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Accueil du site > Animations Scientifiques > Séminaires 2012 > Ben Ovryn — Modeling and ultra-high resolution optical microscopy of the formation of nouveau adhesions
Ben Ovryn — Modeling and ultra-high resolution optical microscopy of the formation of nouveau adhesions
Speaker :
Ben Ovryn, Visiting Fellow at St Catherine’s College in Oxford and Associate Professor at the Gruss-Lipper Biophotonics Center, Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York www.ovrynlab.org
When :
Wednesday 14 March at 11h
Where :
Salle C023 (RDC LR6 côté Centre Blaise Pascal)
Title :
Modeling and ultra-high resolution optical microscopy of the formation of nouveau adhesions
Abstract :
Adhesion to an extracellular matrix (ECM), an essential process in cellular locomotion, requires interaction between adhesion receptors and their ligands. We have developed a model that provides a mechanistic understanding of the processes that govern the formation of the earliest integrin adhesions from an essentially planar plasma membrane. The model predicts that these ’’nouveau adhesions" can have radii less than 100 nm which is smaller than nascent adhesions that have been observed with conventional fluorescence microscopy. The model further predicts that polymerizing actin filaments must locally deform the membrane and translate an integrin’s extracellular binding domain toward the ECM. Without this active mechanism, longer molecules on the crowded membrane surface sterically inhibit the relatively short stalks of the conformationally activated heterodimer from reaching a ligand on the ECM.
In order to observe the formation of nouveau adhesions and actin dynamics at the ventral surface, we have developed a novel form of confocal interference microscopy and combined this method with simultaneous fluorescence microscopy. Using this approach, we have measured the membrane topography at focal adhesions and invadopodia in fixed and live cells. Furthermore, in order to improve the transverse spatial resolution, we have implemented a form of high-speed, single-molecule tracking based upon Photoactivated Localization Microscopy (PALM).
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