Cell polarity is essential for the development of organisms. Our lab uses the Nematode C. elegans to study the establishment and the maintenance of polarity in various cell types. The team was created in 2007 with an Avenir INSERM starting grant and is focused on the interplay between cellular and developmental biology.
- Epithelial polarity maintenance and membrane traffic
Epithelial cells rely on different intracellular trafficking pathways between the apical pole and the basolateral pole to achieve a polarised localisation of lipids and protein. Apical junctions act as a diffusion barrier separating the two poles. We study the role of the clathrin adaptor complex AP-1 in C. elegans epithelial cells. In C. elegans, as in Drosophila and mouse, the loss of AP-1 induces embryonic lethality. We recently found that AP-1 controls the apicobasal polarity in the C. elegans intestine and the apical localisation of CDC-42 and PAR-6 (Shafaq-Zadah et al., Development, 2012, 139:2061-70).
Genetic data also show that AP-1 has a repressor role during the basolateral targeting of the EGF receptor in vulval epithelial cells. We have identified new genes implicated in that process. (Holmes et al., in prep).
- Polarity in the early embryo
The establishment of a polarity axis is essential for asymmetric cell division. At the one-cell stage C. elegans embryo, the asymmetric localisation of the conserved PAR proteins defines the anteroposterior axis of the embryo. Following this polarisation the embryo divides asymmetrically, giving rise to two daughter cells which adopt different fates. We are investigating the mechanisms that control polarity establishment. In particular we study PAR protein degradation (Pacquelet et al., 2008) as well as the links between polarity and membrane traffic.