Remodeling of the tight junction during recovery from exposure to hydrogen peroxide in kidney epithelial cells

Abstract

Renal ischemia–reperfusion injury results in oxidative stress-induced alterations in barrier function. Activation of the mitogen-activated protein (MAP) kinase pathway during recovery from oxidative stress may be an effector of oxidant-induced tight junction reorganization. We hypothesized that tight junction composition and barrier function would be perturbed during recovery from oxidative stress. We developed a model of short-term H 2O 2 exposure followed by recovery using Madin Darby canine kidney (MDCK II) cells. H 2O 2 perturbs barrier function without a significant cytotoxic effect except in significant doses. ERK-1/2 and p38, both enzymes of the MAP kinase pathway, were activated within minutes of exposure to H 2O 2. Transient exposure to H 2O 2 produced a biphasic response in the transepithelial electrical resistance (TER). An initial drop in TER at 6 h was followed by a significant increase at 24 h. Inhibition of ERK-1/2 activation attenuated the increase in TER observed at 24 h. Expression of occludin initially decreased, followed by partial recovery at 24 h. In contrast, claudin-1 levels decreased and failed to recover at 24 h. Claudin-2 levels were markedly decreased at 24 h; however, inhibition of ERK-1/2 activation was protective. Occludin and claudin-1 localization at the apical membrane on immunofluorescence images was fragmented at 6 h after H 2O 2 exposure with subsequent recovery of appropriate localization by 24 h. MDCK II cell recovery after H 2O 2 exposure is associated with functional and structural modifications of the tight junction that are mediated in part by activation of the MAP kinase enzymes ERK-1/2 and p38.