Role of c-Abl in the DNA damage stress response

c-Abl has been implicated in many cellular processes including differentiation, division, adhesion, death, and stress response, c-Abl is a latent tyrosine kinase that becomes activated in response to numerous extra- and intra-cellular stimuli. Here we briefly review the current knowledge about c-Abl involvement in the DNA-damage stress response and its implication on cell physiology.     

WNK1： analysis of protein kinase structure, downstream targets, and potential roles in hypertension

The WNK kinases are a recently discovered family of serine-threonine kinases that have been shown to play an essential role in the regulation of electrolyte homeostasis, lntronic deletions in the WNK1 gene resuk in its overexpression and lead to pseudohypoaldosteronism type Ⅱ, a disease with salt-sensitive hypertension and hyperkalemia. This review focuses on the recent evidence elucidating the structure of the kinase domain of WNK1 and functions of these kinases in normal and disease physiology. Their functions have implications for understanding the biochemical mechanism that could lead to the retention or insertion of proteins in the plasma membrane. The WNK kinases may be able to influence ion homeostasis through its effects on synaptotagmin function.     

Prolonged Alzheimer-like tau hyperphosphorylation induced by simultaneous inhibition of phosphoinositol-3 kinase and protein kinase C in N2a cells

Co-injection of wortmannin (inhibitor of phosphatidylinositol-3 kinase, PI3K) and GF109203X(inhibitor of protein kinase C, PKC) into the rat brain was found to induce spatial memory deficiency and enhance tau hyperphosphorylation in the hippocampus of rat brain. To establish a cell model with durative Alzheimer-like tau hyperphosphorylation in this study, we treated N2a neuroblastoma cells with wortmannin and GF109203X separately and simultaneously, and measured the glycogen synthase kinase 3 (GSK-3)activity by y-32p-labeling and the level of tau phosphorylation by Western blotting. It was found that the application of wortmannin alone only transitorily increased the activity of GSK-3 (about 1 h) and the level of tau hyperphosphorylation at Ser^396/Ser^404 and Ser^199/Ser^202 sites (no longer than 3 h); however, a prolonged and intense activation of GSK-3 (over 12 h) and enhanced tau hyperphosphorylation (about 24 h) were observed when these two selective kinase inhibitors were applied together. We conclude that the simultaneous inhibition of PI3K and PKC can induce GSK-3 overactivation, and further strengthen and prolong the Alzheimerlike tau hyperphosphorylation in N2a cells, suggesting the establishment of a cell model with early pathological events of Alzheimer‘s disease.     

1型糖尿病葡萄糖代谢与胰岛素信号传导途径异常导致大鼠海马Alzheimer样tau蛋白过度磷酸化修饰

Tau蛋白过度磷酸化是Alzheimer病(Alzheimer disease, AD)的一个重要病理特征.采用 I 型糖尿病大鼠模型,研究胰岛素信号传导途径及葡萄糖代谢失调对tau蛋白过度磷酸化的形成机制进行探讨.以同龄Wistar大鼠做对照（CTL）,胰腺大部分切除造低胰岛素组（PX）,STZ较大剂量一次性注射造1型糖尿病模型即低胰岛素高血糖组（T1DM）.葡萄糖氧化酶法检测血浆血糖,放免法检测血浆胰岛素,蛋白质印迹分析海马内总tau蛋白及tau蛋白上部分位点（Ser199、Thr212、Ser214、Ser396及Ser422）的磷酸化及神经细胞膜上葡萄糖转运子3（Glucose transport 3,GLUT3）水平.γ-32P-ATP和特异性底物肽检测海马内胰岛素信号传导系统中的关键酶糖原合成酶激酶-3β（Glycogen synthase kinase-3β, GSK-3β）活性.发现3组大鼠海马回总tau蛋白水平无显著差异,但以高血糖、低胰岛素血症为特征的T1DM组在tau蛋白Ser199、Thr212、Ser214、Ser396及Ser422位点上,呈现过度磷酸化状态,以低胰岛素血症为特征而血糖正常的PX组在位点Ser199、Thr212及Ser396上磷酸化程度比CTL组显著上升, 在位点Ser214及 Ser422上的磷酸化程度的改变不显著;T1DM及PX组大鼠海马 GSK-3β活性显著高于CTL组, 而GLUT3水平在T1DM和PX组均降低, 尤以T1DM组降低更显著.研究结果显示,胰岛素水平低下可能通过激活GSK-3β和下调细胞内葡萄糖代谢的双重作用引起脑内tau蛋白过度磷酸化.     

PKB/ Akt 在高脂诱导鼠肾脏损害中的作用

目的:通过建立高脂血症大鼠模型,探讨单纯高脂对肾脏的损伤机制以及胰岛素传导通路中的关键酶PKB/Akt(丝氨酸/苏氨酸激酶)在高脂所致肾脏损害中的变化和意义。方法:高脂高胆固醇喂养Wistar雄性大鼠,建立胰岛素抵抗模型。分别在4周、8周、12周测定大鼠的肾功,包括血尿素蛋(BUN),肌酐(CREA);16周时测定甘油三酯(TG),胆固醇(TC),以及血糖(FBS)和胰岛素(FINS)。8周时行胰岛素增敏剂文迪雅(3mg/kg)灌胃干预四周,并行肾脏病理检查,应用免疫组化法监测PKB/Akt在肾脏的表达。结果:高脂喂饲大鼠4周后,进食量开始减少,体重增加减慢;血BUN、血CREA在4周时已升高,至8周时增加更明显(p<0.001)。文迪雅灌胃四周后肾功改善,但仍高于正常组(p<0.05)。血TG和血TC较正常组升高显著,统计学差异显著(p<0.05)。血胰岛素升高,但胰岛素敏感性降低,胰岛素抵抗指数增加显著,提示胰岛素抵抗形成。肾脏免疫组化PKB/Akt的表达呈现为在肾小球和肾小管分布不均,出现PKB/Akt在损伤较重的肾小球不表达,而在损伤较轻的肾小管表达减弱的现象。结论:饮食诱导的高脂血症可导致健康大鼠产生脂质肾毒性损害以及肾功的降低,并可产生胰岛素抵抗。胰岛素传导通路的损害在肾小球和肾小管表达不同,说明其可能是产生肾脏损伤及胰岛素抵抗的又一原因。胰岛素增敏剂可改善胰岛素抵抗及肾功。     

大豆类受体蛋白激酶基因GmRLCK的克隆及初步分析

植物类受体蛋白激酶(receptor-likeproteinkinase,RLK)在高等植物生长发育和环境刺激的信号传导中起着重要的作用。本文报告了一个新的大豆类受体蛋白激酶基因的全长cDNA克隆及对其基因结构和功能的初步分析。研究表明该基因序列编码的蛋白包含一个跨膜域、一个具有丝氨酸/苏氨酸激酶活性的胞内域和一个缺少N-末端信号肽的胞外域。采用生物信息学方法分析表明,该基因与一些拟南芥菜类受体蛋白激酶基因具有很高的相似性,这些激酶N-末端都缺少信号序列,属于植物胞质类受体激酶(receptor-likecytoplasmickinase,RLCK)亚家族。因此命名该大豆基因为GmRLCK(GenBankAccessionNo.AY687390)。对GmRLCK激酶域中磷酸化可能性较高的位点进行了预测。RT-PCR的结果表明,GmRLCK在大豆子叶、根、花以及豆荚中都有较高的表达,而在胚根、茎和成熟叶片中的表达相对较弱。进化分析表明GmRLCK与一些衰老相关的植物类受体蛋白激酶具有较近的亲缘关系。     

尾加压素Ⅱ抑制葡萄糖激酶的表达和葡萄糖诱导的胰岛素分泌

本研究旨在探讨尾加压素II(urotensin II,UII)对胰岛β细胞功能的影响及其机制。在整体实验中,采用Wistar大鼠进行糖耐量试验,检测不同剂量UII(3、30、300nmol/kg)对大鼠血糖和胰岛素水平的影响;在细胞实验中,βTC-6细胞孵育实验检测UII对葡萄糖引起的胰岛素分泌(glucose-induced insulin secretion,GIIS)的影响,酸化乙醇抽提法和实时荧光定量PCR分别测定细胞内胰岛素含量和mRNA的水平,Western blot检测胰十二指肠同源盒1(pancreatic duodenal homeobox-1,PDX-1)和葡萄糖激酶(glucokinase,GCK)表达水平。糖耐量试验结果显示,相对对照组,急性静脉注射较高剂量的UII(30、300nmol/kg)使大鼠血浆胰岛素浓度在腹腔注射葡萄糖后15min显著下降,并且使大鼠血糖在腹腔注射葡萄糖后90min明显升高。βTC-6细胞孵育实验结果显示,UII孵育2h能抑制βTC-6细胞的GIIS,但是对细胞内的胰岛素含量和mRNA水平没有影响。UII对GIIS的抑制作用可以被UII受体拮抗剂urantide所阻断,部分被蛋白激酶C(protein kinase C,PKC)非特异性抑制剂chelerythrine chloride(CTC)和生长抑素受体非特异性拮抗剂cyclosomatostatin(CSS)所阻断。Western blot结果显示,UII抑制了βTC-6细胞内GCK的表达,但对PDX-1表达量没有影响。以上结果表明,UII通过激活其特异性受体(较高浓度的UII可能同时激活生长抑素受体)抑制胰岛β细胞GIIS,其作用机制涉及PKC通路的激活、GCK表达受抑所引起的胰岛素颗粒胞吐作用的减弱,但不涉及胰岛素本身表达的下降。     

人参皂苷-Rh2诱导肿瘤细胞凋亡信号转导通路研究进展

人参皂苷-Rh2诱导肿瘤细胞凋亡机制复杂,且不同机制间相互联系。它主要通过调节细胞周期蛋白依赖性激酶复合物特异性信号传递引发细胞周期阻滞诱导细胞凋亡,或通过调控细胞信号转导通路,如ROS、Ca2+、PKC、JNK介导的线粒体信号通路和TRAIL-R1(DR4)介导的死亡受体信号通路等诱导肿瘤细胞凋亡。     

甘油二酯激酶α在结直肠癌中的表达及其与PKC、TNFα的相关性

目的探讨甘油二酯激酶α(DGKα)在结直肠癌中的表达及其与蛋白激酶C(PKC)、肿瘤坏死因子α(TNFα)表达的相关性。方法应用免疫组化方法检测DGKα、PKC和TNFα在48例结直肠癌、癌旁正常组织和9例腺瘤性息肉中的表达。结果 DGKα在结直肠癌组织和癌旁正常组织有表达,结直肠癌组织中DGKα阳性表达率(79.2%)显著高于腺瘤性息肉(阴性)和癌旁正常组织(33.3%,P0.05);PKC主要分布在结直肠癌和癌旁正常组织中,结直肠癌组织中PKC阳性表达率(35.4%)显著高于腺瘤性息肉(阴性),与癌旁正常组织(20.8%)相比无显著性差异(P0.05);TNFα在三种组织中均表达阳性,结直肠癌组织中TNFα阳性表达率(95.8%)显著高于腺瘤性息肉(55.6%,P0.05),与癌旁正常组织(87.5%)相比无显著性差异(P0.05);结直肠癌组织中,DGKα与PKC的表达呈负相关(r=-0.437,P0.05),与TNFα的表达没有相关性(r=0.185,P0.05)。结论DGKα在结直肠癌组织中的表达高于腺瘤性息肉,DGKα可能抑制了PKC的活性,但对TNFα没有明显的抑制作用,在临床病理鉴别诊断中有辅助价值。