B1.2025: Polarity of cortex mechanics and fluidity
Lead PI: Andreas Janshoff
Collaborating PIs: Sarah Köster, Claudia Steinem, Timo Betz
Overarching research question: Does mechanical polarity exist in epithelial cells and if so, how does it arise and depend on functional cell-cell contacts?
The goal of the project is to elucidate the impact of the apical-basal polarity of confluent cells on the mechanical properties of the basal and apical cortex. 2D and 3D cell cultures combined with strategies to obtain cell-membrane fragments with associated cortex structures will be used to investigate the impact of apical-basal polarity on the viscoelastic properties of epithelial cells. The focus lies on the development and maturation of cell polarity over time. This will be achieved by confocal imaging of marker proteins and single-cell indentation experiments that can address the change in cortical tension, fluidity, and area compressibility of cells in different states and environments. The reversal of polarity in 3D culture enables us to assess both sides of the cell. Simultaneously, we aim to reinstate the natural state of cell membrane sheets by activating cortical treadmilling of actin filaments and introducing components that either strengthen or weaken the cortex structure using cross-linkers such as α-actinin or simple multivalent cations.
Core field: experimental biophysics
PhD training objectives: biophysical characterization methods (confocal/STED imaging, AFM); cell biological methods (cell culture, immunostaining, CRISPR-CAS); data analysis (image processing, force-relaxation data).