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: 10/26/2021] [Revised: 11/25/2021] [Accepted: 11/25/2021] [Indexed: 12/12/2022] Open
Abstract
The γ phosphorylated form of the histone H2AX (γH2AX) was described more than 40 years ago and it was demonstrated that phosphorylation of H2AX was one of the first cellular responses to DNA damage. Since then, γH2AX has been implicated in diverse cellular functions in normal and pathological cells. In the first part of this review, we will briefly describe the intervention of H2AX in the DNA damage response (DDR) and its role in some pivotal cellular events, such as regulation of cell cycle checkpoints, genomic instability, cell growth, mitosis, embryogenesis, and apoptosis. Then, in the main part of this contribution, we will discuss the involvement of γH2AX in the normal and pathological central nervous system, with particular attention to the differences in the DDR between immature and mature neurons, and to the significance of H2AX phosphorylation in neurogenesis and neuronal cell death. The emerging picture is that H2AX is a pleiotropic molecule with an array of yet not fully understood functions in the brain, from embryonic life to old age.
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