Does anti-arrhythmic calmodulin cause concerted cardiac ryanodine receptor channel shut down?

Arrhythmias due to inappropriate Ca²⁺ signalling are inadequately managed due to lack of understanding of their physiological mechanisms, which makes it difficult to develop suitable pharmacological treatments. Dysfunctional Ca²⁺ release via the cardiac ryanodine receptor (RyR2) Ca²⁺-release channel is responsible for arrhythmia in genetic arrhythmia syndromes and cardiomyopathies as well as in heart failure. Under normal circumstances, RyR2 is regulated by the Ca²⁺ binding protein calmodulin (CaM), which acts to prevent channel opening, decreasing the frequency of Ca²⁺ ‘leaks’ during diastole which fuel arrhythmogenesis. RyR2 clustering is also thought to prevent uncontrolled Ca²⁺ release by promoting simultaneous opening and coordinated closure, keeping channels closed at low Ca²⁺ and open in activating Ca²⁺ with changes in cluster organisation proposed to play a role in cardiac disease.  Given that inappropriate opening of RyR2 is a common arrhythmia mechanism it seems logical that this channel has been targeted for therapeutic strategies. Many RyR2-directed drugs have found limited success because they work by reducing channel activity throughout the cardiac cycle – meaning that while diastolic Ca²⁺ release ceases to be a problem, systolic Ca²⁺ release is affected, weakening cardiac contraction. Recent work has pinpointed the potential use of a therapeutic CaM (TCaM), engineered to stabilise the channel’s closed conformation, with minimal effect on its ability to open. TCaM has been shown to decrease diastolic Ca²⁺ release in a mouse model of arrhythmia, though the exact mechanisms by which it does this aren’t completely resolved.

This project proposes to investigate whether TCaM exerts its effect by altering RyR2 channel behaviour at the level of the single channel or rather by promoting dynamic changes in channel clustering/cooperation (as it does for other cardiac channels). This will be uncovered by investigating the effects of TCaM on wild type or arrhythmia-linked mutant RyR2 at three organisational levels. Firstly, by using single channel recording to assess TCaM’s influence on individual RyR2 gating in a minimal environment. Then, by monitoring TCaM’s effect on clusters of RyR2 channels (which we have shown to act in a concerted manner), using droplet interface bilayer technology and total internal reflection fluorescence imaging, which allows simultaneous measurement of channel proximity and function. Finally, investigation of the effects of TCaM on Ca²⁺ release in mouse ventricular myocytes will act to confirm the effects observed are reflected in a physiological model of arrhythmia. This study will allow the therapeutic potential of TCaM to be assessed and compared with current pharmacological therapies that target RyR2. 

As a PhD student, you will gain multidisciplinary expertise across a broad range of techniques. This will include molecular biology and cell culture for protein expression and purification, single channel recording and electrophysiology for ion channel gating, and artificial membranes to characterise RyR2 behaviour at different scales from in vitro systems to complex live cell studies. The advanced microscopy techniques employed in the project will allow you to gain skills in cellular Ca²⁺ and dynamic single molecule imaging, and you will have the opportunity to develop data analysis skills, applying data science approaches to the large datasets generated in the course of the research. Collectively these skills are highly transferable and in demand across academia and industry, as well as other sectors such as data science. The supervisory team have an excellent track record of project co-supervision and will collectively provide a stimulating, supportive and diverse environment in which to learn and develop as a researcher. You will take part in weekly group meetings and be encouraged to undertake engagement activities and attend conferences to showcase your work and form collaborations, allowing us to support you in securing your own funding, enhancing your research career.

How to apply:

You can apply online – consideration is automatic on applying for a PhD with an October 2025 start date.

Please use our online application service at: https://www.cardiff.ac.uk/study/postgraduate/research/programmes/programme/pharmacy

and specify in the funding section that you wish to be considered for WHRI funding.

Please also specify the project title and supervisor

The closing date for applications is 24th March 2025 and we expect interviews to be held in April/May