1- Control of Hox induced morphogenesis:

We have established the study of the external respiratory organs of the Drosophila larva, the posterior spiracles, as a model to analyse how selector genes specify the cells and change their behaviours during organogenesis. We have shown that during spiracle formation, the Hox transcription factor ABD-B activates a unique transcriptional cascade in the eighth abdominal segment that induces the cells to change cell shape and rearrange their relative positions leading to the invagination of the posterior spiracles. We have found that the targets of this Hox transcriptional cascade include apico-basal cell polarity genes, cadherins and GAP and GEF regulators of the small GTPase Rho which control the actin cytoskeleton in the spiracle. We are currently analysing how of all these fundamental proteins are co-ordinately modulated to induce the characteristic elongation and rearrangement cell behaviours of the developing spiracles.

 

2- Study of the Drosophila JAK/STAT signalling function during development:

Work in our laboratory has contributed to demonstrate that the Drosophila JAK/STAT pathway is a streamlined version of the vertebrate pathway. We are using this simpler model to understand how the cytokine ligands are transmitted between cells, how the receptor is activated and how STAT activates its downstream targets. We are currently analysing how the pathway signal transduction proteins are compartmentalised in the epithelial cell to signal efficiently in highly polarised tissues.