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Zhu Y, Han XQ, Sun XJ, Yang R, Ma WQ, Liu NF. Lactate accelerates vascular calcification through NR4A1-regulated mitochondrial fission and BNIP3-related mitophagy. Apoptosis 2021; 25:321-340. [PMID: 31993850 DOI: 10.1007/s10495-020-01592-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Arterial media calcification is related to mitochondrial dysfunction. Protective mitophagy delays the progression of vascular calcification. We previously reported that lactate accelerates osteoblastic phenotype transition of VSMC through BNIP3-mediated mitophagy suppression. In this study, we investigated the specific links between lactate, mitochondrial homeostasis, and vascular calcification. Ex vivo, alizarin S red and von Kossa staining in addition to measurement of calcium content, RUNX2, and BMP-2 protein levels revealed that lactate accelerated arterial media calcification. We demonstrated that lactate induced mitochondrial fission and apoptosis in aortas, whereas mitophagy was suppressed. In VSMCs, lactate increased NR4A1 expression, leading to activation of DNA-PKcs and p53. Lactate induced Drp1 migration to the mitochondria and enhanced mitochondrial fission through NR4A1. Western blot analysis of LC3-II and p62 and mRFP-GFP-LC3 adenovirus detection showed that NR4A1 knockdown was involved in enhanced autophagy flux. Furthermore, NR4A1 inhibited BNIP3-related mitophagy, which was confirmed by TOMM20 and BNIP3 protein levels, and LC3-II co-localization with TOMM20. The excessive fission and deficient mitophagy damaged mitochondrial structure and impaired respiratory function, determined by mPTP opening rate, mitochondrial membrane potential, mitochondrial morphology under TEM, ATP production, and OCR, which was reversed by NR4A1 silencing. Mechanistically, lactate enhanced fission but halted mitophagy via activation of the NR4A1/DNA-PKcs/p53 pathway, evoking apoptosis, finally accelerating osteoblastic phenotype transition of VSMC and calcium deposition. This study suggests that the NR4A1/DNA-PKcs/p53 pathway is involved in the mechanism by which lactate accelerates vascular calcification, partly through excessive Drp-mediated mitochondrial fission and BNIP3-related mitophagy deficiency.
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Affiliation(s)
- Yi Zhu
- Department of Cardiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, People's Republic of China
| | - Xi-Qiong Han
- Department of Cardiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, People's Republic of China
| | - Xue-Jiao Sun
- Department of Cardiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, People's Republic of China
| | - Rui Yang
- Pharmaceutical Department, Shandong Provincial Qianfoshan Hospital, Jinan, 250014, People's Republic of China
| | - Wen-Qi Ma
- Department of Cardiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, People's Republic of China
| | - Nai-Feng Liu
- Department of Cardiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, People's Republic of China.
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2
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Zahid S, Seif El Dahan M, Iehl F, Fernandez-Varela P, Le Du MH, Ropars V, Charbonnier JB. The Multifaceted Roles of Ku70/80. Int J Mol Sci 2021; 22:ijms22084134. [PMID: 33923616 PMCID: PMC8073936 DOI: 10.3390/ijms22084134] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 12/11/2022] Open
Abstract
DNA double-strand breaks (DSBs) are accidental lesions generated by various endogenous or exogenous stresses. DSBs are also genetically programmed events during the V(D)J recombination process, meiosis, or other genome rearrangements, and they are intentionally generated to kill cancer during chemo- and radiotherapy. Most DSBs are processed in mammalian cells by the classical nonhomologous end-joining (c-NHEJ) pathway. Understanding the molecular basis of c-NHEJ has major outcomes in several fields, including radiobiology, cancer therapy, immune disease, and genome editing. The heterodimer Ku70/80 (Ku) is a central actor of the c-NHEJ as it rapidly recognizes broken DNA ends in the cell and protects them from nuclease activity. It subsequently recruits many c-NHEJ effectors, including nucleases, polymerases, and the DNA ligase 4 complex. Beyond its DNA repair function, Ku is also involved in several other DNA metabolism processes. Here, we review the structural and functional data on the DNA and RNA recognition properties of Ku implicated in DNA repair and in telomeres maintenance.
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3
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Gavande NS, VanderVere-Carozza PS, Pawelczak KS, Mendoza-Munoz P, Vernon TL, Hanakahi LA, Summerlin M, Dynlacht JR, Farmer AH, Sears CR, Nasrallah NA, Garrett J, Turchi JJ. Discovery and development of novel DNA-PK inhibitors by targeting the unique Ku-DNA interaction. Nucleic Acids Res 2020; 48:11536-11550. [PMID: 33119767 PMCID: PMC7672428 DOI: 10.1093/nar/gkaa934] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/02/2020] [Accepted: 10/09/2020] [Indexed: 01/05/2023] Open
Abstract
DNA-dependent protein kinase (DNA-PK) plays a critical role in the non-homologous end joining (NHEJ) repair pathway and the DNA damage response (DDR). DNA-PK has therefore been pursued for the development of anti-cancer therapeutics in combination with ionizing radiation (IR). We report the discovery of a new class of DNA-PK inhibitors that act via a novel mechanism of action, inhibition of the Ku-DNA interaction. We have developed a series of highly potent and specific Ku-DNA binding inhibitors (Ku-DBi's) that block the Ku-DNA interaction and inhibit DNA-PK kinase activity. Ku-DBi's directly interact with the Ku and inhibit in vitro NHEJ, cellular NHEJ, and potentiate the cellular activity of radiomimetic agents and IR. Analysis of Ku-null cells demonstrates that Ku-DBi's cellular activity is a direct result of Ku inhibition, as Ku-null cells are insensitive to Ku-DBi's. The utility of Ku-DBi's was also revealed in a CRISPR gene-editing model where we demonstrate that the efficiency of gene insertion events was increased in cells pre-treated with Ku-DBi's, consistent with inhibition of NHEJ and activation of homologous recombination to facilitate gene insertion. These data demonstrate the discovery and application of new series of compounds that modulate DNA repair pathways via a unique mechanism of action.
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Affiliation(s)
- Navnath S Gavande
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
- Department of Pharmaceutical Sciences, Wayne State University College of Pharmacy and Health Sciences, Detroit, MI 48201, USA
| | | | | | - Pamela Mendoza-Munoz
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
| | - Tyler L Vernon
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
| | - Leslyn A Hanakahi
- Department of Biopharmaceutical Sciences, University of Illinois College of Pharmacy, Rockford, IL 61107, USA
| | - Matthew Summerlin
- Department of Biopharmaceutical Sciences, University of Illinois College of Pharmacy, Rockford, IL 61107, USA
| | - Joseph R Dynlacht
- Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Annabelle H Farmer
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
| | - Catherine R Sears
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
| | - Nawar Al Nasrallah
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
| | - Joy Garrett
- Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - John J Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis IN 46202, USA
- NERx Biosciences, 212 W 10th St. Suite A480, Indianapolis, IN 46202, USA
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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4
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Ruff SE, Logan SK, Garabedian MJ, Huang TT. Roles for MDC1 in cancer development and treatment. DNA Repair (Amst) 2020; 95:102948. [PMID: 32866776 DOI: 10.1016/j.dnarep.2020.102948] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 12/28/2022]
Abstract
The DNA damage response (DDR) is necessary to maintain genome integrity and prevent the accumulation of oncogenic mutations. Consequently, proteins involved in the DDR often serve as tumor suppressors, carrying out the crucial task of keeping DNA fidelity intact. Mediator of DNA damage checkpoint 1 (MDC1) is a scaffold protein involved in the early steps of the DDR. MDC1 interacts directly with γ-H2AX, the phosphorylated form of H2AX, a commonly used marker for DNA damage. It then propagates the phosphorylation of H2AX by recruiting ATM kinase. While the function of MDC1 in the DDR has been reviewed previously, its role in cancer has not been reviewed, and numerous studies have recently identified a link between MDC1 and carcinogenesis. This includes MDC1 functioning as a tumor suppressor, with its loss serving as a biomarker for cancer and contributor to drug sensitivity. Studies also indicate that MDC1 operates outside of its traditional role in DDR, and functions as a co-regulator of nuclear receptor transcriptional activity, and that mutations in MDC1 are present in tumors and can also cause germline predisposition to cancer. This review will discuss reports that link MDC1 to cancer and identify MDC1 as an important player in tumor formation, progression, and treatment. We also discuss mechanisms by which MDC1 levels are regulated and how this contributes to tumor formation.
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Affiliation(s)
- Sophie E Ruff
- Department of Microbiology, New York University School of Medicine, New York, NY, 10016, USA; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA
| | - Susan K Logan
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA; Department of Urology, New York University School of Medicine, New York, NY, 10016, USA
| | - Michael J Garabedian
- Department of Microbiology, New York University School of Medicine, New York, NY, 10016, USA; Department of Urology, New York University School of Medicine, New York, NY, 10016, USA.
| | - Tony T Huang
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, 10016, USA.
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Onn L, Portillo M, Ilic S, Cleitman G, Stein D, Kaluski S, Shirat I, Slobodnik Z, Einav M, Erdel F, Akabayov B, Toiber D. SIRT6 is a DNA double-strand break sensor. eLife 2020; 9:51636. [PMID: 31995034 PMCID: PMC7051178 DOI: 10.7554/elife.51636] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/23/2020] [Indexed: 12/18/2022] Open
Abstract
DNA double-strand breaks (DSB) are the most deleterious type of DNA damage. In this work, we show that SIRT6 directly recognizes DNA damage through a tunnel-like structure that has high affinity for DSB. SIRT6 relocates to sites of damage independently of signaling and known sensors. It activates downstream signaling for DSB repair by triggering ATM recruitment, H2AX phosphorylation and the recruitment of proteins of the homologous recombination and non-homologous end joining pathways. Our findings indicate that SIRT6 plays a previously uncharacterized role as a DNA damage sensor, a critical factor in initiating the DNA damage response (DDR). Moreover, other Sirtuins share some DSB-binding capacity and DDR activation. SIRT6 activates the DDR before the repair pathway is chosen, and prevents genomic instability. Our findings place SIRT6 as a sensor of DSB, and pave the road to dissecting the contributions of distinct DSB sensors in downstream signaling. DNA is a double-stranded molecule in which the two strands run in opposite directions, like the lanes on a two-lane road. Also like a road, DNA can be damaged by use and adverse conditions. Double-strand breaks – where both strands of DNA snap at once – are the most dangerous type of DNA damage, so cells have systems in place to rapidly detect and repair this kind of damage. There are three confirmed sensors for double-strand break in human cells. A fourth protein, known as SIRT6, arrives within five seconds of DNA damage, and was known to make the DNA more accessible so that it can be repaired. However, it was unclear whether SIRT6 could detect the double-strand break itself, or whether it was recruited to the damage by another double-strand break sensor. To address this issue, Onn et al. blocked the three other sensors in human cells and watched the response to DNA damage. Even when all the other sensors were inactive, SIRT6 still arrived at damaged DNA and activated the DNA damage response. To find out how SIRT6 sensed DNA damage, Onn et al. examined how purified SIRT6 interacts with different kinds of DNA. This revealed that SIRT6 sticks to broken DNA ends, especially if the end of one strand slightly overhangs the other – a common feature of double-strand breaks. A closer look at the structure of the SIRT6 protein revealed that it contains a narrow tube, which fits over the end of one broken DNA strand. When both strands break at once, two SIRT6 molecules cap the broken ends, joining together to form a pair. This pair not only protects the open ends of the DNA from further damage, it also sends signals to initiating repairs. In this way, SIRT6 could be thought of acting like a paramedic who arrives first on the scene of an accident and works to treat the injured while waiting for more specialized help to arrive. Understanding the SIRT6 sensor could improve knowledge about how cells repair their DNA. SIRT6 arrives before the cell chooses how to fix its broken DNA, so studying it further could reveal how that critical decision happens. This is important for medical research because DNA damage builds up in age-related diseases like cancer and neurodegeneration. In the long term, these findings can help us develop new treatments that target different types of DNA damage sensors.
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Affiliation(s)
- Lior Onn
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Miguel Portillo
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Stefan Ilic
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Gal Cleitman
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Daniel Stein
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shai Kaluski
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ido Shirat
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Zeev Slobodnik
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Monica Einav
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Fabian Erdel
- Division of Chromatin Networks, German Cancer Research Center (DKFZ), BioQuant, Heidelberg, Germany.,Centre de Biologie Intégrative, CNRS UPS, Toulouse, France
| | - Barak Akabayov
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Debra Toiber
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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6
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Plugged into the Ku-DNA hub: The NHEJ network. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 147:62-76. [PMID: 30851288 DOI: 10.1016/j.pbiomolbio.2019.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/26/2019] [Accepted: 03/01/2019] [Indexed: 12/16/2022]
Abstract
In vertebrates, double-strand breaks in DNA are primarily repaired by Non-Homologous End-Joining (NHEJ). The ring-shaped Ku heterodimer rapidly senses and threads onto broken DNA ends forming a recruiting hub. Through protein-protein contacts eventually reinforced by protein-DNA interactions, the Ku-DNA hub attracts a series of specialized proteins with scaffolding and/or enzymatic properties. To shed light on these dynamic interplays, we review here current knowledge on proteins directly interacting with Ku and on the contact points involved, with a particular accent on the different classes of Ku-binding motifs identified in several Ku partners. An integrated structural model of the core NHEJ network at the synapsis step is proposed.
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7
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Hecox-Lea BJ, Mark Welch DB. Evolutionary diversity and novelty of DNA repair genes in asexual Bdelloid rotifers. BMC Evol Biol 2018; 18:177. [PMID: 30486781 PMCID: PMC6264785 DOI: 10.1186/s12862-018-1288-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 11/02/2018] [Indexed: 11/26/2022] Open
Abstract
Background Bdelloid rotifers are the oldest, most diverse and successful animal taxon for which males, hermaphrodites, and traditional meiosis are unknown. Their degenerate tetraploid genome, with 2–4 copies of most loci, includes thousands of genes acquired from all domains of life by horizontal transfer. Many bdelloid species thrive in ephemerally aquatic habitats by surviving desiccation at any life stage with no loss of fecundity or lifespan. Their unique genomic diversity and the intense selective pressure of desiccation provide an exceptional opportunity to study the evolution of diversity and novelty in genes involved in DNA repair. Results We used genomic data and RNA-Seq of the desiccation process in the bdelloid Adineta vaga to characterize DNA damage reversal, translesion synthesis, and the major DNA repair pathways: base, nucleotide, and alternate excision repair, mismatch repair (MMR), and double strand break repair by homologous recombination (HR) and classical non-homologous end joining (NHEJ). We identify multiple horizontally transferred DNA damage response genes otherwise unknown in animals (AlkD, Fpg, LigK UVDE), and the presence of genes often considered vertebrate specific, particularly in the NHEJ complex and X family polymerases. While 75–100% of genes involved in MMR and HR are present in 0–2 copies, genes involved in NHEJ, which are present in only a single copy in nearly all other animals, are retained in 3–8 copies. We present structural predictions and expression evidence of neo- or sub-functionalization of multiple copy genes involved in NHEJ and other repair processes. Conclusion The horizontally-acquired genes and duplicated genes in BER and NHEJ suggest resilience to oxidative damage is conferred in part by increased DNA damage recognition and efficient end repair capabilities. The pattern of gene loss and retention in MMR and HR may facilitate recombination and gene conversion between divergent sequences, thus providing at least some of the benefits of sex. The unique retention and divergence of duplicates genes in NHEJ may be facilitated by the lack of efficient selection in the absence of meiotic recombination and independent assortment, and may contribute to the evolutionary success of bdelloids. Electronic supplementary material The online version of this article (10.1186/s12862-018-1288-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bette J Hecox-Lea
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA.,Department of Biology, Northeastern University, Boston, MA, USA
| | - David B Mark Welch
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, USA.
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8
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George VC, Ansari SA, Chelakkot VS, Chelakkot AL, Chelakkot C, Menon V, Ramadan W, Ethiraj KR, El-Awady R, Mantso T, Mitsiogianni M, Panagiotidis MI, Dellaire G, Vasantha Rupasinghe HP. DNA-dependent protein kinase: Epigenetic alterations and the role in genomic stability of cancer. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 780:92-105. [PMID: 31395353 DOI: 10.1016/j.mrrev.2018.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/13/2018] [Indexed: 12/28/2022]
Abstract
DNA-dependent protein kinase (DNA-PK), a member of phosphatidylinositol-kinase family, is a key protein in mammalian DNA double-strand break (DSB) repair that helps to maintain genomic integrity. DNA-PK also plays a central role in immune cell development and protects telomerase during cellular aging. Epigenetic deregulation due to endogenous and exogenous factors may affect the normal function of DNA-PK, which in turn could impair DNA repair and contribute to genomic instability. Recent studies implicate a role for epigenetics in the regulation of DNA-PK expression in normal and cancer cells, which may impact cancer progression and metastasis as well as provide opportunities for treatment and use of DNA-PK as a novel cancer biomarker. In addition, several small molecules and biological agents have been recently identified that can inhibit DNA-PK function or expression, and thus hold promise for cancer treatments. This review discusses the impact of epigenetic alterations and the expression of DNA-PK in relation to the DNA repair mechanisms with a focus on its differential levels in normal and cancer cells.
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Affiliation(s)
- Vazhappilly Cijo George
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Shabbir Ahmed Ansari
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Vipin Shankar Chelakkot
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | | | - Chaithanya Chelakkot
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Varsha Menon
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Wafaa Ramadan
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | | | - Raafat El-Awady
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates; Cancer Biology Department, National Cancer Institute and College of Medicine, Cairo University, Cairo, Egypt
| | - Theodora Mantso
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Melina Mitsiogianni
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Mihalis I Panagiotidis
- Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Graham Dellaire
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - H P Vasantha Rupasinghe
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada.
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9
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Pawelczak KS, Gavande NS, VanderVere-Carozza PS, Turchi JJ. Modulating DNA Repair Pathways to Improve Precision Genome Engineering. ACS Chem Biol 2018; 13:389-396. [PMID: 29210569 DOI: 10.1021/acschembio.7b00777] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Programmable nucleases like the popular CRISPR/Cas9 system allow for precision genome engineering by inducing a site-specific DNA double strand break (DSB) within a genome. The DSB is repaired by endogenous DNA repair pathways, either nonhomologous end joining (NHEJ) or homology directed repair (HDR). The predominant and error-prone NHEJ pathway often results in small nucleotide insertions or deletions that can be used to construct knockout alleles. Alternatively, HDR activity can result in precise modification incorporating exogenous DNA fragments into the cut site. However, genetic recombination in mammalian systems through the HDR pathway is an inefficient process and requires cumbersome laboratory methods to identify the desired accurate insertion events. This is further compromised by the activity of the competing DNA repair pathway, NHEJ, which repairs the majority of nuclease induced DNA DSBs and also is responsible for mutagenic insertion and deletion events at off-target locations throughout the genome. Various methodologies have been developed to increase the efficiency of designer nuclease-based HDR mediated gene editing. Here, we review these advances toward modulating the activities of the two critical DNA repair pathways, HDR and NHEJ, to enhance precision genome engineering.
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Affiliation(s)
- Katherine S. Pawelczak
- NERx Biosciences, 212 W 10th
Street, Suite A480, Indianapolis, Indiana 46202, United States
| | | | | | - John J. Turchi
- NERx Biosciences, 212 W 10th
Street, Suite A480, Indianapolis, Indiana 46202, United States
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10
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Zhou H, Du W, Li Y, Shi C, Hu N, Ma S, Wang W, Ren J. Effects of melatonin on fatty liver disease: The role of NR4A1/DNA-PKcs/p53 pathway, mitochondrial fission, and mitophagy. J Pineal Res 2018; 64. [PMID: 28981157 DOI: 10.1111/jpi.12450] [Citation(s) in RCA: 223] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 09/26/2017] [Indexed: 12/11/2022]
Abstract
Mitochondrial dysfunction has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) through poorly defined mechanisms. Melatonin supplementation has been found to protect liver function in diabetes and obesity. Here, we intensively explored the role and mechanism of melatonin in the development of NAFLD. We demonstrated that the onset of diet-induced NAFLD greatly caused NR4A1 upregulation in hepatocytes, leading to the activation of DNA-PKcs and p53. On the one hand, p53 aided Drp1 migration in the mitochondria and consequently drove mitochondrial fission. On the other hand, p53 repressed Bnip3 transcription and expression, resulting in mitophagy arrest. The excessive fission and deficient mitophagy dramatically mediated mitochondrial dysfunction, including extensive mPTP opening, reduction in mitochondrial potential, oxidative stress, calcium overload, mitochondrial respiratory collapse, and ATP shortage. However, genetic deletion of NR4A1 or DNA-PKcs could definitively reverse NAFLD progression and the mitochondrial dysfunction. Similarly, melatonin supplementation could robustly reduce the damage to liver and mitochondrial structure and function in NAFLD. Mechanistically, melatonin halted fission but recovered mitophagy via blockade of NR4A1/DNA-PKcs/p53 pathway, finally improving mitochondrial and liver function in the setting of NAFLD. Our results identify NR4A1/DNA-PKcs/p53 pathway as the novel molecular mechanism underlying the pathogenesis of NAFLD via regulation of Drp1-mediated mitochondrial fission and Bnip3-related mitophagy. Meanwhile, we also confirm that melatonin has the ability to cut off the NR4A1/DNA-PKcs/p53 pathway, which confers a protective advantage to hepatocytes and mitochondria. The manipulation of NR4A1/DNA-PKcs/p53 pathway by melatonin highlights a new entry point for treating NAFLD.
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Affiliation(s)
- Hao Zhou
- Department of Cardiology, Chinese PLA General Hospital, Medical School of Chinese PLA, Beijing, China
| | - Wenjuan Du
- Department of Cardiology, Chinese PLA General Hospital, Medical School of Chinese PLA, Beijing, China
| | - Ye Li
- Department of Cardiology, Chinese PLA General Hospital, Medical School of Chinese PLA, Beijing, China
| | - Chen Shi
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital and Institute, Beijing, China
| | - Nan Hu
- Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
| | - Sai Ma
- Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
| | - Weihu Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital and Institute, Beijing, China
| | - Jun Ren
- Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
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Yan Q, Zhu H, Lan L, Yi J, Yang J. Cleavage of Ku80 by caspase-2 promotes non-homologous end joining-mediated DNA repair. DNA Repair (Amst) 2017; 60:18-28. [DOI: 10.1016/j.dnarep.2017.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 10/06/2017] [Accepted: 10/08/2017] [Indexed: 12/12/2022]
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12
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Cryo-EM structure of human DNA-PK holoenzyme. Cell Res 2017; 27:1341-1350. [PMID: 28840859 DOI: 10.1038/cr.2017.110] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 07/22/2017] [Accepted: 07/27/2017] [Indexed: 02/07/2023] Open
Abstract
DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase complex composed of a catalytic subunit (DNA-PKcs) and KU70/80 heterodimer bound to DNA. DNA-PK holoenzyme plays a critical role in non-homologous end joining (NHEJ), the major DNA repair pathway. Here, we determined cryo-electron microscopy structure of human DNA-PK holoenzyme at 6.6 Å resolution. In the complex structure, DNA-PKcs, KU70, KU80 and DNA duplex form a 650-kDa heterotetramer with 1:1:1:1 stoichiometry. The N-terminal α-solenoid (∼2 800 residues) of DNA-PKcs adopts a double-ring fold and connects the catalytic core domain of DNA-PKcs and KU70/80-DNA. DNA-PKcs and KU70/80 together form a DNA-binding tunnel, which cradles ∼30-bp DNA and prevents sliding inward of DNA-PKcs along with DNA duplex, suggesting a mechanism by which the broken DNA end is protected from unnecessary processing. Structural and biochemical analyses indicate that KU70/80 and DNA coordinately induce conformational changes of DNA-PKcs and allosterically stimulate its kinase activity. We propose a model for activation of DNA-PKcs in which allosteric signals are generated upon DNA-PK holoenzyme formation and transmitted to the kinase domain through N-terminal HEAT repeats and FAT domain of DNA-PKcs. Our studies suggest a mechanism for recognition and protection of broken DNA ends and provide a structural basis for understanding the activation of DNA-PKcs and DNA-PK-mediated NHEJ pathway.
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13
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Radhakrishnan SK, Lees-Miller SP. DNA requirements for interaction of the C-terminal region of Ku80 with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). DNA Repair (Amst) 2017. [PMID: 28641126 DOI: 10.1016/j.dnarep.2017.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Non-homologous end joining (NHEJ) is the major pathway for the repair of ionizing radiation induced DNA double strand breaks (DSBs) in human cells. Critical to NHEJ is the DNA-dependent interaction of the Ku70/80 heterodimer with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to form the DNA-PK holoenzyme. However, precisely how Ku recruits DNA-PKcs to DSBs ends to enhance its kinase activity has remained enigmatic, with contradictory findings reported in the literature. Here we address the role of the Ku80 C-terminal region (CTR) in the DNA-dependent interaction of Ku70/80 with DNA-PKcs using purified components and defined DNA structures. Our results show that the Ku80 CTR is required for interaction with DNA-PKcs on short segments of blunt ended 25bp dsDNA or 25bp dsDNA with a 15-base poly dA single stranded (ss) DNA extension, but this requirement is less stringent on longer dsDNA molecules (35bp blunt ended dsDNA) or 25bp duplex DNA with either a 15-base poly dT or poly dC ssDNA extension. Moreover, the DNA-PKcs-Ku complex preferentially forms on 25 bp DNA with a poly-pyrimidine ssDNA extension.Our work clarifies the role of the Ku80 CTR and dsDNA ends on the interaction of DNA-PKcs with Ku and provides key information to guide assembly and biology of NHEJ complexes.
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Affiliation(s)
- Sarvan Kumar Radhakrishnan
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, University of Calgary, 3330 Hospital Drive NW, Alberta, T2N 1N4, Canada
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, University of Calgary, 3330 Hospital Drive NW, Alberta, T2N 1N4, Canada.
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14
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Sastre-Moreno G, Pryor JM, Moreno-Oñate M, Herrero-Ruiz AM, Cortés-Ledesma F, Blanco L, Ramsden DA, Ruiz JF. Regulation of human polλ by ATM-mediated phosphorylation during non-homologous end joining. DNA Repair (Amst) 2017; 51:31-45. [PMID: 28109743 DOI: 10.1016/j.dnarep.2017.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 11/26/2022]
Abstract
DNA double strand breaks (DSBs) trigger a variety of cellular signaling processes, collectively termed the DNA-damage response (DDR), that are primarily regulated by protein kinase ataxia-telangiectasia mutated (ATM). Among DDR activated processes, the repair of DSBs by non-homologous end joining (NHEJ) is essential. The proper coordination of NHEJ factors is mainly achieved through phosphorylation by an ATM-related kinase, the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), although the molecular basis for this regulation has yet to be fully elucidated. In this study we identify the major NHEJ DNA polymerase, DNA polymerase lambda (Polλ), as a target for both ATM and DNA-PKcs in human cells. We show that Polλ is efficiently phosphorylated by DNA-PKcs in vitro and predominantly by ATM after DSB induction with ionizing radiation (IR) in vivo. We identify threonine 204 (T204) as a main target for ATM/DNA-PKcs phosphorylation on human Polλ, and establish that its phosphorylation may facilitate the repair of a subset of IR-induced DSBs and the efficient Polλ-mediated gap-filling during NHEJ. Molecular evidence suggests that Polλ phosphorylation might favor Polλ interaction with the DNA-PK complex at DSBs. Altogether, our work provides the first demonstration of how Polλ is regulated by phosphorylation to connect with the NHEJ core machinery during DSB repair in human cells.
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Affiliation(s)
- Guillermo Sastre-Moreno
- Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid/CSIC, Madrid 28049, Spain
| | - John M Pryor
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Marta Moreno-Oñate
- Departamento Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, Sevilla 41092, Spain; Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain
| | - Andrés M Herrero-Ruiz
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain
| | - Felipe Cortés-Ledesma
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain
| | - Luis Blanco
- Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma de Madrid/CSIC, Madrid 28049, Spain
| | - Dale A Ramsden
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jose F Ruiz
- Departamento Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, Sevilla 41092, Spain; Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla 41092, Spain.
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15
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Liang Z, Sunder S, Nallasivam S, Wilson TE. Overhang polarity of chromosomal double-strand breaks impacts kinetics and fidelity of yeast non-homologous end joining. Nucleic Acids Res 2016; 44:2769-81. [PMID: 26773053 PMCID: PMC4824102 DOI: 10.1093/nar/gkw013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/05/2016] [Indexed: 12/21/2022] Open
Abstract
Non-homologous end joining (NHEJ) is the main repair pathway for DNA double-strand breaks (DSBs) in cells with limited 5′ resection. To better understand how overhang polarity of chromosomal DSBs affects NHEJ, we made site-specific 5′-overhanging DSBs (5′ DSBs) in yeast using an optimized zinc finger nuclease at an efficiency that approached HO-induced 3′ DSB formation. When controlled for the extent of DSB formation, repair monitoring suggested that chromosomal 5′ DSBs were rejoined more efficiently than 3′ DSBs, consistent with a robust recruitment of NHEJ proteins to 5′ DSBs. Ligation-mediated qPCR revealed that Mre11-Rad50-Xrs2 rapidly modified 5′ DSBs and facilitated protection of 3′ DSBs, likely through recognition of overhang polarity by the Mre11 nuclease. Next-generation sequencing revealed that NHEJ at 5′ DSBs had a higher mutation frequency, and validated the differential requirement of Pol4 polymerase at 3′ and 5′ DSBs. The end processing enzyme Tdp1 did not impact joining fidelity at chromosomal 5′ DSBs as in previous plasmid studies, although Tdp1 was recruited to only 5′ DSBs in a Ku-independent manner. These results suggest distinct DSB handling based on overhang polarity that impacts NHEJ kinetics and fidelity through differential recruitment and action of DSB modifying enzymes.
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Affiliation(s)
- Zhuobin Liang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sham Sunder
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Thomas E Wilson
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
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