Our cells - and ultimately our entire body - are
governed by genes, the functional units of our DNA. Gene expression
rests on two very important processes, called transcription and
translation. These two processes were thought to function
independently. But the research group of Reuven Agami from the Netherlands Cancer
Institute (NKI) now shows that there is indeed a link between them.
The group's work was published
in the journal Cell on April 6.
During gene expression, first, the DNA is 'read' and the gene is
copied into a string of RNA. This is called transcription. Next,
this piece of RNA moves outside the cell nucleus (where our DNA is
located), and cell structures called ribosomes use it as a template
to make a protein. This process is called translation. These two
processes where thought to be independent. They are governed by
different cell structures, and on top of that they take place at
different locations within the cell. Reuven Agami's team has now
found proof that there is indeed a link between the two: the faster
the rate of transcription, the more efficiently the RNA's are
translated into proteins.
"There already were some indications that this such a connection
might exists", comments Agami. "We managed to demonstrate it and to
show how it works. We tried different things, for instance,
artificially increasing the amount of RNA of certain genes. Because
maybe the mechanisms is just that the more RNA is present, the more
efficiently it gets translated into proteins. But no, this turned
out to not be true."
How does it work then? Through epigenetics. Epigenetics is the
term used for all types of modifications that influence our genes,
other than actually changing the code of the DNA. A common type of
epigenetic mechanism is methylation. When a methyl group is added
to RNA in the coding region, it acts as a kind of concealing tape
that reduces the efficiency of reading that piece of genetic code.
"We observed that the faster the DNA is transcripted, the less
likely the RNA is to be methylated. Which has a positive effect on
the RNA translation, resulting in more proteins", says Agami.
This important fundamental new insight doesn't have any
applications yet. Though it could mean that in the future we might
influence gene expression by modifying the methylation process. But
it is fascinating to see how much we still have to discover when it
comes to DNA and the way our genetics works.