Effects of Smad4 on liver fibrosis and hepatocarcinogenesis in mice treated with CCl4/ethanol / 中华肝脏病杂志

To study the effects of Smad4 on liver fibrosis and hepatocarcinogenesis in mice treated with CCl(4)/ethanol. The wild-type mice (Smad4 +/+) and the Smad4 knockout mice (Smad4 +/-) were injected subcutaneously with carbon tetrachloride(CCl(4))/ethanol twice a week for twenty weeks. The expression of Smad4, TGFbeta1, Smad2, Smad3, Smad6, TIMP1, MMP2 and MMP9 was detected by RT-PCR. In the cirrhotic liver, the expression of Smad4 mRNA was significantly higher than that in the normal liver. Comparing with wild-type mice (Smad4 +/+), the TGFbeta1-Smad4 signaling was markedly attenuated in the Smad4 knockout mice (Smad4 +/-). After induction by CCl(4)/ethanol, the hepatic fibrosis in the Smad4 knockout mice (Smad4 +/-) was obviously alleviated compared with the wild-type mice (Smad4 +/+), and the incidence rate of hepatocarcinogenesis of the former was also lower than that of the latter(32.0% vs 41.9%). These results indicate that knocking out Smad4 can delay the progression of liver fibrosis and liver cancer.

Study on the Expression, Purification and Activity of Arginine Deiminase / 中国生物工程杂志

Objective: To develop a high efficient expression, purification system of recombinant arginine deiminase(ADI).Methods: cDNA fragment encoding for mycoplasma ADI was obtained by artificial synthesis and was cloned into prokaryotic expression vector(pBV220). The recombinant ADI was generated by the transformation of the recombinant vector into the host strain DH5?. Anion exchange and gel filtration chromatography was carried out for purification of the recombinant ADI. The biological activity of final product was detected by the assay of agrinine degradation in vitro. Results: A prokaryotic expression plasmid pBV220-ADI was generated successfully, and was identified by DNA sequencing; the recombinant protein was highly expressed in DH5?, the proportion of the recombinant protein is exceeded 35% of the whole protein. The inclusion bodies were solubilized with 6mol/L guanidine hydrochloride under reducing conditions in order to avoid incorrect disulfide-bond formation of the recombinant ADI molecules. Dilution and dialysis at lower degrees temperature were the optimum renaturation methods. After gel filtration, the purity and specific activity of rADI reached 95% and 80 IU/mg respectively. Conclusions: A set of protocols for high efficient rADI expression and purification has been established, which is simple, efficient and applicable.

Effects of portaazygous disconnection, portocaval shunt and selective shunts on experimental rat liver cirrhosis / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To evaluate the effects of portaazygous disconnection (PAD), portacaval shunt (PCS) and distal splenocaval shunt (DSCS) on the portosytemic shunting (PSS), hepatic function (HF), hepatic mitochondrial respiratory function (HMRF), oral glucose tolerance test (OGTT) and arterial ketone body ratio (KBR) in order to provide a sound basis for selecting suitable operations for patients.</p><p><b>METHODS</b>Using a cirrhotic portal hypertensive model induced by CCl4/ethanol in Wistar rats, the PSS, HF, HMRF, OGTT and KBR were determined three weeks after PCS, DSCS and PAD.</p><p><b>RESULTS</b>It was revealed that: (1) In the cirrhotic portal hypertension rats, the PSS increased significantly, HMRF and hepatic reserve function (HRF) decreased significantly when compared with the control rats. (2) At the time of first postoperative week, the mean blood glucose value in the 120-minute OGTT in each PAD, PCS and DSCS groups had significant differences compared with the cirrhotic control group. But during the second and third postoperative weeks, the mean blood glucose values in the 120-minute OGTT in both PAD and DSCS groups had no significant differences compared with the cirrhotic control group except for the PCS group. The values of KBR in the three operative groups decreased significantly compared with the cirrhotic control group during the two postoperative weeks. In the third postoperative week, only the values of KBR in the PCS group had a significant difference compared with the cirrhotic control group. (3) After PCS, the PSS was further increased; HF and HMRF were significantly decreased. Little improvement was found in the third postoperative week. (4) After DSCS and PAD, the above mentioned indices were less influenced, and they were restored more quickly than those in the PCS group.</p><p><b>CONCLUSION</b>We found that PAD and DSCS are more desirable than PCS.</p>

Inhibitory effect of retroviral vector containing anti-sense Smad4 gene on Ito cell line, LI90 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Transforming growth factor-beta1 (TGF-beta1) exerts strong fibrogenic potential in culture-activated HSCs. Smad4 is a key intracellular mediator for the transforming growth factor-beta (TGF-beta) superfamily of growth factors. The aim of this study was to assess the effects of the antisense Smad4 gene on Ito cell line, LI90.</p><p><b>METHODS</b>The recombinant retroviral vector pLXSN-Smad4 was constructed by cloning the rat antisense Smad4 cDNA into the retroviral vector pLXSN. Retroviruses with or without the antisense gene were obtained by transfecting pLXSN-Smad4 and pLXSN vectors into PA317 cells. Human hepatic stellate cells (HSCs) LI90 were infected with these retroviruses followed by selection with G418. The expression of Smad4 was detected by Northern and Western blots. Cell biological characteristics, including cell growth curve, 3H-TdR and 3H-proline uptake by HSCs and the production of extracellular matrix were assessed.</p><p><b>RESULTS</b>mRNA and protein expressions of Smad4 in LI90 cells transfected with retrovirus containing the antisense Smad4 gene were much lower than those in LI90 cells transfected with empty vector or parental LI90 cells. Cells hypoexpressing the Smad4 gene exhibited a slower rate of growth, a lower uptake of 3H-TdR and 3H-proline (P < 0.01), and smaller production of th extracellular matrix, compared with parental LI90 cells and cells transfected with empty retrovirus.</p><p><b>CONCLUSIONS</b>The antisense Smad4 gene can suppress the expression of the Smad4 gene, reduce endogenous production of Smad4 mRNA and protein, block TGF-beta1 signaling pathway, inhibit activation of Ito cells, obstruct the growth of Ito cells, decrease the production of the extracellular matrix (ECM). Our results may provide a basis for the development of antifibrotic gene therapy.</p>

Obstruction of TGF-beta1 signal transduction by anti-Smad4 gene can therapy experimental liver fibrosis in the rat / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To study the therapeutic effects to block the TGF-beta1 (transforming growth factor beta1) signal transduction by antisense Smad4 gene on experimental fibrotic liver.</p><p><b>METHODS</b>Using the rat model of liver fibrosis induced by Carbon Tetrachloride (CCl4)/ethanol, we transfected antisense Smad4 gene mediated by adenovirus via portal vein infusion into the liver, and observed the expression of Smad4 by Retro-Polymerase Chain Reaction (RT-PCR) and Western Blot. We also investigated the pathologic features and collagen expression.</p><p><b>RESULTS</b>In the non-therapeutic cirrhotic liver, the expression of Smad4 mRNA was significantly increased than normal liver, and so was the collagen I. After antisense Smad4 gene being transfected, the expression of Smad4 mRNA and that of collagen I in the therapeutic liver was significantly decreased, compared with the non-therapeutic cirrhotic liver. The fibrous degree of therapeutic liver was also reduced compared with the non-therapeutic fibrous liver.</p><p><b>CONCLUSION</b>These results indicate that because antisense Smad4 gene could block TGF-beta1 signal transduction by reducing the expression of Smad4, so it could inhibit the production of extracellular matrix (ECM) and improve hepatic fibrosis.</p>