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Foster, L.

Publications and source records attributed to Foster, L..

At least 19 recordsLinked to original sources

Interactome-based deep learning and path-level decomposition reveal TGFβ-IFNα competition in MASH

Dysregulated signaling drives Metabolic Dysfunction-Associated Steatohepatitis (MASH) through a complex crosstalk between pro- and anti-fibrotic cues. We previously observed potential competition between IFN-mediated JAK-STAT signaling and TGF{beta} in modulating MASH fibrosis, but the precise mechanism of that competition, and whether it can act directly on hepatocytes, is yet unknown. We used DT-LEMBAS, an interactome-based deep learning framework, training an ensemble of 50 models on drug-induced transcriptomics from primary human hepatocytes. The ensemble captured transcriptional changes induced by simulated receptor knockouts and aligned predicted profiles with known TGF{beta}- and IFN-induced phenotypes. Systematic simulations demonstrate their competitive modulation of MASH phenotype scores benchmarked against human cohorts. To extract mechanistic insights, we developed a gradient-based approach, where we computed the Jacobian of the used recurrent signaling network and applied chain rule decomposition to identify a four-node module of SMAD3, TP63, STAT2, and STAT3. Mechanistic hypotheses involving these canonical and non-canonical TF mediators were experimentally validated in primary hepatocyte spheroids. This work establishes a generalizable and scalable approach to decode large signaling neural networks into interpretable biological subnetworks.

systems biology↗

TransPepMS: A Tool to Verify Peptides Absent from Reference Proteomes

Cells generate peptides absent from reference proteomes, including products of reverse proteolysis and gene fusions. These are an increasingly pursued class of targets in autoimmune disease, cancer vaccines and T-cell therapies. The sequence is itself the discovery, yet a convincing spectral match does not establish it, because an ordinary genome-encoded peptide of the same mass can explain the spectrum equally well. Independent benchmarking has identified this ambiguity as a dominant source of error in reported non-canonical identifications. Here, we introduce TransPepMS, which adjudicates each proposed assignment and returns a verdict of retained, unresolved, or rejected. For example, on adjudicating 1,154 reported proteasome-spliced immunopeptides, only 53 survived same-mass competition, whereas 91 of 99 insulin-spike hybrids were retained and all 46 planted canonical peptides were rejected, showing that TransPepMS discriminates genuine non-canonical peptides rather than merely deflating claims. TransPepMS provides peptide validation before they guide biological interpretation and immune-target selection.

biochemistry↗

Effects of cholinergic potentiation on resting-state functional connectivity in healthy adults

Acetylcholine is a key attentional neuromodulator, yet its effects on large-scale organisation of resting-state networks remain poorly understood. Here, we investigated whether acute cholinergic potentiation with the acetylcholinesterase inhibitor donepezil modulates functional connectivity within and between resting-state networks involved in attention. Nineteen healthy young adults completed a double-blind, placebo-controlled crossover study using 7T resting-state functional MRI (rs-fMRI), with imaging performed before and after administration of donepezil or placebo. We tested whether donepezil altered functional connectivity within and between the dorsal attention, ventral attention, default mode, and frontoparietal networks and whether it improved attentional orienting in the same volunteers. Voxel-wise analysis revealed a significant donepezil-related increase in dorsal attention network connectivity within the left inferior parietal cortex. We did not observe donepezil-related changes within the ventral attention, default mode, or frontoparietal networks. Network-level analyses did not identify significant global changes in network strength. Exploratory analyses indicated reduced coupling between the dorsal attention and default mode networks following donepezil relative to placebo, although this result did not survive correction for multiple comparisons. Donepezil did not significantly improve attentional orienting at the group level. However, exploratory analyses suggested that greater donepezil-related enhancement of functional connectivity within the identified left inferior parietal cluster was associated with greater improvement in attentional orienting. These findings suggest that acute cholinergic potentiation does not globally enhance resting-state connectivity across attentional networks in healthy young adults. Instead, donepezil may selectively modulate localised dorsal attention network circuitry, particularly within left inferior parietal cortex, a region implicated in sensory integration and externally oriented cognition.

neuroscience↗

A Globally Representative Immunopeptidomics Approach to Identify Population-Wide Vaccine Candidates

Vaccine development has historically relied on preclinical testing using one or two cell lines, typically of Caucasian descent, contributing to vaccines that may fail to provide adequate protection across genetically diverse populations. A major factor in these failures is the lack of consideration for human leukocyte antigen (HLA) diversity, with over 30,000 HLA alleles worldwide exhibiting distinct frequencies across ethnic groups and geographic regions. Here, we present a globally representative immunopeptidomics approach that addresses HLA diversity at the earliest stages of vaccine antigen discovery. We established a panel of 30 cell lines from the 1000 Genomes Project that represent 75% of the worlds most common HLA alleles. Using a combined computational and experimental approach, we identified 18 common binding motifs (7 MHC class I and 11 MHC class II) shared across 24 cell lines from the panel. We developed an accessible bioinformatic tool that predicts globally presentable antigenic regions from any pathogen proteome by identifying peptides matching these common binding motifs. Validation with Salmonella enterica serovar Typhimurium and SARS-CoV-2 Spike protein demonstrated that our method successfully identifies known immunogenic regions, with experimentally detected epitopes showing substantial overlap with predicted regions of interest. Notably, only three cell lines were required to validate highly immunogenic S. enterica targets, including OmpC--a porin with known 100% protective efficacy--detected across all tested lines. Our approach enables researchers to rapidly screen pathogen proteomes using freely available bioinformatic tools, with optional experimental validation requiring minimal resources. By identifying antigens with broad population coverage before clinical trials begin, this method has the potential to increase vaccine success rates while ensuring equitable protection across diverse populations. The cell line panel, common binding motifs, and bioinformatic workflow are publicly available, providing an accessible pathway for developing vaccines that truly serve global populations.

immunology↗

Evaluating a structured expert elicitation approach for adaptive conservation: Lessons from five years in practice

Threatened species management relies on Ex ante estimates of species responses to different interventions to generate meaningful predictions. Structured expert elicitation is often used to generate these estimates, but comparisons of these expert-predicted outcomes with observed results are rare. This study aims to evaluate the utility of expert elicitation for adaptive management in the New South Wales Saving our Species (SoS) program in Australia by revisiting six species management plans that were generated from bespoke structured elicitation guidelines five years prior. Each species management plan included a defined scope, conceptual model, monitoring indicators and estimated response to management curves under different scenarios. Experts reviewed the conceptual models after five years of management and monitoring and compared the predicted response to management with observed monitoring data. In three of the six case studies, observed outcomes closely matched predictions. Where predictions diverged, factors such as unanticipated new threats and unexpected responses to interventions contributed to discrepancies. However, in all cases, the structured approach provided a clear logic for planning, enabling managers to systematically refine their understanding. The conceptual models and response curves proved valuable for collaboration, communication, and generating hypotheses for unexpected results. This work demonstrates the value of the bespoke guidelines in supporting adaptive management processes, strengthening the knowledge base for threatened species conservation while improving alignment between predictions and real-world outcomes.

ecology↗

Ribosome biogenesis mediates the translational increase of non-optimal codon transcripts during IFN stimulation

The interferon response is a signaling pathway unique to vertebrates that links the innate and adaptive immune responses. Interferons signal through a cascade of factors including the JAK-STAT pathway to induce the transcription of hundreds of interferon-stimulated genes (ISGs). Although the main interferon signal transduction pathways and ISGs have been elucidated, translational regulation of ISG transcripts is not fully understood. Prior work demonstrated that ribosomal protein RPL28 negatively regulates a subset of ISGs; however, we find that this effect may be due to a reduction in overall ribosome availability. Multi-omics analysis of RNA-seq and LC-MS/MS data reveal proteins, including several ISGs, that are translationally up-regulated in IFN-{beta}-stimulated cells depleted of ribosome biogeneis factor BOP1. Analysis of codon usage demonstrates a significant reduction in codon optimality for proteins that are translationally up-regulated during BOP1 knockdown and IFN-{beta} stimulation. Using reporter constructs, we demonstrate that codon non-optimal reporters are translated more than codon-optimized reporters in BOP1-depleted IFN-{beta} cells. We propose that ribosome biogenesis regulates translational fine-tuning of integral protein production to ensure optimal interferon responses.

systems biology↗

Dynamics of Bacterial and Viral Transmission in Experimental Microbiota Transplantation

Mouse models are vital tools for discerning the relative contributions of host and microbial genetics to disease, often requiring the transplantation of microbiota between different mouse strains. Transfer methods include antibiotic treatment of recipients and colonization using either co-housing with donors or the transplantation of fecal or cecal donor material. However, the efficiency and dynamics of these methods in reconstituting recipients with donor microbes is not well understood. We thus directly compared co-housing, fecal transplantation, and cecal transplantation methods. Donor mice from Taconic Biosciences, possessing distinct microbial communities, served as the microbial source for recipient mice from Jackson Laboratories, which were treated with antibiotics to disrupt their native microbiota. We monitored bacterial and viral populations longitudinally over the course of antibiotics treatment and reconstitution using 16S rRNA gene sequencing, quantitative PCR, and shotgun sequencing of viral-like particles. As expected, antibiotic treatment rapidly depleted microbial biomass and diversity, with slow and incomplete natural recovery of the microbiota in non-transplanted control mice. While all transfer methods reconstituted recipient mice with donor microbiota, co-housing achieved this more rapidly for both bacterial and viral communities. This study provides valuable insights into microbial transfer methods, enhancing reproducibility and informing best practices for microbiota transplantation in mouse models.

microbiology↗

The neonatal Fc receptor and DPP4 are human astrovirus receptors

Human astroviruses (HAstV) are major global causes of gastroenteritis, but little is known about host factors required for their cellular entry. Here, we utilized complementary CRISPR-Cas9-based knockout and activation screening approaches and identified neonatal Fc receptor (FcRn) and dipeptidyl-peptidase IV (DPP4) as entry factors for HAstV infection of human intestinal epithelial cells. Disruption of FcRn or DPP4 reduced HAstV infection in permissive cells and, reciprocally, overexpression of these factors in non-permissive cells was sufficient to promote infection. We observed direct binding between FcRn and HAstV virions as well as purified spike protein. Finally, inhibitors for DPP4 and FcRn currently in clinical use prevent HAstV infection in cell lines and primary human enteroids. Thus, our results reveal mechanisms of HAstV entry as well as druggable targets. One-Sentence SummaryTargeting FcRn or DPP4 using available therapies effectively prevents human astrovirus infection in human enteroid cultures.

microbiology↗

Common viral infections inhibit egg laying in honey bee queens and are linked to premature supersedure

With their long lives and extreme reproductive output, social insect queens have escaped the classic trade-off between fecundity and lifespan but evidence for a trade-off between fecundity and immunity has been inconclusive. This is in part because pathogenic effects are seldom decoupled from effects of immune induction. We conducted parallel, blind virus infection experiments in the laboratory and in the field to interrogate the idea of a reproductive immunity trade-off and better understand how these ubiquitous honey bee stressors affect queen health. We found that queens injected with infectious virus had smaller ovaries and were less likely to recommence egg-laying than controls, while queens injected with UV-inactivated virus displayed an intermediate phenotype. In the field, heavily infected queens had smaller ovaries and infection was a meaningful predictor of whether supersedure cells were observed in the colony. Immune responses in queens receiving live virus were similar to queens receiving inactivated virus, and several of the same immune proteins were negatively associated with ovary mass in the field. This work solidifies the relationship between virus infection and symptoms associated with queen failure and suggests that a reproductive-immunity trade-off is partially, but not wholly responsible for these effects.

zoology↗

β-Hydroxybutyrate promotes basal insulin secretion while decreasing glucagon secretion in mouse and human islets.

Dietary carbohydrates raise blood glucose and limiting carbohydrate intake improves glycemia in patients with type 2 diabetes. Low carbohydrate intake (< 25 g) allows the body to utilize fat as its primary fuel. As a consequence of increased fatty acid oxidation, the liver produces ketones to serve as an alternative energy source. {beta}-Hydroxybutyrate ({beta}HB) is the most abundant ketone. While {beta}HB has a wide range of functions outside of the pancreas, its direct effects on islet cell function remain understudied. We examined human islet secretory response to acute racemic {beta}HB treatment and observed increased insulin secretion at low glucose concentrations (3 mM glucose). Because {beta}HB is a chiral molecule, existing as both R and S forms, we further studied insulin and glucagon secretion following acute treatment with individual {beta}HB enantiomers in human and C57BL6/J mouse islets. We found that acute treatment with R-{beta}HB increased insulin secretion and decreased glucagon secretion at physiological glucose concentrations in both human and mouse islets. Proteomic analysis of human islets treated with R-{beta}HB over 72 h showed altered abundance of proteins that may promote islet cell health and survival. Collectively, our data show that physiological concentrations of {beta}HB influence hormone secretion and signaling within pancreatic islets.

cell biology↗

Testing Adaptive Therapy Protocols using Gemcitabine and Capecitabine on a Mouse Model of Endocrine-Resistant Breast Cancer

Highly effective cancer therapies often face limitations due to acquired resistance and toxicity. Adaptive therapy, an ecologically inspired approach, seeks to control therapeutic resistance and minimize toxicity by leveraging competitive interactions between drug-sensitive and drug-resistant subclones, prioritizing patient survival and quality of life over maximum cell kill. In preparation for a clinical trial in breast cancer, we used large populations of MCF7 cells to rapidly generate endocrine-resistance breast cancer cell line. We then mimicked second line therapy in ER+ breast cancers by treating the endocrine-resistant MCF7 cells in a mouse xenograft model to test adaptive therapy with capecitabine, gemcitabine, or the combination of those two drugs. Dose-modulation adaptive therapy with capecitabine alone increased survival time relative to MTD, but not statistically significant (HR: 0.22, 95% CI 0.043-1.1 P = 0.065). However, when we alternated the drugs in both dose modulation (HR = 0.11, 95% CI: 0.024 - 0.55, P = 0.007) and intermittent adaptive therapies significantly increased survival time compared to high dose combination therapy (HR = 0.07, 95% CI: 0.013 - 0.42; P = 0.003). Overall, survival time increased with reduced dose for both single drugs (P < 0.01) and combined drugs (P < 0.001). Adaptive therapy protocols resulted in tumors with lower proportions of proliferating cells (P = 0.0026) and more apoptotic cells (P = 0.045). The results show that Adaptive therapy outperforms high-dose therapy in controlling endocrine-resistant breast cancer, favoring slower-growing tumors, and showing promise in two-drug alternating regimens.

cancer biology↗

Sequential early-life viral infections modulate the microbiota and adaptive immune responses to systemic and mucosal vaccination

Increasing evidence points to the microbial exposome as a critical factor in maturing and shaping the host immune system, thereby influencing responses to immune challenges such as infections or vaccines. To investigate the effect of early-life viral exposures on immune development and vaccine responses, we inoculated mice with six distinct viral pathogens in sequence beginning in the neonatal period, and then evaluated their immune signatures before and after intramuscular or intranasal vaccination against SARS-CoV-2. Sequential viral infection drove profound changes in all aspects of the immune system, including increasing circulating leukocytes, altering innate and adaptive immune cell lineages in tissues, and markedly influencing serum cytokine and total antibody levels. Beyond these immune responses changes, these exposures also modulated the composition of the endogenous intestinal microbiota. Although sequentially-infected mice exhibited increased systemic immune activation and T cell responses after intramuscular and intranasal SARS-CoV-2 immunization, we observed decreased vaccine-induced antibody responses in these animals. These results suggest that early-life viral exposures are sufficient to diminish antibody responses to vaccination in mice, and highlight their potential importance of considering prior microbial exposures when investigating vaccine responses.

microbiology↗

Exit of spore dormancy transforms the yeast cytoplasm and the solubility of its proteome

The biophysical properties of the cytoplasm are major determinants of key cellular processes and adaptation. Many yeasts produce dormant spores that can withstand extreme conditions. We show that spores of Saccharomyces cerevisiae exhibit extraordinary biophysical properties, including a highly viscous and acidic cytosol. These conditions alter the solubility of more than 100 proteins such as metabolic enzymes that become more soluble as spores transit to active cell proliferation upon nutrient repletion. A key regulator of this transition is the heat shock protein Hsp42, which shows transient solubilization and phosphorylation, and is essential for the transformation of the cytoplasm during germination. Germinating spores therefore return to growth through the dissolution of protein assemblies, orchestrated in part by Hsp42 activity. The modulation of spores molecular properties are likely key adaptive features of their exceptional survival capacities.

cell biology↗

Identification of unusually disulphide-bonded insulin forms using mass spectrometry and thermolysin cleavage

Insulin is an essential hormone made by the pancreatic beta-cells in the islets of Langerhans. Beta-cells produce more insulin protein than virtually all other cellular proteins combined. Dysfunction in the process of insulin synthesis can lead to disease, including rare forms of monogenic diabetes. Specifically, aberrant intra-insulin and inter-insulin disulphide bonds have been implicated in the pathology of type 1 diabetes and type 2 diabetes, respectively. In type 1 diabetes, misprocessed insulin isoforms may be neoepitopes that kick-start and/or exacerbate the auto-immune response. In type 2 diabetes, aberrant disulphides form insulin dimers that can clog the endoplasmic reticulum and contribute to beta cell dysfunction. To facilitate the study of novel and known insulin neoepitopes and dimers, we present an unbiased and rapid technique for identifying insulin disulphide patterns from pancreatic islet extracts. The basis of this method is the cleavage between insulins cysteine residues with the metalloprotease, thermolysin, and subsequent identification of cysteine containing fragments and their partner peptides by LC-MS/MS. Using this technique, we identify 6 aberrant disulphide bonded insulin species, including a previously described type 1 diabetes neoepitope, as well as inter-chain disulphide bonded insulin dimers. Furthermore, using the endoplasmic stress inducer, thapsigargin, we observe increased disulphide errors in a patient donor sample. This approach lays foundations to identify the scope and cause of aberrant insulin disulphide formation in health and disease.

molecular biology↗

Drone honey bees (Apis mellifera) are disproportionately sensitive to abiotic stressors despite expressing high levels of stress response proteins

Drone honey bees (haploid males) are the obligate sexual partners of queens, and the availability of healthy, high-quality drones directly affects a queens fecundity and productivity of her subsequent colony. Yet, our understanding of how stressors affect drone fecundity and physiology is presently limited. We investigated sex biases in susceptibility to abiotic stressors (cold stress, topical imidacloprid exposure, and topical exposure to a realistic cocktail of pesticides), and we found that drones were more sensitive to cold and imidacloprid exposure but the cocktail was not toxic at the concentrations tested. We corroborated this lack of apparent toxicity with in-hive cocktail exposures via pollen feeding. We then used quantitative proteomics to investigate protein expression profiles in the hemolymph of topically exposed workers and drones, and we show that drones express surprisingly high levels of putative stress response proteins relative to workers. Drones apparently invest in strong constitutive expression of damage-mitigating proteins for a wide range of stressors, yet they are still sensitive to stress when challenged. The robust expression of stress-response proteins suggests that drone stress tolerance systems are fundamentally rewired relative to workers, and their susceptibility to stress depends on more than simply gene dose or deleterious recessive alleles.

cell biology↗

Insulin-dependent and -independent dynamics of insulin receptor trafficking in muscle cells

Insulin resistance contributes to type 2 diabetes and can be driven by hyperinsulinemia. Insulin receptor (INSR) internalization and cell-surface dynamics at rest and during insulin exposure are incompletely understood in muscle cells. Using surface labelling and live-cell imaging, we observed robust basal internalization of INSR in C2C12 myoblasts, without an effect of added insulin. Mass-spectrometry using INSR knockout cells as controls, identified high-confidence binding partners, including proteins associated with internalization. We confirmed known interactors, including IGF1R, but also identified underappreciated INSR-binding factors such as ANXA2. AlphaFold-Multimer analysis of these INSR-binding proteins predicted potential INSR binding sites of these proteins. Protein-protein interaction network mapping suggested links between INSR and caveolin-mediated endocytosis. INSR interacted with both caveolin and clathrin heavy chain (CLTC) in mouse skeletal muscle and C2C12 myoblasts. Whole cell 2D super-resolution imaging revealed that high levels of insulin (20 nM) increased INSR colocalization with CAV1 but decreased its colocalization with CLTC. Single particle tracking confirmed the colocalization of cell-surface INSR with both over-expressed CAV1-mRFP and CLTC-mRFP. INSR tracks that colocalized with CAV1 exhibited longer radii and lifetimes, regardless of insulin exposure, compared to non-colocalized tracks, whereas insulin further increased the lifetime of INSR/CLTC colocalized tracks. Overall, these data suggest that muscle cells utilize both CAV1 and CLTC-dependent pathways for INSR dynamics and internalization.

cell biology↗

Cryptic costs of viral infection in a model social insect

Declining insect populations emphasize the importance of understanding the drivers underlying reductions in insect fitness. Here, we investigated viruses as a threat to social insect reproduction, using honey bees as a model species. We report that in a sample of N = 93 honey bee (Apis mellifera) queens from nine beekeeping operations across a wide geographic range, high levels of natural viral infection are associated with decreased ovary mass. We confirmed this finding in an independent sample of N = 54 queens. Failed (poor quality) queens displayed higher levels of viral infection, reduced sperm viability, smaller ovaries, and altered ovary protein composition compared to healthy queens. We experimentally infected queens with Israeli acute paralysis virus (IAPV) and found that the ovary masses of IAPV-injected queens were significantly smaller than control queens, demonstrating a causal relationship between viral infection and ovary size. Queens injected with IAPV also had significantly lower expression of vitellogenin, the main source of nutrition deposited into developing oocytes, and higher levels of heat-shock proteins (HSPs), which are part of the honey bees antiviral response. This work together shows that viral infections occurring naturally in the field are compromising queen reproductive success.

systems biology↗

Honey bee queen health is unaffected by contact exposure to pesticides commonly found in beeswax

Honey bee queen health is crucial for colony health and productivity, and pesticides have been previously associated with queen loss and premature supersedure. Prior research has investigated the effects of indirect pesticide exposure on queens via workers, as well as direct effects on queens during development. However, as adults, queens are in constant contact with wax as they walk on comb and lay eggs; therefore, direct pesticide contact with adult queens is a relevant but seldom investigated exposure route. Here, we conducted laboratory and field experiments to investigate the impacts of topical pesticide exposure on adult queens. We tested dose-response relationships of six pesticides commonly found in wax: coumaphos, tau-fluvalinate, atrazine, 2,4-DMPF, chlorpyriphos, chlorothalonil, and a cocktail of all six, each dosed up to 32 times the concentrations typically found in wax. We found no effect of any treatment on queen mass or sperm viability. Furthermore, none of the 1,568 proteins quantified in the queens fat bodies (a major site of detoxification enzyme production) were differentially expressed. In a field trial with N = 30 queens exposed to either a handling control, a solvent control, or a pesticide cocktail, we again found no impact on queen egg-laying pattern, mass, or emergence mass of daughter workers. Further, of the 3,127 proteins identified in fluid from the spermatheca (sperm storage organ), none were differentially expressed. These experiments consistently show that at realistic exposure levels, pesticides commonly found in wax have no direct impact on queen performance, reproduction, or quality metrics. We suggest that previously reported associations between high levels of pesticide residues in wax and queen failure are most likely driven by indirect effects of worker exposure (either through wax or other hive products) on queen care or queen perception.

pharmacology and toxicology↗