Effects of indoxyl sulfate on adherens junctions of endothelial cells and the underlying signaling mechanism.
Uremic patients have a much higher risk of cardiovascular diseases and death. Uremic toxins are probably involved in the development of vascular endothelial dysfunction. Indoxyl sulfate (IS) is a uremic toxin that accumulates with deterioration of renal function. This study explored the effects of IS on the adherens junctions of vascular endothelial cells and revealed the underlying mechanism. Bovine pulmonary artery endothelial cells (BPAECs) were treated with IS, and the distribution of vascular endothelial cadherin (VE-cadherin), p120-catenin, β-catenin, and stress fibers was examined by immunofluorescence. IS treatment resulted in disruption of intercellular contacts between BPAECs with prominent parallel-oriented intracellular stress fiber formation. Intracellular free radical levels which measured by flow cytometry increased after IS treatment. The antioxidant, MnTMPyP, and an ERK pathway inhibitor, U0126, both significantly prevented IS-induced disruption of intercellular contacts. Western blotting analyses demonstrated that IS-induced phosphorylation of myosin light chain kinase (MLCK) and myosin light chains (MLC) as well as activation of extracellular-signal-regulated protein kinase (ERK1/ERK2). Pretreatment with MnTMPyP prevented ERK1/2 phosphorylation. U0126 prevented the IS-induced MLCK and MLC phosphorylation. MEK-ERK acted as the upstream regulator of the MLCK-MLC pathway. These findings suggest that the superoxide anion-MEK-ERK-MLCK-MLC signaling mediates IS-induced junctional dispersal of BPAECs.
Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Yu-Sen
YS
Peng
Yen-Tung
YT
Lin
Ying
Y
Chen
Kuan-Yu
KY
Hung
Seu-Mei
SM
Wang
D022005:Adherens Junctions / Q000187:drug effects* / Q000648:ultrastructure; D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007200:Indican / Q000494:pharmacology*; D020935:MAP Kinase Signaling System; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
D002070:Butadienes; D018994:Myosin Light Chains; D009570:Nitriles; C113580:U 0126; D013481:Superoxides; D009219:Myosin-Light-Chain Kinase; D048049:Extracellular Signal-Regulated MAP Kinases; D007200:Indican