Comprehensive identification of novel post-translational modifications in cellular peroxiredoxin 6

Peroxiredoxin 6 (PRDX6), a 1-Cys peroxiredoxin, is a bifunctional enzyme acting both as a glutathione peroxidase and a phospholipase A2. However, the underlying mechanisms and their regulation mechanisms are not well understood. Because post-translational modifications (PTMs) have been shown to play important roles in the function of many proteins, we undertook, in this study, to identify the PTMs in PRDX6 utilizing proteomic tools including nanoUPLC-ESI-q-TOF MS/MS employing selectively excluded mass screening analysis (SEMSA) in conjunction with MOD(i) and MODmap algorithm. We chose PRDX6 obtained from liver tissues from two inbred mouse strains, C57BL/6J and C3H/HeJ, which vary in their susceptibility to high-fat diet-induced obesity and atherosclerosis, and a B16F10 melanoma cell line for this study. When PRDX6 protein samples were separated on 2D-PAGE based on pI, several PRDX6 spots appeared. They were purified and the low abundant PTMs in each PRDX6 spot were analyzed. Unexpected mass shifts (Δm = -34, +25, +64, +87, +103, +134, +150, +284 Da) observed at active site cysteine residue (Cys47) were quantified using precursor ion intensities. Mass differences of -34, +25, and +64 Da are presumed to reflect the conversion of cysteine to dehydroalanine, cyano, and Cys-SO(2) -SH, respectively. We also detected acrylamide adducts of sulfenic and sulfinic acids (+87 and +103 Da) as well as unknown modifications (+134, +150, +284 Da). Comprehensive analysis of these PTMs revealed that the PRDX6 exists as a heterogeneous mixture of molecules containing a multitude of PTMs. Several of these modifications occur at cysteine residue in the enzyme active site. Other modifications observed, in PRDX6 from mouse liver tissues included, among others, mono- and dioxidation at Trp and Met, acetylation at Lys, and deamidation at Asn and Gln. Comprehensive identification of the diverse PTMs occurring in this bifunctional PRDX6 enzyme should help understand how PRDX6 plays key roles in oxidative stresses.     

中国内蒙古龙胆属一新种——兴安龙胆(Gentiana hsinganica)

描述了龙胆科龙胆属一新种——兴安龙胆(Gentiana hsinganica),绘制了形态图并与近缘种条叶龙胆(G.manshurica)、三花龙胆(G.triflora)和朝鲜龙胆(G.uchiyamai)做了比较,主要区别特征为:茎生叶3枚轮生,花萼裂片极小并呈三角形,每朵花下的苞片明显长于花萼。     

Immunostimulatory effect of spinach aqueous extract on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages

We herein report the immunostimulatory effect of spinach aqueous extract (SAE) on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages. SAE significantly enhanced the production of interleukin (IL)-6 and tumor necrosis factor-α by both J774.1 cells and peritoneal macrophages by enhancing the expression levels of these cytokine genes. In addition, the phagocytosis activity of J774.1 cells was facilitated by SAE. Immunoblot analysis revealed that SAE activates mitogen-activated protein kinase and nuclear factor-κB cascades. It was found that SAE activates macrophages through not only TLR4, but also other receptors. The production of IL-6 was significantly enhanced by peritoneal macrophages from SAE-administered BALB/c mice, suggesting that SAE has a potential to stimulate macrophage activity in vivo. Taken together, these data indicate that SAE would be a beneficial functional food with immunostimulatory effects on macrophages.     

RNAi沉默lovF基因实现土曲霉一步法发酵生产辛伐他汀

辛伐他汀是重要的降胆固醇处方药物。莫那可林J是辛伐他汀合成过程的关键中间体,也是洛伐他汀生物合成的中间产物。为获得莫那可林J并通过一步法发酵生成辛伐他汀,构建了洛伐他汀生物合成关键基因lov F基因的RNAi载体p MHJ137,通过农杆菌介导的方法转化土曲霉F001,筛选整合到染色体的阳性菌,并在阳性菌株MJ1-24的发酵过程中加入了DMB-S-MMP验证其直接合成辛伐他汀的效率。结果显示MJ1-24不再产生洛伐他汀,产物中仅有莫那可林J累积。如果在发酵过程中加入前体物质,可得到产物辛伐他汀。综上,RNAi技术能够有效实现土曲霉基因沉默。此项技术推进了一步法发酵生产辛伐他汀的工艺开发。     

Exendin-4对成年小鼠脑室下区神经干细胞分化作用的体外研究*

目的:研究艾塞那肽(Ex-4)对成年小鼠脑室下区(SVZ)神经干细胞(NSCs)分化的影响及机制。方法:提取5周龄C57BL/6J小鼠SVZ的NSCs,100 nmol/L Ex-4处理分化14 d观察细胞形态,用免疫荧光检测巢蛋白(nestin)和胰高糖素样肽-1受体(GLP-1R)的表达。用shRNA敲低GLP-1R,将研究分为四组:对照组,Ex-4组,GLP-1R敲低组,GLP-1R敲低+Ex-4组。100 nmol/L Ex-4处理14 d后免疫荧光标记β-微管蛋白3(β-tublin III)和胶质纤维酸性蛋白(GFAP)并统计β-tublin III阳性细胞比例,Western blot检测环磷腺苷效应元件结合蛋白(CREB)的活化。为进一步研究Ex-4对MAPK和PI3K通路的影响,分别以丝裂原活化蛋白激酶(MAPK)抑制剂U0126 0.07 μmol/L预处理细胞30 min、磷脂酰肌醇-3激酶(PI3K)抑制剂LY294002 50 μmol/预处理细胞2 h,将研究分为: 对照组,Ex-4组,U0126组,U0126+Ex-4组,LY294002组,LY294002+Ex-4组,Western blot检测各组CREB的活化,各组实验独立重复三次。结果:成功从C57BL/6J小鼠SVZ提取NSCs,免疫荧光提示NSCs中nestin以及GLP-1R阳性。相对于对照组,Ex-4组分化为神经元的比例更高。GLP-1R敲低+Ex-4组中神经元比例与对照组基本一致(P＜0.01),β-tublin III阳性的细胞显示出GLP-1R以及CREB活化阳性。Western blot显示Ex-4组中CREB显著活化,GLP-1R敲低+Ex-4组的CERB活化与对照组基本一致(P＜0.01)。U0126+Ex-4组与Ex-4组CERB活化水平一致,LY294002+Ex-4组与对照组CERB活化水平一致(P＜0.01)。 结论:Ex-4通过GLP-1R受体促进成年小鼠SVZ中NSCs分化为神经元,这一作用可能通过PI3K/ CREB通路来实现。     

基于RAD-SNPs分析的四川核桃良种资源的遗传多样性研究

为了解四川核桃(Juglans)种质资源的遗传多样性,利用RAD二代测序技术对42份核桃良种资源进行测序,分析其遗传结构和遗传多样性。结果表明,共获得70G clean data,Q30平均为96.3%,并获得160 309个多态性SNPs。聚类、遗传结构和主成分分析结果高度一致,42份种质资源聚为两大类,基本反映了两个原始祖先血统,即普通核桃类(AJR,33份)和泡核桃类(AJS,9份),两类群具较高的遗传分化(FST=0.285),且分类与地理位置分布和种群相关;且修正了‘威薄01’、‘白龙1号’和‘石棉巨核’3个品种的类群认定。AJS和AJR类群中分别有9和14个良种为纯血统且亲缘关系较远,而其余的良种均为两个血统的混杂。42个核桃良种资源的核苷酸多样性[Pi(π)]和期望杂合度(He)分别为0.029和0.286,表明这些资源具有丰富的遗传多样性,相对于AJR类群,AJS类群的杂合率(He)与核苷酸多态性更大,而SNP数更少,AJS遗传多样性更丰富。这些为四川的核桃种质资源保存和杂交育种研究奠定了基础。     

Diphenyleneiodonium suppresses apoptosis in cerulein-stimulated pancreatic acinar cells

NADPH oxidase has been considered a major source of reactive oxygen species in phagocytic and non-phagocytic cells. Apoptosis linked to oxidative stress has been implicated in pancreatitis. Recently, we demonstrated that NADPH oxidase subunits Nox1, p27phox, p47phox, and p67phox are constitutively expressed in pancreatic acinar cells, which are activated by cerulein, a cholecystokinin analogue. Cerulein induces an acute and edematous form of pancreatitis. We investigated whether inhibition of NADPH oxidase by diphenyleneiodonium suppresses the production of reactive oxygen species and apoptosis by determining viable cell numbers, DNA fragmentation, TUNEL staining, caspase-3 activity, and the expression of apoptosis-inducing factor in pancreatic acinar AR42J cells stimulated with cerulein. Inhibition on NADPH oxidase by diphenyleneiodonium was assessed by the alterations in NADPH oxidase activity and translocation of the cytosolic subunits p67phox and p47phox to the membrane. Intracellular Ca2+ level was monitored to investigate the relationship between NADPH oxidase and Ca2+ in cells stimulated with cerulein. As a result, cerulein induced the activation of NADPH, increased production of reactive oxygen species, and apoptotic indices determined by the expression of apoptosis-inducing factor, caspase-3 activation, TUNEL staining, DNA fragmentation, and cell viability. Treatment with DPI inhibited cerulein-induced activation of NADPH oxidase, the production of reactive oxygen species, and apoptosis, but not the increase of intracellular Ca2+ levels in pancreatic acinar cells. These results demonstrate that the cerulein-induced increase in intracellular Ca2+ level may be an upstream event of NADPH oxidase activation. Diphenyleneiodonium, an NADPH oxidase inhibitor, inhibits the expression of apoptosis-inducing factor and caspase-3 activation, and thus apoptosis in pancreatic acinar cells.     

Overexpression of KCNJ4 correlates with cancer progression and unfavorable prognosis in lung adenocarcinoma

KCNJ4 (potassium voltage‐gated channel subfamily J member 4) belongs to the inward rectifier potassium channel family, which is inhibited by novel anticancer agents. However, the biologic significance of KCNJ4 in lung adenocarcinoma (LADC) is largely unknown. Therefore, in this study, we evaluated the expression, clinical correlation, and prognostic value of KCNJ4 in LADC and normal lung tissues according to data from The Cancer Genome Atlas datasets. A small interfering RNA (siRNA)‐mediated technology was used to inhibit the expression level of KCNJ4. Cell counting kit‐8 and plate colony formation assays were used to measure cell proliferation. Wound‐healing and transwell assays were applied to detect cell mobility and metastasis. Quantitative real‐time polymerase chain reaction and western blot analysis were used to examine messenger RNA and protein expressions, respectively. It was found that KCNJ4 was significantly upregulated in LADC tissues and cells. The high level of KCNJ4 predicted shorter overall survival and was identified as an independent prognostic factor in patients with LADC. siRNA‐mediated KCNJ4 silencing impeded LADC cell proliferation, migration, and invasion. Knockdown of KCNJ4 suppressed the expression of phosphorylated mitogen‐activated protein kinase/extracellular signal regulated kinase (p‐MEK) and phosphorylated extracellular signal‐regulated kinase (p‐ERK). Collectively, these results shed some light on the contribution of KCNJ4 functioning as a significant player in LADC, implying that KCNJ4 might be a valuable prognostic biomarker and a potential therapeutic target for LADC treatment.     

Deciphering the ‘Elixir of Life’: Dynamic Perspectives into the Allosteric Modulation of Mitochondrial ATP Synthase by J147, a Novel Drug in the Treatment of Alzheimer's Disease

The discovery of J147 represented a significant milestone in the treatment of age‐related disorders, which was further augmented by the recent identification of mitochondrial ATP synthase as the therapeutic target. However, the underlying molecular events associated with the modulatory activity of J147 have remained unresolved till date. Herein, we present, for the first time, a dynamical approach to investigate the allosteric regulation of mATP synthase by J147, using a reliable human αγβ protein model. The highlight of our findings is the existence of the J147‐bound protein in distinct structural associations at different MD simulation periods coupled with concurrent open?close transitions of the β catalytic and α allosteric (ATP5A) sites as defined by Cα distances (d), TriCα (Θ) and dihedral (φ) angular parameters. Firstly, there was an initial pairing of the αγ subunits away from the β subunit followed by the formation of the ‘non‐catalytic’ αβ pair at a distance from the γ subunit. Interestingly, J147‐induced structural arrangements were accompanied by the systematic transition of the β catalytic site from a closed to an open state, while there was a concurrent transition of the allosteric site from an open α_E conformation to a closed state. Consequentially, J147 reduced the structural activity of the whole αγβ complex, while the unbound system exhibited high atomistic deviations and structural flexibility. Furthermore, J147 exhibited favorable binding at the allosteric site of mATP synthase with considerable electrostatic energy contributions from Gln215, Gly217, Thr219, Asp312, Asp313, Glu371 and Arg406. These findings provide details on the possible effects of J147 on mitochondrial bioenergetics, which could facilitate the structure‐based design of novel small‐molecule modulators of mATP synthase in the management of Alzheimer's disease and other neurodegenerative disorders.     

Trace metal uptake in liver cells: 1. Influence of albumin in the medium on the uptake of copper by hepatoma cells

Cultured rat hepatoma cells (HTC-cells) were used to study the transfer of copper from a well-defined medium to and across the cell membrane and particularly the role of albumin in this process. HTC-cells, maintained in a minimal salt-glucose medium, accumulated far more copper than when maintained in the same medium, but supplemented with albumin. In the latter case, the Cu uptake strongly depended on the molar Cu/albumin ratio. The results suggest a role of albumin in the uptake of trace metals. The results indicate the presence of two types of binding sites for copper on the cell membrane. The sites of the first type bind copper very strongly and are probably responsible for the uptake of copper under physiological conditions. Their number was estimated to be about 10⁶ per cell. Those of the second type only bind copper when the molar Cu/albumin ratio exceeds a value of about 1, i.e., under extreme, unphysiological conditions. Furthermore, the results suggest a direct interaction of the Cu-albumin complex with these strong binding sites as a first step in Cu uptake processes.