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Animal cells

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    Cellular motion of fibroblast cells

    Our work on animal cells has a strong focus on mouse embryonic fibroblasts. We are interested in the motility and active deformations of these cells and especially in the mechanisms that lead to the various different forms of cellular motion that are based on the polymerization of actin. One of our special interests thereby lies in the widely observed wave-like phenomena. We study the dynamics of cell morphology in great details using advanced methods of digital image processing.

In their natural environment, fibroblast cells are adherently growing in an extracellular matrix to which they specifically bind by adhesion molecules. The spreading of cells on substrates can be studied in vitro by mimicking the extracellular matrix using cover slides that are coated with extracellular matrix molecules. During the spreading process cells undergo a dramatic change in morphology which is caused by an interplay of actin polymerization, membrane adhesion and membrane mechanics. 

We are interested in the mechanisms behind the numerous different forms of cellular motion that are observed during the spreading process, ranging from uniform protrusion to wave phenomena. We study the dynamics of morphology during cell spreading by use of contact-area-sensitive microscopy techniques like total internal reflection fluorescence microscopy and reflection interference contrast microscopy that provide high resolution imaging data.

Cells have the ability to deform their plasma membrane to internalize extracellular matter. There are various different processes of that kind ranging from macropinocytosis over phagocytosis to invadopodia. Dorsal ruffling refers to a cell deformation on the dorsal side of adherent cells that resembles the class of endocytotic deformations. The biological role of dorsal ruffling is still debated, but it is known that the driving force leading to membrane deformation is actin polymerization.

We are interested in the mechanisms that control the actin dynamics in dorsal ruffling. Recent research highlights the potential role of curved membrane proteins that are actin factors. Such proteins provide a coupling between the local membrane geometry and actin dynamics. We therefore study the three-dimensional membrane topology in conjunction with protein densities in detail. We further aim for the understanding of the role played by membrane mechanics and spontaneous curvature in dorsal ruffling.