Biology subjects

Curtis, A. M.

Publications and source records attributed to Curtis, A. M..

5 recordsLinked to original sources

bioRxiv2025

Cis-regulatory variation in ISOCHORISMATE SYNTHASE 1 modulates systemic salicylic acid biosynthesis and systemic acquired resistance in plants

Systemic acquired resistance (SAR) is a long-distance immune response that protects uninfected plant tissues following a localized pathogen attack. In the model plant Arabidopsis thaliana, SAR depends on the systemic accumulation of salicylic acid (SA), mediated by the transcription factor CCA1 HIKING EXPEDITION (CHE), which activates the SA biosynthetic gene ISOCHORISMATE SYNTHASE1 (ICS1). However, the conservation and functional significance of the CHE-ICS1 regulatory module across plant species remain poorly understood, particularly in the Brassicaceae, where ICS1 is the major contributor to SA biosynthesis among two known pathways: the ICS1 and PHENYLALANINE AMMONIA-LYASE (PAL) routes. Here, we identify natural variation in cis-regulatory elements within the ICS1 promoter that affects CHE binding across species. In multiple Brassicaceae species with divergent cis-element sequences, CHE fails to regulate ICS1, leading to the absence of systemic ICS1 induction and SA accumulation following pathogen infection. Despite this deficiency, SAR still occurs in these species, albeit to a lesser extent than in species with successful systemic induction of SA mediated by an intact CHE-ICS1 regulatory module. Interestingly, introducing the CHE-ICS1 module into species lacking this interaction confers systemic SA accumulation, highlighting the potential to enhance systemic immunity through cis-element modification. Our findings demonstrate that sequence variation in a cis-regulatory element underlies the interspecies diversification of SAR regulatory mechanisms and highlight the evolutionary plasticity of plant immune signaling. This study provides a molecular framework for engineering enhanced systemic immunity in crops, particularly within the Brassicaceae, through the targeted modification of cis-regulatory elements that regulate SA biosynthesis.

plant biology↗

bioRxiv2024

Trained Immunity Causes Myeloid Cell Hypercoagulability

Venous thromboembolism is common in individuals with chronic inflammatory diseases, but the pathogenic basis for this increased thrombotic risk remains poorly understood. Myeloid cell trained immunity describes persistent innate immune cell memory arising from prior exposure to an inflammatory stimulus, leading to an enhanced immune response to subsequent unrelated stimuli. We identify enhanced myeloid cell prothrombotic activity as a novel maladaptive consequence of trained immunity. LPS stimulation of murine bone marrow-derived macrophages trained previously with either {beta}-glucan or free haem exhibited significantly enhanced procoagulant and antifibrinolytic gene expression and activity compared to macrophages stimulated with LPS alone. The {beta}-glucan training-mediated increase in activated myeloid cell procoagulant activity was mediated by enhanced acid sphingomyelinase-mediated tissue factor (TF) functional decryption. Furthermore, pre-treatment with methyltransferase and acetyltransferase inhibitors to erase epigenetic marks associated with innate immune memory diminished trained macrophage TF gene expression in {beta}-glucan-trained macrophages. Functional analysis of splenic monocytes isolated from {beta}-glucan-trained mice revealed enhanced procoagulant activity up to 4 weeks after {beta}-glucan administration compared to monocytes from control mice over the same time period. Remarkably, monocyte procoagulant activity increased proportionately with time since {beta}-glucan administration, before plateauing at 4 weeks. Furthermore, haematopoietic progenitor cells and bone marrow interstitial fluid isolated from {beta}-glucan-trained mice possessed enhanced procoagulant activity compared to control mice. Trained immunity and associated metabolic perturbations may therefore represent novel therapeutic vulnerabilities in immunothrombotic disease development, opening new avenues for targeted intervention.

immunology↗

bioRxiv2024

EPILEPTOGENESIS INHIBITS THE CIRCADIAN CLOCK AND RESHAPES THE DIURNAL TRANSCRIPTOMIC RHYTHMICITY IN THE MOUSE HIPPOCAMPUS

Epileptogenesis is the process that leads the brain into epileptic activity. Clinical evidence shows that [~]90% of people with epilepsy present rhythmicity in the timing of their seizures presentation. However, whether the circadian clock is a key player during epileptogenesis remains unknown. Here, we triggered epileptogenesis in mice by the intra-amygdala injection of kainic acid and profiled by RNA sequencing their hippocampal diurnal mRNA rhythmicity. We show that epileptogenesis largely reshapes the hippocampal transcriptomic rhythmicity and that the molecular clock machinery is inhibited due to the disruption of the core clock gene Bmal1. We identified relevant dysregulated pathways and their dynamics in epileptogenesis, predicting a key role for microglial-driven neuroinflammation. We predicted the genes that Bmal1 is directly controlling over time. Finally, we sought for translational relevance evidence by performing RNA sequencing in hippocampal samples resected from patients with mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE-HS) and cross-analyzing datasets.

neuroscience↗

bioRxiv2023

GLYCOLYTIC REPROGRAMMING FUELS MYELOID CELL-DRIVEN HYPERCOAGULABILITY

BackgroundMyeloid cell metabolic reprogramming is a hallmark of inflammatory disease, however, its role in inflammation-induced hypercoagulability is poorly understood. Objective/MethodsUsing novel myeloid cell-based global haemostasis assays and murine models of immunometabolic disease, we evaluated the role of inflammation-associated metabolic reprogramming in regulating blood coagulation. ResultsGlycolysis was essential for enhanced activated myeloid cell tissue factor expression and decryption, driving increased cell-dependent thrombin generation in response to inflammatory challenge. Similarly, inhibition of glycolysis enhanced activated macrophage fibrinolytic activity via reduced plasminogen activator inhibitor 1 (PAI-1)-activity. Macrophage polarisation or activation markedly increased endothelial protein C receptor (EPCR) expression on monocytes and macrophages, leading to increased myeloid cell-dependent protein C activation. Importantly, inflammation-dependent EPCR expression on tissue-resident macrophages was also observed in vivo. Adipose tissue macrophages from obese mice fed a high-fat diet exhibited significantly enhanced EPCR expression and APC generation compared to macrophages isolated from the adipose tissue of healthy mice. Similarly, the induction of colitis in mice prompted infiltration of EPCR+ innate myeloid cells within inflamed colonic tissue that were absent from the intestinal tissue of healthy mice. ConclusionCollectively, this study identifies immunometabolic regulation of myeloid cell hypercoagulability, opening new therapeutic possibilities for targeted mitigation of thrombo-inflammatory disease. ESSENTIALSO_LIInflammation-mediated glycolytic reprogramming enables myeloid cell-induced hypercoagulability and antifibrinolytic activity. C_LIO_LI2-Deoxy-D-glucose (2-DG) inhibits the expression of transcription factors necessary for inflammation-induced procoagulant gene expression. C_LIO_LIMyeloid cell membrane regulation of tissue factor procoagulant activity is glycolysis-dependent. C_LIO_LIActivation of myeloid innate immunity dysregulates activated protein C anticoagulant pathway activity. C_LI

immunology↗

bioRxiv2020

Post-Transcriptional Circadian Regulation in Macrophages Organizes Temporally Distinct Immunometabolic States

Our core timekeeping mechanism, the circadian clock, regulates an astonishing amount of cellular physiology and behavior, playing a vital role in organismal fitness. While the mechanics of circadian control over cellular regulation can in part be explained by the transcriptional activation stemming from the positive arm of the clocks transcription-translation negative feedback loop, research has shown that extensive circadian regulation occurs beyond transcriptional activation in fungal species and data suggest that this post-transcriptional regulation may also be preserved in mammals. To determine the extent to which circadian output is regulated post-transcriptionally in mammalian cells, we comprehensively profiled the transcriptome and proteome of murine bone marrow-derived macrophages in a high resolution, sample rich time course. We found that only 15% of the circadian proteome had corresponding oscillating mRNA and this regulation was cell intrinsic. Ontological analysis of oscillating proteins revealed robust temporal enrichment for protein degradation and translation, providing potential insights into the source of this extensive post-transcriptional regulation. We noted post-transcriptional temporal-gating across a number of connected metabolic pathways. This temporal metabolic regulation further corresponded with rhythms we observed in ATP production, mitochondrial morphology, and phagocytosis. With the strong interconnection between cellular metabolic states and macrophage phenotypes/responses, our work demonstrates that post-transcriptional circadian regulation in macrophages is broadly utilized as a tool to confer time-dependent immune function and responses. As macrophages coordinate many immunological and inflammatory functions, an understanding of this regulation provides a framework to determine the impact of circadian regulation on a wide array of disease pathologies.

molecular biology↗