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Hello. My name is Andres Blanco.
I'm an assistant professor at
the University of Pennsylvania.
Today's lecture is going to
be on Cancer Epigenetics.
Now before we can understand
the cancer part, we need to
understand the epigenetics part.
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So what is epigenetics?
Well, we all know
genetics is the study of
heredity and the variation of
inherited characteristics,
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so what about epigenetics?
Well, let me start
with few examples.
Let's look at these plants here.
You'd think that these are
different strains of plants,
but they're actually identical.
They have these
different petal shapes,
but the offspring of these
plants will look like this
one and the offspring of these
plants will look like this one,
and then let's look
at these mice here.
These are also all
genetically identical despite
the fact that you probably think
they come from
different strains.
The offspring have the same
coat color that the parents
have and then let's think
about these cells here.
Different cell types of the
mammalian organism, they're
also very different in
functionality and in appearance,
but of course if it came from
the same individual they
are genetically identical,
so what's going on here?
In the case of the plants,
a gene that's controlling the
petal shape, it's actually
silenced by a modification
of DNA called DNA
methylation.
In the case of the mice,
a gene that's controlling
the coat color is set in the
on-state or the off-state
depending on whether
a retrovirus
which is inserted into
the genome is right near
that gene is itself in on or
an off state and that
state is heritable
over generations
and then looking at
the different cell types we know
that they all start from
one cell the zygote,
but over development the cells
mature into very
different cell types
expressing very different
gene expression programs and
these gene expression
programs are quite stable.
Once these identities
are acquired as
mature cell types they
tend not to change,
so these are a few
examples of epigenetics.
Now, there's no one accepted
definition of epigenetics,
but for the purposes of
the talk we can use this.
We could think of epigenetics
as a study of
heritable phenotypic
changes not involving
alterations in the DNA sequence.
