Inhibition of plasminogen activator inhibitor type-1 expression in HepG2 cells by fenofibrate may be associated with Smad signaling.
BACKGROUND
We investigated the molecular mechanism underlying the effect of fenofibrate on expression of plasminogen activator inhibitor type-1 (PAI-1) in HepG2 cells.


METHODS
Luciferase reporter gene plasmids containing four sequentially truncated fragments of the PAI-1 promoter region (-804 to +17) were constructed and plasmids carrying constructs of Smad binding element (SBE)-site-directed deletions in the PAI-1 promoter were also generated and then transfected to HepG2 cells prior to fenofibrate treatment. Smad3 and Smad4 protein levels were measured by Western blotting.


RESULTS
The decreased expression of PAI-1 mRNA and protein was detected in HepG2 cells after exposure to fenofibrate. PAI-1 transcription activities were also down-regulated following exposure to fenofibrate in HepG2 cells when they were transfected with the luciferase reporter gene plasmid containing a full-length of PAI-1 promoter. However, with the truncation of PAI-1 promoter, the inhibitory effect of fenofibrate on the transcription activity of PAI-1 gradually diminished. Furthermore, the transcription activity of PAI-1 was significantly up-regulated by fenofibrate in HepG2 cells when they were transfected with plasmids of the SBEs-deleted PAI-1 promoter. The expression of both Smad3 and Smad4 proteins was suppressed by fenofibrate.


CONCLUSIONS
Fenofibrate exerts its inhibitory effect on PAI-1 transcription in HepG2 cells presumably involving Smad signaling pathways.
Chen
Jing
J
Department of Geriatric Cardiology, Chinese PLA General Hospital, Beijing 100853, China.
Ye
Ping
P
Liu
Yong-Xue
YX
Sheng
Li
L
Han
Chun-Guang
CG
He
Yan-Li
YL
D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D011345:Fenofibrate / Q000494:pharmacology*; D006801:Humans; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D051785:Smad Proteins / Q000378:metabolism*; D014158:Transcription, Genetic
D017931:DNA Primers; D017395:Plasminogen Activator Inhibitor 1; D051785:Smad Proteins; D011345:Fenofibrate