Calcium Signaling in Neurogenesis and Neuron/Glial Cells Interactions
Our group is studying the interactions between neurons and glial cells which play a major role both in the development and the functioning of the central nervous system.
During neurogenesis, neuro-epithelial cells differenciate in neurons or in glial cells. The CNS is mainly constituted of glial cells such as radial glial cells, astrocytes or oligodendrocytes. These cells are involved in many physiological processes including neuron migration during development, the blood-brain barrier formation as well as the modulation of synaptic transmission and neural networks synchronization.
A dysfunction of these neural/glial interactions may be implied in some neurological disorders like epilepsy.
Since a few years, the expansion of functional cellular imaging technologies has revealed the spatio-temporal dynamic of the oscillations of intracellular calcium levels (calcium transients) in dorsal ectoderm and neural precursors.
Calcium transient and neuronal differenciation
Our group has greatly participated in the development of a multi-photon excitation microscopy platform (PIXEL) and a Biological resource centre dedicated to an amphibian animal model, the xenopus.
Based on the innovative technologies offered by these platforms (multiphotonic imaging, electrophysiology and transgenesis), we use the xenopus embryo to undertand how the electrical activity can modulate the development of the neural/glial network.
In this aim, we have obtained xenopus transgenic lines expressing the fluorescent protein eGFP under the control of neuron-specific (Neuro-bTubuline or NeuroD) or glial-specific (GFAP) promoters.
Embryos expressing a calcium probe derived form eGFP, G-CaMP (Nakai et al., 2001), with the same promoters are currently in preparation.This animals will be used for the functional imaging of calcium transients in neural or glial precursors during the development both in vitro and in vivo.
Epilepsy
In epilepsy, the normal physiological activity is interrupted by recurrent seizures in which abnormal synchronization processes affect certain groups of hyperactive neurons. The hippocampus, a part of the brain limbic system, is highly involved in the temporal lobe epilepsy. As a model of ictogenesis, we are using acute slices of rat hippocampus for which the architecture and neural networks functioning are well characterized.
The coupling between multi-photon imaging, electrophysiology, pharmacology and our close collaboration with a group studying human neural network modeling (F. WENDLING, INSERM U642) allow to progress in the understanding of the role of astrocytes in the epileptic seizure genesis.