The chromatin loop release factor WAPL regulates EBV latency status by restricting LMP production

Epstein-Barr virus (EBV) is a ubiquitous human pathogen that is etiologically linked to several cancers and has been connected to multiple sclerosis. EBV employs a series of latency programs, including latency III, latency II, and latency I, to persistently colonize the B-cell compartment. Each of these programs is associated with human malignancies. However, our understanding remains incomplete of how these distinct latency programs are epigenetically restricted. While regulation of the chromatin structure of the EBV genome by cohesin and CTCF contributes to genome regulation, the function of the cohesin release factor Wings Apart-Like Protein Homolog (WAPL) had not previously been understood. In this study, we employ RNA-seq combined with immunofluorescence analysis to determine that loss of WAPL leads to aberrant expression of the oncogenic latent membrane proteins LMP1 and LMP2A in latency I Burkitt lymphoma cells. Through a combination of Hi-C, Hi-ChIP, and ChIP-qPCR, we uncover that WAPL loss causes alterations in looping across the EBV genome and specifically induces formation of loops between the LMP promoter and the oriLyt enhancers. We propose that EBV coopts WAPL to maintain a strict latency I state and, without WAPL, leaky expression of the LMP proteins occurs. HiC sequencing of EBV genome in WAPL WT and KO cell lines