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Karlowicz A, Dubiel AB, Czerwinska J, Bledea A, Purzycki P, Grzelewska M, McAuley RJ, Szczesny RJ, Brzuska G, Krol E, Szczesny B, Szymanski MR. In vitro reconstitution reveals a key role of human mitochondrial EXOG in RNA primer processing. Nucleic Acids Res 2022; 50:7991-8007. [PMID: 35819194 PMCID: PMC9371904 DOI: 10.1093/nar/gkac581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 06/01/2022] [Accepted: 06/24/2022] [Indexed: 11/12/2022] Open
Abstract
The removal of RNA primers is essential for mitochondrial DNA (mtDNA) replication. Several nucleases have been implicated in RNA primer removal in human mitochondria, however, no conclusive mechanism has been elucidated. Here, we reconstituted minimal in vitro system capable of processing RNA primers into ligatable DNA ends. We show that human 5'-3' exonuclease, EXOG, plays a fundamental role in removal of the RNA primer. EXOG cleaves short and long RNA-containing flaps but also in cooperation with RNase H1, processes non-flap RNA-containing intermediates. Our data indicate that the enzymatic activity of both enzymes is necessary to process non-flap RNA-containing intermediates and that regardless of the pathway, EXOG-mediated RNA cleavage is necessary prior to ligation by DNA Ligase III. We also show that upregulation of EXOG levels in mitochondria increases ligation efficiency of RNA-containing substrates and discover physical interactions, both in vitro and in cellulo, between RNase H1 and EXOG, Pol γA, Pol γB and Lig III but not FEN1, which we demonstrate to be absent from mitochondria of human lung epithelial cells. Together, using human mtDNA replication enzymes, we reconstitute for the first time RNA primer removal reaction and propose a novel model for RNA primer processing in human mitochondria.
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Affiliation(s)
- Anna Karlowicz
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Andrzej B Dubiel
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Jolanta Czerwinska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego 5A, 02-106 Warsaw, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Warsaw 02-106, Poland
| | - Adela Bledea
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Piotr Purzycki
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Marta Grzelewska
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Ryan J McAuley
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Roman J Szczesny
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, ul. Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Gabriela Brzuska
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Ewelina Krol
- Laboratory of Recombinant Vaccines, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
| | - Bartosz Szczesny
- Department of Ophthalmology and Visual Sciences, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Michal R Szymanski
- Structural Biology Laboratory, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, University of Gdansk, ul. Abrahama 58, 80-307 Gdansk, Poland
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Saada J, McAuley RJ, Marcatti M, Tang TZ, Motamedi M, Szczesny B. Oxidative stress induces Z-DNA-binding protein 1-dependent activation of microglia via mtDNA released from retinal pigment epithelial cells. J Biol Chem 2022; 298:101523. [PMID: 34953858 PMCID: PMC8753185 DOI: 10.1016/j.jbc.2021.101523] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/17/2021] [Accepted: 12/19/2021] [Indexed: 11/28/2022] Open
Abstract
Oxidative stress, inflammation, and aberrant activation of microglia in the retina are commonly observed in ocular pathologies. In glaucoma or age-related macular degeneration, the chronic activation of microglia affects retinal ganglion cells and photoreceptors, respectively, contributing to gradual vision loss. However, the molecular mechanisms that cause activation of microglia in the retina are not fully understood. Here we show that exposure of retinal pigment epithelial (RPE) cells to chronic low-level oxidative stress induces mitochondrial DNA (mtDNA)-specific damage, and the subsequent translocation of damaged mtDNA to the cytoplasm results in the binding and activation of intracellular DNA receptor Z-DNA-binding protein 1 (ZBP1). Activation of the mtDNA/ZBP1 pathway triggers the expression of proinflammatory markers in RPE cells. In addition, we show that the enhanced release of extracellular vesicles (EVs) containing fragments of mtDNA derived from the apical site of RPE cells induces a proinflammatory phenotype of microglia via activation of ZBP1 signaling. Collectively, our report establishes oxidatively damaged mtDNA as an important signaling molecule with ZBP1 as its intracellular receptor in the development of an inflammatory response in the retina. We propose that this novel mtDNA-mediated autocrine and paracrine mechanism for triggering and maintaining inflammation in the retina may play an important role in ocular pathologies. Therefore, the molecular mechanisms identified in this report are potentially suitable therapeutic targets to ameliorate development of ocular pathologies.
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Affiliation(s)
- Jamal Saada
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, USA; Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Ryan J McAuley
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, USA
| | - Michela Marcatti
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas, USA; Department of Neurology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Tony Zifeng Tang
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, Texas, USA
| | - Massoud Motamedi
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| | - Bartosz Szczesny
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, Texas, USA; Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas, USA.
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3
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PGC-1ɑ Mediated-EXOG, a Specific Repair Enzyme for Mitochondrial DNA, Plays an Essential Role in the Rotenone-Induced Neurotoxicity of PC12 Cells. J Mol Neurosci 2021; 71:2336-2352. [PMID: 33515431 DOI: 10.1007/s12031-020-01775-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/10/2020] [Indexed: 10/22/2022]
Abstract
Mitochondria harbor small circular genomes (mtDNA) that encode 13 oxidative phosphorylation (OXPHOS) proteins, and types of damage to mtDNA may contribute to neuronal damage. Recent studies suggested that regulation of mtDNA repair proteins may be a potential strategy for treating neuronal damage. The mtDNA repair system contains its own repair enzymes and is independent from the nuclear DNA repair system. Endo/exonuclease G-like(EXOG) is a mitochondria-specific 5-exo/endonuclease required for repairing endogenous single-strand breaks (SSBs) in mtDNA. However, whether EXOG plays a key role in neuronal damage induced by rotenone remains unknown. Thus, in this study, we aimed to investigate the effect of EXOG on mtDNA repair and mitochondrial functional maintenance in rotenone-induced neurotoxicity. Our results indicated that rotenone influenced the expression and location of EXOG in PC12 cells. Meanwhile, after rotenone exposure, the expression was reduced for proteins responsible for mtDNA repair, including DNA polymerase γ (POLG), high-temperature requirement protease A2 (HtrA2), and the heat-shock factor 1-single-stranded DNA-binding protein 1 (HSF1-SSBP1) complex. Further analysis demonstrated that EXOG knockdown led to reduced mtDNA copy number and mtDNA transcript level and increased mtDNA deletion, which further aggravated the mtDNA damage and mitochondrial dysfunction under rotenone stress. In turn, EXOG overexpression protected PC12 cells from mtDNA damage and mitochondrial dysfunction induced by rotenone. As a result, EXOG knockdown reduced cell viability and tyrosine hydroxylase expression, while EXOG overexpression alleviated rotenone's effect on cell viability and tyrosine hydroxylase expression in PC12 cells. Further, we observed that EXOG influenced mtDNA repair by regulating protein expression of the HSF1-SSBP1 complex and POLG. Furthermore, our study showed that PGC-1α upregulation with ZLN005 led to increased protein levels of EXOG, POLG, HSF1, and SSBP1, all of which contribute to mtDNA homeostasis. Therefore, PGC-1α may be involved in mtDNA repair through interacting with multiple mtDNA repair proteins, especially with the help of EXOG. In summary, EXOG regulation by PGC-1α plays an essential role in rotenone-induced neurotoxicity in PC12 cells. EXOG represents a protective effect strategy in PC12 cells exposed to rotenone.
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Matkarimov BT, Saparbaev MK. DNA Repair and Mutagenesis in Vertebrate Mitochondria: Evidence for Asymmetric DNA Strand Inheritance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1241:77-100. [DOI: 10.1007/978-3-030-41283-8_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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5
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Wu CC, Lin JL, Yang-Yen HF, Yuan HS. A unique exonuclease ExoG cleaves between RNA and DNA in mitochondrial DNA replication. Nucleic Acids Res 2019; 47:5405-5419. [PMID: 30949702 PMCID: PMC6547421 DOI: 10.1093/nar/gkz241] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/13/2019] [Accepted: 03/25/2019] [Indexed: 01/01/2023] Open
Abstract
Replication of sufficient mitochondrial DNA (mtDNA) is essential for maintaining mitochondrial functions in mammalian cells. During mtDNA replication, RNA primers must be removed before the nascent circular DNA strands rejoin. This process involves mitochondrial RNase H1, which removes most of the RNA primers but leaves two ribonucleotides attached to the 5′ end of nascent DNA. A subsequent 5′-exonuclease is required to remove the residual ribonucleotides, however, it remains unknown if any mitochondrial 5′-exonuclease could remove two RNA nucleotides from a hybrid duplex DNA. Here, we report that human mitochondrial Exonuclease G (ExoG) may participate in this particular process by efficiently cleaving at RNA–DNA junctions to remove the 5′-end RNA dinucleotide in an RNA/DNA hybrid duplex. Crystal structures of human ExoG bound respectively with DNA, RNA/DNA hybrid and RNA–DNA chimeric duplexes uncover the underlying structural mechanism of how ExoG specifically recognizes and cleaves at RNA–DNA junctions of a hybrid duplex with an A-form conformation. This study hence establishes the molecular basis of ExoG functioning as a unique 5′-exonuclease to mediate the flap-independent RNA primer removal process during mtDNA replication to maintain mitochondrial genome integrity.
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Affiliation(s)
- Chyuan-Chuan Wu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Jason L J Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Hsin-Fang Yang-Yen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Hanna S Yuan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC
- Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan 10048, ROC
- To whom correspondence should be addressed. Tel: +886 2 27884151;
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Addinsall AB, Martin SD, Collier F, Conlan XA, Foletta VC, Stupka N. Differential regulation of cellular stress responses by the endoplasmic reticulum-resident Selenoprotein S (Seps1) in proliferating myoblasts versus myotubes. Physiol Rep 2018; 6:e13926. [PMID: 30557449 PMCID: PMC6296459 DOI: 10.14814/phy2.13926] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 01/03/2023] Open
Abstract
The antioxidant Selenoprotein S (Seps1, Selenos) is an endoplasmic reticulum (ER)-resident protein associated with metabolic and inflammatory disease. While Seps1 is highly expressed in skeletal muscle, its mechanistic role as an antioxidant in skeletal muscle cells is not well characterized. In C2C12 myotubes treated with palmitate for 24 h, endogenous Seps1 protein expression was upregulated twofold. Two different siRNA constructs were used to investigate whether decreased levels of Seps1 exacerbated lipid-induced oxidative and ER stress in C2C12 myotubes and myoblasts, which differ with regards to cell cycle state and metabolic phenotype. In myoblasts, Seps1 protein knockdown of ~50% or ~75% exacerbated cellular stress responses in the presence of palmitate; as indicated by decreased cell viability and proliferation, higher H2 O2 levels, a lower reduced to oxidized glutathione (GSH:GSSG) ratio, and enhanced gene expression of ER and oxidative stress markers. Even in the absence of palmitate, Seps1 knockdown increased oxidative stress in myoblasts. Whereas, in myotubes in the presence of palmitate, a ~50% knockdown of Seps1 was associated with a trend toward a marginal (3-5%) decrease in viability (P = 0.05), decreased cellular ROS levels, and a reduced mRNA transcript abundance of the cellular stress marker thioredoxin inhibitory binding protein (Txnip). Furthermore, no enhancement of gene markers of ER stress was observed in palmitate-treated myotubes in response to Seps1 knockdown. In conclusion, reduced Seps1 levels exacerbate nutrient-induced cellular stress responses to a greater extent in glycolytic, proliferating myoblasts than in oxidative, differentiated myotubes, thus demonstrating the importance of cell phenotype to Seps1 function.
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Affiliation(s)
- Alex B. Addinsall
- Centre for Molecular and Medical ResearchSchool of MedicineDeakin UniversityGeelongAustralia
| | - Sheree D. Martin
- Centre for Molecular and Medical ResearchSchool of MedicineDeakin UniversityGeelongAustralia
| | - Fiona Collier
- GCEID, University HospitalBarwon HealthGeelongAustralia
- School of MedicineDeakin UniversityGeelongAustralia
| | - Xavier A. Conlan
- Centre for Chemistry and BiotechnologySchool of Life and Environmental SciencesFaculty of Science, Engineering and Built EnvironmentDeakin UniversityGeelongAustralia
| | - Victoria C. Foletta
- Institute for Physical Activity and Nutrition (IPAN)School of Exercise and Nutrition SciencesDeakin UniversityGeelongAustralia
| | - Nicole Stupka
- Centre for Molecular and Medical ResearchSchool of MedicineDeakin UniversityGeelongAustralia
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Razak AM, Khor SC, Jaafar F, Karim NA, Makpol S. Targeting myomiRs by tocotrienol-rich fraction to promote myoblast differentiation. GENES AND NUTRITION 2018; 13:31. [PMID: 30519366 PMCID: PMC6267085 DOI: 10.1186/s12263-018-0618-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 11/05/2018] [Indexed: 11/10/2022]
Abstract
Background Several muscle-specific microRNAs (myomiRs) are differentially expressed during cellular senescence. However, the role of dietary compounds on myomiRs remains elusive. This study aimed to elucidate the modulatory role of tocotrienol-rich fraction (TRF) on myomiRs and myogenic genes during differentiation of human myoblasts. Young and senescent human skeletal muscle myoblasts (HSMM) were treated with 50 μg/mL TRF for 24 h before and after inducing differentiation. Results The fusion index and myotube surface area were higher (p < 0.05) on days 3 and 5 than that on day 1 of differentiation. Ageing reduced the differentiation rate, as observed by a decrease in both fusion index and myotube surface area in senescent cells (p < 0.05). Treatment with TRF significantly increased differentiation at days 1, 3 and 5 of young and senescent myoblasts. In senescent myoblasts, TRF increased the expression of miR-206 and miR-486 and decreased PTEN and PAX7 expression. However, the expression of IGF1R was upregulated during early differentiation and decreased at late differentiation when treated with TRF. In young myoblasts, TRF promoted differentiation by modulating the expression of miR-206, which resulted in the reduction of PAX7 expression and upregulation of IGF1R. Conclusion TRF can potentially promote myoblast differentiation by modulating the expression of myomiRs, which regulate the expression of myogenic genes.
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Affiliation(s)
- Azraul Mumtazah Razak
- Department of Biochemistry, Faculty of Medicine, Level 17, Preclinical Building, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaakob Latif, Bandar Tun Razak, Cheras, 56000 Kuala Lumpur, Malaysia
| | - Shy Cian Khor
- Department of Biochemistry, Faculty of Medicine, Level 17, Preclinical Building, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaakob Latif, Bandar Tun Razak, Cheras, 56000 Kuala Lumpur, Malaysia
| | - Faizul Jaafar
- Department of Biochemistry, Faculty of Medicine, Level 17, Preclinical Building, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaakob Latif, Bandar Tun Razak, Cheras, 56000 Kuala Lumpur, Malaysia
| | - Norwahidah Abdul Karim
- Department of Biochemistry, Faculty of Medicine, Level 17, Preclinical Building, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaakob Latif, Bandar Tun Razak, Cheras, 56000 Kuala Lumpur, Malaysia
| | - Suzana Makpol
- Department of Biochemistry, Faculty of Medicine, Level 17, Preclinical Building, Universiti Kebangsaan Malaysia Medical Centre (UKMMC), Jalan Yaakob Latif, Bandar Tun Razak, Cheras, 56000 Kuala Lumpur, Malaysia
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8
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Hurtado-Bagès S, Guberovic I, Buschbeck M. The MacroH2A1.1 - PARP1 Axis at the Intersection Between Stress Response and Metabolism. Front Genet 2018; 9:417. [PMID: 30356649 PMCID: PMC6189284 DOI: 10.3389/fgene.2018.00417] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/06/2018] [Indexed: 12/12/2022] Open
Abstract
The exchange of replication-coupled canonical histones by histone variants endows chromatin with specific features. The replacement of the canonical H2A histone for the histone variant macroH2A is one of the most remarkable epigenetic modifications. The three vertebrate macroH2A proteins have a unique tripartite structure consisting of H2A-like domain, unstructured linker, and macrodomain. Macrodomains are ancient globular folds that are able to bind nicotinamide adenine dinucleotide (NAD+) derived metabolites. Here, we will briefly describe the physiological relevance of the metabolite binding in the context of chromatin. In particular, we will focus on the macroH2A1.1 isoform that binds ADP-ribose and poly-ADP-ribose polymerase 1 (PARP1) enzyme, a cellular stress sensor. We will discuss the impact of this interaction in the context of cancer, senescence, cell stress and energy metabolism.
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Affiliation(s)
- Sarah Hurtado-Bagès
- Josep Carreras Leukaemia Research Institute, Campus ICO-Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.,Ph.D. Program in Biomedicine, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Iva Guberovic
- Josep Carreras Leukaemia Research Institute, Campus ICO-Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.,Ph.D. Program in Biomedicine, Faculty of Pharmacy and Food Science, University of Barcelona, Barcelona, Spain
| | - Marcus Buschbeck
- Josep Carreras Leukaemia Research Institute, Campus ICO-Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.,Program for Predictive and Personalized Medicine of Cancer, Germans Trias i Pujol Research Institute (PMPPC-IGTP), Badalona, Spain
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9
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Bak DH, Na J, Im SI, Oh CT, Kim JY, Park SK, Han HJ, Seok J, Choi SY, Ko EJ, Mun SK, Ahn SW, Kim BJ. Antioxidant effect of human placenta hydrolysate against oxidative stress on muscle atrophy. J Cell Physiol 2018; 234:1643-1658. [PMID: 30132871 DOI: 10.1002/jcp.27034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 06/25/2018] [Indexed: 01/07/2023]
Abstract
Sarcopenia, which refers to the muscle loss that accompanies aging, is a complex neuromuscular disorder with a clinically high prevalence and mortality. Despite many efforts to protect against muscle weakness and muscle atrophy, the incidence of sarcopenia and its related permanent disabilities continue to increase. In this study, we found that treatment with human placental hydrolysate (hPH) significantly increased the viability (approximately 15%) of H2 O2 -stimulated C2C12 cells. Additionally, while H2 O2 -stimulated cells showed irregular morphology, hPH treatment restored their morphology to that of cells cultured under normal conditions. We further showed that hPH treatment effectively inhibited H2 O2 -induced cell death. Reactive oxygen species (ROS) generation and Mstn expression induced by oxidative stress are closely associated with muscular dysfunction followed by atrophy. Exposure of C2C12 cells to H2 O2 induced abundant production of intracellular ROS, mitochondrial superoxide, and mitochondrial dysfunction as well as myostatin expression via nuclear factor-κB (NF-κB) signaling; these effects were attenuated by hPH. Additionally, hPH decreased mitochondria fission-related gene expression (Drp1 and BNIP3) and increased mitochondria biogenesis via the Sirt1/AMPK/PGC-1α pathway and autophagy regulation. In vivo studies revealed that hPH-mediated prevention of atrophy was achieved predominantly through regulation of myostatin and PGC-1α expression and autophagy. Taken together, our findings indicate that hPH is potentially protective against muscle atrophy and oxidative cell death.
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Affiliation(s)
- Dong-Ho Bak
- Department of Dermatology, College of Medicine, Chung-Ang University, Seoul, Korea.,Department of Medicine, Graduate School, Chung-Ang University, Seoul, Korea
| | - Jungtae Na
- Department of Dermatology, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Song I Im
- Department of Dermatology, College of Medicine, Chung-Ang University, Seoul, Korea.,Department of Medicine, Graduate School, Chung-Ang University, Seoul, Korea
| | - Chang Taek Oh
- Research Institute, Research & Development Center, Green Cross WellBeing Corporation, Seongnam, Korea
| | - Jeom-Yong Kim
- Research Institute, Research & Development Center, Green Cross WellBeing Corporation, Seongnam, Korea
| | - Sun-Kyu Park
- Research Institute, Research & Development Center, Green Cross WellBeing Corporation, Seongnam, Korea
| | - Hae Jung Han
- Research Institute, Research & Development Center, Green Cross WellBeing Corporation, Seongnam, Korea
| | - Joon Seok
- Department of Dermatology, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Sun Young Choi
- Department of Dermatology, College of Medicine, Seoul Paik Hospital Inje University, Seoul, Korea
| | - Eun Jung Ko
- Myongji Hospital, College of Medicine, Seonam University, Goyang, Korea
| | - Seog-Kyun Mun
- Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Suk-Won Ahn
- Department of Neurology, College of Medicine, Chung-Ang University, Seoul, Korea
| | - Beom Joon Kim
- Department of Dermatology, College of Medicine, Chung-Ang University, Seoul, Korea.,Department of Medicine, Graduate School, Chung-Ang University, Seoul, Korea
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10
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Dhar SK, Bakthavatchalu V, Dhar B, Chen J, Tadahide I, Zhu H, Gao T, St Clair DK. DNA polymerase gamma (Polγ) deficiency triggers a selective mTORC2 prosurvival autophagy response via mitochondria-mediated ROS signaling. Oncogene 2018; 37:6225-6242. [PMID: 30038268 PMCID: PMC6265263 DOI: 10.1038/s41388-018-0404-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 04/30/2018] [Accepted: 06/11/2018] [Indexed: 11/24/2022]
Abstract
Autophagy is a highly regulated evolutionarily conserved metabolic process induced by stress and energy deprivation. Here, we show that DNA polymerase gamma (Polγ) deficiency activates a selective prosurvival autophagic response via mitochondria-mediated reactive oxygen species (ROS) signaling and the mammalian target of rapamycin complex 2 (mTORC2) activities. In keratinocytes, Polγ deficiency causes metabolic adaptation that triggers cytosolic sensing of energy demand for survival. Knockdown of Polγ causes mitochondrial stress, decreases mitochondrial energy production, increases glycolysis, increases the expression of autophagy-associated genes, and enhances AKT phosphorylation and cell proliferation. Deficiency of Polγ preferentially activates mTORC2 formation to increase autophagy and cell proliferation, and knocking down Rictor abrogates these responses. Overexpression of Rictor, but not Raptor, reactivates autophagy in Polγ-deficient cells. Importantly, inhibition of ROS by a mitochondria-selective ROS scavenger abolishes autophagy and cell proliferation. These results identify Rictor as a critical link between mitochondrial stress, ROS, and autophagy. They represent a major shift in our understanding of the prosurvival role of the mTOR complexes and highlight mitochondria-mediated ROS as a prosurvival autophagy regulator during cancer development.
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Affiliation(s)
- Sanjit K Dhar
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Vasudevan Bakthavatchalu
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Bithika Dhar
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Jing Chen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA
| | - Izumi Tadahide
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, 40536, USA
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA
| | - Tianyan Gao
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA
| | - Daret K St Clair
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, 40536, USA.
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11
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Tigchelaar W, De Jong AM, van Gilst WH, De Boer RA, Silljé HHW. In EXOG-depleted cardiomyocytes cell death is marked by a decreased mitochondrial reserve capacity of the electron transport chain. Bioessays 2017; 38 Suppl 1:S136-45. [PMID: 27417117 DOI: 10.1002/bies.201670914] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 01/13/2016] [Accepted: 01/20/2016] [Indexed: 11/10/2022]
Abstract
Depletion of mitochondrial endo/exonuclease G-like (EXOG) in cultured neonatal cardiomyocytes stimulates mitochondrial oxygen consumption rate (OCR) and induces hypertrophy via reactive oxygen species (ROS). Here, we show that neurohormonal stress triggers cell death in endo/exonuclease G-like-depleted cells, and this is marked by a decrease in mitochondrial reserve capacity. Neurohormonal stimulation with phenylephrine (PE) did not have an additive effect on the hypertrophic response induced by endo/exonuclease G-like depletion. Interestingly, PE-induced atrial natriuretic peptide (ANP) gene expression was completely abolished in endo/exonuclease G-like-depleted cells, suggesting a reverse signaling function of endo/exonuclease G-like. Endo/exonuclease G-like depletion initially resulted in increased mitochondrial OCR, but this declined upon PE stimulation. In particular, the reserve capacity of the mitochondrial respiratory chain and maximal respiration were the first indicators of perturbations in mitochondrial respiration, and these marked the subsequent decline in mitochondrial function. Although pathological stimulation accelerated these processes, prolonged EXOG depletion also resulted in a decline in mitochondrial function. At early stages of endo/exonuclease G-like depletion, mitochondrial ROS production was increased, but this did not affect mitochondrial DNA (mtDNA) integrity. After prolonged depletion, ROS levels returned to control values, despite hyperpolarization of the mitochondrial membrane. The mitochondrial dysfunction finally resulted in cell death, which appears to be mainly a form of necrosis. In conclusion, endo/exonuclease G-like plays an essential role in cardiomyocyte physiology. Loss of endo/exonuclease G-like results in diminished adaptation to pathological stress. The decline in maximal respiration and reserve capacity is the first sign of mitochondrial dysfunction that determines subsequent cell death.
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Affiliation(s)
- Wardit Tigchelaar
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Anne Margreet De Jong
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Wiek H van Gilst
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Rudolf A De Boer
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Herman H W Silljé
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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12
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Salucci S, Battistelli M, Baldassarri V, Burini D, Falcieri E, Burattini S. Melatonin prevents mitochondrial dysfunctions and death in differentiated skeletal muscle cells. Microsc Res Tech 2017; 80:1174-1181. [PMID: 28742227 DOI: 10.1002/jemt.22914] [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] [Received: 06/27/2017] [Accepted: 07/08/2017] [Indexed: 12/24/2022]
Abstract
Oxidative stress increase induces cellular damage and apoptosis activation, a mechanism believed to represent a final common pathway correlated to sarcopenia and many skeletal muscle disorders. The goal of this study is to evaluate if melatonin, a ROS scavenger molecule, is able to counteract or modulate myotube death. Here, differentiated C2C12 skeletal muscle cells have been treated with melatonin before chemicals known to induce apoptotic death and oxidative stress, and its effect has been investigated by means of morpho-functional analyses. Ultrastructural observations show melatonin protection against triggers by the reducing of membrane blebbing, chromatin condensation, myonuclei loss and in situ DNA cleavage. Moreover, melatonin is able to prevent mitochondrial dysfunctions which occur in myotubes exposed to the trigger alone. These findings demonstrate melatonin ability in preventing apoptotic cell death in skeletal muscle fibers in vitro, suggesting for this molecule a potential therapeutic role in the treatment of various muscle disorders.
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Affiliation(s)
- Sara Salucci
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, Urbino, 61029, Italy
| | - Michela Battistelli
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, Urbino, 61029, Italy
| | - Valentina Baldassarri
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, Urbino, 61029, Italy
| | - Debora Burini
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, Urbino, 61029, Italy
| | - Elisabetta Falcieri
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, Urbino, 61029, Italy
| | - Sabrina Burattini
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Via Saffi 2, Urbino, 61029, Italy
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13
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Caston RA, Demple B. Risky repair: DNA-protein crosslinks formed by mitochondrial base excision DNA repair enzymes acting on free radical lesions. Free Radic Biol Med 2017; 107:146-150. [PMID: 27867099 PMCID: PMC5815828 DOI: 10.1016/j.freeradbiomed.2016.11.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/11/2016] [Accepted: 11/13/2016] [Indexed: 01/06/2023]
Abstract
Oxygen is both necessary and dangerous for aerobic cell function. ATP is most efficiently made by the electron transport chain, which requires oxygen as an electron acceptor. However, the presence of oxygen, and to some extent the respiratory chain itself, poses a danger to cellular components. Mitochondria, the sites of oxidative phosphorylation, have defense and repair pathways to cope with oxidative damage. For mitochondrial DNA, an essential pathway is base excision repair, which acts on a variety of small lesions. There are instances, however, in which attempted DNA repair results in more damage, such as the formation of a DNA-protein crosslink trapping the repair enzyme on the DNA. That is the case for mitochondrial DNA polymerase γ acting on abasic sites oxidized at the 1-carbon of 2-deoxyribose. Such DNA-protein crosslinks presumably must be removed in order to restore function. In nuclear DNA, ubiquitylation of the crosslinked protein and digestion by the proteasome are essential first processing steps. How and whether such mechanisms operate on DNA-protein crosslinks in mitochondria remains to be seen.
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Affiliation(s)
- Rachel Audrey Caston
- Department of Pharmacological Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Bruce Demple
- Department of Pharmacological Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA.
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14
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A domain in human EXOG converts apoptotic endonuclease to DNA-repair exonuclease. Nat Commun 2017; 8:14959. [PMID: 28466855 PMCID: PMC5418593 DOI: 10.1038/ncomms14959] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/16/2017] [Indexed: 11/09/2022] Open
Abstract
Human EXOG (hEXOG) is a 5′-exonuclease that is crucial for mitochondrial DNA repair; the enzyme belongs to a nonspecific nuclease family that includes the apoptotic endonuclease EndoG. Here we report biochemical and structural studies of hEXOG, including structures in its apo form and in a complex with DNA at 1.81 and 1.85 Å resolution, respectively. A Wing domain, absent in other ββα-Me members, suppresses endonuclease activity, but confers on hEXOG a strong 5′-dsDNA exonuclease activity that precisely excises a dinucleotide using an intrinsic ‘tape-measure'. The symmetrical apo hEXOG homodimer becomes asymmetrical upon binding to DNA, providing a structural basis for how substrate DNA bound to one active site allosterically regulates the activity of the other. These properties of hEXOG suggest a pathway for mitochondrial BER that provides an optimal substrate for subsequent gap-filling synthesis by DNA polymerase γ. Human EXOG is crucial for mitochondrial DNA repair. Here the authors present the crystal structures of hEXOG in apo form and as DNA complex and suggest a `tape-measure' activity to generate optimal substrates for mitochondrial base excision repair.
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15
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Tocotrienol-Rich Fraction Ameliorates Antioxidant Defense Mechanisms and Improves Replicative Senescence-Associated Oxidative Stress in Human Myoblasts. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:3868305. [PMID: 28243354 PMCID: PMC5294752 DOI: 10.1155/2017/3868305] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/22/2016] [Accepted: 12/18/2016] [Indexed: 12/16/2022]
Abstract
During aging, oxidative stress affects the normal function of satellite cells, with consequent regeneration defects that lead to sarcopenia. This study aimed to evaluate tocotrienol-rich fraction (TRF) modulation in reestablishing the oxidative status of myoblasts during replicative senescence and to compare the effects of TRF with other antioxidants (α-tocopherol (ATF) and N-acetyl-cysteine (NAC)). Primary human myoblasts were cultured to young, presenescent, and senescent phases. The cells were treated with antioxidants for 24 h, followed by the assessment of free radical generation, lipid peroxidation, antioxidant enzyme mRNA expression and activities, and the ratio of reduced to oxidized glutathione. Our data showed that replicative senescence increased reactive oxygen species (ROS) generation and lipid peroxidation in myoblasts. Treatment with TRF significantly diminished ROS production and decreased lipid peroxidation in senescent myoblasts. Moreover, the gene expression of superoxide dismutase (SOD2), catalase (CAT), and glutathione peroxidase (GPX1) was modulated by TRF treatment, with increased activity of superoxide dismutase and catalase and reduced glutathione peroxidase in senescent myoblasts. In comparison to ATF and NAC, TRF was more efficient in heightening the antioxidant capacity and reducing free radical insults. These results suggested that TRF is able to ameliorate antioxidant defense mechanisms and improves replicative senescence-associated oxidative stress in myoblasts.
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16
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Lee MH, Han MH, Lee DS, Park C, Hong SH, Kim GY, Hong SH, Song KS, Choi IW, Cha HJ, Choi YH. Morin exerts cytoprotective effects against oxidative stress in C2C12 myoblasts via the upregulation of Nrf2-dependent HO-1 expression and the activation of the ERK pathway. Int J Mol Med 2016; 39:399-406. [PMID: 28035409 DOI: 10.3892/ijmm.2016.2837] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 12/08/2016] [Indexed: 12/18/2022] Open
Abstract
In the present study, we investigated the cytoprotective efficacy of morin, a natural flavonoid, against oxidative stress and elucidated the underlying mechanisms in C2C12 myoblasts. Our results indicated that morin treatment prior to hydrogen peroxide (H2O2) exposure significantly increased cell viability and prevented the generation of reactive oxygen species. H2O2-induced comet-like DNA formation and γH2AX phosphorylation were also markedly suppressed by morin with a parallel inhibition of apoptosis in C2C12 myoblasts, suggesting that morin prevented H2O2-induced cellular DNA damage. Furthermore, morin markedly enhanced the expression of heme oxygenase-1 (HO-1) associated with the induction and phosphorylation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and the inhibition of Kelch-like ECH-associated protein 1 (Keap1) expression. Notably, these events were eliminated by transient transfection with Nrf2‑specific small interfering RNA. Additional experiments demonstrated that the activation of the Nrf2/HO-1 pathway by morin was mediated by the extracellular signal‑regulated kinase (ERK) signaling cascade. This phenomenon was confirmed with suppressed Nrf2 phosphorylation and consequently diminished HO-1 expression in cells treated with a pharmacological inhibitor of ERK. Collectively, these results demonstrated that morin augments the cellular antioxidant defense capacity through the activation of Nrf2/HO‑1 signaling, which involves the activation of the ERK pathway, thereby protecting C2C12 myoblasts from H2O2-induced oxidative cytotoxicity.
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Affiliation(s)
- Moon Hee Lee
- Department of Biochemistry, Dongeui University College of Korean Medicine, Busan 614-052, Republic of Korea
| | - Min Ho Han
- Marine Biodiversity Institute of Korea, Seocheon 325-902, Republic of Korea
| | - Dae-Sung Lee
- Marine Biodiversity Institute of Korea, Seocheon 325-902, Republic of Korea
| | - Cheol Park
- Department of Molecular Biology, College of Natural Sciences and Human Ecology, Dongeui University, Busan 614-714, Republic of Korea
| | - Su-Hyun Hong
- Department of Biochemistry, Dongeui University College of Korean Medicine, Busan 614-052, Republic of Korea
| | - Gi-Young Kim
- Laboratory of Immunobiology, Department of Marine Life Sciences, Jeju National University, Jeju 690-756, Republic of Korea
| | - Sang Hoon Hong
- Department of Internal Medicine, Dongeui University College of Korean Medicine, Busan 614-052, Republic of Korea
| | - Kyoung Seob Song
- Department of Physiology, Kosin University College of Medicine, Busan 602-072, Republic of Korea
| | - Il-Whan Choi
- Department of Microbiology, College of Medicine, Inje University, Busan 608-737, Republic of Korea
| | - Hee-Jae Cha
- Department of Parasitology and Genetics, Kosin University College of Medicine, Busan 602-072, Republic of Korea
| | - Yung Hyun Choi
- Department of Biochemistry, Dongeui University College of Korean Medicine, Busan 614-052, Republic of Korea
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17
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Szczesny B, Marcatti M, Zatarain JR, Druzhyna N, Wiktorowicz JE, Nagy P, Hellmich MR, Szabo C. Inhibition of hydrogen sulfide biosynthesis sensitizes lung adenocarcinoma to chemotherapeutic drugs by inhibiting mitochondrial DNA repair and suppressing cellular bioenergetics. Sci Rep 2016; 6:36125. [PMID: 27808278 PMCID: PMC5093586 DOI: 10.1038/srep36125] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/11/2016] [Indexed: 12/11/2022] Open
Abstract
Therapeutic manipulation of the gasotransmitter hydrogen sulfide (H2S) has recently been proposed as a novel targeted anticancer approach. Here we show that human lung adenocarcinoma tissue expresses high levels of hydrogen sulfide (H2S) producing enzymes, namely, cystathionine beta-synthase (CBS), cystathionine gamma lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST), in comparison to adjacent lung tissue. In cultured lung adenocarcinoma but not in normal lung epithelial cells elevated H2S stimulates mitochondrial DNA repair through sulfhydration of EXOG, which, in turn, promotes mitochondrial DNA repair complex assembly, thereby enhancing mitochondrial DNA repair capacity. In addition, inhibition of H2S-producing enzymes suppresses critical bioenergetics parameters in lung adenocarcinoma cells. Together, inhibition of H2S-producing enzymes sensitize lung adenocarcinoma cells to chemotherapeutic agents via induction of mitochondrial dysfunction as shown in in vitro and in vivo models, suggesting a novel mechanism to overcome tumor chemoresistance.
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Affiliation(s)
- Bartosz Szczesny
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Michela Marcatti
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - John R Zatarain
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Nadiya Druzhyna
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - John E Wiktorowicz
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Péter Nagy
- Department of Molecular Immunology and Toxicology, National Institute of Oncology, Budapest 1122, Hungary
| | - Mark R Hellmich
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas 77555, USA
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18
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Chakraborty A, Tapryal N, Venkova T, Horikoshi N, Pandita RK, Sarker AH, Sarkar PS, Pandita TK, Hazra TK. Classical non-homologous end-joining pathway utilizes nascent RNA for error-free double-strand break repair of transcribed genes. Nat Commun 2016; 7:13049. [PMID: 27703167 PMCID: PMC5059474 DOI: 10.1038/ncomms13049] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/30/2016] [Indexed: 12/30/2022] Open
Abstract
DNA double-strand breaks (DSBs) leading to loss of nucleotides in the transcribed region can be lethal. Classical non-homologous end-joining (C-NHEJ) is the dominant pathway for DSB repair (DSBR) in adult mammalian cells. Here we report that during such DSBR, mammalian C-NHEJ proteins form a multiprotein complex with RNA polymerase II and preferentially associate with the transcribed genes after DSB induction. Depletion of C-NHEJ factors significantly abrogates DSBR in transcribed but not in non-transcribed genes. We hypothesized that nascent RNA can serve as a template for restoring the missing sequences, thus allowing error-free DSBR. We indeed found pre-mRNA in the C-NHEJ complex. Finally, when a DSB-containing plasmid with several nucleotides deleted within the E. coli lacZ gene was allowed time to repair in lacZ-expressing mammalian cells, a functional lacZ plasmid could be recovered from control but not C-NHEJ factor-depleted cells, providing important mechanistic insights into C-NHEJ-mediated error-free DSBR of the transcribed genome. Most adult mammalian cells prefer to repair double-strand DNA breaks though the classical nonhomologous end-joining pathway. Here the authors present evidence that a nascent RNA transcript can serve as a template to facilitate error-free repair.
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Affiliation(s)
- Anirban Chakraborty
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Nisha Tapryal
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Tatiana Venkova
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Nobuo Horikoshi
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, Texas 77030, USA
| | - Raj K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, Texas 77030, USA
| | - Altaf H Sarker
- Division of Life Sciences, Department of Cancer and DNA Damage Responses, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Partha S Sarkar
- Department of Neurology and Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Tej K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, Texas 77030, USA
| | - Tapas K Hazra
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
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19
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Lee YH, Kim JH, Song CH, Jang KJ, Kim CH, Kang JS, Choi YH, Yoon HM. Ethanol Extract of Ganoderma lucidum Augments Cellular Anti-oxidant Defense through Activation of Nrf2/HO-1. J Pharmacopuncture 2016; 19:59-69. [PMID: 27280051 PMCID: PMC4887753 DOI: 10.3831/kpi.2016.19.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Objectives: The mushroom Ganoderma lucidum has been widely used as a traditional herbal medicine for many years. Although several studies have focused on the anti-oxidative activity of this mushroom, the molecular mechanisms underlying its activity have not yet been clearly established. The present study investigated the cytoprotective effect of ethanol extract of Ganoderma lucidum (EGL) against oxidative stress (hydrogen peroxide, H2O2) and elucidated the underlying mechanisms in a C2C12 myoblast cell line. Methods: Oxidative stress markers were determined by using the comet assay to measure reactive oxygen species (ROS) generation and deoxyribonucleic acid (DNA) damage. Cell viability and Western blotting analyses were employed to evaluate the cellular response to EGL and H2O2 in C2C12 cells. Transfection with nuclear factor erythroid 2-related factor 2 (Nrf2)-specific small interfering ribonucleic acid (siRNA) was conducted to understand the relationship between Nrf2 expression and H2O2-induced growth inhibition. Results: The results showed that EGL effectively inhibited H2O2-induced growth and the generation of ROS. EGL markedly suppressed H2O2-induced comet-like DNA formation and phosphorylation of histone H2AX at serine 139 (p-γH2AX), a widely used marker of DNA damage, suggesting that EGL prevented H2O2-induced DNA damage. Furthermore, the EGL treatment effectively induced the expression of Nrf2, as well as heme oxygenase-1 (HO-1), with parallel phosphorylation and nuclear translocation of Nrf2 in the C2C12 myoblasts. However, zinc protoporphyrin IX, a HO-1 inhibitor, significantly abolished the protective effects of EGL against H2O2-induced accumulation of ROS and reduced cell growth. Notably, transient transfection with Nrf2-specific siRNA attenuated the cytoprotective effects and HO-1 induction by EGL, indicating that EGL induced the expression of HO-1 in an Nrf2-dependent manner. Conclusion: Collectively, these results demonstrate that EGL augments the cellular anti-oxidant defense capacity through activation of Nrf2/HO-1, thereby protecting C2C12 myoblasts from H2O2-induced oxidative cytotoxicity.
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Affiliation(s)
- Yoo-Hwan Lee
- Departments of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
| | - Jung-Hee Kim
- Departments of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
| | - Choon-Ho Song
- Departments of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
| | - Kyung-Jeon Jang
- Departments of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
| | - Cheol-Hong Kim
- Departments of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
| | - Ji-Sook Kang
- Anti-Aging Research Center, Dong-Eui University, Busan, Korea
| | - Yung-Hyun Choi
- Anti-Aging Research Center, Dong-Eui University, Busan, Korea; Department of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
| | - Hyun-Min Yoon
- Departments of Acupuncture and Moxibustion, Dong-Eui University College of Korean Medicine, Busan, Korea
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20
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AP39, a Mitochondria-Targeted Hydrogen Sulfide Donor, Supports Cellular Bioenergetics and Protects against Alzheimer's Disease by Preserving Mitochondrial Function in APP/PS1 Mice and Neurons. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:8360738. [PMID: 27057285 PMCID: PMC4753001 DOI: 10.1155/2016/8360738] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 01/11/2023]
Abstract
Increasing evidence suggests that mitochondrial functions are altered in AD and play an important role in AD pathogenesis. It has been established that H2S homeostasis is balanced in AD. The emerging mitochondrial roles of H2S include antioxidation, antiapoptosis, and the modulation of cellular bioenergetics. Here, using primary neurons from the well-characterized APP/PS1 transgenic mouse model, we studied the effects of AP39 (a newly synthesized mitochondrially targeted H2S donor) on mitochondrial function. AP39 increased intracellular H2S levels, mainly in mitochondrial regions. AP39 exerted dose-dependent effects on mitochondrial activity in APP/PS1 neurons, including increased cellular bioenergy metabolism and cell viability at low concentrations (25–100 nM) and decreased energy production and cell viability at a high concentration (250 nM). Furthermore, AP39 (100 nM) increased ATP levels, protected mitochondrial DNA, and decreased ROS generation. AP39 regulated mitochondrial dynamics, shifting from fission toward fusion. After 6 weeks, AP39 administration to APP/PS1 mice significantly ameliorated their spatial memory deficits in the Morris water maze and NORT and reduced Aβ deposition in their brains. Additionally, AP39 inhibited brain atrophy in APP/PS1 mice. Based on these results, AP39 was proposed as a promising drug candidate for AD treatment, and its anti-AD mechanism may involve protection against mitochondrial damage.
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21
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Van Houten B, Hunter SE, Meyer JN. Mitochondrial DNA damage induced autophagy, cell death, and disease. Front Biosci (Landmark Ed) 2016; 21:42-54. [PMID: 26709760 DOI: 10.2741/4375] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mammalian mitochondria contain multiple small genomes. While these organelles have efficient base excision removal of oxidative DNA lesions and alkylation damage, many DNA repair systems that work on nuclear DNA damage are not active in mitochondria. What is the fate of DNA damage in the mitochondria that cannot be repaired or that overwhelms the repair system? Some forms of mitochondrial DNA damage can apparently trigger mitochondrial DNA destruction, either via direct degradation or through specific forms of autophagy, such as mitophagy. However, accumulation of certain types of mitochondrial damage, in the absence of DNA ligase III (Lig3) or exonuclease G (EXOG), can directly trigger cell death. This review examines the cellular effects of persistent damage to mitochondrial genomes and discusses the very different cell fates that occur in response to different kinds of damage.
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Affiliation(s)
- Bennett Van Houten
- Department of Pharmacology Chemical Biology, University of Pittsburgh, 15213-1863,
| | - Senyene E Hunter
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC 27708-0328
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22
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Oláh G, Szczesny B, Brunyánszki A, López-García IA, Gerö D, Radák Z, Szabo C. Differentiation-Associated Downregulation of Poly(ADP-Ribose) Polymerase-1 Expression in Myoblasts Serves to Increase Their Resistance to Oxidative Stress. PLoS One 2015. [PMID: 26218895 PMCID: PMC4517814 DOI: 10.1371/journal.pone.0134227] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Poly(ADP-ribose) polymerase 1 (PARP-1), the major isoform of the poly (ADP-ribose) polymerase family, is a constitutive nuclear and mitochondrial protein with well-recognized roles in various essential cellular functions such as DNA repair, signal transduction, apoptosis, as well as in a variety of pathophysiological conditions including sepsis, diabetes and cancer. Activation of PARP-1 in response to oxidative stress catalyzes the covalent attachment of the poly (ADP-ribose) (PAR) groups on itself and other acceptor proteins, utilizing NAD+ as a substrate. Overactivation of PARP-1 depletes intracellular NAD+ influencing mitochondrial electron transport, cellular ATP generation and, if persistent, can result in necrotic cell death. Due to their high metabolic activity, skeletal muscle cells are particularly exposed to constant oxidative stress insults. In this study, we investigated the role of PARP-1 in a well-defined model of murine skeletal muscle differentiation (C2C12) and compare the responses to oxidative stress of undifferentiated myoblasts and differentiated myotubes. We observed a marked reduction of PARP-1 expression as myoblasts differentiated into myotubes. This alteration correlated with an increased resistance to oxidative stress of the myotubes, as measured by MTT and LDH assays. Mitochondrial function, assessed by measuring mitochondrial membrane potential, was preserved under oxidative stress in myotubes compared to myoblasts. Moreover, basal respiration, ATP synthesis, and the maximal respiratory capacity of mitochondria were higher in myotubes than in myoblasts. Inhibition of the catalytic activity of PARP-1 by PJ34 (a phenanthridinone PARP inhibitor) exerted greater protective effects in undifferentiated myoblasts than in differentiated myotubes. The above observations in C2C12 cells were also confirmed in a rat-derived skeletal muscle cell line (L6). Forced overexpression of PARP1 in C2C12 myotubes sensitized the cells to oxidant-induced injury. Taken together, our data indicate that the reduction of PARP-1 expression during the process of the skeletal muscle differentiation serves as a protective mechanism to maintain the cellular functions of skeletal muscle during oxidative stress.
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Affiliation(s)
- Gábor Oláh
- Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX, United States of America
| | - Bartosz Szczesny
- Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX, United States of America
- Shriners Hospital for Children, Galveston, TX, United States of America
| | - Attila Brunyánszki
- Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX, United States of America
| | - Isabel A. López-García
- Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX, United States of America
| | - Domokos Gerö
- Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX, United States of America
| | - Zsolt Radák
- Faculty of Physical Education and Sport Sciences, Semmelweis University, Alkotás Str. 44, Budapest, Hungary
| | - Csaba Szabo
- Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX, United States of America
- Shriners Hospital for Children, Galveston, TX, United States of America
- * E-mail:
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23
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Argilés JM, Busquets S, Stemmler B, López-Soriano FJ. Cachexia and sarcopenia: mechanisms and potential targets for intervention. Curr Opin Pharmacol 2015; 22:100-6. [PMID: 25974750 DOI: 10.1016/j.coph.2015.04.003] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/03/2015] [Accepted: 04/12/2015] [Indexed: 12/13/2022]
Abstract
Cachexia is a multi-organ syndrome associated with cancer and other chronic diseases, characterized by body weight loss, muscle and adipose tissue wasting and inflammation, being often associated with anorexia. Skeletal muscle tissue represents more than 40% of body weight and seems to be one of the main tissues involved in the wasting that occurs during cachexia. Sarcopenia is a degenerative loss of skeletal muscle mass, quality, and strength associated with healthy ageing. The molecular mechanisms behind cachexia and sarcopenia share some common trends. Muscle wasting is the result of a combination of an imbalance between synthetic and degradative protein pathways together with increased myocyte apoptosis and decreased regenerative capacity. Oxidative pathways are also altered in skeletal muscle during muscle wasting and this seems to be a consequence of mitochondrial abnormalities that include altered morphology and function, decreased ATP synthesis and uncoupling. The aim of the present review is to analyse common molecular pathways between cachexia and sarcopenia in order to put forward potential targets for intervention.
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Affiliation(s)
- Josep M Argilés
- Cancer Research Group, Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Institut de Biomedicina de la Universitat de Barcelona, Barcelona, Spain
| | - Silvia Busquets
- Cancer Research Group, Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Institut de Biomedicina de la Universitat de Barcelona, Barcelona, Spain.
| | | | - Francisco J López-Soriano
- Cancer Research Group, Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Institut de Biomedicina de la Universitat de Barcelona, Barcelona, Spain
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24
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Szczesny B, Brunyanszki A, Olah G, Mitra S, Szabo C. Opposing roles of mitochondrial and nuclear PARP1 in the regulation of mitochondrial and nuclear DNA integrity: implications for the regulation of mitochondrial function. Nucleic Acids Res 2014; 42:13161-73. [PMID: 25378300 PMCID: PMC4245951 DOI: 10.1093/nar/gku1089] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The positive role of PARP1 in regulation of various nuclear DNA transactions is well established. Although a mitochondrial localization of PARP1 has been suggested, its role in the maintenance of the mitochondrial DNA is currently unknown. Here we investigated the role of PARP1 in the repair of the mitochondrial DNA in the baseline and oxidative stress conditions. We used wild-type A549 cells or cells depleted of PARP1. Our data show that intra-mitochondrial PARP1 interacts with a key mitochondrial-specific DNA base excision repair (BER) enzymes, namely EXOG and DNA polymerase gamma (Polγ), which under oxidative stress become poly(ADP-ribose)lated (PARylated). Interaction between mitochondrial BER enzymes was significantly affected in the presence of PARP1. Moreover, the repair of the oxidative-induced damage to the mitochondrial DNA in PARP1-depleted cells was found to be more robust compared to control counterpart. In addition, mitochondrial biogenesis was enhanced in PARP1-depleted cells, including mitochondrial DNA copy number and mitochondrial membrane potential. This observation was further confirmed by analysis of lung tissue isolated from WT and PARP1 KO mice. In summary, we conclude that mitochondrial PARP1, in opposite to nuclear PARP1, exerts a negative effect on several mitochondrial-specific transactions including the repair of the mitochondrial DNA.
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Affiliation(s)
- Bartosz Szczesny
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Attila Brunyanszki
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Gabor Olah
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Sankar Mitra
- Radiation Oncology and Cancer Center, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA
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25
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Tigchelaar W, Yu H, de Jong AM, van Gilst WH, van der Harst P, Westenbrink BD, de Boer RA, Silljé HHW. Loss of mitochondrial exo/endonuclease EXOG affects mitochondrial respiration and induces ROS-mediated cardiomyocyte hypertrophy. Am J Physiol Cell Physiol 2014; 308:C155-63. [PMID: 25377088 DOI: 10.1152/ajpcell.00227.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Recently, a locus at the mitochondrial exo/endonuclease EXOG gene, which has been implicated in mitochondrial DNA repair, was associated with cardiac function. The function of EXOG in cardiomyocytes is still elusive. Here we investigated the role of EXOG in mitochondrial function and hypertrophy in cardiomyocytes. Depletion of EXOG in primary neonatal rat ventricular cardiomyocytes (NRVCs) induced a marked increase in cardiomyocyte hypertrophy. Depletion of EXOG, however, did not result in loss of mitochondrial DNA integrity. Although EXOG depletion did not induce fetal gene expression and common hypertrophy pathways were not activated, a clear increase in ribosomal S6 phosphorylation was observed, which readily explains increased protein synthesis. With the use of a Seahorse flux analyzer, it was shown that the mitochondrial oxidative consumption rate (OCR) was increased 2.4-fold in EXOG-depleted NRVCs. Moreover, ATP-linked OCR was 5.2-fold higher. This increase was not explained by mitochondrial biogenesis or alterations in mitochondrial membrane potential. Western blotting confirmed normal levels of the oxidative phosphorylation (OXPHOS) complexes. The increased OCR was accompanied by a 5.4-fold increase in mitochondrial ROS levels. These increased ROS levels could be normalized with specific mitochondrial ROS scavengers (MitoTEMPO, mnSOD). Remarkably, scavenging of excess ROS strongly attenuated the hypertrophic response. In conclusion, loss of EXOG affects normal mitochondrial function resulting in increased mitochondrial respiration, excess ROS production, and cardiomyocyte hypertrophy.
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Affiliation(s)
- Wardit Tigchelaar
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
| | - Hongjuan Yu
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and Department of Hematology, The First Clinical College of Harbin Medical University, Harbin, China
| | - Anne Margreet de Jong
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
| | - Wiek H van Gilst
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
| | - Pim van der Harst
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
| | - B Daan Westenbrink
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
| | - Rudolf A de Boer
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
| | - Herman H W Silljé
- University Medical Center Groningen, University of Groningen, Department of Cardiology, Groningen, The Netherlands; and
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26
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Alway SE, Myers MJ, Mohamed JS. Regulation of satellite cell function in sarcopenia. Front Aging Neurosci 2014; 6:246. [PMID: 25295003 PMCID: PMC4170136 DOI: 10.3389/fnagi.2014.00246] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/01/2014] [Indexed: 01/08/2023] Open
Abstract
The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell) function that is impacted by the environment (niche) of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse, or rehabilitation in sarcopenic muscles. Nutritional intervention provides one therapeutic strategy to improve the satellite cell niche and systemic factors, with the goal of improving satellite cell function in aging muscles. Although many elderly persons consume various nutraceuticals with the hope of improving health, most of these compounds have not been thoroughly tested, and the impacts that they might have on sarcopenia and satellite cell function are not clear. This review discusses data pertaining to the satellite cell responses and function in aging skeletal muscle, and the impact that three compounds: resveratrol, green tea catechins, and β-Hydroxy-β-methylbutyrate have on regulating satellite cell function and therefore contributing to reducing sarcopenia or improving muscle mass after disuse in aging. The data suggest that these nutraceutical compounds improve satellite cell function during rehabilitative loading in animal models of aging after disuse (i.e., muscle regeneration). While these compounds have not been rigorously tested in humans, the data from animal models of aging provide a strong basis for conducting additional focused work to determine if these or other nutraceuticals can offset the muscle losses, or improve regeneration in sarcopenic muscles of older humans via improving satellite cell function.
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Affiliation(s)
- Stephen E. Alway
- Laboratory of Muscle Biology and Sarcopenia, Department of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV, USA
- West Virginia Clinical and Translational Science Institute, Morgantown, WV, USA
- Center for Cardiovascular and Respiratory Sciences, Morgantown, WV, USA
| | - Matthew J. Myers
- Laboratory of Muscle Biology and Sarcopenia, Department of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV, USA
| | - Junaith S. Mohamed
- Laboratory of Muscle Biology and Sarcopenia, Department of Exercise Physiology, West Virginia University School of Medicine, Morgantown, WV, USA
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Brunyanszki A, Olah G, Coletta C, Szczesny B, Szabo C. Regulation of mitochondrial poly(ADP-Ribose) polymerase activation by the β-adrenoceptor/cAMP/protein kinase A axis during oxidative stress. Mol Pharmacol 2014; 86:450-62. [PMID: 25069723 DOI: 10.1124/mol.114.094318] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We investigated the regulation of mitochondrial poly(ADP-ribose) polymerase 1 (PARP1) by the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) system during oxidative stress in U937 monocytes. Oxidative stress induced an early (10 minutes) mitochondrial DNA damage, and concomitant activation of PARP1 in the mitochondria. These early events were followed by a progressive mitochondrial oxidant production and nuclear PARP1 activation (by 6 hours). These processes led to a functional impairment of mitochondria, culminating in cell death of mixed (necrotic/apoptotic) type. β-Adrenoceptor blockade with propranolol or inhibition of its downstream cAMP/PKA signaling attenuated, while β-adrenoceptor agonists and cAMP/PKA activators enhanced, the oxidant-mediated PARP1 activation. In the presence of cAMP, recombinant PKA directly phosphorylated recombinant PARP1 on serines 465 (in the automodification domain) and 782 and 785 (both in the catalytic domain). Inhibition of the β-adrenergic receptor/cAMP/PKA axis protected against the oxidant-mediated cell injury. Propranolol also suppressed PARP1 activation in peripheral blood leukocytes during bacterial lipopolysaccharide (LPS)-induced systemic inflammation in mice. We conclude that the activation of mitochondrial PARP1 is an early, active participant in oxidant-induced cell death, which is under the control of β-adrenoceptor/cAMP/PKA axis through the regulation of PARP1 activity by PARP1 phosphorylation.
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Affiliation(s)
- Attila Brunyanszki
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
| | - Gabor Olah
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
| | - Ciro Coletta
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
| | - Bartosz Szczesny
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
| | - Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas
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28
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Vitamin E in sarcopenia: current evidences on its role in prevention and treatment. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:914853. [PMID: 25097722 PMCID: PMC4109111 DOI: 10.1155/2014/914853] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/06/2014] [Indexed: 01/01/2023]
Abstract
Sarcopenia is a geriatric syndrome that is characterized by gradual loss of muscle mass and strength with increasing age. Although the underlying mechanism is still unknown, the contribution of increased oxidative stress in advanced age has been recognized as one of the risk factors of sarcopenia. Thus, eliminating reactive oxygen species (ROS) can be a strategy to combat sarcopenia. In this review, we discuss the potential role of vitamin E in the prevention and treatment of sarcopenia. Vitamin E is a lipid soluble vitamin, with potent antioxidant properties and current evidence suggesting a role in the modulation of signaling pathways. Previous studies have shown its possible beneficial effects on aging and age-related diseases. Although there are evidences suggesting an association between vitamin E and muscle health, they are still inconclusive compared to other more extensively studied chronic diseases such as neurodegenerative diseases and cardiovascular diseases. Therefore, we reviewed the role of vitamin E and its potential protective mechanisms on muscle health based on previous and current in vitro and in vivo studies.
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29
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Szczesny B, Módis K, Yanagi K, Coletta C, Le Trionnaire S, Perry A, Wood ME, Whiteman M, Szabo C. AP39, a novel mitochondria-targeted hydrogen sulfide donor, stimulates cellular bioenergetics, exerts cytoprotective effects and protects against the loss of mitochondrial DNA integrity in oxidatively stressed endothelial cells in vitro. Nitric Oxide 2014; 41:120-30. [PMID: 24755204 DOI: 10.1016/j.niox.2014.04.008] [Citation(s) in RCA: 202] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 04/08/2014] [Accepted: 04/14/2014] [Indexed: 12/12/2022]
Abstract
The purpose of the current study was to investigate the effect of the recently synthesized mitochondrially-targeted H2S donor, AP39 [(10-oxo-10-(4-(3-thioxo-3H-1,2-dithiol-5yl)phenoxy)decyl) triphenylphosphonium bromide], on bioenergetics, viability, and mitochondrial DNA integrity in bEnd.3 murine microvascular endothelial cells in vitro, under normal conditions, and during oxidative stress. Intracellular H2S was assessed by the fluorescent dye 7-azido-4-methylcoumarin. For the measurement of bioenergetic function, the XF24 Extracellular Flux Analyzer was used. Cell viability was estimated by the combination of the MTT and LDH methods. Oxidative protein modifications were measured by the Oxyblot method. Reactive oxygen species production was monitored by the MitoSOX method. Mitochondrial and nuclear DNA integrity were assayed by the Long Amplicon PCR method. Oxidative stress was induced by addition of glucose oxidase. Addition of AP39 (30-300 nM) to bEnd.3 cells increased intracellular H2S levels, with a preferential response in the mitochondrial regions. AP39 exerted a concentration-dependent effect on mitochondrial activity, which consisted of a stimulation of mitochondrial electron transport and cellular bioenergetic function at lower concentrations (30-100 nM) and an inhibitory effect at the higher concentration of 300 nM. Under oxidative stress conditions induced by glucose oxidase, an increase in oxidative protein modification and an enhancement in MitoSOX oxidation was noted, coupled with an inhibition of cellular bioenergetic function and a reduction in cell viability. AP39 pretreatment attenuated these responses. Glucose oxidase induced a preferential damage to the mitochondrial DNA; AP39 (100 nM) pretreatment protected against it. In conclusion, the current paper documents antioxidant and cytoprotective effects of AP39 under oxidative stress conditions, including a protection against oxidative mitochondrial DNA damage.
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Affiliation(s)
- Bartosz Szczesny
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Katalin Módis
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Kazunori Yanagi
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Ciro Coletta
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Sophie Le Trionnaire
- University of Exeter Medical School, St. Luke's Campus, Exeter, England, United Kingdom
| | - Alexis Perry
- Biosciences, College of Life and Environmental Science, University of Exeter, England, United Kingdom
| | - Mark E Wood
- Biosciences, College of Life and Environmental Science, University of Exeter, England, United Kingdom
| | - Matthew Whiteman
- University of Exeter Medical School, St. Luke's Campus, Exeter, England, United Kingdom.
| | - Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA.
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