title: Quantitative methods for analyzing cell-cell adhesion in development.
abstract: During development cell-cell adhesion is not only crucial to maintain tissue morphogenesis and homeostasis, it also activates signalling pathways important for the regulation of different cellular processes including cell survival, gene expression, collective cell migration and differentiation. Importantly, gene mutations of adhesion receptors can cause developmental disorders and different diseases. Quantitative methods to measure cell adhesion are therefore necessary to understand how cells regulate cell-cell adhesion during development and how aberrations in cell-cell adhesion contribute to disease. Different in vitro adhesion assays have been developed in the past, but not all of them are suitable to study developmentally-related cell-cell adhesion processes, which usually requires working with low numbers of primary cells. In this review, we provide an overview of different in vitro techniques to study cell-cell adhesion during development, including a semi-quantitative cell flipping assay, and quantitative single-cell methods based on atomic force microscopy (AFM)-based single-cell force spectroscopy (SCFS) or dual micropipette aspiration (DPA). Furthermore, we review applications of Förster resonance energy transfer (FRET)-based molecular tension sensors to visualize intracellular mechanical forces acting on cell adhesion sites. Finally, we describe a recently introduced method to quantitate cell-generated forces directly in living tissues based on the deformation of oil microdroplets functionalized with adhesion receptor ligands. Together, these techniques provide a comprehensive toolbox to characterize different cell-cell adhesion phenomena during development.
authors.affiliation: Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. Electronic address: jubin.kashef@kit.edu.
authors.forename: Jubin
authors.initials: J
authors.lastname: Kashef
authors.affiliation: Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1a, 76131 Karlsruhe, Germany. Electronic address: clemens.franz@kit.edu.
authors.forename: Clemens M
authors.initials: CM
authors.lastname: Franz
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D018625:Microscopy, Atomic Force / Q000379:methods; D009024:Morphogenesis / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D059010:Single-Cell Analysis / Q000379:methods*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D015820:Cadherins
keywords: Atomic force microscopy (AFM)-based single-cell force spectroscopy (SCFS); Cadherin; Cell–cell adhesion; Dual micropipette aspiration (DPA); Flipping assay; Förster resonance energy transfer; Mechanical force