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Torrecilla I, Ruggiano A, Kiianitsa K, Aljarbou F, Lascaux P, Hoslett G, Song W, Maizels N, Ramadan K. Isolation and detection of DNA-protein crosslinks in mammalian cells. Nucleic Acids Res 2024; 52:525-547. [PMID: 38084926 PMCID: PMC10810220 DOI: 10.1093/nar/gkad1178] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 01/26/2024] Open
Abstract
DNA-protein crosslinks (DPCs) are toxic DNA lesions wherein a protein is covalently attached to DNA. If not rapidly repaired, DPCs create obstacles that disturb DNA replication, transcription and DNA damage repair, ultimately leading to genome instability. The persistence of DPCs is associated with premature ageing, cancer and neurodegeneration. In mammalian cells, the repair of DPCs mainly relies on the proteolytic activities of SPRTN and the 26S proteasome, complemented by other enzymes including TDP1/2 and the MRN complex, and many of the activities involved are essential, restricting genetic approaches. For many years, the study of DPC repair in mammalian cells was hindered by the lack of standardised assays, most notably assays that reliably quantified the proteins or proteolytic fragments covalently bound to DNA. Recent interest in the field has spurred the development of several biochemical methods for DPC analysis. Here, we critically analyse the latest techniques for DPC isolation and the benefits and drawbacks of each. We aim to assist researchers in selecting the most suitable isolation method for their experimental requirements and questions, and to facilitate the comparison of results across different laboratories using different approaches.
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Affiliation(s)
- Ignacio Torrecilla
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Annamaria Ruggiano
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, Seattle, WA 98195-7350, USA
| | - Ftoon Aljarbou
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Pauline Lascaux
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Gwendoline Hoslett
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Wei Song
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Nancy Maizels
- Department of Immunology, University of Washington, Seattle, WA 98195-7350, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7350, USA
| | - Kristijan Ramadan
- The MRC Weatherall Institute of Molecular Medicine, Department of Oncology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
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Kiianitsa K, Lukes ME, Hayes BJ, Brutman J, Valdmanis PN, Bird TD, Raskind WH, Korvatska O. TREM2 variants that cause early dementia and increase Alzheimer's disease risk affect gene splicing. Brain 2024:awae014. [PMID: 38226698 DOI: 10.1093/brain/awae014] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 01/02/2024] [Accepted: 01/09/2024] [Indexed: 01/17/2024] Open
Abstract
Loss-of-function variants in the triggering receptor expressed on myeloid cells 2 (TREM2) are responsible for a spectrum of neurodegenerative disorders. In the homozygous state, they cause severe pathologies with early onset dementia, such as Nasu-Hakola disease (NHD) and behavioral variants of frontotemporal dementia (FTD), whereas heterozygous variants increase the risk of late-onset Alzheimer's disease (AD) and FTD. For over half of TREM2 variants found in families with recessive early onset dementia, the defect occurs at the transcript level via premature termination codons or aberrant splicing. The remaining variants are missense alterations thought to affect the protein; however, the underlying pathogenic mechanism is less clear. In this work, we tested whether these disease-associated TREM2 variants contribute to the pathology via altered splicing. Variants scored by SpliceAI algorithm were tested by a full-size TREM2 splicing reporter assay in different cell lines. The effect of variants was quantified by qRT-/RT-PCR and western blots. Nanostring nCounter was used to measure TREM2 RNA in the brains of NHD patients who carried spliceogenic variants. Exon skipping events were analyzed from brain RNA-Seq datasets available through the Accelerating Medicines Partnership for Alzheimer's Disease Consortium (AMP-AD). We found that for some NHD and early onset FTD-causing variants, splicing defects were the primary cause (D134G) or likely contributor to pathogenicity (V126G and K186N). Similar but milder effects on splicing of exons 2 and 3 were demonstrated for A130V, L133L and R136W enriched in patients with dementia. Moreover, the two most frequent missense variants associated with AD/FTD risk in European and African ancestries (R62H, 1% in Caucasians, and T96K, 12% in Africans) had splicing defects via excessive skipping of exon 2 and overproduction of a potentially antagonistic TREM2 protein isoform. The effect of R62H on exon 2 skipping was confirmed in three independent brain RNA-seq datasets. Our findings revealed an unanticipated complexity of pathogenic variation in TREM2, in which effects on post-transcriptional gene regulation and protein function often coexist. This necessitates the inclusion of computational and experimental analyses of splicing and mRNA processing for a better understanding of genetic variation in disease.
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Affiliation(s)
- Kostantin Kiianitsa
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
| | - Maria E Lukes
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Brian J Hayes
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Julianna Brutman
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Paul N Valdmanis
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, WA 98195, USA
- Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Medical Center, Seattle, WA 98108, USA
| | - Wendy H Raskind
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
- Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Medical Center, Seattle, WA 98108, USA
| | - Olena Korvatska
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
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Edelman WC, Kiianitsa K, Virmani T, Martinez RA, Young JE, Keene CD, Bird TD, Raskind WH, Korvatska O. Reduced gene dosage is a common mechanism of neuropathologies caused by ATP6AP2 splicing mutations. Parkinsonism Relat Disord 2022; 101:31-38. [PMID: 35779466 PMCID: PMC10012809 DOI: 10.1016/j.parkreldis.2022.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/26/2022] [Accepted: 06/20/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Mutations that alter splicing of X-linked ATP6AP2 cause a spectrum of neurodevelopmental and neurodegenerative pathologies including parkinsonism in affected males. All previously reported splicing mutations increase the level of a minor isoform with skipped exon 4 (Δe4) that encodes a functionally deficient protein. OBJECTIVES We investigated the pathogenic mechanism of a novel c.168+6T>A variant reported in a family with X-linked intellectual disability, epilepsy, and parkinsonism. We also analyzed ATP6AP2 splicing defects in brains of carriers of a c.345C>T variant associated with X-linked spasticity and parkinsonism. METHODS We generated induced pluripotent stem cells from patients with c.168+6T>A, reprogrammed them to neural progenitor cells and analyzed them by RNA-Seq and qRT-PCR. We also quantified ATP6AP2 isoforms in the brains of c.345C>T carriers by Nanostring nCounter. RESULTS The c.168+6T>A increased skipping of ATP6AP2 exon 2 and usage of cryptic intronic donor splice sites. This results in out-of-frame splicing products and a reciprocal 50% reduction in functional full-length ATP6AP2 transcripts. Neural progenitors of patients with c.168+6T>A exhibited downregulated neural development gene networks. Analysis of blood transcriptomes of c.168+6T>A carriers identified potential biomarkers of ATP6AP2 deficiency in non-neural tissues. The c.345C>T variant increased exon 4 skipping with concomitant decrease of full length ATP6AP2 in brains of carriers. CONCLUSION A common pathogenic consequence of splicing mutations affecting inclusion of different ATP6AP2 exons is reduction of the functional full-length transcript. The exacerbated ATP6AP2 splicing defect in brains of c.345C>T carriers is consistent with their CNS-restricted clinical presentations.
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Affiliation(s)
- William C Edelman
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA
| | | | - Tuhin Virmani
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Refugio A Martinez
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Jessica E Young
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - C Dirk Keene
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, WA, USA; Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Medical Center, Seattle, WA, USA
| | - Wendy H Raskind
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA; Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, USA; Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Medical Center, Seattle, WA, USA
| | - Olena Korvatska
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, USA; Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Medical Center, Seattle, WA, USA.
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4
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Kiianitsa K, Kurtz I, Beeman N, Matsushita M, Chien WM, Raskind WH, Korvatska O. Novel TREM2 splicing isoform that lacks the V-set immunoglobulin domain is abundant in the human brain. J Leukoc Biol 2021; 110:829-837. [PMID: 34061398 PMCID: PMC10433532 DOI: 10.1002/jlb.2hi0720-463rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [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: 07/23/2020] [Revised: 05/03/2021] [Accepted: 05/17/2021] [Indexed: 12/20/2022] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is an immunoglobulin-like receptor expressed by certain myeloid cells, such as macrophages, dendritic cells, osteoclasts, and microglia. In the brain, TREM2 plays an important role in the immune function of microglia, and its dysfunction is linked to various neurodegenerative conditions in humans. Ablation of TREM2 or its adaptor protein TYROBP causes polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (also known as Nasu-Hakola disorder) with early onset of dementia, whereas some missense variants in TREM2 are associated with an increased risk of late-onset Alzheimer's disease. The human TREM2 gene is subject to alternative splicing, and its major, full-length canonic transcript encompasses 5 exons. Herein, we report a novel alternatively spliced TREM2 isoform without exon 2 (Δe2), which constitutes a sizable fraction of TREM2 transcripts and has highly variable inter-individual expression in the human brain (average frequency 10%; range 3.7-35%). The protein encoded by Δe2 lacks a V-set immunoglobulin domain from its extracellular part but retains its transmembrane and cytoplasmic domains. We demonstrated Δe2 protein expression in TREM2-positive THP-1 cells, in which the expression of full-length transcript was precluded by CRISPR/Cas9 disruption of the exon 2 coding frame. Similar to the full-length TREM2, Δe2 is sorted to the plasma membrane and is subject to receptor shedding. In "add-back" experiments, Δe2 TREM2 had diminished capacity to restore phagocytosis of amyloid beta peptide and promote IFN-I response as compared to full-length TREM2. Our findings suggest that changes in the balance of two mutually exclusive TREM2 isoforms may modify the dosage of full-length transcript potentially weakening some TREM2 receptor functions in the human brain.
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Affiliation(s)
| | - Irina Kurtz
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, USA
| | - Neal Beeman
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, USA
| | - Mark Matsushita
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, USA
| | - Wei-Ming Chien
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, USA
| | - Wendy H. Raskind
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, USA
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, USA
- Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Medical Center, Seattle, USA
- Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Medical Center, Seattle, USA
| | - Olena Korvatska
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, USA
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5
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Abstract
Topoisomerases are enzymes that play essential roles in DNA replication, transcription, chromosome segregation, and recombination. All cells have two major forms of DNA topoisomerases: type I enzymes, which make single-stranded cuts in DNA, and type II enzymes, which cut and decatenate double-stranded DNA. DNA topoisomerases are important targets of approved and experimental anti-cancer agents. Provided in this article are protocols to assess activities of topoisomerases and their inhibitors. Included are an assay for topoisomerase I activity based on relaxation of supercoiled DNA; an assay for topoisomerase II based on the decatenation of double-stranded DNA; and approaches for enriching and quantifying DNA-protein covalent complexes formed as obligatory intermediates in the reactions of type I and II topoisomerases with DNA; and assays for measuring DNA cleavage in vitro. Topoisomerases are not the only proteins that form covalent adducts with DNA in living cells, and the approaches described here are likely to find use in characterizing other protein-DNA adducts and exploring their utility as targets for therapy. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Assay of topoisomerase I activity Basic Protocol 2: Assay of topoisomerase II activity Basic Protocol 3: In vivo determination of topoisomerase covalent complexes using the in vivo complex of enzyme (ICE) assay Support Protocol 1: Preparation of mouse tissue for determination of topoisomerase covalent complexes using the ICE assay Support Protocol 2: Using recombinant topoisomerase standard for absolute quantification of cellular TOP2CC Basic Protocol 4: Quantification of topoisomerase-DNA covalent complexes by RADAR/ELISA: The rapid approach to DNA adduct recovery (RADAR) combined with the enzyme-linked immunosorbent assay (ELISA) Basic Protocol 5: Analysis of protein-DNA covalent complexes by RADAR/Western Support Protocol 3: Adduct-Seq to characterize adducted DNA Support Protocol 4: Nuclear fractionation and RNase treatment to reduce sample complexity Basic Protocol 6: Determination of DNA cleavage by purified topoisomerase I Basic Protocol 7: Determination of inhibitor effects on DNA cleavage by topoisomerase II using a plasmid linearization assay Alternate Protocol: Gel electrophoresis determination of topoisomerase II cleavage.
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Affiliation(s)
- John L Nitiss
- Pharmaceutical Sciences Department, University of Illinois College of Pharmacy, Rockford, Illinois
| | - Kostantin Kiianitsa
- Departments of Immunology and Biochemistry, University of Washington, Seattle, Washington
| | - Yilun Sun
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland
| | - Karin C Nitiss
- Pharmaceutical Sciences Department, University of Illinois College of Pharmacy, Rockford, Illinois.,Biomedical Sciences Department, University of Illinois College of Medicine, Rockford, Illinois
| | - Nancy Maizels
- Departments of Immunology and Biochemistry, University of Washington, Seattle, Washington
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6
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Kiianitsa K, Zhang Y, Maizels N. Treatment of human cells with 5-aza-dC induces formation of PARP1-DNA covalent adducts at genomic regions targeted by DNMT1. DNA Repair (Amst) 2020; 96:102977. [PMID: 33039802 DOI: 10.1016/j.dnarep.2020.102977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 12/13/2022]
Abstract
The nucleoside analog 5-aza-2'-deoxycytidine (5-aza-dC) is used to treat some hematopoietic malignancies. The mechanism of cell killing depends upon DNMT1, but is otherwise not clearly defined. Here we show that PARP1 forms covalent DNA adducts in human lymphoblast or fibroblasts treated with 5-aza-dC. Some adducts recovered from 5-aza-dC-treated cells have undergone cleavage by apoptotic caspases 3/7. Mapping of PARP1-DNA adducts, by a new method, "Adduct-Seq", demonstrates adduct enrichment at CpG-dense genomic locations that are targets of maintenance methylation by DNMT1. Covalent protein-DNA adducts can arrest replication and induce apoptosis, and these results raise the possibility that induction of PARP1-DNA adducts may contribute to cell killing in response to treatment with 5-aza-dC.
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Affiliation(s)
| | - Yinbo Zhang
- Department of Immunology, University of Washington, Seattle, WA, 98195, USA
| | - Nancy Maizels
- Department of Immunology, University of Washington, Seattle, WA, 98195, USA; Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA.
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7
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Korvatska O, Kiianitsa K, Ratushny A, Matsushita M, Beeman N, Chien WM, Satoh JI, Dorschner MO, Keene CD, Bammler TK, Bird TD, Raskind WH. Triggering Receptor Expressed on Myeloid Cell 2 R47H Exacerbates Immune Response in Alzheimer's Disease Brain. Front Immunol 2020; 11:559342. [PMID: 33101276 PMCID: PMC7546799 DOI: 10.3389/fimmu.2020.559342] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/25/2020] [Indexed: 01/11/2023] Open
Abstract
The R47H variant in the microglial triggering receptor expressed on myeloid cell 2 (TREM2) receptor is a strong risk factor for Alzheimer’s disease (AD). To characterize processes affected by R47H, we performed an integrative network analysis of genes expressed in brains of AD patients with R47H, sporadic AD without the variant, and patients with polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), systemic disease with early-onset dementia caused by loss-of-function mutations in TREM2 or its adaptor TYRO protein tyrosine kinase-binding protein (TYROBP). Although sporadic AD had few perturbed microglial and immune genes, TREM2 R47H AD demonstrated upregulation of interferon type I response and pro-inflammatory cytokines accompanied by induction of NKG2D stress ligands. In contrast, PLOSL had distinct sets of highly perturbed immune and microglial genes that included inflammatory mediators, immune signaling, cell adhesion, and phagocytosis. TREM2 knockout (KO) in THP1, a human myeloid cell line that constitutively expresses the TREM2- TYROBP receptor, inhibited response to the viral RNA mimetic poly(I:C) and phagocytosis of amyloid-beta oligomers; overexpression of ectopic TREM2 restored these functions. Compared with wild-type protein, R47H TREM2 had a higher stimulatory effect on the interferon type I response signature. Our findings point to a role of the TREM2 receptor in the control of the interferon type I response in myeloid cells and provide insight regarding the contribution of R47H TREM2 to AD pathology.
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Affiliation(s)
- Olena Korvatska
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, Seattle, WA, United States
| | - Alexander Ratushny
- Seattle Biomedical Research Institute and Institute for Systems Biology, Seattle, WA, United States
| | - Mark Matsushita
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
| | - Neal Beeman
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
| | - Wei-Ming Chien
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States
| | - Jun-Ichi Satoh
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Tokyo, Japan
| | - Michael O Dorschner
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - Theo K Bammler
- Department of Environmental and Occupational Health Sciences, Seattle, WA, United States
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, WA, United States.,Geriatric Research, Education and Clinical Center, Veteran Affairs Puget Sound Health Care System, Seattle, WA, United States
| | - Wendy H Raskind
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States.,Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA, United States.,Geriatric Research, Education and Clinical Center, Veteran Affairs Puget Sound Health Care System, Seattle, WA, United States.,Mental Illness Research, Education and Clinical Center, Department of Veteran Affairs, Seattle, WA, United States
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8
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Sinha D, Kiianitsa K, Sherman DR, Maizels N. Rapid, direct detection of bacterial topoisomerase 1-DNA adducts by RADAR/ELISA. Anal Biochem 2020; 608:113827. [PMID: 32738213 DOI: 10.1016/j.ab.2020.113827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 10/23/2022]
Abstract
Topoisomerases are proven drug targets, but antibiotics that poison bacterial Topoisomerase 1 (Top1) have yet to be discovered. We have developed a rapid and direct assay for quantification of Top1-DNA adducts that is suitable for high throughput assays. Adducts are recovered by "RADAR fractionation", a quick, convenient approach in which cells are lysed in chaotropic salts and detergent and nucleic acids and covalently bound adducts then precipitated with alcohol. Here we show that RADAR fractionation followed by ELISA immunodetection can quantify adducts formed by wild-type and mutant Top1 derivatives encoded by two different bacterial pathogens, Y. pestis and M. tuberculosis, expressed in E. coli or M. smegmatis, respectively. For both enzymes, quantification of adducts by RADAR/ELISA produces results comparable to the more cumbersome classical approach of CsCl density gradient fractionation. The experiments reported here establish that RADAR/ELISA assay offers a simple way to characterize Top1 mutants and analyze kinetics of adduct formation and repair. They also provide a foundation for discovery and optimization of drugs that poison bacterial Top1 using standard high-throughput approaches.
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Affiliation(s)
- Devapriya Sinha
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA.
| | - David R Sherman
- Department of Microbiology, University of Washington, 815 Republican St., Seattle, WA, 98102, USA
| | - Nancy Maizels
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA; Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA
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9
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Kiianitsa K, Maizels N. The "adductome": A limited repertoire of adducted proteins in human cells. DNA Repair (Amst) 2020; 89:102825. [PMID: 32109764 DOI: 10.1016/j.dnarep.2020.102825] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/10/2020] [Accepted: 02/18/2020] [Indexed: 01/20/2023]
Abstract
Proteins form adducts with nucleic acids in a variety of contexts, and these adducts may be cytotoxic if not repaired. Here we apply a proteomic approach to identification of proteins adducted to DNA or RNA in normally proliferating cells. This approach combines RADAR fractionation of proteins covalently bound to nucleic acids with quantitative mass spectrometry (MS). We demonstrate that "RADAR-MS" can quantify induction of TOP1- or TOP2-DNA adducts in cells treated with topotecan or etoposide, respectively, and also identify intermediates in physiological adduct repair. We validate RADAR-MS for discovery of previously unknown adducts by determining the repertoires of adducted proteins in two different normally proliferating human cell lines, CCRF-CEM T cells and GM639 fibroblasts. These repertoires are significantly similar with one another and exhibit robust correlations in their quantitative profiles (Spearman r = 0.52). A very similar repertoire is identified by the classical approach of CsCl buoyant density gradient centrifugation. We find that in normally proliferating human cells, the repertoire of adducted proteins - the "adductome" - is comprised of a limited number of proteins belonging to specific functional groups, and that it is greatly enriched for histones, HMG proteins and proteins involved in RNA splicing. Treatment with low concentrations of formaldehyde caused little change in the composition of the repertoire of adducted proteins, suggesting that reactive aldehydes generated by ongoing metabolic processes may contribute to protein adduction in normally proliferating cells. The identification of an endogenous adductome highlights the importance of adduct repair in maintaining genomic structure and the potential for deficiencies in adduct repair to contribute to cancer.
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Affiliation(s)
- Kostantin Kiianitsa
- Department of Immunology, 1959 NE Pacific St. Seattle, 98195 WA, United States
| | - Nancy Maizels
- Department of Immunology, 1959 NE Pacific St. Seattle, 98195 WA, United States; Department of Biochemistry, University of Washington Medical School, 1959 NE Pacific St. Seattle, 98195 WA, United States of America.
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10
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Olson HC, Davis L, Kiianitsa K, Khoo KJ, Liu Y, Knijnenburg TA, Maizels N. Increased levels of RECQ5 shift DNA repair from canonical to alternative pathways. Nucleic Acids Res 2019; 46:9496-9509. [PMID: 30107528 PMCID: PMC6182128 DOI: 10.1093/nar/gky727] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [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: 01/02/2018] [Accepted: 08/02/2018] [Indexed: 12/11/2022] Open
Abstract
RECQ5 (RECQL5) is one of several human helicases that dissociates RAD51-DNA filaments. The gene that encodes RECQ5 is frequently amplified in human tumors, but it is not known whether amplification correlates with increased gene expression, or how increased RECQ5 levels affect DNA repair at nicks and double-strand breaks. Here, we address these questions. We show that RECQ5 gene amplification correlates with increased gene expression in human tumors, by in silico analysis of over 9000 individual tumors representing 32 tumor types in the TCGA dataset. We demonstrate that, at double-strand breaks, increased RECQ5 levels inhibited canonical homology-directed repair (HDR) by double-stranded DNA donors, phenocopying the effect of BRCA deficiency. Conversely, at nicks, increased RECQ5 levels stimulated 'alternative' HDR by single-stranded DNA donors, which is normally suppressed by RAD51; this was accompanied by stimulation of mutagenic end-joining. Even modest changes (2-fold) in RECQ5 levels caused significant dysregulation of repair, especially HDR. These results suggest that in some tumors, RECQ5 gene amplification may have profound consequences for genomic instability.
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Affiliation(s)
- Henry C Olson
- Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Luther Davis
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Kevin J Khoo
- Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA.,Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 E. Duarte Road, Duarte, CA 91010, USA
| | - Theo A Knijnenburg
- Institute for Systems Biology, 401 Terry Ave. N., Seattle, WA 98109, USA
| | - Nancy Maizels
- Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA.,Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
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Korvatska O, Leverenz JB, Jayadev S, McMillan P, Kurtz I, Guo X, Rumbaugh M, Matsushita M, Girirajan S, Dorschner MO, Kiianitsa K, Yu CE, Brkanac Z, Garden GA, Raskind WH, Bird TD. R47H Variant of TREM2 Associated With Alzheimer Disease in a Large Late-Onset Family: Clinical, Genetic, and Neuropathological Study. JAMA Neurol 2015; 72:920-7. [PMID: 26076170 DOI: 10.1001/jamaneurol.2015.0979] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IMPORTANCE The R47H variant in the triggering receptor expressed on myeloid cells 2 gene (TREM2), a modulator of the immune response of microglia, is a strong genetic risk factor for Alzheimer disease (AD) and possibly other neurodegenerative disorders. OBJECTIVE To investigate a large family with late-onset AD (LOAD), in which R47H cosegregated with 75% of cases. DESIGN, SETTING, AND PARTICIPANTS This study includes genetic and pathologic studies of families with LOAD from 1985 to 2014. A total of 131 families with LOAD (751 individuals) were included from the University of Washington Alzheimer Disease Research Center. To identify LOAD genes/risk factors in the LOAD123 family with 21 affected members and 12 autopsies, we sequenced 4 exomes. Candidate variants were tested for cosegregation with the disease. TREM2 R47H was genotyped in an additional 130 families with LOAD. We performed clinical and neuropathological assessments of patients with and without R47H and evaluated the variant's effect on brain pathology, cellular morphology, and expression of microglial markers. MAIN OUTCOMES AND MEASURES We assessed the effect of TREM2 genotype on age at onset and disease duration. We compared Braak and Consortium to Establish a Registry for Alzheimer's Disease scores, presence of α-synuclein and TAR DNA-binding protein 43 aggregates, and additional vascular or Parkinson pathology in TREM2 R47H carriers vs noncarriers. Microglial activation was assessed by quantitative immunohistochemistry and morphometry. RESULTS Twelve of 16 patients with AD in the LOAD123 family carried R47H. Eleven patients with dementia had apolipoprotein E 4 (ApoE4) and R47H genotypes. We also found a rare missense variant, D353N, in a nominated AD risk gene, unc-5 homolog C (UNC5C), in 5 affected individuals in the LOAD123 family. R47H carriers demonstrated a shortened disease duration (mean [SD], 6.7 [2.8] vs 11.1 [6.6] years; 2-tailed t test; P = .04) and more frequent α-synucleinopathy. The panmicroglial marker ionized calcium-binding adapter molecule 1 was decreased in all AD cases and the decrease was most pronounced in R47H carriers (mean [SD], in the hilus: 0.114 [0.13] for R47H_AD vs 0.574 [0.26] for control individuals; 2-tailed t test; P = .005 and vs 0.465 [0.32] for AD; P = .02; in frontal cortex gray matter: 0.006 [0.004] for R47H_AD vs 0.016 [0.01] for AD; P = .04 and vs 0.033 [0.013] for control individuals; P < .001). Major histocompatibility complex class II, a marker of microglial activation, was increased in all patients with AD (AD: 2.5, R47H_AD: 2.7, and control: 1.0; P < .01). CONCLUSIONS AND RELEVANCE Our results demonstrate a complex genetic landscape of LOAD, even in a single pedigree with an apparent autosomal dominant pattern of inheritance. ApoE4, TREM2 R47H, and rare variants in other genes, such as UNC5C D353N, are likely responsible for the notable occurrence of AD in this family. Our findings support the role of the TREM2 receptor in microglial clearance of aggregation-prone proteins that is compromised in R47H carriers and may accelerate the course of disease.
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Affiliation(s)
- Olena Korvatska
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle
| | - James B Leverenz
- Lou Ruvo Center for Brain Health, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Suman Jayadev
- Department of Neurology, University of Washington, Seattle
| | - Pamela McMillan
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle4Mental Illness Research, Education, and Clinical Center, Department of Veteran Affairs, Seattle, Washington
| | - Irina Kurtz
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle
| | - Xindi Guo
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle
| | - Malia Rumbaugh
- Department of Neurology, University of Washington, Seattle
| | - Mark Matsushita
- Department of Medicine (Medical Genetics), University of Washington, Seattle
| | - Santhosh Girirajan
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College7Department of Anthropology, Pennsylvania State University, State College
| | - Michael O Dorschner
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle8Department of Pathology, University of Washington, Seattle
| | - Kostantin Kiianitsa
- Department of Medicine (Medical Genetics), University of Washington, Seattle
| | - Chang-En Yu
- Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System, Seattle, Washington10Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle
| | - Zoran Brkanac
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle
| | - Gwenn A Garden
- Department of Neurology, University of Washington, Seattle8Department of Pathology, University of Washington, Seattle
| | - Wendy H Raskind
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle4Mental Illness Research, Education, and Clinical Center, Department of Veteran Affairs, Seattle, Washington5Department of Medicine (Medical Genetics), University of Washin
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle5Department of Medicine (Medical Genetics), University of Washington, Seattle9Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System, Seattle, Washington
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Abstract
Enzymes that form transient DNA-protein covalent complexes are targets for several potent classes of drugs used to treat infectious disease and cancer, making it important to establish robust and rapid procedures for analysis of these complexes. We report a method for isolation of DNA-protein adducts and their identification and quantification, using techniques compatible with high-throughput screening. This method is based on the RADAR assay for DNA adducts that we previously developed (Kiianitsa and Maizels (2013) A rapid and sensitive assay for DNA-protein covalent complexes in living cells. Nucleic Acids Res., 41:e104), but incorporates three key new steps of broad applicability. (i) Silica-assisted ethanol/isopropanol precipitation ensures reproducible and efficient recovery of DNA and DNA-protein adducts at low centrifugal forces, enabling cell culture and DNA precipitation to be carried out in a single microtiter plate. (ii) Rigorous purification of DNA-protein adducts by a procedure that eliminates free proteins and free nucleic acids, generating samples suitable for detection of novel protein adducts (e.g. by mass spectroscopy). (iii) Identification and quantification of DNA-protein adducts by direct ELISA assay. The ELISA-based RADAR assay can detect Top1-DNA and Top2a-DNA adducts in human cells, and gyrase-DNA adducts in Escherichia coli. This approach will be useful for discovery and characterization of new drugs to treat infectious disease and cancer, and for development of companion diagnostics assays for individualized medicine.
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Affiliation(s)
| | - Nancy Maizels
- Department of Immunology, University of Washington, Seattle, WA 98195, USA Department of Biochemistry, University of Washington, Seattle, WA 98195, USA Department of Pathology, University of Washington, Seattle, WA 98195, USA
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Abstract
A number of proteins form covalent bonds with DNA as obligatory transient intermediates in normal nuclear transactions. Drugs that trap these complexes have proven to be potent therapeutics in both cancer and infectious disease. Nonetheless, current assays for DNA–protein adducts are cumbersome, limiting both mechanistic studies and translational applications. We have developed a rapid and sensitive assay that enables quantitative immunodetection of protein–DNA adducts. This new ‘RADAR’ (rapid approach to DNA adduct recovery) assay accelerates processing time 4-fold, increases sample throughput 20-fold and requires 50-fold less starting material than the current standard. It can be used to detect topoisomerase 1-DNA adducts in as little as 60 ng of DNA, corresponding to 10 000 human cells. We apply the RADAR assay to demonstrate that expression of SLFN11 does not increase camptothecin sensitivity by promoting accumulation of topoisomerase 1-DNA adducts. The RADAR assay will be useful for analysis of the mechanisms of formation and resolution of DNA–protein adducts in living cells, and identification and characterization of reactions in which covalent DNA adducts are transient intermediates. The assay also has potential application to drug discovery and individualized medicine.
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Li X, Solinger JA, Kiianitsa K, Zhang XP, Heyer W. The role of the ATPase activities of the Rad51 and Rad54 proteins in the postsynaptic stage of homologous recombination. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.a942-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xuan Li
- MicrobiologyUniversity of CaliforniaOne Shields AveDavisCA95616
| | - J. A. Solinger
- MicrobiologyUniversity of CaliforniaOne Shields AveDavisCA95616
| | - K. Kiianitsa
- MicrobiologyUniversity of CaliforniaOne Shields AveDavisCA95616
| | - X. P. Zhang
- MicrobiologyUniversity of CaliforniaOne Shields AveDavisCA95616
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Abstract
The process of DNA strand exchange during general genetic recombination is initiated within protein-stabilized synaptic filaments containing homologous regions of interacting DNA molecules. The RecA protein in bacteria and its analogs in eukaryotic organisms start this process by forming helical filamentous complexes on single-stranded or partially single-stranded DNA molecules. These complexes then progressively bind homologous double-stranded DNA molecules so that homologous regions of single- and double-stranded DNA molecules become aligned in register while presumably winding around common axis. The topological assay presented herein allows us to conclude that in synaptic complexes containing homologous single- and double-stranded DNA molecules, all three DNA strands have a helicity of approximately 19 nt per turn.
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Affiliation(s)
- K Kiianitsa
- Laboratoire d'Analyse Ultrastructurale, Université de Lausanne, CH-1015 Lausanne-Dorigny, Switzerland
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