Document Detail

Oxidized LDL activates PAI-1 transcription through autocrine activation of TGF-beta signaling in mesangial cells.
MedLine Citation:
PMID:  15840021     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Lipid abnormalities and oxidative stress may be involved in the development of glomerulosclerosis. Plasminogen activator inhibitor-1 (PAI-1) is a component of extracellular matrix (ECM) and target gene of transforming growth factor-beta (TGF-beta). Smad proteins play a key role in TGF-beta signaling, and Smad binding CAGA boxes are present in the PAI-1 promoter. This study examined whether oxidized low-density lipoprotein (Ox-LDL) activates PAI-1 transcription in human mesangial cells, mediated by increased Smad/DNA interactions. METHODS: Quiescent HMC were incubated with 50 microg/mL of Cu(++)-catalyzed Ox-LDL for 15 minutes to 4 hours, and the effects of Ox-LDL on TGF-beta1 and PAI-1 mRNA expression, PAI-1 promoter activity, and DNA binding activity of Smad proteins were examined. RESULTS: Ox-LDL induced TGF-beta1 and PAI-1 mRNA expression. Ox-LDL increased the transiently transfected PAI-1 promoter activity as compared with controls to 3.9-fold. Ox-LDL-treated cells increased Smad3 protein levels two times the control levels in the nuclei. Electrophoretic mobility shift assay (EMSA) performed using a CAGA sequence probe and nuclear extracts showed that Ox-LDL increased DNA/protein complexes. When nuclear extracts were preincubated with 100 molar excess of unlabeled CAGA oligonucleotide or SB-431542, an inhibitor of the TGF-beta type I receptor, the formation of complex was prevented. The DNA binding protein was shown to be Smad3 by antibody supershift. Transfection of phosphorothioate CAGA oligonucleotides, which compete with the CAGA-containing PAI-1 promoter for Smad3 binding, inhibited the Ox-LDL-induced PAI-1 mRNA expression. Cotransfection of phosphorothioate CAGA oligonucleotides with PAI-1 reporter vector also blocked the Ox-LDL-induced PAI-1 promoter activity. CONCLUSION: These results suggest that Ox-LDL activates TGF-beta/Smad signaling to stimulate PAI-1 transcription in human mesangial cells. Thus, progression of glomerular disease may be promoted by PAI-1 up-regulation in human mesangial cells mediated by the Ox-LDL-induced TGF-beta/Smad signaling pathways.
Chi Young Song; Bong Cho Kim; Hye Kyoung Hong; Hyun Soon Lee
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Kidney international     Volume:  67     ISSN:  0085-2538     ISO Abbreviation:  Kidney Int.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-04-20     Completed Date:  2005-08-22     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0323470     Medline TA:  Kidney Int     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1743-52     Citation Subset:  IM    
Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
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MeSH Terms
Base Sequence
Binding Sites / genetics
Cells, Cultured
DNA / genetics,  metabolism
DNA-Binding Proteins / metabolism
Glomerular Mesangium / drug effects*,  metabolism*
Lipoproteins, LDL / pharmacology*
Plasminogen Activator Inhibitor 1 / genetics*
Promoter Regions, Genetic
RNA, Messenger / genetics,  metabolism
Signal Transduction / drug effects
Smad3 Protein
Trans-Activators / metabolism
Transcriptional Activation / drug effects
Transforming Growth Factor beta / genetics,  metabolism*
Reg. No./Substance:
0/DNA-Binding Proteins; 0/Lipoproteins, LDL; 0/Plasminogen Activator Inhibitor 1; 0/RNA, Messenger; 0/SMAD3 protein, human; 0/Smad3 Protein; 0/Trans-Activators; 0/Transforming Growth Factor beta; 0/oxidized low density lipoprotein; 9007-49-2/DNA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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