03.07.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Piconewton-sensitive biosensors to investigate molecular forces in cells

Abstract: The ability of cells to adhere and simultaneously sense differences in tissue stiffness is crucial for organ development and function. Yet, the molecular mechanisms by which cells sense extracellular matrix rigidity have remained unknown because suitable techniques to measure mechanical forces across intracellular proteins in living cells were missing.

We therefore develop novel, single-molecule‒calibrated tension sensor modules that allow the analysis of a physiologically highly relevant force regime in cells. Our new probes are sensitive to forces of 3–5 piconewton (pN), 6–8 pN and 9–11 pN, respectively; they are characterized by fast folding/unfolding transitions, reversibility and a sharp force-response threshold (1, 2, 3). By applying these new probes to the cell adhesion proteins talin-1 and talin-2, we demonstrate that these central integrin activators establish intracellular, mechanical linkages that bear mechanical forces of about 7–10 pN upon cell adhesion and are regulated by f-actin and vinculin association. We find that the integrin–talin–actin linkage is indispensable for extracellular rigidity sensing and, surprisingly, talin isoform-specific (1). Furthermore, multiplexing distinct tension sensor constructs by dual-color FLIM reveals an unexpected intramolecular tension gradient across talin that is modulated by intracellular signals and extracellular rigidity (3).

References:

1. Austen KA et al., and Grashoff C. 2015. Nat Cell Biol.

2. Freikamp A, Cost AL, and Grashoff C. 2016. Trends Cell Biol.

3. Ringer et al., and Grashoff C. 2017. under review

Prof. Christine Selhuber-Unkel

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