New ion channel families
par- 6 mai 2010
Whole genomes sequencing has revealed the existence of numerous genes which functions are still unkwon. Our scientific goals articulate around the characterization of ion channels recently identified as such, but for which structural determinant, mode of activation or cellular functions have not yet been investigated. We have a special interest in calcium permeant ion channels expressed in the nervous system and immune cells. To tackle this work we use different approaches :
Structure-function studies : we use site directed mutagenesis to understand the molecular determinant of the channel function such as gating, permeation, stoechiometry… ;
Cellular functions and dynamic : because calcium permeant ion channel are involved in intracellular signalization and have important role in cell behavior, we use a proteomic approach to identify the signaling complex associated with these channels. This should lead to a better understanding of the intracellular pathways directly linked to these channels and help to decipher their cellular functions and dynamics. Cellular functions are also studied using RNAi technology
Physiological roles : we are also interested in understanding the role of these channels in integrated physiological functions. This is achieved through manipulation of gene expression such as knock-out or RNAi technologies.
We have focus our work on two ion channels families : purinergic P2X receptors which are ATP-gated channels, and TRP channel that are calcium-permeant channels gated by intracellular second messengers.
P2X receptors : we have identified several structural determinants of P2X receptors such as the pore region, ATP binding pocket and residus involved in the channel gating. We also have found a conserved motif that is responsible for the stabilization of P2X receptor complex at the plasma membrane. we are using proteomic to identify intracellular proteins associated with this motif and to get an insight of the cellular function of P2X receptors. In addition we have generated a P2X4 knock-out mice ; the role of this subunit in synaptic plasticity and inflammatory responses are currently studied.