Alpha-satellite RNAs in Epstein-Barr virus lytic replication

About This Grant

SUMMARY Epstein-Barr virus (EBV) is a ubiquitous DNA tumor virus that is causally linked to Hodgkin's and non- Hodgkin's lymphoma, nasopharyngeal carcinoma, stomach cancer, and autoimmune diseases. EBV is particularly problematic in the HIV/AIDS population where EBV-associated lymphomas are especially prevalent. There are two distinct stages in EBV's life cycle: latency and lytic reactivation/replication. The viral lytic replication stage is a key component of the EBV infection cycle that facilitates the spread of the virus not only from host to host but also its dissemination within an infected individual. While EBV latency genes are long known to contribute to the tumor phenotype, EBV lytic replication is a precursor of (through dissemination) and a direct contributor to EBV-associated pathologies including lymphomas and autoimmune diseases. EBV is known to elicit a series of host cellular responses and it can almost always find a way to hijack these host machineries for its own benefits. For instance, EBV infection induces double-stranded breaks (DSBs) and strong DNA damage response (DDR) in host cells. It appears that EBV utilizes a variety of strategies to purposely activate the upstream/early steps of DDR signaling and inactivate the harmful downstream/late steps to ensure cell survival and benefit its own self-preservation. Recently, we have found that EBV lytic replication causes substantial induction of alpha-satellite RNAs (α-SatRNA), a novel host cellular response. This motivates us to further explore its significance in EBV lytic replication. Alpha-satellite DNA (α-SatDNA) is one type of tandem repetitive non-coding (nc) DNA sequences and constitutes 3-5% of the human genome. It also serves as the main building blocks for centromeres and has long been viewed as transcriptionally inert. Surprisingly, these genomic “dark matter” can be actively transcribed by RNA polymerase II to produce non- polyadenylated α-SatRNAs. The unique long repetitive sequence also makes α-SatRNAs a novel class of long ncRNAs. Our preliminary findings show that α-SatRNA levels are substantially induced by EBV lytic replication, accompanied by DNA damage DSBs and ATM activation. We further found that α-SatRNAs are required for efficient EBV lytic replication and α-SatRNAs promote ATM/upstream DDR signaling globally. Based on our published and unpublished findings, we hypothesize that lytic reactivation-induced DSBs on host centromeric α-SatDNA upregulate α-SatRNAs, which subsequently facilitate lytic reactivation by promoting ATM/upstream DDR signaling globally. In this proposal, we will test this hypothesis, we will begin to address the mechanisms through which EBV utilizes α-SatRNAs to facilitate its lytic replication and we will begin to address the mechanisms by which EBV reactivation induces α-SatRNA expression. Together, completion of this work will reveal a novel role of these “understudied” α-SatRNAs and associated underlying mechanisms in EBV lytic replication, and thus add conceptually to our understanding of EBV-host interaction.