Gene silencing by shakira sulehri 2013

Gene silencing

1. Gene Silencing:




BY
SHAKIRA SULEHRI
2013

2. Gene Silencing:
The term gene silencing is generally used to describe the "switching off" of a gene by a
mechanism other than genetic modification. That is, a gene which would be expressed
(turned on) under normal circumstances is switched off by machinery in the cell.
Interruption or suppression of the expression of a gene at transcriptional or translational
levels. Scientists have been working on strategies to selectively turn off specific genes in
diseased tissues for the past thirty years:
1980's - antisense oligodeoxynucleotides (ODNs)
1990's - ribozymes
2000's - RNA interference (RNAi)
Comparison of different gene silencing strategies.
Agent Mechanism Result
Most drugs Bind to target protein Protein inhibition

3. RNase H-
independent
ODNs
Hybridize to target mRNA Inhibition of
translation of the
target protein
RNase H-
dependent ODNs
Hybridize to target mRNA Degradation of the
mRNA by RNase H
Ribozymes and
DNA enzymes
Catalyze cleavage of target mRNA Degradation of the
mRNA
siRNA Hybridize to target mRNA by its antisense
strand and guide it into endoribonuclease
enzyme complex (RISC)
Degradation of the
mRNA

Comparison of gene silencing strategies