Identification and super-resolution imaging of ligand-activated receptor dimers in live cells

Pascale Winckler (1) , Lydia Lartigue (2) , Gregory Giannone (3) , Francesca de Giorgi (4) , François Ichas (4) , Jean-Baptiste Sibarita (3) , Brahim Lounis (5) , Laurent Cognet (5)

1 LP2N - Laboratoire Photonique, Numérique et Nanosciences
2 Plateforme de génétique moléculaire des cancers d'Aquitaine
3 IINS - Interdisciplinary Institute for Neuroscience [Bordeaux]
4 Fluofarma
5 lp2n-04,lp2n-12

Molecular interactions are key to many chemical and biological processes like protein function. In many signaling processes they occur in sub-cellular areas displaying nanoscale organizations and involving molecular assemblies. The nanometric dimensions and the dynamic nature of the interactions make their investigations complex in live cells. While super-resolution fluorescence microscopies offer live-cell molecular imaging with sub-wavelength resolutions, they lack specificity for distinguishing interacting molecule populations. Here we combine super-resolution microscopy and single-molecule Förster Resonance Energy Transfer (FRET) to identify dimers of receptors induced by ligand binding and provide super-resolved images of their membrane distribution in live cells. By developing a two-color universal-Point-Accumulation-In-the-Nanoscale-Topography (uPAINT) method, dimers of epidermal growth factor receptors (EGFR) activated by EGF are studied at ultra-high densities, revealing preferential cell-edge sub-localization. This methodology which is specifically devoted to the study of molecules in interaction, may find other applications in biological systems where understanding of molecular organization is crucial.

Domaines: Biophysique [physics.bio-ph]

Pascale Winckler, Lydia Lartigue, Gregory Giannone, Francesca de Giorgi, François Ichas, et al.. Identification and super-resolution imaging of ligand-activated receptor dimers in live cells. Scientific Reports, 2013, 3, pp.2387. ⟨10.1038/srep02387⟩. ⟨hal-00909281⟩