P2Y receptor regulation of apical K2P channels involved in K secretion by human mammary epithelial cells

Abstract

In this study, the molecular identity and regulation of ion channels involved in K+ secretion by human mammary epithelial cells was investigated. Voltage clamp experiments were performed on human mammary epithelial monolayers basolaterally treated with the pore‐forming antibiotic amphotericin B dissolved in a solution with intracellular ionic composition. Addition of benzamil to the apical solution inhibited the basal current, consistent with inhibition of sodium absorption. Moreover, apical addition of the K2P channel blockers quinidine, bupivacaine and a selective TASK1/TASK3 inhibitor (PK‐THPP) all produced concentration‐dependent increases in apical membrane current resulting from inhibition of apical K+ efflux. Expression of mRNA for nine K2P channel subtypes was demonstrated by qRT‐PCR. Western blots using biotinylated apical membranes and confocal immunocytochemistry showed that TWIK1, TREK1, TREK2, TASK1 and TASK3 were all located in the apical membrane. Purinergic receptor stimulation with apical UTP also increased apical membrane current, however pretreatment with GF109203X, a pan‐selective inhibitor of PKC, inhibited the effect of UTP. Furthermore, PKC activation with phorbol 12‐myristate 13‐acetate, like UTP, also increased the current. We conclude that basal K+ secretion depends on the activity of multiple K2P channel subtypes, some of which are inhibited by purinergic receptor stimulation and activation of PKC.Support or Funding InformationThis study supported by a Royal Golden Jubilee PhD program Fellowship from The Thailand Research Fund (PHD/0204/2551) to YS and CD and by the NIH (R01 AI128729‐01) to SMO.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.