TY - JOUR
T1 - Molecular determinants of magnesium-dependent synaptic plasticity at electrical synapses formed by connexin36
AU - Palacios-Prado, Nicolás
AU - Chapuis, Sandrine
AU - Panjkovich, Alejandro
AU - Fregeac, Julien
AU - Nagy, James I.
AU - Bukauskas, Feliksas F.
PY - 2014/8/19
Y1 - 2014/8/19
N2 - Neuronal gap junction (GJ) channels composed of connexin36 (Cx36) play an important role in neuronal synchronization and network dynamics. Here we show that Cx36-containing electrical synapses between inhibitory neurons of the thalamic reticular nucleus are bidirectionally modulated by changes in intracellular free magnesium concentration ([Mg 2+ ] i). Chimeragenesis demonstrates that the first extracellular loop of Cx36 contains a Mg 2+ -sensitive domain, and site-directed mutagenesis shows that the pore-lining residue D47 is critical in determining high Mg 2+ -sensitivity. Single-channel analysis of Mg 2+ -sensitive chimeras and mutants reveals that [Mg 2+ ] i controls the strength of electrical coupling mostly via gating mechanisms. In addition, asymmetric transjunctional [Mg 2+ ] i induces strong instantaneous rectification, providing a novel mechanism for electrical rectification in homotypic Cx36 GJs. We suggest that Mg 2+ -dependent synaptic plasticity of Cx36-containing electrical synapses could underlie neuronal circuit reconfiguration via changes in brain energy metabolism that affects neuronal levels of intracellular ATP and [Mg 2+ ] i.
AB - Neuronal gap junction (GJ) channels composed of connexin36 (Cx36) play an important role in neuronal synchronization and network dynamics. Here we show that Cx36-containing electrical synapses between inhibitory neurons of the thalamic reticular nucleus are bidirectionally modulated by changes in intracellular free magnesium concentration ([Mg 2+ ] i). Chimeragenesis demonstrates that the first extracellular loop of Cx36 contains a Mg 2+ -sensitive domain, and site-directed mutagenesis shows that the pore-lining residue D47 is critical in determining high Mg 2+ -sensitivity. Single-channel analysis of Mg 2+ -sensitive chimeras and mutants reveals that [Mg 2+ ] i controls the strength of electrical coupling mostly via gating mechanisms. In addition, asymmetric transjunctional [Mg 2+ ] i induces strong instantaneous rectification, providing a novel mechanism for electrical rectification in homotypic Cx36 GJs. We suggest that Mg 2+ -dependent synaptic plasticity of Cx36-containing electrical synapses could underlie neuronal circuit reconfiguration via changes in brain energy metabolism that affects neuronal levels of intracellular ATP and [Mg 2+ ] i.
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U2 - 10.1038/ncomms5667
DO - 10.1038/ncomms5667
M3 - Article
AN - SCOPUS:84907362937
VL - 5
JO - Nature Communications
JF - Nature Communications
SN - 2041-1723
M1 - 4667
ER -