How cells detect and respond to mechanical stimuli from their surroundings determines key processes in development, tumor formation and wound healing. However, while some molecules have been identified to possess mechanosensing capabilities, the molecular mechanical links by which cells withstand, transmit and detect forces remain unknown. In an analogy to the well-known concept of molecular biochemical pathways, we define this biophysical network of mechanical links as “molecular mechanical pathways”. We hypothesize that the molecules most likely to be directly experiencing forces applied from the extracellular matrix, which are the proteins that link extracellular matrix (ECM) receptors (integrins) to the actin cytoskeleton, are key components of these pathways. To our knowledge, only four such proteins, possessing binding sites to both integrins and actin, have been identified. These are talin, alpha-actinin, filamin, and tensin. I thus propose an interdisciplinary project aimed at identifying how talin, alpha-actinin, filamin, and tensin form the dynamic molecular pathways that communicate cells mechanically with their environment. In objective 1, a novel magnetic tweezers device and Atomic Force Microscopy will be employed study the role of these proteins in detecting, withstanding, and transmitting forces from the ECM. In objective 2 dynamic force protocols will be employed to determine the impact of real-life constantly changing cellular forces on these mechanical pathways. In objective 3, the molecular mechanisms behind these pathways will be elucidated by combining Fluorescence Resonance Energy Transfer (FRET) microscopy with AFM and observing how mechanical stimuli regulate protein stretching and binding. While the methods proposed and scientific questions addressed present important challenges, a robust interdisciplinary expertise in the techniques involved and a solid achievement record in the field support the feasibility of the project.
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