RNA interference:

Kill the messenger!

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conclusion: dsRNA triggers potent and specific gene silencing

inject worms with dsRNAcorresponding to a geneinvolved in wiggling (unc-22)

Discovery

Biochemistry to Examine Structure

short interfering RNA: siRNA

21 nt long, dsRNA:

P

P

Dicer generates siRNAs

RNase III endonuclease

Mix cell extractwith dsRNA

21-mer

Berstein et al. Nature (2001)

RNA interference (RNAi)dsRNA

siRNA

Dicer

RISC

AAAAcapmRNA

AAAAcapmRNA

Timeline

1998

1999

2000

2001

2002

1990 cosuppression of purple color in plants

dsRNA injection in wormsshort RNAs identified in plants

RNAi shown in vitro

RISC activity partially purified

siRNAs identifiedDicer identified

RNAi used against HIVgenome-wide RNAi screens begin

Big Potential for Small RNAs

Adapted from Ryther et.al. Gene Therapy (2005)

S2 Drosophila cells spread on coated glass surface via lamellipodia

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are needed to see this picture.

Example of RNAi experiment