Hydrogen Sulfide Prevents Hydrogen Peroxide-Induced Activation of Epithelial Sodium Channel through a PTEN/PI(3,4,5)P3 Dependent Pathway

Abstract

Sodium reabsorption through the epithelial sodium channel (ENaC) at the distal segment of the kidney plays an important role in salt-sensitive hypertension. We reported previously that hydrogen peroxide (H 2 O 2 ) stimulates ENaC in A6 distal nephron cells via elevation of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P 3 ) in the apical membrane. Here we report that H 2 S can antagonize H 2 O 2 -induced activation of ENaC in A6 cells. Our cell-attached patch-clamp data show that ENaC open probability (P O ) was significantly increased by exogenous H 2 O 2 , which is consistent with our previous finding. The aberrant activation of ENaC induced by exogenous H 2 O 2 was completely abolished by H 2 S (0.1 mM NaHS). Pre-treatment of A6 cells with H 2 S slightly decreased ENaC P O ; however, in these cells H 2 O 2 failed to elevate ENaC P O . Confocal microscopy data show that application of exogenous H 2 O 2 to A6 cells significantly increased intracellular reactive oxygen species (ROS) level and induced accumulation of PI(3,4,5)P 3 in the apical compartment of the cell membrane. These effects of exogenous H 2 O 2 on intracellular ROS levels and on apical PI(3,4,5)P 3 levels were almost completely abolished by treatment of A6 cells with H 2 S. In addition, H 2 S significantly inhibited H 2 O 2 -induced oxidative inactivation of the tumor suppressor phosphatase and tensin homolog (PTEN) which is a negative regulator of PI(3,4,5)P 3. Moreover, BPV (pic) , a specific inhibitor of PTEN, elevated PI(3,4,5)P 3 and ENaC activity in a manner similar to that of H 2 O 2 in A6 cells. Our data show, for the first time, that H 2 S prevents H 2 O 2 -induced activation of ENaC through a PTEN-PI(3,4,5)P 3 dependent pathway.