[Role of Smad signaling in transcription of Smad7 gene mediated by TGF-beta1 in odontoblast cell line MDPC-23].
OBJECTIVE
To investigate the role of Smad signaling in transcription of Smad7 gene mediated by TGF-beta1 in odontoblast cell line MDPC-23, and to explore the molecular mechanism of Smad7 gene expression mediated by TGF-beta1 at the transcriptional level.


METHODS
Smad function and its role in transcription of Smad7 were investigated in cotransfection experiments using Smad7 promoter-luciferase reporter construct containing the sequence between -408 bp and +112 bp of mouse Smad7 gene. The data were analysed by one-way ANOVA.


RESULTS
When the Smad7 promoter-luciferase reporter gene construct was expressed in MDPC-23 cells, its transcriptional activity was significantly induced by TGF-beta1 treatment, whereas not by BMP-2 treatment. Overexpression of Smad1, 2, 4, or 5 had no effect on transcriptional activity of Smad7 promoter. Overexpression of Smad3 markedly promoted transcriptional activity of Smad7 promoter, whereas co-transfection of Smad3 and Smad4 doubled the effect of Smad3. Overexpression of Smad3 dominant negative mutant or Smad3 antisense cDNA (AS-Smad3) significantly inhibited transcriptional activity of Smad7 promoter induced by TGF-beta1.


CONCLUSIONS
TGF-beta1 regulated transcription of Smad7 gene through association of Smad3 and Smad4 in MDPC-23 cells.
He
Wen-xi
WX
Department of Conservative Dentistry, College of Stomatology, The Fourth Military Medical University, Xi'an 710032, China. hwenxi@yahoo.com.cn
Niu
Zhong-ying
ZY
Zhao
Shou-liang
SL
Zang
Xiao-xia
XX
Gao
Jie
J
Li
Ping
P
D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins; D051379:Mice; D009804:Odontoblasts / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D051906:Smad7 Protein / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
D004268:DNA-Binding Proteins; D051906:Smad7 Protein; D015534:Trans-Activators; D053773:Transforming Growth Factor beta1