A biophysical trip: from organism to the single molecule
Invited by Hélène BOUVRAIS
New tools emerging from the field of physics allow direct observation of biological mechanisms yet limited to traditional approaches. Bringing together the traditional disciplines and the advanced physical tools helps to reconstitute and to study such complicated biological phenomena.
At the organism level, I have been studying the importance of the elastoviscoplastic properties of living materials for the process of tissue development. For this purpose, we first developed an instrument that is the scanning air puff tonometer, which is able to map point by point the viscoelastic properties of flat or gently curved soft materials in vivo. On the basis of the results obtained, the role of the gradients of elastoviscoplastic properties is outlined for the process of vascular tree formation. This is particularly important to bridge the gaps in the theory of tissue development and to highlight new possibilities for tissue engineering, based on a clarification of the role of physical features in developing biological material.
At the cell level, the first project aimed to understand how intercellular adhesion supported by cadherins is modulated according to the shape and size of cell-matrix adhesion (fibronectin-integrin). The coupling between cell-cell and cell-matrix adhesion systems is known to affect the stability of the adhesive status of cells, as well as tissue cohesion. We have been studying the micromechanical aspects of the crosstalk between cadherins and integrins. The second project aimed to study the homing of migrating cells from the circulating flow which is mediated by the interaction between selectins with glycoprotein ligands. We developed a real-time immunoprecipitation assay on a surface plasmon resonance chip that captures native glycoforms of two well-known E-selectin ligands (CD44/HCELL and PSGL-1) from hematopoietic cell extracts.
At the single-molecule level, techniques have evolved rapidly and already proven their novelty in studying the activity of a variety of individual enzymes. An important future direction for single molecule biophysics is the study of large protein complexes. Using a wide range of single-molecule and biochemistry techniques, I have been studying in particular 1) The branched actin biogenesis process using purified proteins (Actin, Arp2/3 complex and VCA), and 2) the DNA lagging stand replication using native and engineered purified proteins ( PCNA, Fen1, RFC, ...).
>>Monday, June 6 at 11:00 - IGDR conference room (ground floor of Building 4 / Villejean Campus)
Seminar in English, free entry subject to availability