TY - JOUR TI - An in vitro DNA Sensor-based Assay to Measure Receptor-specific Adhesion Forces of Eukaryotic Cells and Pathogens AU - Wack, Maurizio AU - Wiegand , Tina AU - Frischknecht, Friedrich AU - Cavalcanti-Adam, E. Ada VL - 10 IS - 17 PY - 2020 DA - 2020/09/05 SP - e3733 C1 - Bio-protocol 2020;10:e3733 DO - 10.21769/BioProtoc.3733 UR - https://doi.org/10.21769/BioProtoc.3733 AB - Motility of eukaryotic cells or pathogens within tissues is mediated by the turnover of specific interactions with other cells or with the extracellular matrix. Biophysical characterization of these ligand-receptor adhesions helps to unravel the molecular mechanisms driving migration. Traction force microscopy or optical tweezers are typically used to measure the cellular forces exerted by cells on a substrate. However, the spatial resolution of traction force microscopy is limited to ~2 µm and performing experiments with optical traps is very time-consuming. Here we present the production of biomimetic surfaces that enable specific cell adhesion via synthetic ligands and at the same time monitor the transmitted forces by using molecular tension sensors. The ligands were coupled to double-stranded DNA probes with defined force thresholds for DNA unzipping. Receptor-mediated forces in the pN range are thereby semi-quantitatively converted into fluorescence signals, which can be detected by standard fluorescence microscopy at the resolution limit (~0.2 µm). The modular design of the assay allows to vary the presented ligands and the mechanical strength of the DNA probes, which provides a number of possibilities to probe the adhesion of different eukaryotic cell types and pathogens and is exemplified here with osteosarcoma cells and Plasmodium berghei Sporozoites. KW - Molecular force sensor KW - DNA-hairpin KW - Biomimetic surface KW - Receptor mediated forces KW - Molecular tension fluorescence microscopy KW - Plasmodium KW - Sporozoite JF - Bio-protocol SN - 2331-8325 PB - Bio-protocol LLC. BIO101 - False