cytochrome-c-t and 8-oxo-7-8-dihydrodeoxyguanine

The mitochondrial DNA base modification 8-hydroxy 2'-deoxyguanine (8-OHdG) is one of the most common DNA lesions induced by reactive oxygen species (ROS) and is considered an index of DNA damage. High levels of mitochondrial 8-OHdG have been correlated with increased mutation, deletion, and loss of mitochondrial (mt) DNA, as well as apoptosis. 8-Oxoguanosine DNA glycosylase-1 (OGG1) recognizes and removes 8-OHdG to prevent further DNA damage. We evaluated the effects of OGG1 on mtDNA damage, mitochondrial function, and apoptotic events induced by oxidative stress using H9C2 cardiac cells treated with menadione and transduced with either Adv-Ogg1 or Adv-Control (empty vector). The levels of mtDNA 8-OHdG and the presence of apurinic/apyrimidinic (AP) sites were decreased by 30% and 35%, respectively, in Adv-Ogg1 transduced cells (P < 0.0001 and P < 0.005, respectively). In addition, the expression of base excision repair (BER) pathway members APE1 and DNA polymerase γ was upregulated by Adv-Ogg1 transduction. Cells overexpressing Ogg1 had increased membrane potential (P < 0.05) and decreased mitochondrial fragmentation (P < 0.005). The mtDNA content was found to be higher in cells with increased OGG1 (P < 0.005). The protein levels of fission and apoptotic factors such as DRP1, FIS1, cytoplasmic cytochrome c, activated caspase-3, and activated caspase-9 were lower in Adv-Ogg1 transduced cells. These observations suggest that Ogg1 overexpression may be an important mechanism to protect cardiac cells against oxidative stress damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; Cardiotonic Agents; Caspase 3; Caspase 9; Cell Line; Cell Survival; Cytochromes c; DNA Damage; DNA Glycosylases; DNA Polymerase gamma; DNA-(Apurinic or Apyrimidinic Site) Lyase; DNA-Directed DNA Polymerase; DNA, Mitochondrial; Dynamins; Guanine; Heart Failure; Mice; Mitochondria, Heart; Mitochondrial Proteins; Myocardium; Oxidative Stress; Rats; Vitamin K 3

Diabetic peripheral neuropathy (DPN) is one of the most common and costly microvascular complications of diabetes, and no effective therapy exists. Previous studies have demonstrated that oxidative stress may be the unifying factor for the damaging effect of hyperglycemia. The aim of this study was to examine the impact of treatment with Alpha lipoic acid (ALA) on the intermittent high glucose (IHG) or high glucose (HG)-induced oxidative stress-induced mitochondrial pathway activation and Schwann cells (SCs) apoptosis in vitro. Our results suggested that IHG and HG induced SCs apoptosis in both caspase-dependent and caspase-independent pathways related to oxidative stress. More importantly, the cytotoxic effect of IHG was significantly more potent than that of HG. Treatment with ALA inhibited the IHG and HG-induced oxidative stress and apoptosis in SCs. Furthermore, treatment with ALA down-regulated the Bax expression and the release of cytochrome c and AIF translocation, but up-regulated the Bcl-2 expression in SCs. Treatment with ALA attenuated the activation of caspase-3 and caspase-9 and minimized the cleavage of PARP in SCs. These findings suggest that variability in glycemic control could be more deleterious than a constant HG and ALA antagonized the IHG-induced oxidative stress, activation of mitochondrial pathway and apoptosis in SCs.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; Apoptosis Inducing Factor; bcl-2-Associated X Protein; Cell Survival; Cells, Cultured; Cytochromes c; Gene Expression Regulation; Glucose; Guanine; Membrane Potential, Mitochondrial; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Schwann Cells; Sciatic Nerve; Thioctic Acid