Biology subjects

Burgess, D.

Publications and source records attributed to Burgess, D..

9 recordsLinked to original sources

bioRxiv2026

Examining the impact of the Chlamydia muridarum-induced synthesis of IFN-β during genital tract infection

Chlamydia trachomatis infection of the female genital tract can result in severe reproductive sequelae, including pelvic inflammatory disease, tubal scarring, and infertility. Type I interferons have been implicated in both host defense and immunopathogenesis during chlamydial infection, with conflicting conclusions across experimental systems. However, the specific contributions of individual interferon subtypes remain poorly defined. Here, we examined the role of interferon beta (IFN-{beta}) in regulating epithelial immune responses and intracellular bacterial development during Chlamydia muridarum infection. Using murine oviduct epithelial (OE) cell lines derived from wild-type, IFN{beta}-deficient, and Toll-like receptor 3 (TLR3)-deficient mice, we demonstrate that IFN-{beta} is a critical epithelial-intrinsic mediator of host defense. Loss of IFN-{beta} led to dysregulation of genes associated with inflammation, immune regulation, and fibrosis, altered chlamydial inclusion morphology, enhanced expression of bacterial genes throughout the chlamydial developmental cycle, and increased chlamydial replication. Importantly, exogenous IFN-{beta} restored both immune mediator production and bacterial control during IFN{beta}-deficiency. Parallel analyses revealed that TLR3 deficiency phenocopied IFN-{beta} loss, supporting a TLR3-IFN-{beta} signaling axis that restricts chlamydial growth. Consistent with these in vitro findings, IFN{beta}-deficient mice exhibited enhanced bacterial burden during genital tract infection. Together, these data establish IFN-{beta} as a protective epithelial mediator during chlamydial infection and demonstrate that type I interferon responses are not functionally uniform. Our findings provide a mechanistic framework to reconcile the protective role of IFN-{beta} with reports of reduced pathology in interferon-/{beta} receptor-deficient models and highlight the importance of dissecting individual interferon pathways in chlamydial immunopathogenesis. ImportanceGenital tract infection with Chlamydia trachomatis remains a leading cause of preventable infertility worldwide. Although type I interferons are widely viewed as contributors to chlamydial pathology, most studies have examined global interferon signaling rather than the roles of individual interferon subtypes. In this study, we demonstrate that interferon beta (IFN-{beta}) plays a protective, epithelial-intrinsic role during chlamydial infection by restricting bacterial development and shaping local immune responses. These findings challenge the prevailing view that type I interferons are uniformly detrimental in this setting and reveal that distinct interferon subtypes can exert opposing effects on host defense and disease outcome. By defining a TLR3-IFN-{beta} signaling axis that limits chlamydial replication, this work advances our understanding of epithelial immunity in the female genital tract and has important implications for the design of targeted immunomodulatory strategies to prevent chlamydia-induced reproductive pathology.

microbiology↗

bioRxiv2026

Interferon-β Coordinates Epithelial Immune Networks and Fibrotic Responses During Chlamydia muridarum Infection

Chlamydia trachomatis infection is the most common bacterial sexually transmitted infection worldwide and a leading cause of inflammatory reproductive tract disease and infertility in women. Much of the tissue damage associated with genital chlamydial infection arises from host inflammatory responses rather than direct bacterial cytotoxicity. Epithelial cells lining the female reproductive tract represent the primary host cells infected during chlamydial infection and play key roles in initiating innate immune responses. Among the cytokines produced by infected epithelial cells, type-I interferons have emerged as important regulators of host defense and inflammatory signaling; however, the specific contribution of interferon-{beta} (IFN-{beta}) to epithelial transcriptional responses during chlamydial infection remains incompletely defined. In the present study, we investigated the role of IFN-{beta} in coordinating epithelial immune signaling networks during infection with Chlamydia muridarum. Using wild-type murine oviduct epithelial cells (OE-WT) and IFN-{beta}-deficient epithelial cells (OE-IFN{beta}-KO), we performed pathway-focused RT{superscript 2} Profiler PCR array analyses examining transcriptional responses across four biological pathways: (1) innate and adaptive immune responses, (2) type-I interferon signaling, (3) inflammatory and autoimmune responses, and (4) fibrosis-associated pathways. Infection of OE-WT cells resulted in coordinated induction of cytokines, chemokines, and interferon-stimulated genes associated with antimicrobial defense and immune cell recruitment. In contrast, IFN-{beta} deficiency resulted in widespread dysregulation of these transcriptional programs, including reduced induction of interferon-responsive chemokines such as CCL5 and CXCL10, altered inflammatory cytokine expression, and transcriptional signatures consistent with enhanced tissue remodeling responses. Notably, IFN-{beta} deficiency resulted in increased TNF expression accompanied by reduced IL-6 induction, suggesting disruption of balanced inflammatory signaling networks. Pathway analyses further revealed dysregulated expression of fibrosis-associated genes including Serpine1, Ctgf, and Eng in IFN-{beta}-deficient epithelial cells, indicating potential mechanisms linking interferon signaling to tissue remodeling during infection. Collectively, these findings identify IFN-{beta} as a central regulator of epithelial immune networks during chlamydial infection and suggest that disruption of IFN-{beta} signaling may promote inflammatory and fibrotic pathology within the female reproductive tract. Author SummarySexually transmitted infections caused by Chlamydia trachomatis are a major cause of infertility worldwide. Although antibiotic treatment can eliminate the bacteria, damage to the reproductive tract often results from the bodys own immune response to infection. The epithelial cells lining the reproductive tract are the first cells infected and play an important role in initiating immune responses. In this study, we investigated how a specific immune signaling molecule, interferon-{beta} (IFN-{beta}), regulates the gene expression programs activated in epithelial cells during chlamydial infection. Using pathway-focused gene expression arrays, we found that IFN-{beta} coordinates multiple immune pathways, including interferon signaling, inflammatory cytokine networks, and genes associated with tissue remodeling. When IFN-{beta} was absent, many of these pathways became dysregulated, resulting in altered inflammatory signaling and gene expression patterns linked to fibrosis. These findings suggest that IFN-{beta} functions as a key regulator that helps balance protective immune responses with inflammatory processes that can damage reproductive tissues during infection.

microbiology↗

bioRxiv2026

Mechanisms of disrupted neurodevelopment after Zika virus infection in infancy

Congenital and early-life Zika virus (ZIKV) infection can result in neurologic deficits. Precise mechanisms of injury, especially in the more subtle presentation of postnatal infection, are not fully elucidated. Here, we defined the effects of ZIKV on the developing brain using single cell transcriptomics, histopathology and design-based stereology, diffusion MRI, and neurobehavioral assessments in infant rhesus macaques. ZIKV upregulated interferon-stimulated genes in activated microglia and cell death pathways in neurons and downregulated metabolism and differentiation genes in mature oligodendrocytes. Abnormal micro-organization of the corpus collosum and limbic white matter tracts was seen on diffusion weighted imaging. A curated gene set associated with autism spectrum disorder risk was negatively enriched in inhibitory and excitatory neurons from ZIKV-infected infants, with increased emotional reactivity already evident two weeks following infection. From single cells to organism-level behaviors, these results define the pathways and processes disrupted by early-life ZIKV infection.

neuroscience↗

bioRxiv2023

Feeding Behavior Modifies Daily Rhythms in Autonomic Signaling and Core Body Temperature to Shape 24-hour Rhythms in Cardiac Electrophysiology

Rhythmic feeding behavior is critical for regulating the phase and amplitude in the {asymp}24-hour variation of the heart rate (RR intervals), ventricular repolarization (QT intervals), and core body temperature in mice. We hypothesized the changes in cardiac electrophysiology associated with feeding behavior were secondary to changes in core body temperature. Telemetry was used to record electrocardiograms and core body temperature in mice during ad libitum-fed conditions and after inverting normal feeding behavior by restricting food access to the light cycle. Light cycle-restricted feeding quickly modified the phase and amplitude of the 24-hour rhythms in RR intervals, QT intervals, and core body temperature to realign with the new feeding time. Heart rate variability analysis and inhibiting {beta}-adrenergic and muscarinic receptors suggested that the changes in the phase and amplitude of the 24-hour rhythms in RR intervals were secondary to changes in autonomic signaling. In contrast, the changes in the QT intervals closely mirrored changes in core body temperature. Studies at thermoneutrality confirmed the daily variation in the QT interval, but not the RR interval, and reflected daily changes in core body temperature (even in ad libitum-fed conditions). Correcting the QT interval for differences in core body temperature helped to unmask QT interval prolongation after starting light cycle-restricted feeding and in a mouse model of long QT syndrome. We conclude feeding behavior alters autonomic signaling and core body temperature to regulate the phase and amplitude in RR and QT intervals, respectively.

physiology↗

bioRxiv2023

Reduction of cortical pulling at mitotic entry facilitates aster centration

Although it has been studied for more than a century, the question of how one cell divides into two equal parts is still not fully resolved. Zygotes have provided much of the mechanistic insight into how the mitotic apparatus finds the center of the cell since the centrally-located mitotic apparatus is created from a large sperm aster that forms at the cortex and thus far from the zygote center. Here we show that in ascidians, the sperm aster extends throughout the cytoplasm during interphase yet remains located near the cortex and does not migrate towards the zygote center. It is only at mitotic entry, when the sperm aster has duplicated and the mitotic apparatus is being assembled, that most of the migration and centration occurs. This temporal pattern of centration behavior is mirrored by primate zygotes (including human). The current mechanisms of aster centration include cytoplasmic pulling that scale with microtubule (MT) length, MT pushing against the proximal cortex or MT-based cortical pulling. However, it is not yet known whether and how these 3 mechanisms are coordinated to prevent aster migration during interphase and trigger migration at mitotic entry. By monitoring quantitatively all three mechanisms (cytoplasmic pulling, pushing and cortical pulling) we have discovered that cortical pulling is switched off as the zygote enters mitosis while both cytoplasmic pulling and proximal cortical pushing remain active. Physical simulations could recapitulate both the static and migratory aspects of sperm aster and mitotic apparatus behavior. We therefore surmise that the reduction in cortical pulling at mitotic entry represents a switch that allows proximal cortical pushing forces and cytoplasmic pulling forces to center the nascent mitotic apparatus. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=156 SRC="FIGDIR/small/533625v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@135189dorg.highwire.dtl.DTLVardef@e2ef1dorg.highwire.dtl.DTLVardef@c070f7org.highwire.dtl.DTLVardef@38832f_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISperm aster/mitotic apparatus centration occurs at entry into first mitosis C_LIO_LIMT-based cortical pulling is active during interphase and switched off at mitotic entry C_LIO_LILoss of cortical pulling at mitosis entry facilitates centration of the aster C_LIO_LIMT-based cytoplasmic pulling is active during both interphase and mitosis C_LIO_LIAgent-based simulations advocate the need for cytoplasmic pulling, a switch in cortical pulling and a minor role of pushing for aster centration at mitotic entry. C_LI

cell biology↗

bioRxiv2021

Ovule siRNAs methylate and silence protein-coding genes in trans

24-nt small interfering siRNAs maintain asymmetric DNA methylation at thousands of euchromatic transposable elements in plant genomes in a process call RNA-directed DNA Methylation (RdDM). RdDM is dispensable for growth and development in Arabidopsis, but is required for reproduction in other plant species, such as Brassica rapa. 24-nt siRNAs are particularly abundant in maternal reproductive tissue, due largely to overwhelming expression from a small number of loci in the ovule and developing seed coat, termed siren loci. Recently it was shown that abundantly expressed 24-nt siRNAs produced in the tapetal tissue of anthers can methylate male meiocyte genes in trans (Long et al., 2021). Here we show that a similar process takes place in female tissue. siRNAs are produced from gene fragments embedded in some siren loci, and these siRNAs can trigger methylation in trans at related protein-coding genes. This trans-methylation is associated with silencing of some target genes and may be responsible for seed abortion in RdDM mutants. Furthermore, we demonstrate that a consensus sequence in at least two families of DNA transposons is associated with abundant siren expression, most likely through recruitment of the CLSY3 putative chromatin remodeller. This research describes a new mechanism whereby RdDM influences gene expression and sheds light on the role of RdDM during plant reproduction.

plant biology↗

bioRxiv2020

Silencing of Mu elements in maize involves distinct populations of small RNAs and distinct patterns of DNA methylation

Epigenetic changes involve changes in gene expression that can be heritably transmitted to daughter cells in the absence of changes in DNA sequence. Epigenetics has been implicated in phenomena as diverse as development, stress response and carcinogenesis. A significant challenge facing those interested in investigating epigenetic phenomena is determining causal relationships between DNA methylation, specific classes of small RNAs and associated changes in gene expression. Because they are the primary targets of epigenetic silencing in plants and, when active, are often targeted for de novo silencing, transposable elements (TEs) represent a valuable source of information about these relationships. We use a naturally occurring system in which a single TE can be heritably silenced by a single derivative of that TE. By using this system it is possible to unravel causal relationships between different size classes of small RNAs, patterns of DNA methylation and heritable silencing. Here, we show that the long terminal inverted repeats (TIRs) within Zea mays MuDR transposons are targeted by distinct classes of small RNAs during epigenetic silencing that are dependent on distinct silencing pathways. Further, these small RNAs target distinct regions of the TIRs, resulting in different patterns of cytosine methylation with different functional consequences with respect to epigenetic silencing and heritability of that silencing. SummaryTransposable elements (TEs) are a ubiquitous feature of plant genomes. Because of the threat they post to genome integrity, most TEs are epigenetically silenced. However, even closely related plant species often have dramatically different populations of TEs, suggesting periodic rounds of activity and silencing. Here we show that the process of de novo methylation of an active element in maize involves two distinct pathways, one of which is directly implicated in causing epigenetic silencing and one of which is the result of that silencing.

genetics↗

bioRxiv2017

Role of midbody remnant in meiosis II creating tethered polar bodies

Polar body (PB) formation is an extreme form of unequal cell division that occurs in oocytes due to the eccentric position of the small meiotic spindle near the oocyte cortex. Prior to PB formation, a chromatin-centered process causes the cortex overlying the meiotic chromosomes to become polarized. This polarized cortical subdomain marks the site where a cortical protrusion or outpocket forms at the oocyte surface creating the future PBs. We observed that PB1 becomes tethered to the egg via PB2, indicating that the site of PB1 cytokinesis directed the precise site for PB2 emission. We therefore studied whether the midbody remnant left behind following PB1 emission was involved, together with the egg chromatin, in defining the precise cortical site for PB2 emission. During outpocketing of PB2 in ascidians, we discovered that a small corps around 1m in diameter protruded from the center of the cortical outpocket that will form the future PB2, which we call the \"polar corps\". During emission of PB2, this small polar corps became localized between PB2 and PB1 and appeared to link PB2 to PB1. We tested the hypothesis that this small polar corps on the surface of the forming PB2 was the midbody remnant from the previous round of PB1 cytokinesis. We had previously discovered that Plk1::Ven labeled midbody remnants in ascidian embryos. We therefore used Plk1::Ven to follow the dynamics of the PB1 midbody remnant during meiosis II. Plk1::Ven strongly labeled the small polar corps that formed on the surface of the cortical outpocket that created PB2. Following emission of PB2, this polar corps was rich in Plk1::Ven and linked PB2 to PB1. By labelling actin (with LifeAct::mCherry/GFP or TRITC-Phalloidin) we also demonstrated that actin accumulates at the midbody remnant and also forms a cortical cap around the midbody remnant in meiosis II that prefigured the precise site of cortical outpocketing during PB2 emission. Phalloidin staining of actin and immunolabelling of anti-phospho aPKC during meiosis II in eggs that had PB1 removed showed that the midbody remnant remained within the egg following emission of PB1. Dynamic imaging of microtubules labelled with Ens::3GFP, MAP7::GFP or EB3::3GFP showed that one pole of the second meiotic spindle was located near the midbody remnant while the other pole rotated away from the cortex during outpocketing. Finally, we report that failure of the second meiotic spindle to rotate can lead to the formation of two cortical outpockets at anaphase II, one above each set of chromatids. It is not known whether the midbody remnant of PB1 is involved in directing the precise location of PB2 in other species as in ascidians. However, a review of the literature indicates that PB1 is tethered to the egg surface via PB2 in a number of species including members of the cnidarians, lophotrochozoa and echinoids, suggesting that the midbody remnant formed during PB1 emission may be involved in directing the precise site of PB2 emission throughout the invertebrates.

developmental biology↗

bioRxiv2017

Kif2 microtubule depolymerase is required for unequal cell division and localizes to a subdomain of cortical endoplasmic reticulum

Unequal cell division (UCD) is a fundamental process responsible for creating sibling cell size asymmetry; however, how microtubules are specifically depolymerized on one aster of the mitotic spindle creating a smaller sibling cell during UCD has remained elusive. Using invertebrate chordate embryos (ascidian) that possess a large cortical structure (CAB) that causes UCD, we identified a microtubule depolymerase (Kif2) involved in creating cell size asymmetry. Kif2 localizes to the cortical subdomain of endoplasmic reticulum in the CAB. During three successive UCDs, Kif2 protein accumulates at the CAB during interphase and is delocalized from the CAB in mid mitosis. Rapid imaging of microtubule dynamics at the cortex revealed that microtubules do not penetrate the CAB during interphase. Inhibition of Kif2 function prevents the development of mitotic aster asymmetry and centrosome movement towards the CAB thereby blocking UCD, whereas locally increasing microtubule depolymerization causes exaggerated asymmetric spindle positioning. This study provides insights into the fundamental process of UCD and for the first time shows that a microtubule depolymerase is localized to a cortical site controlling UCD.

cell biology↗