Mediating effects of aryl-hydrocarbon receptor and RhoA in altering brain vascular integrity: the therapeutic potential of statins.
We have demonstrated previously that focal adhesion kinase (FAK)/RhoA alteration by the aryl-hydrocarbon receptor (AhR) agonist 3-methylcholanthrene (3MC) is involved in the antimigratory effects of 3MC in human umbilical vascular endothelial cells. Here, we identified that signaling properties and molecular mechanisms of RhoA/β-catenin were both implicated in alterations to blood-brain barrier integrity. The mechanisms of action were the down-regulation of integrin, the extracellular matrix, and adherens junction stability. PTEN phosphorylation by 3MC-mediated AhR/RhoA activation increased the proteasomal degradation of β-catenin through PKCδ/pGSK3β-mediated β-catenin phosphorylation; the crucial roles of AhR/RhoA in this process were verified by using gain- or loss-of-function experiments. The decrease in β-catenin led to decreased expression of fibronectin and α5β1 integrin. Additionally, protein interactions among FAK, VE-cadherin, vinculin, and β-actin were simultaneously decreased, resulting in adherens junction instability. Novel functional TCF/LEF1 binding sites in the promoter regions of fibronectin and α5/β1 integrin were identified by electrophoretic mobility shift and chromatin immunoprecipitation assays. The results indicate that the binding activities of β-catenin decreased in mouse cerebrovascular endothelial cells treated with 3MC. In addition, simvastatin and pravastatin treatment reversed 3MC-mediated alterations in mouse cerebrovascular endothelial cells by RhoA inactivation, and the in vitro findings were substantiated by an in vivo blood-brain barrier assay. Thus, endothelial barrier dysfunction due to 3MC occurs through AhR/RhoA-mediated β-catenin down-regulation, which is reversed by simvastatin treatment in vivo.
Graduate Institute of Medical Sciences, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Chih-Cheng
CC
Chang
Pei-Shan
PS
Lee
Ying
Y
Chou
Ling-Ling
LL
Hwang
Shu-Hui
SH
Juan
D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000502:physiology; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D039081:Integrin alpha5beta1 / Q000378:metabolism; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding / Q000187:drug effects; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists / Q000502:physiology*; D051176:beta Catenin / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D020742:rhoA GTP-Binding Protein
D005353:Fibronectins; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D039081:Integrin alpha5beta1; D018336:Receptors, Aryl Hydrocarbon; D051176:beta Catenin; D008748:Methylcholanthrene; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse; C526380:RhoA protein, mouse; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein