Activity-dependent ubiquitination of GABA(A) receptors regulates their accumulation at synaptic sites.
GABA(A) receptors (GABA(A)Rs) are the major mediators of fast synaptic inhibition in the brain. In neurons, these receptors undergo significant rates of endocytosis and exocytosis, processes that regulate both their accumulation at synaptic sites and the efficacy of synaptic inhibition. Here we have evaluated the role that neuronal activity plays in regulating the residence time of GABA(A)Rs on the plasma membrane and their targeting to synapses. Chronic blockade of neuronal activity dramatically increases the level of the GABA(A)R ubiquitination, decreasing their cell surface stability via a mechanism dependent on the activity of the proteasome. Coincident with this loss of cell surface expression levels, TTX treatment reduced both the amplitude and frequency of miniature inhibitory synaptic currents. Conversely, increasing the level of neuronal activity decreases GABA(A)R ubiquitination enhancing their stability on the plasma membrane. Activity-dependent ubiquitination primarily acts to reduce GABA(A)R stability within the endoplasmic reticulum and, thereby, their insertion into the plasma membrane and subsequent accumulation at synaptic sites. Thus, activity-dependent ubiquitination of GABA(A)Rs and their subsequent proteasomal degradation may represent a potent mechanism to regulate the efficacy of synaptic inhibition and may also contribute to homeostatic synaptic plasticity.
Saliba
Richard S
RS
Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Michels
Guido
G
Jacob
Tija C
TC
Pangalos
Menelas N
MN
Moss
Stephen J
SJ
D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D018682:GABA Agents / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009154:Mutation / Q000502:physiology; D009474:Neurons / Q000166:cytology*; D018408:Patch-Clamp Techniques / Q000379:methods; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014162:Transfection / Q000379:methods; D054875:Ubiquitination / Q000502:physiology*
D000779:Anesthetics, Local; D004791:Enzyme Inhibitors; D018683:Excitatory Amino Acid Agents; D018682:GABA Agents; D021122:Protein Subunits; D011963:Receptors, GABA-A; D013779:Tetrodotoxin