| Introduction Both in vitro and in vivo studies show that transforming growth factor-β(TGF-β) plays a pivotal role in the progression of glomerulosclerosis. It is proved that TGF-β can stimulate the synthesis of glomerular ECM in parallel with the down-regulation of matrix metalloproteinases, and the up-regulation of matrix metalloproteinase inhibitors in mesangial cells(MsC). Recent studies have identified that TGF-β signals were transmitted through a heteromeric receptor complex of two distinct type Ⅰand typeⅡ serine/threonine kinase receptors, TβRⅠand TβRⅡ. The activated TβRⅠthen directly transmits signal to downstream intracellular substrates , restricted Smads(Smad2,3). Then the phosphorylated Smad2,3 hetero oligomer with Smad4 in cytoplasm, translocated into the nucleolus ,binding with sequence-specific DNA-binding proteins, resulting in the positive or negative regulation of ligand-responsive genes. Recently, a number of possible methods, including adenovirus vector carrying Smad7 cDNA and ultrasound-microbubble-mediated system carrying doxycycline-regulated Smad7 cDNA which can enhance Smad7 over-expression, to antagonise renal interstitial fibrosis . Lately, more and more studies show that IFN-γ has antifibrosis function, which involves inhibition of cell proliferation and ECM synthesis. The mechanism may be correlated with enhancing Smad7 expression. In this study , we first explore ex vivo gene transfer technique and IFN-γstimulation, which can upregulate Smad7 expression to investigate the changes of MMP-2/TIMP-2 , uPA/PAI-1 expression on MsC and ECM synthesis both in vitro and in vivo in order to provide valuable clues for searching and developing new approaches to prevention and treatment of glomerulosclerosis .Part ⅠThe changes of MMP-2/TIMP-2 and uPA/PAI-1 expression on cultured rat mesangial cells transfected with Smad7 vector Objectives To elucidate the mechanism of Smad7 blocking tissue fibrosis by observing MMP-2/TIMP-2 and uPA/PAI-1 expression on the cultured rat MsC transfected with Smad7 vector. Methods Lipofectin method was used to transfect Smad7 vector into MsC, Northern blot and Western blot analysis for detecting Smad7 protein and mRNA expression level. The expression of MMP-2/TIMP-2 and uPA/PAI-1 were determined by Northern blot , Western blot and zymography assay ,respectively. Results Over-expresion Smad7 on positive two MsC clones (S-22,S-26) were successfully established . Two MsC clones showed increased expression of MMP-2 / uPA protein , about 3.8 and 2.5 mutiples respectively compared to the control group, however the expression of TIMP-2 / PAI-1 protein were suppressed, down about 48% and 45% respectively compared to the control group.Conclusions It is possible that Smad7 can alleviate the development of tissue fibrosis by upregulating the expression of MMP-2/ uPA and downregulating the expressions of TIMP-2/ PAI-1.PartⅡ Preliminary observation on the changes of Smad7 and collagen expression in rat MsC and diseased renal tissueObjectives To elucidate the antifibrosis mechanism of IFN-γ in order to provide valuable clues for searching and developing new approaches to the prevention and treatment of organ fibrosis .Methods Northern blot and Western blot were used to detect the expression of Smad7 ,Col Ⅰand Col Ⅳ in MsC, when mesangial cells were treated with 10ng/μl IFN-γ for 1,6,12,24 and 48h.ATS nephritis rat models were injected IFN-γ(150×103IU/kg) by tail vein,then Northern blot, Western blot and immunohistochemistry were used to detect the expression of Smad7 and Col Ⅳ in diseased renal tissue.Results IFN-γcould increase the expression of Smad7 protin,about 2.2 mutiples compared to the control group, and decrease the expression of Col Ⅰ, Col Ⅳproteins, down about 50% and 48% respectively compared to the control group. Administration IFN-γ can alleviate Col Ⅳ aggradation in the tissue of ATS glomerulonephritis, Col Ⅳ mRNA expression decreased about 75% compared to the control group. Conclusion...
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