Search Results (6)

Background: Urinary stones (urolithiasis) have been categorized as kidney stones (renal calculus), ureteric stones (ureteral calculus and ureterolith), bladder stones (bladder calculus), and urethral stones (urethral calculus); however, the mechanisms underlying their promotion and related injuries in glomerular and tubular cells remain unclear. Although lifestyle-related diseases (LSRDs) such as hyperglycemia, type 2 diabetic mellitus, non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, and cardiovascular disease are risk factors for urolithiasis, the underlying mechanisms remain unclear. Recently, heat shock protein 90 (HSP90) on the membrane of HK-2 human proximal tubular epithelium cells has been associated with the adhesion of urinary stones and cytotoxicity. Further, HSP90 in human pancreatic and breast cells can be modified by various advanced glycation end-products (AGEs), thus affecting their function. Hypothesis 1: We hypothesized that HSP90s on/in human proximal tubular epithelium cells can be modified by various types of AGEs, and that they may affect their functions and it may be a key to reveal that LSRDs are associated with urolithiasis. Hypothesis 2: We considered the possibility that Japanese traditional medicines for urolithiasis may inhibit AGE generation. Of Choreito and Urocalun (the extract of Quercus salicina Blume/Quercus stenophylla Makino) used in the clinic, Choreito is a Kampo medicine, while Urocalun is a characteristic Japanese traditional medicine. As Urocalun contains quercetin, hesperidin, and p-hydroxy cinnamic acid, which can inhibit AGE generation, we hypothesized that Urocalun may inhibit the generation of AGE-modified HSP90s in human proximal tubular epithelium cells. Full article

Triosephosphate isomerase (TPI) dysfunction is a critical factor in diverse pathological conditions. Deficiencies in TPI lead to the accumulation of toxic methylglyoxal (MGO), which induces non-enzymatic post-translational modifications, thus compromising protein stability and leading to misfolding. This study investigates how specific TPI mutations (E104D, N16D, and C217K) affect the enzyme’s structural stability when exposed to its substrate glyceraldehyde 3-phosphate (G3P) and MGO. We employed circular dichroism, intrinsic fluorescence, native gel electrophoresis, and Western blotting to assess the structural alterations and aggregation propensity of these TPI mutants. Our findings indicate that these mutations markedly increase TPI’s susceptibility to MGO-induced damage, leading to accelerated loss of enzymatic activity and enhanced protein aggregation. Additionally, we observed the formation of MGO-induced adducts, such as argpyrimidine (ARGp), that contribute to enzyme inactivation and aggregation. Importantly, the application of MGO-scavenging molecules partially mitigated these deleterious effects, highlighting potential therapeutic strategies to counteract MGO-induced damage in TPI-related disorders. Full article

Advanced glycation end-products (AGEs) have recently been implicated in the onset/progression of lifestyle-related diseases (LSRDs); therefore, the suppression of AGE-induced effects may be used in both the prevention and treatment of these diseases. Various AGEs are produced by different biological pathways in the body. Glyceraldehyde (GA) is an intermediate of glucose and fructose metabolism, and GA-derived AGEs (GA-AGEs), cytotoxic compounds that accumulate and induce damage in mammalian cells, contribute to the onset/progression of LSRDs. The following GA-AGE structures have been detected to date: triosidines, GA-derived pyridinium compounds, GA-derived pyrrolopyridinium lysine dimers, methylglyoxal-derived hydroimidazolone 1, and argpyrimidine. GA-AGEs are a key contributor to the formation of toxic AGEs (TAGE) in many cells. The extracellular leakage of TAGE affects the surrounding cells via interactions with the receptor for AGEs. Elevated serum levels of TAGE, which trigger different types of cell damage, may be used as a novel biomarker for the prevention and early diagnosis of LSRDs as well as in evaluations of treatment efficacy. This review provides an overview of the structures of GA-AGEs. Full article

Advanced glycation end products (AGEs), which can have multiple structures, are formed at the sites where the carbonyl groups of reducing sugars bind to the free amino groups of proteins through the Maillard reaction. Some AGE structures exhibit fluorescence, and this fluorescence has been used to measure the formation and quantitative changes in carbonylated proteins. Recently, fluorescent AGEs have also been used as an index for the evaluation of compounds that inhibit protein glycation. However, the systems used to generate fluorescent AGEs from the reaction of reducing sugars and proteins used for the evaluation of antiglycation activity have not been determined through appropriate research; thus, problems remain regarding sensitivity, quantification, and precision. In the present study, using methylglyoxal (MGO), a reactive carbonyl compound to induce glycation, a comparative analysis of the mechanisms of formation of fluorescent substances from several types of proteins was conducted. The analysis identified hen egg lysozyme (HEL) as a protein that produces stronger fluorescent AGEs faster in the Maillard reaction with MGO. It was also found that the AGE structure produced in MGO-induced in HEL was argpyrimidine. By optimizing the reaction system, we developed a new evaluation method for compounds with antiglycation activity and established an efficient evaluation method (HEL–MGO assay) with greater sensitivity and accuracy than the conventional method, which requires high concentrations of bovine serum albumin and glucose. Furthermore, when compounds known to inhibit glycation were evaluated using this method, their antiglycation activities were clearly and significantly measured, demonstrating the practicality of this method. Full article

Sugar carbonyl groups interact with protein amino groups, forming toxic components referred to as advanced glycation end products (AGEs). The glycation system (BSA, a model protein, and fructose) was incubated for five weeks at 37 °C in the presence and absence of Stevia leaf extract. The results indicated that the leaf extract (0.5 mg/mL) decreased the incidence of browning (70.84 ± 0.08%), fructosamine (67.27 ± 0.08%), and carbonyl content (64.04 ± 0.09%). Moreover, we observed an 81 ± 8.49% reduction in total AGEs. The inhibition of individual AGE (argpyrimidine, vesper lysine, and pentosidine) was ~80%. The decrease in the protein aggregation was observed with Congo red (46.88 ± 0.078%) and the Thioflavin T (31.25 ± 1.18%) methods in the presence of Stevia leaf extract. The repercussion of Stevia leaf extract on DNA glycation was examined using agarose gel electrophoresis, wherein the DNA damage was reversed in the presence of 1 mg/mL of leaf extract. When the HDF cell line was treated with 0.5 mg/mL of extract, the viability of cells decreased by only ~20% along with the same cytokine IL-10 production, and glucose uptake decreased by 28 ± 1.90% compared to the control. In conclusion, Stevia extract emerges as a promising natural agent for mitigating glycation-associated challenges, holding potential for novel therapeutic interventions and enhanced management of its related conditions. Full article

Increased blood glucose in diabetic individuals results in the formation of advanced glycation end products (AGEs), causing various adverse effects on kidney cells, thereby leading to diabetic nephropathy (DN). In this study, the antiglycative potential of Swertiamarin (SM) isolated from the methanolic extract of E. littorale was explored. The effect of SM on protein glycation was studied by incubating bovine serum albumin with fructose at 60 °C in the presence and absence of different concentrations of swertiamarin for 24 h. For comparative analysis, metformin was also used at similar concentrations as SM. Further, to understand the role of SM in preventing DN, in vitro studies using NRK-52E cells were done by treating cells with methylglyoxal (MG) in the presence and absence of SM. SM showed better antiglycative potential as compared to metformin. In addition, SM could prevent the MG mediated pathogenesis in DN by reducing levels of argpyrimidine, oxidative stress and epithelial mesenchymal transition in kidney cells. SM also downregulated the expression of interleukin-6, tumor necrosis factor-α and interleukin-1β. This study, for the first time, reports the antiglycative potential of SM and also provides novel insights into the molecular mechanisms by which SM prevents toxicity of MG on rat kidney cells. Full article