Src Family Protein Tyrosine Kinase Regulates the Basolateral K Channel in the Distal Convoluted Tubule (DCT) by Phosphorylation of KCNJ10 Protein

Abstract

Background: KCNJ10 is a key component of the basolateral K channels in DCT. Results: SFK phosphorylates KCNJ10 at Tyr

Caveolin-1 Deficiency Inhibits the Basolateral K+ Channels in the Distal Convoluted Tubule and Impairs Renal K+ and Mg2+ Transport

“…Kcnj10, at least in part, by facilitating the phosphorylation of Kcnj10 at Tyr. 9 After demonstrating that cav-1 was required for the effect of SFK on Kcnj10 in a cell model, we further explored the role of cav-1 in the regulation of Kcnj10 in cav-1 KO mice. If cav-1 is required for facilitating the stimulatory effect of SFK on the basolateral 40 pS K + channel, the disruption of cav-1 should mimic the effect of SFK inhibition and decrease the 40 pS K + channel activity in the basolateral membrane of the DCT.…”

“…9 We next examined whether cav-1 was also required for the effect of PP1, an inhibitor of SFK, on Kcnj10. We performed the perforated whole-cell recording in HEK293T cells transfected with Kcnj10 or Kcnj10+cav-1.…”

“…Our previous study demonstrated that c-Src phosphorylated Kcnj10 and that the inhibition of src-family protein tyrosine kinase (SFK), a family of c-Src-like tyrosine kinase, 22 decreased the basolateral 40 pS K + channel activity in DCT1. 9 Therefore, we next examined whether cav-1 was required for the stimulatory effect of c-Src on Kir.4.1 in Kcnj10-transfected HEK293T cells with the perforated whole-cell recording. Figure 2A shows a set of typical recording of Ba 2+ -sensitive K + currents measured in the cells transfected with Kcnj10, Kcnj10+c-Src, Kcnj10+cav-1, and Kcnj10+cav-1+c-Src.…”

“…Previous study showed that SFK activated Kcnj10 by stimulating tyrosine phosphorylation at Tyr. 9 To examine whether the mutation of Tyr 9 could affect cav-1-induced synergistic effect on SFK-induced stimulation of Kcnj10, we performed the experiments in the cells transfected with Kcnj10 Y9F in which the tyrosine phosphorylation site was mutated. Kcnj10, at least in part, by facilitating the phosphorylation of Kcnj10 at Tyr.…”

“…6,7 Previous studies have identified a 40 pS inwardly rectifying K + channel in the basolateral membrane of the DCT. 8,9 This 40 pS K + channel is a heterotetramer of Kir4.1 and Kir5.1 because the coexpression of Kir4.1/5.1 produced an inwardly rectifying K + channel with the same biophysical properties as the 40 pS K + channel expressed in the basolateral membrane of the native DCT. [10][11][12] The role of Kir4.1 in forming the basolateral 40 pS K + channel of the DCT was convincingly demonstrated by the observation that the disruption of Kcnj10 (Kir.4.1) completely eliminated the 40 pS K + channel.…”