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Accueil > Pages personnelles > Aurélie Dupont

Research

par Aurelie - publié le , mis à jour le

Mechanical signal processing at the cell scale


Mechanical signal processing at the cell scale : experimental approach

Cells can sense the physical properties of their environment through a mechanism called mechanotransduction and accordingly modulate essential functions such as motility, adhesion or differentiation. Molecular interactions are now well described, showing very complex networks, however the coordination in space and time of mechanical and biochemical signals is not yet clear. The main goal is to understand this mechano-chemical coupling at the scale of an individual cell with an experimental approach. In order to be able to mechanically stimulate a living cell and simultaneously read its biochemical response, with a good spatio-temporal resolution (1µm , 0.1s), we have developed innovative methods : a quantitative method for measuring FRET-based biosensors and unique activable substrates. On-going work aims at measuring the spatio-temporal response function of key signaling proteins after a defined mechanical perturbation. The ultimate goal is to understand how cells process information, especially mechanical information.


Quantitative FRET imaging and analysis :

The QuanTI-FRET method applied to FRET standards

One challenge of this project was to be able to measure the biochemical activity of a target protein in a living cell in a spatially and temporally resolved manner. This is not possible with classical molecular biology methods, however, new tools have recently emerged, namely fluorescent biosensors. Most of them are based on the principle of "Förster Resonance Energy Transfer" (FRET), i.e. the transfer of energy between two fluorophores allowing to probe distances of the order of a few nanometers and thus changes in protein conformation. These biosensors have enormous potential but their development is hampered on the one hand by the difficulty to develop them and on the other hand by the difficulty of measuring FRET reliably in living cells. To unblock this last point, we developed a new method for measuring and quantitatively analysing FRET during Alexis Coullomb’s thesis, in collaboration with the teams of Don Lamb (LMU Munich) and Corinne Albigès-Rizo (IAB Grenoble). Starting again from the physical equations of fluorescence signal acquisition, we have refreshed the theoretical framework and proposed a new calibration method that allows the measurement of absolute FRET values and thus opening the way to new experiments, beyond the framework of mechanotransduction.

  • "QuanTI-FRET : a framework for quantitative FRET measurements in living cells". Alexis Coullomb, Cécile M Bidan, Chen Qian, Fabian Wehnekamp, Christiane Oddou, Corinne Albigès-Rizo, Don C Lamb, Aurélie Dupont. Scientific Reports 10 (1), 1-11 (2020)


Magneto-active substrates :

Magneto-active substrates : stimulation of living fibroblasts with concomitant force measurement.

The experimental objective was to impose a mechanical stress on the scale of a single cell in a local and dynamic way while trying to remain as physiological as possible, i.e. via a continuous substrate. To meet these specifications, we therefore invented a new experimental device : magneto-active substrates. In collaboration with Martial Balland (MicroTiss team) and Nora Dempsey (Institut Néel, Grenoble), Cécile Bidan (post-doc) succeeded in making a deformable substrate on which cells can adhere. It consists of magnetic inclusions, iron micro-pillars, in a thin layer of elastomer (PDMS). With a pair of electromagnets, we can apply a mechanical stress to the cells via their adhesions and also measure the traction forces exerted by the cells.

  • "Magneto-active substrates for local mechanical stimulation of living cells". Cécile M Bidan, Mario Fratzl, Alexis Coullomb, Philippe Moreau, Alain H Lombard, Irène Wang, Martial Balland, Thomas Boudou, Nora M Dempsey, Thibaut Devillers, Aurélie Dupont. Scientific Reports 8 (1), 1-13 (2018)


New project at the macroscopic scale


A new project is starting with a colleague from another LIPhy team (MOVE), Philippe Peyla (numerical simulation and theory in fluid mechanics). We are going to observe the collective behaviour of schools of fish in response to different physical constraints : solid obstacles or hydrodynamic constraints. This project is in the continuity of my questioning on the interaction of living organisms with their physical environment but, of course, on a very different scale.



Collaborations


  • Nora Dempsey et Thibaut Devillers, Institut Néel, Grenoble
  • Corinne Albigès-Rizo et Olivier Destaing, IAB, Grenoble
  • Martial Balland, Thomas Boudou, LIPhy, Grenoble
  • Alice Nicolas, LTM, Grenoble
  • Uwe Schlattner, LBFA, Grenoble
  • Don C Lamb, LMU, Munich
  • Joachim Rädler, LMU, Munich
  • Erwin Frey, LMU, Munich



Current group


  • Alain Lombard, graduate student 2017-2020
  • Ali Reda, trainee, M2 Nanobio UGA, supervised with Alice Nicolas, LTM, Grenoble
  • Renaud Larrieu, trainee, M2 physics UGA, supervised with Philippe Peyla, team MOVE, LIPhy

    Alumni


  • Cécile Bidan : postdoc 2014-2017, now junior group leader MPI Potsdam, Germany
  • Alexis Coullomb : doctorant 2015-2018, now postdoc in Toulouse
  • Sadequa Sultana : postdoc 2017