Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.5.1.2 (DNA ligase)
 2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Current evidence suggest an important role for increased repair of drug-induced DNA damage as one of the major mechanisms involved in tumor cell resistance to cis-DDP. In this study, we examined the DNA repair capacity and the activities of three DNA repair related proteins, namely, DNA polymerases alpha and beta, and total DNA ligase in cells of a malignant oligodendroglioma obtained from a patient before therapy and compared it with those of a specimen of the tumor acquired after the patient had failed cis-DDP therapy. DNA repair capacity was quantitated as the extent of reactivation of the chloramphenicol-O-acetyltransferase (CAT) gene in a eukaryotic expression vector that had been damaged and inactivated by prior treatment with cis-DDP and then transfected into the tumor cells. The extent of DNA-platinum adduct formation in the expression vector was determined by flameless atomic absorption spectrometry. The level of cis-DDP resistance of cells of the two tumors was determined with the capillary tumor stem cell assay. We observed a 2.8-fold increased capacity to repair Pt-DNA adducts and reactivate the CAT gene in cells of the tumor obtained after cis-DDP therapy, compared to cells of the untreated tumor. This was associated with increases of 9.4-fold and a 2.3-fold, respectively, in DNA polymerase beta and total DNA ligase activities in cells of the treated tumor. At 5 microM cis-DDP, there was a 5.9-fold increase in the in vitro cis-DDP resistance of post-therapy tumor cells relative to cells of the untreated tumor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enhanced repair of a cisplatin-damaged reporter chloramphenicol-O-acetyltransferase gene and altered activities of DNA polymerases alpha and beta, and DNA ligase in cells of a human malignant glioma following in vivo cisplatin therapy. 812 81

In rat cultured pulmonary arterial (PA), microvascular, and venous endothelial cells (ECs), the rate of mitochondrial (mt) DNA repair is predictive of the severity of xanthine oxidase (XO)-induced mtDNA damage and the sensitivity to XO-mediated cell death. To examine the importance of mtDNA damage and repair more directly, we determined the impact of mitochondrial overexpression of the DNA repair enzyme, Ogg1, on XO-induced mtDNA damage and cell death in PAECs. PAECs were transiently transfected with an Ogg1-mitochondrial targeting sequence construct. Mitochondria-selective overexpression of the transgene product was confirmed microscopically by the observation that immunoreactive Ogg1 colocalized with a mitochondria-specific tracer and, with an oligonucleotide cleavage assay, by a selective enhancement of mitochondrial Ogg1 activity. Overexpression of Ogg1 protected against both XO-induced mtDNA damage, determined by quantitative Southern analysis, and cell death as assessed by trypan blue exclusion and MTS assays. These findings show that mtDNA damage is a direct cause of cell death in XO-treated PAECs.
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PMID:Enhanced mtDNA repair capacity protects pulmonary artery endothelial cells from oxidant-mediated death. 1206 May 78

Recent evidence has linked mitochondrial dysfunction and DNA damage, increased oxidative stress in skeletal muscle, and insulin resistance (IR). The purpose of this study was to determine the role of the DNA repair enzyme, human 8-oxoguanine DNA glycosylase/apurinic/apyrimidinic lyase (hOGG1), on palmitate-induced mitochondrial dysfunction and IR in primary cultures of skeletal muscle derived from hind limb of ogg1(-/-) knockout mice and transgenic mice, which overexpress human (hOGG1) in mitochondria (transgenic [Tg]/MTS-hOGG1). Following exposure to palmitate, we evaluated mitochondrial DNA (mtDNA) damage, mitochondrial function, production of mitochondrial reactive oxygen species (mtROS), mitochondrial mass, JNK activation, insulin signaling pathways, and glucose uptake. Palmitate-induced mtDNA damage, mtROS, mitochondrial dysfunction, and activation of JNK were all diminished, whereas ATP levels, mitochondrial mass, insulin-stimulated phosphorylation of Akt (Ser 473), and insulin sensitivity were increased in primary myotubes isolated from Tg/MTS-hOGG1 mice compared to myotubes isolated from either knockout or wild-type mice. In addition, both basal and maximal respiratory rates during mitochondrial oxidation on pyruvate showed a variable response, with some animals displaying an increased respiration in muscle fibers isolated from the transgenic mice. Our results support the model that DNA repair enzyme OGG1 plays a pivotal role in repairing mtDNA damage, and consequently, in mtROS production and regulating downstream events leading to IR in skeletal muscle.
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PMID:Alteration of mitochondrial function and insulin sensitivity in primary mouse skeletal muscle cells isolated from transgenic and knockout mice: role of ogg1. 2374 60

The nephrotoxicity of cisplatin (cis-DDP) limits its general clinical applications. Lentinan (LNT), a dextran extracted from the mushroom Lentinula edodes, has been shown to have multiple pharmacological activities. The primary objective of the current study was to determine whether and how LNT alleviates cis-DDP- induced cytotoxicity in HK-2 cells and nephrotoxicity in mice. LNT did not interfere with cisplatin's anti-tumour efficacy in vitro and functioned cooperatively with cis-DDP to inhibit activity in HeLa and A549 tumour cells. LNT alleviated the cis-DDP-induced decrease in HK-2 cell viability, caspase-3 activation and cleavage of the DNA repair enzyme PARP, decreased HK-2 cell apoptosis and inhibited reactive oxygen species (ROS) accumulation in HK-2 cells. The inhibitor of ROS (N-acetyl-L-cysteine, NAC) could decreased the apoptosis of HK-2 cell. In addition, LNT significantly prevented cis-DDP-induced kidney injury in vivo. LNT itself could not eliminate ROS levels in vitro. Further studies demonstrated that LNT induced NF-E2 p45-related factor 2 (Nrf2) protein and mRNA expression in a time- and dose-dependent manner. LNT promoted Nrf2 translocation to the nucleus and binding to the antioxidant-response element (ARE) sequence and induced the transcription and translation of heme oxygenase 1 (HO-1), aldo-keto reductases 1C1 and 1C2 (AKR1C), and NADP(H):quinone oxidoreductase 1 (NQO1). Finally, we used hNrf2 siRNA and an Nrf2 agonist (tBHQ) to inhibit or enhance Nrf2 expression. The results demonstrated that the LNT-mediated alleviation of cis-DDP-induced nephrotoxicity was achieved by preventing the accumulation of ROS in a manner that depended on the activation of the Nrf2-ARE signalling pathway.
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PMID:Activation of the NRF2-ARE signalling pathway by the Lentinula edodes polysaccharose LNT alleviates ROS-mediated cisplatin nephrotoxicity. 2709 15