d-arg-dmt-lys-phe-nh2 and 3-nitrotyrosine

The present study aimed to investigate the ability of SS31, a novel mitochondria‑targeted peptide to protect against t‑BHP‑induced mitochondrial dysfunction and apoptosis in 661W cell lines. The 661W cells were treated with various concentrations of SS‑31 and an MTT assay was used to determine cell viability. The expression of nitrotyrosine and 8‑hydroxydeoxyguanosine (8‑OHdG) was detected using immunofluorescent staining. Apoptosis were assessed using Hoechst staining and an annexin V/propidium iodide flow cytometer. Reactive oxygen species (ROS) were detected using MitoSOXTM with confocal microscopy. Changes in mitochondrial membrane potential were analyzed using flow cytometry. In addition, the release of cytochrome c was analyzed using confocal microscopy. The viability of the cells improved following treatment with SS31 between 100 nM and 1 µM, compared with untreated control group. Compared with the t‑BHP treatment group (20.0±3.8%), the number of annexin V‑positive cells decreased dose‑dependently to 13.6±2.6, 9.8±0.5 and 7.4±2.0% in the SS‑31 treated group at concentrations of 10 nM, 100 nM and 1 µM, respectively. Treatment with SS‑31 significantly prevented the t‑BHP‑induced expression of nitrotyrosine and 8‑OHdG, decreased the quantity of mitochondrial ROS, increased mitochondrial potential, and prevented the release of cytochrome c from mitochondria into the cytoplasm. Therefore, the SS31 mitochondria‑targeted peptide protected the 661W cells from the sustained oxidative stress induced by t‑BHP.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Apoptosis; Cell Line, Transformed; Cell Survival; Cytochromes c; Deoxyguanosine; Membrane Potential, Mitochondrial; Mice; Mitochondria; Oligopeptides; Oxidants; Oxidative Stress; Reactive Oxygen Species; Retinal Cone Photoreceptor Cells; tert-Butylhydroperoxide; Tyrosine

Oxidative stress is one of the main contributors in the pathogenesis of diabetic retinopathy. The aim of this study is to investigate the effects of SS31 which is a mitochondria-targeted antioxidant peptide on the retinas of streptozotocin (STZ)-induced diabetic rats. Two weeks after induction of diabetes, SS31 (3 mg/kg) or the same volume of normal saline (N.S) was injected subcutaneously into the back of diabetic rats every day. Four months later, the integrity of inner blood retinal barrier (iBRB) was measured by Evans blue perfusion. The expression and distribution of claudin-5, occludin, acrolein, 8-OHdG and nitrotyrosine in the rat retinas were detected by immunofluorescent staining. Retinal ultrastructures were observed by transmission electron microscopy. The protein level of VEGFR2, Trx-2, Bcl-2, Bax, caspase-3, p53, and NF-κB in the rat retinas were assayed by western blot. Four months after subcutaneous injection, the diabetic rats treated with SS31 had better structures of retinal ganglion cells, thinner capillary basement membrane, less iBRB leakage, more uniform staining of claudin-5 and occludin in the retinal vessels, lower levels of acrolein, 8-OHdG, nitrotyrosine, Bax, caspase-3, p53, and NF-κB, and higher levels of Trx-2 and Bcl-2 in the retinas than those treated with N.S. In conclusion, SS31 could protect the retinal structures and inhibit the breakdown of iBRB by reducing oxidative damage, increasing Trx-2 and Bcl-2 expression, and decreasing p53, NF-κB, Bax, caspase-3, and VEGFR2 expression in the retinas of diabetic rats. SS31 could be a potential new treatment for diabetic retinopathy and other oxidative stress-related diseases.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acrolein; Animals; Antioxidants; Blood Glucose; Blood-Retinal Barrier; Body Weight; Capillaries; Claudin-5; Deoxyguanosine; Diabetes Mellitus, Experimental; Endoplasmic Reticulum; Male; Mitochondria; Occludin; Oligopeptides; Oxidative Stress; Protective Agents; Protein Transport; Rats; Rats, Sprague-Dawley; Retina; Signal Transduction; Tyrosine; Vascular Endothelial Growth Factor Receptor-2