Regulation of mitochondrial potassium BKCa channel by naringenin derivatives: application of a new cellular model

Mitochondrial potassium (mitoK) channels play a crucial role in mitochondrial and cellular physiology. One of the best described mitoK channels is the mitochondrial large-conductance calcium-activated potassium (mitoBK Ca ) channel. It has been shown that activation of the mitoBK Ca channel protects the heart and brain tissue against ischemia/reperfusion injury. This channel may be formed in mitochondria by the VEDEC isoform of the α subunit encoded by the KCNMA1 gene. Additionally, to regulation by canonical channel blockers and potassium channel openers, this channel is regulated by flavonoids, including naringenin. Our work aimed to establish and use a new cellular model to investigate the role of new naringenin derivatives in regulating the activity of the mitoBK Ca channel. We developed HEK293 cells stably expressing the VEDEC isoform of the BK Ca (HEK293-BK_DEC). Using the patch-clamp technique on isolated mitoplasts from the newly established cell line, we detected the activity of a potassium channel exhibiting all the characteristics of the mitoBK Ca channel, such as a conductance of 289 pS, voltage-dependent changes in opening probability, channel activation by calcium ions, and inhibition by paxilline. Additionally, introducing the VEDEC isoform into HEK293 cells led to an increase in the mitochondrial oxygen consumption rate and a change in the expression of certain genes encoding mitochondrial proteins involved in oxidative phosphorylation. Subsequently, we investigated the influence of new naringenin derivatives on the activity of the mitoBK Ca channel. We observed that depending on the type of modification of this flavonoid, the channel could be activated or inhibited by the tested naringenin derivatives. In summary, we have developed a new experimental model enabling the study of mitoK channel activity with a defined molecular structure exemplified by the mitoBK Ca channel. This model can be used to test new modulators of the mitochondrial potassium channels, which could be employed for further physiological studies in the future. • Stable expression of VEDEC isoform in HEK293 cells results in mitoBK Ca channel activity • MitoBK Ca alters respiration and gene expression, suggesting a role in cell metabolism • Modifications of naringenin affect its ability to modulate the mitoBK Ca channel