Regulation of ion channels by protein tyrosine phosphorylation

Ion channels are regulated by protein phosphorylation and dephosphorylation of serine, threonine, and tyrosine residues. Evidence for the latter process, tyrosine phosphorylation, has increased substantially since this topic was last reviewed. In this review, we present a comprehensive summary and synthesis of the literature regarding the mechanism and function of ion channel regulation by protein tyrosine kinases and phosphatases. Coverage includes the majority of voltage-gated, ligand-gated, and second messenger-gated channels as well as several types of channels that have not yet been cloned, including store-operated Ca2+ channels, nonselective cation channels, and epithelial Na+ and Cl- channels. Additionally, we discuss the critical roles that channel-associated scaffolding proteins may play in localizing protein tyrosine kinases and phosphatases to the vicinity of ion channels.     

Interleukin-1beta, Src- and non-Src tyrosine kinases, and nitric oxide synthase induction in rat aorta in vitro

We studied the potential roles for endogenous interleukin-1beta (IL-1beta) and for several signaling pathways in the spontaneous induction in vitro of inducible nitric oxide synthase (iNOS) in endothelium-denuded rat aorta rings. Added IL-1beta augmented, whereas the IL-1beta receptor antagonist IL-1ra blocked, spontaneous iNOS induction. Furthermore, increases in IL-1beta mRNA preceded those of iNOS mRNA. Mitogen-activated protein kinase kinase and phosphatidyl inositol 3' kinase inhibition did not block iNOS induction, whereas nuclear factor kappaB inhibition did. The sarcoma virus tyrosine kinase (Src) family-selective inhibitor 4-amino-5(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP1) blocked the upregulation of IL-1beta mRNA and the subsequent induction of iNOS but not the induction of iNOS stimulated by exogenously added IL-1beta. In contrast, the non-Src inhibitors TP 47/AG 213 and genistein and the tyrosine phosphatase inhibitor vanadate did not affect the spontaneous upregulation of IL-1beta mRNA but blocked both the IL-1beta-mediated and spontaneous induction of iNOS. We conclude that 1) the upregulation of tissue IL-1beta, via a signaling pathway involving a Src family kinase, plays a key role in rat vascular iNOS induction and 2) non-Src tyrosine kinases play roles downstream from IL-1beta for iNOS induction.     

银鲫复合种外源遗传物质整入的RAPD分析

在优化ＲＡＤＰＤ检测条件的基础上,采用４０对随机引物,比较分析了银复合物,异育银鲫和兴国红鲤相互间扩增ＤＮＡ片段的异同性。总的来说,银鲫复合种和异育银鲫具有基本一致的扩增产物,而与兴国红鲤的扩增产物多数不同,相似率分析表明,银鲫复合种与兴国红鲤之间的相似率为３１．６％,异育银鲫与兴国红鲤之间的相似率为２８．６％。在分析中,除发现银鲫复合种,异育银鲫与兴国红鲤间共有扩增片段外,还发现了银鲫复合种与兴     

人血小板生成素氨基端功能区cDNA的克隆及其定点突变

以Nested－PCR方法从人肝cDNA基因文库中扩增出编码人血小板生成素（hTPO）前153个氨基酸的氨基端功能区cDNA;在扩增中,采用非连续多核甘酸定点突变的方法．将翻译起始的七个氨基酸的原核中不常用的密码子同又突变成使用频率较高的密码子,以便于其在大肠杆菌中表达。序列测定证实了预期的结果。     

维甲酸对鼻咽癌细胞生长、表型和瘤基因表达的作用

研究了维甲酸（ＲＡ）对鼻咽癌细胞生长、表型和癌基因表达的作用．用ＲＡ诱导鼻咽癌细胞,绘制诱导前后的细胞曲线,观察细胞形态,并用Ｎｏｒｔｈｅｒｎ杂交和ＤＮａｓｅⅠ超敏感区分析法检测基因表达和调控．结果表明,ＲＡ能显著抑制鼻咽癌细胞的生长,前５ｄ下降约５０％．ＲＡ处理后的细胞从典型的多边形形态变成扁平、细长,类似纤维细胞状的形态．ＲＡ诱导前ｃ－ｍｙｃ基因和ｃ－Ｈａ－ｒａｓ基因ＨＮＥ２细胞中高表达,而诱导后ｃ－ｍｙｃ基因表达水平急剧下降,ｃ－Ｈａ－ｒａｓ基因无明显改变．在实验中还发现ＲＡ诱导前后的ｃ－ｍｙｃ基因和ｃ－Ｈａ－ｒａｓ基因中一些重要的超敏感位点和它们的功能．由实验结果可得到如下结论：ＲＡ能促进鼻咽癌细胞分化,通过对染色体上调控位点的作用来抑制ｃ－ｍｙｃ基因的表达,ＤＮａｓｅⅠ超敏感位点与细胞的分化程度、细胞的组织特异性和基因表达状态有关,ｃ－ｍｙｃ基因可通过不同的调控方式而失活．     

家兔胚胎细胞核移植的研究(英文)

本研究以兔为实验材料,对细胞核移植过程中显微操作、电融合、电活化以及移核胚的培养等基本问题进行了研究。对兔进行ＰＭＳＧｈＣＧ超数排卵,收集成熟卵母细胞和１６细胞胚;后者经胰蛋白酶消化,去除胶膜和透明带,在不含Ｃａ２＋、Ｍｇ２＋的分离液中分成单个卵裂球;然后,分别对两者做ＣＢ预处理;首次尝试采用Ｗｉｌａｄｓｅｎ法,去除卵母细胞核、并将单个卵裂球注入透明带,同时、与ＭｃＧｒａｔｈＳｏｌｔｅｒ法进行比较;通过电融合使供体核进入去核的卵母细胞内;将所得移核胚在体外或在中间受体内培养并观察。结果表明：一、Ｗｉｌａｄｓｅｎ法与ＭｃＧｒａｔｈＳｏｌｔｅｒ法比较,核移植操作的成功率及以后的电融合率均无明显差异（Ｔａｂ．１）。相对于后者,Ｗｉｌａｄｓｅｎ法更简便、易于掌握并提高去核率。二、ｈＣＧ超排注射后１３～１５ｈ,观察卵母细胞发现：其中,６７８％保留有第一极体。此时的卵子若去除１／３胞质量,去核率可以达到５８３％。若推迟去核时间,笫一极体退化,失去去核标志。三、比较不同电脉冲条件,发现强度为０６３ｋｖ／ｃｍ,持续１６０μｓ的一次电脉冲可获较高移核胚的融合率（７０．８％）（Ｔａｂ．２）;并可使６１１％的成熟     

Lupane‐ and Friedelane‐Type Triterpenoids from Celastrus stylosus

Two new triterpenoids, 30‐hydroxylup‐20(29)‐ene 3β‐caffeate ( 1 ) and 24‐nor‐friedelan‐6α,10‐dihydroxy‐1,2‐dioxo‐4,7‐dien‐29‐oic acid ( 2 ), together with eight known compounds 3 – 10 , were isolated from the roots of Celastrus stylosus. The structures of these compounds were elucidated on the basis of spectroscopic analyses. To the best of our knowledge, this represents the first study on the chemical constituents of C. stylosus. The antiproliferative activities of the triterpenoids against six human cancer cell lines (PANC‐1, A549, PC‐3, HepG2, SGC‐7901, and HCCLM3) were evaluated. Compounds 3, 4 , and 10 exhibited comparable activities against PC‐3 and HCCLM3 cell lines as the positive control taxol.     

Glucose alleviates cadmium toxicity by increasing cadmium fixation in root cell wall and sequestration into vacuole in Arabidopsis

Glucose(Glu) is involved in not only plant physiological and developmental events but also plant responses to abiotic stresses. Here, we found that the exogenous Glu improved root and shoot growth, reduced shoot cadmium(Cd) concentration, and rescued Cdinduced chlorosis in Arabidopsis thaliana(Columbia ecotype,Col-0) under Cd stressed conditions. Glucose increased Cd retained in the roots, thus reducing its translocation from root to shoot signi fi cantly. The most Cd retained in the roots was found in the hemicellulose 1. Glucose combined with Cd(Glu t Cd) treatment did not affect the content of pectin and its binding capacity of Cd while it increased the content of hemicelluloses 1 and the amount of Cd retained in it signi fi cantly. Furthermore, Leadmium Green staining indicated that more Cd was compartmented into vacuoles in Glu t Cd treatment compared with Cd treatment alone, which was in accordance with the R e ssigni fi cant upregulation of the expression of tonoplastlocalized metal transporter genes, suggesting that compartmentation of Cd into vacuoles also contributes to the Glu-alleviated Cd toxicity. Taken together, we demonstrated that Glu-alleviated Cd toxicity is mediated through increasing Cd fi xation in the root cell wall and sequestration into the vacuoles.