title: RhoA and Rho kinase mediate cyclosporine A and sirolimus-induced barrier tightening in renal proximal tubular cells.
abstract: The regulation and maintenance of the paracellular transport in renal tubular epithelia is vital for kidney functions. Combination of the immunosuppressant drugs cyclosporine A (CsA) and sirolimus (SRL) exerts powerful immunosuppression, but also causes nephrotoxicity. We have previously shown that CsA and SRL elevate transepithelial resistance (TER) in kidney tubular cells partly through MEK/ERK1/2. In this work we examined the hypothesis that the RhoA pathway may also be mediating effects of CsA and SRL. We show that CsA and the CsA/SRL combination activated RhoA, induced cofilin phosphorylation and promoted stress fiber generation. The Rho kinase (ROK) inhibitor, Y27632, prevented CsA and CsA/SRL-induced cofilin phosphorylation and actin remodelling, reduced the TER increase and prevented the rise in claudin-7 levels caused by the drugs. Expression of the exchange factor GEF-H1/lfc was elevated in cells treated with CsA and CsA/SRL. GEF-H1 silencing inhibited RhoA activation by ≈50%, and potently reduced cofilin phosphorylation and stress fiber formation induced by CsA and CsA/SRL. However, GEF-H1 downregulation did not prevent the TER change. Thus the Rho/Rho kinase pathway was involved in mediating CsA and CsA/SRL-induced cytoskeleton rearrangement and TER changes via claudin-7 expression. Our data however point to differential regulation of Rho activation involved in central cytoskeleton remodelling, that is GEF-H1-dependent and junctional permeability that does not require GEF-H1.
authors: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
authors: Natalia
authors: N
authors: Martin-Martin
authors: Qinghong
authors: Q
authors: Dan
authors: Yasaman
authors: Y
authors: Amoozadeh
authors: Faiza
authors: F
authors: Waheed
authors: Tara
authors: T
authors: McMorrow
authors: Michael P
authors: MP
authors: Ryan
authors: Katalin
authors: K
authors: Szászi
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D004847:Epithelial Cells / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000201:enzymology; D021381:Protein Transport; D020123:Sirolimus / Q000494:pharmacology*; D013552:Swine; D019108:Tight Junctions / Q000187:drug effects / Q000201:enzymology; D015854:Up-Regulation; D054460:rho-Associated Kinases / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D016572:Cyclosporine; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D020123:Sirolimus