SP600125, an inhibitor of c-Jun NH2-terminal kinase, blocks expression of angiotensin II-induced monocyte chemoattractant protein-1 in human mesangial cells.
BACKGROUND
We investigated the role of c-Jun NH2-terminal kinase (JNK), a member of the mitogen-activated protein kinase family, in the expression of angiotensin II (Ang II)-induced monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor-1 (TGF-1), and in the production of fibronectin (FN), by human mesangial cells (HMCs).


METHODS
JNK activation in cultured human mesangial cells was determined by Western blotting with an antibody against the phosphorylated Ser63 residue of c-Jun. Binding of the activator protein (AP-1) to the MCP-1 AP-1 motif was detected via the electrophoretic mobility shift assay (EMSA). The transient luciferase reporter was used to examine MCP-1 promoter activity; an RNase protection assay and ELISA were used respectively to detect the expression of MCP-1 mRNA and production of MCP-1, TGF-beta and FN.


RESULTS
Anthra (1,9-cd) pyrazol-6(2H)-one (SP600125), a pharmacological inhibitor of JNK, almost completely abolished Ang II-induced Ser63 phosphorylation of c-Jun at concentrations of 5-20 micromol/L: JNK activity was reduced by 75% with 10 micromol/L SP600125, and by 90% with 20 micromol/L. Ang II increased AP-1 binding to the MCP-1 AP-1 motif in a time-dependent manner, as detected by EMSA, while SP600125 effectively blocked this increased AP-1 binding in a concentration-dependent manner. Treatment with 100 nmol/L Ang II led to a steady increase in MCP-1 mRNA expression, and to an enhanced production of MCP-1, TGF-beta and FN. These effects were blocked by SP60025 in a dose-dependent manner. SP600125 also reduced MCP-1 mRNA stability: the halflife of MCP-1 mRNA was approximately 5 hours in cells treated with Ang II only, but was reduced to 2 hours when treated with a combination of Ang II and SP600125.


CONCLUSIONS
These results show that the JNK/AP-1 pathway is involved in the expression of MCP-1 and TGF-beta, and in extracellular matrix production. JNK is an important therapeutic target for glomerulonephritis and glomerulosclerosis.
Ding
Gui-Xia
GX
Department of Nephrology, Nanjing Children's Hospital, Affiliated to Nanjing Medical University, Nanjing, Jiangsu, China.
Zhang
Ai-Hua
AH
Huang
Song-Ming
SM
Pan
Xiao-Qin
XQ
Chen
Rong-Hua
RH
D000804:Angiotensin II / Q000494:pharmacology*; D000873:Anthracenes / Q000494:pharmacology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D050527:Mesangial Cells / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
D000873:Anthracenes; D018932:Chemokine CCL2; D005353:Fibronectins; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D000804:Angiotensin II; C432165:pyrazolanthrone; D048031:JNK Mitogen-Activated Protein Kinases