Cell News 04/2018
23
While rigidity sensing and mechanotransduction has tradition-
ally been attributed to focal adhesion complexes, the attach-
ment of keratinocytes in the skin epidermis to the extracellular
matrix is additionally mediated by hemidesmosomes. Intra-
cellularly, the hemidesmosomal complex links transmembrane
adhesion receptors to the actin cortex, to microtubules, and to
the intermediate filament (IF) network.
Rudolf Leube
(RWTH
Aachen University, Germany) described in his talk the emer-
gence of highly coordinated hemidesmosome-focal adhesion
patterns during substrate adhesion and cell spreading, which
seem to be responsible also for maintaining cell polarity and
for orchestrating the directed assembly of focal adhesions at
the cell's leading front and disassembly at the cell rear end.
Following up,
Cécile Leduc
(The Institut Pasteur, France) pre-
sented evidence that the spatial distribution of the cytoplasmic
IFs in polarized cells results from the cooperation of an ac-
tin-dependent retrograde flow and anterograde and retrograde
dynein-dependent microtubule-dependent transport.
The first day was concluded by a controversial talk by
Ajay Ti-
jore
(National University of Singapore, Singapore) who exposed
tropomyosin-deficient cancer cells to mechanical stretch of
various amplitude and frequency, and investigated cell elonga-
tion, re-alignment, and stretch-induced apoptosis mediated by
calcium-activated calpain activity. After tropomyosin rescue,
the cells no longer responded to mechanical stretch with apop-
tosis but with increased growth, prompting the highly debated
speculation that mechanical stretch may have positive thera-
peutic effects in cancer.
The first day ended with a welcome dinner for all conference
attendees and speakers. This type of “round table” was a
novelty at the POC and provided an opportunity especially for
young scientists to connect with seasoned investigators and to
establish new collaborations.
Second day:
The second day started out with a lecture by
Anne-Cécile
Reymann
from the IGBMC in Strasbourg. In her talk, Dr. Rey-
mann explained how in vivo endogenous labeling of proteins
in combination with state-of-the-art microscopy can be used
to analyze the dynamics of various molecular components of
the cortical layer in C. elegans embryos. Her data demonstrate
how mechanical remodeling of the actin structure mediated by
cortical flows plays a role in the formation of contractile rings.
In the next lecture,
Ana Suncana Smith
from the Department
of Physics at the FAU in Erlangen-Nuremberg showed how
regional changes in the physical properties of cell membranes,
such as fluidity, can have major impacts on cellular structure
and function including cell-cell adhesion and interaction with
the extracellular matrix.
Jona Kayser
from the Hallatschek-Lab at the University of
California (Berkley) moved in his talk to the multicellular level
and demonstrated how mechanical cell interactions influence
clonal evolution in a microbial model system (yeast cells). He
was able to show that the collective motion of cells from a
central core to the periphery can attenuate selective evolu-
tionary pressure on cells. Using a combination of microbial
experiments and computational modelling, he demonstrated
that cells carrying costly mutations – e.g. mutations that
confer resistance to chemotherapeutic agents in solid tumors
– can be carried to the outer regions of a spherically expanding
cell mass by physical cell-cell interaction forces without having
to actively divide. This finding might have critical implications
for the understanding of clonal evolution in solid cancer as it
explains how cells with genetic mutations which do not pro-
vide a survival advantage (such as a high cell division rate) in
early tumor stages can still survive until later stages when their
properties become critical for survival.
Viola Vogel
(ETH Zürich) continued the symposium with a talk
on how the stretching of the extracellular matrix can influence
Kamran Hosseini received the young scientists award (1000 EUR)
sponsored by the DGZ
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