Biology subjects

Cable, J. M.

Publications and source records attributed to Cable, J. M..

3 recordsLinked to original sources

bioRxiv2024

Sp140L Is a Novel Herpesvirus Restriction Factor

Herpesviruses, including Epstein-Barr Virus (EBV) - a human oncogenic viruses and essential trigger of multiple sclerosis, must bypass host DNA sensing mechanisms to establish lifelong, latent infection. Therefore, herpesviruses encode viral proteins to disrupt key host factors involved in DNA sensing and viral restriction. The first viral latency protein expressed, EBNA-LP, is essential for transformation of naive B cells and establishment of viral gene expression, yet its role in evading host defenses remains unclear. Using single-cell RNA sequencing of EBNA-LP-Knockout (LPKO)- infected B cells, we reveal an antiviral response landscape implicating the speckled proteins as key cellular restriction factors countered by EBNA-LP. Specifically, loss of SP100 or the primate-specific SP140L reverses the restriction of LPKO, suppresses a subset of canonically interferon-stimulated genes, and restores transcription of essential latent viral genes and cellular proliferation. Notably, we also identify Sp140L as a restriction target of the herpesvirus saimiri ORF3 protein, implying a role for Sp140L in immunity to other diverse DNA viruses. This study reveals Sp140L as a restriction factor that we propose links sensing and transcriptional suppression of viral DNA to an IFN-independent innate immune response, likely relevant to all nuclear DNA viruses. Significance StatementHerpesviruses, including the oncogenic Epstein-Barr virus (EBV), are restricted by DNA sensing during initial infection and therefore encode viral proteins to antagonize key restriction factors. We found that the EBV latency protein EBNA-LP, disrupts the speckled proteins Sp100 and Sp140L - an evolutionarily recent protein with unknown function, which we find promotes an anti-viral state that suppresses cellular proliferation, characterized by high induction of cellular anti-viral genes and suppressed transcription of essential viral latency genes. Sp140L also restricts the herpesvirus saimiri, which we find antagonizes Sp140L through the viral protein ORF3. Our study therefore identifies Sp140L as a novel restriction factor of diverse herpesviruses, and likely all DNA viruses, during a critical stage of initial viral infection.

microbiology↗

bioRxiv2024

Epstein-Barr virus protein EBNA-LP engages YY1 through leucine-rich motifs to promote naïve B cell transformation

Epstein-Barr Virus (EBV) is associated with numerous cancers including B cell lymphomas. In vitro, EBV transforms primary B cells into immortalized Lymphoblastoid Cell Lines (LCLs) which serves as a model to study the role of viral proteins in EBV malignancies. EBV induced cellular transformation is driven by viral proteins including EBV-Nuclear Antigens (EBNAs). EBNA-LP is important for the transformation of naive but not memory B cells. While EBNA-LP was thought to promote gene activation by EBNA2, EBNA-LP Knock Out (LPKO) virus-infected cells express EBNA2-activated genes efficiently. Therefore, a gap in knowledge exists as to what roles EBNA-LP plays in naive B cell transformation. We developed a trans-complementation assay wherein transfection with wild-type EBNA-LP rescues the transformation of peripheral blood- and cord blood-derived naive B cells by LPKO virus. Despite EBNA-LP phosphorylation sites being important in EBNA2 co-activation; neither phospho-mutant nor phospho-mimetic EBNA-LP was defective in rescuing naive B cell outgrowth. However, we identified conserved leucine-rich motifs in EBNA-LP that were required for transformation of adult naive and cord blood B cells. Because cellular PPAR-{gamma} coactivator (PGC) proteins use leucine-rich motifs to engage transcription factors including YY1, a key regulator of DNA looping and metabolism, we examined the role of EBNA-LP in engaging cellular transcription factors. We found a significant overlap between EBNA-LP and YY1 in ChIP-Seq data and confirmed their biochemical association in LCLs by endogenous co-immunoprecipitation. Moreover, we found that the EBNA-LP leucine-rich motifs were required for YY1 interaction in LCLs. Finally, we used Cas9 to knockout YY1 in primary total B cells and naive B cells prior to EBV infection and found YY1 to be essential for EBV-mediated transformation. We propose that EBNA-LP engages YY1 through conserved leucine-rich motifs to promote EBV transformation of naive B cells. Author SummaryEpstein-Barr Virus (EBV) is associated with various B cell lymphomas, particularly in immunosuppressed individuals. In the absence of a functional immune system, viral latency proteins, including EBV Nuclear Antigens (EBNAs) act as oncoproteins to promote tumorigenesis. EBNA-LP is one of the first viral proteins produced after infection and is important for the transformation of naive B cells. However, the roles of EBNA-LP during infection are largely undefined. In this study, developed an assay in which the role of wild type and mutant EBNA-LP could be investigated in context of primary naive B cells infected with an EBNA-LP Knock Out virus. Using this assay, we identified highly conserved leucine-rich motifs within EBNA-LP that are important for transformation of EBV-infected naive B cells. These conserved motifs associate with the cellular transcription factor YY1, an important transcriptional regulator in B cell development and in many cancers, that we now show is essential for outgrowth of EBV infected B cells. Our study provides further insights into the mechanisms by which EBV transforms naive B cells.

microbiology↗

bioRxiv2020

Monocarboxylate transporter antagonism reveals metabolic vulnerabilities of viral-driven lymphomas

Epstein-Barr Virus (EBV) is a ubiquitous herpesvirus that typically causes asymptomatic infection but can promote B lymphoid tumors in the immune-suppressed. In vitro, EBV infection of primary B cells stimulates glycolysis during immortalization into lymphoblastoid cell lines (LCLs). Lactate export during glycolysis is crucial for continued proliferation of many cancer cells-part of a phenomenon known as the "Warburg effect," and is mediated by the monocarboxylate transporters 1 and 4 (MCT1 and MCT4). However, the role of MCT1/4 has yet to be studied in EBV-associated malignancies which display Warburg-like metabolism in vitro. Here, we show that EBV infection of B lymphocytes directly promotes temporal induction of MCT1 and MCT4 through the viral proteins EBNA2 and LMP1 respectively, with MCT1 being induced early after infection and MCT4 late. Remarkably, singular MCT1 inhibition early, and dual MCT1/4 inhibition in LCLs using a novel MCT4-selective inhibitor led to growth arrest and lactate buildup. Metabolic profiling in LCLs revealed significatly reduced oxygen consumption rates (OCR) and NAD+/NADH ratios, contrary to prevous observations of increased OCR and unaltered NAD+/NADH ratios in MCT1/MCT4-inhibited cancer cells. Furthermore, U-13C6 glucose labeling of MCT1/4-inhibited LCLs also revealed increased labeling of glutathione in the presence of elevated ROS and depleted glutathione pools, as well as increased labeling of de novo pyrimidine biosynthetic intermediates, suggesting broad effects on LCL metabolism. These vulnerabilities sensitized LCLs as well as EBV+, and the related gammaherpesvirus KSHV+ lymphoma cell lines to killing by metformin and phenformin, pointing at a novel therapeutic approach for viral lymphomas.

cancer biology↗