两种不同肝纤维化相关细胞因子shRNA重组质粒的构建

目的 构建以大鼠结缔组织生长因子(CTGF)和金属蛋白酶组织抑制因子1(TIMP-1)基因为靶点的短发夹RNA(shRNA)表达质粒.方法 根据前期筛选出的对CTGF和TIMP-1基因最有效的RNA干扰靶位,各设计一对有短发夹结构的RNA干扰(RNAi)靶点序列,退火形成双链DNA,克隆到质粒载体psiRNA-h7SK...     

RNA干扰TGF-β信号通路对人膀胱癌T24细胞迁移和侵袭能力的影响

目的 探讨过表达的TGF-β1和作用于TGF-β受体Ⅰ的干扰RNA(TsiRNA)在体外对人膀胱癌T24细胞迁移、侵袭能力的影响.方法 采用Transwell迁移试验、划痕试验以及Transwell侵袭实验观察过表达的TGF-β1和TsiRNA在体外对人膀胱癌T24细胞迁移、侵袭能力的影响,RT-PCR技术和蛋白免疫印迹法(Western blot)检测TGF-β1及TsiRNA处理后TGF-β受体Ⅰ基因与蛋白表达水平的变化.结果 过表达的TGF-β1可以显著提高膀胱癌T24细胞的迁移、侵袭能力,而TsiRNA可以完全降低由TGF-β1引起的T24的迁移、侵袭能力的变化.结论 膀胱癌细胞的迁移、侵袭能力与过表达的TGF-β1密切相关,TsiRNA可以降低T24细胞的迁移、侵袭能力.     

Targeting the tick protective antigen subolesin reduces vector infestations and pathogen infection by Anaplasma marginale and Babesia bigemina

The ultimate goal of vector vaccines is the control of vector infestations while reducing pathogen infection and transmission to protect against the many diseases caused by vector-borne pathogens. Previously (Vaccine 2011;29:2248-2254), we demonstrated that subolesin vaccination and release of tick larvae after subolesin knockdown by RNA interference (RNAi) were effective for the control of cattle tick, Rhipicephalus (Boophilus) microplus infestations in cattle. In this study, we used the fact that these animals were naturally infected with Anaplasma marginale and Babesia bigemina to evaluate the effect of subolesin vaccination and gene knockdown on tick infection by these cattle tick-transmitted pathogens. Ticks fed on vaccinated cattle had lower subolesin mRNA levels when compared to controls, resembling RNAi results. A. marginale and B. bigemina infection was determined by PCR and decreased by 98% and 99%, respectively in ticks fed on vaccinated cattle and by 97% and 99%, respectively after subolesin knockdown. These results demonstrated that targeting subolesin expression by vaccination or RNAi results in lower subolesin mRNA and pathogen infection levels, probably due to the effect of subolesin downregulation on tick feeding, gene expression and gut and salivary glands tissue development and function. These results suggested that subolesin vaccines could be used for the dual control of tick infestations and pathogen infection, a result that could be relevant for other vectors and vector-borne pathogens.     

vegf shRNA 对耐药白血病细胞化疗敏感性的增强作用

本研究采用RNA干扰技术探讨血管内皮生长因子(VEGF)对耐药白血病细胞K562/A02药物敏感性的影响及其机制。针对人vegf基因合成3个特异性shRNA干扰片段,采用脂质体介导的方法将其导入K562/A02细胞,用RT-PCR检测vegf及mrp1的mRNA表达水平,用Western blot检测VEGF、MRP1、AKT及P-AKT的蛋白表达情况,用MTT法检测阿霉素对各组细胞的半数抑制浓度(IC50),用流式细胞术检测细胞凋亡、胞内罗丹明123(Rho123)积聚情况。结果表明:转染vegf shRNA后,K562/A02细胞vegf的mRNA表达下调,其中vegf shRNA2组和vegf shRNA3组与HK组比较有显著差异(p<0.05),以vegf shRNA3组最显著,VEGF蛋白表达也出现下调,与mRNA的表达基本一致;MTT检测结果显示阳性转染组对阿霉素的敏感性增加,其中vegf shRNA2组和vegfshRNA3组的半数抑制浓度(IC50)与HK组比较具有显著的统计学差异(p<0.05);阳性转染组胞内Rho123积聚增多,与HK组比较均有统计学差异(p<0.05);阳性转染组细胞凋...     

Thermodynamic stability of small hairpin RNAs highly influences the loading process of different mammalian Argonautes

MicroRNAs and siRNAs interact with target sequences in mRNAs, inducing cleavage- and non-cleavage-based gene repression through the RNA-induced silencing complex (RISC) that consists of one of four mammalian Argonaute proteins, Ago1-Ago4. The process of how Dicer substrate small hairpin RNAs (shRNAs) are loaded into different mammalian Agos in vivo is not well established. Here we report that shRNAs are loaded into mammalian Agos in two stepwise processes, physical association and activation, with the latter being the rate-limiting step with noncleaving RISC. We establish that, although RNA duplexes processed from shRNAs bind to Agos in cells with similar affinity, the degree by which the complexes are activated (coupled with the removal of the passenger strand) correlates with the thermodynamic instability of RNA duplexes being loaded rather than the structure of the RNA, as was previously demonstrated in Drosophila. Interestingly, Ago loading of siRNAs is less sensitive to thermostability than that of their shRNA equivalents. These results may have important implications for the future design of RNAi-based therapeutics.     

心脏钠通道无义突变的分子拯救部分恢复钠通道的表达和功能

目的 研究探讨真核释放因子eRF3a的RNA干扰如何影响心脏钠通道无义突变的表达和功能.方法 构建心脏钠通道无义突变和干扰eRF3a RNA的真核表达载体,独立或共同转染HEK293细胞,全细胞膜片钳记录钠通道的表达电流和动力学,同时应用蛋白印迹和免疫荧光证明钠通道的表达和定位.结果 独立转染W822X无义突变的HEK293细胞没有检测到全长钠通道蛋白,表达的钠电流水平很低,仅相当野生型钠电流3%.共同转染HEK293细胞可以检测到全长钠通道蛋白,表达的钠电流水平明显增加,相当于野生型钠电流30%.免疫荧光也显示,独立转染W822X无义突变的HEK293细胞没有出现荧光细胞,而共同转染的HEK293细胞出现较多的荧光细胞.结论 真核释放因子eRF3a的RNA干扰促进心脏钠通道无义突变的翻译,部分恢复钠通道全长表达和功能.

Abstract：

Objective In this study we investigated the functional restoration of nonsense mutations in the SCN5A gene. Methods The readthrough-enhancing reagents were introduced to HEK293 cells to suppress one nonsense mutation W822X in the SCN5A gene. Patch-clamp was used to record the whole-cell current and dynamics. Western blot and immunofluorescence staining were used to certify the expression and the location of the sodium channel. Results In transfected HEK293 cells, the nonsense mutation in SCN5A inhibited the expression level of full-length protein, and the sodium currents from the mutant channels were less than 3% of the wild-type level. Readthrough enhancement by decreasing translation termination efficiency with a siRNA targeting eukaryotic release factor eRF3a ( a GTPase that binds eRF1 ), the sodium current from the mutant cDNAs was restored to as much as 30% of the wild-type. After the treatment by the readthrough-enhancing reagents, the channels from cDNA carrying W822X remained the features of wild-type phenotype, and Western blot and immunochemical staining also showed the expression of full-length channel proteins. Conclusion Readthrough-enhancing reagents could effectively suppress nonsense mutations in SCN5A and partially restore the function of sodium channel and the expression of full-length channels.     

Interference by clustered regularly interspaced short palindromic repeat (CRISPR) RNA is governed by a seed sequence

Prokaryotic clustered regularly interspaced short palindromic repeat (CRISPR)/Cas (CRISPR-associated sequences) systems provide adaptive immunity against viruses when a spacer sequence of small CRISPR RNA (crRNA) matches a protospacer sequence in the viral genome. Viruses that escape CRISPR/Cas resistance carry point mutations in protospacers, though not all protospacer mutations lead to escape. Here, we show that in the case of Escherichia coli subtype CRISPR/Cas system, the requirements for crRNA matching are strict only for a seven-nucleotide seed region of a protospacer immediately following the essential protospacer-adjacent motif. Mutations in the seed region abolish CRISPR/Cas mediated immunity by reducing the binding affinity of the crRNA-guided Cascade complex to protospacer DNA. We propose that the crRNA seed sequence plays a role in the initial scanning of invader DNA for a match, before base pairing of the full-length spacer occurs, which may enhance the protospacer locating efficiency of the E. coli Cascade complex. In agreement with this proposal, single or multiple mutations within the protospacer but outside the seed region do not lead to escape. The relaxed specificity of the CRISPR/Cas system limits escape possibilities and allows a single crRNA to effectively target numerous related viruses.