Cell News 04/2018
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the availability of extracellular molecular binding sites, and
how these changes may affect outside-in cellular signaling.
By using mechanosensitive binding probes that were devel-
oped in her lab and which bind specifically to relaxed (but not
to stretched) fibronectin fibers, she showed how mechanical
changes in the extracellular matrix play a role in crucial pro-
cesses involved in cell- and tissue formation.
Continuing the session on the biophysics of matrices,
Florian
Rehfeldt
(GAU Göttingen) demonstrated in his lecture how a
biomimetic ECM model based on hyaluronic acid can be used
to simulate various microenvironments with different mechan-
ical properties, especially varying degrees of elasticity. Using
this model, he demonstrated how stress fiber morphology is an
early structural marker of human mesenchymal stem cell dif-
ferentiation. In addition, he showed impressively how cytoskel-
eton structure can be quantified using life cell imaging and a
custom-made and publicly available filament sensor which was
developed in his lab.
Finally,
Pere Roca Cusachs
(PCB, Barcelona) demonstrated how
cells sense the rigidity of the surrounding matrix and how they
respond to it. Using very elegant experiments, he and his group
have deciphered how changes in ECM rigidity are transmitted
to the nucleus, and which biochemical pathways are activated
this way. Accordingly, the YAP pathway plays a crucial role in
transforming mechanosensation signals into transcriptional
adaptions. Ultimately, a computational molecular clutch model
can quantitatively predict the role of several cytoskeletal pro-
teins including talin in the formation of a cellular response to
ECM stiffness changes.
The second day was concluded with a contributed talk by
Justyna Bobrowaska
from the Polish Academy of Sciences,
Krakow. In her talk, she explained how the combination of two
techniques – atomic force microscopy and time of flight of sec-
ondary ions mass spectrometry (ToF SIMS) can be combined to
identify biophysical and structural alterations of cancer cells. In
the presented experiments, AFM was used to characterize the
physical properties of melanoma cells in different stages. The
application of ToF SIMS enabled her to identify biological al-
terations in the composition of the cell membrane of the same
melanoma cells, which might be of translational relevance as
potential therapeutic and diagnostic markers can be identified
using this technique.
After the talks, all participants reconvened at the Leipzig Uni-
versity Department of Physics building for lunch and the post-
er-session. The organizers of the conference had the difficult
task to select one out of 32 poster contributions for the young
scientist award of the DGZ. The choice fell on
Kamran Hosseini
from the BIOTEC lab at Technical University of Dresden for his
poster entitled “EMT-induced changes of cortical contractil-
ity and stiffness in breast epithelial cells”. Kamran Hosseini
demonstrated how atomic force microscopy with a modified
wedged cantilever can be used to measure the cortical stiffness
and contractility of suspended single cells. This technique was
used to characterize breast epithelial cells before and after the
chemical induction of EMT, and he discovered that both stiff-
ness and contractility decrease with the induction of EMT. The
referees agreed that his work was of high scientific relevance,
and that the experiments were carried out in a methodically
elegant and demanding way.
In the afternoon of the second day, all invited speakers were
offered to visit the famous Bach Museum and to attend a
private concert held by the Camerata Bachiensis, an ensemble
specializing in the performance of baroque musique. After-
wards, the participants were invited to join Prof. Käs on one
of his famous guided tours through Leipzig. The evening was
spent at the Ratskeller, a traditional Leipzig restaurant in the
town hall basement. Those who were interested in exploring
the local night life convened thereafter in the Moritzbastei, a
bar famous amongst Leipzig students and scholars.
Third day:
The final day got off to an early and stimulating start, with
Heiko Rieger
(Saarland University) discussing a system that
has become key to modern therapeutic approaches: the human
immune system's own response to attacking cancer cells. While
this general concept of using the body's immune response has
led to the most recent Nobel Prize in medicine and a growing
number of advanced therapies, the underlying cellular bio-
physics governing immune cell response to cancer is not well
understood. Using a broad scope of theoretical approaches, he
showed how his group, through collaborations with experimen-
talists, has started to uncover many of these interactions on
the physical level. They range from dynamic organization of the
immunological synapse, search-and-destroy strategies of mi-
grating natural killer (NK) cells and the various ways that these
cells can induce an apoptotic signal to their targeted victims.
Afterwards,
Moritz Kreysing
(Max Planck Institute of Molecular
Cell Biology and Genetics) introduced an innovative method for
inducing pinpointed hydrodynamic flows inside of cells through
thermoviscous expansion. Using this technique, he was able to
influence the polarization of developing cells by concentrating
the localization of key proteins such as PAR-2. Additionally,
he discussed how this exciting method could also be utilized
for probe-free cytoplasmic microrheology inside of living cells,
potentially paving the way for minimally-perturbing in-situ
studies of cell mechanics.
Next up,
Lydia Sorokin
(University of Münster) shifted focus
to the formidable barrier of the basement membrane, which
greatly slow down the passage of cancer and immune cells
between different tissue compartments. The laminin class of
proteins is critically responsible for controlling this barrier
MEETING REPORT
