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Updated: Sep 20, 2025
Crystal Structure of the N-terminal Domain of Ryanodine Receptor from Plutella xylostella
Published on: November 30, 2018
Nanoscale organization of ryanodine receptor distribution and phosphorylation pattern determines the dynamics of
María Hernández Mesa1, Jonas van den Brink1, William E Louch2,3
1Department of Computational Physiology, Simula Research Laboratory, Oslo, Norway.
Insights
In heart failure, disrupted ryanodine receptor (RyR) clusters impair calcium sparks. Phosphorylation patterns within RyR clusters can compensate, but their location critically impacts spark dynamics.
Area of Science:
- Cardiology
- Biophysics
- Cellular Biology
Background:
- Super-resolution imaging reveals nanoscale organization of ryanodine receptors (RyRs) in cardiomyocytes.
- In heart failure (HF), RyR organization is disrupted, with RyRs dispersing into smaller, more numerous clusters.
- RyRs are hyperphosphorylated in HF, preferentially within cluster centers, complicating their functional impact.
Purpose of the Study:
- To computationally model the impact of RyR nanoscale organization and phosphorylation patterns on calcium (Ca2+) spark generation in failing cardiomyocytes.
- To investigate how RyR cluster geometry and phosphorylation distribution influence Ca2+ release dynamics.
Main Methods:
- Utilized computational modeling to simulate Ca2+ release from sarcoplasmic reticulum (SR) based on RyR cluster geometry and phosphorylation patterns.
- Quantified relationships between RyR organization, phosphorylation, and Ca2+ spark characteristics like fidelity, duration, and amplitude.
Main Results:
- RyR cluster disruption in HF leads to decreased Ca2+ spark fidelity and altered spark amplitude and duration.
- Phosphorylation of RyRs can partially restore normal Ca2+ spark dynamics.
- Model predicts that phosphorylation pattern is critical: central phosphorylation enhances spark fidelity more than uniform distribution.
Conclusions:
- Both nanoscale RyR reorganization and specific phosphorylation patterns are crucial determinants of Ca2+ dynamics in heart failure.
- Understanding these factors is key to addressing calcium handling abnormalities in failing hearts.
Abstract:
Super-resolution imaging techniques have provided a better understanding of the relationship between the nanoscale organization and function of ryanodine receptors (RyRs) in cardiomyocytes. Recent data have indicated that this relationship is disrupted in heart failure (HF), as RyRs are dispersed into smaller and more numerous clusters. However, RyRs are also hyperphosphorylated in this condition, and this is reported to occur preferentially within the cluster centre. Thus, the combined impact of RyR relocalization and sensitization on Ca2+ spark generation in failing cardiomyocytes is likely complex and these observations suggest that both the nanoscale organization of RyRs and the pattern of phosphorylated RyRs within clusters could be critical determinants of Ca2+ spark dynamics. To test this hypothesis, we used computational modeling to quantify the relationships between RyR cluster geometry, phosphorylation patterns, and sarcoplasmic reticulum (SR) Ca2+ release. We found that RyR cluster disruption results in a decrease in spark fidelity and longer sparks with a lower amplitude. Phosphorylation of some RyRs within the cluster can play a compensatory role, recovering healthy spark dynamics. Interestingly, our model predicts that such compensation is critically dependent on the phosphorylation pattern, as phosphorylation localized within the cluster center resulted in longer Ca2+ sparks and higher spark fidelity compared to a uniformly distributed phosphorylation pattern. Our results strongly suggest that both the phosphorylation pattern and nanoscale RyR reorganization are critical determinants of Ca2+ dynamics in HF.
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