Mechanism of protein S-nitrosylation modification mediated severe acute pancreatitis / 中国医师杂志

Objective:This study aims to explore the pathogenic roles of protein S-nitrosylation modification in the development of severe acute pancreatitis, and provide new insights into the molecular mechanisms driving acute pancreatitis development.Methods:Thirty two Sprague Dawley (SD) rats were randomly divided into sham operation group, mild acute pancreatitis (MAP) group, severe acute pancreatitis (SAP) group and SAP + N-nitro-L-arginine methyl ester (L-NAME) group (treated with nitric oxide synthase inhibitor), 8 rats in each group. All rats were sacrificed to take blood from heart and pancreatic tissues 24 h after model construction. Total protein S-nitrosylation modification level in pancreatic tissues was quantitated by the biotin-switch method, followed by histological evaluation via hematoxylin and eosin (HE) staining. The serum endotoxin, D-lactic acid, diamine oxidase, interleukin-6 and tumor necrosis factor-ɑ(TNF-ɑ), amylase, alanine aminotransferase, urea nitrogen and calcium ions in rat were detected. Pearson correlation analysis was used to analyze the correlation between each index and protein S-nitrosylation.Results:Compared with the sham operation group, the modification level of protein S-nitrosylation in pancreatic tissue of MAP group increased significantly ( P<0.05); Compared with MAP group, the modification level of protein S-nitrosylation in pancreatic tissue of SAP group increased significantly ( P<0.05); Compared with SAP group, the modification level of protein S-nitrosylation in pancreatic tissue of SAP + L-NAME group decreased significantly ( P<0.05). HE staining showed that the degree of pancreatic necrosis and inflammatory cell infiltration in SAP + L-NAME group were significantly weaker than those in SAP group. The concentrations of serum endotoxin, diamine oxidase, D-lactic acid, IL-6 and TNF-ɑ, amylase, alanine aminotransferase, and urea nitrogen in the MAP group were significantly higher than those in the sham operation group (all P<0.05); The above indexes in SAP group were significantly higher than those in MAP group and sham operation group (all P<0.05); The above indexes in SAP + L-NAME group were significantly lower than those in SAP group (all P<0.05). The serum IL-6 and TNF-ɑ levels in rats with acute pancreatitis were positively correlated with protein S-nitrosylation in pancreatic tissue (all P<0.05). Conclusions:Protein S-nitrosylation modification plays essential roles in the development and progression of severe acute pancreatitis.

Research progress of S-nitrosoglutathione reductase inhibitors in the regulation of cerebral injury after cardiac arrest-cardiopulmonary resuscitation / 中华危重病急救医学

The cerebral ischemia-reperfusion injury (CIRI) after the cardiac arrest (CA)-cardiopulmonary resuscitation (CPR) was a complex pathophysiology process. Nitric oxide (NO) is a small molecule that mediates cell signal transduction in vivo and plays an important role in the regulation of brain function during ischemia/reperfusion (I/R). S-nitrosoglutathione reductase (GSNOR) inhibitor can regulate the synthesis and release of NO in vivo and has a protective effect on CIRI. Therefore, early administration of GSNOR to CA-CPR patients could be the main treatment method to improve the prognosis of those patients. A large number of studies have been done to improve the prognosis of CA-CPR in recent years. In order to provide reference for further research on the treatment and brain protection of CIRI after CA-CPR, the article reviewed the main mechanisms of brain injury after CA-CPR, the protective effect and mechanism of NO on cerebral I/R injury, the production and regulation of NO, in vivo, and the protective effect of GSNOR inhibitors on CIRI, especially the research progress of GSNOR inhibitors.

DeepNitro: Prediction of Protein Nitration and Nitrosylation Sites by Deep Learning / 基因组蛋白质组与生物信息学报·英文版

Protein nitration and nitrosylation are essential post-translational modifications (PTMs) involved in many fundamental cellular processes. Recent studies have revealed that excessive levels of nitration and nitrosylation in some critical proteins are linked to numerous chronic diseases. Therefore, the identification of substrates that undergo such modifications in a site-specific manner is an important research topic in the community and will provide candidates for targeted therapy. In this study, we aimed to develop a computational tool for predicting nitration and nitrosylation sites in proteins. We first constructed four types of encoding features, including positional amino acid distributions, sequence contextual dependencies, physicochemical properties, and position-specific scoring features, to represent the modified residues. Based on these encoding features, we established a predictor called DeepNitro using deep learning methods for predicting protein nitration and nitrosylation. Using n-fold cross-validation, our evaluation shows great AUC values for DeepNitro, 0.65 for tyrosine nitration, 0.80 for tryptophan nitration, and 0.70 for cysteine nitrosylation, respectively, demonstrating the robustness and reliability of our tool. Also, when tested in the independent dataset, DeepNitro is substantially superior to other similar tools with a 7%-42% improvement in the prediction performance. Taken together, the application of deep learning method and novel encoding schemes, especially the position-specific scoring feature, greatly improves the accuracy of nitration and nitrosylation site prediction and may facilitate the prediction of other PTM sites. DeepNitro is implemented in JAVA and PHP and is freely available for academic research at http://deepnitro.renlab.org.

Pathophysiological Role of S-Nitrosylation and Transnitrosylation Depending on S-Nitrosoglutathione Levels Regulated by S-Nitrosoglutathione Reductase

Nitric oxide (NO) mediates various physiological and pathological processes, including cell proliferation, differentiation, and inflammation. Protein S-nitrosylation (SNO), a NO-mediated reversible protein modification, leads to changes in the activity and function of target proteins. Recent findings on protein-protein transnitrosylation reactions (transfer of an NO group from one protein to another) have unveiled the mechanism of NO modulation of specific signaling pathways. The intracellular level of S-nitrosoglutathione (GSNO), a major reactive NO species, is controlled by GSNO reductase (GSNOR), a major regulator of NO/SNO signaling. Increasing number of GSNOR-related studies have shown the important role that denitrosylation plays in cellular NO/SNO homeostasis and human pathophysiology. This review introduces recent evidence of GSNO-mediated NO/SNO signaling depending on GSNOR expression or activity. In addition, the applicability of GSNOR as a target for drug therapy will be discussed in this review.

Allicin suppresses atherosclerosis by up-regulating protein S-nitrosylation / 西安交通大学学报(医学版)

Objective To investigate the effect of allicin on the development of atherosclerosis in apoE-/-mice and explore its underlying mechanism from the perspective of protein S-nitrosylation.Methods Thirty male apoE-/- mice were randomly divided into 3 groups:control group (saline,ig),low-dose group (allicin,9 mg/kg·d, ig)and high-dose group (allicin,18 mg/kg·d,ig).They were fed with high cholesterol diet for 12 weeks.The levels of plasma lipids,oxidized-LDL (ox-LDL),malondialdehyde,tumor necrosis factor-alpha and nitric oxide (NO)were measured.The atherosclerotic lesions in aortic root were evaluated after hematoxylin and eosin staining and elastica van Gieson and immunohistochemical staining,respectively.Furthermore,in vitro experiments were performed using human umbilical vein endothelial cells (HUVECs).The HUVECs were treated with allicin (10μmol/L or 20 μmol/L)for 24 hours in the presence of ox-LDL (50 μg/mL).The level of NO in supernatant was measured by a nitrate/nitrite assay. The protein S-nitrosylation of the HUVECs was detected through immunofluorescence.Results The histological analysis revealed that allicin treatment not only significantly decreased the areas of the atherosclerotic lesion (all P <0.05)but also suppressed the macrophage accumulation and smooth muscle cell proliferation in the lesion.There was no significant difference in the levels of plasma lipids between control and treated groups.However,allicin exerted obvious anti-oxidative and anti-inflammatory effects. Interestingly,the allicin treatment led to marked increase of the plasma NO level (P <0.05)and aortic protein S-nitrosylation.The experiments in vitro further proved that the allicin up-regulated the levels of NO and protein S-nitrosylation in HUVECs treated with ox-LDL (P < 0.01 ).Conclusion Allicin can inhibit the development of atherosclerosis.The mechanism is associated with the up-regulation of protein S-nitrosylation in endothelial cells, which plays an important role in anti-oxidization and anti-inflammation.

Establishment and application of determination of glyphosate poisoning method by UV spectrophotometry / 国际检验医学杂志

Objective To establish a qualitative and quantitative determination of glyphosate in serum using ultraviolet spectro-photometry(UV) to provide basis for clinical diagnosing and treating glyphosate poisoning .Methods The mixture of 0 .5 mL serum and 0 .2 mL 10% methanol solution of perchloric acid was shocked and centrifuged with 10 000 r/min for 5 min .A nitrosyla-tion reaction conducted on supernatant and 50 μL serum nitrosylation liquid was detected by UV scanning .Results The results of serum theophylline absorption maxima was(243 ± l) nm and the concentration of 10 .0-60 .0 μg/mL range linear regression equa-tion was Y=0 .0173 8X+0 .036 3(r= 0 .999 8) .The recovery rate was from 85 .5% to 102 .4% and the relative standard deviation (RSD) was from 3 .50% to 4 .90% .The intra-day and inter-day RSD were 3 .79% -5 .10% and 3 .88% -4 .55% .The minimum de-tectable concentration was 5μg/mL .Conclusion This method is simple ,rapid and accurate results for detecting glyphosate poison-ing .

Nitric Oxide Inhibits Delayed Rectifier Potassium Currents in Cultured Hippocampal Neurons via S-Nitrosylation / 生物化学与生物物理进展

The modulating action and mechanism of endogenous nitric oxide (NO) on the delayed rectifier potassium currents in cultured hippocampal neurons were examined using whole-cell patch clamp techniques. L-arginine (L-Arg, 2 mmol/L), a substrate of NO synthases, significantly suppressed the delayed rectifier K+ currents in hippocampal neurons, while its isomer D-arginine (D-Arg, 2 mmol/L) exerted no effect. Moreover, pretreatment with NO synthase inhibitor L-NAME (0.5 mmol/L) completely blocked the suppressing effect by L-Arg, indicating that L-Arg exerted its modulation by producing NO but not by itself. No effect was found on the L-Arg-induced inhibition by 10 min pretreatment of 10 |?mol/L ODQ (a specific inhibitor of guanylate cyclase). In contrast, thiol-alkylating agent N-ethylmaleimide (1 mmol/L) completely precluded L-Arg-induced inhibition on the whole K+ currents. The results indicate that endogenous NO modulates the delayed rectifier K+ currents in cultured hippocampal neurons mostly through S-nitrosylation.