An official website of the United States government
Abstract Mechanical interactions between cells have been shown to play critical roles in regulating cell signaling and communications. However, the precise measurement of intercellular forces is still quite challenging, especially considering the complex environment at cell–cell junctions. In this study, we report a fluorescence lifetime‐based approach to image and quantify intercellular molecular tensions. Using this method, tensile forces among multiple ligand–receptor pairs can be measured simultaneously. We first validated our approach and developed lifetime measurement‐based DNA tension probes to image E‐cadherin‐mediated tension on epithelial cells. These probes were then further applied to quantify the correlations between E‐cadherin and N‐cadherin tensions during an epithelial–mesenchymal transition process. The modular design of these probes can potentially be used to study the mechanical features of various physiological and pathological processes.
more »
« less
Quantifying Tensile Forces at Cell–Cell Junctions with a DNA-based Fluorescent Probe
Cells are physically contacting with each other. Direct and precise quantification of forces at cell–cell junctions is still challenging. Herein, we have developed a DNA-based ratiometric fluorescent probe, termed DNAMeter, to quantify intercellular tensile forces. These lipid-modified DNAMeters can spontaneously anchor onto live cell membranes. The DNAMeter consists of two self-assembled DNA hairpins of different force tolerance. Once the intercellular tension exceeds the force tolerance to unfold a DNA hairpin, a specific fluorescence signal will be activated, which enables the real-time imaging and quantification of tensile forces. Using E-cadherin-modified DNAMeter as an example, we have demonstrated an approach to quantify, at the molecular level, the magnitude and distribution of E-cadherin tension among epithelial cells. Compatible with readily accessible fluorescence microscopes, these easy-to-use DNA tension probes can be broadly used to quantify mechanotransduction in collective cell behaviors.
more »
« less
- Award ID(s):
- 1662835
- PAR ID:
- 10179907
- Date Published:
- Journal Name:
- Chemical Science
- ISSN:
- 2041-6520
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Cells continuously experience and respond to different physical forces that are used to regulate their physiology and functions. Our ability to measure these mechanical cues is essential for understanding the bases of various mechanosensing and mechanotransduction processes. While multiple strategies have been developed to study mechanical forces within two-dimensional (2D) cell culture monolayers, the force measurement at cell-cell junctions in real three-dimensional (3D) cell models is still pretty rare. Considering that in real biological systems, cells are exposed to forces from 3D directions, measuring these molecular forces in their native environment is thus highly critical for the better understanding of different development and disease processes. We have recently developed a type of DNA-based molecular probe for measuring intercellular tensile forces in 2D cell models. Herein, we will report the further development and first-time usage of these molecular tension probes to visualize and detect mechanical forces within 3D spheroids and embryoid bodies (EBs). These probes can spontaneously anchor onto live cell membranes via the attached lipid moieties. By varying the concentrations of these DNA probes and their incubation time, we have first characterized the kinetics and efficiency of probe penetration and loading onto tumor spheroids and stem cell EBs of different sizes. After optimization, we have further imaged and measured E-cadherin-mediated forces in these 3D spheroids and EBs for the first time. Our results indicated that these DNA-based molecular tension probes can be used to study the spatiotemporal distributions of target mechanotransduction processes. These powerful imaging tools may be potentially applied to fill the gap between ongoing research of biomechanics in 2D systems and that in real 3D cell complexes.more » « less
-
null (Ed.)Cell adhesive force, exerting on the local matrix or neighboring cells, plays a critical role in regulating many cell functions and physiological processes. In the past four decades, significant efforts have been dedicated to cell adhesive force detection, visualization and quantification. A recent important methodological advancement in cell adhesive force visualization is to adopt force-to-fluorescence conversion instead of force-to-substrate strain conversion, thus greatly improving the sensitivity and resolution of force imaging. This review summarizes the recent development of force imaging techniques (collectively termed as cell adhesive force microscopy or CAFM here), with a particular focus on the improvement of CAFM’s spatial resolution and the biomaterial choices for constructing the tension sensors used in force visualization. This review also highlights the importance of DNA-based tension sensors in cell adhesive force imaging and the recent breakthrough in the development of super-resolution CAFM.more » « less
-
Green, Kathleen (Ed.)ABSTRACT This study investigated possible mechanisms underlying differences between heterophilic and homophilic cadherin adhesions that influence intercellular mechanics and multicellular organization. Results suggest that homophilic cadherin ligation selectively activates force transduction, such that resulting signaling and mechano-transduction amplitudes are independent of cadherin-binding affinities. Epithelial (E-) and neural (N-)cadherin cooperate with distinct growth factors to mechanically activate force transduction cascades. Prior results have demonstrated that E-cadherin and epidermal growth factor receptor form force-sensitive complexes at intercellular junctions. Here, we show that the reconstitution of N-cadherin force transduction requires the co-expression of N-cadherin and fibroblast growth factor receptor. Mechanical measurements further demonstrated that homophilic ligation initiates receptor tyrosine kinase-dependent force transduction cascades, but heterophilic cadherin ligands fail to activate signaling or generate stereotypical mechano-transduction signatures. The all-or-nothing contrast between mechano-transduction by heterophilic versus homophilic cadherin adhesions supersedes differences in cadherin adhesion strength. This mechano-selectivity impacts cell spreading and traction generation on cadherin substrates. Homophilic ligation appears to be a key that selectively unlocks cadherin mechano-transduction. These findings might reconcile the roles of cadherin recognition and cell mechanics in the organization of multicellular assemblies.more » « less
-
Shear forces between cells occur during global changes in multicellular organization during morphogenesis and tissue growth, yet how cells sense shear forces and propagate a response across a tissue is unknown. We found that applying exogenous shear at the midline of an epithelium induced a local, short-term deformation near the shear plane, and a long-term collective oscillatory movement across the epithelium that spread from the shear-plane and gradually dampened. Inhibiting actomyosin contraction or E-cadherin trans-cell adhesion blocked oscillations, whereas stabilizing actin filaments prolonged oscillations. Combining these data with a model of epithelium mechanics supports a mechanism involving the generation of a shear-induced mechanical event at the shear plane which is then relayed across the epithelium by actomyosin contraction linked through E-cadherin. This causes an imbalance of forces in the epithelium, which is gradually dissipated through oscillatory cell movements and actin filament turnover to restore the force balance across the epithelium.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D0SC01455A
