Deficiency of the BKCa potassium channel displayed significant implications for the physiology of the human bronchial epithelium

Plasma membrane large-conductance calcium-activated potassium (BK_Ca) channels are important players in various physiological processes, including those mediated by epithelia. Like other cell types, human bronchial epithelial (HBE) cells also express BK_Ca in the inner mitochondrial membrane (mitoBK_Ca). The genetic relationships between these mitochondrial and plasma membrane channels and the precise role of mitoBK_Ca in epithelium physiology are still unclear. Here, we tested the hypothesis that the mitoBK_Ca channel is encoded by the same gene as the plasma membrane BK_Ca channel in HBE cells. We also examined the impact of channel loss on the basic function of HBE cells, which is to create a tight barrier. For this purpose, we used CRISPR/Cas9 technology in 16HBE14o- cells to disrupt the KCNMA1 gene, which encodes the α-subunit responsible for forming the pore of the plasma membrane BK_Ca channel. Electrophysiological experiments demonstrated that the disruption of the KCNMA1 gene resulted in the loss of BK_Ca-type channels in the plasma membrane and mitochondria. We have also shown that HBE ΔαBK_Ca cells exhibited a significant decrease in transepithelial electrical resistance which indicates a loss of tightness of the barrier created by these cells. We have also observed a decrease in mitochondrial respiration, which indicates a significant impairment of these organelles.

In conclusion, our findings indicate that a single gene encodes both populations of the channel in HBE cells. Furthermore, this channel is critical for maintaining the proper function of epithelial cells as a cellular barrier.