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Dynamique de récepteurs uniques du GABAA dans le cône de croissance : rôle dans la détection de signaux de guidage

Abstract : During the development of the nervous system, extending axons choose accurately their
directions of growth. This step relies on the sensitive detection of guidance cues by receptors
in the membrane of the growth cone. We studied the dynamics of single GABA
receptors tagged by fluorescent nanocrystals. The receptors are initially homogeneously
distributed in the growth cone membrane and are specifically relocalized toward the source
when submitted to a GABA gradient. This reorganization is due to interactions with the
microtubules that have been identified by single receptor trajectory analysis and that displace
the receptors toward regions of high GABA concentration. The functional role of
this phenomenon has been revealed by the measurement of a receptor redistribution induced
an amplification in the asymmetry of calcium concentration. These results support
a model of receptor self-organization providing an amplification of the external signal. A
weak asymmetric activation of receptors causes a weak asymmetry of calcium concentration
and of the cytoskeleton organization. This creates a positive feedback loop by favoring
receptor redistribution that amplifies the gradient induced signal by enhancing the asymmetry
in the calcium concentration. The self-organization of the receptors can be correctly
described by a system of stochastic equations that has been analytically and numerically
studied. This study provides a general mechanism of amplification of external signals in
growing axons and also in chemotactic or polarized systems.
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https://tel.archives-ouvertes.fr/tel-00120620
Contributor : Cedric Bouzigues <>
Submitted on : Tuesday, December 19, 2006 - 8:46:27 AM
Last modification on : Monday, December 14, 2020 - 9:41:15 AM
Long-term archiving on: : Thursday, September 23, 2010 - 3:49:31 PM

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  • HAL Id : tel-00120620, version 3

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Cedric Bouzigues. Dynamique de récepteurs uniques du GABAA dans le cône de croissance : rôle dans la détection de signaux de guidage. Biophysique [physics.bio-ph]. Université Paris-Diderot - Paris VII, 2006. Français. ⟨tel-00120620v3⟩

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