et Systèmes Complexes"
20 juin 2005 à 11h30
couloir 33-43, 2ème étage, salle de réunion
Jean Louis Bessereau
de la synaptogenèse dans un système simple, le nématode C. elegans.
Chemical synapses are
specialized sites of cell contact capable of relaying information from
one cell to another quickly and with high fidelity. These biophysical
properties are due, in part, to the spatial relationships between the
synaptic vesicle exocytosis machinery and the postsynaptic
neurotransmitter-sensing apparatus. We are using the simple model
organism C. elegans which only contains 302 neurons to
characterize the precise spatial organization of the synapse in the
living state and to identify novel genes and mechanisms involved in
High-pressure freezing of a living animal combined with morphological
and immuno-electron microscopy provides a mean to catch the synapse in
suspended animation. By quantitative analysis of pre- and post-synaptic
proteins distribution, we established a functional topomap of the
synapse at electron microscopy resolution. It reveals a striking
match between the area of synaptic vesicles release and the
distribution of post-synaptic receptors.
components of the receptor clustering machinery, we conducted genetic
screens. Specifically, we cloned the gene lev-10, which encodes
a novel transmembrane protein required for acetylcholine receptor
clustering (AChR). The ectodomain of LEV-10 is sufficient to achieve
AChR aggregation in vivo, thus suggesting a novel mechanism for
AChR clustering relying on extracellular protein interactions.