miRNA和siRNA.ppt

Review GGPPS 肝癌 PPAR-γ 脂肪肝 EGR-1 肝纤维化 PP2A 肝再生 参考文献：》30篇 格式:世界华人消化杂志 中文文献不超过30% 12月27日递交 纸制\电子版 The discovery of miRNAs The first discoered miRNA: lin-4 Breakthrough with BlastN of the second miRNA (stRNA) let-7 Three strategies of miRNA and target recognition (targets are locating in 3’ UTRs). Create induced phenotypes that can be observed over long time spans Create a stably engineered cells can be assayed either in vitro or in vivo, perhaps testing the angiogenic or metastatic potentials of tumor cells in xenograft models。 Create hypomorphic alleles rapidly in transgenic mice. 4. Combine shRNAs with existing high-efficiency gene delivery vehicles to create bona fide RNAi-based therapeutics. For example, ultimately, to silence a disease-causing mutant allele specifically. Research Applications of RNAi: A new strategy of reverse genetics a novel way of gene knock-out It can be used in reverse genetics to identify the cellular or biological function of a gene. It can be combined with genomics to perform large-scale genetic screens aimed at gene discovery. Therapeutic Applications of RNAi:A new strategy to invitation of new drugs and gene therapy siRNAs can be used to counter viral infection by specifically destroying the mRNAs of the pathogenic viruses, such as HIV and HBV. siRNAs can be applied to counter cancers by specifically down-regulate the expression of genes related to oncogenesis. miRNA与siRNA之间有许多相同之处：1.二者的长度都约在22nt左右。2.二者都依赖Dicer酶的加工，是Dicer的产物，所以具有Dicer产物的特点。3.二者生成都需要Argonaute家族蛋白存在。4.二者都是RISC组分，所以其功能界限变得不清晰，如二者在介导沉默机制上有重叠。5.miRNA和siRNA合成都是由双链的RNA或RNA前体形成的。miRNA与siRNA的不同点：1.根本区别是miRNA是内源的，是生物体的固有因素；而siRNA是人工体外合成的，通过转染进入人体内，是RNA干涉的中间产物。2.结构上，miRNA是单链RNA，而siRNA是双链RNA。3.Dicer酶对二者的加工过程不同，miRNA是不对称加工，miRNA仅是剪切pre-miRNA的一个侧臂，其他部分降解；而siRNA对称地来源于双链RNA的前体的两侧臂。4.在作用位置上，miRNA主要作用于靶标基因3′-UTR区