Larsson, H. P. | Search bioRxiv

bioRxiv2023

Mechanistic insights into robust cardiac IKs potassium channel activation by aromatic polyunsaturated fatty acid analogues

Voltage-gated potassium (KV) channels are important regulators of cellular excitability and control action potential repolarization in the heart and brain. KV channel mutations lead to disordered cellular excitability. Loss-of-function mutations, for example, result in membrane hyperexcitability, a characteristic of epilepsy and cardiac arrhythmias. Interventions intended to restore KV channel function have strong therapeutic potential in such disorders. Polyunsaturated fatty acids (PUFAs) and PUFA analogues comprise a class of KV channel activators with potential applications in the treatment of arrhythmogenic disorders such as Long QT Syndrome (LQTS). LQTS is caused by a loss-of-function of the cardiac IKs channel - a tetrameric potassium channel complex formed by KV7.1 and associated KCNE1 protein subunits. We have discovered a set of aromatic PUFA analogues that produce robust activation of the cardiac IKs channel and a unique feature of these PUFA analogues is an aromatic, tyrosine head group. We determine the mechanisms through which tyrosine PUFA analogues exert strong activating effects on the IKs channel by generating modified aromatic head groups designed to probe cation-pi interactions, hydrogen bonding, and ionic interactions. We found that tyrosine PUFA analogues do not activate the IKs channel through cation-pi interactions, but instead do so through a combination of hydrogen bonding and ionic interactions.

physiology↗

bioRxiv2019

Polyunsaturated fatty acid analogues differentially affect cardiac Nav, Cav, and Kv channels through unique mechanisms

The cardiac ventricular action potential depends on several voltage-gated ion channels, including Nav, Cav, and Kv channels. Mutations in these channels can cause Long QT Syndrome (LQTS) which increases the risk for ventricular fibrillation and sudden cardiac death. Polyunsaturated fatty acids (PUFAs) have emerged as potential therapeutics for LQTS because they are modulators of voltage-gated ion channels. Here we demonstrate that PUFA analogues vary in their selectivity for human voltage-gated ion channels involved in the ventricular action potential. The effects of specific PUFA analogues range from selective for a specific ion channel to broadly modulating all three cardiac ion channels (NaV, CaL, and IKs). In addition, PUFA analogues do not modulate these channels through a shared mechanism. Our data suggest that different PUFA analogues could be tailored towards specific forms of LQTS, which are caused by mutations in distinct cardiac ion channels, and thus restore a normal ventricular action potential.

biophysics↗