Biology subjects

Hurley, M. E.

Publications and source records attributed to Hurley, M. E..

4 recordsLinked to original sources

bioRxiv2026

Structural and functional heterogeneity in cardiac RyR signalling nanodomains revealed with quantitative single molecule mapping toolkit

The nanoscale organisation of ryanodine receptor type 2 (RyR2) channels and junctophilin-2 (JPH2) shapes cardiac Ca{superscript 2} release, but how this relationship is remodelled in right ventricular failure remains unclear. We developed an integrated analysis pipeline building on multiplexed DNA-PAINT data to quantify RyR2 and JPH2 abundance, stoichiometry of co-clustering, and spatial organisation within individual subsarcolemmal Ca{superscript 2}-release nanodomains. Applied to cardiomyocytes from control rats with pulmonary hypertension-induced right ventricular failure, the approach revealed reduced co-localisation between RyR2 and JPH2 within peripheral junctions and greater variability in their co-clustering stoichiometry across the cell. A sub-variogram analysis further showed divergent remodelling of JPH2 expression patterns across subcellular length scales, indicating that disease alters both local molecular composition and cell-wide spatial heterogeneity. Experimentally derived RyR2/JPH2 maps were then used to model as two-dimensional templates for stochastic reaction-diffusion of Ca{superscript 2} release. Simulations of spontaneous Ca{superscript 2} waves from failing cells showed up to 25% wave propagation. Maps from failing cells supported faster transverse and longitudinal Ca{superscript 2} dependent release, consistent with the emergence, that support the likelihood of heterogeneous modulation and coupling of RyR resulting from the RyR redistribution and heterogeneous JPH2 expression in the failing cell. Together, these findings identify spatially heterogeneous RyR2-JPH2 remodelling as a potential substrate for dysregulated Ca{superscript 2} signalling in right ventricular failure and establish a transferable toolkit for linking molecular nanostructure to cellular function.

cell biology↗

bioRxiv2023

Correlative super-resolution analysis of cardiac calcium sparks and their molecular origins in health and disease

Rapid release of calcium from internal stores via ryanodine receptors (RyRs) is one of the fastest types of cytoplasmic second messenger signalling in excitable cells. In the heart, rapid summation of the elementary events of calcium release, calcium sparks, determine the contraction of the myocardium. Recent advances in super-resolution microscopy methods have revealed complex clustering patterns of RyRs at single-channel resolution. Here, we have experimentally correlated sub-sarcolemmal spontaneous calcium sparks in rat right ventricular myocytes with the underlying nanoscale sub-sarcolemmal RyR patterns resolved with super-resolution DNA-PAINT microscopy. Local functional groupings and clustering patterns of RyR were sampled by the location and the two-dimensional area of each calcium spark to reveal a steep dependence of the integral of a calcium spark on the sum of the local RyRs. Visualisation of recurring spark sites showed evidence of repeated and triggered saltatory activation of multiple local RyR clusters. In similar myocytes taken from rats with induced right ventricular failure, RyR clusters themselves showed a dissipated morphology and fragmented (smaller) clusters. The failing myocytes featured greater heterogeneity in both the spark properties and the relationship between the integral of the calcium spark and the local ensemble of RyRs. Whilst fragmented (smaller) RyR clusters were rarely observed to directly underlying the larger sparks or the recurring spark sites, local interrogation of the channel-to-channel distances confirmed a clear link between the positions of each calcium spark and the tight non-random clustering of the local RyRs in both healthy and failing ventricles.

biophysics↗

bioRxiv2021

3D visualisation of the cardiac ryanodine receptor clusters and the molecular-scale fraying of dyads

Clusters of ryanodine receptor calcium channels (RyRs) form the primary molecular machinery in cardiomyocytes. Various adaptations of super-resolution microscopy have revealed intricate details of the structure, molecular composition and locations of these couplons. However, most optical super-resolution techniques lack the capacity for three-dimensional (3D) visualisation. Enhanced Expansion Microscopy (EExM) offers resolution (in-plane and axially) sufficient to spatially resolve individual proteins within peripheral couplons and within dyads located in the interior. We have combined immunocytochemistry and immunohistochemistry variations of EExM with 3D visualisation to examine the complex topologies, geometries and molecular sub-domains within RyR clusters. We observed that peripheral couplons exhibit variable co-clustering ratios and patterns between RyR and the structural protein, junctophilin-2 (JPH2). Dyads possessed sub-domains of JPH2 which occupied the central regions of the RyR cluster, whilst the poles were typically devoid of JPH2 and broader, and likely specialise in turnover and remodelling of the cluster. In right ventricular myocytes from rats with monocrotaline-induced right ventricular failure, we observed hallmarks of RyR cluster fragmentation accompanied by similar fragmentations of the JPH2 sub-domains. We hypothesise that the frayed morphology of RyRs in close proximity to fragmented JPH2 structural sub-domains may form the primordial foci of RyR mobilisation and dyad remodelling.

biophysics↗

bioRxiv2020

A super-resolution protocol to correlate structural underpinnings of fast second-messenger signalling in primary cell types

Nanometre-scale cellular information obtained through super-resolution microscopies are often unaccompanied by functional information, particularly transient and diffusible signals through which life is orchestrated in the nano-micrometre spatial scale. We describe a correlative imaging protocol which allows the ubiquitous intracellular second messenger, calcium (Ca2+), to be directly visualised against nanoscale patterns of the ryanodine receptor (RyR) Ca2+ channels which give rise to these Ca2+ signals in wildtype primary cells. This was achieved by combining total internal reflection fluorescence (TIRF) imaging of the elementary Ca2+ signals, with the subsequent DNA-PAINT imaging of the RyRs. We report a straightforward image analysis protocol of feature extraction and image alignment between correlative datasets and demonstrate how such data can be used to visually identify the ensembles of Ca2+ channels that are locally activated during the genesis of cytoplasmic Ca2+ signals.

biophysics↗