rs-antisense genes Nat-sRNA的来源 RDR6 SGS3 DRB? 新 HEN1 There are 2000 pairs of natural cis nat-SiRNA antisense transcripts in Arabidopsis nat-siRNAs corresponding to other cis AGO?nat-siRNA precursor antisense transcript pairs exist and are 24-nt nat-siRNA Detected only under inducible conditions suggesting that this type of regulation RDR6 may not be restricted to a single example SGS3 of overlapping. Genomewide prediction and DRB? DCL1 identification of cis-natural antisense HEN1 nat-SIRNA transcripts in Arabidopsis thaliana. so..r our n duplexes Genome Biol. 6: R30. 2006 Endogenous siRNAs derived from a pair AGO?nat-siRNA precursor of Natural cis-antisense transcripts 21-nt nat-siRNA regulate salt tolerance in Arabidopsis. Cell 123:1279-1291,2005 mRNA cleavage
Nat-siRNA的来源 There are ∼2000 pairs of natural cisantisense transcripts in Arabidopsis nat-siRNAs corresponding to other cisantisense transcript pairs exist and are Detected only under inducible conditions, suggesting that this type of regulation may not be restricted to a single example of overlapping. Genomewide prediction and identification of cis-natural antisense transcripts in Arabidopsis thaliana. Genome Biol. 6:R30,2006 Endogenous siRNAs derived from a pair of Natural cis-antisense transcripts regulate salt tolerance in Arabidopsis. Cell 123: 1279–1291, 2005
SYNTHETIC dsRNA RNA VIRUSES INVERTE PEATS TRANSGENE 动物hc RN工T SIRNA DICER (RNaseI D) IIE 3OH 3OH ATP KINASE 动物 SirNA来 RdDM AMP+p 源于 dsrNA, LIII sPO 3'OH siRNA 后者在细胞质 中经 Dicer 依赖RNA的RNA聚合酶▲RdRP Systemic spread 系统扩散 ( Rnase l)加 3'OH SPOA 工成21-22nt Neighbouring cell SPOA 3'OH SiRNA,随后 SPO 象 进一步扩增放 AMPLIFIED PRODUCTS 扩放产物 NUCLEUS 大或进入细胞 核使染色质异 染色质化 目前在哺乳动物基因组中尚未发现 SiRNA
动物hcsiRNA 目前在哺乳动物基因组中尚未发现siRNA. 动物siRNA来 源于dsRNA, 后者在细胞质 中经Dicer (Rnase III)加 工成21-22nt siRNA, 随后 进一步扩增放 大或进入细胞 核使染色质异 染色质化
Antisense primary transcript AGO3 AGO3 Ping 3end cleavage pong mechanisn PIWVA for rasiRNA biogenesis 3end cleavage WIAUB PIWVAUB Sense prmary transcript A model showing that the 5 end formation of repeat-associated small interfering RNAs (rasiRNAs)associated with Argonaute 3 (AGO3)and aubergine (AUB; or PIWi)are mediated by aUB ( or PIWi)and AGo3, respectively. The mechanism by which the 3 ends of rasiRNAs are generated is still unknown. Scissors represent endonucleolytic cleavage events. This model is based on the studies by Brennecke et al 2007) and Gunawardane et al (2007)
Ping- pong’ mechanism for rasiRNA biogenesis A model showing that the 5′ end formation of repeat-associated small interfering RNAs (rasiRNAs) associated with Argonaute 3 (AGO3) and Aubergine (AUB; or PIWI) are mediated by AUB (or PIWI) and AGO3, respectively. The mechanism by which the 3′ ends of rasiRNAs are generated is still unknown. Scissors represent endonucleolytic cleavage events. This model is based on the studies by Brennecke et al (2007) and Gunawardane et al (2007)
Ras-RNA阻止转座子的转座 While miRNA act in translational repression and mrna cleavage and sirNA act in mrna cleavage. rasirna act to regulate chromatin structure and transcriptional silencing. In Drosophila, mutations in the Piwi proteins that associate with rasirNa lead to sterility and loss of germline cells in both males and females. Transposon repression is not affected by the loss of Dicer within the germline cells revealing that this is the target of the rasirnA pathway. Similar to miRNA and siRNA, the rasiRNa silencing pathway is evolutionarily conserved and homology dependent. when the rasirna pathway is not present, germline cells may undergo retrotransposition which are sensed as dna damage and signal the cell to apoptosis. rasirna is key to the regulatory mechanism of many organisms as part of the rna interference pathway TRENDS in Genetics Vol 20 No.7 July 2004
Rasi-RNA阻止转座子的转座 While miRNA act in translational repression and mRNA cleavage and siRNA act in mRNA cleavage, rasiRNA act to regulate chromatin structure and transcriptional silencing. In Drosophila, mutations in the Piwi proteins that associate with rasiRNA lead to sterility and loss of germline cells in both males and females. Transposon repression is not affected by the loss of Dicer within the germline cells revealing that this is the target of the rasiRNA pathway. Similar to miRNA and siRNA, the rasiRNA silencing pathway is evolutionarily conserved and homology dependent. When the rasiRNA pathway is not present, germline cells may undergo retrotransposition which are sensed as DNA damage and signal the cell to apoptosis. RasiRNA is key to the regulatory mechanism of many organisms as part of the RNA interference pathway
Role of silencing in heterochromatin s-RNA与染色质重建m tion the rna interference consisting of the RNA- induced initiation of transcriptional gene silencing(RITS)complex, Dicer-1(DCR1) and the RNA-directed RNA polymerase Spreading complex(RDRC), processes transcripts HREC SHREC derived from repeat elements into small interfering RNAs(siRNAs). These siRNAs might silence gene expression post- HP transcriptionally in cis. the cir4 complex methylates histone 3 lysine 9 H3K9me (H3K9me), which in turn facilitates stable Repeat elements tethering of the silencing machinery to chromatin through RITS and also allows ruitment of heterochromatin-binding proteins(HPs), such as Swi6/HP1. HP binding creates a platform that allows the RDRC RITS CI Ir4 complex pread of Snf2/Hd DCR1 repressor complex(SHREC)across an SIRNAS=== entire domain shrec can also be recruited to some genomic loci through specific DNA-binding proteins in a process independent of the silencing machinery(not shown). This model is EMBO reports(20078, 723-729 based on the study by Sugiyama et al
si-RNA与染色质重建 EMBO reports (2007) 8, 723 - 729 Role of silencing in heterochromatin formation. The RNA interference machinery, consisting of the RNAinduced initiation of transcriptional gene silencing (RITS) complex, Dicer-1 (DCR1) and the RNA-directed RNA polymerase complex (RDRC), processes transcripts derived from repeat elements into small interfering RNAs (siRNAs). These siRNAs might silence gene expression posttranscriptionally in cis. The Clr4 complex methylates histone 3 lysine 9 (H3K9me), which in turn facilitates stable tethering of the silencing machinery to chromatin through RITS and also allows recruitment of heterochromatin-binding proteins (HPs), such as Swi6/HP1. HP binding creates a platform that allows the spread of Snf2/Hdac-containing repressor complex (SHREC) across an entire domain. SHREC can also be recruited to some genomic loci through specific DNA-binding proteins in a process independent of the silencing machinery (not shown). This model is based on the study by Sugiyama et al, 2007