Biology subjects

Keavney, B. D.

Publications and source records attributed to Keavney, B. D..

5 recordsLinked to original sources

bioRxiv2026

GPC6 Lipid Shielding Sustains WNT5A Gradients to Prevent a RASopathy-like Developmental State

Morphogen gradients require ligands to disperse across tissues from their sites of production, yet receptor engagement can consume ligand before it reaches distant cells. This poses a particular challenge for lipid-modified WNTs, whose hydrophobic palmitoleate favours ligand retention near their source and premature receptor engagement. Here we identify a palmitoleate-binding pocket in mammalian glypican-6 (GPC6), the gene mutated in the skeletal dysplasia omodysplasia, and show that shielding of the WNT5A lipid by GPC6 is required for gradient formation. Using a separation-of-function knock-in mouse allele, we demonstrate that targeted disruption of GPC6-mediated lipid shielding collapses WNT5A gradients during skeletal development by promoting premature source-proximal signalling that depletes ligand available for distal signalling. This source-proximal WNT hyperactivation engages a previously unrecognised WNT-driven RAC-PAK-MEK-ERK cascade, generating a RASopathy-like developmental state that contributes to skeletal dysplasia. Thus, GPC6 functions as a spatial gatekeeper of WNT5A utilisation, controlling the allocation of a finite ligand pool. More broadly, these findings reveal that pathway hyperactivation can arise from spatial misallocation of an endogenous signalling ligand rather than from conventional gain- or loss-of-function mutations in downstream signalling components.

developmental biology↗

bioRxiv2025

Endurance exercise remodels pulmonary vein sleeve myocytes and promotes a proarrhythmic atrial substrate

BACKGROUNDAtrial fibrillation (AF) susceptibility is heightened in endurance athletes but the underlying mechanisms are incompletely understood. Because pulmonary vein (PV) myocyte triggers are critical determinants of AF, we investigated PV electrophysiological remodelling in animal models of the athletes heart. METHODSThe following experiments were performed in canines and mice after 16 or 6 weeks, respectively, of daily exercise training (ExT), and compared to sedentary (Sed) controls: ECG recording, echocardiography, pharmacological autonomic block, extrastimulus pacing, multielectrode array mapping, monophasic and intracellular action potential (AP) recording with custom-designed pattern recognition analysis, histology, RNAseq and spatial in situ transcriptomics. RESULTSAF propensity was significantly increased in ExT animals. Mapping studies identified heightened rotational activity in the PV-left atrial (LA) junction of ExT vs. Sed canines in vivo, and enhanced automaticity, triggered activity and AP duration variability ex vivo in ExT canines and mice. Intracellular recordings in mouse PV cardiomyocytes determined at least six AP subtypes with increased frequency of pacemaker-like APs in ExT PV, concomitant with increased expression of pacemaking HCN4, Cav1.3 and Cav3.1 channels. PV spontaneous excitability was also significantly enhanced. Subcellular resolution spatial transcriptomics in mouse PV-LA identified diffuse ion channel remodelling and activation of established AF-promoting pro-inflammatory and pro-fibrotic cytokines and chemokines in ExT PV cardiomyocytes. Conduction slowing in the ExT PV-LA junction was attributable to: gap junction remodelling, reduced Na+ channel expression and increased extracellular matrix deposition with enhanced myofibroblast number and proximity to PV cardiomyocytes. CONCLUSIONSEndurance exercise elicits proarrhythmic electro-anatomical remodelling of the PV-LA junction with enhanced pacemaking ion channel expression and immune-inflammatory pathway activation in PV myocytes as prominent contributors. CLINICAL PERSPECTIVEO_ST_ABSWhat is new?C_ST_ABSO_LIThis work is the first demonstration that endurance training results in proarrhythmic electrophysiological remodelling of PV sleeve myocytes and extracellular matrix deposition in the PV-LA junction. C_LIO_LIWe register electrical and molecular heterogeneity of the PV-LA junction at single cell and subcellular resolution, and for the first time identify the molecular events that underlie increased proarrhythmic activity of the trained PV. These include enhanced pacemaking ion channel expression (e.g., HCN4, Cav1.3, and Cav3.1), pro-inflammatory cytokine activation (e.g., TNF, IL-6), increased myofibroblasts and extracellular matrix deposition. C_LI What are the clinical implications?O_LIWe identify the molecular determinants of PV proarrhythmic activity in the trained heart and present new therapeutic targets for AF prevention in athletes. C_LIO_LIOur findings provide mechanistic rationale for the efficacy of pulmonary vein isolation for AF in athletes. C_LI

physiology↗

bioRxiv2024

A Machine Learning Classifier to Identify and Prioritise Genes Associated with Cardiac Development

Congenital heart disease (CHD) is a major cause of infant mortality and presents life-long challenges to individuals living with these conditions. Genetic causes are known for only a minority of types of CHD. Discovering further genetic causes is limited by challenges in prioritising candidate CHD genes. We examined a wide range of features of mouse genes, including sequence characteristics, protein localisation and interaction data, developmental expression data and gene ontology annotations. Many features differ between cardiac development and non-cardiac genes, suggesting that these two gene types can be distinguished by their attributes. Therefore, we developed a supervised machine learning (ML) method to identify Mus musculus genes with a high probability of being involved in cardiac development. These genes, when mutated, are candidates for causing human CHD. Our classifier showed a cross-validation accuracy of 81% in detecting cardiac and non-cardiac genes. From our classifier we generated predictions of the cardiac development association status for all protein-coding genes in the mouse genome. We also cross-referenced our predictions with datasets of known human CHD genes, determining which are orthologues of predicted mouse cardiac genes. Our predicted cardiac genes have a high overlap with human CHD genes. Thus, our predictions could inform the prioritisation of genes when evaluating CHD patient sequence data for genetic diagnosis. Knowledge of cardiac developmental genes may speed up reaching a genetic diagnosis for patients born with CHD. Author SummaryCongenital heart disease arises during pregnancy when the heart has formed incorrectly. These malformations affect [~]1% of newborns. Yet, despite their frequency, the underlying causes are still not known in many cases. It is clear that genetic factors contribute to these defects, and increasingly DNA sequencing is used to attempt to determine if an individual has a genetic change causative of their condition. However, analysis of patient sequence data often reveals changes that are difficult to interpret due to a lack of knowledge of the function of the gene harbouring a sequence change. We aimed to facilitate the process of sequence evaluation by predicting which genes of unknown function are likely involved in heart formation. Our predictions agree with novel experimental evidence about genes needed for heart development. We found that when mutated, a high proportion of the predicted cardiac genes do indeed cause heart defects. This result suggests that our predictions may be informative for expanding our understanding of the genetic basis of congenital heart disease.

genomics↗

bioRxiv2019

Heritability and family-based GWAS analyses of the N-acyl ethanolamine and ceramide lipidome reveal genetic influence over circulating lipids

Signalling lipids of the N-acyl ethanolamine (NAE) and ceramide (CER) classes are emerging as novel cardiovascular disease biomarkers. We sought to establish the heritability of plasma NAEs (including the endocannabinoid anandamide) and CERs, and identify common DNA variants influencing the circulating concentrations of the heritable lipid species. Nine NAE and sixteen CER species were analysed in plasma samples from 999 members of 196 British Caucasian families, using targeted mass spectrometry (UPLC-MS/MS). Heritability was estimated and GWAS analyses were undertaken; all target lipids were significantly heritable (h2 = 36%-62%). A missense variant (rs324420) in the gene encoding the enzyme fatty acid amide hydrolase (FAAH), which degrades NAEs, associated at GWAS significance (P<2.15x10-8) with four NAEs (DHEA, PEA, LEA, VEA). The A allele of this SNP was associated with a 0.23 SD per-allele increase in plasma NAE species. Additionally, we found association between rs680379 in the SPTLC3 gene, which encodes a subunit of the rate limiting enzyme in CER biosynthesis, and a range of CER species (e.g. CER[N(24)S(19)]; P =4.82x10-27). We also observed three novel associations (CD83, SGPP1, FBXO28-DEGS1) influencing plasma CER traits, two of which (SGPP1 and DEGS1) implicate CER species in haematological phenotypes. NAE and CER are substantially heritable bioactive lipids, influenced by SNPs in key metabolic enzymes.

genetics↗

bioRxiv2018

Deleterious genetic variants in NOTCH1 are a major contributor to the incidence of non-syndromic Tetralogy of Fallot

AimsFamilial recurrence studies provide strong evidence for a genetic component to the predisposition to sporadic, non-syndromic Tetralogy of Fallot (TOF), the most common cyanotic congenital heart disease (CHD) phenotype. Rare genetic variants have been identified as important contributors to the risk of CHD, but relatively small numbers of TOF cases have been studied to date. Here, we use whole exome sequencing to assess the prevalence of rare, potentially deleterious variants in candidate genes previously associated with both syndromic and non-syndromic TOF, in the largest cohort of non-syndromic TOF patients reported to date.\n\nMethods & Results829 non-syndromic TOF patients underwent whole exome sequencing. A systematic review of the literature was conducted which revealed 77 genes in which mutations had been reported in patients with TOF. The presence of rare, deleterious variants in the 77 candidate genes was determined, defined by a minor allele frequency of [≤] 0.001 and scaled combined annotation-dependent depletion (CADD) score of [≥] 20. We found a clustering of heterozygous rare, deleterious variants in NOTCH1 (P=1.89E-15), DOCK6 (P=2.93E-07), MYOM2 (P= 7.35E-05), TTC37 (P=0.016), MESP1 (P=0.024) and TBX1 (P=0.039), after correcting for multiple testing. NOTCH1 was most frequently found to harbour deleterious variants. Changes were observed in 49 patients (6%; 95% confidence interval [CI]: 4.5% - 7.8%) and included six truncating/frameshift variants and forty missense variants. Sanger sequencing of the unaffected parents of thirteen cases identified five de novo variants. Variants were not confined to a single functional domain of the NOTCH1 protein but significant clustering of variants was evident in the EGF-like repeats (P=0.018). Three NOTCH1 missense variants (p.G200R, p.C607Y and de novo p.N1875S) were subjected to functional evaluation and showed a reduction in Jagged1 ligand-induced NOTCH signalling. p.C607Y, which exhibited the most significant reduction in signalling, also perturbed S1 cleavage of the NOTCH1 receptor in the Golgi.\n\nConclusionThe NOTCH1 locus is a frequent site of genetic variants predisposing to non-syndromic TOF with 6% of patients exhibiting rare, deleterious variants. Our data supports the polygenic origin of TOF and suggests larger studies may identify additional loci.

genetics↗