Rewiring of B cell receptor signaling by Epstein-Barr virus LMP2A

ABSTRACT: Epstein-Barr virus (EBV) infects human B cells and reprograms them to allow virus replication and persistence. One key viral factor in this process is latent membrane protein 2A (LMP2A), which has been described as a B cell receptor (BCR) mimic promoting malignant transformation. However, how LMP2A signaling contributes to tumorigenesis remains elusive. By systematically comparing LMP2A and BCR signaling using quantitative phosphoproteomics and transcriptome profiling, we identified molecular mechanisms through which LMP2A affects B cell biology. Consistent with previous literature, we found that LMP2A mimics a subset of BCR signaling events, including tyrosine-phosphorylation of the kinase SYK, the calcium initiation complex consisting of BLNK, BTK, PLC2, and its downstream transcription factor NFAT. However, the vast majority of LMP2A-induced signaling events markedly differed from those induced by BCR stimulation. These included differential phosphorylation of kinases, phosphatases, adaptor proteins, transcription factors such as NFB and TCF3, as well as widespread changes in the transcriptional output of LMP2A-expressing B cells. LMP2A affected apoptosis and cell cycle checkpoints by dysregulating the expression of apoptosis regulators such as Bcl-xL and the tumor suppressor retinoblastoma-associated protein (RB1). Accordingly, LMP2A cooperated with drivers of Burkitt lymphoma, overexpressed MYC and an oncogenic cyclin D3 mutant, by counteracting the pro-apoptotic effects of MYC and by further inhibiting RB1 function to promote cell growth. Our results indicate that LMP2A rewires rather than mimics BCR signaling, promoting a signaling output that predisposes EBV-infected B cells to hyperproliferation and eventual malignant transformation.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): B Cell, Lymph Node

DISEASE(S): Lymphoma

SUBMITTER: Yanlong Ji  

LAB HEAD: Thomas Oellerich

PROVIDER: PXD018566 | Pride | 2020-09-22

REPOSITORIES: Pride