Biology subjects

Norbury, C. C.

Publications and source records attributed to Norbury, C. C..

4 recordsLinked to original sources

bioRxiv2025

A Novel Proteoglycan-4 Isoform Drives Skeletal Regeneration

Proteoglycan 4 (PRG4) is an extracellular matrix protein best known for its lubricating role in articular cartilage. Using a murine model of tibial fracture, we performed RNA-seq across multiple post-fracture timepoints and observed high Prg4 expression during the first week of healing, coinciding with the initial inflammatory phase. Single-cell RNA-seq of the fracture callus localized Prg4 expression to a stem cell population with key roles in repair. Analysis of alternative splicing in callus RNA identified a unique Prg4 isoform lacking three coding exons (hereafter termed Prg4-S). In vivo knockdown of Prg4-S using locally delivered siRNA produced multiple defects that culminated in impaired bone formation. Together, these findings uncover an unanticipated osteogenic role for a unique Prg4 splicing isoform and highlight its potential for translational applications.

molecular biology↗

bioRxiv2024

ZFAND6 is a subunit of a TRAF2-cIAP E3 ubiquitin ligase complex essential for mitophagy

The A20 ubiquitin-editing enzyme is a critical negative regulator of NF-{kappa}B signaling and inflammation. While the mechanisms by which A20 restricts inflammation have been extensively studied, the physiological functions of other A20-like proteins are largely unknown. Here, we report a previously unknown function of the A20 family member ZFAND6 as a novel regulator of mitophagy. Deletion of ZFAND6 in bone marrow-derived macrophages (BMDMs) promotes the upregulation of reactive oxygen species (ROS) and the accumulation of damaged mitochondria due to impaired mitophagy. Consequently, mitochondrial DNA (mtDNA) is released into the cytoplasm, triggering the spontaneous expression of interferon-stimulated genes (ISGs) in a cGAS-STING dependent manner, which leads to enhanced viral resistance in vitro. However, mice lacking ZFAND6 exhibit increased morbidity and mortality upon challenge with a sublethal dose of influenza A virus (IAV) due to impaired myeloid cell activation and diminished type I IFN signaling. Mechanistically, ZFAND6 bridges a TRAF2-cIAP1 interaction, which is required for the initiation of ubiquitin-dependent mitophagy. Our results suggest that ZFAND6 is a subunit of a TRAF2-cIAP E3 ligase complex that promotes the clearance of damaged mitochondria by mitophagy to maintain mitochondrial homeostasis.

immunology↗

bioRxiv2020

γδ T cells mediate a requisite portion of a wound healing response triggered by cutaneous poxvirus infection

Infection at peripheral sites, such as the skin, activates local innate immune defenses tasked with limiting spread of the pathogen while preserving tissue integrity. T cells bearing {gamma}{delta} T Cell Receptors (TCR), which comprise multiple phenotypically distinct subtypes of cells, reside in normal skin, where they shape immunity to cutaneous infection, prior to onset of an adaptive immune response by conventional {beta} CD4+ (TCD4+) and CD8+ (TCD8+) T cells. The mechanisms used by {gamma}{delta} T cells to control virus replication and tissue pathology following cutaneous infection are unknown, so we examined the role of {gamma}{delta} T cells in the response to cutaneous infection with vaccinia virus (VACV). Resident {gamma}{delta} T cells in the skin expanded and combined with recruited {gamma}{delta} T cells to control the pathology observed after cutaneous VACV infection. However, we observed no defect in control of local virus replication or increased systemic spread in mice lacking {gamma}{delta} T cells, despite induction of a cytolytic response in a specialized subset of resident {gamma}{delta} T cells. While examining {gamma}{delta} T cell-mediated control of tissue pathology following cutaneous VACV infection, we identified a unique wound healing signature associated with cutaneous virus infection that has features that are common to, but also features that antagonize, the sterile cutaneous wound healing response. Typically, tissue repair is thought to occur only after clearance of a pathogen, but the viral wound healing signature was evident prior to the peak of virus replication in the skin. Resident and recruited {gamma}{delta} T cells contributed to this wound healing signature through induction of multiple cytokines and growth factors required for efficient wound closure. Therefore, {gamma}{delta} T cells are early mediators of the wound healing response following cutaneous virus infection and are likely important in maintenance of skin barrier function and prevention of secondary bacterial infection. Author Summary{gamma}{delta} T cells resident in the skin are among the first immune cell types positioned to be able to respond to a virus infection of the skin. Therefore, it was assumed that these cells in the skin play a role similar to their role after widespread infection throughout the body, namely to kill virus infected cells and slow virus replication and spread. However, we found no role for {gamma}{delta} T cells in control of virus replication after infection of the skin. Rather, the {gamma}{delta} T cells functioned as a critical component of a previously unrecognized wound healing response that is started early after virus infection of the skin, and occurs at the same time as the immune response that aims to clear the virus. This study is the first to describe both the early wound healing response after virus infection, and the role of {gamma}{delta} T cells in that response, and this information could allow manipulation of this response to decrease secondary bacterial infection and change scarring after virus skin infections.

immunology↗

bioRxiv2019

Type I interferon-dependent CCL4 is induced by a cGAS/STING pathway that bypasses viral inhibition and protects infected tissue, independent of viral burden

Type I interferons (T1-IFN) are critical in the innate immune response, acting upon infected and uninfected cells to initiate an antiviral state by expressing genes that inhibit multiple stages of the lifecycle of many viruses. T1-IFN triggers the production of Interferon-Stimulated Genes (ISGs), activating an antiviral program that reduces virus replication. The importance of the T1-IFN response is highlighted by the evolution of viral evasion strategies to inhibit the production or action of T1-IFN in virus-infected cells. T1-IFN is produced via activation of pathogen sensors within infected cells, a process that is targeted by virus-encoded immunomodulatory molecules. This is probably best exemplified by the prototypic poxvirus, Vaccinia virus (VACV), which uses at least 6 different mechanisms to completely block the production of T1-IFN within infected cells in vitro. Yet, mice lacking aspects of T1-IFN signaling are often more susceptible to infection with many viruses, including VACV, than wild-type mice. How can these opposing findings be rationalized? The cytosolic DNA sensor cGAS has been implicated in immunity to VACV, but has yet to be linked to the production of T1-IFN in response to VACV infection. Indeed, there are two VACV-encoded proteins that effectively prevent cGAS-mediated activation of T1-IFN. We find that the majority of VACV-infected cells in vivo do not produce T1-IFN, but that a small subset of VACV-infected cells in vivo utilize cGAS to sense VACV and produce T1-IFN to protect infected mice. The protective effect of T1-IFN is not mediated via ISG-mediated control of virus replication. Rather, T1-IFN drives expression of CCL4, which recruits inflammatory monocytes that constrain the VACV lesion in a virus replication-independent manner by limiting spread within the tissue. Our findings have broad implications in our understanding of pathogen detection and viral evasion in vivo, and highlight a novel immune strategy to protect infected tissue.\n\nSummaryThe recognition of virus infection leads to a quick and robust antiviral response mediated by type I interferons (T1-IFN). Nearly all viruses have acquired genes that block the induction or action of T1-IFN in order to attain a replicative advantage. Some viruses thwart the T1-IFN response so thoroughly, that cells infected in vitro do not produce any T1-IFN. And yet, animal models with defects in T1-IFN signaling are more sensitive to infection with these viruses than their wild-type counterparts. In this study, we find evidence to explain these otherwise contradicting findings. We show that a small population of infected cells in vivo are able to utilize a pathogen-sensing pathway that is completely blocked in vitro. T1-IFN produced by these specialized cells protects mice by recruiting inflammatory monocytes that restrict the spread of virus within infected tissue, independent of viral burden. Our findings have a direct impact on our understanding of how viruses are detected in infected tissue, and present a novel strategy of the immune system to limit pathology at peripheral sites of infection.

immunology↗