Biology subjects

Elliott, A.

Publications and source records attributed to Elliott, A..

14 recordsLinked to original sources

bioRxiv2026

Quantitative determination of longitudinal CNS cholesterol loss during myelin damage and repair

1.Cholesterol in the central nervous system (CNS) is largely unesterified (>99%) and is predominantly present in the myelin sheath ([~]70% of total CNS cholesterol). Damage to the myelin sheath can result in the conversion of cholesterol to cholesterol esters, which occurs in many neurological diseases, including multiple sclerosis. In this study, we measured longitudinal CNS free cholesterol and cholesterol ester levels in a genetic mouse model during postnatal myelination, demyelination, and remyelination using gas chromatography-mass spectrometry with single ion monitoring technique (GC-MS-SIM) and liquid chromatography mass spectrometry (LC-MS). Cholesterol levels in healthy mouse brains increased up to 38 weeks. In contrast, cholesterol in the healthy spinal cord increased during postnatal timepoints, but then remained steady out to 38 weeks. Interestingly, cholesterol esters in the spinal cord were highest at P1 and drastically reduced by P42, while the brain had similar levels during all postnatal time points. During demyelination, both brain and spinal cord cholesterol levels were significantly reduced as compared to healthy mice and failed to return to normal cholesterol levels even during remyelination. Absolute quantification of cholesterol esters during peak demyelination revealed that cholesterol esters comprise 19% of the total cholesterol pool in the brain and 65% in the spinal cord. The lack of recovery in CNS cholesterol levels after demyelination suggests that healthy de novo cholesterol synthesis pathways are disrupted in this model. Absolute quantification of CNS cholesterol is critical for revealing mechanisms of cholesterol regulation during disease and identifying targets for restoring cholesterol to promote myelin repair.

neuroscience↗

bioRxiv2026

ATM functions as a rheostat of metabolic stress in small-cell lung cancer

ATM is best known as a guardian of genomic stability, yet its contributions to oncogenic signaling in aggressive malignancies like small-cell lung cancer (SCLC) remain poorly understood. Despite ATM being an established clinical vulnerability in SCLC, its influence on dysregulated tumorigenic circuits remains unclear. We demonstrate that inhibition of ATM disrupts the AKT-mTORC1-4EBP1 signaling axis, leading to attenuation of the master regulator of stress, ATF4. ATF4 and MYC appear to co-regulate one another in a feedback loop critical for redox homeostasis. ATM inhibition perturbs both the expression and function of MYC and ATF4, leading to increased intracellular reactive oxygen species, impaired glutathione recycling, and ferroptotic cell death, thereby exposing a crucial dependency of SCLC on stress-adaptive signaling. We uncover previously unrecognized metabolic vulnerability in SCLC, nominating ATM as a regulator of adaptive stress, expanding its role beyond canonical DNA damage repair (DDR) and highlighting therapeutically exploitable opportunities in aggressive tumors. Statement of SignificanceThe metabolic landscape of SCLC remains poorly characterized, particularly its interaction with dysregulated signaling networks, limiting the development of effective strategies to overcome therapeutic resistance. Our work reveals an expanded role for ATM beyond DNA repair, positioning it as a key regulator of metabolic rewiring and highlighting new therapeutic opportunities for SCLC.

cancer biology↗

bioRxiv2025

Perturbational single-cell profiling of patient tumors defines lineage- and context-specific programs of innate immune resistance

AbstractDespite promise in preclinical models, most immuno-oncology drug candidates fail in clinical trials. These failures reflect limitations in our ability to directly model the response of human tumor and immune cells to immunotherapies. To address this gap and test the effect of innate immune agonists, we developed PERCEPT, an approach that uses ex vivo perturbational single-cell RNA sequencing to compare the response of immunomodulatory treatments with unstimulated controls directly in patient samples. Using PERCEPT, we tested cytokines and innate immune agonists in melanoma and Merkel cell carcinoma (MCC) and identified the dsRNA mimetic, RIG-I agonist, Stem Loop RNA (SLR) 14 as a powerful inducer of anti-viral states and enhancer of T cell activation. We compared transcriptional responder and non-responder patient samples and identified midkine (MDK), a multifunctional cytokine, as a potent repressor of IFN signaling in both tumor and immune cells. MDK expression dampened MHC-I presentation in human tumor cells and reduced activation of antigen-presenting cells, disrupting tumor immunity at multiple levels. In contrast to prior studies, we identified MDK as specifically enriched in neuroendocrine cancers such as MCC and small cell lung cancer compared with melanoma, suggesting the importance of lineage- and context-specific targeting. Our results demonstrate the utility of high-dimensional controlled perturbation of patient samples to identify mechanisms of innate immune response and resistance and demonstrate an actionable path towards clinical development of MDK-inhibiting therapies including FDA-approved ALK inhibitors in neuroendocrine cancers.

cancer biology↗

bioRxiv2025

ERK builds a population of short-lived nascent adhesions that produce persistent edge protrusion and cell migration

Cell migration is realized through the fast and persistent protrusion of a leading edge in the direction of movement. The actin and adhesion structures that build edge protrusions are integrated such that pro-migration signaling pathways must control both assemblies to induce protrusion. Understanding the contribution of adhesion regulation has been complicated by the inability to selectively assay the nascent adhesions that promote edge protrusion. Here, we dissect how the core RAS[->]RAF[->]MEK[->]ERK pathways control of nascent adhesions contributes to edge protrusion and cell migration by targeting an ERK FRET biosensor to adhesions and quantifying ERKs spatial and temporal activity. We find that ERK is activated in the assembling, membrane-proximal region of nascent adhesions through adhesion scaffold paxillin, which interacts with the ERK activator MEK. Tracking nascent adhesion dynamics during cell migration showed that ERK promotes both nascent adhesion assembly and disassembly to create a population of nascent adhesions with short lifetimes. MEK inhibition is partially complemented by expression of a talin R8vvv mutant that increases the nascent adhesion population, demonstrating the significance of ERKs adhesion regulation for edge protrusion and migration persistence. These findings suggest that when new adhesions initiate, the ERK activation level dictates adhesion assembly and disassembly rates to specifically build nascent adhesions that rapidly turnover, an adhesion population that promotes protrusion persistence and migration. SignificanceCell migration is essential for development, healing, and cancer spread. To move, cells need to build and break tiny structures called nascent adhesions, specifically at their edge that protrudes in the direction of movement. We discovered that ERK, a key signaling protein activated during development and cancer, helps create a fast-turning-over population of these adhesions, which supports steady movement. Using new biosensors and adhesion tracking, we showed ERK is active in the assembling part of the adhesion, where it promotes both assembly and disassembly. Increasing the nascent adhesion population helps cells move when ERK is blocked. This work reveals how ERK controls cell movement by balancing adhesion dynamics and introduces tools to study similar processes in other signaling pathways.

cell biology↗

bioRxiv2024

Basal cell of origin resolves neuroendocrine-tuft lineage plasticity in cancer

Summary paragraphNeuroendocrine and tuft cells are rare, chemosensory epithelial lineages defined by expression of ASCL1 and POU2F3 transcription factors, respectively1,2. Neuroendocrine cancers, including small cell lung cancer (SCLC), frequently display tuft-like subsets, a feature linked to poor patient outcomes3-13. The mechanisms driving neuroendocrine-tuft tumour heterogeneity, and the origins of tuft-like cancers are unknown. Using multiple genetically-engineered animal models of SCLC, we demonstrate that a basal cell of origin (but not the accepted neuroendocrine origin) generates neuroendocrine-tuft-like tumours that highly recapitulate human SCLC. Single-cell clonal analyses of basal-derived SCLC further uncovers unexpected transcriptional states and lineage trajectories underlying neuroendocrine-tuft plasticity. Uniquely in basal cells, introduction of genetic alterations enriched in human tuft-like SCLC, including high MYC, PTEN loss, and ASCL1 suppression, cooperate to promote tuft-like tumours. Transcriptomics of 944 human SCLCs reveal a basal-like subset and a tuft-ionocyte-like state that altogether demonstrate remarkable conservation between cancer states and normal basal cell injury response mechanisms14-18. Together, these data suggest that the basal cell is a plausible origin for SCLC and other neuroendocrine-tuft cancers that can explain neuroendocrine-tuft heterogeneity--offering new insights for targeting lineage plasticity.

cancer biology↗

bioRxiv2024

Gut microbial profiling of COVID-19 patients in Uganda

BackgroundWhile COVID-19 spread globally, the role of the gut microbiota in patient outcomes has remained an area of exploration especially in resource limited settings. This study aimed to comprehensively profile the gut microbiome among Ugandan COVID-19 patients and infer potential implications. MethodsNasopharyngeal swabs, stool, clinical and demographic data were collected from COVID-19 confirmed cases at the COVID-19 isolation and treatment centers in Kampala and Entebbe, Uganda, during the first and second waves of the pandemic in Uganda (i.e., 2020 and 2021, respectively). SARS-CoV-2 presence in the swab samples was confirmed by quantitative real-time RT-PCR assays. 16S rRNA metagenomic next-generation sequencing was performed on the DNA extracted from the stool samples, followed by bioinformatics analysis. Machine learning was used to determine microbes that were associated with disease severity. ResultsWe observed varied gut microbial composition between COVID-19 patients and healthy controls. Potentially pathogenic bacteria such as Klebsiella oxytoca, Salmonella enterica and Serratia marcescens had an increased presence in COVID-19 disease states, especially severe cases. Enrichment of opportunistic pathogens, such as Enterococcus species, and depletion of beneficial microbes, like Alphaproteobacteria, was observed between mild and severe cases. Machine learning identified age and microbes such as Ruminococcaceae, Bacilli, Enterobacteriales, porphyromonadaceae, and Prevotella copri as predictive of severity. ConclusionThese findings suggest that the microbiome plays a role in the dynamics of SARS-CoV-2 infection in African patients. The shift in abundance of specific microbes can moderately predict severity of COVID-19 in this population. Their direct or indirect roles in determining severity should be investigated further for potential therapeutic interventions.

bioinformatics↗

bioRxiv2024

Standardized Nomenclature and Reporting for PacBio HiFi Sequencing and Analysis of rAAV Gene Therapy Vectors

Despite recombinant adeno-associated viruses (rAAVs) being the leading platform for gene therapy, there is a lack of standardized computational analysis methods and reporting to assess the contents of each capsid through long-read sequencing. PacBios highly accurate long-read HiFi sequencing enables comprehensive characterization of AAV genomes but requires bioinformatics expertise for analyzing, interpreting and comparing the results. To address this need and improve the understanding of functional viral payloads, our working group established standardized nomenclature and reporting for long-read sequencing data of rAAV vectors. The working group recommendations cover critical quality attributes (CQAs) related to vector purity (full-length vs. fragmented genomes) and identification of contaminants (host DNA, plasmid DNA). Our data analyses of de novo manufacturing runs by the recommended protocol revealed specificity of full and partially filled capsids and high-resolution characterization of partial/truncated vector species. Finally, we provide an open-source software implementing this standardized AAV analysis and reporting to promote transparency, facilitate data comparability, and improve rAAV vector design and quality control.

bioinformatics↗

bioRxiv2023

Transcriptome analysis of peripheral blood of Schistosoma mansoni infected children from the Albert Nile region in Uganda reveals genes implicated in fibrosis pathology.

Over 290 million people are infected by schistosomes worldwide. Schistosomiasis control efforts focus on mass drug treatment with praziquantel (PZQ), a drug that kills the adult worm of all Schistosoma species. Nonetheless, re-infections have continued to be detected in endemic areas with individuals living in the same area presenting with varying infection intensities. Our objective was to characterize the transcriptome profiles in peripheral blood of children between 10 - 15 years with varying intensities of Schistosoma mansoni infection living along the Albert Nile in Uganda. RNA extracted from peripheral blood collected from 44 S. mansoni infected (34 high and 10 low by circulating anodic antigen [CAA] level) and 20 uninfected children was sequenced using Illumina NovaSeq S4 and the reads aligned to the GRCh38 human genome. Differential gene expression analysis was done using DESeq2 and enriched pathways in differentially expressed genes (DEGs) were identified using REACTOME. Principal component analysis revealed clustering of gene expression by gender when S. mansoni infected children were compared with uninfected children. In addition, we identified 14 DEGs between S. mansoni infected and uninfected individuals, 56 DEGs between children with high infection intensity and uninfected individuals, 33 DEGs between those with high infection intensity and low infection intensity and no DEGs between those with low infection and uninfected individuals. We also observed upregulation and downregulation of some DEGs that are associated with fibrosis and its regulation. These data suggest expression of fibrosis associated genes as well as genes that regulate fibrosis in S. mansoni infection. The relatively few significant DEGS observed in children with schistosomiasis suggests that chronic S. mansoni infection is a stealth infection that does not stimulate a strong immune response. Author SummarySchistosomiasis is a neglected tropical disease transmitted via an intermediate snail host through contact with contaminated fresh water. Even with routine Mass Drug Administration for treatment of the infection, re-infections are still common and variations in infection intensity and pathology are still observed in individuals in the same location. These may be due to differences in individuals response to S. mansoni infection. In this study, we used RNAseq to identify differentially expressed genes associated with S. mansoni infection in children between 10-15 years. We conducted comparisons between phenotypes including infection intensities measured by circulating anodic antigen, wasting by body mass index and stunting by height-for-age z score. Our data showed very low numbers of significant differentially expressed genes in all comparisons. Some of the few differentially expressed genes that were observed were associated with fibrosis which is the cause of pathology in humans and has been observed in late stages of S. mansoni infection in murine studies.

genomics↗

bioRxiv2022

Genome-wide analysis of Schistosoma mansoni reveals population structure and praziquantel drug selection pressure within Ugandan hot-spot communities

Populations within schistosomiasis control areas, especially those in Africa, are recommended to receive regular mass drug administration (MDA) with praziquantel (PZQ) as the main strategy for controlling the disease. The impact of PZQ treatment on schistosome genetics remains poorly understood, and is limited by a lack of high-resolution genetic data on the population structure of parasites within these control areas. We generated whole-genome sequence data from 174 individual miracidia collected from both children and adults from fishing communities on islands in Lake Victoria in Uganda that had received either annual or quarterly MDA with PZQ over four years, including samples collected immediately before and four weeks after treatment. Genome variation within and between samples was characterised and we investigated genomic signatures of natural selection acting on these populations that could be due to PZQ treatment. The parasite population on these islands was more diverse than found in nearby villages on the lake shore. We saw little or no genetic differentiation between villages, or between the groups of villages with different treatment intensity, but slightly higher genetic diversity within the pre-treatment compared to post-treatment parasite populations. We identified classes of genes significantly enriched within regions of the genome with evidence of recent positive selection among post-treatment and intensively treated parasite populations. The differential selection observed in post-treatment and pre-treatment parasite populations could be linked to any reduced susceptibility of parasites to praziquantel treatment. Author summarySchistosomiasis is caused by parasitic helminths of the genus Schistosoma. Schistosoma mansoni is the primary cause of intestinal schistosomiasis, a devastating and widespread parasitic infection that causes morbidity, death and socio-economic impact on endemic communities across the world and especially sub-Saharan Africa. Using whole-genome sequencing, we were able to elucidate the parasite population within Lake Victoria island fishing communities in Uganda which are among the major hotspots for schistosomiasis. We further assessed genetic markers that might be linked to recent observations concerning reduced susceptibility to praziquantel, the major drug used in the treatment of this disease. Whole-genome data on the population genetics of S. mansoni in an African setting will provide a strong basis for future functional genomics or transcriptomic studies that will be key to identifying drug targets, improving existing drugs or developing new therapeutic interventions.

genomics↗

bioRxiv2021

Behavior emerges from unstructured muscle activity in response to neuromodulation

Identifying neural substrates of behavior requires defining actions in terms that map onto brain activity. Brain and muscle activity naturally correlate via the output of motor neurons, but apart from simple movements it has been difficult to define behavior in terms of muscle contractions. By mapping the musculature of the pupal fruit fly and comprehensively imaging muscle activation at single cell resolution, we here describe a multiphasic behavioral sequence in Drosophila. Our characterization identifies a previously undescribed behavioral phase and permits extraction of major movements by a convolutional neural network. We deconstruct movements into a syllabary of co-active muscles and identify specific syllables that are sensitive to neuromodulatory manipulations. We find that muscle activity shows considerable variability, which reduces upon neuromodulation. Our work provides a platform for studying whole-animal behavior, quantifying its variability across multiple spatiotemporal scales, and analyzing its neuromodulatory regulation at cellular resolution.

neuroscience↗

bioRxiv2020

An efficient and accurate frailty model approach for genome-wide survival association analysis controlling for population structure and relatedness in large-scale biobanks

With decades of electronic health records linked to genetic data, large biobanks provide unprecedented opportunities for systematically understanding the genetics of the natural history of complex diseases. Genome-wide survival association analysis can identify genetic variants associated with ages of onset, disease progression and lifespan. We developed an efficient and accurate frailty (random effects) model approach for genome-wide survival association analysis of censored time-to-event (TTE) phenotypes in large biobanks by accounting for both population structure and relatedness. Our method utilizes state-of-the-art optimization strategies to reduce the computational cost. The saddlepoint approximation is used to allow for analysis of heavily censored phenotypes (>90%) and low frequency variants (down to minor allele count 20). We demonstrated the performance of our method through extensive simulation studies and analysis of five TTE phenotypes, including lifespan, with heavy censoring rates (90.9% to 99.8%) on ~400,000 UK Biobank participants with white British ancestry and ~180,000 samples in FinnGen, respectively. We further performed genome-wide association analysis for 871 TTE phenotypes in UK Biobank and presented the genome-wide scale phenome-wide association (PheWAS) results with the PheWeb browser.

genomics↗

bioRxiv2019

When polymorphism and monomorphism meet: discordant genomic and phenotypic clines across a lizard contact zone

Colour polymorphism can promote rapid evolution and speciation, particularly when populations differ in the number or composition of morphs. The contact zone between Ctenophorus modestus (swift dragon) and C. decresii (tawny dragon) is a compelling study system in which to examine evolutionary processes and outcomes when polymorphic and monomorphic populations meet. Ctenophorus modestus is polymorphic for male throat coloration and lacks ultraviolet (UV) reflectance while C. decresii is monomorphic with UV-blue throats. We characterised genomic and phenotypic clines across the contact zone based on single nucleotide polymorphisms, the mitochondrial ND4 gene, and male colour traits, and concurrently assessed the phenotype of captive-bred F1 hybrids. Our results indicate that genomic introgression is asymmetric, with high frequencies of backcrossing to C. modestus but not C. decresii, accompanied by the prevalence of the C. modestus mtDNA haplotype in hybrids. The clines for throat phenotype are abrupt and displaced towards the range of C. decresii, relative to the genetic and dorsolateral phenotype clines. By contrast, both throat and dorsolateral phenotypes in captive-bred F1 hybrids are intermediate. Our results are consistent with the hypothesis that throat coloration, a polymorphic sexual signal in C. modestus, is the target of selection during incipient speciation and provide insight into the microevolutionary processes that may link polymorphism and speciation.

evolutionary biology↗

bioRxiv2019

Mycobacterium tuberculosis infection boosts B cell responses to unrelated pathogens

Antigens from Mycobacterium tuberculosis (M.tb), have been shown to stimulate human B cell responses to unrelated recall antigens in vitro. However, it is not known whether natural M.tb infection or whether vaccination with the related species, Mycobacterium bovis BCG, has a similar effect. This study investigated the effects of M.tb infection and BCG vaccination on B cell responses to heterologous pathogen recall antigens. Antibodies against several bacterial and viral pathogens were quantified by ELISA in 68 uninfected controls, 62 individuals with latent TB infection (LTBI) and 107 active pulmonary TB (APTB) cases, and 24 recently BCG-vaccinated adolescents and naive controls. Antibody avidity was investigated using surface plasmon resonance and B cell ELISPOT assays were used to measure plasmablast and memory B cell responses (MBC) in APTB cases and healthy donor controls. APTB was associated with higher levels of antibodies to tetanus toxoid (TT), diphtheria toxoid, respiratory syncytial virus, measles virus and Kaposis sarcoma herpesvirus, compared to uninfected controls. Vaccination with BCG did not alter levels of antibodies against heterologous pathogens. TT-specific antibody avidity was increased in APTB and the ratio of TT-specific plasmablasts to MBCs in the APTB cases was 7:1. M.tb infection boosts serological memory to heterologous pathogens in human subjects and this process may be driven by polyclonal activation of memory B cells.\n\nSignificanceMycobacterium tuberculosis (M.tb) has potent immunostimulatory properties and has been used in adjuvant preparations to improve vaccine responses in animals. This study shows that natural M.tb infection in humans is associated with increased antibody and B cell recall responses to heterologous pathogens. This data suggests a potential role for M.tb antigens in immunotherapies designed to maintain antibody immunity to diverse infections.

immunology↗

bioRxiv2017

Multifactorial Chromosomal Variants Regulate Polymyxin Resistance In Extensively Drug-Resistant Klebsiella pneumoniae

Extensively drug-resistant Klebsiella pneumoniae (XDR-KP) infections cause high mortality and are disseminating globally. Identifying the genetic basis underpinning resistance allows for rapid diagnosis and treatment. XDR isolates sourced from Greece and Brazil, including nineteen polymyxin-resistant and five polymyxin-susceptible strains, underwent whole genome sequencing. Approximately 90% of polymyxin resistance was enabled by alterations upstream or within mgrB. The most common mutation identified was an insertion at nucleotide position 75 in mgrB via an ISKpn26-like element in the ST258 lineage and ISKpn13 in one ST11 isolate. Three strains acquired an IS1 element upstream of mgrB and another strain had an ISKpn25 insertion at 133 bp. Other isolates had truncations (C28STOP, Q30STOP) or a missense mutation (D31E) affecting mgrB. Complementation assays revealed all mgrB perturbations contributed to resistance. Missense mutations in phoQ (T281M, G385C) were also found to facilitate resistance. Several variants in phoPQ co-segregating with the ISKpn26-like insertion were identified as potential partial suppressor mutations. Three ST258 samples were found to contain subpopulations with different resistance conferring mutations, including the ISKpn26-like insertion colonising with a novel mutation in pmrB (P158R), both confirmed via complementation assays. We also characterized a new multi-drug resistant Klebsiella quasipneumoniae strain ST2401 which was susceptible to polymyxins. These findings highlight the broad spectrum of chromosomal modifications which can facilitate and regulate resistance against polymyxins in K. pneumoniae.\n\nDATA SUMMARYO_LIWhole genome sequencing of the 24 clinical isolates has been deposited under BioProject PRJNA307517 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA307517).\nC_LI\n\nIMPACT STATEMENTKlebsiella pneumoniae contributes to a high abundance of nosocomial infections and the rapid emergence of antimicrobial resistance hinders treatment. Polymyxins are predominantly utilized to treat multidrug-resistant infections, however, resistance to the polymyxins is arising. This increasing prevalence in polymyxin resistance is evident especially in Greece and Brazil. Identifying the genomic variations conferring resistance in clinical isolates from these regions assists with potentially detecting novel alterations and tracing the spread of particular strains. This study commonly found mutations in the gene mgrB, the negative regulator of PhoPQ, known to cause resistance in KP. In the remaining isolates, missense mutations in phoQ were accountable for resistance. Multiple novel mutations were detected to be segregating with mgrB perturbations. This was either due to a mixed heterogeneous sample of two polymyxin-resistant strains, or because of multiple mutations within the same strain. Of interest was the validation of novel mutations inphoPQ segregating with a previously known ISKpn26-like element in disrupted mgrB isolates. Complementation of these phoPQ mutations revealed a reduction in minimum inhibitory concentrations and suggests the first evidence of partial suppressor mutations in KP. This research builds upon our current understanding of heteroresistance, lineage specific mutations and regulatory variations relating to polymyxin resistance.

microbiology↗