Mechanical signals play a critical role in regulating physiological and pathological processes like tissue formation and maintenance, stem cell differentiation and cancer metastasis. However, the molecular mechanisms by which mechanical forces induce biological responses are largely unknown. This is primarily due to the lack of automated, high throughput, high resolution, techniques to explore the relationship between mechanical force, molecular structure and physiological function. The first goal of this proposal is to develop an ultra-stable, automated, microscope that can measure interaction forces between single molecules while simultaneously monitoring their conformation. This instrument, called the Microscope for Ultrasensitive-measurement of Single- molecule Interaction and Conformation (MUSIC), will integrate an ultra-stable atomic force microscope (AFM) with fluorescence resonance energy transfer (FRET). As described in our preliminary data, we have already developed prototype technologies for ultra-stable AFM operation and for integrating single molecule FRET and AFM methods.
The second aim of our proposal is to use MUSIC to determine the biophysical basis by which E- cadherin, an essential cell-cell adhesion protein that mediates the integrity of all soft tissue, responds to mechanical force. Based on extensive preliminary data, we hypothesize that E-cadherins bind in multiple conformations and modulate adhesion by switching between these structures. However, the mechanisms by which different E-cadherin structures are formed is unknown and direct evidence for their interconversion is lacking. MUSIC will be used to map out the different adhesive conformations adopted by E-cadherin, measure their force-induced interconversion and to assign a mechanistic role to individual protein domains in E-cadherin adhesion. The results of this research will provide a biophysical understanding of how cells interact, attach, detach and metastasize.
Mechanical signals play critical roles in regulating several physiological and pathological processes such as cancer metastasis, stem cell differentiation and tissue remodeling. However, due to the absence of suitable measurement techniques, the molecular mechanisms by which mechanical force exerts a biological effect is unknown. The goals of this proposal are to develop the world?s first automated microscope that can correlate the effects of mechanical stimulus on the conformation of single molecules and to use this instrument to determine the biophysical basis by which E-cadherin, an essential cell-cell adhesion protein, responds to mechanical force.
|Shafraz, Omer; Rübsam, Matthias; Stahley, Sara N et al. (2018) E-cadherin binds to desmoglein to facilitate desmosome assembly. Elife 7:|
|Schmidt, Patrick D; Reichert, Benjamin H; Lajoie, John G et al. (2018) Method for high frequency tracking and sub-nm sample stabilization in single molecule fluorescence microscopy. Sci Rep 8:13912|
|Yen, Chi-Fu; Sivasankar, Sanjeevi (2018) Improving estimation of kinetic parameters in dynamic force spectroscopy using cluster analysis. J Chem Phys 148:123301|
|Yen, Chi-Fu; Sivasankar, Sanjeevi (2017) Minimizing open-loop piezoactuator nonlinearity artifacts in atomic force microscope measurements. J Vac Sci Technol B Nanotechnol Microelectron 35:053201|