Section: New Results

Quantifying the spatial distribution of intracellular events

Participant : Charles Kervrann.

Automated processing of fluorescence microscopy data allows to quantify cell phenotypes in an objective and reproducible way. However, most computational methods are based on the complex combination of heterogeneous features expressing geometrical, morphological and frequency properties, which makes difficult to draw definitive biological conclusions. Additionally, most experimental designs pool together data coming from replicated experiments of a given condition, neglecting the biological variability between individual cells. Hence, we developed a generic and nonparametric density framework (QuantEv) to discriminate spatiotemporal distributions (using circular Earth mover's distance) of moving proteins detected by any appropriate algorithm. The main advantage of QuantEv is to robustly process 2D and 3D data, and accurately analyse homogeneous and heterogeneous populations. As proof-of-principle, we first quantitatively characterized protein trafficking of Rab6 positive membranes between the Golgi apparatus and the plasma membrane. Next, we demonstrated that Rab11 positive membranes uniformly distribute around the Endosomal Recycling Compartment (ERC), regardless of the cell shape. Finally, we showed that actin organization is cell shape dependent, and evaluated its influence on the distribution of exocytosis/recycling vesicles. QuantEv is a flexible method which enables to quantify any intracellular trafficking in 3D flat or rounded, constrained or non-constrained, adherent or non-adherent cells.

References:  [36]

Collaborators: Thierry Pécot (Hollings Cancer Center, Medical Univ. South Carolina, Charleston, USA),

                          Jean Salamero, Jérôme Boulanger and Liu Zengzhen (UMR 144 CNRS-Institut Curie).