[Epstein-Barr virus-encoded latent membrane protein 1 mediates serine-phosphorylation of annexin I by activating protein kinase C].
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.
Yan
Guang-Rong
GR
Institutes of Life and Health Engineering, Jinan University, Guangzhou, Guangdong, 510632, P. R. China. jxygr007@126.com
Luo
Wei
W
Luo
Xiang-Jian
XJ
Cao
Ya
Y
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
D017305:Annexin A1; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D014763:Viral Matrix Proteins; D014443:Tyrosine; D012694:Serine; D011493:Protein Kinase C