Abstract of Dr Philippe ROSAY's thesis
Introduction
When the mosquito aedes aegypti stings, it secrets two peptides within its saliva. These are tachykinins, and lead to a vasodilatation. They seem to use tachykinins receptors of the host. Apart for this case, which can be opportunistic, the function of the tachykinins and their receptors are far from being understood, at least in invertebrates. That's why we worked on a receptor, NKD, in Drosophila. One interesting feature of NKD is its expression. Surprisingly, NKD expression starts 1 h after the beginning of neuroblasts segregation and is may be involved in neurogenesis or development. Evidences exist of NKD regulation by the proneural gene atonal. This page explains NKD involvement in PNS elaboration as ectopic expression of NKD and transdominant negative mutant suggest.
Tachykinins
Tachykinins were isolated from different species and take
place in sensory transmission, inflammation process or cellular
proliferation. They are expressed in digestive and nervous systems,
with an opposite role from opioids. No tachykinins are known in
Drosophila, but receptors exist.
We characterised one of them, NKD (for Drosophila
neuropeptide receptor), coupled to phospholipase
C.
The G-protein-coupled-receptors' structure
Tachykinins receptors belong to the large family of GPCR (G-protein-coupled-receptors
). Their snake-like structure
consists of 7 transmembrane domains, sites for ligand binding
and for coupling to G proteins.
Signal transduction
NKD is coupled to the phospholipase C by Gq and may be involved
in the ras/MAPKinase pathway. Depending on its expression location
and timing, a receptor can act on different signal transduction
pathways.