The Anti-hepatic Fibrogenesis Of Smad3/siRNA Through Blocking TGF-β/Smad3 Signaling Pathway

The multiple biological actions of TGF-81 contribute to the regulation of the production, degradation, and accumulation of ECM proteins in a direct or indirect manner, and that it may play a pivotal role in the fibroproliferative changes in many vital organs and tissue. Activation of hepatic stellate cells (HSCs), leading to accumulation of extracellular matrix (ECM), is the central event of fibrogenesis. liver fibrosis occurs as a consequence of the transdifferentiation of HSCs into myofibroblasts and is orcharded by TGF-β/Smad3 signaling pathway. There are a number of reports of cellular or animal models of fibrosis where loss of TGF-β1/Smad3 cascade regulation results in a diminished fibrotic response where agents that block TGF-βfunction inhibit the production of ECM and reduce the fibrotic response in the liver and other tissues. Several strategies now exist for preventing or halting fibrogenesis, ranging from biological agents including antibodies, antisense oligonucleotides, soluble type II TGF-βreceptor and siRNA to small molecular compounds. However, it has not reported that an agent blocks TGF-β/Smad3 signaling cascade through targeting Smad3 protein.The luciferase reporter based on TGF-β/Smad3 signaling was developed, whose expression was inhibited by SB-431542, a small molecular inhibitor of type I TGF-βreceptor. A stable MvlLu strain cloned the reporter system was worked.Naringenin, a Chinese herbs extract, was firstly proven to be an antagonist of TGF-β/Smad3 signaling, which obviously inhibited the expression of the luciferase reporter. The compound could interdict not only the formation of ECM, but the transcription of Smad3 in HSCs induced by TGF-B1 in vitro. We firstly provided obvious evidences that naringenin can intervene TGF-β1/Smad3 signaling pathway by directly or indirectly down-regulated Smad3 protein expression to exert anti-fibrogenic effects, at least partly.But the most compellent example of events is that loss of Smad3, a downstream mediator of TGF-β1 signaling, might be resistant to fibrogenesis in vivo and in vitro. Based on these and other advances in understanding the fundamentals of the injury response and TGF-β1/Smad3 signal pathway, a strategy which blocks TGF-B signaling via silencing Smad3 gene with small interference RNA (siRNA) was developed. A siRNA/Smad3 could intervene the TGF-β1/Smad3 signaling, which was shown by the luciferase reporter system, and knockdown Smad3 gene in a dose-dependent manner from RT-PCR results. The siRNA could inhibit the expression of ECM at levels of mRNA and protein in HSCs induced by TGF-β1. The siRNA/Smad3 could survive, increase body weigh and liver weigh, decrease the serum levels of TGF-β1 and the components of serum ECM, improve the liver biological functions, and reduce the liver contents of ECM components in experimental liver fibrotic rats induced by DMN. These results implied that siRNA targeting Smad3 has exciting anti-fibrogenesis actions and future studies will be required to determine the approach is most beneficial.