A Force Spectroscopy Setup to Mimic Cellular Interaction Processes

Abstract

ment of a biophysical model system, which serves to quantify aspects of cell-virus (A), cell-cell (B), and cell-substrate (C) interactions.Moreover, controlled attachment and detachment regulate leukocyte binding to endothelium during inflammation processes. The key to cope with viral infections is to understand the reactions that take place at the first contact of cell and virus. Furthermore, the establishment of cell to substrate contacts is of crucial importance for the attachment of cells to connective tissue or the inclusion of rigid material like bone or cartilage into surrounding tissue. The Marfan syndrome for instance is characterized by a dysfunctionality of connective tissue resulting in aorta and skeleton malfunctions. [3] In these entire pathological processes vital cell signaling processes are influenced due to the lack or the occurrence of specific interactions between the cell and its periphery. Most relevant structures on cell surfaces are lectins, cadherins, and integrins as well as polysaccharide-bearing lipids.1 Schematic is not drawn to scale. All schematics are drawn by B. L. unless otherwise stated. rized by microvilli structures (A) enlarging the surface area available for the cells' uptake of nutrients. The lateral and basal membranes form borders to adjacent cells and the substrate, respectively. Tight junctions (B), adhesion junctions (C), desmosomes (D) and gap junctions (E) are functional units on the lateral membranes, whereas focal contacts (F) and hemidesmosomes (G) in the basal membrane are relevant for cellsubstrate interaction processes (H). Cytoskeletal components such as intermediated filaments (hemidesmosomes, desmosomes) and actin (adhesion junctions, focal contacts) are connected to these units. Gap junctions control the transport of small molecules, whereas tight junctions have a fence function. Tight junctions seal the intercellular space from the lumen of the tissue as they build barriers between the apical and the basolateral membranes of the cell. Gap junctions control the transport of small molecules between the cytosol of two adjacent cells, whereas the other structures shown on the lateral and the basal side of the cell act as mechanical transducers between the cells. Adherence junctions and focal contacts (basal cell membrane Figure 1.4-F) are coupled to actin filaments, whereas hemidesmosomes (basal membrane, Figure 1.4-G) 3 Image adapted from 6. 6. Wegener, J. (2001). Cell Junctions. eLS, John Wiley & Sons, Ltd.6 4 A list of abbreviations can be found in chapter 8.1 on page 126. 5 Image of Pietzsch, J., "The fluid-mosaic model of the cell membrane", nature.com, Nov 26, 2012, reprinted as a slightly modified version with permission of Nature Publishing Group. 6 Image is a snapshot taken from the video "The Inner Life of the Cell", Harvard Biovision, Leigh Stimolo, Alain Viel. glycero-3-phosphocholine (DPPC, B), 1,2-dioleyl-sn-glycero-3-phosphocholine (DOPC, C), or 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS, D) can be equipped with functionalized lipi...