Poster: 161With-No-Lysine Kinases Coordinate Cl– secretion across human airway epithelia

V. Srivastava; A. Attar; I. Thornell

doi:10.1016/j.jcf.2026.07.192

Airway epithelia secrete Cl– through a coordinated action of channels and transporters. This coordination is required for optimal airway host defense, as evidenced by its dysfunction in cystic fibrosis (CF). CF is caused by the failure of the cystic fibrosis transmembrane conductance regulator (CFTR) to conduct anions across the apical membrane of airway epithelia. While this channel is central to CF research, other channels and transporters are required to sustain favorable driving forces for Cl– secretion. For example, increasing Cl– secretion across airway epithelia does not change the intracellular [Cl–], indicating that during secretion, the increased flow of Cl– exiting the cell through apical CFTR channels is perfectly matched by an increase in Cl– flow into the cell through the basolateral membrane. We hypothesized that secretory flow of Cl– through CFTR is limited by Cl– entering the cell through the basolateral membrane Cl– transporter NKCC1. In airway epithelia, CFTR exists in at least two pathways for ion flow: a purely secretory pathway that consists of CFTR and NKCC1, and, in ionocytes, in series with a basolateral Cl– channel and NKCC1. To determine which pathways are involved in generating short-circuit current, we produced epithelia without ionocytes by disrupting the FOXI1 gene. Ionocytes comprised around 0.5-1% of epithelial cells, and their removal did not alter short-circuit current compared to controls, suggesting that the majority of short-circuit current in human airway epithelia is generated by non-ionocytes. The bumetanide-sensitive relationship between basolateral [Cl–] and short-circuit current was sigmoidal, indicating that Cl– flow followed the kinetics of NKCC1 (with low- and high-affinity binding sites) rather than CFTR (with Michaelis-Menten kinetics). With-no-lysine kinases (WNK) are Cl–-sensitive and may mediate crosstalk between the apical and basolateral membranes during ion transport. We found that the relationship between [WNK-463] (a WNK inhibitor) and Isc had an IC50 of 180 nM. Thus, WNK coordinates the crosstalk between the apical and basolateral membranes, thereby adjusting NKCC1 activity to support CFTR activity.

Poster: 161With-No-Lysine Kinases Coordinate Cl– secretion across human airway epithelia

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