2002.09.17 drosha. 121th lab meeting 석사 2 년 박 은 실
TRANSCRIPT
2002.09.17
DroshaDrosha
121th Lab meeting121th Lab meeting
석사 2 년
박 은 실
Lin-4, Let-7Lin-4, Let-7
What is RNAi ?
A form of posttranscriptional gene silencing, in which dsRNA induces degradation of the homologous mRNA, mimicking the effect of the reduction, or loss, of gene activity.
Kim VN., Kim VN., J Korean Med SciJ Korean Med Sci . 2003 . 2003
MicroRNAMicroRNA
•Small, Non coding RNAs
•21~25nt long
•Negatively regulate gene expression
•Lin-4, Let-7
•RNAse Ⅲ type enzyme
Kim VN., Kim VN., J Korean Med SciJ Korean Med Sci . 2003 . 2003
stem loops involving the mature miRNAs (red) The miRNAs* (blue)
Examples of Metazoan miRNAsExamples of Metazoan miRNAs Examples of Metazoan miRNAsExamples of Metazoan miRNAs
David P. Bartel. David P. Bartel. cellcell. 2004. 2004
The molecular hallmarks of The molecular hallmarks of lin-4lin-4
The molecular hallmarks of The molecular hallmarks of lin-4lin-4
Lin He and Gregory J.HannLin He and Gregory J.Hannon.on. Nature Nature. 2004. 2004
MiRNAs and SiRNAs — what’s the differeMiRNAs and SiRNAs — what’s the differencence
MiRNAs and SiRNAs — what’s the differeMiRNAs and SiRNAs — what’s the differencence
• terms of their molecular characteristics, biogenesis and effector functions• share a common RNase-III processing enzyme, Dicer, and closely related effector complexes, RISCs, for post-transcriptional repression
•Specific precursor• bind to the target 3′ UTRs through imperfect complementarity at multiplesites
miRNAmiRNA
•sampled more randomly from long dsRNAs•form a perfect duplex with their targets at only one site
siRNAsiRNA
The current model for the biogenesis and post-transcriptional
suppression
The current model for the biogenesis and post-transcriptional
suppression
Two processingTwo processing
First: nascent miRNA(pri-miRNA) → ~70nt precursor (p
re-miRNA)
Second: → 21~25nt mature miRNA
Drosha, Dicer: ds RNA specific endonuclease
Lin He and Gregory J.HannLin He and Gregory J.Hannon.on. Nature Nature. 2004. 2004
The structure and function of the Dicer familyThe structure and function of the Dicer family
Dicer1 and Dicer2Dicer1 and Dicer2•Deficiency in Dicer1 disrupts the processing of pre-miRNAs• loss of Dicer2 affects the production of siRNAs, but not miRNA maturation.
=PAZ domain is only present in Dicer1, but absent in
Dicer2
Argonaute (AGO) proteins include PAZ domain and a piwi domain.
Lin He and Gregory J.Hannon.Lin He and Gregory J.Hannon. Nature Nature. 2004. 2004
Post-transcriptional repression by miRNAsPost-transcriptional repression by miRNAs
• Lin-4 와 lin-14• Let-7(worms), Bantam(flies), miR30 (mam
mal) – negatively regulate• mir-196 = animal 에서 유일하게 그 target
인 Hoxb8 에서 base pairing 이 perfect하여 mRNA 의 destruction 일으킴
• miR-172 = 유일하게 coding 영역에 존재하며 plant 에서 유일하게 repressor로 작용
C. elegans : 116
C. briggsae : 50
D. melanogaster : 78
A. thaliana : 48
Rice : 28
Mouse : 207
Rat : 185
Human : 191
miR-26a and miR-99a miR-26a and miR-99a expression is reduced expression is reduced in human lung cancer in human lung cancer
cell line.cell line.
In vitroIn vitro processing of miRNA by Drosha processing of miRNA by DroshaIn vitroIn vitro processing of miRNA by Drosha processing of miRNA by Drosha
2004.08.05
AGO AGO proteinprotein