Changes in expression profiles of antioxidant enzymes in diabetic rat kidneys.

BACKGROUND: In diabetes mellitus, increased formation of reactive oxygen species due to high level of glucose in both blood plasma and tissues creates oxidative stress and damages the tissues. Antioxidants together with the antioxidant enzymes are very important in order to protect the cells against oxidative damage. METHODS: Differential expressions of both mRNA and proteins of major antioxidant enzymes in streptozotocin-induced diabetic rat kidneys were measured with the help of real-time polymerase chain reaction and western blot analysis, respectively. Furthermore, effects of two strong antioxidants α-lipoic acid, vitamin C and their combination on the regulation of both expressions and the activities of antioxidant enzymes were also studied. RESULTS: In diabetic rat kidney tissue, both catalase and glutathione peroxidase activities were reduced (although mRNA expression for both was greatly increased) when compared with controls. No significant change was observed in superoxide dismutase (SOD) activity. Alpha-lipoic acid increased catalase activity towards the control values. Combined administration of alpha-lipoic acid and vitamin C increased the activities of both catalase and SOD, demonstrating a posttranslational effect. Glutathione concentrations were decreased in diabetic kidney; alpha-lipoic acid treatment partially restored the glutathione levels. CONCLUSIONS: All data showed the importance of post-transcriptional and translational regulation of the antioxidant enzyme activities against oxidative stress that is associated with diabetes.

Gene expressions of Mn-SOD and GPx-1 in streptozotocin-induced diabetes: effect of antioxidants.

Increased oxidative stress and impaired antioxidant defense mechanisms are believed to be the important factors contributing to the pathogenesis and progression of diabetes mellitus. In this study, we have reported the effects of the streptozotocin-induced diabetes on the gene expression and the activities of two antioxidant enzymes, manganese superoxide dismutase (MnSOD) and glutathione peroxidase (GPx). We also studied the effects of two antioxidants, vitamin C and DL-alpha-lipoic acid (LA), on the system. Our results showed no significant change in both enzymes activities in diabetic animals compared to controls. Similarly, mRNA and protein profiles of MnSOD showed no change. Though the mRNA expression of GPx did not show any change, Western-blot analysis results demonstrated that protein expression is increased. LA, which is a water- and lipid-soluble antioxidant, decreased the protein expression of MnSOD, though mRNA levels and activities remained unchanged. LA treatment increased the GPx activities in diabetic tissues, significantly, and RT-PCR and Western-blot analysis results demonstrated that this increase in activity is not regulated at the gene level, as both mRNA and protein levels did not change. Supplementing the animals with vitamin C, a powerful water-soluble antioxidant, increased the mRNA expression of MnSOD, though the protein expression and the activity did not change statistically. On the other hand GPx activity increased significantly through post-translational modifications, as both mRNA and protein expressions did not change. These results together with our previous findings about the gene expressions of catalase and Cu-Zn SOD indicate the presence of very intricate control mechanisms regulating the activities of antioxidant enzymes in order to prevent the damaging effects of oxidative stress.

Differential expressions and functions of phosphodiesterase enzymes in different regions of the rat heart.

Phosphodiesterase enzymes (PDEs) are responsible for the adjustment of cyclic nucleotide levels. Alterations in PDE expressions in different tissues cause conflicts between functional and clinical effects of PDE inhibitors. Therefore, the aim of this study was to investigate the gene and protein expressions and the functional role of PDEs in atrium and ventricle of rat heart. The expressions of PDEs were examined in cardiac intact tissues and enzymatically isolated cells. The effects of PDE1-5 inhibitors (vinpocetine, EHNA, milrinone, rolipram, sildenafil, and IBMX) on basal and isoprenaline-stimulated contractions and sinus rate were recorded in the isolated spontaneously beating right atrium and electrically stimulated left papillary muscles. The mRNA and protein levels of PDEs were significantly different in atrial and ventricular intact tissues and isolated myocytes. Atrial contractions were increased with vinpocetine while suppressed by EHNA, milrinone, rolipram, sildenafil and IBMX. Milrinone, sildenafil and IBMX increased the heart rate whereas vinpocetine caused negative chronotropy. Papillary muscle contractions have been increased only with the vinpocetine and IBMX. Both the expression and the action of PDE-1-5 show atrial and ventricular differences. Therefore, these differences should be taken into account in the experimental or therapeutic approaches of the heart.

EF2-kinase targeted cobalt-ferrite siRNA-nanotherapy suppresses BRCA1-mutated breast cancer.

Aim: To investigate the role of EF2K in BRCA1-mutated breast cancer. Materials & methods: We developed silica coated cobalt-ferrite (CoFe) nanoparticles for in vivo delivery of small interfering RNAs (siRNAs) into BRCA1-mutated breast cancer. Results: Expression of EF2K is highly upregulated in the majority (78.5%) of BRCA1-mutated patients and significantly associated with poor patient survival and metastasis. Silencing of EF2K reduced cell proliferation, migration and invasion of the cancer cells. In vivo therapeutic targeting of EF2K by CoFe-siRNA-nanoparticles leads to sustained EF2K gene knockdown and suppressed tumor growth in orthotopic xenograft models of BRCA1-mutated breast cancer. Conclusion: EF2K is a potential novel molecular target in BRCA1-mutated tumors and CoFe-based siRNA nanotherapy may be used as a novel approach to target EF2K.

Effect of vitamin C and lipoic acid on streptozotocin-induced diabetes gene expression: mRNA and protein expressions of Cu-Zn SOD and catalase.

The involvement of oxidative stress in the pathogenesis of diabetes mellitus has been confirmed by numerous studies. In this study, the expression of two antioxidant enzymes, superoxide dismutase (SOD), and catalase which are involved in the detoxification of reactive oxygen species was studied in the streptozotocin-induced diabetic rat liver tissues. The enzyme assays showed a significant decrease in both enzymes activities compared to control animals. The RT-PCR and Western-blot analysis results demonstrated that this decrease in activity is regulated at the level of gene expression, as both catalase and Cu-Zn SOD mRNA and protein expressions were also suppressed. Supplementing the animals with vitamin C, a powerful antioxidant increased both SOD and catalase activities with no change in both mRNA and protein expressions suggesting a role of post-translational modification. However, even though mRNA expressions of both catalase and Cu-Zn SOD were not changed, the protein levels increased in parallel to activities in the case of another antioxidant, alpha-lipoic acid. An increase in the rate of translation, without changing the rate of transcription indicates a translational effect of lipoic acid in changing the activities of antioxidant enzymes to prevent the oxidative damage in diabetes.

Rapid monitoring of diabetes-induced lipid peroxidation by Fourier transform infrared spectroscopy: evidence from rat liver microsomal membranes.

Increased oxidative stress is the consequence of either enhanced reactive oxygen species (ROS) production or attenuated ROS scavenging capacity, resulting in tissue damage that in most instances is assessed by the measurement of lipid peroxides. In the current study, diabetes-induced lipid peroxidation in rat liver microsomal membranes was investigated by Fourier transform infrared (FT-IR) spectroscopy at different temperatures. The olefinic (CH) band at 3012 cm-1 was used to probe diabetes-induced lipid peroxidation. The intensity and area values of this band of diabetic samples were found to be increased significantly (P<0.05) compared with nondiabetic samples. The increase in olefinic band intensity is attributed mainly to the lipid peroxidation end products. The results of the FT-IR study were found to be in agreement with biochemical studies that revealed a significant increase in malondialdehyde levels of diabetic samples compared with control samples (P<0.05) using the thiobarbituric acid test.