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Mesquita A, Glenn J, Jenny A. Differential activation of eMI by distinct forms of cellular stress. Autophagy 2021; 17:1828-1840. [PMID: 32559125 PMCID: PMC8386722 DOI: 10.1080/15548627.2020.1783833] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/03/2020] [Accepted: 06/08/2020] [Indexed: 12/11/2022] Open
Abstract
As one of the major, highly conserved catabolic pathways, autophagy delivers cytosolic components to lysosomes for degradation. It is essential for development, cellular homeostasis, and coping with stress. Reduced autophagy increases susceptibility to protein aggregation diseases and leads to phenotypes associated with aging. Of the three major forms of autophagy, macroautophagy (MA) can degrade organelles or aggregated proteins, and chaperone-mediated autophagy is specific for soluble proteins containing KFERQ-related targeting motifs. During endosomal microautophagy (eMI), cytoplasmic proteins are engulfed into late endosomes in an ESCRT machinery-dependent manner. eMI can be KFERQ-specific or occur in bulk and be induced by prolonged starvation. Its physiological regulation and function, however, are not understood. Here, we show that eMI in the Drosophila fat body, akin to the mammalian liver, is induced upon oxidative or genotoxic stress in an ESCRT and partially Hsc70-4-dependent manner. Interestingly, eMI activation is selective, as ER stress fails to elicit a response. Intriguingly, we find that reducing MA leads to a compensatory enhancement of eMI, suggesting a tight interplay between these degradative processes. Furthermore, we show that mutations in DNA damage response genes are sufficient to trigger eMI and that the response to oxidative stress is under the control of MAPK/JNK signaling. Our data suggest that, controlled by various signaling pathways, eMI allows an organ to react and adapt to specific types of stress and is thus likely critical to prevent disease.Abbreviations:Atg: autophagy-related; CMA: chaperone-mediated autophagy; DDR: DNA damage repair; Df: deficiency (deletion); (E)GFP: (enhanced) green fluorescent protein; eMI: endosomal microautophagy; ER: endoplasmatic reticulum; ESCRT: endosomal sorting complexes required for transport; Eto: etoposide; FLP: flipase; Hsc: heat shock cognate protein; LAMP2A: lysosomal-associated membrane protein 2A; LE: late endosome; MA: macroautophagy; MI: microautophagy; MVB: multivesicular body; PA: photoactivatable; Para: paraquat; ROS: reactive oxygen species; SEM: standard error of means; Tor: target of rapamycin [serine/threonine kinase]; UPR: unfolded protein response; Vps: vacuolar protein sorting.
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Affiliation(s)
- Ana Mesquita
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, New York, NY, US
| | - James Glenn
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, New York, NY, US
| | - Andreas Jenny
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, New York, NY, US
- Department of Genetics, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, New York, NY, US
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine, New York, NY, US
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2
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Sarraf SA, Sideris DP, Giagtzoglou N, Ni L, Kankel MW, Sen A, Bochicchio LE, Huang CH, Nussenzweig SC, Worley SH, Morton PD, Artavanis-Tsakonas S, Youle RJ, Pickrell AM. PINK1/Parkin Influences Cell Cycle by Sequestering TBK1 at Damaged Mitochondria, Inhibiting Mitosis. Cell Rep 2020; 29:225-235.e5. [PMID: 31577952 PMCID: PMC6880866 DOI: 10.1016/j.celrep.2019.08.085] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 05/13/2019] [Accepted: 08/27/2019] [Indexed: 12/21/2022] Open
Abstract
PINK1 and Parkin are established mediators of mitophagy, the selective removal of damaged mitochondria by autophagy. PINK1 and Parkin have been proposed to act as tumor suppressors, as loss-of-function mutations are correlated with enhanced tumorigenesis. However, it is unclear how PINK1 and Parkin act in coordination during mitophagy to influence the cell cycle. Here we show that PINK1 and Parkin genetically interact with proteins involved in cell cycle regulation, and loss of PINK1 and Parkin accelerates cell growth. PINK1- and Parkin-mediated activation of TBK1 at the mitochondria during mitophagy leads to a block in mitosis due to the sequestration of TBK1 from its physiological role at centrosomes during mitosis. Our study supports a diverse role for the far-reaching, regulatory effects of mitochondrial quality control in cellular homeostasis and demonstrates that the PINK1/Parkin pathway genetically interacts with the cell cycle, providing a framework for understanding the molecular basis linking PINK1 and Parkin to mitosis. Sarraf et al. use mouse and fly genetics to discover that PINK1 and Parkin influence cell cycle progression. Mitophagy and mitosis independently activate TBK1 at damaged mitochondria and centrosomes, respectively, influencing whether the cell will address mitochondrial quality control or progress with proliferation.
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Affiliation(s)
- Shireen A Sarraf
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Dionisia P Sideris
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | | | - Lina Ni
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Mark W Kankel
- Neuromuscular & Movement Disorders, Biogen, Inc., Cambridge, MA 02142, USA
| | - Anindya Sen
- Pathway Discovery Laboratory, Biogen, Inc., Cambridge, MA 02142, USA
| | - Lauren E Bochicchio
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, VA 24016, USA
| | - Chiu-Hui Huang
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Samuel C Nussenzweig
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Stuart H Worley
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Paul D Morton
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Spyros Artavanis-Tsakonas
- Pathway Discovery Laboratory, Biogen, Inc., Cambridge, MA 02142, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Richard J Youle
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Alicia M Pickrell
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA; School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
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3
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Kim T, Song B, Lee IS. Drosophila Glia: Models for Human Neurodevelopmental and Neurodegenerative Disorders. Int J Mol Sci 2020; 21:E4859. [PMID: 32660023 PMCID: PMC7402321 DOI: 10.3390/ijms21144859] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/27/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are key players in the proper formation and maintenance of the nervous system, thus contributing to neuronal health and disease in humans. However, little is known about the molecular pathways that govern glia-neuron communications in the diseased brain. Drosophila provides a useful in vivo model to explore the conserved molecular details of glial cell biology and their contributions to brain function and disease susceptibility. Herein, we review recent studies that explore glial functions in normal neuronal development, along with Drosophila models that seek to identify the pathological implications of glial defects in the context of various central nervous system disorders.
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Affiliation(s)
| | | | - Im-Soon Lee
- Department of Biological Sciences, Center for CHANS, Konkuk University, Seoul 05029, Korea; (T.K.); (B.S.)
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4
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Bayer FE, Zimmermann M, Preiss A, Nagel AC. Overexpression of the Drosophila ATR homologous checkpoint kinase Mei-41 induces a G2/M checkpoint in Drosophila imaginal tissue. Hereditas 2018; 155:27. [PMID: 30202398 PMCID: PMC6125995 DOI: 10.1186/s41065-018-0066-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 08/28/2018] [Indexed: 11/25/2022] Open
Abstract
Background DNA damage generally results in the activation of ATM/ATR kinases and the downstream checkpoint kinases Chk1/Chk2. In Drosophila melanogaster, the ATR homologue meiotic 41 (mei-41) is pivotal to DNA damage repair and cell cycle checkpoint signalling. Although various mei-41 mutant alleles have been analyzed in the past, no gain-of-function allele is yet available. To fill this gap, we have generated transgenic flies allowing temporal and tissue-specific induction of mei-41. Results Overexpression of mei-41 in wing and eye anlagen affects proliferation and a G2/M checkpoint even in the absence of genomic stress. Similar consequences were observed following the overexpression of the downstream kinase Grapes (Grp) but not of Loki (Lok), encoding the respective Drosophila Chk1 and Chk2 homologues, in agreement with their previously reported activities. Moreover, we show that irradiation induced cell cycle arrest was prolonged in the presence of ectopic mei-41 expression. Similar to irradiation stress, mei-41 triggered the occurrence of a slower migrating form of Grp, implying specific phosphorylation of Grp in response to either signal. Using a p53R-GFP biosensor, we further show that overexpression of mei-41 was sufficient to elicit a robust p53 activation in vivo. Conclusion We conclude that overexpression of the Drosophila ATR homologue mei-41 elicits an effectual DNA damage response irrespective of irradiation. Electronic supplementary material The online version of this article (10.1186/s41065-018-0066-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Fabienne E Bayer
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
| | - Mirjam Zimmermann
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anette Preiss
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
| | - Anja C Nagel
- Universität Hohenheim, Institut für Genetik, Garbenstr. 30, 70599 Stuttgart, Germany
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Rimkus SA, Wassarman DA. A pharmacological screen for compounds that rescue the developmental lethality of a Drosophila ATM mutant. PLoS One 2018; 13:e0190821. [PMID: 29338042 PMCID: PMC5770031 DOI: 10.1371/journal.pone.0190821] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 12/20/2017] [Indexed: 12/11/2022] Open
Abstract
Ataxia-telangiectasia (A-T) is a neurodegenerative disease caused by mutation of the A-T mutated (ATM) gene. ATM encodes a protein kinase that is activated by DNA damage and phosphorylates many proteins, including those involved in DNA repair, cell cycle control, and apoptosis. Characteristic biological and molecular functions of ATM observed in mammals are conserved in Drosophila melanogaster. As an example, conditional loss-of-function ATM alleles in flies cause progressive neurodegeneration through activation of the innate immune response. However, unlike in mammals, null alleles of ATM in flies cause lethality during development. With the goals of understanding biological and molecular roles of ATM in a whole animal and identifying candidate therapeutics for A-T, we performed a screen of 2400 compounds, including FDA-approved drugs, natural products, and bioactive compounds, for modifiers of the developmental lethality caused by a temperature-sensitive ATM allele (ATM8) that has reduced kinase activity at non-permissive temperatures. Ten compounds reproducibly suppressed the developmental lethality of ATM8 flies, including Ronnel, which is an organophosphate. Ronnel and other suppressor compounds are known to cause mitochondrial dysfunction or to inhibit the enzyme acetylcholinesterase, which controls the levels of the neurotransmitter acetylcholine, suggesting that detrimental consequences of reduced ATM kinase activity can be rescued by inhibiting the function of mitochondria or increasing acetylcholine levels. We carried out further studies of Ronnel because, unlike the other compounds that suppressed the developmental lethality of homozygous ATM8 flies, Ronnel was toxic to the development of heterozygous ATM8 flies. Ronnel did not affect the innate immune response of ATM8 flies, and it further increased the already high levels of DNA damage in brains of ATM8 flies, but its effects were not harmful to the lifespan of rescued ATM8 flies. These results provide new leads for understanding the biological and molecular roles of ATM and for the treatment of A-T.
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Affiliation(s)
- Stacey A. Rimkus
- Department of Medical Genetics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - David A. Wassarman
- Department of Medical Genetics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
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Quek H, Lim YC, Lavin MF, Roberts TL. PIKKing a way to regulate inflammation. Immunol Cell Biol 2017; 96:8-20. [DOI: 10.1111/imcb.1001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/31/2017] [Accepted: 09/02/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Hazel Quek
- The University of Queensland Centre for Clinical Research; Herston Qld Australia
- QIMR Berghofer Medical Research Institute; Herston Qld Australia
| | - Yi Chieh Lim
- QIMR Berghofer Medical Research Institute; Herston Qld Australia
| | - Martin F Lavin
- The University of Queensland Centre for Clinical Research; Herston Qld Australia
| | - Tara L Roberts
- The University of Queensland Centre for Clinical Research; Herston Qld Australia
- The Ingham Institute for Applied Medical Research and School of Medicine; Western Sydney University; Liverpool New South Wales Australia
- South West Sydney Clinical School; Sydney UNSW Australia
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Lee CH, Rimesso G, Reynolds DM, Cai J, Baker NE. Whole-Genome Sequencing and iPLEX MassARRAY Genotyping Map an EMS-Induced Mutation Affecting Cell Competition in Drosophila melanogaster. G3 (BETHESDA, MD.) 2016; 6:3207-3217. [PMID: 27574103 PMCID: PMC5068942 DOI: 10.1534/g3.116.029421] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/04/2016] [Indexed: 01/09/2023]
Abstract
Cell competition, the conditional loss of viable genotypes only when surrounded by other cells, is a phenomenon observed in certain genetic mosaic conditions. We conducted a chemical mutagenesis and screen to recover new mutations that affect cell competition between wild-type and RpS3 heterozygous cells. Mutations were identified by whole-genome sequencing, making use of software tools that greatly facilitate the distinction between newly induced mutations and other sources of apparent sequence polymorphism, thereby reducing false-positive and false-negative identification rates. In addition, we utilized iPLEX MassARRAY for genotyping recombinant chromosomes. These approaches permitted the mapping of a new mutation affecting cell competition when only a single allele existed, with a phenotype assessed only in genetic mosaics, without the benefit of complementation with existing mutations, deletions, or duplications. These techniques expand the utility of chemical mutagenesis and whole-genome sequencing for mutant identification. We discuss mutations in the Atm and Xrp1 genes identified in this screen.
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Affiliation(s)
- Chang-Hyun Lee
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Gerard Rimesso
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - David M Reynolds
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Jinlu Cai
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Nicholas E Baker
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
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A hypomorphic mutation reveals a stringent requirement for the ATM checkpoint protein in telomere protection during early cell division in Drosophila. G3-GENES GENOMES GENETICS 2013; 3:1043-8. [PMID: 23604076 PMCID: PMC3689801 DOI: 10.1534/g3.113.006312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Using Drosophila as a model system, we identified a stringent requirement for the conserved function of Ataxia Telangiectasia Mutated (ATM) in telomere protection during early embryonic development. Animals homozygous for a hypomorphic mutation in atm develop normally with minimal telomere dysfunction. However, mutant females produce inviable embryos that succumb to mitotic failure caused by covalent fusions of telomeric DNA. Interestingly, although the atm mutation encodes a premature stop codon, it must not have eliminated the production of the mutant protein, and the mutant protein retains kinase activity upon DNA damage. Moreover, although the embryonic phenotype of this mutation resembles that of hypomorphic mutations in the MRN complex, the function of MRN appears normal in the atm embryos. In contrast, there is a prominent reduction of the level of HipHop, an essential member of the Drosophila capping complex. How ATM functions in telomere protection remains poorly understood. The amenability of Drosophila embryos to molecular and biochemical investigations ensures that this newly identified mutation will facilitate future studies of ATM in telomere maintenance.
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The innate immune response transcription factor relish is necessary for neurodegeneration in a Drosophila model of ataxia-telangiectasia. Genetics 2013; 194:133-42. [PMID: 23502677 DOI: 10.1534/genetics.113.150854] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurodegeneration is a hallmark of the human disease ataxia-telangiectasia (A-T) that is caused by mutation of the A-T mutated (ATM) gene. We have analyzed Drosophila melanogaster ATM mutants to determine the molecular mechanisms underlying neurodegeneration in A-T. Previously, we found that ATM mutants upregulate the expression of innate immune response (IIR) genes and undergo neurodegeneration in the central nervous system. Here, we present evidence that activation of the IIR is a cause of neurodegeneration in ATM mutants. Three lines of evidence indicate that ATM mutations cause neurodegeneration by activating the Nuclear Factor-κB (NF-κB) transcription factor Relish, a key regulator of the Immune deficiency (Imd) IIR signaling pathway. First, the level of upregulation of IIR genes, including Relish target genes, was directly correlated with the level of neurodegeneration in ATM mutants. Second, Relish mutations inhibited upregulation of IIR genes and neurodegeneration in ATM mutants. Third, overexpression of constitutively active Relish in glial cells activated the IIR and caused neurodegeneration. In contrast, we found that Imd and Dif mutations did not affect neurodegeneration in ATM mutants. Imd encodes an activator of Relish in the response to gram-negative bacteria, and Dif encodes an immune responsive NF-κB transcription factor in the Toll signaling pathway. These data indicate that the signal that causes neurodegeneration in ATM mutants activates a specific NF-κB protein and does so through an unknown activator. In summary, these findings suggest that neurodegeneration in human A-T is caused by activation of a specific NF-κB protein in glial cells.
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Petersen AJ, Wassarman DA. Drosophila innate immune response pathways moonlight in neurodegeneration. Fly (Austin) 2012; 6:169-72. [PMID: 22864563 DOI: 10.4161/fly.20999] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In this Extra View, we highlight recent Drosophila research that has uncovered a new role for the innate immune response. The research indicates that, in addition to combating infection, the innate immune response promotes neurodegeneration. Our publication (Petersen et al., 2012) reveals a correlative relationship between the innate immune response and neurodegeneration in a model of the human disease Ataxia-telangiectasia (A-T). We also found that glial cells are responsible for the innate immune response in the A-T model, and work by others implicates glial cells in neurodegeneration. Additionally, publications by Chinchore et al. (2012) and Tan et al. (2008) reveal a causative role for the innate immune response in models of human retinal degenerative disorders and Alzheimer disease, respectively. Collectively, these findings suggest that activation of the innate immune response is a shared cause of neurodegeneration in different human diseases.
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Affiliation(s)
- Andrew J Petersen
- Molecular and Cellular Pharmacology Program, University of Wisconsin School of Medicine and Public Health, Madison, WI USA
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ATM kinase inhibition in glial cells activates the innate immune response and causes neurodegeneration in Drosophila. Proc Natl Acad Sci U S A 2012; 109:E656-64. [PMID: 22355133 DOI: 10.1073/pnas.1110470109] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
To investigate the mechanistic basis for central nervous system (CNS) neurodegeneration in the disease ataxia-telangiectasia (A-T), we analyzed flies mutant for the causative gene A-T mutated (ATM). ATM encodes a protein kinase that functions to monitor the genomic integrity of cells and control cell cycle, DNA repair, and apoptosis programs. Mutation of the C-terminal amino acid in Drosophila ATM inhibited the kinase activity and caused neuron and glial cell death in the adult brain and a reduction in mobility and longevity. These data indicate that reduced ATM kinase activity is sufficient to cause neurodegeneration in A-T. ATM kinase mutant flies also had elevated expression of innate immune response genes in glial cells. ATM knockdown in glial cells, but not neurons, was sufficient to cause neuron and glial cell death, a reduction in mobility and longevity, and elevated expression of innate immune response genes in glial cells, indicating that a non-cell-autonomous mechanism contributes to neurodegeneration in A-T. Taken together, these data suggest that early-onset CNS neurodegeneration in A-T is similar to late-onset CNS neurodegeneration in diseases such as Alzheimer's in which uncontrolled inflammatory response mediated by glial cells drives neurodegeneration.
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Joyce EF, Pedersen M, Tiong S, White-Brown SK, Paul A, Campbell SD, McKim KS. Drosophila ATM and ATR have distinct activities in the regulation of meiotic DNA damage and repair. ACTA ACUST UNITED AC 2011; 195:359-67. [PMID: 22024169 PMCID: PMC3206348 DOI: 10.1083/jcb.201104121] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Ataxia telangiectasia-mutated (ATM) and ataxia telangiectasia-related (ATR) kinases are conserved regulators of cellular responses to double strand breaks (DSBs). During meiosis, however, the functions of these kinases in DSB repair and the deoxyribonucleic acid (DNA) damage checkpoint are unclear. In this paper, we show that ATM and ATR have unique roles in the repair of meiotic DSBs in Drosophila melanogaster. ATR mutant analysis indicated that it is required for checkpoint activity, whereas ATM may not be. Both kinases phosphorylate H2AV (γ-H2AV), and, using this as a reporter for ATM/ATR activity, we found that the DSB repair response is surprisingly dynamic at the site of DNA damage. γ-H2AV is continuously exchanged, requiring new phosphorylation at the break site until repair is completed. However, most surprising is that the number of γ-H2AV foci is dramatically increased in the absence of ATM, but not ATR, suggesting that the number of DSBs is increased. Thus, we conclude that ATM is primarily required for the meiotic DSB repair response, which includes functions in DNA damage repair and negative feedback control over the level of programmed DSBs during meiosis.
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Affiliation(s)
- Eric F Joyce
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ 08854, USA
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