Differential incorporation of 1‐β‐<scp>D</scp>‐arabinofuranosylcytosine and 9‐β‐<scp>D</scp>‐arabinofuranosylguanine into nuclear and mitochondrial DNA

Zhu, Changliang; Johansson, Magnus; Karlsson, Anna

doi:10.1016/s0014-5793(00)01569-6

Cited by 17 publications

(12 citation statements)

References 18 publications

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“…The relative rates of these diverse processes provide at equilibrium a much higher specific radioactivity for mt dGTP than for cytosolic dGTP. This probably explains why in previous autoradiographic experiments (35,36) deoxynucleosides phosphorylated by mt kinases preferentially labeled mt DNA.…”

Section: Discussionmentioning

confidence: 76%

“…For a long time the prevailing view was that specific kinases inside mitochondria form mt dNTPs, whereas de novo synthesis by ribonucleotide reductase provides cytosolic dNTPs, with the two pools separated by the mt membrane. Autoradiographic observations (35,36) had shown specific labeling of mt DNA from deoxynucleosides, and metabolic experiments claimed depletion of cytosolic but not of mt dTTP after inhibition with amethopterin (37). Support also came from the discovery that in humans genetic deletion of intra-mt deoxynucleoside kinase activity results in depletion of mt DNA (4,5).…”

Section: Discussionmentioning

confidence: 99%

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Metabolic Interrelations within Guanine Deoxynucleotide Pools for Mitochondrial and Nuclear DNA Maintenance

Leanza

Ferraro

Reichard

et al. 2008

Journal of Biological Chemistry

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Mitochondrial deoxynucleoside triphosphates are formed and regulated by a network of anabolic and catabolic enzymes present both in mitochondria and the cytosol. Genetic deficiencies for enzymes of the network cause mitochondrial DNA depletion and disease. We investigate by isotope flow experiments the interrelation between mitochondrial and cytosolic deoxynucleotide pools as well as the contributions of the individual enzymes of the network to their maintenance. To study specifically the synthesis of dGTP used for the synthesis of mitochondrial and nuclear DNA, we labeled hamster CHO cells or human fibroblasts with [ 3 H]deoxyguanosine during growth and quiescence and after inhibition with aphidicolin or hydroxyurea. At time intervals we determined the labeling of deoxyguanosine nucleotides and DNA and the turnover of dGTP from its specific radioactivity in the separated mitochondrial and cytosolic pools. In both cycling and quiescent cells, the import of deoxynucleotides formed by cytosolic ribonucleotide reductase accounted for most of the synthesis of mitochondrial dGTP, with minor contributions by cytosolic deoxycytidine kinase and mitochondrial deoxyguanosine kinase. A dynamic isotopic equilibrium arose rapidly from the shuttling of deoxynucleotides between mitochondria and cytosol, incorporation of dGTP into DNA, and degradation of dGMP. Inhibition of DNA synthesis by aphidicolin marginally affected the equilibrium. Inhibition of DNA synthesis by blockage of ribonucleotide reduction with hydroxyurea instead disturbed the equilibrium and led to accumulation of labeled dGTP in the cytosol. The turnover of dGTP decreased, suggesting a close connection between ribonucleotide reduction and pool degradation. Mitochondrial (mt)2 deoxynucleotides are formed and regulated by a network of anabolic and catabolic enzymes located in both the cytosol and mitochondria. The enzymes are of considerable medical interest. Many drugs used in cancer and virus therapy are deoxynucleoside analogs whose activity requires phosphorylation by kinases (1) and whose efficacy and toxicity is affected by the interplay between the enzymes in the network. The enzymes may also be involved in oxidative damage by activating modified bases such as 8-oxoguanine for incorporation into RNA and DNA (2). Moreover, an increasing number of diseases with depletion of mt DNA arise from genetic deficiency of enzymes in the network (3). In some cases the genetic deficiency leads to depletion of mt deoxyribonucleoside triphosphate (dNTP) (4 -6), in other cases to overproduction (7-9). In both instances the disturbed normal balance between the four dNTPs results in disease. Early examples are the catabolic phosphorylases that degrade purine (7) or thymine nucleosides (9). Their loss causes overproduction of dGTP or dTTP, with the affected individuals suffering from immune deficiency (7,8) or mitochondrial neurogastrointestinal encephalomyopathy (9), respectively. Later discovered examples are the anabolic mt salvage enzymes deoxyguanosine kinase (dGK) (4...

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Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Metabolic Interrelations within Guanine Deoxynucleotide Pools for Mitochondrial and Nuclear DNA Maintenance

Leanza

Ferraro

Reichard

et al. 2008

Journal of Biological Chemistry

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“…It has been suggested that the combination of nucleoside analogues with gold(I) might be beneficial in eliminating resistance and delayed toxicity [15,16]. An azole -platinum compound displaying in vitro anticancer activity comparable to that of cisplatin is only slightly more active against cisplatin-resistant cancer cells [17].…”

Section: Introductionmentioning

confidence: 99%

Amides of gold(I) diphosphines prepared from N-heterocyclic sources and their in vitro and in vivo screening for anticancer activity

Horvath

Dobrzańska

Strasser

et al. 2012

Journal of Inorganic Biochemistry

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Synopsis __________________________________________________________________________Among a new series of gold(I) complexes that contain diphosphine and deprotonated N-heterocyclic ring systems as ligands, the compounds containing diphenyl(phosphino)pentane and pyrazolate (lypophilic) or 1,2,4,-triazolate (hydrophilic) have high anti-tumour specificities. They induce an apoptic cell death pathway and have the maximum tolerated dose of 1.5 μmol/kg when administered to Balb/C mice. ___________________________________________________________________ *Synopsis for the Graphical abstract  In 25 new complexes diphosphines and azolate-type ligands coordinate to gold  Solvent molecules and counterions appear within channels of a crystalline complex  Cytotoxicity is dependent upon aliphatic C chain length in the ligands  An apoptosis cell death with certain mitochondrial involvement is indicated  Tolerated doses compared to [Au(dppe) 2 ]Cl, tumour specificity is much better *Highlights A B S T R A C T ------------------------------------------------------------------------A series of new neutral mononuclear or dinuclear gold(I) complexes and a cyclic cationic tetranuclear amidogold(I) complex comprising of the phosphines 1,2-bis(dimethylphosphino)ethane (dmpe), μ-1,2-bis(diphenylphosphino)ethane (dppe), μ-1,3-bis(diphenylphosphino)propane (dppp), μ-1,5-bis(diphenylphosphino)pentane (dpppe), μ-1,6-bis(diphenylphosphino)hexane (dpph) or trimethylphosphine, and several N-heterocyclic ring systems (imidazolate, pyrazolate, 1,2,3-triazolate, 1,2,4-triazolate, pyrrolate, 9H-purine-9-ate or 9H-purine-6-amine-9-ate) as ligands, reveal intermolecular aurophilic interactions and 2D channels available for solvent molecules in some of their crystal structures. The antitumou r 2 activity of the acyclic gold(I) compounds is highly dependent on the substituents on the phosphorus atoms being highest for phenyl groups and lower for methyl groups. The activity of these compounds against selected cell lines is linked to the length of the carbon bridge between the two phosphorus atoms being highest with a bridge consisting of 5 or 6 carbons. Two compounds with the highest tumour specifities that contain dpppe and pyrazolate (a lipophilic compound) or 1,2,4-triazolate (a hydrophilic compound) induce the apoptic cell death pathway and tolerate a maximum dose of 1.5 μmol/kg when administered to Balb/C mice.

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“…It was not very surprising that nelarabine and fludarabine showed unaltered sensitivity in the cells since nelarabine is also efficiently activated by the mithochondrial enzyme deoxyguanosine kinase (Zhu et al 2000) and that resistance mechanismsm against fludarabine has been shown to include altered activity of the ribonucleotide reductase enzyme rather than decreased dCK activity (Mansson et al 2003). During these experimental conditions both deoxyguanosine kinase and the ribonucleotide enzyme seemed unaffected by the dCK downregulation, which probably is one of the reasons for the sustained cytotoxicity of nelarabine and fludarabine.…”

Section: Discussionmentioning

confidence: 93%

Optimization and evaluation of electroporation delivery of siRNA in the human leukemic CEM cell line

Fyrberg

Lotfi

2010

Cytotechnology

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In order to study nucleoside analog activation in the CEM cell line, a transfection protocol had to be optimized in order to silence an enzyme involved in nucleoside analog activation. Hematopoetic cell lines can be difficult to transfect with traditional lipid-based transfection, so the electroporation technique was used. Field strength, pulse length, temperature, electroporation media, siRNA concentration, among other conditions were tested in order to obtain approximately 70-80% mRNA and enzyme activity downregulation of the cytosolic enzyme deoxycytidine kinase (dCK), necessary for nucleoside analog activation. Downregulation was assessed at mRNA and enzyme activity levels. After optimizing the protocol, a microarray analysis was performed in order to investigate whether the downregulation was specific. Additionally two genes were differentially expressed besides the downregulation of dCK. These were however of unknown function. The leakage of intracellular nucleotides was also addressed in the electroporated cells since it can affect the DNA repair mechansism and the efficiency of nucleoside analogs. Three of these pools were increased compared to untreated, unelectroporated cells. The siRNA transfected cells with reduced dCK expression and activity showed reduced sensitivity to several nucleoside analogs as expected. The multidrug resistance to other drugs, as seen in nucleoside analog-induced resistant cells, was not seen with this model.

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Differential incorporation of 1‐β‐D‐arabinofuranosylcytosine and 9‐β‐D‐arabinofuranosylguanine into nuclear and mitochondrial DNA

Cited by 17 publications

References 18 publications

Metabolic Interrelations within Guanine Deoxynucleotide Pools for Mitochondrial and Nuclear DNA Maintenance

Metabolic Interrelations within Guanine Deoxynucleotide Pools for Mitochondrial and Nuclear DNA Maintenance

Amides of gold(I) diphosphines prepared from N-heterocyclic sources and their in vitro and in vivo screening for anticancer activity

Optimization and evaluation of electroporation delivery of siRNA in the human leukemic CEM cell line

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