Controlled cell-cell interactions play a crucial role in many biological events. Some processes like embryonic development and tumor metastasis rely on these short-lived extremely weak recognition events, which demand many parallel but rather weak and thus reversible bonds but still highly specific interaction. The ultra-weak carbohydrate-carbohydrate interactions (CCIs) between glycosphingolipids provide the required adhesion force and high specificity. Here, we employ analytical methods based on atomic force microscopy (AFM) to investigate two very weak interactions, one relying on the homophilic Lewis X – Lewis X recognition and the other one between the ganglioside GM3 and the cerebroside LacCer. By combining single cell experiments and model membrane studies we were able to quantify not only the involved forces but also the extract the thermodynamics of the weak interaction between two sugar moieties.<br/>For single cell experiments B16-F1 and B16-F10 tumor cell lines displaying different malignancy were used to investigate cell attachment by means of single-cell force spectroscopy (SCFS). A single cell is attached to a Poly-D-lysine coated cantilever and brought into contact with a LacCer containing solid supported lipid membrane (SLM). The recorded force-distance curves here deliver a direct measure of the interaction forces and adhesion energies between the GM3 overexpressing cells and the LacCer containing SLM.<br/>Cell experiments are complemented by model membrane studies employing colloidal probe microscopy (CPM). Here, the interactions between LacCer containing SLMs and a silicate sphere coated with a GM3 containing membrane are probed. These experiments provide a direct measure of the binding affinity between the carbohydrate moieties and its dependency on the cell membrane composition and lateral bilayer organization.

Quantification of weak and ultraweak carbohydrate-carbohydrate interactions in cellular recognition

2019 Spring National Meeting

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