TY - JOUR A1 - Hsu, H. F. A1 - Krekhov, Andrey A1 - Tarantola, Marco A1 - Beta, Carsten A1 - Bodenschatz, Eberhardt T1 - Interplay between myosin II and actin dynamics in chemotactic amoeba JF - New journal of physics : the open-access journal for physics N2 - The actin cytoskeleton and its response to external chemical stimuli is fundamental to the mechano-biology of eukaryotic cells and their functions. One of the key players that governs the dynamics of the actin network is the motor protein myosin II. Based on a phase space embedding we have identified from experiments three phases in the cytoskeletal dynamics of starved Dictyostelium discoideum in response to a precisely controlled chemotactic stimulation. In the first two phases the dynamics of actin and myosin II in the cortex is uncoupled, while in the third phase the time scale for the recovery of cortical actin is determined by the myosin II dynamics. We report a theoretical model that captures the experimental observations quantitatively. The model predicts an increase in the optimal response time of actin with decreasing myosin II-actin coupling strength highlighting the role of myosin II in the robust control of cell contraction. KW - actin KW - myosin II KW - chemotaxis KW - oscillations KW - coupling KW - delay differential equation KW - contraction Y1 - 2019 U6 - https://doi.org/10.1088/1367-2630/ab5822 SN - 1367-2630 VL - 21 IS - 11 PB - IOP Publ. Ltd. CY - Bristol ER - TY - GEN A1 - Barbosa Pfannes, Eva Katharina A1 - Anielski, Alexander A1 - Gerhardt, Matthias A1 - Beta, Carsten T1 - Intracellular photoactivation of caged cGMP induces myosin II and actin responses in motile cells N2 - Cyclic GMP (cGMP) is a ubiquitous second messenger in eukaryotic cells. It is assumed to regulate the association of myosin II with the cytoskeleton of motile cells. When cells of the social amoeba Dictyostelium discoideum are exposed to chemoattractants or to increased osmotic stress, intracellular cGMP levels rise, preceding the accumulation of myosin II in the cell cortex. To directly investigate the impact of intracellular cGMP on cytoskeletal dynamics in a living cell, we released cGMP inside the cell by laser-induced photo-cleavage of a caged precursor. With this approach, we could directly show in a live cell experiment that an increase in intracellular cGMP indeed induces myosin II to accumulate in the cortex. Unexpectedly, we observed for the first time that also the amount of filamentous actin in the cell cortex increases upon a rise in the cGMP concentration, independently of cAMP receptor activation and signaling. We discuss our results in the light of recent work on the cGMP signaling pathway and suggest possible links between cGMP signaling and the actin system. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 239 KW - cyclic-gmp KW - dictyostelium-discoideum KW - ena/vasp proteins KW - osmotic-stress KW - chemotaxis KW - phosphorylation KW - amp KW - cytoskeleton KW - oscillations KW - chemoattractant Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-94984 SP - 1456 EP - 1463 ER - TY - GEN A1 - Alonso, Sergio A1 - Stange, Maike A1 - Beta, Carsten T1 - Modeling random crawling, membrane deformation and intracellular polarity of motile amoeboid cells T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - Amoeboid movement is one of the most widespread forms of cell motility that plays a key role in numerous biological contexts. While many aspects of this process are well investigated, the large cell-to-cell variability in the motile characteristics of an otherwise uniform population remains an open question that was largely ignored by previous models. In this article, we present a mathematical model of amoeboid motility that combines noisy bistable kinetics with a dynamic phase field for the cell shape. To capture cell-to-cell variability, we introduce a single parameter for tuning the balance between polarity formation and intracellular noise. We compare numerical simulations of our model to experiments with the social amoeba Dictyostelium discoideum. Despite the simple structure of our model, we found close agreement with the experimental results for the center-of-mass motion as well as for the evolution of the cell shape and the overall intracellular patterns. We thus conjecture that the building blocks of our model capture essential features of amoeboid motility and may serve as a starting point for more detailed descriptions of cell motion in chemical gradients and confined environments. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1014 KW - signaling system KW - eukaryotic chemotaxis KW - Dictyostelium cells KW - actin cytoskeleton KW - excitable networks KW - PIP3 waves KW - migration KW - dynamics KW - oscillations KW - transduction Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459745 SN - 1866-8372 IS - 1014 ER -