Neurocentre Magendie

Claire LEGER


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4 publication(s) depuis Novembre 2006:

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* equal contribution
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14/09/2011 | EMBO J   IF 9.6
Bidirectional integrative regulation of Cav1.2 calcium channel by microRNA miR-103: role in pain.
Favereaux A*, Thoumine O.*, Bouali-Benazzouz*, Roques V, Papon M.A., Abdel Salam S., Drutel G., Leger C, Calas A., Nagy F.*, Landry M.*

Chronic pain states are characterized by long-term sensitization of spinal cord neurons that relay nociceptive information to the brain. Among the mechanisms involved, up-regulation of Cav1.2-comprising L-type calcium channel (Cav1.2-LTC) in spinal dorsal horn have a crucial role in chronic neuropathic pain. Here, we address a mechanism of translational regulation of this calcium channel. Translational regulation by microRNAs is a key factor in the expression and function of eukaryotic genomes. Because perfect matching to target sequence is not required for inhibition, theoretically, microRNAs could regulate simultaneously multiple mRNAs. We show here that a single microRNA, miR-103, simultaneously regulates the expression of the three subunits forming Cav1.2-LTC in a novel integrative regulation. This regulation is bidirectional since knocking-down or over-expressing miR-103, respectively, up- or down-regulate the level of Cav1.2-LTC translation. Functionally, we show that miR-103 knockdown in naive rats results in hypersensitivity to pain. Moreover, we demonstrate that miR-103 is down-regulated in neuropathic animals and that miR-103 intrathecal applications successfully relieve pain, identifying miR-103 as a novel possible therapeutic target in neuropathic chronic pain.

20/01/2010 | J Neurosci   IF 5.9
Knockdown of L calcium channel subtypes: differential effects in neuropathic pain.
Fossat P*, Dobremez E*, Bouali-Benazzouz R, Favereaux A, Bertrand SS, Kilk K, Leger C, Cazalets JR, Langel U, Landry M, Nagy F


08/2007 | J Neurochem   IF 3.8
An intracellular motif of P2X(3) receptors is required for functional cross-talk with GABA(A) receptors in nociceptive DRG neurons
Toulme E, Blais D, Leger C, Landry M, Garret M, Seguela P, Boue-Grabot E

Functional cross-talk between structurally unrelated P2X ATP receptors and members of the 'cys-loop' receptor-channel superfamily represents a recently-discovered mechanism for rapid modulation of information processing. The extent and the mechanism of the inhibitory cross-talks between these two classes of ionotropic receptors remain poorly understood, however. Both ionic and molecular coupling were proposed to explain cross-inhibition between P2X subtypes and GABA(A) receptors, suggesting a P2X subunit-dependent mechanism. We show here that cross-inhibition between neuronal P2X(3) or P2X(2+3) and GABA(A) receptors does not depend on chloride and calcium ions. We identified an intracellular QST(386-388) motif in P2X(3) subunits which is required for the functional coupling with GABA(A) receptors. Moreover the cross-inhibition between native P2X(3) and GABA receptors in cultured rat dorsal root ganglia (DRG) neurons is abolished by infusion of a peptide containing the QST motif as well as by viral expression of the main intracellular loop of GABA(A)beta3 subunits. We provide evidence that P2X(3) and GABA(A) receptors are colocalized in the soma and central processes of nociceptive DRG neurons, suggesting that specific intracellular P2X(3)-GABA(A) subunit interactions underlie a pre-synaptic cross-talk that might contribute to the regulation of sensory synaptic transmission in the spinal cord.

20/11/2006 | J Comp Neurol   IF 3.3
Galanin receptor 1 is expressed in a subpopulation of glutamatergic interneurons in the dorsal horn of the rat spinal cord.
Landry M, Bouali-Benazzouz R, Andre C, Shi TJ, Leger C, Nagy F, Hokfelt T

The 29/30 amino acid neuropeptide galanin has been implicated in pain processing at the spinal level and local dorsal horn neurons expressing the Gal(1) receptor may play a critical role. In order to determine the transmitter identity of these neurons, we used immunohistochemistry and antibodies against the Gal(1) receptor and the three vesicular glutamate transporters (VGLUTs), as well as in situ hybridization, to explore a possible glutamatergic phenotype. Gal(1) protein, which could not be demonstrated in Gal(1) knockout mice, colocalized with VGLUT2 protein, but not with glutamate decarboxylase, in many nerve endings in lamina II. Moreover, Gal(1) and VGLUT2 transcripts were often found in the same cell bodies in laminae I-IV. Gal(1)-protein and galanin-peptide showed an overlapping distribution but were not colocalized. Gal(1) staining did not appear to be affected by dorsal rhizotomy. Taken together, these findings provide strong evidence that Gal(1) is a heteroreceptor expressed on excitatory glutamatergic dorsal horn interneurons. Activation of such Gal(1) receptors may thus decrease the inhibitory tone in the superficial dorsal horn, and possibly cause antinociception.