Oxidant resistance in a yeast mutant deficient in the Sit4 phosphatase

Resistance to thiol oxidation can arise from mutations altering redox homeostasis. A Saccharomyces cerevisiae sit4-110 mutant is here described, which was isolated as resistant to the thiol-specific oxidant dipyridyl disulfide (DPS) and which contains a single-residue substitution in the SIT4 gene. Sit4p is a protein phosphatase with multiple roles in signal transduction through the target-of-rapamycin (TOR) pathway. We found that sit4-110 elevates the levels of glutathione. However, this cannot be the (only) cause for the DPS-resistance, since sit4-110 also conferred DPS/H₂O₂-resistance in a glutathione-deficient strain. Of the known Sit4p substrates, only Tip41p is involved in DPS-resistance; both Δtip41 deletion and overexpression of the Tip41p target Tap42p resulted in increased DPS-resistance. Thus, the role of Sit4p in DPS-tolerance differs from its role during TOR-inactivation and salt stress. In view of Tap42p’s known involvement in actin homeostasis, sit4-110 could compensate for putative actin-related defects caused by DPS. However, sit4-110 has pronounced actin polarization defects under both absence and presence of DPS. A relation between actin homeostasis and DPS resistance of sit4-110 cannot be ruled out, but our results suggest that unknown pathways might be involved in DPS resistance through mechanisms involving the Sit4p and/or Tap42p function(s).     

Diallyl-disulfide,an organosulfur compound of garlic,attenuates airway inflammation via activation of the Nrf-2/HO-1 pathway and NF-kappaB suppression

Diallyl disulfide (DADS) is a major organosulfur compound found in garlic oil that is widely used as a flavoring agent. In this study, we evaluated the effects of DADS on airway inflammation using an ovalbumin-induced model of allergic asthma and RAW264.7 cells. DADS decreased nitric oxide production with a reduction in the levels of interleukins (IL)-1β and IL-6 in RAW264.7 cells stimulated with LPS. DADS also reduced the expression of proinflammatory proteins including inducible nitric oxide synthase (iNOS), nuclear factor (NF)-κB, and matrix metalloproteinase (MMP)-9, and it enhanced the expression of antioxidant proteins including Nrf-2 and hemeoxygenase (HO)-1. In in vivo experiments, DADS decreased the inflammatory cell count in the bronchoalveolar lavage fluid (BALF) with IL-4, IL-5, IL-13, and immunoglobulin (Ig) E. These results were consistent with the histological analysis. DADS attenuated the airway inflammation and mucus hypersecretion induced by OVA challenge. In addition, DADS induced the activation of Nrf-2 and the expression of HO-1. In contrast, DADS reduced the activation of NF-κB, iNOS and MMP-9. In conclusion, DADS reduced the airway inflammation via regulation of Nrf-2/HO-1 and NF-κB. These results suggest that DADS might represent a useful new oral therapy to treat allergic asthma.     

CS2暴露与工人神经系统症状及体征关系的研究

研究二硫化碳暴露对粘胶纤维工人神经系统症状及体征的影响,在某化纤厂进行了一项横断面研究,共调查了CS₂作业工人326名,对照组105名.低浓度暴露组车间空气中二硫化碳浓度低于国家最高容许浓度10mg/m³,高浓度组多数接触浓度约为31mg/m³.统计学处理由SAS软件包完成,方法为非条件多元Logistic回归.分析中调整了诸如年龄、性别、工龄、体质指数、吸烟、饮酒、文化程度、婚姻状况等因素.结果低浓度CS₂暴露即可导致作业工人神经系统阳性症状发生的危险性较对照组明显升高,并表现出二硫化碳暴露对神经系统阳性症状的剂量-反应关系,而神经系统体征除温度觉外改变均不显着.此结果提示低浓度CS₂对工人神经系统的影响不容忽视     

饮酒对尿2 -硫代噻唑烷-4-羧酸排泄的影响

目的观察饮酒对二硫化碳(CS2)接触者及非接触者尿2-硫代噻唑烷4羧酸(TTCA)排泄的影响。方法(1)男性非接触CS2志愿者10人,一次饮用38。白酒150ml或250ml,高效液相色谱法观察其尿TTCA排泄动态;(2)CS2作业男工152人,非接触者60人,分别收集班末尿和晨尿进行TTCA测定并进行问卷调查;同时进行个体空气采样和CS2浓度气相色谱法测定。结果非接触者一次饮白酒150ml后3h尿TTCA水平达峰值,12h后降至饮前水平(餐前0．5h,饮酒后1、3、12h中位数分别为0．045、0．068、0．099、0．046mg/gCr,n=10);TTCA水平随饮白酒剂量的增加而增高,饮0、150、250ml白酒者TTCA水平(中位数)分别为0．036、0．064、0．609mg/gCr(n=5,饮后3h)。CS2浓度为≤10．0、10．1～50．0、>50．0mg/m3时,CS2接触者TTCA有随CS2浓度增高而上升的趋势;对照组中饮白酒和啤酒者TTCA水平似高于不饮者,而接触组TTCA水平则随饮酒指数的增加而呈降低趋势。结论大量饮酒可影响尿TTCA水平,在进行CS2生物监测时,应避免在大量饮酒后12h内采集尿样,以避免饮酒对监测结果的干扰作用。     

氧化还原敏感型靶向纳米给药系统的研究进展

理想的肿瘤靶向给药系统应在肿瘤部位高度累积且快速释放药物,而在血液循环中无泄漏,利用肿瘤环境改变的氧化还原状态及细胞内外的谷胱甘肽差异,结合纳米给药系统,可实现精准肿瘤靶向.本文对氧化还原敏感型靶向纳米给药系统的原理、氧化还原敏感键及其构建方法进行了介绍,并对基于脂质体、纳米粒、纳米胶束、纳米凝胶4种载体的不同氧化还原...     

Thioether side chain cyclization for helical peptide formation: inhibitors of estrogen receptor–coactivator interactions

Abstract: Cystine, lanthionine, and cystathionine containing cyclic peptides incorporating the signature nuclear receptor (NR) box (LXXLL) motif have been synthesized and the abilities of these peptides to inhibit estrogen receptor (ER)–coactivator interactions have been determined. We found that helicity of these peptides directly correlated with their bioactivity. Cystathionine proved to be a redox‐stable, isosteric replacement for the cystine disulfide. Cystathionine containing peptide 3 showed higher helical character and a lower inhibition constant (Ki, 7 nm ) when compared with its cystine counterpart.     

Short Toxin-like Proteins Attack the Defense Line of Innate Immunity

ClanTox (classifier of animal toxins) was developed for identifying toxin-like candidates from complete proteomes. Searching mammalian proteomes for short toxin-like proteins (coined TOLIPs) revealed a number of overlooked secreted short proteins with an abundance of cysteines throughout their sequences. We applied bioinformatics and data-mining methods to infer the function of several top predicted candidates. We focused on cysteine-rich peptides that adopt the fold of the three-finger proteins (TFPs). We identified a cluster of duplicated genes that share a structural similarity with elapid neurotoxins, such as α-bungarotoxin. In the murine proteome, there are about 60 such proteins that belong to the Ly6/uPAR family. These proteins are secreted or anchored to the cell membrane. Ly6/uPAR proteins are associated with a rich repertoire of functions, including binding to receptors and adhesion. Ly6/uPAR proteins modulate cell signaling in the context of brain functions and cells of the innate immune system. We postulate that TOLIPs, as modulators of cell signaling, may be associated with pathologies and cellular imbalance. We show that proteins of the Ly6/uPAR family are associated with cancer diagnosis and malfunction of the immune system.     

不同生殖阶段CS2暴露对小鼠粘附分子影响

目的 研究不同生殖阶段暴露于二硫化碳(CS₂)对小鼠子宫和胚胎组织粘附分子表达水平的影响。方法 分别给处于卵泡发育期、胚胎植入期(分为植入早期和晚期)的雌性小鼠腹腔注射CS₂(631.4 mg/kg),每天1次,连续2 d,于受孕第9d收集样本,用western blotting测定胚胎和子宫组织中粘附分子纤维粘连蛋白(FN)及其受体蛋白整合素β₁的表达水平。结果 与对照组比较,胚胎植入期染毒组胚胎和子宫组织中的FN与整合素β₁表达水平各分别下降了54.8%、10.4%和52.5%、21.1%,差异均有统计学意义(P<0.05);在卵泡发育期染毒组,子宫组织中FN与整合素β₁表达水平分别下降了69.4%和16.0%,差异有统计学意义(P<0.05),但胚胎组织中仅见FN表达水平明显降低(P<0.01);与对照组比较,植入期染毒组的胚泡植入数减少了37.5%,差异有统计学意义(P<0.01),但卵泡发育期染毒组仅表现为轻微下降(P>10.05)。结论 胚胎植入期暴露于CS₂明显减少小鼠胚胎和子宫组织中粘附分子FN和整合素β的表达水平,粘附分子表达水平的降低与胚胎植入障碍相关联。     

Selective expression of Kir6.1 protein in different vascular and non-vascular tissues

K(ATP) channels are composed of pore-forming subunits Kir6.x and auxiliary subunits SURx. These channels play important roles in modulating the contractility of vascular smooth muscle cells (SMCs) by altering membrane potentials. The molecular basis of K(ATP) channels in vascular SMCs is unclear and the expression of different K(ATP) channel subunits at protein level in various tissues still undetermined. In this study, using an anti-Kir6.1 antibody, we detected the expression of Kir6.1 proteins in rat vascular tissues including mesenteric artery, pulmonary artery, aorta, and tail artery. Kir6.1 proteins were also identified in heart and other non-vascular tissues including spleen and brain, but they were undetectable in liver and kidney. Immunocytochemical study revealed the expression of Kir6.1 proteins in cultured rat thoracic aortic SMCs. Using the whole-cell patch-clamp technique, it was found that the intracellularly applied anti-Kir6.1 antibody significantly inhibited K(ATP) channel currents in HEK-293 cells that were stably transfected with Kir6.1 cDNA. A better understanding of differential expression of Kir6.1 proteins in various vascular and non-vascular tissues may help discern different molecular basis and functions of K(ATP) channel complexes in these tissues.