Conditional Targeting of the DNA Repair Enzyme hOGG1 into Mitochondria

Rachek, Lyudmila I.; Grishko, Valentina; Musiyenko, Sergiy I.; Kelley, Mark R.; LeDoux, Susan P.; Wilson, Glenn L.

doi:10.1074/jbc.m208770200

Cited by 91 publications

(70 citation statements)

References 41 publications

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“…Although BER in the mitochondria repairs normal endogenous oxidant-induced DNA damage, expression of mitochondrially targeted DNA glycosylases that are specific for the repair of oxidatively induced DNA lesions leads to enhanced repair and increased survival after ROS challenge (7)(8)(9)(10). These data emphasize that maintenance of the mitochondrial genome is a delicate balance of mtDNA copy number and BER capacity.…”

mentioning

confidence: 83%

The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase

Vartanian

Lowell

Minko

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

224

221

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Endogenously formed reactive oxygen species continuously damage cellular constituents including DNA. These challenges, coupled with exogenous exposure to agents that generate reactive oxygen species, are both associated with normal aging processes and linked to cardiovascular disease, cancer, cataract formation, and fatty liver disease. Although not all of these diseases have been definitively shown to originate from mutations in nuclear DNA or mitochondrial DNA, repair of oxidized, saturated, and ring-fragmented bases via the base excision repair pathway is known to be critical for maintaining genomic stability. One enzyme that initiates base excision repair of ring-fragmented purines and some saturated pyrimidines is NEIL1, a mammalian homolog to Escherichia coli endonuclease VIII. To investigate the organismal consequences of a deficiency in NEIL1, a knockout mouse model was created. In the absence of exogenous oxidative stress, neil1 knockout (neil1 ؊/؊ ) and heterozygotic (neil1 ؉/؊ ) mice develop severe obesity, dyslipidemia, and fatty liver disease and also have a tendency to develop hyperinsulinemia. In humans, this combination of clinical manifestations, including hypertension, is known as the metabolic syndrome and is estimated to affect >40 million people in the United States. Additionally, mitochondrial DNA from neil1 ؊/؊ mice show increased levels of steady-state DNA damage and deletions relative to wild-type controls. These data suggest an important role for NEIL1 in the prevention of the diseases associated with the metabolic syndrome.DNA repair ͉ fatty liver disease ͉ mitochondria ͉ obesity ͉ oxidative stress A fter exposure to reactive oxygen species (ROS), the major purine lesions are 8-oxoguanine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, and 4,6-diamino-5-formamidopyrimidine (1-5). To reverse the potentially deleterious effects of oxidative DNA base lesions, cells primarily use the base excision repair (BER) pathway to restore the DNA to its undamaged state (6). The BER pathway is initiated by lesion-specific DNA glycosylases that catalyze bond scission and release the damaged base from the deoxyribose sugar.Unlike nucleotide excision repair, which functions only on nuclear DNA, the BER pathway is operative on both nuclear DNA and mitochondrial DNA (mtDNA). Although BER in the mitochondria repairs normal endogenous oxidant-induced DNA damage, expression of mitochondrially targeted DNA glycosylases that are specific for the repair of oxidatively induced DNA lesions leads to enhanced repair and increased survival after ROS challenge (7-10). These data emphasize that maintenance of the mitochondrial genome is a delicate balance of mtDNA copy number and BER capacity.To initiate repair of oxidative lesions, mammalian cells primarily use the products of the ogg1, nth1, neil1, and neil2 genes (11). These corresponding proteins have somewhat overlapping substrate specificities that may explain, at least partially, the absence of obvious phenotypes in ogg1-and nth1-null mice. NEIL1 has a strong sub...

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confidence: 83%

The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase

Vartanian

Lowell

Minko

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

224

221

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“…OGG1 has been shown to have both nuclear and mitochondrial localization. Several cell culture studies have addressed the role of mitochondrial OGG1 on diverse cellular functions, including insulin secretion from INS-1 cells and glucose uptake in C2C12 cells [Rachek et al, 2002;Rachek et al, 2006;Yuzefovych et al, 2012]. Some of the findings from these cell studies have been replicated in a recently developed transgenic mouse model overexpressing a mitochondrial form of human OGG1 [Yuzefovych et al, 2012]; this model is discussed in greater detail below.…”

Section: Ogg1mentioning

confidence: 99%

Oxidative DNA damage in disease—Insights gained from base excision repair glycosylase‐deficient mouse models

Sampath

2014

Environ and Mol Mutagen

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Cellular components, including nucleic acids, are subject to oxidative damage. If left unrepaired, this damage can lead to multiple adverse cellular outcomes, including increased mutagenesis and cell death. The major pathway for repair of oxidative base lesions is the base excision repair pathway, catalyzed by DNA glycosylases with overlapping but distinct substrate specificities. To understand the role of these glycosylases in the initiation and progression of disease, several transgenic mouse models have been generated to carry a targeted deletion or overexpression of one or more glycosylases. This review summarizes some of the major findings from transgenic animal models of altered DNA glycosylase expression, especially as they relate to pathologies ranging from metabolic disease and cancer to inflammation and neuronal health. Environ. Mol. Mutagen. 55:689-703, 2014. V C 2014 Wiley Periodicals, Inc.

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“…MTS-OGG1-and vector-onlytransfected cells were exposed to FFAs as described above. DNA isolation and quantitative Southern blots were performed as previously described (18,19). Briefly, cells were lysed in 10 mmol/l Tris-HCl (pH 8.0), 1 mmol/l EDTA (pH 8.0), 0.5% SDS, and 0.3 mg/ml proteinase K overnight at 37°C.…”

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confidence: 99%

“…A sodium hydroxide solution was then added to a final concentration of 0.1 N, and samples were incubated for 15 min at 37°C. Gel electrophoresis and vacuum transfer were carried out as described previously (18,19). Membranes were hybridized with a denatured PCR-generated mitochondrial probe (9,20), washed, and autoradiographed.…”

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confidence: 99%

Protection of INS-1 Cells From Free Fatty Acid–Induced Apoptosis by Targeting hOGG1 to Mitochondria

et al. 2006

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Chronic exposure to elevated levels of free fatty acids (FFAs) impairs pancreatic ␤-cell function and contributes to the decline of insulin secretion in type 2 diabetes. Previously, we reported that FFAs caused increased nitric oxide (NO) production, which damaged mitochondrial DNA (mtDNA) and ultimately led to apoptosis in INS-1 cells. To firmly establish the link between FFA-generated mtDNA damage and apoptosis, we stably transfected INS-1 cells with an expression vector containing the gene for the DNA repair enzyme human 8-oxoguanine DNA glycosylase/ apurinic lyase (hOGG1) downstream of the mitochondrial targeting sequence (MTS) from manganese superoxide dismutase. Successful integration of MTS-OGG1 into the INS-1 cellular genome was confirmed by Southern blot analysis. Western blots and enzyme activity assays revealed that hOGG1 was targeted to mitochondria and the recombinant enzyme was active. MTS-OGG1 cells showed a significant decrease in FFA-induced mtDNA damage compared with vector-only transfectants. Additionally, hOGG1 overexpression in mitochondria decreased FFA-induced inhibition of ATP production and protected INS-1 cells from apoptosis. These results indicate that mtDNA damage plays a pivotal role in FFA-induced ␤-cell dysfunction and apoptosis. Therefore, targeting DNA repair enzymes into ␤-cell mitochondria could be a potential therapeutic strategy for preventing or delaying the onset of type 2 diabetes symptoms. Diabetes 55:1022-1028, 2006 C hronic elevation of cellular free fatty acids (FFAs) is associated with both insulin resistance and type 2 diabetes (1,2). Results obtained from a variety of different laboratories suggest that the accumulation of lipid into islet tissue is deleterious to normal ␤-cell function and that this elevation in FFA content ultimately leads to ␤-cell failure and death through a process termed "lipotoxicity." Exposure of ␤-cells to high concentrations of FFAs has been correlated with impaired insulin secretion and changes in the expression of genes involved in the lipogenic and fat oxidation pathways and is considered to be an important factor in the pathogenesis of type 2 diabetes (3,4). Moreover, FFAs have been shown to cause ␤-cell death by both apoptotic and necrotic mechanisms (5,6). Although the exact mechanisms involved in FFA-induced apoptosis and necrosis remain to be clarified, it has been suggested that the ␤-cell dysfunction and death observed in type 2 diabetes may involve exaggerated activation of the inducible form of nitric oxide synthase (iNOS) by FFAs with the consequent generation of excess nitric oxide (NO) (7).Although NO plays a prominent role in regulating many biological functions, a growing body of evidence indicates that at high concentrations, it can also be cytotoxic and mutagenic (8). However, the cellular targets with which NO interacts have not been fully identified. We hypothesized that one of these targets might be mitochondrial DNA (mtDNA). Recently, we reported that FFAs (2:1, oleate:palmitate) caused a rise in NO production that ...

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Conditional Targeting of the DNA Repair Enzyme hOGG1 into Mitochondria

Cited by 91 publications

References 41 publications

The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase

The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase

Oxidative DNA damage in disease—Insights gained from base excision repair glycosylase‐deficient mouse models

Protection of INS-1 Cells From Free Fatty Acid–Induced Apoptosis by Targeting hOGG1 to Mitochondria

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