Biology subjects

Burton, E. M.

Publications and source records attributed to Burton, E. M..

3 recordsLinked to original sources

bioRxiv2026

A CRISPR-Cas9 screen Reveals STEEP1 as a Key Host Dependency Factor for Epstein-Barr Virus Latent Membrane Protein 1 Trafficking and Signaling

The Epstein-Barr virus (EBV) oncogene Latent membrane protein 1 (LMP1) is essential for B-cell transformation into continuously growing lymphoblastoid cell lines. LMP1 traffics to plasma membrane and intracellular signaling sites to mimic aspects of signaling by the B cell co-receptor CD40. LMP1 is expressed in many EBV-associated cancers, including post-transplant lymphoma, Hodgkin lymphoma, T/NK lymphoma and nasopharyngeal carcinoma, where it activates key growth and survival pathways. LMP1 signaling is also implicated in multiple sclerosis pathogenesis. To identify host dependency factors that support LMP1 trafficking and signaling, we performed a human genome-wide CRISPR-Cas9 screen in B cells. The screen identified both known and previously uncharacterized mediators of LMP1 signaling. The ER resident protein STEEP1, implicated in DNA sensor STING trafficking and signaling, was a top screen hit. Importantly, STEEP1 did not score in our prior B cell CRISPR screen for factors that support CD40 signaling, suggesting specificity. STEEP1 depletion strongly impaired LMP1 signaling, including activation of NF-kB and MAP kinase pathways. Mechanistically, STEEP1 associated with LMP1 in a manner dependent on the N-terminal cytoplasmic tail and supported LMP1 egress from the ER to signaling sites in both B and epithelial cells. Collectively, these findings reveal STEEP1 as a key host factor that supports trafficking of newly synthesized LMP1 molecules to intracellular signaling sites and highlights LMP1/STEEP1 interaction as a novel therapeutic target. ImportanceEpstein-Barr virus (EBV) infects most people worldwide. While infection is often benign, it causes infectious mononucleosis, is associated with a range of lymphomas, nasopharyngeal and gastric carcinoma and is a major trigger for autoimmune disease, including multiple sclerosis. The EBV encoded oncogene LMP1 is a key driver of EBV pathogenesis, and its signaling is necessary for viral immortalization of B lymphocytes into continuously growing lymphoblasts (LCLs). Here, we performed a CRISPR genetic screen to identify host factors that support continuous, ligand-independent signaling by LMP1. This analysis identified an ER-resident protein called STEEP1, previously implicated in support of trafficking of the DNA sensor STING, as a key LMP1 partner. We found that STEEP1 associates with LMP1 and supports LMP1 trafficking out of the endoplasmic reticulum to cellular signaling sites. As STEEP1 knockout impaired LMP1 function and LCL survival, our study identifies the STEEP1/LMP1 complex as a therapeutic target.

microbiology↗

bioRxiv2026

Epstein-Barr Virus Latent Membrane Protein 1 Suppresses Ferroptosis via Pentose Phosphate Pathway and Glutathione Metabolism

Epstein-Barr virus (EBV) is associated with 200,000 cancers per year, including Burkitt lymphoma and post-transplant lymphomas. We previously reported that EBV latency oncogene programs dynamically remodel infected B cell metabolism and sensitivity to induction of ferroptosis, a programmed cell death pathway driven by lipid reactive oxygen species. However, much has remained unknown about how EBV remodels key redox defense pathways in support of infected B cell proliferation. Here, we identify EBV latent membrane protein 1 (LMP1), a key viral oncogene necessary for B cell immortalization and which mimics aspects of CD40 signaling, drives resistance to ferroptosis induction by erastin, a small molecule that blocks cystine uptake. LMP1 expression was sufficient to protect Burkitt cells from erastin ferroptosis induction. Mechanistically, signaling from the LMP1 TES2/CTAR2 region drove this phenotype, which was not shared by CD40 signaling, revealing that LMP1 evolved independent redox defense roles. Metabolomic analysis highlighted key LMP1 and TES2 signaling roles in support of antioxidant cysteine and glutathione levels. TES2 signaling supported cystine uptake, glutathione and NADPH pools in newly infected peripheral blood B cells. We identified PFKFB4, a host enzyme that shunts glucose into the pentose phosphate pathway to support NADPH production, as a major TES2 metabolic target. PFKFB4 knockdown increased EBV-transformed lymphoblastoid cell line lipid ROS levels, decreased glutathione and strongly sensitized them to ferroptosis induction by erastin treatment. PFKFB4 was also necessary for LMP1-mediated Burkitt B cell ferroptosis resistance. Collectively, these results identify PFKFB4 as a key host cell EBV metabolism remodeling target critical for infected B cell redox defense.

microbiology↗

bioRxiv2022

Epstein-Barr virus latency programs dynamically sensitize B-cells to ferroptosis

Epstein-Barr virus (EBV) causes 200,000 cancers annually. Upon B-cell infection, EBV induces lipid metabolism to support B-cell proliferation. Yet, little is known about how latent EBV infection, or human B-cell stimulation more generally, alter sensitivity to ferroptosis, a non-apoptotic form of programmed cell death driven by iron-dependent lipid peroxidation and membrane damage. To gain insights, we analyzed lipid reactive oxygen species (ROS) levels and ferroptosis vulnerability in primary human CD19+ B-cells infected by EBV or stimulated by key B-cell receptors. Prior to the first mitosis, EBV-infected cells were exquisitely sensitive to blockade of glutathione biosynthesis, a phenomenon not observed with B-cell receptor stimulation. Subsequently, EBV-mediated Burkitt-like hyper-proliferation generated elevated levels of lipid ROS, which necessitated SLC7A11-mediated cystine import and glutathione peroxidase 4 (GPX4) activity to prevent ferroptosis. By comparison, B-cells were sensitized to ferroptosis induction by combinatorial CD40-ligand and interleukin-4 stimulation or anti-B-cell receptor and Toll-like receptor 9 stimulation upon GPX4 inhibition, but not with SLC7A11 blockade. EBV transforming B-cells became progressively resistant to ferroptosis induction upon switching to the latency III program and lymphoblastoid physiology. Similarly, latency I Burkitt cells were particularly vulnerable to blockade of SLC7A11 or GPX4 or cystine withdrawal, while latency III Burkitt and lymphoblastoid cells were comparatively resistant. The selenocysteine biosynthesis kinase PSTK was newly implicated as a cellular target for ferroptosis induction including in Burkitt cells, likely due to roles in GPX4 biosynthesis. These results highlight ferroptosis as an intriguing therapeutic target for the prevention or treatment of particular EBV-driven B-cell malignancies. SignificanceEBV contributes to B-cell Burkitt and post-transplant lymphoproliferative disease (PTLD). EBV transforming programs activate lipid metabolism to convert B-cells into immortalized lymphoblastoid cell lines (LCL), a PTLD model. We found that stages of EBV transformation generate lipid reactive oxygen species (ROS) byproducts to varying degrees, and that a Burkitt-like phase of B-cell outgrowth is dependent on lipid ROS detoxification by glutathione peroxidase 4 and its cofactor glutathione. Perturbation of this redox defense in early stages of B-cell transformation or in Burkitt cells triggered ferroptosis, a programmed cell death pathway. LCLs were less dependent on this defense, a distinction tied to EBV latency programs. This highlights ferroptosis induction as a novel therapeutic approach for prevention or treatment of EBV+ lymphomas.

microbiology↗