Judith Haarhuis, postdoc in the research group headed by
Benjamin Rowland, has won the Antoni van Leeuwenhoek Award 2017,
thanks to her fundamental discoveries in chromosome
Her work provides important insight into the way DNA is folded
in the cell, and how the DNA is distributed during cell division.
In both cases, the protein complex cohesin plays a central
The Antoni van Leeuwenhoek awards this prize in January to the
young scientist that has proved to be the most talented in the
previous year. The prize money is 6000 euros, which will go towards
Haarhuis has a dream - to board a microscopic submarine and go
on a voyage of discovery in a human cell. She would ignore all the
miraculous things seen en route, resolutely setting course for the
cell nucleus. Because it is in that ball measuring just a few
thousandths of a millimetre across, that two meters of DNA is
folded. Her aim is to find out, firstly how that is possible, and
secondly, what it means for our body and our lives. 'How fantastic
would it be to follow our own exciting experiments with the naked
eye,' says Haarhuis.
With these experiments, she and her colleagues from the
Netherlands Cancer Institute have already made a number of
important discoveries about the way in which these two meters of
DNA are folded.
Loops with a ring around them
DNA becomes folded into small loops that can be made bigger.
This flexibility is of great importance for regulation of genes.
Haarhuis has demonstrated experimentally for the first time that
these loops are made larger by a small ring at the bottom of the
That ring is a protein complex that is - appropriately - called
cohesin. It plays a crucial role in the folding of DNA and forms
the core of the research carried out by Haarhuis. With her
discovery that cohesin regulates the length of the loops, she
confirmed a hypothesis that had already been proposed in 2001 but
had never been proven.
Cohesin works like a padlock that has only one point for entry
and exit. An important role is played by a protein called WAPL that
can open the padlock. This discovery has given researchers much
more room for manoeuvre, because now they can switch off WAPL and
see what happens to the loops of the DNA. What they saw is that
there's a lot going on. 'Once you take away WAPL, the loops in the
DNA become much larger, and those loops also remain very long',
says Haarhuis. 'You will then get many long loops and DNA strings
that are rigid. They cannot make new movements over long distances.
That is dramatic, because this seriously restricts gene
regulation.' What the researchers do not yet understand is how the
WAPL mechanism works. Haarhuis: 'WAPL has no enzymatic effect in
any case. It's probably a kind of chemical bond, but we don't know
which one yet.'
Explaining the X-shape of chromosomes
Cohesion is also of great importance for cell division. Just
before splitting into two identical chromatids - one for each new
cell - the chromosomes in the cell assume their typical
X-form. That X is held firmly together at the middle by a few final
cohesin rings. Cohesin has then already disappeared around the arms
of the X. Haarhuis has discovered how important this phase of the
X-form is. Haarhuis: 'If you take away WAPL, then beautiful
X-shaped chromosomes are no longer formed, or the chromosomes end
up in the wrong daughter cell. This has all kinds of unpleasant
consequences, including the risk of cancer.'
About Judith Haarhuis
Judith Haarhuis has already built up a track record of
high-profile scientific publications in her short career. Research
leader Benjamin Rowland, who nominated her for the award, calls her
a brilliant thinker and exceptionally talented experimental
researcher. He praises her creativity, perseverance and contagious
'This is too much praise', she says. 'This is really group work.
Our research group and the other groups we collaborate with in the
Netherlands Cancer Institute are simply amazing.'
Judith Haarhuis studied biomedical sciences at Utrecht
University and completed the master's programme entitled Cancer
Genomics and Developmental Biology. After an internship in the USA,
she did her PhD research in the Netherlands Cancer Institute, in
the research group headed by Benjamin Rowland. Having finished her
PhD at Utrecht University, with René Medema as promoter, she is
continuing her postdoc in the Rowland group.