Pan European Networks - Horizon 2020 - page 56

you can switch off certain genes in
C. elegans
We therefore knocked down particular genes,
one by one, to see if the loss of a specific gene
has an impact on how the roundworm cells can
cope with upcoming protein aggregates and to
see if they develop an effective autophagy. We
knocked down about 3,000 genes in total.
We found that the aggregates do disappear after
time, and if you hit the spot by knocking out an
essential gene for autophagy, the worms can no
longer get rid of these aggregates, so they
remain. With this approach, you can screen for
a particular gene that is important for the onset
of the autophagy. This is actually what we found
and reported in our most recent publication,
presenting the so-called ‘RAB3GAP1/2’ genes
and their protein products as essential for the
onset of the autophagy pathway.
After we initially found the RAB3GAP1/2 in the
C. elegans
model, the next step was to transfer
everything into the mammalian cell system and
then repeat it in the human fibroblasts, which
are non-transformed cells from human
biopsies. Repeating our experiments on human
fibroblasts, we found that RAB3GAP1/2 protein
is an essential factor whenever the cell tries to
switch on an autophagy pathway.
In current studies, we took the mammalian cells
and transferred disease protein aggregates in
these cells. When we knocked down the
RAB3GAP1/2 protein, the cell could no longer
handle these protein clumps and aggregates
increased in the cells and they began to die.
When RAB3GAP1/2 was active and we
challenged the cells with the disease protein,
then the cell could easily handle this aggregate
and the cell functioned properly.
What are the next steps in the
Whenever you are dealing with basic processes
in the cells, like autophagy, there are many
other factors to consider. For example, you have
a network of redundant proteins because the
cell is unable to control this pathway with just
one gene. In fact, there must be some
redundancy, otherwise it’s too dangerous for
the cell.
We are now extending our studies to the whole
network of autophagy genes and proteins in the
H O R I Z O N 2 0 2 0 P R O J E C T S : P O R TA L
The age aspect of Alzheimer’s was almost fully ignored for a long time,
despite it being known that ageing is a major contributor to causing
this disease. The reason for this is that ageing,
per se,
is very hard to
study because it is a multifactorial process and is therefore hard to
tackle pharmaceutically with compounds. In addition, human ageing
is a long-lasting process and is therefore difficult to study.
Consequently, mouse models are frequently used in Alzheimer’s
research, though this has shown no benefit at all as ageing in mice is
very different to ageing in humans.
I am very supportive of the idea of systematically investigating the
biochemistry of ageing neurons. Based on what we already know, one
of the key processes that requires in-depth analysis during the ageing
process is this recycling programme of autophagy. As such, identifying
novel factors and regulators of autophagy is a key issue and important
for future treatments of age-associated brain disorders. I am fully
convinced of this, and therefore the process of autophagy is central to
our investigations.
How was the research undertaken?
Initially, we started off with a very simple animal model, the
Caenorhabditis elegans,
a nematode or roundworm. This nematode is
considered by molecular cellular biologists as a training horse and
genetically shares about 60% of homology with human genes.
are rather easy to handle, manipulate and cheap to use.
Furthermore, it is also easy to target the genes and therefore to establish
transgenic worms; also, the regeneration time is much more rapid
compared to mice, and it is therefore more easy to quickly receive
scientific data compared to mouse work.
We did not employ a wild type
C. elegans
worm line, but rather a
particular transgenic
C. elegans
line that we created prior to the study.
To these transgenic worms, we applied an RNA library carrying 19,000
C. elegans
genes. We could monitor both the build-up of protein
aggregates and the removal of them. Using this particular RNA library,
The transparent
C. elegans
only 1mm in length and
has characteristics that
include a short lifecycle
and a fixed number
of cells
© Andreas Kern
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