Role of Epstein-Barr Virus Zebra protein in induction of t(8;14) translocation

• Published in: Biopolimery i kletka 2019-05, Vol.35 (3), p.230-231
• Main Authors: Sall, F. B., Germini, D., Shmakova, A., Diouf, P. M. D., Wiels, J., Ndour, M., Touré, A. O., Vassetzky, Y.
• Format: Article
• Language: English
• Subjects: Burkitt's lymphoma; Children; Chromosome 8; Chromosome translocations; Chromosomes; Epstein-Barr virus; Gene loci; Heavy chains; Immunoglobulins; Latency; Life cycles; Lymphocytes B; Lymphoma; Myc protein; Non-Hodgkin's lymphoma; ZEBRA protein
• ISSN: 0233-7657; 1993-6842
• DOI: 10.7124/bc.0009F6

Burkitt lymphoma (BL) is an aggressive Non-Hodgkin Lymphoma characterized by a chromosomal translocation involving the MYC oncogene located on the chromosome 8 and one of the immunoglobulin gene loci located on the chromosomes 2, 14 or 22. The African endemic form of BL is associated with the Epstein Barr Virus (EBV). EBV life cycle includes two phases: lytic and latent. The switch from latency to lytic cycle (EBV reactivation) is initiated by the EBV Zebra protein. We study the role of EBV reactivation in the formation of one BL characteristic translocation t(8;14). Our hypothesis is that the Zebra- triggered EBV reactivation provokes nuclear architecture remodeling in B-cells and induces spatial proximity (colocalization) of MYC and IGH loci. In theory, the closer the two loci are, the higher the probability of translocation between them is. Methods: 3D FISH was used to study MYC and IGH loci proximity in B-cell lines, in naïve B-cells from healthy donors and in B-cells from EBV-infected African children. These children were divided into three groups according to their infection status (no infection, latency and reactivation). We used an EBV-positive B-cell line inducibly expressing Cas9 and gRNAs targeting MYC and IGH loci to study the consequence of prolonged MYC-IGH proximity on the occurrence of BL characteristic translocation t(8;14). After induction of DSBs in the targeted loci, the translocation (8;14) occurs with a frequency of 2x10-3 and is detectable by qPCR. Results: We demonstrated that EBV reactivation by various methods in our model significantly increases MYC-IGH colocalization rate. The same effect was not observed in B-cells from healthy donors treated with Zebra suggesting involvement of EBV in this process. Also, in children, no difference was observed between the latency and reactivation groups, probably due to the very low percentage of EBV-infected B-cells in vivo (less than 1%). Then, exploiting our model, we found that EBV reactivation increased both MYC-IGH proximity and translocation rate when DSBs were induced on MYC and IGH. Conclusion: Our work provides the first experimental proof that spatial proximity loci increases the probability of translocations between these loci and explains the link between EBV and specific chromosomal translocations leading to BL.