Laboratoire Matière et Systèmes Complexes

There will be a live diffusion with Zoom :

Monday March 27th, 11h30 in room 454 A.

Please contact Jean-Baptiste Manneville to attend the visio-seminar.

Measuring forces with Flipper probes

Chloé Roffay

University of Geneva (Roux lab) & IMP Vienna (Pinheiro lab)

Stem cells grow in environments that offer a variety of physical cues : for instance, the trophectoderm is stretched during the formation of embryonic cavities (Chan et al, 2019) or mesenchymal stem cell differentiation is affected by osmotic pressure (Guo et al, 2017). Indeed, growing evidence supports that, in addition to molecular cues, mechanical forces are an essential source of morphogenetic information, contributing both for shaping and patterning the developing embryo. However, measuring forces within living systems remains technically challenge. With this in mind, we developed hydrophobic mechanosensing fluorescent probes called Flippers (Roffay et al, 2022), whose fluorescence lifetime depends on lipid packing and on membrane tension. Flipper probe was recently used to investigate the coupling between plasma membrane tension and cell volume during osmosis (Roffay et al, 2021) as well as the central role of ion channels and the cytoskeleton to maintain this coupling. Here, we describe technical optimization of probe imaging, and report successful staining in various biological systems, from encapsulated epithelial monolayers, Xenopus explants to 3D mESC gastruloids and mouse embryos. For instance, in mouse embryos, apical tension is higher in the epiblast in comparison to other tissues and the difference is abolished in the absence of apical F-actin (Royer et al, 2022). The use of Flipper probes may expand our understanding of how mechanics tune cell signaling and cell fate during embryonic development and further developments of Flipper probes would allow an even more widespread use.