Structural mechanism for STI-571 inhibition of abelson tyrosine kinase

The inadvertent activation of the Abelson tyrosine kinase (Abl) causes chronic myelogenous leukemia (CML). A small-molecule inhibitor of Abl (STI-571) is effective in the treatment of CML. We report the crystal structure of the catalytic domain of Abl, complexed to a variant of STI-571. Critical to the binding of STI-571 is the adoption by the kinase of an inactive conformation, in which a centrally located "activation loop" is not phosphorylated. The conformation of this loop is distinct from that in active protein kinases, as well as in the inactive form of the closely related Src kinases. These results suggest that compounds that exploit the distinctive inactivation mechanisms of individual protein kinases can achieve both high affinity and high specificity.     

Selective inhibition of leukemia cell proliferation by BCR-ABL antisense oligodeoxynucleotides

To determine the role of the BCR-ABL gene in the proliferation of blast cells of patients with chronic myelogenous leukemia, leukemia blast cells were exposed to synthetic 18-mer oligodeoxynucleotides complementary to two identified BCR-ABL junctions. Leukemia colony formation was suppressed, whereas granulocyte-macrophage colony formation from normal marrow progenitors was unaffected. When equal proportions of normal marrow progenitors and blast cells were mixed, exposed to the oligodeoxynucleotides, and assayed for residual colony formation, the majority of residual cells were normal. These findings demonstrate the requirement for a functional BCR-ABL gene in maintaining the leukemic phenotype and the feasibility of gene-targeted selective killing of neoplastic cells.     

Bypassing a kinase activity with an ATP-competitive drug

Unfolded proteins in the endoplasmic reticulum cause trans-autophosphorylation of the bifunctional transmembrane kinase Ire1, which induces its endoribonuclease activity. The endoribonuclease initiates nonconventional splicing of HAC1 messenger RNA to trigger the unfolded-protein response (UPR). We explored the role of Ire1's kinase domain by sensitizing it through site-directed mutagenesis to the ATP-competitive inhibitor 1NM-PP1. Paradoxically, rather than being inhibited by 1NM-PP1, drug-sensitized Ire1 mutants required 1NM-PP1 as a cofactor for activation. In the presence of 1NM-PP1, drug-sensitized Ire1 bypassed mutations that inactivate its kinase activity and induced a full UPR. Thus, rather than through phosphorylation per se, a conformational change in the kinase domain triggered by occupancy of the active site with a ligand leads to activation of all known downstream functions.     

蛋白激酶C抑制剂对CNE—2Z细胞周期的影响

目的：蛋白激酶Ｃ（ＰＫＣ）抑制剂诱导ＣＮＥ－２Ｚ细胞凋亡时细胞周期的观察。方法：ＰＫＣ催化区抑制剂Ｓｔａｕｒｏｓｐｏｉｎｅ（ＳＴ）和调节区抑制剂Ｓｐｈｉｎｇｏｓｉｎｅ（ＳＳ），终浓度分别为１×１０＾－６ｍｏｌ／Ｌ和４×１０＾－５ｍｏｌ／Ｌ，诱导ＣＮＥ－２Ｚ细胞２４ｈ，用流式细胞仪（ＲＣＭ）分析。结果：诱导组细胞周期与对照组比较，ＳＴ使细胞Ｇ１和Ｓ期明显减少及Ｇ２期明显增加，（Ｐ〈０．０１），ＳＳ使     

Inhibition of postsynaptic PKC or CaMKII blocks induction but not expression of LTP

Long-term potentiation (LTP) of synaptic transmission is a widely studied cellular example of synaptic plasticity. However, the identity, localization, and interplay among the biochemical signals underlying LTP remain unclear. Intracellular microelectrodes have been used to record synaptic potentials and deliver protein kinase inhibitors to postsynaptic CA1 pyramidal cells. Induction of LTP is blocked by intracellular delivery of H-7, a general protein kinase inhibitor, or PKC(19-31), a selective protein kinase C (PKC) inhibitor, or CaMKII(273-302), a selective inhibitor of the multifunctional Ca2+-calmodulin-dependent protein kinase (CaMKII). After its establishment, LTP appears unresponsive to postsynaptic H-7, although it remains sensitive to externally applied H-7. Thus both postsynaptic PKC and CaMKII are required for the induction of LTP and a presynaptic protein kinase appears to be necessary for the expression of LTP.     

Regulation of a cyclin-CDK-CDK inhibitor complex by inositol pyrophosphates

In budding yeast, phosphate starvation triggers inhibition of the Pho80-Pho85 cyclin-cyclin-dependent kinase (CDK) complex by the CDK inhibitor Pho81, leading to expression of genes involved in nutrient homeostasis. We isolated myo-d-inositol heptakisphosphate (IP7) as a cellular component that stimulates Pho81-dependent inhibition of Pho80-Pho85. IP7 is necessary for Pho81-dependent inhibition of Pho80-Pho85 in vitro. Moreover, intracellular concentrations of IP7 increased upon phosphate starvation, and yeast mutants defective in IP7 production failed to inhibit Pho80-Pho85 in response to phosphate starvation. These observations reveal regulation of a cyclin-CDK complex by a metabolite and suggest that a complex metabolic network mediates signaling of phosphate availability.     

Structural bioinformatics-based design of selective, irreversible kinase inhibitors

The active sites of 491 human protein kinase domains are highly conserved, which makes the design of selective inhibitors a formidable challenge. We used a structural bioinformatics approach to identify two selectivity filters, a threonine and a cysteine, at defined positions in the active site of p90 ribosomal protein S6 kinase (RSK). A fluoromethylketone inhibitor, designed to exploit both selectivity filters, potently and selectively inactivated RSK1 and RSK2 in mammalian cells. Kinases with only one selectivity filter were resistant to the inhibitor, yet they became sensitized after genetic introduction of the second selectivity filter. Thus, two amino acids that distinguish RSK from other protein kinases are sufficient to confer inhibitor sensitivity.     

A conserved p38 MAP kinase pathway in Caenorhabditis elegans innate immunity

A genetic screen for Caenorhabditis elegans mutants with enhanced susceptibility to killing by Pseudomonas aeruginosa led to the identification of two genes required for pathogen resistance: sek-1, which encodes a mitogen-activated protein (MAP) kinase kinase, and nsy-1, which encodes a MAP kinase kinase kinase. RNA interference assays and biochemical analysis established that a p38 ortholog, pmk-1, functions as the downstream MAP kinase required for pathogen defense. These data suggest that this MAP kinase signaling cassette represents an ancient feature of innate immune responses in evolutionarily diverse species.     

蛋白激酶C抑制剂对吸烟大鼠脑血管内皮细胞细胞间粘附分子1表达的影响

目的探讨蛋白激酶C抑制剂对吸烟大鼠脑血管内皮细胞细胞间粘附分子1蛋白和mRNA表达的影响。方法无脑梗死大鼠18只,随机分为不吸烟组6只、吸烟组6只和吸烟蛋白激酶C抑制剂组6只。脑梗死大鼠48只,随机分为脑梗死组24只和蛋白激酶C抑制剂组24只,分别于梗死后2、6、12及24h干预,每个时间点6只。采用免疫组织化学法和原位杂交法分别测定细胞间粘附分子1蛋白和mRNA。结果吸烟大鼠脑血管内皮细胞细胞间粘附分子1蛋白和mRNA均有表达,吸烟蛋白激酶C抑制剂组脑血管内皮细胞细胞间粘附分子1蛋白和mRNA的表达明显低于吸烟组(P<0.05)。蛋白激酶C抑制剂组细胞间粘附分子1蛋白和mRNA的表达均低于对应时间点脑梗死组(P<0.05),且梗死后2h蛋白激酶C抑制剂组细胞间粘附分子1蛋白和mRNA的表达明显低于其他时间点组。结论蛋白激酶C抑制剂可阻断吸烟大鼠脑血管内皮细胞细胞间粘附分子1蛋白和mRNA表达,并且早期用药效果可能更好。     

大气边界层理论及其在小麦白粉病流行研究中的应用

本文讨论了大气边界理论及其与病原菌远距离传输的关系。包括大气边界层一般概念，大气边界层内的气流方向，病原菌分生孢子进入大气层的动力，分生孢子的远程输送与沉降。此外，还以小麦白粉病为例，分析验证了大气边界层理论在植病流行学研究中应用的前景。     

ROCK选择性抑制剂Y-27632提高小鼠胚胎干细胞传代效率研究

以小鼠胚胎干细胞(ES细胞)为研究对象,探讨ROCK选择性抑制剂Y-27632在细胞传代过程中的作用,并对ES细胞相关生物学特性进行检测。结果表明:Y-27632能够引起ES细胞形态发生改变,通过Y-27632的添加能够使质地紧密的ES细胞集落变得松散、扁平。将Y-27632应用于ES细胞传代,能够显著提高传代效率。并且,在Y-27632长期存在的条件下,ES细胞依旧维持稳定的染色体数目,较强的碱性磷酸酶活性,在体内能够分化形成畸胎瘤,在体外能够分化形成心肌细胞。说明Y-27632的使用能够显著提高小鼠ES细胞的传代效率;紧密的细胞连接不是维持ES细胞多能性的必要条件。     

Fork reversal and ssDNA accumulation at stalled replication forks owing to checkpoint defects

Checkpoint-mediated control of replicating chromosomes is essential for preventing cancer. In yeast, Rad53 kinase protects stalled replication forks from pathological rearrangements. To characterize the mechanisms controlling fork integrity, we analyzed replication intermediates formed in response to replication blocks using electron microscopy. At the forks, wild-type cells accumulate short single-stranded regions, which likely causes checkpoint activation, whereas rad53 mutants exhibit extensive single-stranded gaps and hemi-replicated intermediates, consistent with a lagging-strand synthesis defect. Further, rad53 cells accumulate Holliday junctions through fork reversal. We speculate that, in checkpoint mutants, abnormal replication intermediates begin to form because of uncoordinated replication and are further processed by unscheduled recombination pathways, causing genome instability.     

雷州半岛桉树不同品种和树龄对磷吸收的影响

 研究雷州半岛2种主要桉树品种刚果12W₅（Eucalyptus ABL 12）和尾叶桉U6（Eucalyptus grandis U6）不同树龄不同部位对磷素养分的吸收特征和年际磷需求量。结果表明：1年生刚果12W₅和尾叶桉U6磷质量分数没有显著差异,但是1年生后植株磷质量分数前者显著低于后者;幼龄期时磷素主要分布在叶和枝中,随树龄增加树干、树皮和根中磷素有增加的趋势;磷素对不同树龄的桉树干物质积累量有显著影响,2种桉树的干物质量均为树干最大,树叶最小,各器官干物质量排序为：干＞根＞枝＞皮＞叶;从磷效率来看,单位质量磷对刚果12W₅干物质量的积累量比对尾叶桉U6干物质量的积累更加显著,表明刚果12W5对磷素需求低于尾叶桉U6。因此,在桉树生产中应注意因树种、因树龄进行磷素的施肥与管理。图4参12     

Cell mediated immunity: separation of cells involved in recognitive and destructive phases

The mixed leukocyte culture (MLC) and the cell mediated lympholysis (CML) assays are used as in vitro models of the afferent, or recognitive, and efferent, or destructive, phases of the homograft reaction. Activity in both of these tests has been related to differences at the major histocompatibility complex, HL-A in man and H-2 in mouse. Recent evidence suggests that the presumed cell surface differences which lead to cell proliferation in MLC are different from those which act as a target for CML. Data are presented providing further support for this hypothesis; in addition separate cell populations may respond to the differences which activate cells in MLC and to the differences which serve as targets for CML. There thus appears to be a dichotomy both for genetic control of, and cell populations involved in, the recognitive and destructive phases of cell mediated immunity.     

大麦CIPK基因家族鉴定及表达分析

钙调神经磷酸酶B样相互作用蛋白激酶(CIPK)蛋白家族是由Ca2+介导的植物信号通路中的关键蛋白家族,在植物抗逆和生长发育中起关键作用。本研究将生物信息学方法和转录组数据分析相结合,挖掘出大麦31个HvCIPK基因家族成员并将其分为5个亚家族。HvCIPKs基因家族成员具有CIPKs典型的N端激酶结构域和C端NAF调节结构域;蛋白质分子量在40302.27~89926.43KDa之间,为亲水性蛋白;启动子总共包含11种与非生物胁迫、激素调控以及生长发育相关的顺式作用元件;蛋白互作网络预测结果显示,HvCIPKs与Na+、K+转运体、ABA信号通路关键蛋白(SOS1、AKT1和ABL2)存在相互作用关系;转录组数据分析发现HvCIPK1、HvCIPK2、HvCIPK6、HvCIPK9、HvCIPK11受盐碱胁迫的诱导表达。该研究为进一步探索大麦HvCIPKs基因家族功能及调控机制提供理论依据。     

24个优质蛋白玉米自交系与中国温带玉米四大优势群代表自交系的配合力和杂种优势群研究

 【目的】研究QPM种质与中国温带种质之间的杂种优势关系并划分杂种优势群。【方法】采用NCⅡ设计对24个热带、亚热带优质蛋白玉米（QPM）自交系和4个温带普通玉米优良自交系配制96个杂交组合，在云南省3种不同生态环境下对这些杂交组合进行农艺性状和产量配合力分析，评价群体的应用价值和利用潜力，再根据产量特殊配合力效应和系谱追踪划分杂种优势群。【结果】自交系YML761、CML171、CML172、中系096/o2、YML411、YML024和YML042产量一般配合力较高。产量SCA效应较高的组合有YML401×黄早四、CML172×Mo17、YML761×掖478、长709/o2×Mo17、H152×丹340、中系096/o2×掖478和YML872×Mo17。【结论】自交系YML761、CML171、CML172、中系096/o2、YML411、YML024和YML042在生产中有较大的利用价值。YML411、YML042、CA307、YML065和YML401归入Lancaster群；CML165、CML166、YML761、中系096/o2、长631/o2、YML011、YML872归入旅大红骨群；CML171、CML161、CML172、齐205、CA10139、YML330、8129归入四平头群，CML163、CML170、H152、长709/o2和YML024归入Reid群。本研究结果与系谱分析及前人的研究基本一致。