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RNAi Mechanism
INTERFERENCE....
The Central Dogma
DNA (double-stranded)
RNA (single-stranded)
Protein
When good RNA goes bad....
Viruses can
make doublestranded RNA
How did cells evolve to fight this?
When good RNA goes bad....
Cells sense doublestranded RNA and
activate a response
called RNAi
Understanding how
RNAi works is the
key to using it as a
genetic tool and for
therapy
Dicer cuts dsRNA into short RNAs
Vanhecke, D.; Janitz, M. Drug Discov. Today, 2005, 10, 205-225.
Role for a bidentate ribonuclease in the initiation step of RNA interference Emily Bernstein, Amy
A. Caudy, Scott M. Hammond & Gregory J. Hannon
2001
Bernstein
et al.
Cloned Dicer, the RNase III enzyme that is evolutionarily conserved and
contains helicase and PAZ domains, as well as two dsRNA-binding domains.
RNAi functions in many different organisms
dsRNA
How do small dsRNAs turn genes off?
Model for translational repression
M7GpppG
RISC recognizes a target
RISC
AAAAAA.........
Model for translational repression
M7GpppG
DCP GW
RISC
Other proteins are also recruited –
either along with RISC or later
other
AAAAAA.........
Least well understood - Arabidopsis as a model….