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Kashiwagi S, Fujioka Y, Satoh AO, Yoshida A, Fujioka M, Nepal P, Tsuzuki A, Aoki O, Paudel S, Sasajima H, Ohba Y. Folding Latency of Fluorescent Proteins Affects the Mitochondrial Localization of Fusion Proteins. Cell Struct Funct 2019; 44:183-194. [PMID: 31735740 DOI: 10.1247/csf.19028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The discovery of fluorescent proteins (FPs) has revolutionized cell biology. The fusion of targeting sequences to FPs enables the investigation of cellular organelles and their dynamics; however, occasionally, such fluorescent fusion proteins (FFPs) exhibit behavior different from that of the native proteins. Here, we constructed a color pallet comprising different organelle markers and found that FFPs targeted to the mitochondria were mislocalized when fused to certain types of FPs. Such FPs included several variants of Aequorea victoria green FP (avGFP) and a monomeric variant of the red FP. Because the FFPs that are mislocalized include FPs with faster maturing or folding mutations, the increase in the maturation rate is likely to prevent their expected localization. Indeed, when we reintroduced amino acid substitutions so that the FP sequences were equivalent to that of wild-type avGFP, FFP localization to the mitochondria was significantly enhanced. Moreover, similar amino acid substitutions improved the localization of mitochondria-targeted pHluorin, which is a pH-sensitive variant of GFP, and its capability to monitor pH changes in the mitochondrial matrix. Our findings demonstrate the importance of selecting FPs that maximize FFP function.Key words: fluorescent protein, organelle, fusion protein, mitochondria.
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Affiliation(s)
- Sayaka Kashiwagi
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Yoichiro Fujioka
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Aya O Satoh
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Aiko Yoshida
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Mari Fujioka
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Prabha Nepal
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Atsushi Tsuzuki
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Ozora Aoki
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Sarad Paudel
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Hitoshi Sasajima
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
| | - Yusuke Ohba
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University
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2
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Towards the development of an enzyme replacement therapy for the metabolic disorder propionic acidemia. Mol Genet Metab Rep 2016; 8:51-60. [PMID: 27504265 PMCID: PMC4968140 DOI: 10.1016/j.ymgmr.2016.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/30/2016] [Accepted: 06/30/2016] [Indexed: 12/11/2022] Open
Abstract
Propionic acidemia (PA) is a life-threatening disease caused by the deficiency of a mitochondrial biotin-dependent enzyme known as propionyl coenzyme-A carboxylase (PCC). This enzyme is responsible for degrading the metabolic intermediate, propionyl coenzyme-A (PP-CoA), derived from multiple metabolic pathways. Currently, except for drastic surgical and dietary intervention that can only provide partial symptomatic relief, no other form of therapeutic option is available for this genetic disorder. Here, we examine a novel approach in protein delivery by specifically targeting and localizing our protein candidate of interest into the mitochondrial matrix of the cells. In order to test this concept of delivery, we have utilized cell penetrating peptides (CPPs) and mitochondria targeting sequences (MTS) to form specific fusion PCC protein, capable of translocating and localizing across cell membranes. In vitro delivery of our candidate fusion proteins, evaluated by confocal images and enzymatic activity assay, indicated effectiveness of this strategy. Therefore, it holds immense potential in creating a new paradigm in site-specific protein delivery and enzyme replacement therapeutic for PA.
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Key Words
- CPPs, cell penetrating peptides
- CoA, coenzyme-A
- ERT, enzyme replacement therapy
- Enzyme replacement therapy
- His-tag, six histidines tag
- LAD, lipoamine dehydrogenase
- MPP, mitochondrial processing peptidase
- MTS, mitochondria targeting sequences
- Mitochondrial targeting sequences
- PA, propionic acidemia
- PCC, propionyl coenzyme-A carboxylase
- PCCA, PCCα subunit
- PCCB, PCCβ subunit
- PP-CoA, propionyl coenzyme-A
- Propionic acidemia
- Propionyl coenzyme-A carboxylase
- Protein transduction domains
- UPLC-MS/MS, ultra performance liquid chromatography tandem mass spectrometry
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3
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Spadafora D, Kozhukhar N, Chouljenko VN, Kousoulas KG, Alexeyev MF. Methods for Efficient Elimination of Mitochondrial DNA from Cultured Cells. PLoS One 2016; 11:e0154684. [PMID: 27136098 PMCID: PMC4852919 DOI: 10.1371/journal.pone.0154684] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 04/18/2016] [Indexed: 12/17/2022] Open
Abstract
Here, we document that persistent mitochondria DNA (mtDNA) damage due to mitochondrial overexpression of the Y147A mutant uracil-N-glycosylase as well as mitochondrial overexpression of bacterial Exonuclease III or Herpes Simplex Virus protein UL12.5M185 can induce a complete loss of mtDNA (ρ0 phenotype) without compromising the viability of cells cultured in media supplemented with uridine and pyruvate. Furthermore, we use these observations to develop rapid, sequence-independent methods for the elimination of mtDNA, and demonstrate utility of these methods for generating ρ0 cells of human, mouse and rat origin. We also demonstrate that ρ0 cells generated by each of these three methods can serve as recipients of mtDNA in fusions with enucleated cells.
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Affiliation(s)
- Domenico Spadafora
- Department of Pharmacology, University of South Alabama, Mobile, Alabama, United States of America
| | - Nataliya Kozhukhar
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, United States of America
| | - Vladimir N. Chouljenko
- Division of Biotechnology & Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Konstantin G. Kousoulas
- Division of Biotechnology & Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Mikhail F. Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama, Mobile, Alabama, United States of America
- * E-mail:
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Karácsony Z, Gácser A, Vágvölgyi C, Scazzocchio C, Hamari Z. A dually located multi-HMG-box protein of Aspergillus nidulans has a crucial role in conidial and ascospore germination. Mol Microbiol 2014; 94:383-402. [PMID: 25156107 DOI: 10.1111/mmi.12772] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2014] [Indexed: 11/28/2022]
Abstract
Seven HMG-box proteins of Aspergillus nidulans have been identified in the genomic databases. Three of these have the characteristics of non-specific DNA-binding proteins. One of these, AN1267 (HmbB), comprises one canonical HMG-box in its C-terminus and upstream of the canonical box two structurally related boxes, to be called Shadow-HMG-boxes. This protein defines, together with the Podospora anserina mtHMG1, a clade of proteins present in the Pezizomycotina, with orthologues in some of the Taphrinomycotina. HmbB localizes primarily to the mitochondria but occasionally in nuclei. The deletion of the cognate gene results in a number of pleiotropic effects, including those on hyphal morphology, sensitivity to oxidative stress, absence of sterigmatocystin production and changes in the profile of conidial metabolites. The most striking phenotype of deletion strains is a dramatic decrease in conidial and ascospore viability. We show that this is most likely due to the protein being essential to maintain mitochondrial DNA in spores.
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Affiliation(s)
- Zoltán Karácsony
- University of Szeged Faculty of Sciences and Informatics, Department of Microbiology, H-6726, Szeged, Közép fasor 52, Hungary
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Shokolenko IN, Fayzulin RZ, Katyal S, McKinnon PJ, Wilson GL, Alexeyev MF. Mitochondrial DNA ligase is dispensable for the viability of cultured cells but essential for mtDNA maintenance. J Biol Chem 2013; 288:26594-605. [PMID: 23884459 DOI: 10.1074/jbc.m113.472977] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Multiple lines of evidence support the notion that DNA ligase III (LIG3), the only DNA ligase found in mitochondria, is essential for viability in both whole organisms and in cultured cells. Previous attempts to generate cells devoid of mitochondrial DNA ligase failed. Here, we report, for the first time, the derivation of viable LIG3-deficient mouse embryonic fibroblasts. These cells lack mtDNA and are auxotrophic for uridine and pyruvate, which may explain the apparent lethality of the Lig3 knock-out observed in cultured cells in previous studies. Cells with severely reduced expression of LIG3 maintain normal mtDNA copy number and respiration but show reduced viability in the face of alkylating and oxidative damage, increased mtDNA degradation in response to oxidative damage, and slow recovery from mtDNA depletion. Our findings clarify the cellular role of LIG3 and establish that the loss of viability in LIG3-deficient cells is conditional and secondary to the ρ(0) phenotype.
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6
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Shokolenko IN, Wilson GL, Alexeyev MF. Persistent damage induces mitochondrial DNA degradation. DNA Repair (Amst) 2013; 12:488-99. [PMID: 23721969 PMCID: PMC3683391 DOI: 10.1016/j.dnarep.2013.04.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/20/2013] [Accepted: 04/22/2013] [Indexed: 01/12/2023]
Abstract
Considerable progress has been made recently toward understanding the processes of mitochondrial DNA (mtDNA) damage and repair. However, a paucity of information still exists regarding the physiological effects of persistent mtDNA damage. This is due, in part, to experimental difficulties associated with targeting mtDNA for damage, while sparing nuclear DNA. Here, we characterize two systems designed for targeted mtDNA damage based on the inducible (Tet-ON) mitochondrial expression of the bacterial enzyme, exonuclease III, and the human enzyme, uracil-N-glyosylase containing the Y147A mutation. In both systems, damage was accompanied by degradation of mtDNA, which was detectable by 6h after induction of mutant uracil-N-glycosylase and by 12h after induction of exoIII. Unexpectedly, increases in the steady-state levels of single-strand lesions, which led to degradation, were small in absolute terms indicating that both abasic sites and single-strand gaps may be poorly tolerated in mtDNA. mtDNA degradation was accompanied by the loss of expression of mtDNA-encoded COX2. After withdrawal of the inducer, recovery from mtDNA depletion occurred faster in the system expressing exonuclease III, but in both systems reduced mtDNA levels persisted longer than 144h after doxycycline withdrawal. mtDNA degradation was followed by reduction and loss of respiration, decreased membrane potential, reduced cell viability, reduced intrinsic reactive oxygen species production, slowed proliferation, and changes in mitochondrial morphology (fragmentation of the mitochondrial network, rounding and "foaming" of the mitochondria). The mutagenic effects of abasic sites in mtDNA were low, which indicates that damaged mtDNA molecules may be degraded if not rapidly repaired. This study establishes, for the first time, that mtDNA degradation can be a direct and immediate consequence of persistent mtDNA damage and that increased ROS production is not an invariant consequence of mtDNA damage.
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Affiliation(s)
- Inna N. Shokolenko
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL (USA) 36688. Tel (251) 460-6772, Fax (251) 460-6771
| | - Glenn L. Wilson
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL (USA) 36688. Tel (251) 460-6765, Fax (251) 460-6771
| | - Mikhail F. Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL (USA) 36688
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Shokolenko IN, Alexeyev MF, LeDoux SP, Wilson GL. The approaches for manipulating mitochondrial proteome. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:451-461. [PMID: 20544885 PMCID: PMC3249350 DOI: 10.1002/em.20570] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Over the past decade a large volume of research data has accumulated which has established a fundamental role for mitochondria in normal cellular functioning, as well as in various pathologies. Mitochondria play a pivotal role in metabolism and energy production, and are one of the key players involved in programmed cell death. On the other hand, mitochondrial dysfunction is implicated, directly or indirectly in numerous pathological conditions including inherited mitochondrial disorders, diabetes, cardiovascular and neurodegenerative diseases, and a variety of malignancies. The ability to modulate mitochondrial function by altering the diverse protein component of this organelle may be of great value for developing future therapeutic interventions. This review will discuss approaches used to introduce proteins into mitochondria. One group of methods utilizes strategies aimed at expressing proteins from genes in the nucleus. These include overexpression of nuclear-encoded mitochondrial proteins, allotopic expression, which is the re-coding and relocation of mitochondrial genes to the nucleus for expression and subsequent delivery of their gene products to mitochondria, and xenotopic expression, which is the nuclear expression of genes coding electron transport chain components from distant species, for delivery of their products to mammalian mitochondria. Additionally, antigenomic and progenomic strategies which focus on expression of mitochondrially targeted nuclear proteins involved in the maintenance of mtDNA will be discussed. The second group of methods considered will focus on attempts to use purified proteins for mitochondrial delivery. Special consideration has been given to the complexities involved in targeting exogenous proteins to mitochondria.
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Pastukh V, Chen H, Wu S, Jong CJ, Alexeyev M, Schaffer SW. Effect of hypernatremia on injury caused by energy deficiency: role of T-type Ca2+ channel. Am J Physiol Cell Physiol 2010; 299:C289-97. [PMID: 20505041 DOI: 10.1152/ajpcell.00362.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypernatremia exerts multiple cellular effects, many of which could influence the outcome of an ischemic event. To further evaluate these effects of hypernatremia, isolated neonatal cardiomyocytes were chronically incubated with medium containing either normal (142 mM) or elevated sodium (167 mM) and then transferred to medium containing deoxyglucose and the electron transport chain inhibitor amobarbital. Chronic hypernatremia diminished the degree of calcium accumulation and reactive oxygen species generation during the period of metabolic inhibition. The improvement in calcium homeostasis was traced in part to the downregulation of the Ca(V)3.1 T-type calcium channel, as deficiency in the Ca(V)3.1 subtype using short hairpin RNA or treatment with an inhibitor of the Ca(V)3.1 variant of the T-type calcium channel (i.e., diphenylhydantoin) attenuated energy deficiency-mediated calcium accumulation and cell death. Although hyperosmotically stressed cells (exposed to 50 mM mannitol) had no effect on T-type calcium channel activity, they were also resistant to death during metabolic inhibition. Both hyperosmotic stress and hypernatremia activated Akt, suggesting that they initiate the phosphatidylinositol 3-kinase/Akt cytoprotective pathway, which protects the cell against calcium overload and oxidative stress. Thus hypernatremia appears to protect the cell against metabolic inhibition by promoting the downregulation of the T-type calcium channel and stimulating cytoprotective protein kinase pathways.
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Affiliation(s)
- Viktor Pastukh
- Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Alabama, USA
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9
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Alexeyev MF, Fayzulin R, Shokolenko IN, Pastukh V. A retro-lentiviral system for doxycycline-inducible gene expression and gene knockdown in cells with limited proliferative capacity. Mol Biol Rep 2009; 37:1987-91. [PMID: 19655272 DOI: 10.1007/s11033-009-9647-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 07/21/2009] [Indexed: 01/06/2023]
Abstract
Currently, there is no reliable system for regulated gene expression and regulated gene knockdown in cells with finite lifespan. In this manuscript, we describe a vector system, consisting of a retrovirus for the delivery of rtTA, and a lentivirus for the delivery of either a transgene or a miR-shRNA for the modification of primary cells. Primary rat pulmonary microvascular endothelial cells (PMVEC) modified by these vectors for the inducible expression of Gaussia luciferase or DsRed Express demonstrated greater than 100-fold induction of the transgene expression with doxycycline. The system works reliably in both sequential and simultaneous infection modes, with about 95% of the sells selected with two antibiotics being inducible in each mode. The lentiviral vector for gene knockdown allows for the direct cloning of shRNA oligos using alpha-complementation, and for the monitoring of induction of RNA interference with fluorescent reporter, mCherry. The gene knockdown vector was validated by knocking down beta-actin expression in PMVECs, with two of the four constructs showing 59 and 75% knockdown, respectively, compared to uninduced controls. The vectors described here were successfully used for the modification of various primary and established cell lines for regulated gene expression and regulated knockdown.
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Affiliation(s)
- Mikhail F Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, 307 University Blvd., Mobile, AL 36688, USA.
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Alexeyev MF, Venediktova N, Pastukh V, Shokolenko I, Bonilla G, Wilson GL. Selective elimination of mutant mitochondrial genomes as therapeutic strategy for the treatment of NARP and MILS syndromes. Gene Ther 2008; 15:516-23. [PMID: 18256697 PMCID: PMC10416612 DOI: 10.1038/gt.2008.11] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 11/19/2007] [Indexed: 12/26/2022]
Abstract
Mitochondrial diseases are not uncommon, and may result from mutations in both nuclear and mitochondrial DNA (mtDNA). At present, only palliative therapies are available for these disorders, and interest in the development of efficient treatment protocols is high. Here, we demonstrate that in cells heteroplasmic for the T8993G mutation, which is a cause for the NARP and MILS syndromes, infection with an adenovirus, which encodes the mitochondrially targeted R.XmaI restriction endonuclease, leads to selective destruction of mutant mtDNA. This destruction proceeds in a time- and dose-dependent manner and results in cells with significantly increased rates of oxygen consumption and ATP production. The delivery of R.XmaI to mitochondria is accompanied by improvement in the ability to utilize galactose as the sole carbon source, which is a surrogate indicator of the proficiency of oxidative phosphorylation. Concurrently, the rate of lactic acid production by these cells, which is a marker of mitochondrial dysfunction, decreases. We further demonstrate that levels of phosphorylated P53 and gammaH2ax proteins, markers of nuclear DNA damage, do not change in response to infection with recombinant adenovirus indicating the absence of nuclear DNA damage and the relative safety of the technique. Finally, some advantages and limitations of the proposed approach are discussed.
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Affiliation(s)
- M F Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL 36688, USA
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