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Kate WD, Fanta M, Weinfeld M. Loss of the DNA repair protein, polynucleotide kinase/phosphatase, activates the type 1 interferon response independent of ionizing radiation. Nucleic Acids Res 2024:gkae654. [PMID: 39087523 DOI: 10.1093/nar/gkae654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 06/07/2024] [Accepted: 07/12/2024] [Indexed: 08/02/2024] Open
Abstract
DNA damage has been implicated in the stimulation of the type 1 interferon (T1IFN) response. Here, we show that downregulation of the DNA repair protein, polynucleotide kinase/phosphatase (PNKP), in a variety of cell lines causes robust phosphorylation of STAT1, upregulation of interferon-stimulated genes and persistent accumulation of cytosolic DNA, all of which are indicators for the activation of the T1IFN response. Furthermore, this did not require damage induction by ionizing radiation. Instead, our data revealed that production of reactive oxygen species (ROS) synergises with PNKP loss to potentiate the T1IFN response, and that loss of PNKP significantly compromises mitochondrial DNA (mtDNA) integrity. Depletion of mtDNA or treatment of PNKP-depleted cells with ROS scavengers abrogated the T1IFN response, implicating mtDNA as a significant source of the cytosolic DNA required to potentiate the T1IFN response. The STING signalling pathway is responsible for the observed increase in the pro-inflammatory gene signature in PNKP-depleted cells. While the response was dependent on ZBP1, cGAS only contributed to the response in some cell lines. Our data have implications for cancer therapy, since PNKP inhibitors would have the potential to stimulate the immune response, and also to the neurological disorders associated with PNKP mutation.
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Affiliation(s)
- Wisdom Deebeke Kate
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Mesfin Fanta
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Michael Weinfeld
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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Elkhateeb N, Issa MY, Elbendary HM, Elnaggar W, Ramadan A, Rafat K, Kamel M, Abdel-Ghafar SF, Amer F, Hassaan HM, Trunzo R, Pereira C, Abdel-Hamid MS, D'Arco F, Bauer P, Bertoli-Avella AM, Girgis M, Gleeson JG, Zaki MS, Selim L. The clinical and genetic landscape of developmental and epileptic encephalopathies in Egyptian children. Clin Genet 2024; 105:510-522. [PMID: 38221827 DOI: 10.1111/cge.14481] [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: 10/24/2023] [Revised: 12/28/2023] [Accepted: 01/03/2024] [Indexed: 01/16/2024]
Abstract
Developmental and epileptic encephalopathies (DEEs) are a heterogeneous group of epilepsies characterized by early-onset, refractory seizures associated with developmental regression or impairment, with a heterogeneous genetic landscape including genes implicated in various pathways and mechanisms. We retrospectively studied the clinical and genetic data of patients with genetic DEE who presented at two tertiary centers in Egypt over a 10-year period. Exome sequencing was used for genetic testing. We report 74 patients from 63 unrelated Egyptian families, with a high rate of consanguinity (58%). The most common seizure type was generalized tonic-clonic (58%) and multiple seizure types were common (55%). The most common epilepsy syndrome was early infantile DEE (50%). All patients showed variable degrees of developmental impairment. Microcephaly, hypotonia, ophthalmological involvement and neuroimaging abnormalities were common. Eighteen novel variants were identified and the phenotypes of five DEE genes were expanded with novel phenotype-genotype associations. Obtaining a genetic diagnosis had implications on epilepsy management in 17 patients with variants in 12 genes. In this study, we expand the phenotype and genotype spectrum of DEE in a large single ethnic cohort of patients. Reaching a genetic diagnosis guided precision management of epilepsy in a significant proportion of patients.
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Affiliation(s)
- Nour Elkhateeb
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Mahmoud Y Issa
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Hasnaa M Elbendary
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Walaa Elnaggar
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Areef Ramadan
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Karima Rafat
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Mona Kamel
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Sherif F Abdel-Ghafar
- Department of Medical Molecular Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Fawzia Amer
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Hebatallah M Hassaan
- Department of Pediatrics, Clinical Genetics Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | | | | | - Mohamed S Abdel-Hamid
- Department of Medical Molecular Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Felice D'Arco
- Radiology Department, Great Ormond Street Hospital for Children, London, UK
| | | | | | - Marian Girgis
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Joseph G Gleeson
- Department of Neurosciences, University of California, San Diego, La Jolla, USA
- Rady Children's Hospital, Rady Children's Institute for Genomic Medicine, San Diego, La Jolla, USA
| | - Maha S Zaki
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Laila Selim
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
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Ribeiro JH, Altinisik N, Rajan N, Verslegers M, Baatout S, Gopalakrishnan J, Quintens R. DNA damage and repair: underlying mechanisms leading to microcephaly. Front Cell Dev Biol 2023; 11:1268565. [PMID: 37881689 PMCID: PMC10597653 DOI: 10.3389/fcell.2023.1268565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/25/2023] [Indexed: 10/27/2023] Open
Abstract
DNA-damaging agents and endogenous DNA damage constantly harm genome integrity. Under genotoxic stress conditions, the DNA damage response (DDR) machinery is crucial in repairing lesions and preventing mutations in the basic structure of the DNA. Different repair pathways are implicated in the resolution of such lesions. For instance, the non-homologous DNA end joining and homologous recombination pathways are central cellular mechanisms by which eukaryotic cells maintain genome integrity. However, defects in these pathways are often associated with neurological disorders, indicating the pivotal role of DDR in normal brain development. Moreover, the brain is the most sensitive organ affected by DNA-damaging agents compared to other tissues during the prenatal period. The accumulation of lesions is believed to induce cell death, reduce proliferation and premature differentiation of neural stem and progenitor cells, and reduce brain size (microcephaly). Microcephaly is mainly caused by genetic mutations, especially genes encoding proteins involved in centrosomes and DNA repair pathways. However, it can also be induced by exposure to ionizing radiation and intrauterine infections such as the Zika virus. This review explains mammalian cortical development and the major DNA repair pathways that may lead to microcephaly when impaired. Next, we discuss the mechanisms and possible exposures leading to DNA damage and p53 hyperactivation culminating in microcephaly.
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Affiliation(s)
- Jessica Honorato Ribeiro
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
- Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Nazlican Altinisik
- Laboratory for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, University Hospital, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Nicholas Rajan
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Mieke Verslegers
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
- Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jay Gopalakrishnan
- Laboratory for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, University Hospital, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Roel Quintens
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
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