title: Sirolimus and cyclosporine A alter barrier function in renal proximal tubular cells through stimulation of ERK1/2 signaling and claudin-1 expression.
abstract: Alteration of the tight junction complex in renal epithelial cells can affect renal barrier function and perturb normal kidney homeostasis. The immunosuppressant drugs cyclosporine A (CsA) and sirolimus (SRL) used in combination demonstrated beneficial effects in organ transplantation but this combination can also result in increased adverse effects. We previously showed that CsA treatment alone caused an alteration of the tight junction complex, resulting in changes in transepithelial permeability in Madin-Darby canine kidney distal tubular/collecting duct cells. The potential effect of SRL on transepithelial permeability in kidney cells is unknown. In this study, subcytotoxic doses of SRL or CsA were found to decrease the paracellular permeability of the porcine proximal tubular epithelial cells, LLC-PK1 cell monolayers, which was detected as an increase in transepithelial electrical resistance (TER). The cotreatment with SRL and CsA was found to increase TER in a synergistic manner. CsA treatment increased total cellular expression and membrane localization of the tight junction protein claudin-1 and this further increased with the combination of SRL/CsA. SRL and CsA treatment alone or in combination stimulated the phosphorylation of ERK1/2. The MEK-ERK1/2 pathway inhibitor, U0126, reduced the SRL, CsA, and CsA/SRL-induced increase in TER. U0126 also reduced the CsA and CsA/SRL-induced increase in the membrane localization of claudin-1. Alterations in claudin-2 and claudin-4 were also detected. However, the results suggest that the modulation in expression and localization of claudin-1 appears to be pivotal in the SRL- and CsA-induced modulation of the epithelial barrier function and that modulation is regulated by ERK1/2 signaling pathway.
authors: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland.
authors: Natalia
authors: N
authors: Martin-Martin
authors: Gavin
authors: G
authors: Ryan
authors: Tara
authors: T
authors: McMorrow
authors: Michael P
authors: MP
authors: Ryan
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D062445:Claudin-1; D062506:Claudin-4; D016572:Cyclosporine / Q000633:toxicity*; D004357:Drug Synergism; D017097:Electric Impedance; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D007166:Immunosuppressive Agents / Q000633:toxicity*; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000201:enzymology; D018374:LLC-PK1 Cells; D008565:Membrane Proteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010539:Permeability; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000633:toxicity*; D013552:Swine; D019108:Tight Junctions / Q000187:drug effects / Q000201:enzymology; D013997:Time Factors
chemical_list: D002070:Butadienes; D062445:Claudin-1; D062506:Claudin-4; D007166:Immunosuppressive Agents; D008565:Membrane Proteins; D009570:Nitriles; D047428:Protein Kinase Inhibitors; C113580:U 0126; D016572:Cyclosporine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020123:Sirolimus