[Transforming growth factor beta 1 modulates connective tissue growth factor expression via Smad2 signaling pathway in podocyte in vitro].
OBJECTIVE
To assess the expression of connective tissue growth factor (CTGF), and the signaling pathway for the regulation of CTGF by transforming growth factor beta1 (TGF beta(1)) in podocytes.


METHODS
In this study, we observed the effects of three potent profibrotic growth factors-TGF beta(1), Platelet-derived growth factor (PDGF), and Angiotensin II (AngII) on the expression of CTGF protein by Western blot analysis in cultured mouse podocytes, which is one of the most important cell construction of glomerular filter barrier, and we also investigated the underlying ERK and Smads signaling pathway through which TGF beta(1) regulates CTGF expression. The levels of CTGF mRNA were assayed by RT-PCR.


RESULTS
Basal levels of CTGF protein were observed in cultured podocytes, treatment with 20 ng/ml PDGF and 10(-6) mol/L Ang. II for 24 h did not stimulate the expression of CTGF protein compared with control (P > 0.05), but significantly increase in levels of CTGF protein were seen in 1 ng/ml TGF beta(1) treated cells compared with with control (P < 0.05), and the levels of CTGF were up-regulated in a TGF beta(1) dose-dependent manner; The level of CTGF mRNA was also stimulated by 1 ng/ml TGF beta(1) at 12 h. 1 ng/ml TGF beta(1) induced phosphorylation of Smad(2) and ERK(1/2), and both reached the peak at 30 min; suppression of phosphorylation of Smad(2) with Staurosporine, a Serine/Threonine kinase inhibitor, diminished TGF beta(1)-triggered expression of CTGF protein, while blockade of phosphorylation of ERK(1/2) with PD98059, a specific ERK(1/2) activation inhibitor, did not decrease the TGF beta(1)-triggered expression of CTGF protein.


CONCLUSIONS
TGF beta(1) stimulated the expression of CTGF protein via Smad(2)-dependent and ERK(1/2)-independent signaling pathway in podocyte in vitro.
Huang
Hai-chang
HC
Department of Nephrology, Peking University First Hospital, Beijing 100034, China.
Liang
Yan
Y
Cheng
Li-jing
LJ
D000804:Angiotensin II / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor; D004268:DNA-Binding Proteins / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein; D015534:Trans-Activators / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
C526317:CCN2 protein, human; C526318:CCN2 protein, mouse; D004268:DNA-Binding Proteins; D005419:Flavonoids; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; C497782:SMAD2 protein, human; D051899:Smad2 Protein; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D000804:Angiotensin II; D055513:Connective Tissue Growth Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one