Please wait while the transcript is being prepared...
0:00
Welcome everyone to Chapter 2
of the HS short talk series,
Nuclear Receptors as
Therapeutic Targets.
This chapter will be on the
nuclear receptor superfamily
and its classification
and basic features.
0:18
As mentioned in Chapter 1,
nuclear receptors
are also termed
ligand-activated
transcription factors,
and they have a specific
domain architecture
that we will have a look
at in the next chapter.
Here, we will now discuss the
different classifications
of these transcription factors
and look how we can group
them into different families.
0:41
One classification system
for nuclear receptors is
their cellular localization.
Here, on the left figure,
you see how a typical
transcription factor might work
responding to an
extracellular signal,
like from a growth factor.
That, in turn, starts an
intracellular signal cascade
that in the end activates
the transcription factor,
for example by phosphorylation,
and then the transcription factor
will move into the nucleus,
bind to the DNA,
and regulate gene expression.
Some nuclear receptors
act similarly.
They wait in the cytoplasm
without their ligand bound
and are bound to a so-called
inhibitor complex,
or heat shock proteins.
These steroid hormone receptors
wait for their ligand
to enter the cytoplasm,
bind to the receptor,
and then this ligand
binding will release
the nuclear receptor from
the inhibitor complex,
enable its nuclear translocation
and the binding to the
DNA response element.
Then there are other
nuclear receptors
that already wait bound to
the DNA for their ligand,
so they are, from the start,
in the nucleus and wait
for the ligand to bind
before they initiate
gene expression.
We will see that those
two different types
of nuclear receptors
also have consequences
on their ability to
induce and repress genes,
whether they wait in the
cytoplasm for the ligand
or whether they are
already DNA-bound.
