Summary
Background
Keloids represent a dysregulated response to cutaneous wounding that result in an
excessive deposition of extracellular matrix (ECM), especially types I and III collagen.
In keloid scars, the ratio of ‘type I to type III collagen’ varies compared to normal
skin. Transforming growth factor β (TGF-β) plays a central role in the pathogenesis
of fibrosis by inducing and sustaining activation of keloid fibroblasts. However,
the underlying mechanisms are poorly understood. RNA interference (RNAi) is an evolutionally
conserved mechanism for repressing targeted gene expression. In mammalian cells, RNAi
is mediated by small interfering RNA (siRNA). In this paper, we examined the function
of Sma and Drosophila mothers against decapentaplegic homolog 3 (Smad3), recently characterized as intracellular
effector of TGF-β signalling, in keloid fibroblasts using siRNA.
Methods
Dermal fibroblasts obtained from one female patient aged 21 years were maintained
in Dulbecco's modified Eagle's medium. Cells (<6 passages) were treated with or without
Smad3 siRNA and the expression levels of related genes were examined by Reverse Transcription
Polymerase Chain Reaction (RT-PCR) and Western Blot. Statistical analysis was performed
using one-way ANOVA (Dunnett correction) and the Excel 7.0 software, with significance
set at p<0.05.
Results
The knockdown of Smad3 expression in mRNA and protein levels was confirmed using RT-PCR
and Western Blot. Compared to blank, the mRNA levels of types I and III procollagen
were also significantly and uniquely decreased following the reduction of Smad3 by
siRNA (p<0.05).
The results indicate that Smad3 plays an important role in the TGF-β induced fibrosis
in keloid. Downregulation of Smad3 expression in keloid fibroblasts can significantly
decrease procollagen gene expression. SiRNA targeting Smad3 was an efficient reagent
to reduce ECM deposition and attenuate process of fibrosis. It could be a new promising
therapeutic approach to improve skin wound healing and inhibit progression of fibrotic
conditions by interrupting the TGF-β signal pathway.
Keywords
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Article info
Publication history
Published online: January 22, 2007
Accepted:
May 9,
2006
Received:
November 19,
2005
Footnotes
☆Zimin Wang, Zhongyu Gao and Yi Shi contribute equally to this paper.
Identification
Copyright
© 2006 Published by Elsevier Inc.
