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Ellis, C.

Publications and source records attributed to Ellis, C..

17 recordsLinked to original sources

Resampling-based validation of a SNP panel for hybrid detection across generations: a case study in European lobster

Accurate detection of hybridization and introgression is critical for both evolutionary research and applied conservation. In many systems, however, hybrid ancestry is difficult to detect beyond the F1 generation, especially when based on limited genetic markers. In European waters, hybridization between the native Homarus gammarus and the invasive H. americanus poses a direct risk to the integrity of native stocks and effective fishery management, yet detection methods are often limited to morphological traits or first-generation hybrids. A set of 79 SNPs previously developed to distinguish species between American and European lobsters and F1 individuals has shown promise, but its capacity to resolve later-generation backcrosses remains untested. Here, we present a resampling-based evaluation of this panels performance under realistic introgression scenarios, using individual-based population genetic models informed by empirical data. We show that the panel retains discriminatory power across multiple hybrid classes, with diminishing accuracy in second-generation backcrosses. These findings validate the panels utility for applied monitoring and highlight the broader potential of resumpling-anchored frameworks to benchmark hybrid detection tools in a wide range of species. Article summaryThis study tests how well a reduced panel of genetic markers can detect hybridization across multiple generations. Using empirical genetic data of a 79-SNP panel from European and American lobsters, the authors generated individuals with known ancestry proportions through a resampling framework that preserves observed genetic variation. These data were analysed using model-based genetic assignment and ordination. The results show that the marker panel reliably identifies pure species and first-generation hybrids, but has reduced power to distinguish later backcross generations, mainly between adjacent hybrid classes. The study provides a practical benchmark for evaluating reduced marker panels used in applied monitoring and conservation genetics.

genomics↗

Neuronal APOE4 reduction with an APOE-I3-targeting ASO protects against neurodegeneration and neuroinflammation in an Alzheimer's disease mouse model

Apolipoprotein E4 (APOE4) is the strongest genetic risk factor for late-onset Alzheimers disease (AD). Within the central nervous system (CNS), APOE is produced by a variety of cell types, with differential roles in AD pathogenesis. Studies have shown that APOE4 produced by neurons plays a central role in promoting the development of major AD pathologies, including p-tau accumulation, neuroinflammation, and neurodegeneration, highlighting its role as an upstream initiating factor that affects other cell types and downstream AD-related pathologies. Here, we demonstrate that antisense oligonucleotides (ASOs) targeting APOE-I3, a neuron-specific splicing variant of APOE mRNA, effectively reduce APOE expression in neurons in vitro and in vivo. Treating PS19 tauopathy mice expressing APOE4 with this APOE-I3-targeting ASO reduces neuronal APOE4, rescues neurodegeneration, and diminishes neuroinflammation. Strikingly, the extent of neuronal APOE4 reduction predicts the efficacy of rescuing neurodegeneration. Single nucleus RNA-sequencing demonstrated that APOE-I3-targeting ASO treatment decreases disease associated neuronal and glial subtypes and increases a disease-protective microglial subtype. These findings suggest that preferential knockdown of neuronal APOE4 with an APOE-I3-targeting ASO protects against key hallmarks of AD pathology, elucidating a potential therapeutic approach for treating APOE4-driven AD.

neuroscience↗

Neuronal APOE4 drives damaging lipid accumulation via contact-dependent neuron-oligodendrocyte-microglia interaction in Alzheimer's disease

Apolipoprotein E4 (APOE4) confers the greatest genetic risk for developing Alzheimers disease (AD). With APOE4 broadly expressed in the brain, its cell-type-specific roles in AD pathogenesis are only beginning to be defined. Here, we show that neuronal APOE4 expression drives damaging lipid accumulation in hippocampal neurons, oligodendrocytes, and microglia, with preferential buildup of peroxidized lipids in microglia in a tauopathy mouse model. Neuron-specific removal of APOE4 abolished this lipid phenotype, whereas neuron-specific expression of APOE4 was sufficient to recapitulate it, demonstrating that neuronal APOE4 is both necessary and sufficient for lipid accumulation. Strikingly, the association between lipid burden, microgliosis, and neurodegeneration was strongest in mice with neuron-specific APOE4 expression. Single-nucleus RNA sequencing revealed neuronal APOE4-vulnerable neuron populations, as well as enrichment of disease-associated microglia and oligodendrocytes, all promoting lipid pathology. Primary mouse co-culture experiments showed that neuronal APOE4 drives microglial lipid accumulation via contact-dependent mechanisms involving uptake of lipids from neurons and oligodendrocytes. These findings establish neuronal APOE4 as a key driver of lipid accumulation via neuron-oligodendrocyte-microglia interactions, providing mechanistic insight into APOE4-driven lipid pathology in AD.

neuroscience↗

Neuronal APOE4 alone is sufficient to drive tau pathology, neurodegeneration, and neuroinflammation in an Alzheimer's disease mouse model

Apolipoprotein E4 (APOE4), the strongest genetic risk factor for late-onset Alzheimers disease (AD), exacerbates tau tangles, amyloid plaques, neurodegeneration, and neuroinflammation--the pathological hallmarks of AD. While astrocytes are the primary producers of APOE in the CNS, neurons increase APOE expression under stress and aging. Prior work established that neuronal APOE4 is essential for AD pathogenesis, but whether it is sufficient to drive disease remained unknown. We generated a PS19 tauopathy mouse model selectively expressing APOE4 in neurons. Neuronal APOE4 alone proved sufficient to promote pathological tau accumulation and propagation, neurodegeneration, and neuroinflammation to levels comparable to a tauopathy model with human APOE4 knocked-in globally. Single-nucleus RNA sequencing further revealed similar transcriptomic changes in neurons and glia of both models. Together, these findings demonstrate that neuronal APOE4 alone can initiate and propagate AD pathologies, underscoring its pivotal role in disease pathogenesis and its potential as a therapeutic target.

neuroscience↗

Intelectin-2 is a broad-spectrum antimicrobial lectin

Mammals regulate the localization, composition, and activity of their native microbiota at colonization sites. Lectins residing at these sites influence microbial populations, but their individual functions are often unclear. Intelectins are found in chordates at mucosal barriers, but their functions are not well characterized. We found that mouse intelectin-2 (mItln2) and human intelectin-2 (hItln2) engage and crosslink mucins via carbohydrate recognition. Moreover, both lectins recognize microbes within native microbial communities, including gram-positive and gram-negative isolates from the respiratory and gastrointestinal tracts. This ability to engage mammalian and microbial glycans arises from calcium-coordinated binding of carbohydrate residues within mucus and microbial surfaces. Microbes, but not human cells, bound by mItln2 or hItln2, suffer a loss of viability. These findings underscore the crucial antimicrobial role of mammalian intelectin-2 in mucosal defense, where it plays offensive (microbial killing) and defensive (mucus crosslinking) roles in regulating microbial colonization.

microbiology↗

Leveraging the genetic diversity of trout in the rivers of the British Isles and northern France to understand the movements of sea trout (Salmo trutta L.) around the English Channel

Populations of anadromous brown trout, also known as sea trout, have suffered recent marked declines in abundance due to multiple factors, including climate change and human activities. While much is known about their freshwater phase, less is known about the species marine feeding migrations. This situation is hindering the effective management and conservation of anadromous trout in the marine environment. Using a panel of 95 single nucleotide polymorphism markers we developed a genetic baseline, which demonstrated strong regional structuring of genetic diversity in trout populations around the English Channel and adjacent waters. Extensive baseline testing showed this structuring allowed high-confidence assignment of known-origin individuals to region of origin. This study presents new data on the movements of anadromous trout in the English Channel and southern North Sea. Assignment of anadromous trout sampled from 12 marine and estuarine localities highlighted contrasting results for these areas. The majority of these fisheries are composed predominately of stocks local to the sampling location. However, there were multiple cases of long-distance movements of anadromous trout, with several individuals originating from rivers in northeast England being caught in the English Channel and southern North Sea, in some cases more than 1000 km from their natal region. These results have implications for the management of sea trout in inshore waters around the English Channel and southern North Sea.

evolutionary biology↗

The structure of an Amyloid Precursor Protein/talin complex indicates a mechanical basis of Alzheimer's Disease.

Misprocessing of Amyloid Precursor Protein (APP) is one of the major causes of Alzheimers disease. APP is a transmembrane protein comprising a large extracellular region, a single transmembrane helix and a short cytoplasmic tail containing an NPxY motif (normally referred to as the YENPTY motif). Talins are synaptic scaffold proteins that connect the cytoskeletal machinery to the plasma membrane via binding to one of two highly conserved NPxY motifs in the cytoplasmic tail of integrin transmembrane receptors. Here we report the crystal structure of an APP/talin1 complex identifying a new way to couple the cytoskeletal machinery to synaptic sites via APP. Proximity Ligation Assay (PLA) confirmed the close proximity of talin1 and APP in primary neurons, and we show that talin1 depletion has a dramatic effect on APP processing in cells. Structural modelling indicates that APP has the capacity to form an extracellular meshwork that mechanically couples the cytoskeletal meshworks of both the pre-, and post-synaptic compartments. In this context, we propose APP processing as a mechanical signalling pathway with similarities to Notch signalling, whereby the cleavage sites in APP represent mechanical sensors, with varying accessibility to cleavage by secretases. During synaptogenesis in healthy neurons, the APP/talin linkage would provide an exquisite mechanical coupling between synapses, with tightly controlled APP processing providing instructions to maintain this synchrony. Furthermore, APP directly coupling to the binary switches in talin indicates a role for APP in mechanical memory storage as postulated by the MeshCODE theory. The implication that APP is a regulator of mechanical signalling leads to a new hypothesis for Alzheimers disease, where mis-regulation of APP dynamics results in loss of mechanical integrity of the synapse, corruption and loss of mechanical binary data, and excessive generation of the toxic plaque-forming A{beta}42 peptide. Much needs to be done to experimentally validate this idea, but we present here a novel theory of Alzheimers Disease with a role for APP in the mechanically coded binary information storage in the synapse, which identifies a potential novel therapeutic strategy for treating Alzheimers Disease. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=131 SRC="FIGDIR/small/583202v4_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@ba0768org.highwire.dtl.DTLVardef@13c4672org.highwire.dtl.DTLVardef@352178org.highwire.dtl.DTLVardef@288bf6_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO Graphical Abstract Legend: Amyloid Precursor Protein (APP) forms an extracellular meshwork that provides a coupling between the mechanical signalling machinery of the pre- and post-synaptic neurons.A) APP binds to talin indicating that APP will experience mechanical forces which leads us to propose that APP processing is a Notch-like signalling pathway that maintains mechanical homeostasis at the synapse. B) The crystal structure of APP bound to talin F2F3. C) APP is part of the adhesion complex that attaches talin to the membrane. D) The loss of adhesion integrity in the synapse, or other factors that lead to misprocessing of APP will perturb this coupling and contribute to Alzheimers Disease. See also Movie 1. C_FIG

neuroscience↗

Aperiodic and Hurst EEG exponents across early human brain development: a systematic review

In electroencephalographic (EEG) data, power-frequency slope exponents (1/f{beta}) can provide non-invasive markers of in vivo neural activity excitation-inhibition (E:I) balance. E:I balance may be altered in neurodevelopmental conditions; hence, understanding how 1/f{beta} evolves across infancy/childhood has implications for developing early assessments/interventions. This systematic review (PROSPERO-ID: CRD42023363294) explored the early maturation (0-26yrs) of resting-state EEG 1/f measures (aperiodic [AE], power law [PLE] and Hurst [HE] exponents), including studies containing [≥]1 1/f measures and [≥]10 typically developing participants. Five databases (including Embase and Scopus) were searched during March 2023. Forty-two studies were identified (Nparticipants=3478). Risk of bias was assessed using the Quality Assessment with Diverse Studies tool. Narrative synthesis of HE data suggests non-stationary EEG activity occurs throughout development. Age-related trends were complex, with rapid decreases in AEs during infancy and heterogenous changes thereafter. Regionally, AE maxima shifted developmentally, potentially reflecting spatial trends in maturing brain connectivity. This work highlights the importance of further characterising the development of 1/f measures to better understand how E:I balance shapes brain and cognitive development.

neuroscience↗

Synaptic Activity Causes Minute-scale Changes in BAF Complex Composition and Function

Genes encoding subunits of the SWI/SNF or BAF ATP-dependent chromatin remodeling complex are among the most enriched for deleterious de novo mutations in intellectual disabilities and autism spectrum disorder, but the causative molecular pathways are not fully known1,2. Synaptic activity in neurons is critical for learning and memory and proper neural development3. Neural activity prompts calcium influx and transcription within minutes, facilitated in the nucleus by various transcription factors (TFs) and chromatin modifiers4. While BAF is required for activity-dependent developmental processes such as dendritic outgrowth5-7, the immediate molecular consequences of neural activity on BAF complexes and their functions are unknown. Here we mapped minute-scale biochemical consequences of neural activity, modeled by membrane depolarization of embryonic mouse primary cortical neurons, on BAF complexes. We used acute chemical perturbations of BAF ATPase activity and kinase signaling to define the activity-dependent effects on BAF complexes and activity-dependent BAF functions. Our studies found that BAF complexes change in subunit composition and are selectively phosphorylated within 10 minutes of depolarization. Increased levels of the core PBAF subunit Baf200/Arid2, uniquely containing an RFX-like DNA-binding domain, are concurrent with ATPase-dependent opening of chromatin at RFX/X-box motifs. Changes in BAF composition and phosphorylation lead to the regulation of chromatin accessibility for critical neurogenesis TFs. These biochemical effects are a convergent phenomenon downstream of multiple growth factor signaling pathways in mouse neurons and fibroblasts suggesting that BAF integrates signaling information from the membrane. In support of such a membrane-to-nucleus signaling cascade, we also identified a BAF-interacting kinase, Dclk2, whose inhibition attenuates BAF phosphorylation selectively. Our findings support a direct role of BAF complexes in responding to synaptic activity to regulate TF binding and transcription.

molecular biology↗

Blood prognostic biomarker signatures for hemorrhagic cerebral cavernous malformations (CCMs)

BackgroundCerebral cavernous malformations (CCMs) is a neurological disorder that causes enlarged intracranial capillaries in the brain, leading to an increased risk of hemorrhagic strokes, which is a leading cause of death and disability worldwide. ObjectivesThe current treatment options for CCMs are limited, highlighting the need for prognostic biomarkers to predict the risk of hemorrhagic events to better inform treatment decisions and identify future pharmacological targets. Eligibility CriteriaThe study is centered on a comparative proteomic analysis between hemorrhagic CCMs (HCs) and healthy controls, while excluding patients with non-hemorrhagic CCMs (NHCs) from the analysis due to the experimental design. Sources of EvidenceRecent research has identified several serum biomarkers and blood circulating biomarkers in a selected cohort of homogeneous CCM patients and animal models. MethodProteomic profiles from both human and mouse CCM models were examined, and pathway enrichment analyses were performed using three approaches (GO, KEGG, and DOSE). To account for multiple comparisons, t-tests were employed to evaluate differences. A p-value below 0.05 was deemed statistically significant. ResultsThe authors have developed the first panel of candidate biomarker signatures, featuring both etiological and prognostic markers in two distinct pathways. This panel of biomarker signatures demonstrates a robust correlation with the likelihood of hemorrhagic CCMs. ConclusionsThis groundbreaking biomarker panel paves the way for further investigation of potential blood biomarkers to determine the risk of hemorrhagic CCMs.

genomics↗

Integration of single-cell multiomic measurements across disease states with genetics identifies mechanisms of beta cell dysfunction in type 2 diabetes

Altered function and gene regulation of pancreatic islet beta cells is a hallmark of type 2 diabetes (T2D), but a comprehensive understanding of mechanisms driving T2D is still missing. Here we integrate information from measurements of chromatin activity, gene expression and function in single beta cells with genetic association data to identify disease-causal gene regulatory changes in T2D. Using machine learning on chromatin accessibility data from 34 non-diabetic, pre-T2D and T2D donors, we robustly identify two transcriptionally and functionally distinct beta cell subtypes that undergo an abundance shift in T2D. Subtype-defining active chromatin is enriched for T2D risk variants, suggesting a causal contribution of subtype identity to T2D. Both subtypes exhibit activation of a stress-response transcriptional program and functional impairment in T2D, which is likely induced by the T2D-associated metabolic environment. Our findings demonstrate the power of multimodal single-cell measurements combined with machine learning for identifying mechanisms of complex diseases.

systems biology↗

CCM signaling complex (CSC) coupling both classic and non-classic progesterone receptor signaling

Excessive progesterone (PRG) may increase breast cancer risk under hormone therapy during postmenopause or hormonal contraception. As a sex steroid hormone, PRG exerts its cellular responses through signaling cascades involving classic (genomic), non-classic (non-genomic), or both combined responses by binding to either classic nuclear PRG receptors or non-classic membrane PRG receptors. Currently, the intricate balance and switch mechanisms between these two signaling cascades remain elusive. Three genes, KRIT1 (CCM1), MGC4607 (CCM2), and PDCD10 (CCM3), have been demonstrated to form a CCM signaling complex (CSC). In this report, we discover that the CSC plays an essential role in coupling both classic and non-classic PRG signaling pathways by mediating crosstalk between them. The coupled signaling pathways were detailed through high throughput omics. One Sentence SummaryWe discover a novel signaling network among the CCM signaling complex (CSC), classic and non-classic progesterone receptors, and their ligands-progesterone/mifepristone, is dynamically modulated and fine-tuned with a series of feedback regulations; perturbation of this intricate balance, such as hormone therapy in the postmenopause or hormonal contraception regimen, or perturbed CSC signaling could result in increased risks in breast cancer or compromising tumor therapy.

neuroscience↗

Searching through functional space reveals distributed visual, auditory, and semantic coding in the human brain

The extent to which brain functions are localized or distributed is a foundational question in neuroscience. In the human brain, common fMRI methods such as cluster correction, atlas parcellation, and anatomical searchlight are biased by design toward finding localized representations. Here we introduce the functional searchlight approach as an alternative to anatomical searchlight analysis, the most commonly used exploratory multivariate fMRI technique. Functional searchlight removes any anatomical bias by grouping voxels based only on functional similarity and ignoring anatomical proximity. We report evidence that visual and auditory features from deep neural networks and semantic features from a natural language processing model are more widely distributed across the brain than previously acknowledged. This approach provides a new way to evaluate and constrain computational models with brain activity and pushes our understanding of human brain function further along the spectrum from strict modularity toward distributed representation.

neuroscience↗

Ins2 gene bursting activity defines a mature beta-cell state

Transcriptional and functional cellular specialization has been described for insulin-secreting {beta}-cells of the endocrine pancreas. However, it is not clear whether {beta}-cell heterogeneity is stable or reflects dynamic cellular states. We investigated the temporal kinetics of endogenous insulin gene activity using live cell imaging, with complementary experiments employing FACS and single cell RNA sequencing, in {beta}-cells from Ins2GFP knock-in mice. In vivo staining and FACS analysis of islets from Ins2GFP mice confirmed that at a given moment, ~25% of {beta}-cells exhibited significantly higher activity at the conserved insulin gene Ins2. Live cell imaging captured Ins2 gene activity dynamics in single {beta}-cells over days. Autocorrelation analysis revealed a subset of cells with oscillating behavior, with mean oscillation periods of 17 hours. Increased glucose concentrations stimulated more cells to oscillate and resulted in higher average Ins2 gene activity per cell. Single cell RNA sequencing showed that Ins2(GFP)HIGH {beta}-cells were enriched for markers of {beta}-cell maturity. Ins2(GFP)HIGH {beta}-cells were also significantly less viable at all glucose concentrations and in the context of ER stress. Collectively, our results demonstrate that the heterogeneity of insulin production, observed in mouse and human {beta}-cells, can be accounted for by dynamic states of insulin gene activity. BlurbPreviously reported pancreatic {beta}-cell heterogeneity reflects {beta}-cell state transitions.

cell biology↗

Systems-wide analysis unravels the new roles of CCM signal complex (CSC)

Cerebral cavernous malformations (CCMs) are characterized by abnormally dilated intracranial capillaries that result in increased susceptibility to stroke. Three genes have been identified as causes of CCMs; KRIT1 (CCM1), MGC4607 (CCM2) and PDCD10 (CCM3); one of them is disrupted in most CCM cases. It was demonstrated that both CCM1 and CCM3 bind to CCM2 to form a CCM signaling complex (CSC) to modulate angiogenesis. In this report, we deployed both RNA-seq and proteomic analysis of perturbed CSC after depletion of one of three CCM genes to generate interactomes for system-wide studies. Our results demonstrated a unique portrait detailing alterations in angiogenesis and vascular integrity. Interestingly, only in-direct overlapped alterations between RNA and protein levels were detected, supporting the existence of multiple layers of regulation in CSC cascades. Notably, this is the first report identifying that both {beta}4 integrin and CAV1 signaling are downstream of CSC, conveying the angiogenic signaling. Our results provide a global view of signal transduction modulated by the CSC, identifies novel regulatory signaling networks and key cellular factors associated with CSC.

systems biology↗

Facilitating open-science with realistic fMRI simulation: validation and application

BackgroundWith advances in methods for collecting and analyzing fMRI data, there is a concurrent need to understand how to reliably evaluate and optimally use these methods. Simulations of fMRI data can aid in both the evaluation of complex designs and the analysis of data. New MethodWe present fmrisim, a new Python package for standardized, realistic simulation of fMRI data. This package is part of BrainIAK: a recently released open-source Python toolbox for advanced neuroimaging analyses. We describe how to use fmrisim to extract noise properties from real fMRI data and then create a synthetic dataset with matched noise properties and a user-specified signal. ResultsWe validate the noise generated by fmrisim to show that it can approximate the noise properties of real data. We further show how fmrisim can help researchers find the optimal design in terms of power. Comparison with other methodsfmrisim ports the functionality of other packages to the Python platform while extending what is available in order to make it seamless to simulate realistic fMRI data. ConclusionsThe fmrisim package holds promise for improving the design of fMRI experiments, which may facilitate both the pre-registration of such experiments as well as the analysis of fMRI data. HighlightsO_LIfmrisim can simulate fMRI data matched to the noise properties of real fMRI. C_LIO_LIThis can help researchers investigate the power of their fMRI designs. C_LIO_LIThis also facilitates open science by making it easy to pre-register analysis pipelines. C_LI

neuroscience↗

Computational assessment of blood flow heterogeneity in dialysis patients’ cardiac ventricles

Dialysis prolongs life but augments cardiovascular mortality. Imaging data suggests that dialysis increases myocardial blood flow (BF) heterogeneity, but its causes remain poorly understood. A biophysical model of human coronary vasculature was used to explain the imaging observations, and highlight causes of coronary BF heterogeneity.\n\nPost-dialysis CT images from patients under control, pharmacological stress (adenosine), therapy (cooled dialysate), and adenosine and cooled dialysate conditions were obtained. The data presented disparate phenotypes. To dissect vascular mechanisms, a 3D human coronary vasculature model was implemented. Simulations were performed to investigate the effects of altered aortic pressure and blood vessel diameters on myocardial BF heterogeneity which was quantified using relative dispersion, fractal dimension, and transmural BF distribution.\n\nImaging showed that stress and therapy potentially increased mean and total BF, while reducing heterogeneity. BF histograms of one patient showed multi-modality. Using the model, it was found that total coronary BF increased as coronary perfusion pressure (CPP) was increased. BF heterogeneity was differentially affected by large or small vessel blocking. BF heterogeneity was found to be inversely related to small blood vessel diameters. Simulation of large artery stenosis indicates that BF became heterogeneous (increase relative dispersion) and gave multi-modal histograms. The total transmural BF as well as transmural BF heterogeneity reduced due to large artery stenosis, generating large patches of very low O_SCPCAPBFC_SCPCAP regions downstream. Blocking of arteries at various orders showed that blocking larger arteries results in multi-modal BF histograms and large patches of low BF, whereas smaller artery blocking results in augmented relative dispersion and fractal dimension. Transmural heterogeneity was also affected. Finally, the effects of augmented aortic pressure in the presence of blood vessel blocking shows differential effects on BF heterogeneity as well as transmural BF.\n\nImproved aortic blood pressure may lead to improved BF. Stress and therapy may be effective if they dilate small vessels. A potential cause for the observed complex BF distributions (multi-modal BF histograms) may indicate existing large vessel stenosis.\n\nThe intuitive BF heterogeneity methods used can be readily used in clinical studies. Further development of the model and methods will permit personalised assessment of patient BF status.

biophysics↗