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Mechanobiology of Disease
Poster Abstracts
108
27-POS
Board 27
Cytoskeleton Self-organization in Epithelial Cells
Salma Jalal
1
, Yee Han Tee
1
, Virgile Viasnoff
1,2,3
, Alexander Bershadsky
1,4
.
1
National University of Singapore, Singapore, Singapore,
4
Weizmann Institute of Science,
Rehovot, Israel.
2
National University of Singapore, Singapore, Singapore,
3
Centre National de la
Recherche Scientifique, Singpaore, Singapore,
Cytoskeleton self-organization and reorganization is necessary to enable fundamental cellular
processes such as extracellular adhesion to matrix and/or other cells, polarization, as well as
migration. Remodelling of the actin cytoskeleton is known to play a key role in regulating the
process of epithelial-messenchymal transition (EMT), where epithelial cells switch to a more
fibroblast-like phenotype and can participate in metastatic cancer progression. However, the
current understanding of how actin reorganization regulates EMT is limited by concurrent
changes to cell-cell adhesions and cell morphology present in the colony assays used in most
studies of the process.
In order to remove the influence of cell-cell adhesions and cell shape changes from our
observation of actin dynamics, we use long-term live imaging to observe epithelial cells
maintained in standardized conditions. Single cells were geometrically confined on circular
matrix or cadherin coated islands. We first compared actin self-organization in keratinocytes
(basal epithelial cells) to our prior understanding from fibroblasts, and next look at it in bladder
carcinoma cells (simple epithelial cells) before and after growth factor induced EMT.
Preliminary studies show clear differences between the self-organization of actin in keratinocytes
when compared to fibroblasts, as well as in the carcinoma cell line before and after EMT. In
keratinocytes the actin cytoskeleton self-organizes into a symmetric radial pattern that:-
• Depends on spread area.
• Is not significantly changed upon attachment to cadherin adhesions instead of focal adhesions.
• Does not break symmetry. This is in stark contrast to fibroblasts, where actin self-organizes
into an initially symmetric pattern that subsequently becomes asymmetric.
In bladder carcinoma cells plated on fibronectin islands, the actin cytoskeleton organizes into
circumferential bundles, membrane protrusions, ventral stress fibres and contractile geodesic-like
structures. After EMT induction we have seen radial fibre like structures begin to appear with
more prominent geodesic-like structures.