title: [Epstein-Barr virus-encoded latent membrane protein 1 mediates serine-phosphorylation of annexin I by activating protein kinase C].
abstract: OBJECTIVE
  Twenty-five novel phosphoproteins, including Annexin I, triggered by Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) were identified when we previously combined phosphorylation enrichment with proteomics technology to elucidate signaling pathway activated by LMP1. This study was to map signal transduction pathway between LMP1 and phosphorylation of AnnexinI.
  
  
  METHODS
  The expression of Annexin I in nasopharyngeal carcinoma cell lines (stably expressing LMP1) was analyzed by Western blot. Serine-and tyrosine-phosphorylation levels of AnnexinIwere detected through combining immunoprecipitation with Western blot. The activity of protein kinase C (PKC) was analyzed by non-radioactive protein kinase assay.
  
  
  RESULTS
  The protein level and tyrosine phosphorylation of Annexin I in CNE1 and CNE1-LMP1 cells were similar; the serine phosphorylation of annexin I was higher in CNE1-LMP1 cells than in CNE1 cells. The relative activity of PKC was significantly lower in CNE1 cells than in CNE1-LMP1 cells (0.97+/-0.05 vs. 1.22+/-0.10, P<0.01). The change of PKC activity was followed by the change of serine phosphorylation level of Annexin I.
  
  
  CONCLUSIONS
  LMP1 mediates serine phosphorylation of Annexin I via PKC pathway.
authors.affiliation: Institutes of Life and Health Engineering, Jinan University, Guangzhou, Guangdong, 510632, P. R. China. jxygr007@126.com
authors.forename: Guang-Rong
authors.initials: GR
authors.lastname: Yan
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Xiang-Jian
authors.initials: XJ
authors.lastname: Luo
authors.forename: Ya
authors.initials: Y
authors.lastname: Cao
mesh_terms: D017305:Annexin A1 / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D012694:Serine / Q000737:chemistry*; D015398:Signal Transduction; D014443:Tyrosine / Q000737:chemistry; D014763:Viral Matrix Proteins / Q000378:metabolism* / Q000502:physiology
chemical_list: D017305:Annexin A1; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D014763:Viral Matrix Proteins; D014443:Tyrosine; D012694:Serine; D011493:Protein Kinase C