Garcia Arcos, J. M. | Search bioRxiv

bioRxiv2022

Technical insights into fluorescence lifetime microscopy of mechanosensitive Flipper probes

Measuring forces within living cells remains a technical challenge. We developed hydrophobic mechanosensing fluorescent probes called Flippers, whose fluorescence lifetime depends on lipid packing and can report on membrane tension. Here, we describe technical optimization of the probe imaging, and diverse characterizations in various biological and in vitro systems. We provide a guideline to measure biophysical parameters of cellular membranes by FLIM microscopy with Flipper probes, providing evidences that flippers can report long range forces in cells, tissues and organsi.

biophysics↗

bioRxiv2021

A mechano-osmotic feedback couples cell volume to the rate of cell deformation

Mechanics has been a central focus of physical biology in the past decade. In comparison, the osmotic and electric properties of cells are less understood. Here we show that a parameter central to both the physics and the physiology of the cell, its volume, depends on a mechano-osmotic coupling. We found that cells change their volume depending on the rate at which they change shape, when they spread, migrate or are externally deformed. Cells undergo slow deformation at constant volume, while fast deformation leads to volume loss. We propose a mechano-sensitive pump and leak model to explain this phenomenon. Our model and experiments suggest that volume modulation depends on the state of the actin cortex and the coupling of ion fluxes to membrane tension. This mechano-osmotic coupling defines a membrane tension homeostasis module constantly at work in cells, causing volume fluctuations associated with fast cell shape changes, with potential consequences on cellular physiology.

biophysics↗