Rho GTPase signaling regulates tight junction assembly and protects tight junctions during ATP depletion

Abstract

Tight junctions control paracellular permeability and cell polarity. Rho GTPase regulates tight junction assembly, and ATP depletion of Madin-Darby canine kidney (MDCK) cells (an in vitro model of renal ischemia) disrupts tight junctions. The relationship between Rho GTPase signaling and ATP depletion was examined. Rho inhibition resulted in decreased localization of zonula occludens-1 (ZO-1) and occludin at cell junctions; conversely, constitutive Rho signaling caused an accumulation of ZO-1 and occludin at cell junctions. Inhibiting Rho before ATP depletion resulted in more extensive loss of junctional components between transfected cells than control junctions, whereas cells expressing activated Rho better maintained junctions during ATP depletion than control cells. ATP depletion and Rho signaling altered phosphorylation signaling mechanisms. ZO-1 and occludin exhibited rapid decreases in phosphoamino acid content following ATP depletion, which was restored on recovery. Expression of Rho mutant proteins in MDCK cells also altered levels of occludin serine/threonine phosphorylation, indicating that occludin is a target for Rho signaling. We conclude that Rho GTPase signaling induces posttranslational effects on tight junction components. Our data also demonstrate that activating Rho signaling protects tight junctions from damage during ATP depletion.

RETRACTED: S1P 3 receptor-induced reorganization of epithelial tight junctions compromises lung barrier integrity and is potentiated by TNF

“…Overexpression of constitutively active or dominant-negative RhoA results in striking morphological alterations, such as a loss of the normal tight junction strand morphology (48), whereas Rho activation in MDCK cells results in a selective increase in paracellular permeability of low-molecular-weight tracers (49). It is likely that receptor subtype distribution between cells as well as variations in tight junctions regulation by Rho through effectors like ROCKI varies among lung cells (44,47,(49)(50)(51)(52).…”

Purinergic signalling in the kidney in health and disease

“…ATP depletion of MDCK cells has been used as an in vitro model of renal ischaemia and Rho GTPase signalling shown to regulate tight junction assembly and protect tight junctions during ATP depletion [110]. It has been claimed that in renal ischaemia, the ATP depletion-induced alteration in membrane transport function and cell viability are due to reactive oxygen species generation and cytosolic PLA 2 activation in proximal tubular cells [209].…”

The Biology of Epithelial Cell Tight Junctions in the Kidney

“…RhoA activation with injury protects the TJ and actin cytoskeleton and in combination with tyrosine phosphorylation is a necessary step for TJ recovery. 31 Genetic studies also reveal that claudins are important in both renal and extrarenal diseases. In addition to mutations in CLD-16 and -19 leading to familial hypomagnesemia with hypercalciuria and nephrocalcinosis, some polymorphisms in CLD-14 associate with increased risk of nephrolithiasis, and recessive nonsyndromic deafness results from CLD-14 mutations.…”