How pathological mutations and drugs alter the intracellular movements of the cardiac sodium channel (Nav1.5).

ended

The sodium voltage-gated ion channel Nav1.5 is a key player in shaping the cardiac action potential. Hundreds of pathological mutations that lead to the dysfunction of Nav1.5 are linked to severe pathologies, such as life-threatening arrythmias. The function of these channels is based on precise voltage-dependent molecular motions that result in the opening and closing of their sodium-conducting pore. Despite very recent advances in determining their atomic structure, knowledge of the dynamics of these conformational changes is still lacking. Similarly, it is unknown how pathological mutations, clinically used drugs or post-translational mutations affect these changes. In this project, I therefore propose to – for the first time - decipher the dynamic motions of the Nav1.5 intracellular domains by combining the measurement of the functional state of Nav1.5 through electrophysiology with fluorescent sensor recordings of the motions via voltage-clamp fluorometry. The challenge of establishing a fluorescent sensor on the intracellular domains of Nav1.5 will be overcome by the generation of semi-synthetic Nav1.5 that are engineered to contain a fluorescent dye via tandem protein trans-splicing. The probed motions will be then interrogated in the presence and absence of pathological mutations, drugs and post-translational modifications, such as phosphorylation. This will yield unprecedented insight into their mechanisms of action and will help to propose new ways of targeting the regulation of Nav1.5. This novel approach will therefore have direct implications for the future treatments of patients with cardiac arrhythmias. This innovative project, in an international environment, at the interface of biophysics, fluorescence, pharmacology and peptide synthesis, will also help me deepen my scientific, transversal skills and maturity. This in turn will provide me with the maturity required to become a team leader of my own research group.