title: Oxidized LDL induces transcription factor activator protein-1 in rat mesangial cells.
abstract: It has been shown that oxidized low-density lipoprotein (ox-LDL), through the activation of glomerular cells, stimulates pathobiological processes involved in monocyte infiltration into the mesangium. The underlying molecular mechanisms are not fully understood. The present study showed that ox-LDL strongly induced AP-1 binding activity in rat mesangial cells (RMCs) in a dose- and time-dependent manner, reaching the maximal activation at 250 microg ml(-1) within 24 h. The results from mobility shift assays and Western blotting analysis revealed that this AP-1 binding increase involved c-Jun, but not c-Fos. Moreover, this ox-LDL-increased AP-1 binding was inhibited by several protein kinase (PK) inhibitors: the protein kinase C (PKC) inhibitor Bisindolylmaleimide I, the cAMP-dependent PK (PKA) inhibitor H89, and the tyrosine PK (PTK) inhibitor genistein. Protein phosphorylation represents mitogen-activated protein kinase (MAPK) activity. Therefore, we examined the role of ox-LDL on the activation of mesangial cell JNK/SAPK, the only recognized protein kinase that catalyses phosphorylation of c-Jun. The incubation of mesangial cells with ox-LDL induced phosphorylation of JNK1/SAPK dose dependently, with the maximal response at 150 microg ml(-1). This study demonstrates that multiple kinase activities are involved in the mechanism of ox-LDL-induced AP-1 activation in mesangial cells, and ox-LDL stimulates AP-1 through JNK-c-Jun other than MEK-c-Fos signalling pathway.
authors.affiliation: Division of Nephrology, Zhongshan Hospital, Fudan University Shanghai Medical College, Shanghai 200032, People's Republic of China. Professor-wu@yahoo.com.cn
authors.forename: Zhao-Long
authors.initials: ZL
authors.lastname: Wu
authors.forename: Yuan-Cheng
authors.initials: YC
authors.lastname: Wang
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhou
authors.forename: Yu-Qiang
authors.initials: YQ
authors.lastname: Ge
authors.forename: Yang
authors.initials: Y
authors.lastname: Lan
mesh_terms: D051697:Activating Transcription Factor 1; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000494:pharmacology; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008297:Male; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009841:Oligonucleotides / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D051697:Activating Transcription Factor 1; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008077:Lipoproteins, LDL; D009841:Oligonucleotides; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; C099252:oxidized low density lipoprotein; C015482:protein kinase modulator; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases