Emerging relationship between RNA helicases and autophagy / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

RNA helicases, the largest family of proteins that participate in RNA metabolism, stabilize the intracellular environment through various processes, such as translation and pre-RNA splicing. These proteins are also involved in some diseases, such as cancers and viral diseases. Autophagy, a self-digestive and cytoprotective trafficking process in which superfluous organelles and cellular garbage are degraded to stabilize the internal environment or maintain basic cellular survival, is associated with human diseases. Interestingly, similar to autophagy, RNA helicases play important roles in maintaining cellular homeostasis and are related to many types of diseases. According to recent studies, RNA helicases are closely related to autophagy, participate in regulating autophagy, or serve as a bridge between autophagy and other cellular activities that widely regulate some pathophysiological processes or the development and progression of diseases. Here, we summarize the most recent studies to understand how RNA helicases function as regulatory proteins and determine their association with autophagy in various diseases.

Construction of heparanase gene-targeted small interfering RNA and its gene silencing effect / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct heparanase gene-targeted small interfering RNA(siRNA) and its expression vector and to observe its interference effect on the expression of heparanase gene in human malignant melanoma A375 cell.</p><p><b>METHODS</b>Heparanase gene-targeted hairpin siRNA was designed, two complementary oligonucleotide strand was synthesized and inserted into pRNATU6.1 vector, which was then identified by PCR and sequencing. Human malignant melanoma A375 cells were transfected with the constructed vector using lipofectamine method. Semi-quantitative PCR was performed to evaluate the heparanase-mRNA expression levels, and Western blot was performed to evaluate the expression of heparanase protein.</p><p><b>RESULTS</b>The vector containing siRNA was identified by PCR and sequencing; the results of semi-quantitative PCR and Western blot showed that the expression levels of both heparanase RNA and protein in transfected A375 cells were decreased significantly(P<0.05).</p><p><b>CONCLUSION</b>The heparanase gene-targeted siRNA and its vector were successfully constructed, which can reduce the heparanase gene and protein expression in transfected cells.</p>

Mutations of the tumor suppressor Kruppel-like factor 6 (KLF6) gene in hepatocellular carcinoma and its effect of growth suppression on human hepatocellular carcinoma cell line HepG2 / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To explore the mutated KLF6 gene in hepatocellular carcinoma (HCC) and to characterize its behavior in human hepatocellular carcinoma cell line HepG2.</p><p><b>METHODS</b>We analyzed the DNA isolated from 23 hepatocellular carcinoma tissues and their adjacent nontumor tissues by polymerase chain reaction (PCR). Direct sequencing was used to establish the incidence of mutation in exon2 of the KLF6 gene. Loss of growth suppressive function of the HCC-derived KLF6 mutants was characterized by in vitro analyzing alteration of cell cycle and MTT assay. Expression of p21WAF1, a possible downstream gene of KLF6, was detected in human hepatocellular carcinoma cell line HepG2 transiently transfected with KLF6 genes.</p><p><b>RESULTS</b>Mutations of KLF6 were found in 2 of the 23 (8.7%) hepatocellular carcinomas. The two mutations were located in the transactivation domain and one of them resulted in single amino acid substitution of TGG (W) by GGG (G) at codon 162. Unlike the wild-type KLF6, cancer-derived KLF6 mutants neither suppressed growth nor induced p21WAF1 following transfection into culture cells.</p><p><b>CONCLUSIONS</b>Mutations of the KLF6 gene may play a role in the pathogenesis of HCC, but are not the dominating mechanism resulting in inactivation of KLF6 functions. KLF6 suppresses hepatocellular carcinoma cell proliferation partly through upregulating expression of the p21WAF1 gene.</p>

Application of PCR-based tRNAval Pol III-shRNA expression cassettes in screening of efficient siRNA for inhibiting hepatitis B virus / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To screen efficient siRNA for inhibiting hepatitis B virus using the technique of PCR-based tRNA(val) Pol III-shRNA expression cassettes (SECs).</p><p><b>METHODS</b>Based on core gene sequence of HBV, five target sites of siRNA were designed. tRNAval Pol III-shRNA expression cassettes produced by one-step overlapping extension PCR strategy were co-transfected with HBV C gene and pC-EGFP plasmid into AD293 cells respectively. Forty-eight hours after transfection, fluorescence of HBVC-GFP protein was detected by fluorescence-activated cell sorting (FACS); HBV C mRNA was detected by semi-quantitative RT-PCR. HBV-producing HepG2. 2. 15 cells were transfected with selected SECs for 72 h, HBsAg and HBeAg in the cell culture medium were detected by radioimmunoassay assay (RIA). HBV pgRNA from cell total RNA was detected by semi-quantitative PCR.</p><p><b>RESULT</b>Co-transfection with pC-GFP plasmid and SECs into AD293 cells resulted in inhibition expression of HBV C gene and decrease of EGFP fluorescence intensity. SEC-492i showed most significant inhibition effect on HBV C-EGFP expression compared with other SECs. Selected SEC-492i or SEC-282i targeting core gene could efficiently decrease expression of HBeAg and the level of HBV pgRNA in a dose-dependent manner. SEC-492i inhibited HBV replication and antigen expression in a more efficient way than SEC-282i at the same final concentration.</p><p><b>CONCLUSION</b>The expressed shRNA, which targets sites on HBV C mRNA in 492i, is to have having most efficient RNAi effect. tRNAval Pol III-shRNA expression cassettes produced by one-step overlapping extension PCR strategy should be useful for identification of optimal siRNA.</p>

Inhibition of HBV core antigen gene expression in human embryonic kidney cell line AD293 by plasmid-based RNAi / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To inhibit HBV core antigen gene expression with plasmid-based RNAi.</p><p><b>METHODS</b>The shRNA expression vector targeting HBV core antigen gene was designed and constructed. Human embryonic kidney cell line AD293 was co-transfected with HBcAg-EGFP fusion protein expression vector and shRNA expression vector transiently, and the cells without shRNA-transfection and with non-specific shRNA transfection were used as controls. Inhibitory effect of RNAi was detected by fluorescence-activated cell sorting (FACS) and real-time fluorescence quantificational RT-PCR.</p><p><b>RESULTS</b>HBV core antigen gene expression in AD293 was inhibited by shRNA, with the maximal inhibition rate of 76 % measured by FACS and of 63.1 % by real-time PCR.</p><p><b>CONCLUSION</b>Effective inhibition of HBV core antigen gene expression by plasmid-based RNAi provides an alternative for anti-HBV study in vitro, which has potential clinical application.</p>

Inhibition of HBs-GFP fusion gene expression by RNA interference / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To develop an effective report gene system to test the effect of small interfering RNA (siRNA).</p><p><b>METHODS</b>HBV S gene was fused with enhanced green fluorescent protein (EGFP) gene to form HBs-GFP and the plasmid containing HBs-GFP was constructed. A vector expressing small hairpin RNA (shRNA) pAVU6 + 4sh357 was also constructed. Two plasmids were co-transfected into HepG2 cells transiently. The fluorescence of HBs-GFP was detected by fluorescence-activated cell sorting (FACS). The mRNA expression in HepG2 cells was detected by conventional RT-PCR and real-time PCR.</p><p><b>RESULTS</b>siRNA inhibited the expression of HBs-GFP 72 hours post transfection. The fluorescence of HBs-GFP in HepG2 cells treated with pAVU6+4sh357 was reduced by 55.4% compared with that of controls. The HBs-GFP expression in HepG2 cells treated with pAVU6+4sh357 was reduced by 76.3% and 90% as measured with conventional RT-PCR and real-time PCR, respectively.</p><p><b>CONCLUSION</b>This investigation demonstrated siRNA derived from shRNA expression vectors can inhibit the expression of HBs-GFP in HepG2 cells.</p>

Combination of lamivudine with thymosin alpha1 in treatment of duck hepatitis B / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To explore the inhibitory effect of combination of lamivudine with thymosin alpha1 (Talpha1) on the replication of duck hepatitis B virus (DHBV).</p><p><b>METHODS</b>Peking ducks of 1 d old were challenged with DHBV-positive serum and used as a duck hepatitis B model. After treated with lamivudine for three months, the ducks were randomly grouped and treated with or without Talpha1 for 8 d. Serum DHBV titrate was observed by semi-quantitative PCR, and inflammation and degeneration of hepatocytes were observed by pathology examination.</p><p><b>RESULTS</b>The serum DHBV titrate was significantly reduced (4483.2+/-5193.4 compared with 9351.8+/-5059.6) after lamivudine treatment, and it was reduced more significantly(1692.2+/-589.2) after combination treatment with Talpha1. Lamivudine reduced the degeneration degree of hepatocytes (3.2+/-0.8 compared with 4.6+/-0.5) and the inflammation degree of liver (6.2+/-3.3 compared with 8.6+/-2.8). The combination treatment with Talpha1 increased liver inflammation degree (9.0+/-5.2).</p><p><b>CONCLUSION</b>Both Talpha1 and lamivudine may reduce the replication of DHBV in Peking ducks and combination treatment may have the better anti-virus effect and enhance immune response in liver.</p>

Development of a system for quick screening of efficient HBx-siRNA / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To develop a system for quick screening of efficient siRNA targeted HBx mRNA.</p><p><b>METHODS</b>Using recombination DNA technique, the fusion expression plasmid of HBx and EGFP was constructed, and siRNA expression cassettes (SECs) containing U6+1, H1 or tRNA(Val )promoter were prepared via one-step overlapping extension PCR. By co-transfection with recombinant plasmid and SECs into AD293 cell, the inhibition effects on the transient expression of HBx-EGFP fusion protein were analyzed by FACS and semi-quantitated RT-PCR analysis.</p><p><b>RESULT</b>(1)HBx-EGFP fusion protein expression plasmid pHBx-EGFP was constructed successfully, which expressed green fluorescence in cell mainly located at plasma or the periphery of nucleus in granules. (2) Co-transfection with recombinant plasmid and SECs into AD293 cells resulted in inhibition of HBx-EGFP expression. SEC-siHBx388 showed significant inhibition effect on HBx-EGFP expression compared with SEC-siHBx271, indicating that siHBx388 is effective siRNA site and could be screened out with our screening system. In addition,the results of that U6+1-, tRNA(Val) and H1-siHBx388 reduced HBx-EGFP expression by 21.7%, 12.9% and 12.4% of control respectively indicated that both tRNAVal and H1 promoter was high efficient in driving effect of siHBx388.</p><p><b>CONCLUSION</b>Combination of the HBx expression carrying reporter gene and PCR-based multi promoter SECs may develop a useful system to be applied in identification of optimal HBx- siRNA and its matching promoter.</p>

Establish a screening system for selection of mRNA target sites for HBsAg to construct siRNA with shRNA / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To find some effective short interfering RNA's sites targeting HBV surface gene sequence using shRNA expression vectors.</p><p><b>METHODS</b>Four shRNA expression vectors targeting HBV surface gene sequence were constructed based on pAVU6 + 27 vector, and cotransfected into AD293 cells with HBs-EGFP fusion gene plasmid. The changes of HBs-EGFP image were detected by FACS and microscopy. The HBs-EGFP mRNA expression was evaluated by RT-PCR.</p><p><b>RESULTS</b>Four shRNA expression vectors and HBs-EGFP fusion gene plasmid were successfully constructed. pAVU6 + 4sh579 vector inhibited the HBs-EGFP expression by 69.8% in AD293 and suppressed the HBs-EGFP mRNA expression by 74.6%.</p><p><b>CONCLUSIONS</b>The results showed that the 579 site of HBV surface gene sequence was an effective target and pAVU6 + 4sh579 vector could suppress the HBs-EGFP expression in AD293 cells</p>

Construction of small interfering RNA targeting heparanase gene and its inhibitory effect on the in-vasiveness of human malignant melanoma cell line A375 in vitro / 中华皮肤科杂志

Objective To construct the small interfering RNA (siRNA) targeting heparanase gene and its expressing vector,and to observe its interference effect on the expression of heparanase gene and inhibitory effect on the invasive potential of human malignant melanoma A375 cells.Methods Three siRNAs were designed.The recombinant plasmid pRNATU6.1/heparanase-siRNA was designed and constructed. A375 cells were cultured,and transfected with pRNATU6.1/heparanase-siRNA.The cells treated with lipo- fectamine or Opti-MEM served as the controls.Real-time fluorescence quantitative PCR and Western blot were performed to evaluate the expression of heparanase RNA and protein in these treated A375 cells.The in vitro invasive potential of treated A375 cells was assessed by Matrigel gel assay.Results The siRNA targeting heparanase gene was successfully cloned to the eukaryotic expressing vector pRNATU6.1.The expression levels of both heparanase RNA and protein decreased significantly in siRNA-transfected A375 cells than those in the control cells.The in vitro invasive potential of siRNA-transfected cells was also signifi- cantly inhibited as compared with that of the control cells (P