Biology subjects

Usherwood, E. J.

Publications and source records attributed to Usherwood, E. J..

5 recordsLinked to original sources

bioRxiv2026

A novel wild-derived MHC-linked locus regulates host immunity to gammaherpesvirus infection

Inefficient host control of infection by gammaherpesviruses is a risk factor for lymphoproliferative disease, autoimmunity, and cancer, yet naturally occurring genetic determinants of viral control remain poorly defined. Previously, we discovered that wild-derived PWD/PhJ (PWD) mice exhibit markedly improved control of murine gammaherpesvirus 68 (MHV-68) replication compared with C57BL/6J (B6) mice. This elite control of viral replication was linked to muted T cell responses, but partially dependent on NK cells. Here, we used genetic approaches to identify host determinants controlling MHV-68 resistance in PWD mice. Analysis of B6PWDF1 and B6PWDF2 populations suggested the existence of a major locus in the PWD genome contributing to MHV-68 resistance. Using B6.ChrPWD chromosome substitution (consomic) mice, we mapped a major resistance locus to Chr 17 and refined the required interval to 27.6-49.4 Mb, including the MHC locus. While B6.Chr17PWD mice recapitulated muted T cell responses observed in PWD mice, they controlled viral burden independent of NK cells and without reduced frequencies of infected germinal center B cells, indicating that resistance of PWD mice comprises multiple genetically and mechanistically distinct pathways. While the NK cell receptor complex on PWD chromosome 6 did not provide protection, genotype-phenotype analysis of the B6PWDF2 cohort revealed additional non-Chr 17-linked loci contributing to viral control. Together, our results identify a novel MHC-linked locus regulating gammaherpesvirus burden with minimal cytotoxic T cell expansion, demonstrating that effective host control of gammaherpesviruses can be achieved by diverse immune mechanisms. ImportancePoor host control of human gammaherpesvirus infection is linked to cancer and autoimmunity, but how natural genetic variation impacts immune mechanism of control is poorly defined. In this study, we examined genetic mechanisms linked to superior control of gammaherpesvirus infection. We identified a novel MHC-linked locus that regulates gammaherpesvirus burden without a large expansion of cytotoxic T cells and independent of NK cells. These findings show that host control of gammaherpesviruses can be achieved through diverse immune mechanisms that are driven by variation in host genetic background.

immunology↗

bioRxiv2025

The tumour suppressor LACTB remodels mitochondria to promotecytochrome c release and apoptosis

Mitochondria are pivotal regulators of cellular homeostasis, integrating energy metabolism, biosynthesis, and programmed cell death (apoptosis). During apoptosis, mitochondrial outer membrane permeabilization by BAX/BAK pores facilitates release of apoptotic factors, while the role of inner mitochondrial membrane (IMM) remodelling remains less understood. Here, we identify LACTB, a filament-forming serine protease and tumour suppressor, as a regulator of IMM dynamics during apoptosis. LACTB is required for apoptosis-induced IMM remodelling, which in turn causes increased release of cytochrome c and other mitochondrial apoptotic factors. LACTB-induced membrane remodelling is independent of OPA1 processing. Rather, purified LACTB binds and remodels cardiolipin-enriched membrane nanotubes preferentially over planar lipid membranes, suggesting a direct effect in apoptotic membrane remodelling. Intriguingly, LACTB is not required for mitochondrial shape changes induced by mitochondrial depolarization, suggesting that LACTB action is apoptosis-specific. Collectively, our findings establish LACTB as a mediator of apoptosis-induced IMM remodelling, suggesting a mechanism for tumour suppression in cancer.

cell biology↗

bioRxiv2022

Characterizing control of memory CD8 T cell differentiation by BTB-ZF transcription factor Zbtb20

Members of the BTB-ZF transcription factor family regulate the immune system. Our lab identified that family member Zbtb20 contributes to the differentiation, recall responses and metabolism of CD8 T cells. Here, we report a characterization of the transcriptional and epigenetic signatures controlled by Zbtb20 at single-cell resolution during the effector and memory phases of the CD8 T cell response. Without Zbtb20, transcriptional programs associated with memory CD8 T cell formation were upregulated throughout the CD8 T response. A signature of open chromatin was associated with genes controlling T cell activation, consistent with the known impact on differentiation. Additionally, memory CD8 T cells lacking Zbtb20 were characterized by open chromatin regions with overrepresentation of AP-1 transcription factor motifs and elevated RNA- and protein-level expression of the corresponding AP-1 components. Finally, we describe motifs and genomic annotations from the DNA targets of Zbtb20 in CD8 T cells identified by CUT&RUN. Together, these data establish the transcriptional and epigenetic networks contributing to the control of CD8 T cell responses by Zbtb20.

immunology↗

bioRxiv2022

Mitochondrial dysfunction triggers actin polymerization necessary for rapid glycolytic activation

Mitochondrial damage represents a dramatic change in cellular homeostasis, necessitating rapid responses. One rapid response is peri-mitochondrial actin polymerization, termed ADA (acute damage-induced actin). The consequences of ADA are not fully understood. Here we show that ADA is necessary for rapid glycolytic activation upon inhibition of mitochondrial ATP production in multiple cells, including mouse embryonic fibroblasts and effector CD8+ T lymphocytes, for which glycolysis is an important source of ATP and biosynthetic molecules. Treatments that induce ADA include CCCP, antimycin A, rotenone, oligomycin, and hypoxia. The Arp2/3 complex inhibitor CK666 or the mitochondrial sodium-calcium exchanger (NCLX) inhibitor CGP37157, applied simultaneously with the ADA stimulus, inhibit both ADA and the glycolytic increase within 5-min, suggesting that ADA is necessary for glycolytic stimulation. Two situations causing chronic reductions in mitochondrial ATP production, ethidium bromide treatment (to deplete mitochondrial DNA) and mutation to the NDUFS4 subunit of complex 1 of the electron transport chain, cause persistent peri-mitochondrial actin filaments of similar morphology to ADA. Both peri-mitochondrial actin loss and a 20% ATP decrease occur within 10 min of CK666 treatment in NDUFS4 knock-out cells. We propose that ADA is necessary for rapid glycolytic activation upon mitochondrial impairment, to re-establish ATP production.

cell biology↗

bioRxiv2019

Neuropilin-1 regulates the secondary CD8 T cell response to virus infection

Neuropilin-1 plays important roles in axonal guidance in neurons, and in the growth of new blood vessels. There is also a growing appreciation for roles played by neuropilin-1 in the immune response. This molecule is important for the function of regulatory T cells, however roles in other T cell populations have not been identified. Here we show that neuropilin-1 is expressed during the peak of the antiviral CD8 T cell response during murine gammaherpesvirus infection. Using a conditional knockout model, we deleted Nrp1 either before infection, or after CD8 T cell memory had been established. We found deletion of Nrp1 skewed the acute CD8 T cell response toward a memory precursor-like phenotype, however the ensuing resting memory response was similar regardless of Nrp1 expression. Interestingly Nrp1 deletion had differing effects on the recall response depending on the timing of deletion. When deleted before infection, Nrp1 deficiency inhibited the secondary response. Deletion just prior to re-exposure to virus lead to an enhanced secondary response. Interestingly these effects were observed only in mice infected with a persistent strain of murine gammaherpesvirus, and not a non-persistent mutant strain. These data highlight a multifaceted role for neuropilin-1 in memory CD8 T cell differentiation, dependent upon the stage of the T cell response and characteristics of the infectious agent. Several therapeutic anti-cancer therapies focus on inhibition of Nrp1 to restrict tumor growth, so knowledge of how Nrp1 blockade may affect the CD8 T cell response will provide a better understanding of treatment consequences.\n\nImportanceCD8 T cell responses are critical to control both virus infections and tumors. The ability of these cells to persist for long periods of time can result in lifelong immunity, as relatively small populations of cell can expand rapidly to counter re-exposure to the same insult. Understanding the molecules necessary for this rapid secondary expansion is critical if we are to develop therapies that can provide lifelong protection. This report shows an important and complex role for the molecule neuropilin-1 in the secondary response. Several cancer therapies targeting neuropilin-1 are in development, and this work will lead to better understanding of the effect these therapies could have upon the protective CD8 T cell response.

immunology↗