c-cbl对于K_(562)细胞增殖作用的研究

目的 :研究 p1 2 0参与的信号转导途径与 CML细胞增殖的关系。方法 :利用反转录聚合酶链反应 ( RT-PCR)的方法 ,从人慢性粒细胞白血病 ( CML )细胞系 K5 6 2 细胞中扩增包括 c-cbl基因上游调控区及 5′翻译起始区的一段共 52 3bp c DNA序列 ,反向插入真核表达载体 pc DNA3 .1 ( ) ,转染 K5 6 2细胞系。通过 MTT及集落形成实验检测转基因 K5 6 2 细胞增殖能力的变化 ,研究 c-cbl反义 RNA封闭c-cbl转录产物对于 K5 6 2 细胞增殖的影响。结果 :该种反义封闭作用使 K5 6 2 细胞增殖及集落形成速度明显减慢。结论 :p1 2 0 CBL与 CML细胞的增殖有关。     

Contrasting effects of insulin and cellular differentiation on expression of the novel insulin receptor substrate APS in skeletal muscle

The novel insulin receptor substrate protein APS is highly expressed in insulin-sensitive tissues and plays an important role in insulin-mediated glucose uptake and GLUT4 translocation via the Cbl/CAP pathway. Tyrosine phosphorylation of APS leads to recruitment of c-Cbl and Crk, while overexpression of APS mutant inhibits GLUT4 translocation in response to insulin, but the regulation of APS expression in skeletal muscle has not been previously reported. L6 myoblasts were differentiated in 2% FBS and serum starved for 24 h prior to stimulation for 24 h with either insulin 1 μM (n = 6), rosiglitazone 10 μM (n = 6), resistin 500 nM (n = 6) or the MAP kinase inhibitor PD098059 50 μM (n = 6) for 30 min, followed by insulin 1 μM for 24 h. Semi-quantitative real-time RT-PCR was used to determine the expression of APS mRNA relative to the control gene TF2D. APS expression was markedly upregulated by myoblast differentiation (0.55 ± 0.08 versus 1.14 ± 0.08, p = 0.001), and this effect was augmented by addition of rosiglitazone 10 μM for 24 h to the differentiated myotubes (1.50 ± 0.09, p = 0.025). Insulin caused a 3.1-fold decrease in APS mRNA expression (0.37 ± 0.01 versus 1.14 ± 0.08, p = 0.001), an effect that was attenuated by the MAP kinase inhibitor PD098059 (0.80 ± 0.03, p = 0.001). Exposure to resistin produced a modest decrease (1.4-fold) in myotube expression of APS (0.8 ± 0.09, p = 0.025). In conclusion, this is the first study to show that exposure to insulin markedly reduces the expression of APS in skeletal muscle via a MAP kinase dependent pathway, whereas myocyte differentiation and rosiglitazone increase APS expression. Changes in APS expression may be important in the aetiology and therapeutic reversal of insulin resistance in skeletal muscle.     

cblN/Zap嵌合分子的构建及其对Jurkat细胞TCRζ的下调

目的:构建cblN/Zap嵌合分子,稳定转染Jurkat细胞后观察对细胞TCRζ的影响。方法:提取Jurkat细胞的总RNA并反转录为cDNA,以其作为模板用PCR方法扩增Zap基因的SH2片段。以含有人全长cblcDNA的质粒pEFHAcbl作为模板扩增cbl基因的N端(cblN),并在其N末端带上含24bp的flag标签。用重叠延伸PCR法,在cblN基因内部的SH2两端引入BamHI和EcoRV酶切位点并克隆入pcDNA3.1( )中。再以Zap基因的SH2置换cblN基因的SH2,即成为pcDNA3.1( )cblN/Zap。酶切鉴定及测序正确后,采用脂质体法稳定转染Jurkat细胞,用RTPCR和Westernblot鉴定flagcblN/Zap的表达,用Westernblot检测其对细胞TCRζ表达的影响。结果:重组质粒pcDNA3.1( )flagcblN/Zap经酶切后可产生与理论预期长度相符的片段。且测序证实其序列正确。脂质体法稳定转染Jurkat细胞后,检测到目的基因在RNA和蛋白水平的表达。表达的cblN/Zap可下调Jurkat细胞的TCRζ。结论:重构嵌合分子cblN/Zap可下调Jurkat细胞的TCRζ。     

The cbl oncogene: a novel substrate of protein tyrosine kinases

The cbl oncogene was first identified as part of a transforming retrovirus which arose in a mouse pre-B cell lymphoma. Its protein product, p120^cbl, is cytoplasmic and has several distinctive domains including a highly basic region, a RING finger motif and a large proline-rich domain. A mutation to cbl in the 70Z/3 pre-B cell lymphoma produces an oncogenic protein which exhibits a marked enhancement of tyrosine phosphorylation. Parallel studies have demonstrated that P120^cbl is a substrate of protein tyrosine kinases activated by engagement of the T cell antigen receptor and that cbl is phosphorylated by oncogenic forms of the Abl tyrosine kinase. These studies also demonstrated a constitutive association between cbl and the SH3 domains of the Grb2 and Nek adaptor proteins in a range of haemopoietic cell lines. More recently it has been found that cbl is rapidly phosphorylated following stimulation of the EGF receptor, Fey receptor, c-Kit receptor and CSF-1 receptor. A genetic analysis in Caenorhabditis elegans has identified a cbl homologue, called sli-1, that negatively regulates the LET-23 tyrosine kinase receptor. These characteristics indicate a central role for cbl in the regulation of intracellular signals that are mediated by growth factors and antigenic stimuli which activate protein tyrosine kinases.     

Mutations of c-Cbl in myeloid malignancies

Next generation sequencing has shown the frequent occurrence of point mutations in the ubiquitin E3 ligase c-Cbl in myeloid malignancies. Mouse models revealed a causal contribution of c-Cbl for the onset of such neoplasms. The point mutations typically cluster in the linker region and RING finger domain and affect both alleles by acquired uniparental disomy. The fast progress in the detection of c-Cbl mutations is contrasted by our scarce knowledge on their functional consequences. The c-Cbl protein displays several enzymatic functions by promoting the attachment of differentially composed ubiquitin chains and of the ubiquitin-like protein NEDD8 to its target proteins. In addition, c-Cbl functions as an adapter protein and undergoes phosphorylation-dependent inducible conformation changes. Studies on the impact of c-Cbl mutations on its functions as a dynamic and versatile adapter protein, its interactomes and on its various enzymatic activities are now important to allow the identification of druggable targets within the c-Cbl signaling network.     

人cbl 基因真核表达载体的构建及表达

目的: 构建带有flag标签的人cbl 基因真核表达载体,并检测其在真核细胞中的表达.方法: 以含有人全长cbl cDNA的质粒pEFHAcbl 为模板,采用PCR方法扩增cbl基因,并在其N-末端带上含24 bp的flag标签,克隆到pGEM-T easy载体并测序,再亚克隆至真核表达载体pcDNA3.1( ),酶切鉴定正确后采用脂质体法瞬时转染COS-7细胞,Western blot检测flag-cbl在细胞中的表达. 结果: 测序证实以pEFHAcbl 为模板获得的flag-cbl融合基因的序列以及读框全部正确;重组质粒pcDNA3.1( )-flag-cbl经酶切后产生与理论预期长度相符的片段;脂质体法转染COS-7后检测到预期目的蛋白的表达.结论: 成功构建了N-末端带flag标签的cbl真核表达载体,并使其在真核细胞COS-7中表达.     

泛素连接酶cbl家族蛋白调控死亡受体信号通路的研究进展

死亡受体信号通路是引起细胞凋亡,维持细胞稳态的重要途径,对监视机体肿瘤具有重要意义.死亡受体通路主要包括三条:TNFα及其受体途径,FasL/Fas途径,TARIL及其受体DR4/5途径.近年来,关于cbl家族蛋白调控死亡受体通路的研究越来越多.cbl家族蛋白作为泛素连接酶Ring-finger结构域家族的重要成员之一,通过调节蛋白的泛素化,参与体内的多种生理过程.本文就死亡受体、脂筏、生存通路及其它分子四个方面,综述cbl家族蛋白调控死亡受体信号通路的研究进展.