Spatiotemporal feedback between cytoskeletal mechanics and signaling

We are interested in the physical principles underlying the self-organization of cells’ cytoskeleton and its biochemical regulators. Specifically, we wish to relate self-organized patterns observed in specific biological processes, such as wound healing or cell polarization, to specific mechanisms of spatio-temporal feedback between cytoskeletal mechanics and the reaction kinetics of regulators. We make this relation by developing hydrodynamic theories based on non-equilibrium thermodynamics. By comparing theory and experiments, we can therefore clarify the self-organizing principles at the base of specific biological processes. [Figure from Fritz et al, Science Signaling (2013)]

With Olivier Pertz, Damien Brunner, Daniel Riveline and Karsten Kruse

Helical tubes of lipid membranes

ESCRT-III polymers are responsible for membrane remodeling in many cellular processes, ranging from the maturation of retroviruses (like HIV and Ebola) to the constriction of the cytokinetic bridge. Despite its ubiquitous biological role, many aspects of ESCRT-mediated membrane remodeling are still unclear. Recent in vitro experiments revealed that ESCRT polymers can reshape spherical vesicles into helical tubes. Inspired by structural insights from such experiments, we develop generic theories on the competition between ESCRT and membrane elasticity to shed light on the ESCRT-membrane interactions responsible of membrane remodeling in vivo. [Left panel from Moser Von Filseck et al, Nature Communications (2020). Right panel from my PhD thesis.]

With Joachim Moser Von Filseck, Aurélien Roux and Martin Lenz

Inter-helical forces and geometry in DNA toroids

In viruses and cells, DNA is closely packed and tightly curved thanks to polyvalent cations inducing an effective attraction between its negatively charged filaments. Our understanding of this effective attraction remains very incomplete, mainly because it results from multiple microscopic mechanisms that are hard to predict starting from first principles. We study this fundamental attraction by combining structural data of DNA condensates realized in vitro with effective equilibrium theories, where inter-helical forces compete with DNA elasticity. [Figure is adapted from Barberi et al, BioRxiv (2020)]

With Amélie Leforestier, Françoise Livolant and Martin Lenz