2. What is gene silencing?
Gene silencing is the regulation of gene
expression in a cell to prevent the expression
of a certain gene.
Gene silencing is often consider the gene
knockdown.
3. Why gene silencing?
Prevent the gene expression
Drug discovery
Reduce or eliminate the production of
protein from its corresponding gene
4. INTRODUCTION
Epigenetic process of gene regulation
A gene which would be expressed(turned
on)under normal condition and (switch off) by
machinery in the cell.
It is same as gene knock down but totally
different form gene knock out
6. TRANSCRIPTION METHOD GENE
SILENCING
Antisense RNA has the
opposite sense to m
RNA.
The presence of
complimentary sense and
antisense RNA interferes
with gene expression at
the level of RNA
processing or possible
translation.
This technology widely
used in plants for gene
inhibition.
7. The antisense effect of a oligonucleotide sequence
was first demonstrated in 1970s by Zamecnik and
Stephenson, in Rous sarcoma virus.
consist of 15–20 nucleotides, which are
complementary to their target mRNA.
combined with target mRNA, which degraded by the
enzyme RNase H.
blocking the disease causing protein production has
can result in improvement
the treatment of certain disease which otherwise
would be difficult to treat using normal methods.
8.
9. Histone Modification
Histone proteins act to package DNA, which wraps
around the eight histones, into chromosome
act in diverse biological processes such as
activation/inactivation, chromosome packaging, and
DNA damage/repair.
10. Acetylation • It is the
introduction of an Acetyl
functional group to the
Lysine amino acid of the
his tone tail.
These reactions are
catalyzed by enzymes
with "histone
acetyltransferase" (HAT)
or "histone deacetylase"
(HDAC) activity.
11.
12. Genome imprinting
Genetic phenomenon by which certain
genes are expressed in parent-of- origin
specific manner.
Genome imprinting have been
demonstrated in insect mammalian and
flowering plant.
13.
14. RNA interference (post-
transcriptional gene silencing
Exogenous dsRNA is induced which binds to
known complementary mRNA
Cellular mechanism that degrades the unwanted
mRNA in the cytoplasm
Sequence specific RNA degradation
dsRNA can be
1. siRNA
2. miRNA
15. Application
• Biological functions
1. Down regulation of genes: important in
translational repression and in the
regulation of development
2. Up regulation of genes: dubbed RNA activation
3. Evolution: The ancestral function of the RNAi
system is generally agreed to have been immune
defense against exogenous genetic elements such
as transposons and viral genomes
16. Technological applications
• Technological applications
1. Gene knockdown: to study the function of genes in
cell culture and in vivo in model organisms
2. Functional genomics: particularly attractive
technique for genomic mapping
3. Medicine: use of short interfering RNA mimics;
seen as a promising way to treat cancer by
silencing genes differentially unregulated
4. Biotechnology use
