Harnessing the molecular-scale resolution of DNA-PAINT to study the structural basis of electrical signals of the healthy and arrhythmic hearts

Single molecule localisation microscopy (SMLM) has revolutionised our understanding of signalling microdomains in many biological systems. Among such molecular systems are arrays of gap junction (GJ) channels paving the fundamental electrical signalling pathways of the heart. Conventional SMLMs are unable to visualise individual GJ channels within their native tissue environment because they are limited by resolution. One of the newest SMLM techniques, DNA-PAINT, promises a resolution of about 5nm which is sufficient to resolve single proteins in tightly packed arrays or clusters and to visually observe their interactions with other molecules. However, this technique is not suitable for imaging complex tissues such as the myocardium.

We will implement three possible modifications to the DNA-PAINT protocol to enable in situ optical mapping of GJ isoforms. DNA-PAINT will be further harnessed to quantify the changes in the phosphorylation states of GJ channels in ventricular cardiac tissue that exhibits pathological electrical disturbances known as arrhythmias.

The improved DNA-PAINT protocol and the pilot measurements on GJ remodelling will seed a larger investigation pioneering a direct, in situ, correlation of the GJ nanostructure and disturbed electrical patterns in hearts life-threatening arrhythmias.