cytoskeleton; actin; cell division; cell migration; blebs; active matter; non-equilibrium physics; collective phenomena; self-organization; phase fields; spontaneous waves
Stankevicins Luiza, Ecker Nicolas, Terriac Emmanuel, Maiuri Paolo, Schoppmeyer Rouven, Vargas Pablo, Lennon-Duménil Ana-Maria, Piel Matthieu, Qu Bin, Hoth Markus, Kruse Karsten, Lautenschläger Franziska (2020), Deterministic actin waves as generators of cell polarization cues, in Proceedings of the National Academy of Sciences
, 117(2), 826-835.
Levernier N, Kruse K (2020), Spontaneous formation of chaotic protrusions in a polymerizing active gel layer, in New Journal of Physics
, 22(1), 013003.
Klinkert Kerstin, Levernier Nicolas, Gross Peter, Gentili Christian, von Tobel Lukas, Pierron Marie, Busso Coralie, Herrman Sarah, Grill Stephan W, Kruse Karsten, Gönczy Pierre (2019), Aurora A depletion reveals centrosome-independent polarization mechanism in Caenorhabditis elegans, in eLife
, 8, e44552.
The cytoskeleton present in nearly all living cells is a network of linear polymers. It plays an essential role in vital cellular processes like division or migration and determines the mechanical properties of many cell types. The main components of the cytoskeleton are the proteins actin and tubulin, which assemble into actin filaments and microtubules, respectively. They interact with numerous proteins, notably molecular motors that convert chemical energy into mechanical work. From a physical point of view, the cytoskeleton belongs to the class of active matter, where energy is fed into the system at the level of its constituents. Physical studies of active gels have revealed phenomena that are unknown to equilibrium polymer networks. For example, active gels can spontaneously generate flows or topological point defects. Most theoretical studies of active gels have focused on static geometries. Moving or dividing cells, however, change their shapes due to cytoskeletal activity. We propose to study the interplay between the dynamics of active gels and of the domains they are confined to. We propose to use phase-field methods to account for changes in the domain shapes. Phase fields have successfully been used in studies of phase separation, crystallization, viscous fingering, fracture dynamics, etc. Recently, phase-field methods have also been introduced to study the dynamics of cellular shapes, notably in the context of cell migration. We plan to employ this tool to study three different topics. First, we want to continue our exploration of the role of spontaneous actin waves for cell motility. Second, we plan to study instabilities of the actin cortex -- a thin actin layer below the outer membrane of animal cells -- in particular in the context of cell division. Third, we want to apply these techniques to study blebs that appear, when cell membrane detaches from the actin network and bulges. We will solve the corresponding dynamic equations numerically on GPUs. Analytical work will be carried out in the sharp interface limit.We expect our studies to significantly advance our understanding of cellular shape regulation and to reveal further interesting phenomena unique to active matter. The techniques we will develop for the description and analysis of our systems will be useful also in other contexts, notably for investigating morphogenetic processes during embryonic development. In the context of cell migration, we expect to obtain new insights into behavioral consequences of actin-wave driven motility. Our studies on cell division should allow us to assess the role of dynamic instabilities for furrow formation and cell cleavage. The project part on blebs will be used to verify current conceptions about bleb formation and retraction.