- Institut de Génétique & Développement de Rennes; UMR 6290 CNRS - UR
Campus Santé de Villejean
2 avenue du Professeur Léon Bernard
Email : laurent [dot] chesneau [at] univ-rennes [dot] fr
Phone : +33 (0)2 23 23 48 85
Office number : bat4, 236
Current project: Intercellular junctions during cytokinesis
In 2022, I joined Roland Le Borgne's team which is interested in intercellular junctions during mitosis in epithelia using drosophila D. melanogaster as a model organism. Despite the rapid and massive morphological changes of cells in mitosis, the mechanical and permeability barrier of an epithelium is maintained, protecting the internal tissues from external attacks and preserving the integrity of the tissue. This requires a rearrangement of the acto-myosin cytoskeleton and of the various intercellular junctions (adherent and septal junctions) both at the bicellular and tricellular junctions of epithelial cells. I am currently investigating the role of intercellular junction components that are not canonical at adherens junctions.
Past projects (see Scientific background)
FIELDS OF INTEREST
Molecular and Cellular Biology with a particular interest for dynamical and polarized process.
From the generation of the genetic tool to image analysis via microscopy.
Generation of the genetic tool: crossing, transgenesis, clonal expression, RNA interference...
Fluorescence microscopy: confocal with conventional scanning or spinning-disc or Airyscan-type detector
Image analysis: morphological, colocalization, enrichment, speed measurement
Mitosis: from intracellular trafficking to intercellular junctions via the mitotic spindle
The question that has fascinated me for more than 20 years is how the cell organizes its internal structures spatially and dynamically during mitosis. During this phase of the cell cycle, which lasts from only a few minutes to a few tens of minutes, a cell changes its morphology by reorganizing all of its actin and microtubule cytoskeleton and its membrane compartments. During this time, the cell is able to segregate its genetic material, its organelles, its cytoplasm and the determinants of differentiation in the case of asymmetric division.
I began to address this problem during my thesis (2003-2007) carried out in Michel Jacquet's team, under the supervision of Marie-Hélène Cuif. In the yeast Saccharomyces cerevisiae, during the apical growth of the daughter cell, the actin cytoskeleton is oriented towards the tip of the young bud. The cytoskeleton is then rearranged to allow isotropic growth of the bud. This polarization of the cytoskeleton makes it possible, among other things, to direct a flow of secretory vesicles which bring the membrane receptors as well as the enzymes necessary for the synthesis of the cell wall. We have characterized the role of two regulators of the Rab GTPase Sec4p, Gyp5p and Gyl1p, two GTPase Activating Proteins (GAP) to polarize vesicle secretion during apical bud growth.
I continued the study of Rab GAP during mitosis, but this time in HeLa cells and at the last stage of mitosis: cytokinesis. My post-doctorate began in the team of Arnaud Echard, in the laboratory of Buno Goud at the Institut Curie (2007-2010) before following Arnaud at the Institut Pasteur (2010-2011). During this period, I uncovered an endocytosis regulatory pathway between the GTPase Arf6, the RabGAP Epi64 and the GTPase Rab35.
I continued to explore the mechanisms of intracellular organization during mitosis by focusing on the positioning of the mitotic spindle and the influence of kinetochore-microtubule attachments on the dynamics of the mitotic spindle, in the one-cell embryo of the nematode C. elegans. I participated in this research (2011-2022) in the team of Jacques Pécréaux at the IGDR after having been recruited there as a study engineer. In particular, with Ruddi Rodriguez-Garcia, we characterized the dynamics of recruitment to the cortex of dynein, the molecular motor responsible for the pulling forces on the astral microtubules and thus the posterior displacement of the spindle. The study of the residence time in the cortex of dynein showed that its enrichment in the posterior cortex is not due to a lengthening of its residence time but to a higher number of recruitment sites. Within the framework of studies on the dynamics of the spindle, measured by following the spindle length on the scale of the second, I continued the characterization (initiated by Xavier Pinson) of the effect of the transient inactivation of AuroraB and i have developed a model for studying the spindle in the context of tetraploid cells. I also co-supervised Nina Soler during her thesis on the dynamics of spindle microtubules.