Understanding human thiol dioxygenase enzymes: structure to function,and biology to pathology

Amino acid metabolism is a significant metabolic activity in humans, especially of sulphur‐containing amino acids, methionine and cysteine (Cys). Cys is cytotoxic and neurotoxic in nature; hence, mammalian cells maintain a constant intracellular level of Cys. Metabolism of Cys is mainly regulated by two thiol dioxygenases: cysteine dioxygenase (CDO) and 2‐aminoethanethiol dioxygenase (ADO). CDO and ADO are the only human thiol dioxygenases reported with a role in Cys metabolism and localized to mitochondria. This metabolic pathway is important in various human disorders, as it is responsible for the synthesis of antioxidant glutathione and is also for the synthesis of hypotaurine and taurine. CDO is the most extensively studied protein, whose high‐resolution crystallographic structures have been solved. As compared to CDO, ADO is less studied, even though it has a key role in cysteamine metabolism. To further understand ADO's structure and function, the three‐dimensional structures have been predicted from I‐TASSER and SWISS‐MODEL servers and validated with PROCHECK software. Structural superimposition approach using iPBA web server further confirmed near‐identical structures (including active sites) for the predicted protein models of ADO as compared to CDO. In addition, protein–protein interaction and their association in patho‐physiology are crucial in understanding protein functions. Both ADO and CDO interacting partner profiles have been presented using STRING database. In this study, we have predicted a 3D model structure for ADO and summarized the biological roles and the pathological consequences which are associated with the altered expression and functioning of ADO and CDO in case of cancer, neurodegenerative disorders and other human diseases.     

miR-199a靶向CSRP2对人风湿关节炎滑膜成纤维细胞的增殖、侵袭和炎症因子分泌的影响

目的:研究miR-199a对人风湿关节炎滑膜成纤维细胞MH7A增殖、侵袭和炎症因子分泌的影响及其机制.方法:将miR-199a mimics或/和pcDNA3.1-CSRP2转染至MH7A细胞,再以100 mg/L脂多糖(LPS)处理.用实时荧光定量PCR(RT-qPCR)检测细胞中miR-199a、富含半胱氨酸和甘氨...     

N-acetyl cysteine restores brain glutathione loss in combined 2-cyclohexene-1-one and d-amphetamine-treated rats: relevance to schizophrenia and bipolar disorder

Oxidative stress and reduced brain levels of glutathione have been implicated in schizophrenia and bipolar disorder. N-acetyl cysteine (NAC) is a precursor of glutathione and has additional effects on glutamate neurotransmission, neurogenesis and inflammation. While NAC treatment has shown benefits in both schizophrenia and bipolar disorder, the mechanisms of action are largely unknown. Similarly, the interaction between oxidative stress and altered dopaminergic activities in psychiatric illness is not yet characterized. This study investigated the capacity of NAC in restoring brain glutathione depletion in rats that received 2-cyclohexene-1-one (CHX, 75 mg/kg), d-amphetamine (2.5mg/kg) or both. CHX, but not amphetamine, induced significant depletion of glutathione levels in the striatum and frontal cortex. Glutathione depletion was reversed by NAC (1000 mg/kg) in saline-treated and amphetamine-treated (frontal cortex only) rats. While NAC was shown to be beneficial in this model, the lack of additional glutathione depletion by amphetamine in combination with CHX does not support a summative interaction between oxidative stress and altered dopamine transmission.     

Functional effects of the inhibition of the cysteine protease activity of the major house dust mite allergen Der p 1 by a novel peptide-based inhibitor.

BACKGROUND: The house dust mite (HDM) Dermatophagoides pteronyssinus is an important source of allergens, which can cause allergic conditions. The cysteine protease activity of Der p 1 may enhance the potency of this major mite allergen through cleavage of CD23 and CD25 from the surface of immune cells, IgE independent mast cell activation, increases in epithelial cell permeability and inactivation of an endogenous serine protease inhibitor. Inhibition of the enzymatic activity of Der p 1 may therefore be of therapeutic benefit. OBJECTIVE: To examine the activity of PTL11028, a newly developed Der p 1 inhibitor, in a range of assays that directly or indirectly measure Der p 1 protease activity and to compare its activity to endogenous cysteine protease inhibitors. METHODS: The proteolytic activities of purified Der p 1 or HDM extract and inhibitory properties of PTL11028 were examined through cleavage of an artificial peptidyl substrate, cleavage of CD23 from human B cells and permeability studies on primary human bronchial epithelial cells. RESULTS: PTL11028 is a highly potent and specific Der p 1 inhibitor, being effective against both purified protease and Der p 1 within HDM extract. PTL11028 can completely inhibit Der p 1-mediated CD23 cleavage from human B cells and also reduces HDM-induced human bronchial epithelial cell permeability by 50%. Der p 1 is potently inhibited by cystatin A and to a lesser extent by cystatins C and E/M. CONCLUSION: PTL11028 is a highly potent and selective irreversible inhibitor of the cysteine protease activity of Der p 1, an activity that may be modulated in vivo by some human cystatins. PTL11028 prevents the Der p 1-mediated cleavage of CD23 from human B cells and significantly reduces HDM-induced permeabilization of the epithelial barrier. PTL11028 is an important tool to examine the biological effects of Der p 1 in a range of in vitro and in vivo model systems.     

Heterogeneous proteolytic specificity and activity of the house dust mite proteinase allergen Der p I

Background Exposure of the skin or respiratory tract to proteinases is frequently associated with allergic sensitization. This is of particular significance in the domestic indoor environment where the proteolytic activity of Der p I, the group I allergen of the house dust mite Dermatophagoides pteronyssinus, may influence the allergenicity of mites. Using class-specific proteinase inhibitors and active-site affinity chromatography, we have previously shown that Der p I exhibits a mixed cysteine-serine proteinase activity. Measurement of the amount of cleavage, however, did not determine whether the inhibitors used were targeting exactly the same proteolytic mechanism. Objective To resolve this issue, we have examined whether the cleavage specificity of the cysteine and serine proteinase activities of Der p I was the same. Methods HPLC and mass spectrometry were used to analyse and identify the products of a Der p I-digested peptide substrate and thus identify the peptide bonds cleaved. Results Der p I cleaves different peptide bonds, depending upon the class of proteolytic mechanism used. In the model peptide substrate insulin B chain, the cysteine and serine proteinase activities of Der p I showed preference for glutamic acid and arginine respectively in the P1 position. Conclusion These data suggest the existence of more than one mechanistic form of the allergen immunologically identified as Der p I. If proteolytic activity is indeed a function of allergenicity, this information may have important implications for the pathogenicity of Der p I and the ability of innate antiproteinase defences in the respiratory tract to prevent immune sensitization.     

Thiol‐water proton exchange of glutathione,cysteine, and N‐acetylcysteine: Implications for CEST MRI

Amide‐, amine‐, and hydroxyl‐water proton exchange can generate MRI contrast through chemical exchange saturation transfer (CEST). In this study, we show that thiol‐water proton exchange can also generate quantifiable CEST effects under near‐physiological conditions (pH = 7.2 and 37°C) through the characterization of the pH dependence of thiol proton exchange in phosphate‐buffered solutions of glutathione, cysteine, and N‐acetylcysteine. The spontaneous, base‐catalyzed, and buffer‐catalyzed exchange contributions to the thiol exchange were analyzed. The thiol‐water proton exchange of glutathione and cysteine was found to be too fast to generate a CEST effect around neutral pH due to significant base catalysis. The thiol‐water proton exchange of N‐acetylcysteine was found to be much slower, yet still in the fast‐exchange regime with significant base and buffer catalysis, resulting in a 9.5% attenuation of the water signal at pH 7.2 in a slice‐selective CEST NMR experiment. Furthermore, the N‐acetylcysteine thiol CEST was also detectable in human serum albumin and agarose phantoms.     

Defensins: Natural component of human innate immunity

The widespread use of antibiotics has contributed to a huge increase in the number of resistant bacteria. New classes of drugs are therefore being developed of which defensins are a potential source. Defensins are a group of antimicrobial peptides found in different living organisms, involved in the first line of defense in their innate immune response against pathogens. This review summarizes the results of studies of this family of human antimicrobial peptides (AMPs). There is a special emphasis on describing the entire group and individual peptides, history of their discovery, their functions and expression sites. The results of the recent studies on the use of the biologically active peptides in human medicine are also presented. The pharmaceutical potential of human defensins cannot be ignored, especially considering their strong antimicrobial activity and properties such as low molecular weight, reduced immunogenicity, broad activity spectrum and resistance to proteolysis, but there are still many challenges and questions regarding the possibilities of their practical application.     

支气管肺炎患儿治疗前后血清SIL-2R和白三烯测定的临床意义

目的：探讨了血清可溶性白细胞介素-2受体（SIL-2R）和半胱氨酰白三烯（LTS）水平在支气管肺炎患儿治疗前后的变化及意义。方法：应用ELISA对35例支气管肺炎患儿进行了血清SIL-2R和LTS测定，并与30例正常儿作比较。结果：支气管肺炎患儿在治疗前血清SIL-2R和LTS水平非常显著地高于正常儿组（P〈0.01）。治疗后2周后血清SIL-2R和LTS水平与正常儿比较无显著性差异（P〉0．05）。结论：检测支气管肺炎患儿血清中SIL-2R和LTS水平可作为病情预后判断的重要指标。     

Garlic compounds protect vascular endothelial cells from hydrogen peroxide-induced oxidant injury

Oxygen radical injury and lipid peroxidation have been suggested as major causes of cancer, atherosclerosis and the aging process. In this study, we determined in vitro the effect of aged garlic extract (AGE) and one of its components, S-allyl cysteine (SAC), on hydrogen peroxide (H₂O₂)-induced oxidant injury using bovine pulmonary artery endothelial cells (PAEC). After overnight preincubation with AGE or SAC, PAEC monolayers were exposed to H₂O₂ for 3 h. Cell viability, lactate dehydrogenase (LDH) release and lipid peroxidation were measured to assess oxidant injury. Pretreatment with AGE at 2–4 mg/mL or SAC at 4 mg/mL significantly reversed the loss of cell viability induced by 50 and 100 μm of H₂O₂. AGE or SAC also exhibited a dose-dependent inhibition of both LDH release and lipid peroxidation induced by 50 μM of H₂O₂. The results show that both AGE and SAC can protect vascular endothelial cells from oxidant injury. The data thus suggest that these compounds may be useful for retardation of the aging process and for prevention of cancer and atherosclerosis.     

功能性L-Cys-CdS纳米粒子共振光散射法测定脱氧核糖核酸

目的报道了功能性L-Cys-CdS纳米荧光探针的合成,纳米粒子水溶性好,稳定,且具有较好的荧光特性。方法以该纳米粒子为荧光探针,探讨了DNA对其的荧光猝灭作用。结果表明在Tris-HCL溶液中DNA对CdS的RLS有很好的猝灭,小牛胸腺DNA及鱼精DNA的线性范围及检测限分别为0.01 -1.0μg·mL-1, 8 ng·mL-1; 0.04 -1.5μg·mL-1, 10ng·mL-1。结论该方法简便、快速、灵敏,用于测定合成样品取得了满意的结果。