Depletion of mitochondrial DNA by down-regulation of deoxyguanosine kinase expression in non-proliferating HeLa cells

ABSTRACTMitochondrial thymidine kinase 2 (TK2) and deoxyguanosine kinase (dGK) catalyze the initial phosphorylation of deoxynucleosides in the synthesis of the DNA precursors required for mitochondrial DNA (mtDNA) replication and are essential for mitochondrial function. Antiviral nucleosides are known to cause toxic mitochondrial side effects. Here, we examined the effects of 3′-azido-2′,3′-dideoxythymidine (AZT) (zidovudine) on mitochondrial TK2 and dGK levels and found that AZT treatment led to downregulation of mitochondrial TK2 and dGK in U2OS cells, whereas cytosolic deoxycytidine kinase (dCK) and thymidine kinase 1 (TK1) levels were not affected. The AZT effects on mitochondrial TK2 and dGK were similar to those of oxidants (e.g., hydrogen peroxide); therefore, we examined the oxidative effects of AZT. We found a modest increase in cellular reactive oxygen species (ROS) levels in the AZT-treated cells. The addition of uridine to AZT-treated cells reduced ROS levels and protein oxidation and prevented the degradation of mitochondrial TK2 and dGK.In organellostudies indicated that the degradation of mitochondrial TK2 and dGK is a mitochondrial event. These results suggest that downregulation of mitochondrial TK2 and dGK may lead to decreased mitochondrial DNA precursor pools and eventually mtDNA depletion, which has significant implications for the regulation of mitochondrial nucleotide biosynthesis and for antiviral therapy using nucleoside analogs.

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A fatal case of mitochondrial DNA depletion syndrome with novel compound heterozygous variants in the deoxyguanosine kinase gene

Oncotarget ◽

10.18632/oncotarget.20905 ◽

2017 ◽

Vol 8 (48) ◽

pp. 84309-84319 ◽

Cited By ~ 3

Author(s):

Weiyuan Fang ◽

Peng Song ◽

Xinbao Xie ◽

Jianshe Wang ◽

Yi Lu ◽

...

Keyword(s):

Mitochondrial Dna ◽

Fatal Case ◽

Compound Heterozygous ◽

Kinase Gene ◽

Mitochondrial Dna Depletion ◽

Deoxyguanosine Kinase ◽

Compound Heterozygous Variants ◽

Mitochondrial Dna Depletion Syndrome

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A novel mutation in the deoxyguanosine kinase gene causing depletion of mitochondrial DNA

Annals of Neurology ◽

10.1002/ana.10247 ◽

2002 ◽

Vol 52 (2) ◽

pp. 237-239 ◽

Cited By ~ 29

Author(s):

Jan-Willem Taanman ◽

Ihab Kateeb ◽

Ania C. Muntau ◽

Michaela Jaksch ◽

Nadine Cohen ◽

...

Keyword(s):

Mitochondrial Dna ◽

Novel Mutation ◽

Kinase Gene ◽

Deoxyguanosine Kinase

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Mitochondrial DNA depletion can be prevented by dGMP and dAMP supplementation in a resting culture of deoxyguanosine kinase-deficient fibroblasts

Human Molecular Genetics ◽

10.1093/hmg/ddg192 ◽

2003 ◽

Vol 12 (15) ◽

pp. 1839-1845 ◽

Cited By ~ 63

Author(s):

J.-W. Taanman ◽

J. R. Muddle ◽

A. C. Muntau

Keyword(s):

Mitochondrial Dna ◽

Mitochondrial Dna Depletion ◽

Deoxyguanosine Kinase

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Viscum albumL. Extracts Protects HeLa Cells against Nuclear and Mitochondrial DNA Damage

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2012/958740 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Evren Önay-Uçar ◽

Özlem Erol ◽

Başak Kandemir ◽

Elif Mertoğlu ◽

Ali Karagöz ◽

...

Keyword(s):

Dna Damage ◽

Mitochondrial Dna ◽

Hela Cells ◽

Oxidative Dna Damage ◽

Nuclear Dna ◽

Viscum Album ◽

Mitochondrial Dna Damage ◽

Methanolic Extracts ◽

Host Trees ◽

Lime Tree

Viscum albumL. is a semiparasitic plant grown on trees and widely used for the treatment of many diseases in traditional and complementary therapy. It is well known that some activities ofViscum albumextracts are varied depending on the host trees, such as antioxidant, apoptosis-inducing, anticancer activities of the plant. The aim of the present study is to examine the comparative effects of methanolic extracts ofV. albumgrown on three different host trees (locust tree, lime tree, and hedge maple tree) on H2O2-induced DNA damage in HeLa cells. Oxidative damage in mitochondrial DNA and two nuclear regions was assessed by QPCR assay. The cells were pretreated with methanolic extracts (10 μg/mL) for 48 h, followed by the treatment with 750 μM H2O2for 1 hour. DNA damage was significantly induced by H2O2while it was inhibited byV. albumextracts. All extracts completely protected against nuclear DNA damage. While the extract from lime tree or white locust tree entirely inhibited mitochondrial DNA damage, that from hedge maple tree inhibited by only 50%. These results suggest that methanolic extracts ofV. albumcan prevent oxidative DNA damage, and the activity is dependent on the host tree.

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