AP-1 complexes mediate oxidized LDL-induced overproduction of TGF-β1 in rat mesangial cells
| Autor: | Huiming Jin, Yang Lan, Yuancheng Wang, Qin Zhou, Zhao-Long Wu, Xun‐Hui Xu |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Male
Curcumin Proto-Oncogene Proteins c-jun Recombinant Fusion Proteins Glomerular Mesangial Cell Clinical Biochemistry Regulatory Sequences Nucleic Acid Biology p38 Mitogen-Activated Protein Kinases Biochemistry Rats Sprague-Dawley Transforming Growth Factor beta1 Gene expression Animals Humans RNA Messenger Binding site Promoter Regions Genetic Protein kinase A Protein Kinase C Protein kinase C Sequence Deletion Regulation of gene expression Binding Sites Nuclear Proteins Cell Biology General Medicine Transfection Molecular biology Glomerular Mesangium Rats Lipoproteins LDL Transcription Factor AP-1 Gene Expression Regulation Mutagenesis Site-Directed Signal transduction Signal Transduction |
| Zdroj: | Cell Biochemistry and Function. 22:237-247 |
| ISSN: | 1099-0844 0263-6484 |
| DOI: | 10.1002/cbf.1096 |
| Popis: | Oxidized Low Density Lipoprotein (Ox-LDL)-induced overproduction of the prosclerotic cytokine transforming growth factor-beta1 (TGF-beta(1)) has been implicated in the pathogenesis of renal fibrosis and sclerosis. Because Ox-LDL increases TGF-beta(1) mRNA levels in rat mesangial cells, our investigation was designed to characterize these effects on the rat TGF-beta(1) promoter activity. We transfected luciferase reporter gene constructs containing TGF-beta(1) 5'-flanking sequence (from -1550 to +57 bp) into mesangial cells. By assaying progressively deleted mutations in the promoter, we found two regions that were responsible for the induction. One is a negative regulatory region (-422 to -629) which represses the transcription of the TGF-beta(1) gene, the other is a positive regulatory region (-845 to -1550) which enhances the transcription unit efficiently. There is an activating protein-1(AP-1) binding site in the latter region. Mutagenesis in the AP-1 binding sites abolished the Ox-LDL effect. Furthermore, addition of the AP-1 inhibitor curcumin obliterated the Ox-LDL response. The Ox-LDL-induced TGF-beta(1) promoter activation was also prevented by inhibitors of protein kinase C, but not by p38 mitogen-activated protein kinase. Electrophoretic mobility shift assays with oligonucleotides containing AP-1 binding sites showed that Ox-LDL treatment significantly enhanced the binding activity of nuclear proteins of mesangial cells. Supershift assays demonstrated that c-Jun was present in the protein-DNA complexes under stimulation of Ox-LDL. The functional and structural results show that Ox-LDL regulates rat TGF-beta(1) gene expression through AP-1 binding sites and gives rise to the involvement of protein kinase C in Ox-LDL-induced TGF-beta(1) gene expression. |
| Databáze: | OpenAIRE |
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