Browsing by Author "Vidaković, Melita (6603600629)"

Purpose: The combined hyperglycemia lowering and antioxidant actions of α-lipoic acid (LA) contribute to its usefulness in preventing renal injury and other diabetic complications. The precise mechanisms by which LA alters diabetic oxidative renal injury are not known. We hypothesized that LA through its hypoglycemic effect lowers O-GlcNAcylation which influences the expression and activities of antioxidant enzymes which assume important roles in preventing diabetes-induced oxidative renal injury. Methods: An experimental model of diabetes was induced in rats by the administration of 40 mg/kg streptozotocin (STZ) intraperitoneally (i.p.) for five consecutive days. LA was applied at a dose of 10 mg/kg i.p. for 4 weeks, starting from the last day of STZ administration. Results: An improved glycemic status of LA-treated diabetic rats was accompanied by a significant suppression of oxidative stress and a reduction of oxidative damage of lipids, proteins and DNA. LA treatment normalized CuZn-superoxide dismutase (SOD) and catalase activities in renal tissue of diabetic rats. These changes were allied with upregulated gene expression and lower levels of O-GlcNA glycosylation. The accompanying increase in MnSOD activity was only linked with upregulated gene expression. The observed antioxidant enzyme gene regulation was accompanied by nuclear translocation of Nuclear factor-erythroid-2-related factor 2 (Nrf2), enhanced expression of heat shock proteins (HSPs) and by reduction in O-GlcNAcylation of HSP90, HSP70, and extracellular regulated kinase and p38. Conclusion: α-Lipoic acid administration activates a coordinated cytoprotective response against diabetes-induced oxidative injury in kidney tissue through an O-GlcNAc-dependent mechanism. © 2012 Springer-Verlag Berlin Heidelberg.

Purpose: The combined hyperglycemia lowering and antioxidant actions of α-lipoic acid (LA) contribute to its usefulness in preventing renal injury and other diabetic complications. The precise mechanisms by which LA alters diabetic oxidative renal injury are not known. We hypothesized that LA through its hypoglycemic effect lowers O-GlcNAcylation which influences the expression and activities of antioxidant enzymes which assume important roles in preventing diabetes-induced oxidative renal injury. Methods: An experimental model of diabetes was induced in rats by the administration of 40 mg/kg streptozotocin (STZ) intraperitoneally (i.p.) for five consecutive days. LA was applied at a dose of 10 mg/kg i.p. for 4 weeks, starting from the last day of STZ administration. Results: An improved glycemic status of LA-treated diabetic rats was accompanied by a significant suppression of oxidative stress and a reduction of oxidative damage of lipids, proteins and DNA. LA treatment normalized CuZn-superoxide dismutase (SOD) and catalase activities in renal tissue of diabetic rats. These changes were allied with upregulated gene expression and lower levels of O-GlcNA glycosylation. The accompanying increase in MnSOD activity was only linked with upregulated gene expression. The observed antioxidant enzyme gene regulation was accompanied by nuclear translocation of Nuclear factor-erythroid-2-related factor 2 (Nrf2), enhanced expression of heat shock proteins (HSPs) and by reduction in O-GlcNAcylation of HSP90, HSP70, and extracellular regulated kinase and p38. Conclusion: α-Lipoic acid administration activates a coordinated cytoprotective response against diabetes-induced oxidative injury in kidney tissue through an O-GlcNAc-dependent mechanism. © 2012 Springer-Verlag Berlin Heidelberg.

The present study aimed to investigate the effects of the treatment with α-lipoic acid (LA), a naturally occurring compound possessing antioxidant activity, on liver oxidant stress in a rat model of streptozotocin (STZ)-induced diabetes by examining potential mechanistic points that influence changes in the expression of antioxidant enzymes such as catalase (CAT) and CuZn/Mn superoxide dismutase(s) (SOD). LA was administered for 4 weeks by daily intraperitoneal injections (10 mg/kg) to STZ-induced diabetic rats, starting from the last STZ treatment. LA administration practically normalised the activities of the indicators of hepatocellular injury, alanine and aspartate aminotransferases, and lowered oxidative stress, as observed by the thiobarbituric acid-reactive substance assay, restored the reduced glutathione:glutathione disulphide ratio and increased the protein sulfhydryl group content. The lower level of DNA damage detected by the comet assay revealed that LA reduced cytotoxic signalling, exerting a hepatoprotective effect. The LA-treated diabetic rats displayed restored specific enzymatic activities of CAT, CuZnSOD and MnSOD. Quantitative real-time PCR analysis showed that LA restored CAT gene expression to its physiological level and increased CuZnSOD gene expression, but the gene expression of MnSOD remained at the diabetic level. Although the amounts of CAT and CuZnSOD protein expression returned to the control levels, the protein expression of MnSOD was elevated. These results suggested that LA administration affected CAT and CuZnSOD expression mainly at the transcriptional level, and MnSOD expression at the post-transcriptional level. The observed LA-promoted decrease in the O-GlcNAcylation of extracellular signal-regulated kinase, protein 38 kinase, NF-κB, CCAAT/enhancer-binding protein and the antioxidative enzymes themselves in diabetic rats suggests that the regulatory mechanisms that supported the changes in antioxidative enzyme expression were also influenced by post-translational mechanisms. © 2013 The Authors.

The present study aimed to investigate the effects of the treatment with α-lipoic acid (LA), a naturally occurring compound possessing antioxidant activity, on liver oxidant stress in a rat model of streptozotocin (STZ)-induced diabetes by examining potential mechanistic points that influence changes in the expression of antioxidant enzymes such as catalase (CAT) and CuZn/Mn superoxide dismutase(s) (SOD). LA was administered for 4 weeks by daily intraperitoneal injections (10 mg/kg) to STZ-induced diabetic rats, starting from the last STZ treatment. LA administration practically normalised the activities of the indicators of hepatocellular injury, alanine and aspartate aminotransferases, and lowered oxidative stress, as observed by the thiobarbituric acid-reactive substance assay, restored the reduced glutathione:glutathione disulphide ratio and increased the protein sulfhydryl group content. The lower level of DNA damage detected by the comet assay revealed that LA reduced cytotoxic signalling, exerting a hepatoprotective effect. The LA-treated diabetic rats displayed restored specific enzymatic activities of CAT, CuZnSOD and MnSOD. Quantitative real-time PCR analysis showed that LA restored CAT gene expression to its physiological level and increased CuZnSOD gene expression, but the gene expression of MnSOD remained at the diabetic level. Although the amounts of CAT and CuZnSOD protein expression returned to the control levels, the protein expression of MnSOD was elevated. These results suggested that LA administration affected CAT and CuZnSOD expression mainly at the transcriptional level, and MnSOD expression at the post-transcriptional level. The observed LA-promoted decrease in the O-GlcNAcylation of extracellular signal-regulated kinase, protein 38 kinase, NF-κB, CCAAT/enhancer-binding protein and the antioxidative enzymes themselves in diabetic rats suggests that the regulatory mechanisms that supported the changes in antioxidative enzyme expression were also influenced by post-translational mechanisms. © 2013 The Authors.

Introduction: Beta cell dysfunction by loss of beta cell identity, dedifferentiation, and the presence of polyhormonal cells are main characteristics of diabetes. The straightforward strategy for curing diabetes implies reestablishment of pancreatic beta cell function by beta cell replacement therapy. Aristaless-related homeobox (Arx) gene encodes protein which plays an important role in the development of pancreatic alpha cells and is a main target for changing alpha cell identity. Results: In this study we used CRISPR/dCas9-based epigenetic tools for targeted hypermethylation of Arx gene promoter and its subsequent suppression in mouse pancreatic αTC1-6 cell line. Bisulfite sequencing and methylation profiling revealed that the dCas9-Dnmt3a3L-KRAB single chain fusion constructs (EpiCRISPR) was the most efficient. Epigenetic silencing of Arx expression was accompanied by an increase in transcription of the insulin gene (Ins2) mRNA on 5th and 7th post-transfection day, quantified by both RT-qPCR and RNA-seq. Insulin production and secretion was determined by immunocytochemistry and ELISA assay, respectively. Eventually, we were able to induce switch of approximately 1% of transiently transfected cells which were able to produce 35% more insulin than Mock transfected alpha cells. Conclusion: In conclusion, we successfully triggered a direct, transient switch of pancreatic alpha to insulin-producing cells opening a future research on promising therapeutic avenue for diabetes management. Copyright © 2023 Đorđević, Stepper, Feuerstein-Akgoz, Gerhauser, Paunović, Tolić, Rajić, Dinić, Uskoković, Grdović, Mihailović, Jurkowska, Jurkowski, Jovanović and Vidaković.

Introduction The role of tumor necrosis factor-α (TNFα) is well documented in pathogenesis of chronic periodontitis (CP) and type 2 diabetes (T2D). Considering short half-life of TNFα, tumor necrosis factor receptor-2 (TNFR2) is used as prosperous surrogate marker of TNFα activity. Objective The aim was to detect TNFR2 serum concentration and correlate it with periodontal destruction in patients with diagnosed T2D and nondiabetics. Methods The study included 85 patients divided into three groups: T2D + CP (group T2D, n = 34); nondiabetics + CP (Group PD, n = 27); and healthy controls (group HC, n = 24). T2D was diagnosed according to WHO criteria (2013) and periodontitis was diagnosed using International Workshop for a Classification of Periodontal Diseases and Conditions criteria (1999). TNFR2 level was measured by enzyme-linked immunosorbent assay (ELISA). Results There was no difference in TNFR2 level among the groups (Kruskal–Wallis, p = 0.482). Significant correlation (Pearson’s correlation coefficient) was observed between clinical attachment loss (CAL) and TNFR2 concentration in PD group (rp = -0.460, p = 0.016). In T2D group, correlations were observed between TNFR2 concentration and CAL (rp = 0.363, p = 0.005) and periodontal inflamed surface area (PISA) (rp = 0.345, p = 0.046) and periodontal epithelial surface area (PESA) (rp = 0.578, p = 0.000). Conclusion Higher concentration of TNFR2 was associated with higher CAL, PESA, and PISA scores in T2D group. Contrary to that, nondiabetics with higher values of CAL exhibited lower concentration of TNFR2, presenting potential protective effect on periodontal destruction. These results imply that diabetes may alter TNFR2 secretion originated from periodontium. © 2016. Srpski Arhiv za Celokupno Lekarstvo. All right reserved.