Biology subjects

Morgan, E.

Publications and source records attributed to Morgan, E..

11 recordsLinked to original sources

bioRxiv2025

TOE1 influences canonical Wnt signalling in myeloid leukaemia cells through LEF-1 modulation and regulates the proliferation of haematopoietic cells through PAK2.

Acute myeloid leukaemia (AML) is an aggressive haematological malignancy characterised by the clonal proliferation of myeloid progenitor cells in the bone marrow and peripheral blood. Dysregulation of the Wnt/{beta}-catenin pathway has been implicated in the establishment and maintenance of leukaemic stem cells in AML, where higher expression of {beta}-catenin promotes clonogenic capacity, drug resistance and inferior survival. The finding that low levels of Wnt signalling are necessary to maintain normal haematopoiesis makes {beta}-catenin an attractive therapeutic target; however, drug design has been hampered by a poor understanding of its molecular interactions in leukaemia cells. To address this, we previously characterised the {beta}-catenin interactome in myeloid cells and identified a plethora of novel interacting proteins. One such interactor was Target of EGR1 (TOE1), a member of the Asp-Glu-Asp-Asp (DEDD) family of deadenylases with previously uncharacterised function in haematopoietic cells. The {beta}-catenin:TOE1 interaction was detected in the nuclear and cytosolic compartments of myeloid cell lines and primary AML samples, and {beta}-catenin depletion was found to promote the cytosolic accumulation of TOE1. Furthermore, TOE1 levels were found to be overexpressed in primary AML blasts versus normal cord-blood derived CD34+ haematopoietic stem and progenitor cells (HSPCs), suggesting that TOE1 levels may be dysregulated in leukaemia. TOE1 depletion abrogated Wnt signalling capacity (TCF/LEF activity), potentially via reduced stability/translatability of the Wnt transcription factor lymphoid enhancing factor 1 (LEF-1). TOE1 depletion further suppressed the proliferation and survival of myeloid leukaemia cell lines (HEL and OCI-AML2) and primary human CD34+ HSPC; however, this could not be fully explained through LEF-1 alone, since OCI-AML2 do not express LEF-1. Using tandem mass tag (TMT)-labelling coupled to mass spectrometry analysis in TOE1 deficient HEL and OCI-AML2 cells, we identified and validated p21 (RAC1) activated kinase 2 (PAK2) as a downregulated target that could reduce the proliferation (but not survival) of AML cell lines. Interestingly, ectopic expression of PAK2 was able to partially rescue the proliferation defect in TOE1 depleted myeloid cell lines and primary human CD34+ HSPC. In summary, these data reveal TOE1 as novel interacting partner for {beta}-catenin in haematological cells capable of modulating Wnt signalling output via LEF-1, and as a novel mediator of growth and survival in human HSPC and AML cells partly through PAK2 regulation.

cancer biology↗

bioRxiv2024

Dynamics of gut colonization by commensal and pathogenic bacteria that adhere to the intestinal epithelium

Maintaining a healthy gut microbiome plays a critical role in avoiding gut-related pathologies. Bacterial adherence to the intestinal epithelium plays a vital role in niche establishment in the gut, as in vitro experiments and mathematical modeling suggest that adherence provides a strong competitive advantage over free-floating planktonic microbes. Currently, we lack the ability to study gut microbiome adherence in an in vivo model system. Through sampling natural populations of Caenorhabditis, we discovered three bacterial species that adhere to the intestinal epithelium of several wild Caenorhabditis isolates. When transferred to C. elegans, all three bacterial species colonized the entire anterior to posterior length of the intestine lumen. We isolated these bacterial species via in vitro growth or selective enrichment in the nematode gut and identified them as Lelliottia jeotgali, Candidatus Lumenectis limosiae, and Candidatus Enterosymbion pterelaium, the latter two representing new species. Adherent Ca. L. limosiae negatively affects host fitness, while Lelliottia jeotgali and Ca. E. pterelaium exhibited a neutral effect in our assays. We demonstrated that two of these species can actively proliferate in the intestine throughout the host lifespan, with Lelliottia jeotgali colonizing throughout the lumen simultaneously and Candidatus Lumenectis limosiae showing anterior-to-posterior directionality. In competition assays, animals pre-colonized with L. jeotgali significantly reduced colonization by pathogenic Ca. L. limosiae, but this effect was not seen when animals were colonized by both bacteria simultaneously. Strikingly, regardless of the colonization paradigm, populations exposed to both bacteria showed a near-identical mitigation of the pathogenic effects of Ca. L. limosiae. Altogether, these strains illustrate the capacity of microbiome bacteria to adhere, replicate, and establish a niche across the entire intestinal lumen in C. elegans and they present an opportunity to study bacterial adherence in the context of a whole, intact and transparent animal.

microbiology↗

bioRxiv2024

Sparsity of population activity in the hippocampus is task-invariant across the tri-synaptic circuit and dorsal-ventral axis

Evidence from neurophysiological and genetic studies demonstrates that activity sparsity - the proportion of neurons that are active at a given time in a population - systematically varies across the canonical trisynaptic circuit of the hippocampus. Recent work has also shown that sparsity varies across the hippocampal dorsoventral (long) axis, wherein activity is sparser in ventral than dorsal regions. While the hippocampus has a critical role in long-term memory (LTM), whether sparsity across the trisynaptic circuit and hippocampal long axis is task-dependent or invariant remains unknown. Importantly, representational sparsity has significant implications for neural computation and theoretical models of learning and memory within and beyond the hippocampus. Here we used functional molecular imaging to quantify sparsity in the rat hippocampus during performance of the Morris water task (MWT) and contextual fear discrimination (CFD) - two popular and distinct assays of LTM. We found that activity sparsity is highly reliable across memory tasks, wherein activity increases sequentially across the trisynaptic circuit (DG < CA3 < CA1) and decreases across the long axis (ventral < dorsal). These results have important implications for models of hippocampal function and suggest that activity sparsity is a preserved property in the hippocampal system across cognitive settings.

neuroscience↗

bioRxiv2024

Breaking free from the clocks tyranny restores memory to brain damaged flies

The relationship between sleep and memory is an active topic of investigation. In this context, we demonstrate that enhancing sleep restores memory to flies with ablated Mushroom Bodies (MB), a key memory center; this is consistent across several memory assays. Mapping the underlying circuitry reveals circadian modulation of a subset of Dopaminergic neurons (DANs) that modulate aversive learning. Using imaging, we show that MB-ablation disrupts, and sleep restores the time of day these neurons are most responsive. Knocking down the receptor for the clock output signal, Pigment-dispersing factor (Pdfr), in this subset of DANs restores memory to MB-ablated flies. Crucially, MB-ablation does not result in memory impairments in the absence of a functioning clock. Our results reveal neuromodulations key role in cognitive restoration, where sleep aids memory in damaged brains, but a functioning clock unexpectedly hinders this process.

neuroscience↗

bioRxiv2023

KDM3A and KDM3B Maintain Naive Pluripotency Through the Regulation of Alternative Splicing

Histone modifying enzymes play a central role in maintaining cell identity by establishing a conducive chromatin environment for lineage specific transcription factor activity. Pluripotent embryonic stem cell (ESC) identity is characterized by a lower abundance of gene repression associated histone modifications that enables rapid response to differentiation cues. The KDM3 family of histone demethylases removes the repressive histone H3 lysine 9 dimethylation (H3K9me2). Here we uncover a surprising role for the KDM3 proteins in the maintenance of the pluripotent state through post-transcriptional regulation. We find that KDM3A and KDM3B interact with RNA processing factors such as EFTUD2 and PRMT5. Acute selective degradation of the endogenous KDM3A and KDM3B proteins resulted in altered splicing independent of H3K9me2 status or catalytic activity. These splicing changes partially resemble the splicing pattern of the more blastocyst-like ground state of pluripotency and occurred in important chromatin and transcription factors such as Dnmt3b, Tbx3 and Tcf12. Our findings reveal non-canonical roles of histone demethylating enzymes in splicing to regulate cell identity.

cell biology↗

bioRxiv2021

Transcriptome-wide Association Study and eQTL colocalization identify potentially causal genes responsible for bone mineral density GWAS associations

Genome-wide association studies (GWASs) for bone mineral density (BMD) have identified over 1,100 associations to date. However, identifying causal genes implicated by such studies has been challenging. Recent advances in the development of transcriptome reference datasets and computational approaches such as transcriptome-wide association studies (TWASs) and expression quantitative trait loci (eQTL) colocalization have proven to be informative in identifying putatively causal genes underlying GWAS associations. Here, we used TWAS/eQTL colocalization in conjunction with transcriptomic data from the Genotype-Tissue Expression (GTEx) project to identify potentially causal genes for the largest BMD GWAS performed to date. Using this approach, we identified 512 genes as significant (Bonferroni <= 0.05) using both TWAS and eQTL colocalization. This set of genes was enriched for regulators of BMD and members of bone relevant biological processes. To investigate the significance of our findings, we selected PPP6R3, the gene with the strongest support from our analysis which was not previously implicated in the regulation of BMD, for further investigation. We observed that Ppp6r3 deletion in mice decreased BMD. In this work, we provide an updated resource of putatively causal BMD genes and demonstrate that PPP6R3 is a putatively causal BMD GWAS gene. These data increase our understanding of the genetics of BMD and provide further evidence for the utility of combined TWAS/colocalization approaches in untangling the genetics of complex traits.

genomics↗

bioRxiv2021

Behaviour-driven Arc expression is greater in dorsal than ventral CA1 regardless of task or sex differences.

Evidence from genetic, behavioural, anatomical, and physiological study suggests that the hippocampus functionally differs across its longitudinal (dorsoventral or septotemporal) axis. Although, how to best characterize functional and representational differences in the hippocampus across its long axis remains unclear. While some suggest that the hippocampus can be divided into dorsal and ventral subregions that support distinct cognitive functions, others posit that these regions vary in their granularity of representation, wherein spatial-temporal resolution decreases in the ventral (temporal) direction. Importantly, the cognitive and granular hypotheses make distinct predictions on cellular recruitment dynamics under conditions when animals perform tasks with qualitatively different cognitive-behavioural demands. The cognitive function account implies that dorsal and ventral cellular recruitment differs depending on relevant behavioural demands, while the granularity account suggests similar recruitment dynamics regardless of the nature of the task performed. Here, we quantified cellular recruitment with the immediate early gene (IEG) Arc across the entire longitudinal CA1 axis in female and male rats performing spatial- and fear-guided memory tasks. Our results show that recruitment is greater in dorsal than ventral CA1 regardless of task or sex. This experimentum crucis leads to the strong inference that the granularity hypothesis for functional differences across the longitudinal axis in the rodent hippocampus is correct.

neuroscience↗

bioRxiv2020

A conserved role for sleep in supporting spatial learning in Drosophila

Sleep loss and aging impair hippocampus-dependent spatial learning in mammalian systems. Here we use the fly Drosophila melanogaster to investigate the relationship between sleep and spatial learning in healthy and impaired flies. The spatial learning assay is modeled after the Morris Water Maze. The assay uses a thermal maze consisting of a 5x5 grid of Peltier plates maintained at 36-37{degrees}C and a visual panorama. The first trial begins when a single tile that is associated with a specific visual cue is cooled to 25{degrees}C. For subsequent trials, the cold tile is heated, the visual panorama is rotated and the flies must find the new cold-tile by remembering its association with the visual cue. Significant learning was observed with two different wild-type strains - Cs and 2U, validating our design. Sleep deprivation prior to training impaired spatial learning. Learning was also impaired in the classic learning mutant rutabaga (rut); enhancing sleep restored learning to rut mutants. Further we found that flies exhibited dramatic age-dependent cognitive decline in spatial learning starting at 20-24 days of age. These impairments could be reversed by enhancing sleep. Finally, we find that spatial learning requires dopaminergic signaling and that enhancing dopaminergic signaling in aged flies restored learning. Our results are consistent with the impairments seen in rodents and humans. These results thus demonstrate a critical conserved role for sleep in supporting spatial learning, and suggest potential avenues for therapeutic intervention during aging. STATEMENT OF SIGNIFICANCEWe have studied the relationship between sleep and plasticity using a Drosophila learning assay modified after the Morris Water Maze. Using this assay, we find that sleep loss impairs spatial learning. As in mammals, flies exhibited age-dependent spatial learning impairments. Importantly, the age-dependent impairments were reversed by enhancing sleep. Interestingly, our results mirror studies on hippocampus dependent memories in rodents and humans. Thus, our data describe an evolutionarily conserved role for sleep in regulating spatial learning. They also support augmenting sleep as a therapeutic strategy to ameliorate learning impairments.

neuroscience↗

bioRxiv2019

Multiple quantitative trait loci contribute tolerance to bacterial canker incited by Pseudomonas syringae pv. actinidiae in kiwifruit (Actinidia chinensis)

Pseudomonas syringae pv. actinidiae (Psa) Biovar 3, a virulent, canker-inducing pathogen is an economic threat to the kiwifruit (Actinidia spp.) industry worldwide. The commercially grown diploid (2x) A. chinensis var. chinensis is more susceptible to Psa than tetraploid and hexaploid kiwifruit. However information on the genetic loci modulating Psa resistance in kiwifruit is not available. Here we report mapping of quantitative trait loci (QTLs) regulating tolerance to Psa in a diploid kiwifruit population, derived from a cross between an elite Psa-susceptible Hort16A and a tolerant male breeding parent P1. Using high-density genetic maps and intensive phenotyping, we identified a single QTL for Psa tolerance on Linkage Group (LG) 27 of Hort16A revealing 16-19% phenotypic variance and candidate alleles for susceptibility and tolerance at this loci. In addition, six minor QTLs were identified in P1 on distinct LGs, exerting 4-9% variance. Complete tolerance in the F1 population is attained by additive effects from Hort16A and P1 QTLs providing evidence that divergent genetic pathways fend-off virulent Psa strain. Two different bioassays further identified new QTLs for tissue-specific responses to Psa. Transcriptome analysis of Psa-tolerant and susceptible genotypes in field revealed hallmarks of basal defense and provided candidate RNA-biomarkers for screening Psa tolerance.

plant biology↗

bioRxiv2018

High-risk human papillomaviruses down-regulate expression of the Ste20 family kinase MST1 to inhibit the Hippo pathway and promote transformation

Human papillomaviruses (HPV) are a major cause of malignancy worldwide They are the aetiological agent of almost all cervical cancers and an increasing number of head and neck carcinomas. Deregulation of the Hippo pathway component YAP1 has recently been demonstrated to play a role in HPV-mediated cervical cancer, but whether other components of this pathway are implicated in the pathogenesis of this disease remains poorly understood.\n\nThe expression level and activation status of critical Hippo pathway components were analysed across multiple cytology samples from patients with cervical disease, as well as HPV positive (HPV+) and HPV negative (HPV-) cervical cancer cell lines using real time qPCR, western blot and immunohistochemistry. In parallel, we assessed the effects of MST1 and MST2 overexpression upon cervical cancer cell proliferation, migration and invasion. Finally, we interrogated the consequences of interrupted MST1 and MST2 function using a targeted small molecule inhibitor in tandem with kinase inactive MST mutants. Our analysis found that expression of the Ste20 kinase MST1 was decreased within both HPV+ primary patient samples and cervical cancer cell lines. This effect was mediated by the virus-coded oncoproteins E6 and E7, which impair MST1 transcription. Reintroduction of MST1, or its paralogue MST2, into HPV positive cervical cancer cells re-activated the Hippo pathway, leading to a reduction in cell proliferation, migration and invasion. Finally, using a small molecule inhibitor of MST1/2 or kinase inactive mutants of either protein, we demonstrated that this effect required the kinase function of MST1/2. Our results reveal that HPV down regulates MST1 expression to inactivate the Hippo pathway and so drive cells towards transformation.

microbiology↗

bioRxiv2018

A mechanistic hydro-epidemiological model of liver fluke risk

The majority of existing models for predicting disease risk in response to climate change are empirical. These models exploit correlations between historical data, rather than explicitly describing relationships between cause and response variables. Therefore, they are unsuitable for capturing impacts beyond historically observed variability and cannot be employed to assess interventions. In this study, we integrate environmental and epidemiological processes into a new mechanistic model, taking the widespread parasitic disease of fasciolosis as an example. The model simulates environmental suitability for disease transmission, explicitly linking the parasite life-cycle to key weather-water-environment conditions. First, using epidemiological data, we show that the model can reproduce observed infection levels in time and space over two case studies in the UK. Second, to overcome data limitations, we propose a calibration approach based on Monte Carlo sampling and expert opinion, which allows constraint of the model in a process-based way, including a quantification of uncertainty. Finally, comparison with information from the literature and a widely-used empirical risk index shows that the simulated disease dynamics agree with what has been traditionally observed, and that the new model gives better insight into the time-space patterns of infection, which will be valuable for decision support.

epidemiology↗