[Effects of peroxisome proliferators-activated receptor gamma agonists on transforming growth factor-beta1 and Smads signal pathway: experiment with rat renal fibroblasts].

Abstract

OBJECTIVE:

To study the effects of peroxisome proliferators-activated receptor gamma (PPARgamma) agonists on transforming growth factor (TGF)-beta1-induced fibrotic responses in renal fibroblasts, so as to investigate its effects in prevention of tubulointerstitial fibrosis.

METHODS:

Rat renal fibroblasts of the line NRK/49F were cultured and divided into groups. In group 1 TGFbeta1 of the concentrations of 0, 1, 2, 5, and 10 ng/ml was added and co-cultured for 24 h. In group 2 TGFbeta1 of the concentration of 5 ng/ml was added and co-cultured for 0, 6, 12, and 24 h respectively. Groups 3, 4, and 5 were pretreated with 10 micromol/L15d-PGJ2, PPARgamma ligand, 10 micromol/L troglitazone, agonist of, and 10 micromol/L ciglitazone, both PPARgamma agonists, respectively for 2 h, then treated with 5 ng/ml TGFbeta1. A blank control group was set up. The cultured cells were collected. RT-PCR was used to detect the mRNA expression of TGF-beta1-indued fibronectin (FN). Western blotting was used to detect the expression of TGF-beta1-induced FN, Smad, and phosphorylated Smad (p-Smad) proteins.

RESULTS:

TGF-beta1 enhanced the FN mRNA expression in a dose- and time-dependent manner. The FN mRNA expression of the 5 ng/ml TGF-beta1 group was 3.7 times that of the control group (P < 0.05). The FN mRNA expression of the 15d-PGJ2, troglitazone-, and ciglitazone-pretreated groups were lower than that of the 5 ng/ml TGF-beta1 group by 37.3%, 41.5%, and 22.7% respectively (all P < 0.05). The p-Smad2/3 protein expression levels of the TGF-beta1 group began to increase 15 minutes after stimulation, increased in a time-dependent manner, peaked 1 hour after, and began to decrease 2 hours later. However, the levels of protein expression of total Smad2 and Smad3 did not change significantly in all groups. Both 2 ng/ml TGFbeta1 and 5 ng/ml TGFbeta1 significantly induced the increase of protein expression of p-Smad2/3 (all P < 0.05). The levels of protein expression of p-Smad2 and p-Smad3 of the 5 ng/ml TGFbeta1 group were 3.42 and 0.97 times those of the 2 ng/ml TGFbeta1 (both P < 0.05). The levels of protein expression of p-Smad2/3 of the 15d-PGJ2, troglitazone-, and ciglitazone-pretreated groups were all significantly lower than that of the 5 ng/ml TGFbeta1 group by 61.2%, 53.0%, and 59.5% (all P < 0.05), However, there was no significant difference among different drug-treated groups (all P > 0.05).

CONCLUSION:

Possibly through abrogating TGF-beta1/Smads signaling pathway, PPARgamma agonists inhibit TGF-beta1-induced renal fibroblast extracellular matrix synthesis and may play a potential role in preventing tubulointerstitial fibrosis as a novel approach to prevent the progress of end stage renal dysfunction.

• Authors: Wei-ming Wang, Feng Liu, Nan Chen
• Journal: Zhonghua yi xue za zhi (Zhonghua Yi Xue Za Zhi) Vol. 86 Issue 11 Pg. 740-4 (Mar 21 2006) ISSN: 0376-2491 [Print] China
• PMID: 16681946 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Chromans
• Extracellular Matrix Proteins
• Fibronectins
• Peroxisome Proliferator-Activated Receptors
• RNA, Messenger
• Smad Proteins
• Thiazolidinediones
• Transforming Growth Factor beta
• betaIG-H3 protein
• 9-deoxy-delta-9-prostaglandin D2
• Troglitazone
• Prostaglandin D2
• ciglitazone

Topics

• Animals
• Blotting, Far-Western
• Cells, Cultured
• Chromans (pharmacology)
• Dose-Response Relationship, Drug
• Extracellular Matrix Proteins (pharmacology)
• Fibroblasts (cytology, drug effects, metabolism)
• Fibronectins (genetics, metabolism)
• Kidney (cytology)
• Peroxisome Proliferator-Activated Receptors (agonists)
• Prostaglandin D2 (analogs & derivatives, pharmacology)
• RNA, Messenger (genetics)
• Rats
• Reverse Transcriptase Polymerase Chain Reaction
• Signal Transduction (drug effects)
• Smad Proteins (genetics, metabolism)
• Thiazolidinediones (pharmacology)
• Transforming Growth Factor beta (pharmacology)
• Troglitazone