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Sahayasheela VJ, Yu Z, Hidaka T, Pandian GN, Sugiyama H. Mitochondria and G-quadruplex evolution: an intertwined relationship. Trends Genet 2023; 39:15-30. [PMID: 36414480 PMCID: PMC9772288 DOI: 10.1016/j.tig.2022.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/27/2022] [Accepted: 10/27/2022] [Indexed: 11/21/2022]
Abstract
G-quadruplexes (G4s) are non-canonical structures formed in guanine (G)-rich sequences through stacked G tetrads by Hoogsteen hydrogen bonding. Several studies have demonstrated the existence of G4s in the genome of various organisms, including humans, and have proposed that G4s have a regulatory role in various cellular functions. However, little is known regarding the dissemination of G4s in mitochondria. In this review, we report the observation that the number of potential G4-forming sequences in the mitochondrial genome increases with the evolutionary complexity of different species, suggesting that G4s have a beneficial role in higher-order organisms. We also discuss the possible function of G4s in mitochondrial (mt)DNA and long noncoding (lnc)RNA and their role in various biological processes.
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Affiliation(s)
- Vinodh J Sahayasheela
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Zutao Yu
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Takuya Hidaka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Ganesh N Pandian
- Institute for Integrated Cell-Material Science (WPI-iCeMS), Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Hiroshi Sugiyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan; Institute for Integrated Cell-Material Science (WPI-iCeMS), Kyoto University, Sakyo, Kyoto 606-8501, Japan.
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2
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Jain M, Golzarroshan B, Lin CL, Agrawal S, Tang WH, Wu CJ, Yuan HS. Dimeric assembly of human Suv3 helicase promotes its RNA unwinding function in mitochondrial RNA degradosome for RNA decay. Protein Sci 2022; 31:e4312. [PMID: 35481630 PMCID: PMC9044407 DOI: 10.1002/pro.4312] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/21/2022] [Accepted: 04/01/2022] [Indexed: 11/12/2022]
Abstract
Human Suv3 is a unique homodimeric helicase that constitutes the major component of the mitochondrial degradosome to work cooperatively with exoribonuclease PNPase for efficient RNA decay. However, the molecular mechanism of how Suv3 is assembled into a homodimer to unwind RNA remains elusive. Here, we show that dimeric Suv3 preferentially binds to and unwinds DNA-DNA, DNA-RNA, and RNA-RNA duplexes with a long 3' overhang (≥10 nucleotides). The C-terminal tail (CTT)-truncated Suv3 (Suv3ΔC) becomes a monomeric protein that binds to and unwinds duplex substrates with ~six to sevenfold lower activities relative to dimeric Suv3. Only dimeric Suv3, but not monomeric Suv3ΔC, binds RNA independently of ATP or ADP, and is capable of interacting with PNPase, indicating that dimeric Suv3 assembly ensures its continuous association with RNA and PNPase during ATP hydrolysis cycles for efficient RNA degradation. We further determined the crystal structure of the apo-form of Suv3ΔC, and SAXS structures of dimeric Suv3 and PNPase-Suv3 complex, showing that dimeric Suv3 caps on the top of PNPase via interactions with S1 domains, and forms a dumbbell-shaped degradosome complex with PNPase. Overall, this study reveals that Suv3 is assembled into a dimeric helicase by its CTT for efficient and persistent RNA binding and unwinding to facilitate interactions with PNPase, promote RNA degradation, and maintain mitochondrial genome integrity and homeostasis.
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Affiliation(s)
- Monika Jain
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | - Chia-Liang Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Sashank Agrawal
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Wei-Hsuan Tang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan
| | - Chiu-Ju Wu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan
| | - Hanna S Yuan
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan
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3
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van Esveld SL, Rodenburg RJ, Al‐Murshedi F, Al‐Ajmi E, Al‐Zuhaibi S, Huynen MA, Spelbrink JN. Mitochondrial RNA processing defect caused by a SUPV3L1 mutation in two siblings with a novel neurodegenerative syndrome. J Inherit Metab Dis 2022; 45:292-307. [PMID: 35023579 PMCID: PMC9303385 DOI: 10.1002/jimd.12476] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 01/08/2022] [Accepted: 01/11/2022] [Indexed: 11/06/2022]
Abstract
SUPV3L1 encodes a helicase that is mainly localized in the mitochondria. It has been shown in vitro to possess both double-stranded RNA and DNA unwinding activity that is ATP-dependent. Here we report the first two patients for this gene who presented with a homozygous preliminary stop codon resulting in a C-terminal truncation of the SUPV3L1 protein. They presented with a characteristic phenotype of neurodegenerative nature with progressive spastic paraparesis, growth restriction, hypopigmentation, and predisposition to autoimmune disease. Ophthalmological examination showed severe photophobia with corneal erosions, optic atrophy, and pigmentary retinopathy, while neuroimaging showed atrophy of the optic chiasm and the pons with calcification of putamina, with intermittent and mild elevation of lactate. We show that the amino acids that are eliminated by the preliminary stop codon are highly conserved and are predicted to form an amphipathic helix. To investigate if the mutation causes mitochondrial dysfunction, we examined fibroblasts of the proband. We observed very low expression of the truncated protein, a reduction in the mature ND6 mRNA species as well as the accumulation of double-stranded RNA. Lentiviral complementation with the full-length SUPV3L1 cDNA partly restored the observed RNA phenotypes, supporting that the SUPV3L1 mutation in these patients is pathogenic and the cause of the disease.
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Affiliation(s)
- Selma L. van Esveld
- Radboud Center for Mitochondrial Medicine & Center for Molecular and Biomolecular InformaticsRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Richard J. Rodenburg
- Radboud Center for Mitochondrial Medicine, Department of Paediatrics, RadboudumcNijmegenThe Netherlands
| | - Fathiya Al‐Murshedi
- Genetic and Developmental Medicine ClinicSultan Qaboos University HospitalMuscatOman
| | - Eiman Al‐Ajmi
- Department of Radiology and Molecular ImagingSultan Qaboos University HospitalMuscatOman
| | - Sana Al‐Zuhaibi
- Department of OphthalmologySultan Qaboos University HospitalMuscatOman
| | - Martijn A. Huynen
- Radboud Center for Mitochondrial Medicine & Center for Molecular and Biomolecular InformaticsRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Johannes N. Spelbrink
- Radboud Center for Mitochondrial Medicine, Department of Paediatrics, RadboudumcNijmegenThe Netherlands
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4
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Petpiroon N, Rosena A, Pimtong W, Charoenlappanit S, Koobkokkruad T, Roytrakul S, Aueviriyavit S. Protective effects of Thai silk sericins and their related mechanisms on UVA-induced phototoxicity and melanogenesis: Investigation in primary melanocyte cells using a proteomic approach. Int J Biol Macromol 2021; 201:75-84. [PMID: 34968545 DOI: 10.1016/j.ijbiomac.2021.12.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 11/20/2021] [Accepted: 12/09/2021] [Indexed: 11/05/2022]
Abstract
UV radiation causes excess production of melanin as a result of hyperpigmentation and skin disorders. Silk sericin exhibited bioactivities to skin and inhibited UV-induced phototoxicity and melanogenesis in skin cells; however, the mechanism related to sericin against UV-induced melanogenesis has not been investigated. This study aimed to investigate the protective effects of Thai silk sericins against UVA-induced phototoxicity and melanogenesis and their related mechanisms. Thai silk sericins exhibited cytoprotective effects against UV-induced toxicity in human primary melanocytes by attenuation of cytotoxicity, intracellular ROS generation, and mitochondrial potential impairment. Pre- and post-treatment with sericin significantly inhibited melanin synthesis and tyrosinase activity against UVA exposure. In addition, sericin S2 could reduce the basal melanin content in zebrafish embryos. The proteomic analysis demonstrated that Thai silk sericins altered the protein expression in melanocytes especially proteins related to stress, inflammatory, cytokine stimulation, cell proliferation, and cell survival processes that contribute to cytoprotective effect and inhibitory effect on melanogenesis of sericin. Moreover, we demonstrated the novel mechanism of Thai silk sericins in inhibiting UVA-induced melanogenesis via increasing BMP4 expression in MAPK/ERK signaling pathway. These evidences support the potential use of Thai silk sericins in prevention of hyperpigmentation in skin disorders especially after UVA exposure.
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Affiliation(s)
- Nalinrat Petpiroon
- National Nanotechnology Center, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand
| | - Apiwan Rosena
- National Nanotechnology Center, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand
| | - Wittaya Pimtong
- National Nanotechnology Center, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand
| | - Sawanya Charoenlappanit
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand
| | - Thongchai Koobkokkruad
- National Nanotechnology Center, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand
| | - Sittiruk Roytrakul
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand
| | - Sasitorn Aueviriyavit
- National Nanotechnology Center, National Science and Technology Development Agency (NSTDA), Pathum Thani 12120, Thailand.
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5
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Interplay between Mitochondrial Metabolism and Cellular Redox State Dictates Cancer Cell Survival. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:1341604. [PMID: 34777681 PMCID: PMC8580634 DOI: 10.1155/2021/1341604] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 09/30/2021] [Accepted: 10/04/2021] [Indexed: 02/06/2023]
Abstract
Mitochondria are the main powerhouse of the cell, generating ATP through the tricarboxylic acid cycle (TCA) and oxidative phosphorylation (OXPHOS), which drives myriad cellular processes. In addition to their role in maintaining bioenergetic homeostasis, changes in mitochondrial metabolism, permeability, and morphology are critical in cell fate decisions and determination. Notably, mitochondrial respiration coupled with the passage of electrons through the electron transport chain (ETC) set up a potential source of reactive oxygen species (ROS). While low to moderate increase in intracellular ROS serves as secondary messenger, an overwhelming increase as a result of either increased production and/or deficient antioxidant defenses is detrimental to biomolecules, cells, and tissues. Since ROS and mitochondria both regulate cell fate, attention has been drawn to their involvement in the various processes of carcinogenesis. To that end, the link between a prooxidant milieu and cell survival and proliferation as well as a switch to mitochondrial OXPHOS associated with recalcitrant cancers provide testimony for the remarkable metabolic plasticity as an important hallmark of cancers. In this review, the regulation of cell redox status by mitochondrial metabolism and its implications for cancer cell fate will be discussed followed by the significance of mitochondria-targeted therapies for cancer.
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6
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Dumoulin B, Ufer C, Kuhn H, Sofi S. Expression Regulation, Protein Chemistry and Functional Biology of the Guanine-Rich Sequence Binding Factor 1 (GRSF1). J Mol Biol 2021; 433:166922. [PMID: 33713675 DOI: 10.1016/j.jmb.2021.166922] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 03/01/2021] [Accepted: 03/01/2021] [Indexed: 11/26/2022]
Abstract
In eukaryotic cells RNA-binding proteins have been implicated in virtually all post-transcriptional mechanisms of gene expression regulation. Based on the structural features of their RNA binding domains these proteins have been divided into several subfamilies. The presence of at least two RNA recognition motifs defines the group of heterogenous nuclear ribonucleoproteins H/F and one of its members is the guanine-rich sequence binding factor 1 (GRSF1). GRSF1 was first described 25 years ago and is widely distributed in eukaryotic cells. It is present in the nucleus, the cytoplasm and in mitochondria and has been implicated in a variety of physiological processes (embryogenesis, erythropoiesis, redox homeostasis, RNA metabolism) but also in the pathogenesis of various diseases. This review summarizes our current understanding on GRSF1 biology, critically discusses the literature reports and gives an outlook of future developments in the field.
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Affiliation(s)
- Bernhard Dumoulin
- Institute of Biochemistry, Charité - University Medicine Berlin, Corporate Member of Free University Berlin, Humboldt University Berlin and Berlin Institute of Health, Charitéplatz 1, D-10117 Berlin, Germany; III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Christoph Ufer
- Institute of Biochemistry, Charité - University Medicine Berlin, Corporate Member of Free University Berlin, Humboldt University Berlin and Berlin Institute of Health, Charitéplatz 1, D-10117 Berlin, Germany
| | - Hartmut Kuhn
- Institute of Biochemistry, Charité - University Medicine Berlin, Corporate Member of Free University Berlin, Humboldt University Berlin and Berlin Institute of Health, Charitéplatz 1, D-10117 Berlin, Germany
| | - Sajad Sofi
- University of York, Department of Biology, York YO10 5DD, United Kingdom
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7
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Peter B, Falkenberg M. TWINKLE and Other Human Mitochondrial DNA Helicases: Structure, Function and Disease. Genes (Basel) 2020; 11:genes11040408. [PMID: 32283748 PMCID: PMC7231222 DOI: 10.3390/genes11040408] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/30/2022] Open
Abstract
Mammalian mitochondria contain a circular genome (mtDNA) which encodes subunits of the oxidative phosphorylation machinery. The replication and maintenance of mtDNA is carried out by a set of nuclear-encoded factors—of which, helicases form an important group. The TWINKLE helicase is the main helicase in mitochondria and is the only helicase required for mtDNA replication. Mutations in TWINKLE cause a number of human disorders associated with mitochondrial dysfunction, neurodegeneration and premature ageing. In addition, a number of other helicases with a putative role in mitochondria have been identified. In this review, we discuss our current knowledge of TWINKLE structure and function and its role in diseases of mtDNA maintenance. We also briefly discuss other potential mitochondrial helicases and postulate on their role(s) in mitochondria.
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8
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Toompuu M, Tuomela T, Laine P, Paulin L, Dufour E, Jacobs HT. Polyadenylation and degradation of structurally abnormal mitochondrial tRNAs in human cells. Nucleic Acids Res 2019. [PMID: 29518244 PMCID: PMC6007314 DOI: 10.1093/nar/gky159] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
RNA 3' polyadenylation is known to serve diverse purposes in biology, in particular, regulating mRNA stability and translation. Here we determined that, upon exposure to high levels of the intercalating agent ethidium bromide (EtBr), greater than those required to suppress mitochondrial transcription, mitochondrial tRNAs in human cells became polyadenylated. Relaxation of the inducing stress led to rapid turnover of the polyadenylated tRNAs. The extent, kinetics and duration of tRNA polyadenylation were EtBr dose-dependent, with mitochondrial tRNAs differentially sensitive to the stress. RNA interference and inhibitor studies indicated that ongoing mitochondrial ATP synthesis, plus the mitochondrial poly(A) polymerase and SUV3 helicase were required for tRNA polyadenylation, while polynucleotide phosphorylase counteracted the process and was needed, along with SUV3, for degradation of the polyadenylated tRNAs. Doxycycline treatment inhibited both tRNA polyadenylation and turnover, suggesting a possible involvement of the mitoribosome, although other translational inhibitors had only minor effects. The dysfunctional tRNALeu(UUR) bearing the pathological A3243G mutation was constitutively polyadenylated at a low level, but this was markedly enhanced after doxycycline treatment. We propose that polyadenylation of structurally and functionally abnormal mitochondrial tRNAs entrains their PNPase/SUV3-mediated destruction, and that this pathway could play an important role in mitochondrial diseases associated with tRNA mutations.
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Affiliation(s)
- Marina Toompuu
- Faculty of Medicine and Life Sciences, BioMediTech Institute and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Tea Tuomela
- Faculty of Medicine and Life Sciences, BioMediTech Institute and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Pia Laine
- Institute of Biotechnology, FI-00014 University of Helsinki, Finland
| | - Lars Paulin
- Institute of Biotechnology, FI-00014 University of Helsinki, Finland
| | - Eric Dufour
- Faculty of Medicine and Life Sciences, BioMediTech Institute and Tampere University Hospital, FI-33014 University of Tampere, Finland
| | - Howard T Jacobs
- Faculty of Medicine and Life Sciences, BioMediTech Institute and Tampere University Hospital, FI-33014 University of Tampere, Finland.,Institute of Biotechnology, FI-00014 University of Helsinki, Finland
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9
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Human mitochondrial degradosome prevents harmful mitochondrial R loops and mitochondrial genome instability. Proc Natl Acad Sci U S A 2018; 115:11024-11029. [PMID: 30301808 DOI: 10.1073/pnas.1807258115] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
R loops are nucleic acid structures comprising an DNA-RNA hybrid and a displaced single-stranded DNA. These structures may occur transiently during transcription, playing essential biological functions. However, persistent R loops may become pathological as they are important drivers of genome instability and have been associated with human diseases. The mitochondrial degradosome is a functionally conserved complex from bacteria to human mitochondria. It is composed of the ATP-dependent RNA and DNA helicase SUV3 and the PNPase ribonuclease, playing a central role in mitochondrial RNA surveillance and degradation. Here we describe a new role for the mitochondrial degradosome in preventing the accumulation of pathological R loops in the mitochondrial DNA, in addition to preventing dsRNA accumulation. Our data indicate that, similar to the molecular mechanisms acting in the nucleus, RNA surveillance mechanisms in the mitochondria are crucial to maintain its genome integrity by counteracting pathological R-loop accumulation.
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10
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Dos Santos RF, Quendera AP, Boavida S, Seixas AF, Arraiano CM, Andrade JM. Major 3'-5' Exoribonucleases in the Metabolism of Coding and Non-coding RNA. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 159:101-155. [PMID: 30340785 DOI: 10.1016/bs.pmbts.2018.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
3'-5' exoribonucleases are key enzymes in the degradation of superfluous or aberrant RNAs and in the maturation of precursor RNAs into their functional forms. The major bacterial 3'-5' exoribonucleases responsible for both these activities are PNPase, RNase II and RNase R. These enzymes are of ancient nature with widespread distribution. In eukaryotes, PNPase and RNase II/RNase R enzymes can be found in the cytosol and in mitochondria and chloroplasts; RNase II/RNase R-like enzymes are also found in the nucleus. Humans express one PNPase (PNPT1) and three RNase II/RNase R family members (Dis3, Dis3L and Dis3L2). These enzymes take part in a multitude of RNA surveillance mechanisms that are critical for translation accuracy. Although active against a wide range of both coding and non-coding RNAs, the different 3'-5' exoribonucleases exhibit distinct substrate affinities. The latest studies on these RNA degradative enzymes have contributed to the identification of additional homologue proteins, the uncovering of novel RNA degradation pathways, and to a better comprehension of several disease-related processes and response to stress, amongst many other exciting findings. Here, we provide a comprehensive and up-to-date overview on the function, structure, regulation and substrate preference of the key 3'-5' exoribonucleases involved in RNA metabolism.
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Affiliation(s)
- Ricardo F Dos Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Ana P Quendera
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Sofia Boavida
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André F Seixas
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - José M Andrade
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
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11
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Shimada E, Ahsan FM, Nili M, Huang D, Atamdede S, TeSlaa T, Case D, Yu X, Gregory BD, Perrin BJ, Koehler CM, Teitell MA. PNPase knockout results in mtDNA loss and an altered metabolic gene expression program. PLoS One 2018; 13:e0200925. [PMID: 30024931 PMCID: PMC6053217 DOI: 10.1371/journal.pone.0200925] [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: 01/17/2018] [Accepted: 07/05/2018] [Indexed: 01/10/2023] Open
Abstract
Polynucleotide phosphorylase (PNPase) is an essential mitochondria-localized exoribonuclease implicated in multiple biological processes and human disorders. To reveal role(s) for PNPase in mitochondria, we established PNPase knockout (PKO) systems by first shifting culture conditions to enable cell growth with defective respiration. Interestingly, PKO established in mouse embryonic fibroblasts (MEFs) resulted in the loss of mitochondrial DNA (mtDNA). The transcriptional profile of PKO cells was similar to rho0 mtDNA deleted cells, with perturbations in cholesterol (FDR = 6.35 x 10-13), lipid (FDR = 3.21 x 10-11), and secondary alcohol (FDR = 1.04x10-12) metabolic pathway gene expression compared to wild type parental (TM6) MEFs. Transcriptome analysis indicates processes related to axonogenesis (FDR = 4.49 x 10-3), axon development (FDR = 4.74 x 10-3), and axonal guidance (FDR = 4.74 x 10-3) were overrepresented in PKO cells, consistent with previous studies detailing causative PNPase mutations in delayed myelination, hearing loss, encephalomyopathy, and chorioretinal defects in humans. Overrepresentation analysis revealed alterations in metabolic pathways in both PKO and rho0 cells. Therefore, we assessed the correlation of genes implicated in cell cycle progression and total metabolism and observed a strong positive correlation between PKO cells and rho0 MEFs compared to TM6 MEFs. We quantified the normalized biomass accumulation rate of PKO clones at 1.7% (SD ± 2.0%) and 2.4% (SD ± 1.6%) per hour, which was lower than TM6 cells at 3.3% (SD ± 3.5%) per hour. Furthermore, PKO in mouse inner ear hair cells caused progressive hearing loss that parallels human familial hearing loss previously linked to mutations in PNPase. Combined, our study reports that knockout of a mitochondrial nuclease results in mtDNA loss and suggests that mtDNA maintenance could provide a unifying connection for the large number of biological activities reported for PNPase.
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Affiliation(s)
- Eriko Shimada
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Fasih M. Ahsan
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Mahta Nili
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Dian Huang
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sean Atamdede
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Tara TeSlaa
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Dana Case
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
| | - Xiang Yu
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Brian D. Gregory
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Benjamin J. Perrin
- Department of Biology, Indiana University–Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Carla M. Koehler
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
- Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (CMK); (MAT)
| | - Michael A. Teitell
- Molecular Biology Institute Interdepartmental Program, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Bioengineering, University of California Los Angeles, Los Angeles, California, United States of America
- Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, California, United States of America
- Broad Center for Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Pediatrics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (CMK); (MAT)
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12
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Pietras Z, Wojcik MA, Borowski LS, Szewczyk M, Kulinski TM, Cysewski D, Stepien PP, Dziembowski A, Szczesny RJ. Dedicated surveillance mechanism controls G-quadruplex forming non-coding RNAs in human mitochondria. Nat Commun 2018; 9:2558. [PMID: 29967381 PMCID: PMC6028389 DOI: 10.1038/s41467-018-05007-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 06/08/2018] [Indexed: 12/13/2022] Open
Abstract
The GC skew in vertebrate mitochondrial genomes results in synthesis of RNAs that are prone to form G-quadruplexes (G4s). Such RNAs, although mostly non-coding, are transcribed at high rates and are degraded by an unknown mechanism. Here we describe a dedicated mechanism of degradation of G4-containing RNAs, which is based on cooperation between mitochondrial degradosome and quasi-RNA recognition motif (qRRM) protein GRSF1. This cooperation prevents accumulation of G4-containing transcripts in human mitochondria. In vitro reconstitution experiments show that GRSF1 promotes G4 melting that facilitates degradosome-mediated decay. Among degradosome and GRSF1 regulated transcripts we identified one that undergoes post-transcriptional modification. We show that GRSF1 proteins form a distinct qRRM group found only in vertebrates. The appearance of GRSF1 coincided with changes in the mitochondrial genome, which allows the emergence of G4-containing RNAs. We propose that GRSF1 appearance is an evolutionary adaptation enabling control of G4 RNA.
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Affiliation(s)
- Zbigniew Pietras
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland.,International Institute of Molecular and Cell Biology, Laboratory of Protein Structure, Ks. Trojdena 4, 02-109, Warsaw, Poland
| | - Magdalena A Wojcik
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland
| | - Lukasz S Borowski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland
| | - Maciej Szewczyk
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland
| | - Tomasz M Kulinski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland
| | - Dominik Cysewski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland
| | - Piotr P Stepien
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland
| | - Andrzej Dziembowski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland. .,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland.
| | - Roman J Szczesny
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Laboratory of RNA Biology and Functional Genomics, Pawinskiego 5A, 02-106, Warsaw, Poland. .,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland.
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13
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Abstract
Mitochondria play a crucial role in a variety of cellular processes ranging from energy metabolism, generation of reactive oxygen species (ROS) and Ca(2+) handling to stress responses, cell survival and death. Malfunction of the organelle may contribute to the pathogenesis of neuromuscular, cancer, premature aging and cardiovascular diseases (CVD), including myocardial ischemia, cardiomyopathy and heart failure (HF). Mitochondria contain their own genome organized into DNA-protein complexes, called "mitochondrial nucleoids," along with multiprotein machineries, which promote mitochondrial DNA (mtDNA) replication, transcription and repair. Although the mammalian organelle possesses almost all known nuclear DNA repair pathways, including base excision repair, mismatch repair and recombinational repair, the proximity of mtDNA to the main sites of ROS production and the lack of protective histones may result in increased susceptibility to various types of mtDNA damage. These include accumulation of mtDNA point mutations and/or deletions and decreased mtDNA copy number, which will impair mitochondrial function and finally, may lead to CVD including HF.
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Affiliation(s)
- José Marín-García
- The Molecular Cardiology and Neuromuscular Institute, 75 Raritan Avenue, Highland Park, NJ, 08904, USA.
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14
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Liu P, Huang J, Zheng Q, Xie L, Lu X, Jin J, Wang G. Mammalian mitochondrial RNAs are degraded in the mitochondrial intermembrane space by RNASET2. Protein Cell 2017; 8:735-749. [PMID: 28730546 PMCID: PMC5636749 DOI: 10.1007/s13238-017-0448-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/06/2017] [Indexed: 10/28/2022] Open
Abstract
Mammalian mitochondrial genome encodes a small set of tRNAs, rRNAs, and mRNAs. The RNA synthesis process has been well characterized. How the RNAs are degraded, however, is poorly understood. It was long assumed that the degradation happens in the matrix where transcription and translation machineries reside. Here we show that contrary to the assumption, mammalian mitochondrial RNA degradation occurs in the mitochondrial intermembrane space (IMS) and the IMS-localized RNASET2 is the enzyme that degrades the RNAs. This provides a new paradigm for understanding mitochondrial RNA metabolism and transport.
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Affiliation(s)
- Peipei Liu
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jinliang Huang
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Qian Zheng
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Leiming Xie
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xinping Lu
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jie Jin
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Geng Wang
- MOE Key laboratory of Bioinformatics, Cell Biology and Development Center, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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15
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Crouch JD, Brosh RM. Mechanistic and biological considerations of oxidatively damaged DNA for helicase-dependent pathways of nucleic acid metabolism. Free Radic Biol Med 2017; 107:245-257. [PMID: 27884703 PMCID: PMC5440220 DOI: 10.1016/j.freeradbiomed.2016.11.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/11/2016] [Accepted: 11/13/2016] [Indexed: 12/21/2022]
Abstract
Cells are under constant assault from reactive oxygen species that occur endogenously or arise from environmental agents. An important consequence of such stress is the generation of oxidatively damaged DNA, which is represented by a wide range of non-helix distorting and helix-distorting bulkier lesions that potentially affect a number of pathways including replication and transcription; consequently DNA damage tolerance and repair pathways are elicited to help cells cope with the lesions. The cellular consequences and metabolism of oxidatively damaged DNA can be quite complex with a number of DNA metabolic proteins and pathways involved. Many of the responses to oxidative stress involve a specialized class of enzymes known as helicases, the topic of this review. Helicases are molecular motors that convert the energy of nucleoside triphosphate hydrolysis to unwinding of structured polynucleic acids. Helicases by their very nature play fundamentally important roles in DNA metabolism and are implicated in processes that suppress chromosomal instability, genetic disease, cancer, and aging. We will discuss the roles of helicases in response to nuclear and mitochondrial oxidative stress and how this important class of enzymes help cells cope with oxidatively generated DNA damage through their functions in the replication stress response, DNA repair, and transcriptional regulation.
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Affiliation(s)
- Jack D Crouch
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA.
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16
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Shokolenko IN, Alexeyev MF. Mitochondrial transcription in mammalian cells. Front Biosci (Landmark Ed) 2017; 22:835-853. [PMID: 27814650 DOI: 10.2741/4520] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
As a consequence of recent discoveries of intimate involvement of mitochondria with key cellular processes, there has been a resurgence of interest in all aspects of mitochondrial biology, including the intricate mechanisms of mitochondrial DNA maintenance and expression. Despite four decades of research, there remains a lot to be learned about the processes that enable transcription of genetic information from mitochondrial DNA to RNA, as well as their regulation. These processes are vitally important, as evidenced by the lethality of inactivating the central components of mitochondrial transcription machinery. Here, we review the current understanding of mitochondrial transcription and its regulation in mammalian cells. We also discuss key theories in the field and highlight controversial subjects and future directions as we see them.
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Affiliation(s)
- Inna N Shokolenko
- University of South Alabama, Patt Capps Covey College of Allied Health Professions, Biomedical Sciences Department, 5721 USA Drive N, HAHN 4021, Mobile, AL 36688-0002, USA
| | - Mikhail F Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, 5851 USA Dr. North, MSB3074, Mobile, AL 36688, USA,
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17
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Uittenbogaard M, Chiaramello A. Novel subcellular localization of the DNA helicase Twinkle at the kinetochore complex during mitosis in neuronal-like progenitor cells. Histochem Cell Biol 2015; 145:275-86. [PMID: 26678504 DOI: 10.1007/s00418-015-1388-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2015] [Indexed: 11/28/2022]
Abstract
During mitosis, the kinetochore, a multi-protein structure located on the centromeric DNA, is responsible for proper segregation of the replicated genome. More specifically, the outer kinetochore complex component Ndc80/Hec1 plays a critical role in regulating microtubule attachment to the spindle for accurate sister chromatid segregation. In addition, DNA helicases play a key contribution for precise and complete disjunction of sister chromatids held together through double-stranded DNA catenations until anaphase. In this study, we focused our attention on the nuclear-encoded DNA helicase Twinkle, which functions as an essential helicase for replication of mitochondrial DNA. It regulates the copy number of the mitochondrial genome, while maintaining its integrity, two processes essential for mitochondrial biogenesis and bioenergetic functions. Although the majority of the Twinkle protein is imported into mitochondria, a small fraction remains cytosolic with an unknown function. In this study, we report a novel expression pattern of Twinkle during chromosomal segregation at distinct mitotic phases. By immunofluorescence microscopy, we found that Twinkle protein colocalizes with the outer kinetochore protein HEC1 as early as prophase until late anaphase in neuronal-like progenitor cells. Thus, our collective results have revealed an unexpected cell cycle-regulated expression pattern of the DNA helicase Twinkle, known for its role in mtDNA replication. Therefore, its recruitment to the kinetochore suggests an evolutionary conserved function for both mitochondrial and nuclear genomic inheritance.
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Affiliation(s)
- Martine Uittenbogaard
- Department of Anatomy and Regenerative Biology, George Washington University Medical Center, 2300 I Street N.W., Washington, DC, 20037, USA
| | - Anne Chiaramello
- Department of Anatomy and Regenerative Biology, George Washington University Medical Center, 2300 I Street N.W., Washington, DC, 20037, USA.
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18
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Clemente P, Pajak A, Laine I, Wibom R, Wedell A, Freyer C, Wredenberg A. SUV3 helicase is required for correct processing of mitochondrial transcripts. Nucleic Acids Res 2015; 43:7398-413. [PMID: 26152302 PMCID: PMC4551930 DOI: 10.1093/nar/gkv692] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/25/2015] [Indexed: 12/05/2022] Open
Abstract
Mitochondrial gene expression is largely regulated by post-transcriptional mechanisms that control the amount and translation of each mitochondrial mRNA. Despite its importance for mitochondrial function, the mechanisms and proteins involved in mRNA turnover are still not fully characterized. Studies in yeast and human cell lines have indicated that the mitochondrial helicase SUV3, together with the polynucleotide phosphorylase, PNPase, composes the mitochondrial degradosome. To further investigate the in vivo function of SUV3 we disrupted the homolog of SUV3 in Drosophila melanogaster (Dm). Loss of dmsuv3 led to the accumulation of mitochondrial mRNAs, without increasing rRNA levels, de novo transcription or decay intermediates. Furthermore, we observed a severe decrease in mitochondrial tRNAs accompanied by an accumulation of unprocessed precursor transcripts. These processing defects lead to reduced mitochondrial translation and a severe respiratory chain complex deficiency, resulting in a pupal lethal phenotype. In summary, our results propose that SUV3 is predominantly required for the processing of mitochondrial polycistronic transcripts in metazoan and that this function is independent of PNPase.
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Affiliation(s)
- Paula Clemente
- Division of Metabolic Diseases, Department of Laboratory Medicine; Karolinska Institutet, Stockholm 17177, Sweden
| | - Aleksandra Pajak
- Division of Metabolic Diseases, Department of Laboratory Medicine; Karolinska Institutet, Stockholm 17177, Sweden
| | - Isabelle Laine
- Division of Metabolic Diseases, Department of Laboratory Medicine; Karolinska Institutet, Stockholm 17177, Sweden
| | - Rolf Wibom
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm 17176, Sweden
| | - Anna Wedell
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm 17176, Sweden Department of Molecular Medicine and Surgery, Science for Life Laboratory, Karolinska Institutet, Stockholm 17176, Sweden
| | - Christoph Freyer
- Division of Metabolic Diseases, Department of Laboratory Medicine; Karolinska Institutet, Stockholm 17177, Sweden Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm 17176, Sweden
| | - Anna Wredenberg
- Division of Metabolic Diseases, Department of Laboratory Medicine; Karolinska Institutet, Stockholm 17177, Sweden Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm 17176, Sweden
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19
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Van Haute L, Pearce SF, Powell CA, D’Souza AR, Nicholls TJ, Minczuk M. Mitochondrial transcript maturation and its disorders. J Inherit Metab Dis 2015; 38:655-80. [PMID: 26016801 PMCID: PMC4493943 DOI: 10.1007/s10545-015-9859-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/27/2015] [Accepted: 04/29/2015] [Indexed: 11/03/2022]
Abstract
Mitochondrial respiratory chain deficiencies exhibit a wide spectrum of clinical presentations owing to defective mitochondrial energy production through oxidative phosphorylation. These defects can be caused by either mutations in the mitochondrial DNA (mtDNA) or mutations in nuclear genes coding for mitochondrially-targeted proteins. The underlying pathomechanisms can affect numerous pathways involved in mitochondrial biology including expression of mtDNA-encoded genes. Expression of the mitochondrial genes is extensively regulated at the post-transcriptional stage and entails nucleolytic cleavage of precursor RNAs, RNA nucleotide modifications, RNA polyadenylation, RNA quality and stability control. These processes ensure proper mitochondrial RNA (mtRNA) function, and are regulated by dedicated, nuclear-encoded enzymes. Recent growing evidence suggests that mutations in these nuclear genes, leading to incorrect maturation of RNAs, are a cause of human mitochondrial disease. Additionally, mutations in mtDNA-encoded genes may also affect RNA maturation and are frequently associated with human disease. We review the current knowledge on a subset of nuclear-encoded genes coding for proteins involved in mitochondrial RNA maturation, for which genetic variants impacting upon mitochondrial pathophysiology have been reported. Also, primary pathological mtDNA mutations with recognised effects upon RNA processing are described.
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Affiliation(s)
| | - Sarah F. Pearce
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
| | | | - Aaron R. D’Souza
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
| | - Thomas J. Nicholls
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
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20
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Ding L, Liu Y. Borrowing nuclear DNA helicases to protect mitochondrial DNA. Int J Mol Sci 2015; 16:10870-87. [PMID: 25984607 PMCID: PMC4463680 DOI: 10.3390/ijms160510870] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 05/09/2015] [Accepted: 05/11/2015] [Indexed: 01/20/2023] Open
Abstract
In normal cells, mitochondria are the primary organelles that generate energy, which is critical for cellular metabolism. Mitochondrial dysfunction, caused by mitochondrial DNA (mtDNA) mutations or an abnormal mtDNA copy number, is linked to a range of human diseases, including Alzheimer's disease, premature aging and cancer. mtDNA resides in the mitochondrial lumen, and its duplication requires the mtDNA replicative helicase, Twinkle. In addition to Twinkle, many DNA helicases, which are encoded by the nuclear genome and are crucial for nuclear genome integrity, are transported into the mitochondrion to also function in mtDNA replication and repair. To date, these helicases include RecQ-like helicase 4 (RECQ4), petite integration frequency 1 (PIF1), DNA replication helicase/nuclease 2 (DNA2) and suppressor of var1 3-like protein 1 (SUV3). Although the nuclear functions of some of these DNA helicases have been extensively studied, the regulation of their mitochondrial transport and the mechanisms by which they contribute to mtDNA synthesis and maintenance remain largely unknown. In this review, we attempt to summarize recent research progress on the role of mammalian DNA helicases in mitochondrial genome maintenance and the effects on mitochondria-associated diseases.
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Affiliation(s)
- Lin Ding
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
| | - Yilun Liu
- Department of Radiation Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
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21
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Audano M, Ferrari A, Fiorino E, Kuenzl M, Caruso D, Mitro N, Crestani M, De Fabiani E. Energizing Genetics and Epi-genetics: Role in the Regulation of Mitochondrial Function. Curr Genomics 2015; 15:436-56. [PMID: 25646072 PMCID: PMC4311388 DOI: 10.2174/138920291506150106151119] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/11/2014] [Accepted: 11/18/2014] [Indexed: 12/15/2022] Open
Abstract
Energy metabolism and mitochondrial function hold a core position in cellular homeostasis. Oxidative metabolism is regulated at multiple levels, ranging from gene transcription to allosteric modulation. To accomplish the fine tuning of these multiple regulatory circuits, the nuclear and mitochondrial compartments are tightly and reciprocally controlled. The fact that nuclear encoded factors, PPARγ coactivator 1α and mitochondrial transcription factor A, play pivotal roles in the regulation of oxidative metabolism and mitochondrial biogenesis is paradigmatic of this crosstalk. Here we provide an updated survey of the genetic and epigenetic mechanisms involved in the control of energy metabolism and mitochondrial function. Chromatin dynamics highly depends on post-translational modifications occurring at specific amino acids in histone proteins and other factors associated to nuclear DNA. In addition to the well characterized enzymes responsible for histone methylation/demethylation and acetylation/deacetylation, other factors have gone on the "metabolic stage". This is the case of the new class of α-ketoglutarate-regulated demethylases (Jumonji C domain containing demethylases) and of the NAD+-dependent deacetylases, also known as sirtuins. Moreover, unexpected features of the machineries involved in mitochondrial DNA (mtDNA) replication and transcription, mitochondrial RNA processing and maturation have recently emerged. Mutations or defects of any component of these machineries profoundly affect mitochondrial activity and oxidative metabolism. Finally, recent evidences support the importance of mtDNA packaging in replication and transcription. These observations, along with the discovery that non-classical CpG islands present in mtDNA undergo methylation, indicate that epigenetics also plays a role in the regulation of the mitochondrial genome function.
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Affiliation(s)
- Matteo Audano
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Alessandra Ferrari
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Erika Fiorino
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Martin Kuenzl
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Donatella Caruso
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Nico Mitro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Maurizio Crestani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
| | - Emma De Fabiani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Italy
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22
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Venø ST, Witt MB, Kulikowicz T, Bohr VA, Stevnsner T. Regulation of the human Suv3 helicase on DNA by inorganic cofactors. Biochimie 2014; 108:160-8. [PMID: 25446650 DOI: 10.1016/j.biochi.2014.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 11/05/2014] [Indexed: 11/19/2022]
Abstract
Mitochondria are essential organelles and consequently proper expression and maintenance of the mitochondrial genome are indispensable for proper cell function. The mitochondrial Suv3 (SUPV3L1) helicase is known to have a central role in mitochondrial RNA metabolism and to be essential for maintenance of mitochondrial DNA stability. Here we have performed biochemical investigations to determine the potential regulation of the human Suv3 (hSuv3) helicase function by inorganic cofactors. We find that hSuv3 helicase and ATPase activity in vitro is strictly dependent on the presence of specific divalent cations. Interestingly, we show that divalent cations and nucleotide concentration have a direct effect on helicase substrate stability. Also, hSuv3 helicase is able to utilize several different nucleotide cofactors including both NTPs and dNTPs. Intriguingly, the potency of the individual nucleotide as energy source for hSuv3 unwinding differed depending on the included divalent cation and nucleotide concentration. At low concentrations, all four NTPs could support helicase activity with varying effectiveness depending on the included divalent cation. However, at higher nucleotide concentrations, only ATP was able to elicit the helicase activity of hSuv3. Consequently, we speculate that the capacity of hSuv3 DNA unwinding activity might be sensitive to the local availability of specific inorganic cofactors.
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Affiliation(s)
- Susanne T Venø
- Danish Center of Molecular Gerontology and Danish Aging Research Center, University of Aarhus, Department of Molecular Biology and Genetics, Aarhus C DK-8000, Denmark
| | - Marie B Witt
- Danish Center of Molecular Gerontology and Danish Aging Research Center, University of Aarhus, Department of Molecular Biology and Genetics, Aarhus C DK-8000, Denmark
| | - Tomasz Kulikowicz
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Tinna Stevnsner
- Danish Center of Molecular Gerontology and Danish Aging Research Center, University of Aarhus, Department of Molecular Biology and Genetics, Aarhus C DK-8000, Denmark.
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23
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Umate P, Tuteja N, Tuteja R. Genome-wide comprehensive analysis of human helicases. Commun Integr Biol 2014. [DOI: 10.4161/cib.13844] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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24
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Wang DDH, Guo XE, Modrek AS, Chen CF, Chen PL, Lee WH. Helicase SUV3, polynucleotide phosphorylase, and mitochondrial polyadenylation polymerase form a transient complex to modulate mitochondrial mRNA polyadenylated tail lengths in response to energetic changes. J Biol Chem 2014; 289:16727-35. [PMID: 24770417 DOI: 10.1074/jbc.m113.536540] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian mitochondrial mRNA (mt-mRNA) transcripts are polyadenylated at the 3' end with different lengths. The SUV3·PNPase complex and mtPAP have been shown to degrade and polyadenylate mt mRNA, respectively. How these two opposite actions are coordinated to modulate mt-mRNA poly(A) lengths is of interest to pursue. Here, we demonstrated that a fraction of the SUV3·PNPase complex interacts with mitochondrial polyadenylation polymerase (mtPAP) under low mitochondrial matrix inorganic phosphate (Pi) conditions. In vitro binding experiments using purified proteins suggested that SUV3 binds to mtPAP through the N-terminal region around amino acids 100-104, distinctive from the C-terminal region around amino acids 510-514 of SUV3 for PNPase binding. mtPAP does not interact with PNPase directly, and SUV3 served as a bridge capable of simultaneously binding with mtPAP and PNPase. The complex consists of a SUV3 dimer, a mtPAP dimer, and a PNPase trimer, based on the molecular sizing experiments. Mechanistically, SUV3 provides a robust single strand RNA binding domain to enhance the polyadenylation activity of mtPAP. Furthermore, purified SUV3·PNPase·mtPAP complex is capable of lengthening or shortening the RNA poly(A) tail lengths in low or high Pi/ATP ratios, respectively. Consistently, the poly(A) tail lengths of mt-mRNA transcripts can be lengthened or shortened by altering the mitochondrial matrix Pi levels via selective inhibition of the electron transport chain or ATP synthase, respectively. Taken together, these results suggested that SUV3·PNPase·mtPAP form a transient complex to modulate mt-mRNA poly(A) tail lengths in response to cellular energy changes.
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Affiliation(s)
- Dennis Ding-Hwa Wang
- From the Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, California 92697 and
| | - Xuning Emily Guo
- From the Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, California 92697 and
| | - Aram Sandaldjian Modrek
- From the Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, California 92697 and
| | - Chi-Fen Chen
- From the Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, California 92697 and
| | - Phang-Lang Chen
- From the Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, California 92697 and
| | - Wen-Hwa Lee
- From the Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, California 92697 and the Graduate Institute of Clinical Medical Science, China Medical University, Taichung 40402, Taiwan
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25
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Wolf AR, Mootha VK. Functional genomic analysis of human mitochondrial RNA processing. Cell Rep 2014; 7:918-31. [PMID: 24746820 DOI: 10.1016/j.celrep.2014.03.035] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 02/14/2014] [Accepted: 03/11/2014] [Indexed: 11/16/2022] Open
Abstract
Both strands of human mtDNA are transcribed in continuous, multigenic units that are cleaved into the mature rRNAs, tRNAs, and mRNAs required for respiratory chain biogenesis. We sought to systematically identify nuclear-encoded proteins that contribute to processing of mtRNAs within the organelle. First, we devised and validated a multiplex MitoString assay that quantitates 27 mature and precursor mtDNA transcripts. Second, we applied MitoString profiling to evaluate the impact of silencing each of 107 mitochondrial-localized, predicted RNA-binding proteins. With the resulting data set, we rediscovered the roles of recently identified RNA-processing enzymes, detected unanticipated roles of known disease genes in RNA processing, and identified new regulatory factors. We demonstrate that one such factor, FASTKD4, modulates the half-lives of a subset of mt-mRNAs and associates with mtRNAs in vivo. MitoString profiling may be useful for diagnosing and deciphering the pathogenesis of mtDNA disorders.
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Affiliation(s)
- Ashley R Wolf
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute, Cambridge, MA 02141, USA
| | - Vamsi K Mootha
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute, Cambridge, MA 02141, USA.
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26
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Abstract
The Escherichia coli oligoribonuclease, ORN, has a 3′ to 5′ exonuclease activity specific for small oligomers that is essential for cell viability. The human homologue, REXO2, has hitherto been incompletely characterized, with only its in vitro ability to degrade small single-stranded RNA and DNA fragments documented. Here we show that the human enzyme has clear dual cellular localization being present both in cytosolic and mitochondrial fractions. Interestingly, the mitochondrial form localizes to both the intermembrane space and the matrix. Depletion of REXO2 by RNA interference causes a strong morphological phenotype in human cells, which show a disorganized network of punctate and granular mitochondria. Lack of REXO2 protein also causes a substantial decrease of mitochondrial nucleic acid content and impaired de novo mitochondrial protein synthesis. Our data constitute the first in vivo evidence for an oligoribonuclease activity in human mitochondria.
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Szczesny RJ, Wojcik MA, Borowski LS, Szewczyk MJ, Skrok MM, Golik P, Stepien PP. Yeast and human mitochondrial helicases. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:842-53. [PMID: 23454114 DOI: 10.1016/j.bbagrm.2013.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/13/2013] [Accepted: 02/14/2013] [Indexed: 11/19/2022]
Abstract
Mitochondria are semiautonomous organelles which contain their own genome. Both maintenance and expression of mitochondrial DNA require activity of RNA and DNA helicases. In Saccharomyces cerevisiae the nuclear genome encodes four DExH/D superfamily members (MSS116, SUV3, MRH4, IRC3) that act as helicases and/or RNA chaperones. Their activity is necessary for mitochondrial RNA splicing, degradation, translation and genome maintenance. In humans the ortholog of SUV3 (hSUV3, SUPV3L1) so far is the best described mitochondrial RNA helicase. The enzyme, together with the matrix-localized pool of PNPase (PNPT1), forms an RNA-degrading complex called the mitochondrial degradosome, which localizes to distinct structures (D-foci). Global regulation of mitochondrially encoded genes can be achieved by changing mitochondrial DNA copy number. This way the proteins involved in its replication, like the Twinkle helicase (c10orf2), can indirectly regulate gene expression. Here, we describe yeast and human mitochondrial helicases that are directly involved in mitochondrial RNA metabolism, and present other helicases that participate in mitochondrial DNA replication and maintenance. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
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Affiliation(s)
- Roman J Szczesny
- Institute of Genetics and Biotechnology, University of Warsaw, Warsaw, Poland
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28
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Borowski LS, Dziembowski A, Hejnowicz MS, Stepien PP, Szczesny RJ. Human mitochondrial RNA decay mediated by PNPase-hSuv3 complex takes place in distinct foci. Nucleic Acids Res 2012; 41:1223-40. [PMID: 23221631 PMCID: PMC3553951 DOI: 10.1093/nar/gks1130] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
RNA decay is usually mediated by protein complexes and can occur in specific foci such as P-bodies in the cytoplasm of eukaryotes. In human mitochondria nothing is known about the spatial organization of the RNA decay machinery, and the ribonuclease responsible for RNA degradation has not been identified. We demonstrate that silencing of human polynucleotide phosphorylase (PNPase) causes accumulation of RNA decay intermediates and increases the half-life of mitochondrial transcripts. A combination of fluorescence lifetime imaging microscopy with Förster resonance energy transfer and bimolecular fluorescence complementation (BiFC) experiments prove that PNPase and hSuv3 helicase (Suv3, hSuv3p and SUPV3L1) form the RNA-degrading complex in vivo in human mitochondria. This complex, referred to as the degradosome, is formed only in specific foci (named D-foci), which co-localize with mitochondrial RNA and nucleoids. Notably, interaction between PNPase and hSuv3 is essential for efficient mitochondrial RNA degradation. This provides indirect evidence that degradosome-dependent mitochondrial RNA decay takes place in foci.
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Affiliation(s)
- Lukasz S Borowski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, 02-106 Warsaw, Poland
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29
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Abstract
Contrary to conventional wisdom, functional mitochondria are essential for the cancer cell. Although mutations in mitochondrial genes are common in cancer cells, they do not inactivate mitochondrial energy metabolism but rather alter the mitochondrial bioenergetic and biosynthetic state. These states communicate with the nucleus through mitochondrial 'retrograde signalling' to modulate signal transduction pathways, transcriptional circuits and chromatin structure to meet the perceived mitochondrial and nuclear requirements of the cancer cell. Cancer cells then reprogramme adjacent stromal cells to optimize the cancer cell environment. These alterations activate out-of-context programmes that are important in development, stress response, wound healing and nutritional status.
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Affiliation(s)
- Douglas C Wallace
- Children's Hospital of Philadelphia, Center for Mitochondrial and Epigenomic Medicine, Philadelphia, Pennsylvania 19104, USA.
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30
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Conditional control of gene function by an invertible gene trap in zebrafish. Proc Natl Acad Sci U S A 2012; 109:15389-94. [PMID: 22908272 DOI: 10.1073/pnas.1206131109] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Conditional mutations are essential for determining the stage- and tissue-specific functions of genes. Here we achieve conditional mutagenesis in zebrafish using FT1, a gene-trap cassette that can be stably inverted by both Cre and Flp recombinases. We demonstrate that intronic insertions in the gene-trapping orientation severely disrupt the expression of the host gene, whereas intronic insertions in the neutral orientation do not significantly affect host gene expression. Cre- and Flp-mediated recombination switches the orientation of the gene-trap cassette, permitting conditional rescue in one orientation and conditional knockout in the other. To illustrate the utility of this system we analyzed the functional consequence of intronic FT1 insertion in supv3l1, a gene encoding a mitochondrial RNA helicase. Global supv311 mutants have impaired mitochondrial function, embryonic lethality, and agenesis of the liver. Conditional rescue of supv311 expression in hepatocytes specifically corrected the liver defects. To test whether the liver function of supv311 is required for viability we used Flp-mediated recombination in the germline to generate a neutral allele at the locus. Subsequently, tissue-specific expression of Cre conditionally inactivated the targeted locus. Hepatocyte-specific inactivation of supv311 caused liver degeneration, growth retardation, and juvenile lethality, a phenotype that was less severe than the global disruption of supv311. Thus, supv311 is required in multiple tissues for organismal viability. Our mutagenesis approach is very efficient and could be used to generate conditional alleles throughout the zebrafish genome. Furthermore, because FT1 is based on the promiscuous Tol2 transposon, it should be applicable to many organisms.
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Abstract
Mammalian mitochondria contain their own genome that encodes mRNAs for thirteen essential subunits of the complexes performing oxidative phosphorylation as well as the RNA components (two rRNAs and 22 tRNAs) needed for their translation in mitochondria. All RNA species are produced from single polycistronic precursor RNAs, yet the relative concentrations of various RNAs differ significantly. This underscores the essential role of post-transcriptional mechanisms that control the maturation, stability and translation of mitochondrial RNAs. The present review provides a detailed summary on the role of RNA maturation in the regulation of mitochondrial gene expression, focusing mainly on messenger RNA polyadenylation and stability control. Furthermore, the role of mitochondrial ribosomal RNA stability, processing and modifications in the biogenesis of the mitochondrial ribosome is discussed.
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Chen PL, Chen CF, Chen Y, Guo XE, Huang CK, Shew JY, Reddick RL, Wallace DC, Lee WH. Mitochondrial genome instability resulting from SUV3 haploinsufficiency leads to tumorigenesis and shortened lifespan. Oncogene 2012; 32:1193-201. [PMID: 22562243 PMCID: PMC3416964 DOI: 10.1038/onc.2012.120] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondrial dysfunction has been a hallmark of cancer. However, whether it has a causative role awaits to be elucidated. Here, using an animal model derived from inactivation of SUV3, a mitochondrial helicase, we demonstrated that mSuv3+/- mice harbored increased mitochondrial DNA (mtDNA) mutations and decreased mtDNA copy numbers, leading to tumor development in various sites and shortened lifespan. These phenotypes were transmitted maternally, indicating the etiological role of the mitochondria. Importantly, reduced SUV3 expression was observed in human breast tumor specimens compared with corresponding normal tissues in two independent cohorts. These results demonstrated for the first time that maintaining mtDNA integrity by SUV3 helicase is critical for cancer suppression.
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Affiliation(s)
- P-L Chen
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA, USA.
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The human Suv3 helicase interacts with replication protein A and flap endonuclease 1 in the nucleus. Biochem J 2012; 440:293-300. [PMID: 21846330 DOI: 10.1042/bj20100991] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The hSuv3 (human Suv3) helicase has been shown to be a major player in mitochondrial RNA surveillance and decay, but its physiological role might go beyond this functional niche. hSuv3 has been found to interact with BLM (Bloom's syndrome protein) and WRN (Werner's syndrome protein), members of the RecQ helicase family involved in multiple DNA metabolic processes, and in protection and stabilization of the genome. In the present study, we have addressed the possible role of hSuv3 in genome maintenance by examining its potential association with key interaction partners of the RecQ helicases. By analysis of hSuv3 co-IP (co-immunoprecipitation) complexes, we identify two new interaction partners of hSuv3: the RPA (replication protein A) and FEN1 (flap endonuclease 1). Utilizing an in vitro biochemical assay we find that low amounts of RPA inhibit helicase activity of hSuv3 on a forked substrate. Another single-strand-binding protein, mtSSB (mitochondrial single-strand-binding protein), fails to affect hSuv3 activity, indicating that the functional interaction is specific for hSuv3 and RPA. Further in vitro studies demonstrate that the flap endonuclease activity of FEN1 is stimulated by hSuv3 independently of flap length. hSuv3 is generally thought to be a mitochondrial helicase, but the physical and functional interactions between hSuv3 and known RecQ helicase-associated proteins strengthen the hypothesis that hSuv3 may play a significant role in nuclear DNA metabolism as well.
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Szczesny RJ, Borowski LS, Malecki M, Wojcik MA, Stepien PP, Golik P. RNA degradation in yeast and human mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:1027-34. [PMID: 22178375 DOI: 10.1016/j.bbagrm.2011.11.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 11/29/2011] [Accepted: 11/30/2011] [Indexed: 01/23/2023]
Abstract
Expression of mitochondrially encoded genes must be finely tuned according to the cell's requirements. Since yeast and human mitochondria have limited possibilities to regulate gene expression by altering the transcription initiation rate, posttranscriptional processes, including RNA degradation, are of great importance. In both organisms mitochondrial RNA degradation seems to be mostly depending on the RNA helicase Suv3. Yeast Suv3 functions in cooperation with Dss1 ribonuclease by forming a two-subunit complex called the mitochondrial degradosome. The human ortholog of Suv3 (hSuv3, hSuv3p, SUPV3L1) is also indispensable for mitochondrial RNA decay but its ribonucleolytic partner has so far escaped identification. In this review we summarize the current knowledge about RNA degradation in human and yeast mitochondria. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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Affiliation(s)
- Roman J Szczesny
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland.
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35
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Guo XE, Chen CF, Wang DDH, Modrek AS, Phan VH, Lee WH, Chen PL. Uncoupling the roles of the SUV3 helicase in maintenance of mitochondrial genome stability and RNA degradation. J Biol Chem 2011; 286:38783-38794. [PMID: 21911497 DOI: 10.1074/jbc.m111.257956] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Yeast SUV3 is a nuclear encoded mitochondrial RNA helicase that complexes with an exoribonuclease, DSS1, to function as an RNA degradosome. Inactivation of SUV3 leads to mitochondrial dysfunctions, such as respiratory deficiency; accumulation of aberrant RNA species, including excised group I introns; and loss of mitochondrial DNA (mtDNA). Although intron toxicity has long been speculated to be the major reason for the observed phenotypes, direct evidence to support or refute this theory is lacking. Moreover, it remains unknown whether SUV3 plays a direct role in mtDNA maintenance independently of its degradosome activity. In this paper, we address these questions by employing an inducible knockdown system in Saccharomyces cerevisiae with either normal or intronless mtDNA background. Expressing mutants defective in ATPase (K245A) or RNA binding activities (V272L or ΔCC, which carries an 8-amino acid deletion at the C-terminal conserved region) resulted in not only respiratory deficiencies but also loss of mtDNA under normal mtDNA background. Surprisingly, V272L, but not other mutants, can rescue the said deficiencies under intronless background. These results provide genetic evidence supporting the notion that the functional requirements of SUV3 for degradosome activity and maintenance of mtDNA stability are separable. Furthermore, V272L mutants and wild-type SUV3 associated with an active mtDNA replication origin and facilitated mtDNA replication, whereas K245A and ΔCC failed to support mtDNA replication. These results indicate a direct role of SUV3 in maintaining mitochondrial genome stability that is independent of intron turnover but requires the intact ATPase activity and the CC conserved region.
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Affiliation(s)
- Xuning Emily Guo
- Department of Biological Chemistry, University of California, Irvine, California 92697
| | - Chi-Fen Chen
- Department of Biological Chemistry, University of California, Irvine, California 92697
| | - Dennis Ding-Hwa Wang
- Department of Biological Chemistry, University of California, Irvine, California 92697
| | | | - Vy Hoai Phan
- Department of Biological Chemistry, University of California, Irvine, California 92697
| | - Wen-Hwa Lee
- Department of Biological Chemistry, University of California, Irvine, California 92697.
| | - Phang-Lang Chen
- Department of Biological Chemistry, University of California, Irvine, California 92697.
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36
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Zoppoli G, Douarre C, Dalla Rosa I, Liu H, Reinhold W, Pommier Y. Coordinated regulation of mitochondrial topoisomerase IB with mitochondrial nuclear encoded genes and MYC. Nucleic Acids Res 2011; 39:6620-32. [PMID: 21531700 PMCID: PMC3159436 DOI: 10.1093/nar/gkr208] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial DNA (mtDNA) is entirely dependent on nuclear genes for its transcription and replication. One of these genes is TOP1MT, which encodes the mitochondrial DNA topoisomerase IB, involved in mtDNA relaxation. To elucidate TOP1MT regulation, we performed genome-wide profiling across the 60-cell line panel (the NCI-60) of the National Cancer Institute Developmental Therapeutics Program. We show that TOP1MT mRNA expression varies widely across these cell lines with the highest levels in leukemia (HL-60, K-562) and melanoma (SK-MEL-28), intermediate levels in breast (MDA-MB-231), ovarian (OVCAR) and colon (HCT-116, HCT-15, KM-12), and lowest levels in renal (ACHN, A498), prostate (PC-3, DU-145) and central nervous system cell lines (SF-539, SF-268, SF-295). Genome-wide analyses show that TOP1MT expression is significantly correlated with the other mitochondrial nuclear-encoded genes including the mitochondrial nucleoid genes, and demonstrate an overall co-regulation of the mitochondrial nuclear-encoded genes. We also find very high correlation between the expression of TOP1MT and the proto-oncogene MYC (c-myc). TOP1MT contains E-boxes (c-myc binding sites) and TOP1MT transcription follows MYC up- and down-regulation by MYC promoter activation and siRNA against MYC. Our finding implicates MYC as a novel regulator of TOP1MT and confirms its role as a master regulator of MNEGs and mitochondrial nucleoids.
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Affiliation(s)
- Gabriele Zoppoli
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20890, USA.
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37
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Umate P, Tuteja N, Tuteja R. Genome-wide comprehensive analysis of human helicases. Commun Integr Biol 2011; 4:118-37. [PMID: 21509200 PMCID: PMC3073292 DOI: 10.4161/cib.4.1.13844] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 10/03/2010] [Indexed: 12/20/2022] Open
Abstract
Helicases are motor proteins that catalyze the unwinding of duplex nucleic acids in an ATP-dependent manner. They are involved in almost all the nucleic acid transactions. In the present study, we report a comprehensive analysis of helicase gene family in human and its comparison with homologs in model organisms. The human genome encodes for 95 non-redundant helicase proteins, of which 64 are RNA helicases and 31 are DNA helicases. 57 RNA helicases are validated based on annotations and occurrence of conserved helicase signature motifs. These include 14 DExH and 37 DExD subfamily members, six other members such as U5.snRNP, ATR-X, Suv3, FANCJ, and two of superkiller viralicidic activity 2-like helicases. 31 DNA helicases are also identified, which include RecQ, MCM and RuvB-like helicases. Finding a set of helicases in human and almost similar sequences in model organisms suggests that the "core" members of helicase gene family are highly conserved throughout evolution. The present study gives an overview of members of RNA and DNA helicases encoded by the human genome along with their conserved motifs, phylogeny and homologs in model organisms. The study on comparing these homologs will spread light on the organization and complexity of helicase gene family in model organisms. The comprehensive analysis of human helicases presented in this study will further provide an invaluable resource for elaborate biological research on these helicases.
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Affiliation(s)
- Pavan Umate
- International Center for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi, India
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38
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Human polynucleotide phosphorylase (hPNPase(old-35)): an evolutionary conserved gene with an expanding repertoire of RNA degradation functions. Oncogene 2010; 30:1733-43. [PMID: 21151174 PMCID: PMC4955827 DOI: 10.1038/onc.2010.572] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Human polynucleotide phosphorylase (hPNPase(old-35)) is an evolutionary conserved RNA-processing enzyme with expanding roles in regulating cellular physiology. hPNPase(old-35) was cloned using an innovative 'overlapping pathway screening' strategy designed to identify genes coordinately regulated during the processes of cellular differentiation and senescence. Although hPNPase(old-35) structurally and biochemically resembles PNPase of other species, overexpression and inhibition studies reveal that hPNPase(old-35) has evolved to serve more specialized and diversified functions in humans. Targeting specific mRNA or non-coding small microRNA, hPNPase(old-35) modulates gene expression that in turn has a pivotal role in regulating normal physiological and pathological processes. In these contexts, targeted overexpression of hPNPase(old-35) represents a novel strategy to selectively downregulate RNA expression and consequently intervene in a variety of pathophysiological conditions.
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39
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Mitochondrial helicases and mitochondrial genome maintenance. Mech Ageing Dev 2010; 131:503-10. [PMID: 20576512 DOI: 10.1016/j.mad.2010.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/26/2010] [Accepted: 04/28/2010] [Indexed: 12/28/2022]
Abstract
Helicases are essential enzymes that utilize the energy of nucleotide hydrolysis to drive unwinding of nucleic acid duplexes. Helicases play roles in all aspects of DNA metabolism including DNA repair, DNA replication and transcription. The subcellular locations and functions of several helicases have been studied in detail; however, the roles of specific helicases in mitochondrial biology remain poorly characterized. This review presents important recent advances in identifying and characterizing mitochondrial helicases, some of which also operate in the nucleus.
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40
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Mitochondrial translation and beyond: processes implicated in combined oxidative phosphorylation deficiencies. J Biomed Biotechnol 2010; 2010:737385. [PMID: 20396601 PMCID: PMC2854570 DOI: 10.1155/2010/737385] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 01/29/2010] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial disorders are a heterogeneous group of often multisystemic and early fatal diseases, which are amongst the most common inherited human diseases. These disorders are caused by defects in the oxidative phosphorylation (OXPHOS) system, which comprises five multisubunit enzyme complexes encoded by both the nuclear and the mitochondrial genomes. Due to the multitude of proteins and intricacy of the processes required for a properly functioning OXPHOS system, identifying the genetic defect that underlies an OXPHOS deficiency is not an easy task, especially in the case of combined OXPHOS defects. In the present communication we give an extensive overview of the proteins and processes (in)directly involved in mitochondrial translation and the biogenesis of the OXPHOS system and their roles in combined OXPHOS deficiencies. This knowledge is important for further research into the genetic causes, with the ultimate goal to effectively prevent and cure these complex and often devastating disorders.
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41
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Borowski LS, Szczesny RJ, Brzezniak LK, Stepien PP. RNA turnover in human mitochondria: more questions than answers? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1066-70. [PMID: 20117077 DOI: 10.1016/j.bbabio.2010.01.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 01/19/2010] [Accepted: 01/25/2010] [Indexed: 01/16/2023]
Abstract
Protein complexes responsible for RNA degradation play important role in three key aspects of RNA metabolism: they control stability of physiologically functional transcripts, remove the unnecessary RNA processing intermediates and destroy aberrantly formed RNAs. In mitochondria the post-transcriptional events seem to play a major role in regulation of gene expression, therefore RNA turnover is of particular importance. Despite many years of research, the details of this process are still a challenge. This review summarizes emerging landscape of interplay between the Suv3p helicase (SUPV3L1, Suv3), poly(A) polymerase and polynucleotide phosphorylase in controlling RNA degradation in human mitochondria.
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Affiliation(s)
- Lukasz S Borowski
- Institute of Genetics and Biotechnology, Faculty of Biology, Warsaw University, Pawinskiego 5a, 02-106 Warsaw, Poland
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42
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Lipinski KA, Kaniak-Golik A, Golik P. Maintenance and expression of the S. cerevisiae mitochondrial genome--from genetics to evolution and systems biology. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1086-98. [PMID: 20056105 DOI: 10.1016/j.bbabio.2009.12.019] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 12/18/2009] [Accepted: 12/24/2009] [Indexed: 10/20/2022]
Abstract
As a legacy of their endosymbiotic eubacterial origin, mitochondria possess a residual genome, encoding only a few proteins and dependent on a variety of factors encoded by the nuclear genome for its maintenance and expression. As a facultative anaerobe with well understood genetics and molecular biology, Saccharomyces cerevisiae is the model system of choice for studying nucleo-mitochondrial genetic interactions. Maintenance of the mitochondrial genome is controlled by a set of nuclear-coded factors forming intricately interconnected circuits responsible for replication, recombination, repair and transmission to buds. Expression of the yeast mitochondrial genome is regulated mostly at the post-transcriptional level, and involves many general and gene-specific factors regulating splicing, RNA processing and stability and translation. A very interesting aspect of the yeast mitochondrial system is the relationship between genome maintenance and gene expression. Deletions of genes involved in many different aspects of mitochondrial gene expression, notably translation, result in an irreversible loss of functional mtDNA. The mitochondrial genetic system viewed from the systems biology perspective is therefore very fragile and lacks robustness compared to the remaining systems of the cell. This lack of robustness could be a legacy of the reductive evolution of the mitochondrial genome, but explanations involving selective advantages of increased evolvability have also been postulated.
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Affiliation(s)
- Kamil A Lipinski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5A, 02-106, Warsaw, Poland
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43
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Abstract
Helicases are essential enzymes involved in all aspects of nucleic acid metabolism including DNA replication, repair, recombination, transcription, ribosome biogenesis and RNA processing, translation, and decay. They occur in vivo as part of molecular complexes that include the components required for each specific step of nucleic acid metabolism. The role of the helicases is to utilize the energy derived from nucleoside triphosphate hydrolysis to translocate along nucleic acid strands, unwind/separate the helical structure of double-stranded nucleic acid, and, in some cases, disrupt protein-nucleic acid interactions. Because of their essential function, helicases are ubiquitous and evolutionary conserved proteins. This chapter briefly highlights helicase structure and activities and provides examples of the helicases involved in nucleic acid metabolism.
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Affiliation(s)
- Mohamed Abdelhaleem
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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44
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Widespread expression of the Supv3L1 mitochondrial RNA helicase in the mouse. Transgenic Res 2009; 19:691-701. [PMID: 19937380 DOI: 10.1007/s11248-009-9346-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Accepted: 11/10/2009] [Indexed: 10/20/2022]
Abstract
Supv3L1 is an evolutionarily conserved helicase that plays a critical role in the mitochondrial RNA surveillance and degradation machinery. Conditional ablation of Supv3L1 in adult mice leads to premature aging phenotypes including loss of muscle mass and adipose tissue and severe skin abnormalities. To get insights into the spatial and temporal expression of Supv3L1 in the mouse, we generated knock-in and transgenic strains in which an EGFP reporter was placed under control of the Supv3L1 native promoter. During development, expression of Supv3L1 begins at the blastocyst stage, becomes widespread and strong in all fetal tissues and cell types, and continues during postnatal growth. In mature animals reporter expression is only slightly diminished in most tissues and continues to be highly expressed in the brain, peripheral sensory organs, and testis. Together, these data confirm that Supv3L1 is an important developmentally regulated gene, which continues to be expressed in all mature tissues, particularly the rapidly proliferating cells of testes, but also in the brain and sensory organs. The transgenic mice and cell lines derived from them constitute a valuable tool for the examination of the spatial and temporal aspects of Supv3L1 promoter activity, and should facilitate future screens for small molecules that regulate Supv3L1 expression.
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45
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Szczesny RJ, Borowski LS, Brzezniak LK, Dmochowska A, Gewartowski K, Bartnik E, Stepien PP. Human mitochondrial RNA turnover caught in flagranti: involvement of hSuv3p helicase in RNA surveillance. Nucleic Acids Res 2009; 38:279-98. [PMID: 19864255 PMCID: PMC2800237 DOI: 10.1093/nar/gkp903] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The mechanism of human mitochondrial RNA turnover and surveillance is still a matter of debate. We have obtained a cellular model for studying the role of hSuv3p helicase in human mitochondria. Expression of a dominant-negative mutant of the hSUV3 gene which encodes a protein with no ATPase or helicase activity results in perturbations of mtRNA metabolism and enables to study the processing and degradation intermediates which otherwise are difficult to detect because of their short half-lives. The hSuv3p activity was found to be necessary in the regulation of stability of mature, properly formed mRNAs and for removal of the noncoding processing intermediates transcribed from both H and L-strands, including mirror RNAs which represent antisense RNAs transcribed from the opposite DNA strand. Lack of hSuv3p function also resulted in accumulation of aberrant RNA species, molecules with extended poly(A) tails and degradation intermediates truncated predominantly at their 3′-ends. Moreover, we present data indicating that hSuv3p co-purifies with PNPase; this may suggest participation of both proteins in mtRNA metabolism.
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Affiliation(s)
- Roman J Szczesny
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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Baughman JM, Nilsson R, Gohil VM, Arlow DH, Gauhar Z, Mootha VK. A computational screen for regulators of oxidative phosphorylation implicates SLIRP in mitochondrial RNA homeostasis. PLoS Genet 2009; 5:e1000590. [PMID: 19680543 PMCID: PMC2721412 DOI: 10.1371/journal.pgen.1000590] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 07/09/2009] [Indexed: 11/18/2022] Open
Abstract
The human oxidative phosphorylation (OxPhos) system consists of approximately 90 proteins encoded by nuclear and mitochondrial genomes and serves as the primary cellular pathway for ATP biosynthesis. While the core protein machinery for OxPhos is well characterized, many of its assembly, maturation, and regulatory factors remain unknown. We exploited the tight transcriptional control of the genes encoding the core OxPhos machinery to identify novel regulators. We developed a computational procedure, which we call expression screening, which integrates information from thousands of microarray data sets in a principled manner to identify genes that are consistently co-expressed with a target pathway across biological contexts. We applied expression screening to predict dozens of novel regulators of OxPhos. For two candidate genes, CHCHD2 and SLIRP, we show that silencing with RNAi results in destabilization of OxPhos complexes and a marked loss of OxPhos enzymatic activity. Moreover, we show that SLIRP plays an essential role in maintaining mitochondrial-localized mRNA transcripts that encode OxPhos protein subunits. Our findings provide a catalogue of potential novel OxPhos regulators that advance our understanding of the coordination between nuclear and mitochondrial genomes for the regulation of cellular energy metabolism. Respiratory chain disorders represent the largest class of inborn errors in metabolism affecting 1 in every 5,000 individuals. Biochemically, these disorders are characterized by a breakdown in the cellular process called oxidative phosphorylation (OxPhos), which is responsible for generating most of the cell's energy in the form of ATP. Sadly, for approximately 50% of patients diagnosed, we do not know the molecular cause behind these disorders. One possible reason for our limited diagnostic capability is that these patients harbor a mutation in a gene that is not known to act in the OxPhos pathway. We therefore designed a computational strategy called expression screening that integrates publicly available genome-wide gene expression data to predict new genes that may play a role in OxPhos biology. We identified several uncharacterized genes that were strongly predicted by our procedure to function in the OxPhos pathway and experimentally validated two genes, SLIRP and CHCHD2, as being essential for OxPhos function. These genes, as well as others predicted by expression screening to regulate OxPhos, represent a valuable resource for identifying the molecular underpinnings of respiratory chain disorders.
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Affiliation(s)
- Joshua M. Baughman
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Roland Nilsson
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Vishal M. Gohil
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Daniel H. Arlow
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Zareen Gauhar
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Vamsi K. Mootha
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Mattiacio JL, Read LK. Evidence for a degradosome-like complex in the mitochondria of Trypanosoma brucei. FEBS Lett 2009; 583:2333-8. [PMID: 19540236 DOI: 10.1016/j.febslet.2009.06.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 06/11/2009] [Indexed: 12/21/2022]
Abstract
Mitochondrial RNA turnover in yeast involves the degradosome, composed of DSS-1 exoribonuclease and SUV3 RNA helicase. Here, we describe a degradosome-like complex, containing SUV3 and DSS-1 homologues, in the early branching protozoan, Trypanosoma brucei. TbSUV3 is mitochondrially localized and co-sediments with TbDSS-1 on glycerol gradients. Co-immunoprecipitation demonstrates that TbSUV3 and TbDSS-1 associate in a stable complex, which differs from the yeast degradosome in that it is not stably associated with mitochondrial ribosomes. This is the first report of a mitochondrial degradosome-like complex outside of yeast. Our data indicate an early evolutionary origin for the mitochondrial SUV3/DSS-1 containing complex.
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Affiliation(s)
- Jonelle L Mattiacio
- Depatment of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, SUNY Buffalo School of Medicine, Buffalo, NY 14214, USA
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Wang DDH, Shu Z, Lieser SA, Chen PL, Lee WH. Human mitochondrial SUV3 and polynucleotide phosphorylase form a 330-kDa heteropentamer to cooperatively degrade double-stranded RNA with a 3'-to-5' directionality. J Biol Chem 2009; 284:20812-21. [PMID: 19509288 DOI: 10.1074/jbc.m109.009605] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Efficient turnover of unnecessary and misfolded RNAs is critical for maintaining the integrity and function of the mitochondria. The mitochondrial RNA degradosome of budding yeast (mtEXO) has been recently studied and characterized; yet no RNA degradation machinery has been identified in the mammalian mitochondria. In this communication, we demonstrated that purified human SUV3 (suppressor of Var1 3) dimer and polynucleotide phosphorylase (PNPase) trimer form a 330-kDa heteropentamer that is capable of efficiently degrading double-stranded RNA (dsRNA) substrates in the presence of ATP, a task the individual components cannot perform separately. The configuration of this complex is similar to that of the core complex of the E. coli RNA degradosome lacking RNase E but very different from that of the yeast mtEXO. The hSUV3-hPNPase complex prefers substrates containing a 3' overhang and degrades the RNA in a 3'-to-5' directionality. Deleting a short stretch of amino acids (positions 510-514) compromises the ability of hSUV3 to form a stable complex with hPNPase to degrade dsRNA substrates but does not affect its helicase activity. Furthermore, two additional hSUV3 mutants with abolished helicase activity because of disrupted ATPase or RNA binding activities were able to bind hPNPase. However, the resulting complexes failed to degrade dsRNA, suggesting that an intact helicase activity is essential for the complex to serve as an effective RNA degradosome. Taken together, these results strongly suggest that the complex of hSUV3-hPNPase is an integral entity for efficient degradation of structured RNA and may be the long sought RNA-degrading complex in the mammalian mitochondria.
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Affiliation(s)
- Dennis Ding-Hwa Wang
- Department of Biological Chemistry, University of California, Irvine, California 92697, USA.
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Paul E, Cronan R, Weston PJ, Boekelheide K, Sedivy JM, Lee SY, Wiest DL, Resnick MB, Klysik JE. Disruption of Supv3L1 damages the skin and causes sarcopenia, loss of fat, and death. Mamm Genome 2009; 20:92-108. [PMID: 19145458 DOI: 10.1007/s00335-008-9168-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Accepted: 12/03/2008] [Indexed: 01/26/2023]
Abstract
Supv3L1 is a conserved and ubiquitously expressed helicase found in numerous tissues and cell types of many species. In human cells, SUPV3L1 was shown to suppress apoptotic death and sister chromatid exchange, and impair mitochondrial RNA metabolism and protein synthesis. In vitro experiments revealed binding of SUPV3L1 to BLM and WRN proteins, suggesting a role in genome maintenance processes. Disruption of the Supv3L1 gene in the mouse has been reported to be embryonic lethal at early developmental stages. We generated a conditional mouse in which the phenotypes associated with the removal of exon 14 can be tested in a variety of tissues. Disruption mediated by a Mx1 promoter-driven Cre displayed a postnatal growth delay, reduced lifespan, loss of adipose tissue and muscle mass, and severe skin abnormalities manifesting as ichthyosis, thickening of the epidermis, and atrophy of the dermis and subcutaneous tissue. Using a tamoxifen-activatable Esr1/Cre driver, Supv3L1 disruption resulted in growth retardation and aging phenotypes, including loss of adipose tissue and muscle mass, kyphosis, cachexia, and premature death. Many of the abnormalities seen in the Mx1-Cre mice, such as hyperkeratosis characterized by profound scaling of feet and tail, could also be detected in tamoxifen-inducible Cre mice. Conditional ablation of Supv3L1 in keratinocytes confirmed atrophic changes in the skin and ichthyosis-like changes. Together, these data indicate that Supv3L1 is important for the maintenance of the skin barrier. In addition, loss of Supv3L1 function leads to accelerated aging-like phenotypes.
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Affiliation(s)
- Erin Paul
- Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship St., Providence, RI 02903, USA
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