LMP1 activates NF-κB via degradation of IκBα in nasopharyngeal carcinoma cells  

EB病毒LMP1在鼻咽癌细胞中通过IκBα的降解活化NF-κB(英文)

作　　者：殷莉群[1] 廖伟[1] 邓锡云[1] 唐敏[1] 顾焕华[1] 李晓艳[1] 易薇[1] 曹亚[1] 

机构地区：[1]湖南医科大学肿瘤研究所,湖南410078

出　　处：《Chinese Medical Journal》2001年第7期46-50,105-106,共7页中华医学杂志（英文版）

基　　金：ThisprojectwassupportedbytheStateKeyBasicResearchProgram ;FundamentalInvestigationonHumanCarcinogenesis (No G19980 5 12 0 1) ;theNationalScienceFundationforDistinguishedYoungScholars (No 395 2 0 2 2 ) ;andtheChinaMedicalBoardofNewYork ;Inc (N

摘　　要：Abstract:Objective To elucidate the mechanisms by which Epstein-Barr virus-encoded latent membrane protein 1 activates NF-κB in nasopharyngeal carcinoma cells.Methods A tetracycline-regulated LMP1-expressing nasopharyngeal carcinoma cell line, Tet-on-LMP1-HNE2, was used as the cell model. The kinetics of the expression of proteins, including LMP1, IκBα and IκBβ, was analyzed by Western blotting. The subcellular localization of NF-κB (p65) was detected by indirect immunofluorescence assay. The NF-κB transactivity was studied by transient transfection and reporter gene assay. Results IκBα was phosphorylated and degraded after the inducible expression of LMP1, although the total protein levels remained stable. The steady-state level of total IκBβ protein may have resulted from the initiation of an autoregulation loop after the activation of NF-κB. No change in the IκBβ level was detected. NF-κB (p65) was translocated from the cytoplasm to the nucleus following degradation of IκBα. After the introduction of the dominant-negative mutant of IκBα (Del 71) into Tet-on-LMP1-HNE2 cells, both nuclear translocation and transactivation of NF-κB induced by LMP1 was significantly inhibited. Conclusions The results indicated that in nasopharyngeal carcinoma cells, LMP1 activated NF-κB via phosphorylation and degradation of IκBα, but not IκBβ. The dominant-negative mutant of IκBα (Del 71) could completely inhibit both the nuclear translocation and transactivation of NF-κB induced by LMP1.目的　阐明鼻咽癌细胞中EB病毒编码的潜伏膜蛋白 1(LMP1)活化核转录因子NF κB的机制。方法　利用强力霉素Dox诱导表达LMP1的鼻咽癌细胞株Tet on LMP1 HNE2为实验模型 ,首先应用免疫印迹方法测定Dox诱导后不同时相LMP1的表达动力学以及IκBs蛋白量及功能的改变。进而用间接免疫荧光法检测NF κB的亚细胞定位。最后采用瞬间共转染及报道基因活性分析分析NF κB的活性。结果　在鼻咽癌细胞Tet on LMP1 HNE2中 ,Dox处理 15分钟后LMP1的表达迅速升高并维持与较高水平直至 12 0分钟。LMP1的诱导性表达导致IκBα的磷酸化并降解 ,但IκBα蛋白总量无改变。继IκBα的磷酸化并降解 ,NF κB(P6 5 )自胞浆易位至胞核且活性升高。IκBα的显性负性突变子抑制NF κB(P6 5 )的核易位及报道活性。LMP1的诱导性表达并未引起IκBβ蛋白水平变化。结论　在鼻咽癌细胞Tet on LMP1 HNE2中 ,EB病毒LMP1通过IκBα的磷酸化并降解激活核转录因子NF κB的活性 ,并且 ,LMP1诱导的NF κB活性能被IκBα的显性负性突变子完全抑制。IκBβ在此信号传导途径中无改变。LMP1表达前后IκBα蛋白总量维持恒定可能是由于NF κB的活化迅速启动了IκBα的重头合成这一自身调节环路所致。

关 键 词：Epstein  Barr virus  ·   latent membrane protein ·   NF  κB  · IκBα  ·   nasopharyngeal carcinoma 

分 类 号：R739.62[医药卫生—肿瘤]