Biophysical Society Thematic Meeting | Singapore

Mechanobiology of Disease

Poster Abstracts

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.

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