Epithelial Na+ channel (ENaC) activity, which determines the rate of renal Na+ reabsorption, can be regulated by G-protein coupled receptors. Regulation of ENaC by Gα mediated downstream effectors has been studied extensively, but the effect of Gβγ dimers on ENaC is unclear. A6 cells endogenously contain high levels of Gβ1 but low levels of Gβ3 ,Gβ4 and Gβ5 were detected by Q-PCR. We tested Gγ2 combined individually with Gβ1 through Gβ5 expressed in A6 cells, after which we recorded single ENaC activity. Among the five β and γ2 combinations, β1γ2 strongly inhibits ENaC activity by reducing both ENaC channel number (N) and open probability (Po) compared to control cells. In contrast, the other four β isoforms combined with γ2 have no significant effect on ENaC activity. By using various inhibitors to probe Gβ1γ2 effects on ENaC regulation, we found that Gβ1γ2-mediated ENaC inhibition involved activation of phospholipase C-β and its enzymatic products that induce protein kinase C and ERK1/2 signaling pathways.
- G protein beta-gamma subunits,
- phospholipase C
- protein kinase C
- Copyright © 2013, American Journal of Physiology - Renal Physiology