Connective tissue growth factor is responsible for transforming growth factor-beta-induced peritoneal mesothelial cell apoptosis.
BACKGROUND
Previous studies found that transforming growth factor-beta (TGF-beta) induces mesothelial production of connective tissue growth factor (CTGF), which may be downstream mediators of TGF-beta. Since high dose TGF-beta induces apoptosis of peritoneal mesothelial cells (PMC), we study the effect of CTGF blockade in the system of TGF-beta-induced PMC apoptosis.


METHODS
We examined the effect of TGF-W in primary culture of rat peritoneal mesothelial cells (PMC). PMC apoptosis was studied by flow cytometry. The effect of CTGF was blocked by antibody and short-interfering RNA (siRNA). Expression of apoptotic gene was studied by real-time polymerase chain reaction.


RESULTS
In cultured unstimulated rat PMC, there is a low but definite incidence of spontaneous apoptosis. Stimulation with TGF-beta 50 pg/ml induces an upregulation of apoptotic gene BAX expression and a downregulation of anti-apoptotic gene BCL-2L expression, and a 4-fold increase in PMC apoptosis. The effect of TGF-beta-induced PMC apoptosis was partly prevented by antibody against CTGF, and completely abolished by CTGF-specific siRNA, while CTGF-blockade by siRNA had no effect on PMC necrosis. CTGF silencing by siRNA prevented the down-regulation of BCL-2L expression induced by TGF-beta, had no effect on the BAX expression.


CONCLUSIONS
Our results indicate that CTGF is an important downstream mediator of TGF-beta-induced PMC apoptosis.
Szeto
Cheuk-Chun
CC
Department of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China. ccszeto@cuhk.edu.hk
Chow
Kai-Ming
KM
Lai
Ka-Bik
KB
Szeto
Carol Yi-Ki
CY
Kwan
Bonnie Ching-Ha
BC
Li
Philip Kam-Tao
PK
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D055513:Connective Tissue Growth Factor; D015536:Down-Regulation; D004847:Epithelial Cells / Q000502:physiology*; D005355:Fibrosis; D017874:Immediate-Early Proteins / Q000502:physiology*; D007249:Inflammation; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology*; D010537:Peritoneum / Q000166:cytology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000502:physiology; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C526316:CCN2 protein, rat; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016212:Transforming Growth Factor beta; D051028:bcl-2-Associated X Protein; D055513:Connective Tissue Growth Factor