Tuesday 12 Nov 2019: Dynamics Seminar: Spatio-temporal control of cell dynamics
Doris Heinrich - Leiden Institute of Physics and Fraunhofer-Institut fuer Silicatforschung ISC
LSI Seminar Room A 13:30-15:30
A living cell is a complex out-of-equilibrium system, in which a great variety of biochemical and physical processes have to be coordinated to ensure viability. These exceptional dynamic properties are caused by the presence of ATP-driven motion. In particular, intracellular transport of cargos proceeds by successive phases of diffusion and active movement along microtubules via dynein and kinesin motors. While passive diffusion allows for intracellular transport of molecules on the nanoscale, it becomes inefficient for transport of large proteins, vesicles and organelles on the scale of a whole cell.
To distinguish these two intracellular transport processes, we developed a time-resolved identification method for motility state signatures of cytoplasmic tracers in living cells. A rolling-average algorithm is based on the analysis of the local mean-square displacement (MSD) and directional persistence of the tracer path to reliably separate the active and passive motion of particles in cells. This two-state motility model yields distributions for active and passive state durations, velocity during active phases and the diffusion coefficient of the passive motion, and further applicable to sub- and super-diffusive intracellular transport states.
This understanding of intracellular information- and material transport allows for control of cell functions by external cues. We investigate cell migration in spatio-temporally defined external boundary conditions and we analyse motion states of the entire cell, using an analogue method for dissecting into directed vs random migration states. Cell migrating on predefined 3D structured surfaces and in precisely monitored chemotactic gradients induces changes in cellular function and therefore controls cell migration.