The question to be addressed is Why exogenous dsRNA can inhibit expression of genes homologous To that rna?
12 The question to be addressed is “Why exogenous dsRNA can inhibit expression of genes homologous to that RNA?
dsRNA HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHT Exogenous dsRNA cell membrane 外源双链RNA dicer nucleus B HHHHHHHHHHIHHHHHf H SiRNA duplex HHHH HHH Figure 17-30 chromatin remodeling RISC HHHHH RNAi silencing RISC IHH amm HHE translational amplification inhibition 13
13 Figure 17-30 RNAi silencing Exogenous dsRNA 外源双链RNA
The targets of the RNAi-directed gene Silencing 1. Degradation of the target mRNA (9I 起靶标mRNA的降解), 2. Inhibition of translation of the target mRNA(抑制靶标mRNA的翻译 3. Silencing the gene transcription from the target promoter(引起靶标启 动子的转录沉默) 14
14 The targets of the RNAi-directed gene silencing 1.Degradation of the target mRNA (引 起靶标mRNA的降解), 2.Inhibition of translation of the target mRNA (抑制靶标mRNA的翻译), 3.Silencing the gene transcription from the target promoter (引起靶标启 动子的转录沉默)
The heart of the rnai mechanism 1. Dicer: an RNaseIII-like multidomain ribonuclease that first processes input dsRNA into small fragments called short interfering RNAs(siRNAs) or microRNAs (miRNA). Dicer then helps load its small RNA products into RISC 2. RISC (RNA induced silencing complexes (RNA诱导的沉默复合体): a large multiprotein complex that direct the bound siRNA or miRNA to its target and inhibit the target gene expression 15
15 The heart of the RNAi mechanism 1. Dicer: an RNaseIII-like multidomain ribonuclease that first processes input dsRNA into small fragments called short interfering RNAs (siRNAs) or microRNAs (miRNA). Dicer then helps load its small RNA products into RISC. 2. RISC (RNA induced silencing complexes) (RNA诱导的沉默复合体): a large multiprotein complex that direct the bound siRNA or miRNA to its target and inhibit the target gene expression
Structural basis for double- stranded DIcer: RNA Processing by Dicer lan ]. MacRae, 13 Kaihong Zhou, 3 Fei Li, Adrian Repic, Angela N Brooks, 1 W. Zacheus Cande, Paul D. Adams, 4 Jennifer A. Doudna2 SCIENCE VOL 311 13 JANUARY 2006 Human Dicer Structural organization A paz domain binds the Giardia Dicer: 贾第鞭毛虫 end of the dsrna B Two rNase iii domains 155. T1 OH Der Mg 5 1o 2o 40 ---Other non-conserved domains 16
16 Dicer: Structural organization: ---A PAZ domain, binds the end of the dsRNA ---Two RNase III domains ---Other non-conserved domains. 贾第鞭毛虫