Transcript Epigenetic modification of DNA

Epigenetic modification of
DNA
Methylation is the gradual addition of
chemical units known as methyl groups to
genes, and as these groups accumulate, the
gene gradually shuts down.
DNA methylation is the addition of a methyl group
to the carbon-5 position of cytosine residues.
• Alterations in DNA
methylation are
regarded as
epigenetic and not
genetic changes,
because they do not
materially affect the
genetic code.
• Epigentics webcast
Webcast - 11/28/2007
- The Burrill Report
The Human Epigenome Project
(HEP)
• aims to identify, catalogue and interpret
genome-wide DNA methylation patterns of all
human genes in all major tissues.
• Methylation is tissue specific and is of major
importance in the regulation of gene expression
during development.
• Methylation is the only flexible genomic
alteration which can change the way the
genome functions under exogenous influence.
• It constitutes the main, and so far missing, link
between genetics, disease and the environment
that is widely thought to play a decisive role in
the development of virtually all human
pathologies.
cancer
• The human body is prone to developing cancer,
from a very early stage of life, until the end of
life.
• The human genome has several built in tumour
suppressor genes, whose protein products
suppress the formation of tumours. It is
important for these genes to continue
expressing their tumour suppressor proteins as
long as the person lives.
• One way these genes can lose their ability to
make protective proteins is through methylation.
• One way these genes can lose their ability
to make protective proteins is through
methylation.
• The pattern of methylation observed in
cancer generally shows a dramatic shift
compared with that of normal tissue.
Dolly (1996-2003)
The first cloned mammal
• Inefficient reprogramming of epigenetic marks is
the main reason for the poor health of cloned
animals.
Human Epigenome Project
• One of the aims of the Human Epigenome Project (HEP)
is to generate tissue-specific DNA methylation reference
profiles of the human genome.