Biology subjects

Wicki-Stordeur, L. E.

Publications and source records attributed to Wicki-Stordeur, L. E..

5 recordsLinked to original sources

bioRxiv2026

Ankyrin-B regulates cardiomyocyte sarcomere organization and its protein-protein interactions are significantly altered by p.S646F expression

Ankyrin-B (ANKB) is a large (220 kDa) multi-domain membrane-localized cytoplasmic protein that acts as a scaffold coordinating cytoskeletal, ion channel, and transporter proteins critical for proper cardiomyocyte structure and function. There is a prevalence of structural cardiac abnormalities within the cohort of the novel ANKB p.S646F variant that we previously identified in two multigenerational Gitxsan First Nation families, suggesting a role for ANKB in cardiac structure. To investigate the impact of ANKB on cardiomyocyte structural organization, we imaged sarcomere structure in primary cardiomyocytes from cardiac-specific ANKB heterozygous (expressing lower levels of ANKB) and full knock-out mice using confocal microscopy. We observed marked disruption of sarcomere structure in primary cardiac cultures associated with lower ANKB expression, suggesting ANKB is required for proper development of sarcomeres. To shed light on the underlying mechanisms, we next employed an unbiased proteomics approach to identify novel ANKB protein-protein interactions. This analysis uncovered a novel ANKB interaction with -actinin-1, an actin-binding protein that stabilizes focal adhesions essential for development of cardiomyocyte structure. Western blot comparison of -actinin-1 co-precipitation with wildtype ANKB and ANKB p.S646F, revealed increased -actinin-1 enrichment with ANKB p.S646F. Bioinformatics analysis of the ANKB interactome revealed enrichment of cytoskeletal organization, sarcomere structure, and chaperone proteins, and marked changes with ANKB p.S646F. Together findings point to a novel role for ANKB in the regulation of cardiomyocyte structural development and support additional investigation into a link between p.S646F and cardiac structural abnormalities.

cell biology↗

bioRxiv2025

ATP increases murine neuroblastoma cell size through a PANX1- and macropinocytosis-dependent mechanism

Macropinocytosis is an endocytic process that allows cells to respond to changes in their environment by internalizing nutrients and cell surface proteins, as well as modulating cell size. Here, we identify that adenosine triphosphate (ATP) triggers macropinocytosis in murine Neuro2a neuroblastoma cells, driving an increase in cell size, and internalizing the ATP release channel pannexin 1 (PANX1) to macropinosomes. Amiloride treatment and mutation of an extracellular tryptophan (W74) in PANX1 abolished ATP-evoked cell area enlargement, suggesting that PANX1 may itself regulate this form of macropinocytosis. Transient expression of the GTP-hydrolysis resistant ADP-ribosylation factor 6 GTPase (ARF6 Q67L) led to increased cell size, PANX1 internalization and localization to endosomal compartments, consistent with macropinocytosis. Inhibiting macropinocytosis-associated GTPases, phosphoinositide-3 kinase (PI3K), and disrupting actin polymerization abolished ATP-induced PANX1 internalization supporting a macropinocytic mechanism. Further, these inhibitors disrupted co-distribution of intracellular PANX1 with macropinosomal cargo. Several lipid-PANX1 interactions were identified with relevance to macropinocytic mechanisms. The role of PANX1 in ATP-mediated macropinocytosis could be particularly important for disease states implicating PANX1, such as cancer, where ATP can act as a purinergic regulator of cell growth/metastasis and as a supplementary energy source following internalization.

cell biology↗

bioRxiv2025

Transient, early, female-specific increase in cortical glial fibrillary acidic protein distribution in the Syrian hamster model of mild peripheral COVID-19

BackgroundMild-moderate respiratory COVID-19 is commonly associated with a range of neurological symptoms. The mechanisms linking this peripheral disease to cognitive symptoms are thought to include heightened circulating cytokines and other inflammatory mediators resulting in a leaky blood-brain barrier and increased neuroinflammation (i.e., inflammation taking place in the brain). This can lead to aberrant synaptic transmission and cognitive dysfunction. A key component of neuroinflammation is the reactivity of astrocytes, in a process termed astrogliosis, associated with altered morphology, proliferative capacity, gene expression, and function. Accumulating evidence suggests astrogliosis likely occurs in mild-moderate COVID-19; however, there has been limited investigation. In this study, we quantified changes to astrocytes in a Syrian hamster model of mild-moderate respiratory COVID-19. MethodsWe used an intranasal inoculation model to produce mild-moderate respiratory COVID-19 in 8-10-week-old male and female Syrian hamsters. We extracted brains at 1-, 3-, 5-, 7-, and 31-days post-inoculation and from uninfected controls, and immunolabelled brain sections with astrocyte- (GFAP and SOX9) and neuron-specific (NEUN) markers. We captured tiled confocal micrographs of entire brain sections and analyzed the resulting signals from five regions of interest: cortex, corpus callosum, hippocampus, third ventricle, and dorsal striatum. ResultsTo systematically quantify cell-type-specific labelling for astrogliosis markers, we first developed an unbiased pipeline. We found a transient increase in GFAP signal density in female hamster, specifically in the cortex at 3 days post-inoculation. There were no corresponding changes noted in astrocyte (SOX9), neuron (NEUN) or total cell (Hoechst) numbers. Moreover, there were no changes in male hamsters at any timepoint in any region of interest. ConclusionsOur findings provide the first spatiotemporal insight into astrogliosis in a hamster model of mild-moderate respiratory COVID-19. We identified a transient and sex-specific increase in GFAP signal density, indicative of astrogliosis. Our findings contribute to the literature surrounding sex differences in (neuro)immune responses and add to the growing body of COVID-19 literature, in which sex-specific outcomes are apparent in both human patient populations and rodent experimental models.

neuroscience↗

bioRxiv2024

Quantification of morphological, functional, and biochemical features of H9c2 rat cardiomyoblast retinoic acid differentiation

Cell culture models enable advancement in our understanding of heart development and heart disease. The H9c2 rat ventricular cardiomyoblast cell line can be differentiated, recapitulating certain components of cardiomyocyte development; however, morphological, functional, and biochemical changes are rarely investigated in parallel, thereby limiting fulsome understanding. We therefore characterized morphology, Ca2+ handling, and gene expression after five days (5 days-in-vitro, DIV5), and fourteen days (DIV14) of exposure to differentiation stimuli, consisting of retinoic acid and low serum. We observed several morphological changes with increasing time in differentiation, including increased mean length, area, eccentricity, and multinucleation, as well as an increase in actin clusters. Spontaneous Ca2+ transients in differentiated H9c2 cells had decreased frequency and synchronicity compared to those observed in primary cardiomyocytes. Additionally, key cardiomyocyte cytoskeletal proteins and ion channel transcript and protein expression levels changed significantly with differentiation, in alignment with changes normally observed in cardiomyocyte development. Our findings suggest H9c2 cells may be used as a high throughput screening model to investigate cardiomyocyte biology in certain developmental contexts with relevance to heart health and disease. HighlightsO_LIWe quantified morphology, Ca2+ handling, and gene expression changes in rat ventricular cardiomyoblast H9c2 cells across retinoic acid differentiation. C_LIO_LIWe compared multiple differentiation time points (mainly DIV0, DIV5, and DIV14) and observed time-dependent changes in all 3 aspects. We observed several morphological changes with increasing time in differentiation, including increased mean length, area, eccentricity, and multinucleation, as well as an increase in actin clusters. We observed the onset of spontaneous Ca2+ transients with differentiation, with further changes in subpopulations with increasing time in differentiation. Finally, we observed multiple changes in gene expression consistent with cardiomyocyte differentiation. C_LIO_LIWe summarize these parallel time-point dependent changes in morphology, Ca2+ handing, and gene expression to enable other researchers to optimize their study design. C_LI

cell biology↗

bioRxiv2019

Exploring the Pannexin 1 interactome: In silico cross-analyses with postsynaptic proteins and neuropsychiatric disorder susceptibility genes

Many neurological conditions exhibit synaptic impairments, suggesting mechanistic convergence. Additionally, the pannexin 1 (PANX1) channel and signalling scaffold is linked to several of these neurological conditions and is an emerging regulator of synaptic development and plasticity; however, its synaptic pathogenic contributions are relatively unexplored. To this end, we explored connections between synaptic neurodevelopmental disorder and neurodegenerative disease susceptibility genes discovered by genome-wide association studies (GWASs), and the neural PANX1 interactome (483 PANX1-interacting proteins identified from mouse Neuro2a cells). To identify shared susceptibility genes, we compared synaptic suggestive GWAS candidate genes amongst autism spectrum disorders, schizophrenia, Parkinsons disease, and Alzheimers disease. Next, to further probe PANX1 signalling pathways at the synapse, we used bioinformatics tools to identify PANX1 interactome signalling pathways and protein-protein interaction clusters. To shed light on synaptic disease mechanisms potentially linking PANX1 and these four neurological conditions, we performed additional cross-analyses between gene ontologies enriched for the PANX1 synaptic and disease-susceptibility gene sets. Finally, to explore the regional specificity of synaptic PANX1-neurological conditions connections, we identified brain region-specific elevations of synaptic PANX1 interactome and GWAS candidate gene set transcripts. Our results confirm considerable overlap in risk genes for autism spectrum disorders and schizophrenia and identify potential commonalities in genetic susceptibility for neurodevelopmental disorders and neurodegenerative diseases. Our findings also pinpointed novel putative PANX1 links to synaptic disease-associated pathways, such as regulation of vesicular trafficking and proteostasis, warranting further validation.

neuroscience↗