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Manini A, Abati E, Comi GP, Corti S, Ronchi D. Mitochondrial DNA homeostasis impairment and dopaminergic dysfunction: A trembling balance. Ageing Res Rev 2022; 76:101578. [PMID: 35114397 DOI: 10.1016/j.arr.2022.101578] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/26/2021] [Accepted: 01/28/2022] [Indexed: 02/07/2023]
Abstract
Maintenance of mitochondrial DNA (mtDNA) homeostasis includes a variety of processes, such as mtDNA replication, repair, and nucleotides synthesis, aimed at preserving the structural and functional integrity of mtDNA molecules. Mutations in several nuclear genes (i.e., POLG, POLG2, TWNK, OPA1, DGUOK, MPV17, TYMP) impair mtDNA maintenance, leading to clinical syndromes characterized by mtDNA depletion and/or deletions in affected tissues. In the past decades, studies have demonstrated a progressive accumulation of multiple mtDNA deletions in dopaminergic neurons of the substantia nigra in elderly population and, to a greater extent, in Parkinson's disease patients. Moreover, parkinsonism has been frequently described as a prominent clinical feature in mtDNA instability syndromes. Among Parkinson's disease-related genes with a significant role in mitochondrial biology, PARK2 and LRRK2 specifically take part in mtDNA maintenance. Moreover, a variety of murine models (i.e., "Mutator", "MitoPark", "PD-mitoPstI", "Deletor", "Twinkle-dup" and "TwinkPark") provided in vivo evidence that mtDNA stability is required to preserve nigrostriatal integrity. Here, we review and discuss the clinical, genetic, and pathological background underlining the link between impaired mtDNA homeostasis and dopaminergic degeneration.
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Nuclear genes involved in mitochondrial diseases caused by instability of mitochondrial DNA. J Appl Genet 2018; 59:43-57. [PMID: 29344903 PMCID: PMC5799321 DOI: 10.1007/s13353-017-0424-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 12/20/2017] [Indexed: 02/07/2023]
Abstract
Mitochondrial diseases are defined by a respiratory chain dysfunction and in most of the cases manifest as multisystem disorders with predominant expression in muscles and nerves and may be caused by mutations in mitochondrial (mtDNA) or nuclear (nDNA) genomes. Most of the proteins involved in respiratory chain function are nuclear encoded, although 13 subunits of respiratory chain complexes (together with 2 rRNAs and 22 tRNAs necessary for their translation) encoded by mtDNA are essential for cell function. nDNA encodes not only respiratory chain subunits but also all the proteins responsible for mtDNA maintenance, especially those involved in replication, as well as other proteins necessary for the transcription and copy number control of this multicopy genome. Mutations in these genes can cause secondary instability of the mitochondrial genome in the form of depletion (decreased number of mtDNA molecules in the cell), vast multiple deletions or accumulation of point mutations which in turn leads to mitochondrial diseases inherited in a Mendelian fashion. The list of genes involved in mitochondrial DNA maintenance is long, and still incomplete.
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Wang L. Mitochondrial purine and pyrimidine metabolism and beyond. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 35:578-594. [PMID: 27906631 DOI: 10.1080/15257770.2015.1125001] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Carefully balanced deoxynucleoside triphosphate (dNTP) pools are essential for both nuclear and mitochondrial genome replication and repair. Two synthetic pathways operate in cells to produce dNTPs, e.g., the de novo and the salvage pathways. The key regulatory enzymes for de novo synthesis are ribonucleotide reductase (RNR) and thymidylate synthase (TS), and this process is considered to be cytosolic. The salvage pathway operates both in the cytosol (TK1 and dCK) and the mitochondria (TK2 and dGK). Mitochondrial dNTP pools are separated from the cytosolic ones owing to the double membrane structure of the mitochondria, and are formed by the salvage enzymes TK2 and dGK together with NMPKs and NDPK in postmitotic tissues, while in proliferating cells the mitochondrial dNTPs are mainly imported from the cytosol produced by the cytosolic pathways. Imbalanced mitochondrial dNTP pools lead to mtDNA depletion and/or deletions resulting in serious mitochondrial diseases. The mtDNA depletion syndrome is caused by deficiencies not only in enzymes in dNTP synthesis (TK2, dGK, p53R2, and TP) and mtDNA replication (mtDNA polymerase and twinkle helicase), but also in enzymes in other metabolic pathways such as SUCLA2 and SUCLG1, ABAT and MPV17. Basic questions are why defects in these enzymes affect dNTP synthesis and how important is mitochondrial nucleotide synthesis in the whole cell/organism perspective? This review will focus on recent studies on purine and pyrimidine metabolism, which have revealed several important links that connect mitochondrial nucleotide metabolism with amino acids, glucose, and fatty acid metabolism.
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Affiliation(s)
- Liya Wang
- a Department of Anatomy, Physiology and Biochemistry , Swedish University of Agricultural Sciences , Uppsala , Sweden
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Garcia-Esparcia P, López-González I, Grau-Rivera O, García-Garrido MF, Konetti A, Llorens F, Zafar S, Carmona M, Del Rio JA, Zerr I, Gelpi E, Ferrer I. Dementia with Lewy Bodies: Molecular Pathology in the Frontal Cortex in Typical and Rapidly Progressive Forms. Front Neurol 2017; 8:89. [PMID: 28348546 PMCID: PMC5346561 DOI: 10.3389/fneur.2017.00089] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 02/24/2017] [Indexed: 11/29/2022] Open
Abstract
Objectives The goal of this study was to assess mitochondrial function, energy, and purine metabolism, protein synthesis machinery from the nucleolus to the ribosome, inflammation, and expression of newly identified ectopic olfactory receptors (ORs) and taste receptors (TASRs) in the frontal cortex of typical cases of dementia with Lewy bodies (DLB) and cases with rapid clinical course (rpDLB: 2 years or less) compared with middle-aged non-affected individuals, in order to learn about the biochemical abnormalities underlying Lewy body pathology. Methods Real-time quantitative PCR, mitochondrial enzymatic assays, and analysis of β-amyloid, tau, and synuclein species were used. Results The main alterations in DLB and rpDLB, which are more marked in the rapidly progressive forms, include (i) deregulated expression of several mRNAs and proteins of mitochondrial subunits, and reduced activity of complexes I, II, III, and IV of the mitochondrial respiratory chain; (ii) reduced expression of selected molecules involved in energy metabolism and increased expression of enzymes involved in purine metabolism; (iii) abnormal expression of nucleolar proteins, rRNA18S, genes encoding ribosomal proteins, and initiation factors of the transcription at the ribosome; (iv) discrete inflammation; and (v) marked deregulation of brain ORs and TASRs, respectively. Severe mitochondrial dysfunction involving activity of four complexes, minimal inflammatory responses, and dramatic altered expression of ORs and TASRs discriminate DLB from Alzheimer’s disease. Altered solubility and aggregation of α-synuclein, increased β-amyloid bound to membranes, and absence of soluble tau oligomers are common in DLB and rpDLB. Low levels of soluble β-amyloid are found in DLB. However, increased soluble β-amyloid 1–40 and β-amyloid 1–42, and increased TNFα mRNA and protein expression, distinguish rpDLB. Conclusion Molecular alterations in frontal cortex in DLB involve key biochemical pathways such as mitochondria and energy metabolism, protein synthesis, purine metabolism, among others and are accompanied by discrete innate inflammatory response.
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Affiliation(s)
- Paula Garcia-Esparcia
- Institute of Neuropathology, Service of Pathologic Anatomy, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain; CIBERNED, Network Centre for Biomedical Research of Neurodegenerative Diseases, Institute Carlos III, Madrid, Spain
| | - Irene López-González
- Institute of Neuropathology, Service of Pathologic Anatomy, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain; CIBERNED, Network Centre for Biomedical Research of Neurodegenerative Diseases, Institute Carlos III, Madrid, Spain
| | - Oriol Grau-Rivera
- Neurological Tissue Bank of the Biobanc-Hospital Clínic-Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS) , Barcelona , Spain
| | - María Francisca García-Garrido
- Institute of Neuropathology, Service of Pathologic Anatomy, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat , Barcelona , Spain
| | - Anusha Konetti
- Institute of Neuropathology, Service of Pathologic Anatomy, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat , Barcelona , Spain
| | - Franc Llorens
- Department of Neurology, Clinical Dementia Center, University Medical School, Georg-August University, German Center for Neurodegenerative Diseases (DZNE) , Göttingen , Germany
| | - Saima Zafar
- Department of Neurology, Clinical Dementia Center, University Medical School, Georg-August University, German Center for Neurodegenerative Diseases (DZNE) , Göttingen , Germany
| | - Margarita Carmona
- Institute of Neuropathology, Service of Pathologic Anatomy, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain; CIBERNED, Network Centre for Biomedical Research of Neurodegenerative Diseases, Institute Carlos III, Madrid, Spain
| | - José Antonio Del Rio
- CIBERNED, Network Centre for Biomedical Research of Neurodegenerative Diseases, Institute Carlos III, Madrid, Spain; Molecular and Cellular Neurobiotechnology, Department of Cell Biology, Institute of Bioengineering of Catalonia (IBEC), Parc Científic de Barcelona, University of Barcelona, Barcelona, Spain
| | - Inga Zerr
- Department of Neurology, Clinical Dementia Center, University Medical School, Georg-August University, German Center for Neurodegenerative Diseases (DZNE) , Göttingen , Germany
| | - Ellen Gelpi
- Neurological Tissue Bank of the Biobanc-Hospital Clínic-Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS) , Barcelona , Spain
| | - Isidro Ferrer
- Institute of Neuropathology, Service of Pathologic Anatomy, IDIBELL-Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain; CIBERNED, Network Centre for Biomedical Research of Neurodegenerative Diseases, Institute Carlos III, Madrid, Spain; Department of Pathology and Experimental Therapeutics, L'Hospitalet de Llobregat, University of Barcelona, Barcelona, Spain
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Fyrberg A, Lotfi K. Nucleoside Analog Activity in Malignant Melanoma Cell Lines. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2016; 34:639-49. [PMID: 26252632 DOI: 10.1080/15257770.2015.1047029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Mitochondrial deoxyguanosine kinase (dGK), is an enzyme responsible for activation of nucleoside analogs (NAs) to phosphorylated compounds which exert profound cytotoxicity, especially in hematological malignancies. Screening malignant melanoma cell lines against NAs revealed high sensitivity to several of them. This was believed to be due to the high levels of dGK expression in these cells. Downregulation of dGK in the melanoma cell line RaH5 using siRNA did not cause resistance to NAs as expected, but instead cells became more sensitive. This was probably partly due to the increased activity of another mitochondrial enzyme, thymidine kinase 2, seen in transfected cells.
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Affiliation(s)
- Anna Fyrberg
- a Centre for Biomedical Resources , Linköping University , Linköping , Sweden
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[18F]CFA as a clinically translatable probe for PET imaging of deoxycytidine kinase activity. Proc Natl Acad Sci U S A 2016; 113:4027-32. [PMID: 27035974 DOI: 10.1073/pnas.1524212113] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Deoxycytidine kinase (dCK), a rate-limiting enzyme in the cytosolic deoxyribonucleoside (dN) salvage pathway, is an important therapeutic and positron emission tomography (PET) imaging target in cancer. PET probes for dCK have been developed and are effective in mice but have suboptimal specificity and sensitivity in humans. To identify a more suitable probe for clinical dCK PET imaging, we compared the selectivity of two candidate compounds-[(18)F]Clofarabine; 2-chloro-2'-deoxy-2'-[(18)F]fluoro-9-β-d-arabinofuranosyl-adenine ([(18)F]CFA) and 2'-deoxy-2'-[(18)F]fluoro-9-β-d-arabinofuranosyl-guanine ([(18)F]F-AraG)-for dCK and deoxyguanosine kinase (dGK), a dCK-related mitochondrial enzyme. We demonstrate that, in the tracer concentration range used for PET imaging, [(18)F]CFA is primarily a substrate for dCK, with minimal cross-reactivity. In contrast, [(18)F]F-AraG is a better substrate for dGK than for dCK. [(18)F]CFA accumulation in leukemia cells correlated with dCK expression and was abrogated by treatment with a dCK inhibitor. Although [(18)F]CFA uptake was reduced by deoxycytidine (dC) competition, this inhibition required high dC concentrations present in murine, but not human, plasma. Expression of cytidine deaminase, a dC-catabolizing enzyme, in leukemia cells both in cell culture and in mice reduced the competition between dC and [(18)F]CFA, leading to increased dCK-dependent probe accumulation. First-in-human, to our knowledge, [(18)F]CFA PET/CT studies showed probe accumulation in tissues with high dCK expression: e.g., hematopoietic bone marrow and secondary lymphoid organs. The selectivity of [(18)F]CFA for dCK and its favorable biodistribution in humans justify further studies to validate [(18)F]CFA PET as a new cancer biomarker for treatment stratification and monitoring.
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Ansoleaga B, Jové M, Schlüter A, Garcia-Esparcia P, Moreno J, Pujol A, Pamplona R, Portero-Otín M, Ferrer I. Deregulation of purine metabolism in Alzheimer's disease. Neurobiol Aging 2014; 36:68-80. [PMID: 25311278 DOI: 10.1016/j.neurobiolaging.2014.08.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 08/05/2014] [Indexed: 12/30/2022]
Abstract
The neuroprotective role of adenosine and the deregulation of adenosine receptors in Alzheimer's disease (AD) have been extensively studied in recent years. However, little is known about the involvement of purine metabolism in AD. We started by analyzing gene expression in the entorhinal cortex of human controls and AD cases with whole-transcript expression arrays. Once we identified deregulation of the cluster purine metabolism, messenger RNA expression levels of 23 purine metabolism genes were analyzed with qRT-PCR in the entorhinal cortex, frontal cortex area 8, and precuneus at stages I-II, III-IV, and V-VI of Braak and Braak and controls. APRT, DGUOK, POLR3B, ENTPD3, AK5, NME1, NME3, NME5, NME7, and ENTPD2 messenger RNAs were deregulated, with regional variations, in AD cases when compared with controls. In addition, liquid chromatography mass spectrometry based metabolomics in the entorhinal cortex identified altered levels of dGMP, glycine, xanthosine, inosine diphosphate, guanine, and deoxyguanosine, all implicated in this pathway. Our results indicate stage- and region-dependent deregulation of purine metabolism in AD.
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Affiliation(s)
- Belén Ansoleaga
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Mariona Jové
- Department of Experimental Medicine, University of Lleida-Biomedical Research Institute of Lleida, Lleida, Spain
| | - Agatha Schlüter
- Neurometabolic Diseases Laboratory, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Paula Garcia-Esparcia
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Jesús Moreno
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, IDIBELL, L'Hospitalet de Llobregat, Spain; Centre for Biomedical Research on Rare Diseases (CIBERER), Institute Carlos III, Madrid, Spain; Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
| | - Reinald Pamplona
- Department of Experimental Medicine, University of Lleida-Biomedical Research Institute of Lleida, Lleida, Spain
| | - Manuel Portero-Otín
- Department of Experimental Medicine, University of Lleida-Biomedical Research Institute of Lleida, Lleida, Spain
| | - Isidre Ferrer
- Institute of Neuropathology, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Spain; University of Barcelona, Bellvitge Campus, L'Hospitalet de Llobregat, Spain; Centre for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED), Institute Carlos III, Madrid, Spain.
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8
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Ronchi D, Garone C, Bordoni A, Gutierrez Rios P, Calvo SE, Ripolone M, Ranieri M, Rizzuti M, Villa L, Magri F, Corti S, Bresolin N, Mootha VK, Moggio M, DiMauro S, Comi GP, Sciacco M. Next-generation sequencing reveals DGUOK mutations in adult patients with mitochondrial DNA multiple deletions. Brain 2012; 135:3404-15. [PMID: 23043144 DOI: 10.1093/brain/aws258] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The molecular diagnosis of mitochondrial disorders still remains elusive in a large proportion of patients, but advances in next generation sequencing are significantly improving our chances to detect mutations even in sporadic patients. Syndromes associated with mitochondrial DNA multiple deletions are caused by different molecular defects resulting in a wide spectrum of predominantly adult-onset clinical presentations, ranging from progressive external ophthalmoplegia to multi-systemic disorders of variable severity. The mutations underlying these conditions remain undisclosed in half of the affected subjects. We applied next-generation sequencing of known mitochondrial targets (MitoExome) to probands presenting with adult-onset mitochondrial myopathy and harbouring mitochondrial DNA multiple deletions in skeletal muscle. We identified autosomal recessive mutations in the DGUOK gene (encoding mitochondrial deoxyguanosine kinase), which has previously been associated with an infantile hepatocerebral form of mitochondrial DNA depletion. Mutations in DGUOK occurred in five independent subjects, representing 5.6% of our cohort of patients with mitochondrial DNA multiple deletions, and impaired both muscle DGUOK activity and protein stability. Clinical presentations were variable, including mitochondrial myopathy with or without progressive external ophthalmoplegia, recurrent rhabdomyolysis in a young female who had received a liver transplant at 9 months of age and adult-onset lower motor neuron syndrome with mild cognitive impairment. These findings reinforce the concept that mutations in genes involved in deoxyribonucleotide metabolism can cause diverse clinical phenotypes and suggest that DGUOK should be screened in patients harbouring mitochondrial DNA deletions in skeletal muscle.
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Affiliation(s)
- Dario Ronchi
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation, University of Milan, Neurology Unit, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy.
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9
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Leung GPH. Iatrogenic mitochondriopathies: a recent lesson from nucleoside/nucleotide reverse transcriptase inhibitors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 942:347-69. [PMID: 22399431 DOI: 10.1007/978-94-007-2869-1_16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The use of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) has revolutionized the treatment of infection by human immunodeficiency virus (HIV) and hepatitis-B virus. NRTIs can suppress viral replication in the long-term, but possess significant toxicity that can seriously compromise treatment effectiveness. The major toxicity of NRTIs is mitochondrial toxicity. This manifests as serious side effects such as myopathy, peripheral neuropathy and lactic acidosis. In general, it is believed that the mitochondrial pathogenesis is closely related to the effect of NRTIs on mitochondrial DNA polymerase-γ. Depletion and mutation of mitochondrial DNA during chronic NRTI therapy may lead to cellular respiratory dysfunction and release of reactive oxidative species, resulting in cellular damage. It is now apparent that the etiology is far more complex than originally thought. It appears to involve multiple mechanisms as well as host factors such as HIV per se, inborn mitochondrial mutation, and sex. Management of mitochondrial toxicity during NRTI therapy remains a challenge. Interruption of NRTI therapy and substitution of the causative agents with alternative better-tolerated NRTIs represents the mainstay of management for mitochondrial toxicity and its clinical manifestations. A range of pharmacological approaches has been proposed as treatments and prophylaxes.
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Affiliation(s)
- George P H Leung
- Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China.
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Leung GPH, Tse CM. The role of mitochondrial and plasma membrane nucleoside transporters in drug toxicity. Expert Opin Drug Metab Toxicol 2008; 3:705-18. [PMID: 17916056 DOI: 10.1517/17425255.3.5.705] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many anticancer and antiviral drugs are nucleoside analogues, which interfere with nucleotide metabolism and DNA replication to produce pharmacological effects. Clinical efficacy and toxicity of nucleoside drugs are closely associated with nucleoside transporters because they mediate the transport of nucleoside drugs across biological membranes. Two families of human nucleoside transporters (equilibrative nucleoside transporters and concentrative nucleoside transporters) have been extensively studied for several decades. They are widely distributed, from the plasma membrane to membranes of organelles such as mitochondria, and the distribution differs in different tissues. In addition, they have different specificities to nucleoside drugs. The characteristics of equilibrative and concentrative nucleoside transporters affect the therapeutic outcomes achieved with anticancer and antiviral nucleoside drugs. In this review, an overview of the role of mitochondrial and plasma membrane nucleoside transporters in nucleoside drug toxicity is provided. Rational design and therapeutic application of nucleoside analogues are also discussed.
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Affiliation(s)
- George P H Leung
- The University of Hong Kong, Department of Pharmacology, Hong Kong.
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Abstract
Liver involvement, a common feature in childhood mitochondrial hepatopathies, particularly in the neonatal period, may manifest as neonatal acute liver failure, hepatic steatohepatitis, cholestasis, or cirrhosis with chronic liver failure of insidious onset. There are usually significant neuromuscular symptoms, multisystem involvement, and lactic acidemia. The liver disease is usually progressive and eventually fatal. Current medical therapy of mitochondrial hepatopathies is largely ineffective, and the prognosis is usually poor. The role of liver transplantation in patients with liver failure remains poorly defined because of the systemic nature of the disease that does not respond to transplantation. Several specific molecular defects (mutations in nuclear genes such as SCO1, BCS1L, POLG, DGUOK, and MPV17 and deletion or rearrangement of mitochondrial DNA) have been identified in recent years. Prospective, longitudinal multicenter studies will be needed to address the gaps in our knowledge in these rare liver diseases.
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Affiliation(s)
- Way S Lee
- Department of Paediatrics, University of Malaya Medical Centre, Kuala Lumpur, Malaysia
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12
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Abstract
Hepatic involvement is a common feature in childhood mitochondrial hepatopathies, particularly in the neonatal period. Respiratory chain disorders may present as neonatal acute liver failure, hepatic steatohepatitis, cholestasis, or cirrhosis with chronic liver failure of insidious onset. In recent years, specific molecular defects (mutations in nuclear genes such as SCO1, BCS1L, POLG, DGUOK, and MPV17 and the deletion or rearrangement of mitochondrial DNA) have been identified, with the promise of genetic and prenatal diagnosis. The current treatment of mitochondrial hepatopathies is largely ineffective, and the prognosis is generally poor. The role of liver transplantation in patients with liver failure remains poorly defined because of the systemic nature of the disease, which does not respond to transplantation. Prospective, longitudinal, multicentered studies will be needed to address the gaps in our knowledge in these rare liver diseases.
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Affiliation(s)
- Way S Lee
- Department of Paediatrics, University of Malaya Medical Centre, Kuala Lumpur, Malaysia
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Barroso JF, Elholm M, Flatmark T. Tight binding of deoxyribonucleotide triphosphates to human thymidine kinase 2 expressed in Escherichia coli. Purification and partial characterization of its dimeric and tetrameric forms. Biochemistry 2004; 42:15158-69. [PMID: 14690426 DOI: 10.1021/bi035230f] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human thymidine kinase 2 (hTK2) phosphorylates pyrimidine deoxyribonucleosides to the corresponding nucleoside monophosphates, using a nucleotide triphosphate as a phosphate donor. In this study, hTK2 was cloned and expressed at high levels in Escherichia coli as a fusion protein with maltose-binding protein. Induction of a heat-shock response by ethanol and coexpression of plasmid-encoded GroEL/ES chaperonins at 28 degrees C minimized the nonspecific aggregation of the hybrid protein and improved the recovery of three homooligomeric forms of the properly folded enzyme, i.e., dimer > tetramer > hexamer. The dimer and the tetramer were isolated in stable and highly purified forms after proteolytic removal of the fusion partner. Both oligomers contained a substoichiometric amount of deoxyribonucleotide triphosphates (dTTP > dCTP > dATP), known to be strong feedback inhibitors of the enzyme. Steady-state kinetic studies were consistent with the presence of endogenous inhibitors, and both oligomeric forms revealed a lag phase of at least approximately 5 min, which was abolished on preincubation with substrate (dThd or dCyd). The rather similar kinetic properties of the two oligomeric forms indicate that the basic functional unit is a dimer. Molecular docking experiments with a modeled hTK2 three-dimensional structure accurately predicted the binding positions at the active site of the natural substrates (dThd, dCyd, and ATP) and inhibitors (dTTP and dCTP), with highly conserved orientations obtained for all ligands. The calculated relative nonbonded interaction energies are in agreement with the biochemical data and show that the inhibitor complexes have lower stabilization energies (higher affinity) than the substrates.
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Affiliation(s)
- João Filipe Barroso
- Department of Biochemistry and Molecular Biology, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway
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Van Rompay AR, Johansson M, Karlsson A. Substrate specificity and phosphorylation of antiviral and anticancer nucleoside analogues by human deoxyribonucleoside kinases and ribonucleoside kinases. Pharmacol Ther 2003; 100:119-39. [PMID: 14609716 PMCID: PMC7126524 DOI: 10.1016/j.pharmthera.2003.07.001] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Structural analogues of nucleosides, nucleoside analogues (NA), are used in the treatment of cancer and viral infections. Antiviral NAs inhibit replication of the viral genome, whereas anticancer NAs inhibit cellular DNA replication and repair. NAs are inactive prodrugs that are dependent on intracellular phosphorylation to their pharmacologically active triphosphate form. The deoxyribonucleoside kinases (dNK) and ribonucleoside kinases (rNK) catalyze the first phosphorylation step, converting deoxyribonucleosides and ribonucleosides to their corresponding monophosphate form. The dNKs have been studied intensively, whereas the rNKs have not been as thoroughly investigated. This overview is focused on the substrate specificity, tissue distribution, and subcellular location of the mammalian dNKs and rNKs and their role in the activation of NAs.
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Key Words
- antiviral therapy
- anticancer therapy
- chemotherapy
- nucleoside analogue
- deoxyribonucleoside kinase
- ribonucleoside kinase
- adk, adenosine kinase
- aids, aquired immunodeficiency syndrome
- arac, 1-β-d-arabinofuranosylcytosine (cytarabine)
- arag, 9-β-d-arabinofuranosylguanine (nelarabine)
- azt, 3′-azido-2′,3′-dideoxythymidine (zidovudine)
- cafda, 2-chloro-2′-fluoro-9-β-d-arabinofuranosyladenine (clofarabine)
- cda, 2-chloro-2′-deoxyadenosine (cladribine)
- dck, deoxycytidine kinase
- ddc, 2′,3′-dideoxycytidine (zalcitabine)
- ddi, 2′,3′-dideoxyinosine (didanosine)
- dgk, deoxyguanosine kinase
- dfdc, 2′,2′-difluorodeoxycytidine (gemcitabine)
- dnk, deoxyribonucleoside kinase
- d4t, 2′,3′-didehydro-3′-deoxythymidine (stavudine)
- f-araa, 2-fluoro-9-β-d-arabinofuranosyladenine (fludarabine)
- fda, food and drug administration
- fiau, 1-(2′-deoxy-2′-fluoro-β-d-arabinofuranosyl)-5-iodouracil (fialuridine)
- hbv, hepatitis b virus
- mtdna, mitochondrial dna
- hiv, human immunodeficiency virus
- na, nucleoside analogue
- ndpk, nucleoside diphosphate kinase
- nmpk, nucleoside monophosphate kinase
- 5′-nt, 5′-nucleotidase
- rnk, ribonucleoside kinase
- rr, ribonucleotide reductase
- rt, reverse transcriptase
- tk1, thymidine kinase 1
- tk2, thymidine kinase 2
- uck1, uridine-cytidine kinase 1
- uck2, uridine-cytidine kinase 2
- 3tc, 2′-deoxy-3′-thiacytidine (lamivudine)
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Affiliation(s)
- An R Van Rompay
- Department of Nephrology-Hypertension, University of Antwerp, 2610 Antwerp, Belgium
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15
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Abstract
Although non-specific gastrointestinal and hepatic symptoms are commonly found in most mitochondrial disorders, they are among the cardinal manifestations of several primary mitochondrial diseases, such as: mitochondrial neurogastrointestinal encephalomyopathy; mitochondrial DNA depletion syndrome; Alpers syndrome; and Pearson syndrome. Management of these heterogeneous disorders includes the empiric supplementation with various "mitochondrial cocktails," supportive therapies, and avoidance of drugs and conditions known to have a detrimental effect on the respiratory chain. There is a great need for improved methods of treatment and controlled clinical trials of existing therapies. Liver transplantation is successful in acquired cases; however neuromuscular involvement in primary mitochondrial disorders should be a contraindication for liver transplantation.
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Affiliation(s)
- Lynette A Gillis
- Division of Gastroenterology and Nutrition, Department of Pediatrics, University of Pennsylvania School of Medicine, Children's Hospital of Philadelphia, 34th St. and Civic Center, Blvd., Philadelphia, PA 19104, USA
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16
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Charlap JH, Donahue RJ, Knudsen TB. Exposure-disease continuum for 2-chloro-2'-deoxyadenosine, a prototype ocular teratogen. 3. Intervention with PK11195. BIRTH DEFECTS RESEARCH. PART A, CLINICAL AND MOLECULAR TERATOLOGY 2003; 67:108-15. [PMID: 12769506 DOI: 10.1002/bdra.10026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Treatment of pregnant mice with 2-chloro-2'-deoxyadenosine (2CdA) on Day 8 of gestation induces microphthalmia through a mechanism linked to the p53 tumor suppressor pathway. The present study defines the response of Day 8 mouse embryos through time with respect to pharmacologic intervention with PK11195, a ligand of the mitochondrial peripheral benzodiazepine receptor (Bzrp). METHODS Pregnant CD-1 mice dosed with 2CdA with or without PK11195 on gestation Day 8 provided fetuses for teratologic evaluation on Day 14 and Day 17; HPLC measured pyridine nucleotides (NADH/NAD+) at 1.5 hr, RT-PCR measured mitochondrial 16S rRNA abundance at 3.0 hr, and p53 protein induction was assessed with immunostaining at 4.5 hr postexposure. RESULTS The mean incidences of malformed fetuses were significantly higher in the 7.5 mg/kg 2CdA treatment group (50.2% malformed) vs. the 2CdA + 4.0 mg/kg PK11195 co-treatment group (4.4% malformed). Malformed fetuses displayed a range of ocular defects that included microphthalmia and keratolenticular dysgenesis (Peters anomaly). No malformations were observed in the control or PK11195 alone groups. PK11195 also protected litters from increased resorption rates and fetal weight reduction. It did not rescue early effects on NADH balance (1.5 hr) or 16S rRNA expression (3.0 hr); however, the p53 response (4.5 hr) was downgraded in 2CdA + PK11195 embryos vs. 2CdA alone. By delaying the administration of PK11195 in 1.5 hr intervals it was determined that the window for protection closed between 4.5 to 6.0 hr after 2CdA. CONCLUSIONS The capacity of PK11195 to suppress the pathogenesis of microphthalmia implies a critical role for mitochondrial peripheral benzodiazepine receptors in the p53-dependent mode of action of 2CdA on ocular development.
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Affiliation(s)
- Jeffrey H Charlap
- Department of Pathology, Anatomy and Cell Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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17
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Månsson E, Flordal E, Liliemark J, Spasokoukotskaja T, Elford H, Lagercrantz S, Eriksson S, Albertioni F. Down-regulation of deoxycytidine kinase in human leukemic cell lines resistant to cladribine and clofarabine and increased ribonucleotide reductase activity contributes to fludarabine resistance. Biochem Pharmacol 2003; 65:237-47. [PMID: 12504799 DOI: 10.1016/s0006-2952(02)01484-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mechanisms of acquired resistance to three purine analogues, 2-chloro-2'-deoxyadenosine (cladribine, CdA), 9-beta-D-arabinofuranosyl-2-fluoroadenine (fludarabine, Fara-A), and 2-chloro-2'-arabino-fluoro-2'-deoxyadenosine (clofarabine, CAFdA) were investigated in a human T-lymphoblastic leukemia cell line (CCRF-CEM). These analogues are pro-drugs and must be activated by deoxycytidine kinase (dCK). The CdA and CAFdA resistant cell lines exhibited increased resistance to the other nucleoside analogues activated by dCK. This was also the case for the Fara-A resistant cells, except that they were sensitive to CAFdA and guanosine analogues. The CdA and CAFdA resistant cells displayed a deficiency in dCK activity (to <5%) while the Fara-A resistant cells showed only a minor reduction of dCK activity (20% reduction). The activity of high K(m) 5'-nucleotidase (5'-NT) (cN-II) using IMP as substrate, was 2-fold elevated in the resistant cell lines. The amount of the small subunit R2 of ribonucleotide reductase (RR) was higher in the Fara-A resistant cells, which translated into a higher RR activity, while CdA and CAFdA cells had decreased activity compared to the parental cells. Expression of the recently identified RR subunit, p53R2 full-size protein, in CAFdA cells was low compared to parental cells, but a protein of lower molecular weight was detected in CdA and CAFdA cells. Co-incubation of Fara-A with the RR inhibitor 3,4-dihydroxybenzohydroxamic acid (didox) enhanced cytotoxicity in the Fara-A resistant cells by a factors of 20. Exposure of the cells to the nucleoside analogues studied here also caused structural and numerical instability of the chromosomes; the most profound changes were recorded for CAFdA cells, as demonstrated by SKY and CGH analysis. We conclude that down-regulation of dCK in cells resistant to CdA and CAFdA and increased activity of RR in cells resistant to Fara-A contribute to resistance.
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Affiliation(s)
- Emma Månsson
- Department of Medicine, Division of Clinical Pharmacology, Karolinska Hospital, SE-17176 Stockholm, Sweden
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18
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Taanman JW, Kateeb I, Muntau AC, Jaksch M, Cohen N, Mandel H. A novel mutation in the deoxyguanosine kinase gene causing depletion of mitochondrial DNA. Ann Neurol 2002; 52:237-9. [PMID: 12210798 DOI: 10.1002/ana.10247] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Recently, a homozygous single-nucleotide deletion in exon 2 of the deoxyguanosine kinase gene (DGUOK) was identified as the disease-causing mutation in 3 apparently unrelated Israeli-Druze families with depleted hepatocerebral mitochondrial DNA. We have discovered a novel homozygous nonsense mutation in exon 3 of DGUOK (313C-->T) from a patient born to nonconsanguineous German parents. This finding shows that mutations in DGUOK causing mitochondrial DNA depletion are not confined to a single ethnic group.
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Affiliation(s)
- Jan-Willem Taanman
- University Department of Clinical Neurosciences, Royal Free and University College Medical School, University College London, London, United Kingdom.
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19
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Lau C, Narotsky MG, Lui D, Best D, Setzer RW, Mann PC, Wubah JA, Knudsen TB. Exposure-disease continuum for 2-chloro-2'-deoxyadenosine (2-CdA), a prototype teratogen: induction of lumbar hernia in the rat and species comparison for the teratogenic responses. TERATOLOGY 2002; 66:6-18. [PMID: 12115775 DOI: 10.1002/tera.10039] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND The purine analog 2-chloro-2'-deoxyadenosine (2-CdA) caused ocular and limb defects in the mouse and rabbit. The current study examined the teratogenic potential of this drug in the rat and compared the adverse developmental outcomes with the other species. METHODS Timed-pregnant Sprague-Dawley rats were given a single intraperitoneal injection of various doses of 2-CdA ranging from 5-60 mg/kg, at gestational day (GD) 9.5 and GD 14. 2-CdA concentrations in maternal serum and embryos were measured by HPLC and termed fetuses were prepared for teratological examination. RESULTS Full-litter resorption was seen in dams receiving 50 mg/kg of 2-CdA at GD 9.5, whereas post-implantation loss was significantly increased and fetal weights significantly reduced at 40 mg/kg. Gross examination of the surviving fetuses revealed microphthalmia, a shortened body trunk and lumbar hernia, manifested by a soft mass protrusion at the lumbar region on one or both sides of the spine. Incidence of these defects increased in a dose-dependent fashion. Histological examination indicated that the hernia was associated with hypoplasia of the body wall, poorly developed skeletal muscle bundles surrounding the vertebral column in the lumbar region, and an absence of the lateral muscle groups that allowed protrusion of the abdominal viscera. The lumbar hernia was generally accompanied by spina bifida, deformed ribs and a wide spectrum of soft tissue-abnormalities that included kidney, genitourinary and heart defects. At GD 14, exposure to 2-CdA at 60 mg/kg produced oligodactyly in one of six litters. CONCLUSIONS 2-CdA produced similar ocular defects in the rat and mouse, although the incidence was much lower in the former species. In contrast, the drug-induced lumbar hernia was only seen in the rat. These apparent disparities were not readily explained by species differences in pharmacokinetic parameters. the similarities between the teratological features of 2-CdA-induced lumbar hernia in the rat and the clinical description of lumbocostovertebral syndrome, however, may provide a key to unlock the etiology of this rare birth defect in humans.
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Affiliation(s)
- Christopher Lau
- Reproductive Toxicology Division, NHEERL, ORD, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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20
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Lotfi K, Månsson E, Peterson C, Eriksson S, Albertioni F. Low level of mitochondrial deoxyguanosine kinase is the dominant factor in acquired resistance to 9-beta-D-arabinofuranosylguanine cytotoxicity. Biochem Biophys Res Commun 2002; 293:1489-96. [PMID: 12054684 DOI: 10.1016/s0006-291x(02)00415-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
9-beta-D-arabinofuranosylguanine (Ara-G) is an important and relatively new guanosiue analog with activity in patients with T-cell malignancies. The biochemical and molecular events leading to resistance to Ara-G are not fully understood. Therefore we generated two Ara-G-resistant human MOLT-4 leukemic cell lines with different levels of resistance. The mitochondrial enzyme deoxyguanosine kinase (dGK) and the nuclear/cytosol enzyme deoxycytidine kinase (dCK) are key enzymes in the activation of Ara-G. Decreased levels of dGK protein and mRNA were found in both resistant cell sublines. The activity of dCK was decreased in the subline with higher resistance to Ara-G and these cells were highly cross-resistant to other nucleosides activated by dCK. Increased activity of the mitochondrial enzyme thymidine kinase 2 was observed in both resistant sublines and this could be related to the dGK deficiency. In search for other resistance mechanisms it was found that the resistant cells overexpress the mdr1 gene, while no changes were detected in the levels of multidrug resistance-associated protein 1 through 6, lung resistance-associated protein or topoisomerase IIalpha or IIbeta. Taken together, our findings demonstrate that multiple mechanisms are involved in the acquired resistance to Ara-G. However, low expression of dGK is the most apparent alteration in both resistant cell lines. Partial deficiency of dCK was found in the subline cells with higher resistance to Ara-G. Furthermore, Ara-G may select for high expression of the multidrug resistance (mdr1) which could be a specific resistance mechanism but more likely part of an overall cellular stress response.
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Affiliation(s)
- Kourosh Lotfi
- Department of Medicine and Care, Division of Clinical Pharmacology, Faculty of Health Sciences, Linköping, SE-581 85, Sweden
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21
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Knecht W, Sandrini MP, Johansson K, Eklund H, Munch-Petersen B, Piškur J. A few amino acid substitutions can convert deoxyribonucleoside kinase specificity from pyrimidines to purines. EMBO J 2002; 21:1873-80. [PMID: 11927571 PMCID: PMC125940 DOI: 10.1093/emboj/21.7.1873] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In mammals, the four native deoxyribonucleosides are phosphorylated to the corresponding monophosphates by four deoxyribonucleoside kinases, which have specialized substrate specificities. These four enzymes are likely to originate from a common progenitor kinase. Insects appear to have only one multisubstrate deoxyribonucleoside kinase (dNK, EC 2.7.1.145), which prefers pyrimidine nucleosides, but can also phosphorylate purine substrates. When the structures of the human deoxyguanosine kinase (dGK, EC 2.7.1.113) and the dNK from Drosophila melanogaster were compared, a limited number of amino acid residues were identified and proposed to be responsible for the substrate specificity. Three of these key residues in Drosophila dNK were then mutagenized and the mutant enzymes were characterized regarding their ability to phosphorylate native deoxyribonucleosides and nucleoside analogs. The mutations converted the dNK substrate specificity from predominantly pyrimidine specific into purine specific. A similar scenario could have been followed during the evolution of kinases. Upon gene duplication of the progenitor kinase, only a limited number of single amino acid changes has taken place in each copy and resulted in substrate-specialized enzymes.
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Affiliation(s)
- Wolfgang Knecht
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark and Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden Corresponding author e-mail:
| | - Michael P.B. Sandrini
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark and Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden Corresponding author e-mail:
| | - Kenth Johansson
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark and Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden Corresponding author e-mail:
| | - Hans Eklund
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark and Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden Corresponding author e-mail:
| | - Birgitte Munch-Petersen
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark and Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden Corresponding author e-mail:
| | - Jure Piškur
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Department of Life Sciences and Chemistry, Roskilde University, DK-4000 Roskilde, Denmark and Department of Molecular Biology, Swedish University of Agricultural Sciences, Box 590, Biomedical Center, S-751 24 Uppsala, Sweden Corresponding author e-mail:
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22
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Månsson E, Liliemark E, Söderhäll S, Gustafsson G, Eriksson S, Albertioni F. Real-time quantitative PCR assays for deoxycytidine kinase, deoxyguanosine kinase and 5'-nucleotidase mRNA measurement in cell lines and in patients with leukemia. Leukemia 2002; 16:386-92. [PMID: 11896543 DOI: 10.1038/sj.leu.2402388] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2001] [Accepted: 11/14/2001] [Indexed: 11/09/2022]
Abstract
The relative levels of the deoxycytidine kinase (dCK), deoxyguanosine kinase (dGK), and the 5'-nucleotidase (5'-NT) are of importance for the effect of many nucleoside analogues used in the treatment of hematological malignancies. To elucidate dCK, dGK and 5'-NT gene expressions in cell lines and in samples from patients with leukemia, we have established a real-time quantitative PCR (RQ-PCR) method. From the available dCK, dGK and 5'-NT cDNA sequences we designed specific primers and fluorogenic probes for the respective genes. The mRNA of dCK, dGK and 5'-NT was also measured by semi-quantitative RT-PCR, the enzyme activities by a radioactive substrate-based technique and Western blot was used to measure the amount of dCK and dGK protein. A MOLT-4 wild-type and its 9-beta-D-arabinofuranosylguanine (Ara-G)-resistant subline was used for the methods comparisons and the RQ-PCR assay was used in 35 samples from pediatric patients with ALL and AML. The results from RQ-PCR for the cell lines were in agreement with the semi-quantitative RT-PCR. The mRNA expression for dCK, dGK and 5'-NT (expressed as the ratio of the respective gene and the reference gene) in pediatric ALL and AML patients showed a large interindividual variability from 0.06 to 2.34, non-detectable to 0.06 and 0.04 to 0.30, respectively. These results show that the quantitative evaluation by RQ-PCR is a valuable tool in the determination of dCK, dGK and 5'-NT mRNA levels in cell lines and in clinical samples which were expressed at various levels. This rapid, convenient and specific method is suitable for further studies of these genes in clinical samples.
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Affiliation(s)
- E Månsson
- Department of Medicine, Division of Clinical Pharmacology, Karolinska Hospital, Stockholm, Sweden
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23
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Knecht W, Petersen GE, Munch-Petersen B, Piskur J. Deoxyribonucleoside kinases belonging to the thymidine kinase 2 (TK2)-like group vary significantly in substrate specificity, kinetics and feed-back regulation. J Mol Biol 2002; 315:529-40. [PMID: 11812127 DOI: 10.1006/jmbi.2001.5257] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In eukaryotic cells deoxyribonucleoside kinases belonging to three phylogenetic sub-families have been found: (i) thymidine kinase 1 (TK1)-like enzymes, which are strictly pyrimidine deoxyribonucleoside-specific kinases; (ii) TK2-like enzymes, which include pyrimidine deoxyribonucleoside kinases and a single multisubstrate kinase from Drosophila melanogaster (Dm-dNK); and (iii) deoxycytidine/deoxyguanosine kinase (dCK/dGK)-like enzymes, which are deoxycytidine and/or purine deoxyribonucleoside-specific kinases. We cloned and characterized two new deoxyribonucleoside kinases belonging to the TK2-like group from the insect Bombyx mori and the amphibian Xenopus laevis. The deoxyribonucleoside kinase from B. mori (Bm-dNK) turned out to be a multisubstrate kinase like Dm-dNK. But uniquely for a deoxyribonucleoside kinase, Bm-dNK displayed positive cooperativity with all four natural deoxyribonucleoside substrates. The deoxyribonucleoside kinase from X. laevis (Xen-PyK) resembled closely the human and mouse TK2 enzymes displaying their characteristic Michaelis-Menten kinetic with deoxycytidine and negative cooperativity with its second natural substrate thymidine. Bm-dNK, Dm-dNK and Xen-PyK were shown to be homodimers. Significant differences in the feedback inhibition by deoxyribonucleoside triphosphates between these three enzymes were found. The insect multisubstrate deoxyribonucleoside kinases Bm-dNK and Dm-dNK were only inhibited by thymidine triphosphate, while Xen-PyK was inhibited by thymidine and deoxycytidine triphosphate in a complex pattern depending on the deoxyribonucleoside substrate. The broad substrate specificity and different feedback regulation of the multisubstrate insect deoxyribonucleoside kinases may indicate that these enzymes have a different functional role than the other members of the TK2-like group.
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Affiliation(s)
- Wolfgang Knecht
- Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, Lyngby, DK 2800, Denmark.
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24
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Mandel H, Szargel R, Labay V, Elpeleg O, Saada A, Shalata A, Anbinder Y, Berkowitz D, Hartman C, Barak M, Eriksson S, Cohen N. The deoxyguanosine kinase gene is mutated in individuals with depleted hepatocerebral mitochondrial DNA. Nat Genet 2001; 29:337-41. [PMID: 11687800 DOI: 10.1038/ng746] [Citation(s) in RCA: 438] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondrial DNA (mtDNA)-depletion syndromes (MDS; OMIM 251880) are phenotypically heterogeneous, autosomal-recessive disorders characterized by tissue-specific reduction in mtDNA copy number. Affected individuals with the hepatocerebral form of MDS have early progressive liver failure and neurological abnormalities, hypoglycemia and increased lactate in body fluids. Affected tissues show both decreased activity of the mtDNA-encoded respiratory chain complexes (I, III, IV, V) and mtDNA depletion. We used homozygosity mapping in three kindreds of Druze origin to map the gene causing hepatocerebral MDS to a region of 6.1 cM on chromosome 2p13, between markers D2S291 and D2S2116. This interval encompasses the gene (DGUOK) encoding the mitochondrial deoxyguanosine kinase (dGK). We identified a single-nucleotide deletion (204delA) within the coding region of DGUOK that segregates with the disease in the three kindreds studied. Western-blot analysis did not detect dGK protein in the liver of affected individuals. The main supply of deoxyribonucleotides (dNTPs) for mtDNA synthesis comes from the salvage pathway initiated by dGK and thymidine kinase-2 (TK2). The association of mtDNA depletion with mutated DGUOK suggests that the salvage-pathway enzymes are involved in the maintenance of balanced mitochondrial dNTP pools.
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Affiliation(s)
- H Mandel
- Metabolic Disease Unit, Department of Pediatrics, Rambam Medical Center, Technion-Israel Institute of Technology, Bruce Rappaport Faculty of Medicine, Haifa, Israel
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25
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Månsson E, Jönsson K, Albertioni F. Identification and characterization of human deoxyguanosine kinase cDNA fragments. Cancer Lett 2001; 170:147-52. [PMID: 11463492 DOI: 10.1016/s0304-3835(01)00586-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Mitochondria require deoxyribonucleoside triphosphates for the synthesis of their DNA and one of the enzymes responsible for the initial phosphorylation of purine deoxyribonucleoside is deoxyguanosine kinase (dGK; EC 2.7.1.113). Recent studies have suggested that dGK in addition to deoxycytidine kinase phosphorylates several anti-cancer agents, such as 9-beta-D-arabinofuranosylguanine (Ara-G), cladribine (CdA), and fludarabine. There appear to coexist several mRNA fragments of dGK. In the present study we found 10 fragments, the longest fragment had 834bp, and represented the entire open reading frame of dGK (780bp). The nine additional fragments detected ranged from 807 to 269bp. All the fragments were found to contain the specific mitochondria translocation signal sequence. Expression of these fragments in Escherichia coli demonstrated that only the full-length dGK resulted in a protein that could phosphorylate CdA and Ara-G. Given the difficulty to measure the full-length dGK, these data are of value for studying the mRNA gene expression of dGK in cell lines and in leukemic cells from patients.
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Affiliation(s)
- E Månsson
- Department of Medicine, Division of Clinical Pharmacology, Karolinska Hospital, 171 76 Stockholm, Sweden
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26
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Wubah JA, Setzer RW, Lau C, Charlap JH, Knudsen TB. Exposure-disease continuum for 2-chloro-2'-deoxyadenosine, a prototype ocular teratogen. 1. Dose-response analysis. TERATOLOGY 2001; 64:154-69. [PMID: 11514946 DOI: 10.1002/tera.1059] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Treatment of pregnant mice with 2-chloro-2'-deoxyadenosine (2CdA) on day 8 of gestation induces microphthalmia through a mechanism coupled to the p53 tumor suppressor gene. The present study defines 2CdA dosimetry with respect to exposure (pharmacokinetics), p53 protein induction, and disease (microphthalmia). METHODS Pregnant CD-1 mice dosed with 0.5-10.0 mg/kg 2CdA on day 8 provided fetuses for teratological evaluation; 2CdA was measured by HPLC in the antimesometrium through 180 min postexposure, and p53 was assessed with immunostaining of the embryo through 270 min. 5'-/3'-RACE was used to sequence the candidate gene for 2CdA bioactivation from target cells. RESULTS Microphthalmia appeared first in the dose-response curve. The highest 2CdA dose having no observable adverse effect (NOAEL) was 1.5 mg/kg; the benchmark dose that produced an extra 5% risk of microphthalmia (BMD(5)) was 2.5 mg/kg, and the lower confidence limit (BMDL) was 2.0 mg/kg. Pharmacokinetic parameters for doses encompassing the threshold (1.5-2.5 mg/kg) were modeled at 1.0-1.8 microM (C(max)) and 30-80 microM-min (AUC). The p53 response was not detected below the BMDL; however, a low-grade response appeared 4.5 hr after a teratogenic dose (5.0 mg/kg), and high-grade induction followed an embryolethal dose (10.0 mg/kg). RACE identified a novel splice variant of mitochondrial deoxyguanosine kinase, dGK-3, as the likely candidate for 2CdA bioactivation in the embryo. CONCLUSIONS Microphthalmia represented the critical effect malformation of 2CdA. The findings suggest a mitochondrial mechanism for 2CdA bioactivation, leading to an embryonic p53 response only after 2CdA elimination and implying pharmacodynamic coupling to the exposure-disease continuum. Published 2001 Wiley-Liss, Inc.
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Affiliation(s)
- J A Wubah
- Department of Pathology, Anatomy and Cell Biology, Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA
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27
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Jüllig M, Eriksson S. Apoptosis induces efflux of the mitochondrial matrix enzyme deoxyguanosine kinase. J Biol Chem 2001; 276:24000-4. [PMID: 11294860 DOI: 10.1074/jbc.m100435200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Deoxyguanosine kinase (dGK) initiates the salvage of purine deoxynucleosides in mitochondria and is a key enzyme in mitochondrial DNA precursor synthesis. The active form of the enzyme is a 60-kDa protein normally located in the mitochondrial matrix. Here we describe the subcellular distribution of dGK during apoptosis in human epithelial kidney 293 cells and human lymphoblast Molt-4 cells. Immunological methods were used to monitor dGK as well as other mitochondrial proteins. Surprisingly, dGK was found to relocate to the cytosolic compartment at a similar rate as cytochrome c, a mitochondrial intermembraneous enzyme known to enter the cytosol early in apoptosis. The redistribution of dGK from the mitochondria to the cytosol may be of importance for the activation of apoptotic purine nucleoside cofactors such as dATP and demonstrates that mitochondrial matrix proteins may selectively leak out during apoptosis.
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Affiliation(s)
- M Jüllig
- Department of Veterinary Medical Chemistry, University of Agricultural Sciences, The Biomedical Centre, Box 575, S-751 23 Uppsala, Sweden.
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28
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Jacobsson B, Albertioni F, Eriksson S. Deoxynucleoside anabolic enzyme levels in acute myelocytic leukemia and chronic lymphocytic leukemia cells. Cancer Lett 2001; 165:195-200. [PMID: 11275369 DOI: 10.1016/s0304-3835(01)00430-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The deoxynucleoside kinase reaction is often rate-limiting in the anabolism of pharmacologically active anti-cancer nucleosides. The levels of thymidine kinase (TK), deoxycytidine kinase, deoxyguanosine kinase (dGK), and thymidylate kinase were determined in leukocyte extracts from patients with chronic lymphocytic leukemia (CLL) and acute myelocytic leukemia (AML). The extracts from AML patients showed significantly higher TK activity than the ones from CLL patients. There were no differences in the levels of the other three kinases. In the case of dGK, the determinations were carried out with both an immunoblotting assay and selective enzyme activity measurements.
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Affiliation(s)
- B Jacobsson
- Department of Infectious Diseases, Huddinge Hospital, SE-141 86, Huddinge, Sweden
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Herrström Sjöberg A, Wang L, Eriksson S. Antiviral guanosine analogs as substrates for deoxyguanosine kinase: implications for chemotherapy. Antimicrob Agents Chemother 2001; 45:739-42. [PMID: 11181353 PMCID: PMC90366 DOI: 10.1128/aac.45.3.739-742.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A highly active form of human recombinant deoxyguanosine kinase (dGK) phosphorylated purine nucleoside analogs active against cytomegalovirus, hepatitis B virus, and human immunodeficiency virus, such as penciclovir, 2',3'-dideoxyguanosine and 3'-fluoro-2',3'-dideoxyguanosine. The antiherpesvirus drug ganciclovir, which is also used in gene therapy, was a substrate for dGK, but with low efficiency. ATP and UTP were both good phosphate donors, with apparent K(m) values of 6 and 4 microM and V(max) values of 34 and 90 nmol of dGMP/mg of dGK/min, respectively. With a mixture of 5 mM ATP and 0.05 mM UTP, which represent physiologically relevant concentrations, the activities of dGK with ganciclovir and penciclovir was 1% and approximately 10%, respectively, of that with dGuo. The levels of dGK in different tissues were determined with a selective enzyme assay and the total activities per gram of tissues were similar in liver, brain, heart, and thymus extracts. The fact that the cellular dGK enzyme can phosphorylate antiviral guanosine analogs may help to explain the efficacies and side effects of several forms of chemotherapy.
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Affiliation(s)
- A Herrström Sjöberg
- Department of Veterinary Medical Chemistry, Swedish University of Agricultural Sciences, The Biomedical Center, SE-751 23 Uppsala, Sweden
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