ERK 1/2 Mediates H2O2‐Induced Increase in Renal Epithelial Paracellular Permeability

Abstract

The paracellular permeability of renal epithelia is determined primarily by the integrity of the tight junction (TJ) structure located at the apicolateral borders of adjacent epithelial cells. Treatment of confluent populations of MDCK cells (distal tubule‐like) and LLC‐PK1 cells (proximal tubule‐like) with hydrogen peroxide (H2O2) increases the paracellular permeability to large solutes in a concentration‐dependent manner. H2O2 was cytotoxic at higher concentrations. We have examined the involvement of Mitogen‐Activated Protein Kinases (MAPKs) in mediating these H2O2 actions. Treatment with H2O2 increased the phosphorylation (activation) of multiple MAPKs, ERK ½, JNK ½, and p38MAPK, in a time‐dependent manner. Phosphorylation of each MAPK peaked at 10‐30 minutes and declined by 120 minutes. Pretreatment of cells with U0126 or PD98059, inhibitors of ERK ½ activation, blocked the ability of H­2O2 to increase paracellular permeability. SB202190, a p38MAPK inhibitor, diminished but did not entirely block the H2O2 effect. Treatment of cells with SP600125, an inhibitor of JNK ½ activation, did not affect the ability of H2O2 to increase paracellular permeability. Pretreatment with U0126 and SB202190, but not SP600125, also diminished the cytotoxicity observed at higher H2O2 concentrations. These results indicate that MAPKs, in particular ERK ½, have a central role in mediating the effects of H2O2 on both modulation of paracellular permeability and induction of cytotoxicity in renal epithelial cells. (supported by NIH 1R15DK091749)