Glycine receptor internalization by protein kinases activation

• Published in: Synapse (New York, N.Y.) N.Y.), 2011-11, Vol.65 (11), p.1231-1238
• Main Authors: Velázquez-Flores, Miguel ángel, Salceda, Rocío
• Format: Article
• Language: English
• Subjects: Animals; Central nervous system; Cyclic AMP-Dependent Protein Kinases - metabolism; Cys-loop glycine receptor; cytochalasin D; Endocytosis - physiology; Enzyme Activation - physiology; Female; G protein-coupled receptors; glycine receptor phosphorylation; Glycine receptors; Immunoprecipitation; ionotropic receptor internalization; Kinetics; Male; Phosphorylation; Phosphorylation - physiology; Plasma membranes; Protein Binding - physiology; Protein kinase A; Protein kinase C; Protein Kinase C - metabolism; Radioisotopes; Radioligand Assay - methods; radioligand binding assay; Rats; Rats, Long-Evans; receptor cross-talk; Receptors, Glycine - metabolism; Retina; Retina - enzymology; strychnine; Synapses
• ISSN: 0887-4476; 1098-2396; 1098-2396
• DOI: 10.1002/syn.20963

Although glycine‐induced currents in the central nervous system have been proven to be modulated by protein kinases A (PKA) and C (PKC), the mechanism is not well understood. In order to better comprehend the mechanism involved in this phenomenon, we tested the PKA and PKC activation effect on the specific [3H]glycine and [3H]strychnine binding to postsynaptic glycine receptor (GlyR) in intact rat retina. The specific binding constituted about 20% of the total radioligand binding. Kinetic analysis of the specific binding exhibited a sigmoidal behavior with three glycine and two strychnine binding sites and affinities of 212 nM for [3H]glycine and 50 nM for [3H]strychnine. Specific radioligand binding was decreased (60–85%) by PKA and PKC activation, an effect that was blocked by specific kinases inhibitors, as well as by cytochalasin D. GlyR expressed in the plasma membrane decreased about 50% in response to kinases activation, which was consistent with an increase of the receptor in the microsomal fraction when PKA was activated. Moreover, immunoprecipitation studies indicated that these kinases lead to a time‐dependent receptor phosphorylation. Our results suggest that in retina, GlyR is cross‐regulated by G protein‐coupled receptors, activating PKA and PKC. Synapse 2011. © 2011 Wiley‐Liss, Inc.