Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 6: Poster I

BP 6.42: Poster

Montag, 1. April 2019, 17:30–19:30, Poster B2

Traction Force Microscopy during Phagocytosis — •Wolfgang Groß and Holger Kress — Biological Physics Group, Department of Physics, University of Bayreuth, Bayreuth, Germany

In the process of phagocytosis, cells internalize objects like bacteria and dead cells that have a size of several micrometers, thus being a main function of innate immunity. After the detection of foreign particles, the membrane starts to wrap around the phagocytic target. This so-called phagocytic cup is mechanically supported by the polymerization of actin filaments in combination with myosin motors. Even though the main molecular players have been identified already, there is only few quantitative data describing the dynamics of the major regulators.

To investigate the uptake dynamics we use immunoglobulin G (IgG) coated polystyrene particles with a diameter of 10 micrometers as a model system. Using a combination of traction force microscopy (TFM) and holographic optical tweezers, we are able to measure cellular forces during phagocytosis in a spatially and temporally resolved manner. As a substrate, we use soft polyacrylamide films with a thickness of a few tens of micrometres which we coat with fibronectin to mediate cell adhesion. TFM allowed us to quantify the forces, which J774 macrophages exert during adhesion and phagocytic uptake. Preliminary data show the distribution of contractile forces in the direct vicinity of the phagocytic target. We anticipate our results to pave the way for a more quantitative understanding of phagocytosis and thus, enable the development of new models for this process.