代谢性谷氨酸受体配体(s)-4C3HPG对大鼠脑缺血耐受性诱导的影响

目的：观察侧脑室注射代谢型谷氨酸受体1／5亚型（mGluR1/5)配体（s)-4C3HPG对海马脑缺血耐受（BIT）诱导的影响,以探讨mGLUR1/5在BIT诱导中的作用。方法：采用大鼠四血管闭塞全脑缺血模型（4－vessel occlusion,4VO),应用硫堇染色和GFAP免疫组化法。36只大鼠椎动脉凝闭后分为sham组、单纯缺血组、BIT组和（s)-4C3HPG组,其中（s)-4C3HPG组又按所给药物剂量不同,分为0．2、0．04和0．008mg三个亚组。所有动物均在手术后或末次缺血后7d处死取材观察。结果：（1）单纯8min缺血可使海马CA1区组织学分级升高、锥体神经元密度降低和胶质纤维酸性蛋白（glial fibrillary acidic protein,GFAP)阳性表达增加（P＜0．05vs sham）.(2)BIT组未见单纯缺血组的上述变化,表明CIP可防止后续8min缺血造成的神经元损伤。（3）CIP的这种保护作用可被（s)-4C3HPG阻断,表现为海马CA1区组织学分级升高和锥体神经元密度降低（P＜0．05 vs sham)。这种变化与（s)-4C3HPG的剂量呈现明显的相关性,即剂量越大,上述改变越明显。结论：（s)-4C3HPG可阻断CIP诱导BIT的作用,提示mGluR1/5参与BIT的诱导。     

GnRH-II analogs for selective activation and inhibition of non-mammalian and type-II mammalian GnRH receptors

Recently, we identified three types of non-mammalian gonadotropin-releasing hormone receptors (GnRHR) in the bullfrog (designated bfGnRHR-1-3), and a mammalian type-II GnRHR in green monkey cell lines (denoted gmGnRHR-2). All these receptors responded better to GnRH-II than GnRH-I, while mammalian type-I GnRHR showed greater sensitivity to GnRH-I than GnRH-II. In the present study, we designed new GnRH-II analogs and examined whether they activated or inhibited non-mammalian and mammalian type-II GnRHRs. [D-Ala6]GnRH-II, with D-Ala substituted for Gly6 in GnRH-II, increased inositol phosphate (IP) production in cells stably expressing non-mammalian GnRHRs more effectively than native GnRH-II. However, it exhibited lower activity for mammalian type-I GnRHR than GnRH-I itself. Trptorelix-1, a GnRH-II antagonist, inhibited GnRH-induced IP production in cells expressing non-mammalian GnRHRs more effectively than Cetrorelix, a GnRH-I antagonist. Trptorelix-1, however, had lower potency for mammalian type-I GnRHR than Cetrorelix. Ligand-receptor binding assays revealed that [D-Ala6]GnRH-II and Trptorelix-1 have higher affinities for non-mammalian GnRHRs but lower affinities for mammalian type-I GnRHR than GnRH-II and Cetrorelix, respectively. Moreover, [D-Ala6]GnRH-II and Trptorelix-1 had a higher affinity for gmGnRHR-2 than GnRH-II and Cetrorelix, respectively. These results indicate that [D-Ala6]GnRH-II and Trptorelix-1 are highly effective agonist and antagonist, respectively, for non-mammalian and type-II mammalian GnRHRs.     

QSulf1 remodels the 6-O sulfation states of cell surface heparan sulfate proteoglycans to promote Wnt signaling

The 6-O sulfation states of cell surface heparan sulfate proteoglycans (HSPGs) are dynamically regulated to control the growth and specification of embryonic progenitor lineages. However, mechanisms for regulation of HSPG sulfation have been unknown. Here, we report on the biochemical and Wnt signaling activities of QSulf1, a novel cell surface sulfatase. Biochemical studies establish that QSulf1 is a heparan sulfate (HS) 6-O endosulfatase with preference, in particular, toward trisulfated IdoA2S-GlcNS6S disaccharide units within HS chains. In cells, QSulf1 can function cell autonomously to remodel the sulfation of cell surface HS and promote Wnt signaling when localized either on the cell surface or in the Golgi apparatus. QSulf1 6-O desulfation reduces XWnt binding to heparin and HS chains of Glypican1, whereas heparin binds with high affinity to XWnt8 and inhibits Wnt signaling. CHO cells mutant for HS biosynthesis are defective in Wnt-dependent Frizzled receptor activation, establishing that HS is required for Frizzled receptor function. Together, these findings suggest a two-state "catch or present" model for QSulf1 regulation of Wnt signaling in which QSulf1 removes 6-O sulfates from HS chains to promote the formation of low affinity HS-Wnt complexes that can functionally interact with Frizzled receptors to initiate Wnt signal transduction.     

Low-temperature-induced structural changes in human lysozyme elucidated by three-dimensional NMR spectroscopy

The three-dimensional solution structures of human lysozyme were determined at 35 and 4 degrees C using the heteronuclear multidimensional NMR spectroscopy, which were compared with each other to clarify the structural response of this enzyme to lowering of the temperature. Together with the data of the temperature dependence experiments of the lytic activity against Micrococcus luteus, we consider the implication of the observed structural change for the low-temperature-induced reduction of the activity of human lysozyme. The structures of human lysozyme determined at the two temperatures are found to be similar, both of which comprise four alpha-helices (A- to D-helices) and three antiparallel beta-strands (beta(1)-beta(3)), leading to the constructions of the alpha- and beta-domains as previously identified in the X-ray crystal structure. A significant structural change was observed for the "active site lobe" comprising the loop region connecting C- and D-helices and the following D-helix, which moves toward the active site cleft located between the alpha- and beta-domains so as to obstruct the cleft according to the temperature lowering. It further appeared that the total volume as well as the accessible surface area of human lysozyme decreases with lowering of the temperature, suggesting that the internal cavity of this enzyme shrinks under low temperature environment. Because in human lysozyme the region comprising the active site lobe is responsible for turnover of the enzymatic reaction against the substrate, the low-temperature-induced structural change of the active site lobe presumably controls the efficiency of the lytic activity under low temperatures.     

Two lignan dimers from bamboo stems (Phyllostachys edulis)

Phyllostadimers A and B, two bis-lignans in which the two lignan units are directly connected by a C-C bond, were isolated from stems of bamboo, Phyllostachys edulis. Their structures were determined on the basis of spectral evidence. In addition, 14 known compounds were also obtained throughout the investigation. Phyllostadimer A significantly inhibited liposomal lipid peroxidation.     

Distal recognition site for classical pathway convertase located in the C345C/netrin module of complement component C5

Previous studies focused on indels in the complement C345 protein family identified a number of potential protein-protein interaction sites in components C3 and C5. Here, one of these sites in C5, near the alpha-chain C terminus, was examined by alanine-scanning mutagenesis at 16 of the 18 non-alanine residues in the sequence KEALQIKYNFSF RYIYPLD. Alanine substitutions affected activities in the highly variable manner characteristic of binding sites. Substitutions at the lysine or either phenylalanine residue in the central KYNFSF sequence had the greatest effects, yielding mutants with <20% of the normal activity. These three mutants were also resistant to the classical pathway (CP) C5 convertase, with sensitivities roughly proportional to their hemolytic activities, but had normal susceptibilities to the cobra venom factor (CVF)-dependent convertase. Synthetic peptide MGKEALQIKYNFS-NH2 was found similarly to inhibit CP but not CVF convertase activation, and the effects of alanine substitutions in this peptide largely reflected those of the equivalent mutations in C5. These results indicate that residues KYNFSF form a novel, distal binding site for the CP, but not CVF convertase. This site lies approximately 880 residues downstream of the convertase cleavage site within a module that has been independently named C345C and NTR; this module is found in diverse proteins including netrins and tissue inhibitors of metalloproteinases.     

豌豆中可与Gro EL抗体发生免疫学反应的热激诱导蛋白

通过Ｗｅｓｔｅｒｎ印渍方法,发现在豌豆（ＰｉｓｕｍｓａｔｉｖｕｍＬ．）叶存在一种高分子量的蛋白可与ＧｒｏＥＬ抗体发生免疫学反应,它含有两种亚基,分子量分别为６０．４ｋＤ（α）和６５．５ｋＤ（β）,具有弱的ＡＴＰａｓｅ活性。热激处理后此蛋白的表达升高３～４倍,但外源ＡＢＡ处理并不增加它的表达。用３５Ｓ标记蛋白和氯霉素抑制实验表明,此蛋白可能是在８０Ｓ核糖体上合成的胞质蛋白。     

动脉内灌药,内支架安置双介入治疗十二指肠恶性梗阻

通过动脉内灌药,内支架安置双介入治疗提高对十二指肠恶性梗阻姑息性治疗的疗效。十二指肠恶性梗阻病例１４例,男５例,女９例,年龄２０－６９岁,经口安置自膨式十二指肠金属支架共１５枚,其中１２例在支架安置后定期行肿瘤供血动脉插管介入化疗,所有病例梗阻症状解除,２例未行动脉灌药治疗者分别于２个月及４个月死亡,１２例双介入者生存期明显延长,最短６月,最长已达一年,结论：双介入治疗能够姑息治疗疗效延长晚期瘤患     

ITMSQ: A software tool for N‐ and C‐terminal fragment ion pairs based isobaric tandem mass spectrometry quantification

Tandem MS (MS2) quantification using the series of N‐ and C‐terminal fragment ion pairs generated from isobaric‐labelled peptides was recently considered an accurate strategy in quantitative proteomics. However, the presence of multiplexed terminal fragment ion in MS2 spectra may reduce the efficiency of peptide identification, resulting in lower identification scores or even incorrect assignments. To address this issue, we developed a quantitative software tool, denoted isobaric tandem MS quantification (ITMSQ), to improve N‐ and C‐terminal fragment ion pairs based isobaric MS2 quantification. A spectrum splitting module was designed to separate the MS2 spectra from different samples, increasing the accuracy of both identification and quantification. ITMSQ offers a convenient interface through which parameters can be changed along with the labelling method, and the result files and all of the intermediate files can be exported. We performed an analysis of in vivo terminal amino acid labelling labelled HeLa samples and found that the numbers of quantified proteins and peptides increased by 13.64 and 27.52% after spectrum splitting, respectively. In conclusion, ITMSQ provides an accurate and reliable quantitative solutionfor N‐ and C‐terminal fragment ion pairs based isobaric MS2 quantitative methods.